Subjects -> PALEONTOLOGY (Total: 46 journals)
Showing 1 - 21 of 21 Journals sorted alphabetically
Acta Palaeontologica Polonica     Open Access   (Followers: 6)
Alcheringa: An Australasian Journal of Palaeontology     Hybrid Journal   (Followers: 7)
Ameghiniana     Open Access   (Followers: 1)
Annales de Paléontologie     Full-text available via subscription   (Followers: 7)
Annals of Carnegie Museum     Full-text available via subscription   (Followers: 1)
Boreas: An International Journal of Quaternary Research     Hybrid Journal   (Followers: 12)
Comptes Rendus Palevol     Full-text available via subscription  
European Journal of Protistology     Hybrid Journal   (Followers: 6)
EvoDevo     Open Access   (Followers: 4)
Facies     Hybrid Journal   (Followers: 10)
Fossil Record     Open Access   (Followers: 5)
Geobios     Full-text available via subscription   (Followers: 6)
Historical Biology: An International Journal of Paleobiology     Hybrid Journal   (Followers: 9)
Ichnos: An International Journal for Plant and Animal Traces     Hybrid Journal  
International Journal of Speleology     Open Access   (Followers: 3)
Journal of Paleolimnology     Hybrid Journal   (Followers: 6)
Journal of Paleontology     Hybrid Journal   (Followers: 11)
Journal of Quaternary Science     Hybrid Journal   (Followers: 31)
Journal of Vertebrate Paleontology     Full-text available via subscription   (Followers: 12)
Marine Micropaleontology     Hybrid Journal   (Followers: 2)
Micropaleontology     Full-text available via subscription  
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen     Full-text available via subscription   (Followers: 4)
Novitates Paleoentomologicae     Open Access   (Followers: 1)
Open Quaternary     Open Access   (Followers: 1)
Palaeogeography, Palaeoclimatology, Palaeoecology     Hybrid Journal   (Followers: 13)
Palaeontology     Hybrid Journal   (Followers: 18)
Palaeoworld     Hybrid Journal   (Followers: 3)
PALAIOS     Hybrid Journal   (Followers: 7)
Paläontologische Zeitschrift     Hybrid Journal   (Followers: 4)
Paleobiology     Full-text available via subscription   (Followers: 6)
PaleoBios     Open Access   (Followers: 1)
Paleoceanography     Full-text available via subscription   (Followers: 4)
Paleontological Journal     Full-text available via subscription   (Followers: 5)
Paleontological Research     Full-text available via subscription   (Followers: 3)
Palynology     Hybrid Journal   (Followers: 2)
Papers in Palaeontology     Hybrid Journal   (Followers: 1)
Quaternaire     Open Access   (Followers: 2)
Quaternary Research     Full-text available via subscription   (Followers: 20)
Quaternary Science Reviews     Hybrid Journal   (Followers: 25)
Review of Palaeobotany and Palynology     Hybrid Journal   (Followers: 2)
Revue de Micropaleontologie     Full-text available via subscription  
Rivista Italiana di Paleontologia e Stratigrafia (Research In Paleontology and Stratigraphy)     Open Access   (Followers: 2)
Spanish Journal of Palaeontology     Open Access  
Swiss Journal of Palaeontology     Hybrid Journal   (Followers: 4)
Vertebrate Anatomy Morphology Palaeontology     Open Access   (Followers: 2)
Zitteliana     Open Access   (Followers: 5)
Similar Journals
Journal Cover
Palaeogeography, Palaeoclimatology, Palaeoecology
Journal Prestige (SJR): 1.285
Citation Impact (citeScore): 2
Number of Followers: 13  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0031-0182 - ISSN (Online) 0031-0182
Published by Elsevier Homepage  [3203 journals]
  • Recurring cryptic ecosystems in Lower to Middle Devonian carbonate mounds
           of Hamar Laghdad (Anti-Atlas, Morocco)
    • Abstract: Publication date: 1 June 2019Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 523Author(s): Błażej Berkowski, Michał Jakubowicz, Zdzislaw Belka, Jan J. Król, Mikołaj K. Zapalski Exceptionally well-preserved fossil cryptic communities have been discovered in submarine cavities of the Lower and Middle Devonian (Emsian to Givetian) mud mounds in the Hamar Laghdad area (Anti-Atlas, Morocco). The cryptic biota encrusted the roofs of the cavities and grew predominantly oriented upside down. These unique coelobiotic communities were dominated by various solitary rugose corals, which very often displayed a “calice-in-calice” growth pattern. Apart from the rugosans, the cavities were inhabited by other sessile invertebrates: tabulate corals, cladochonids, crinoids and lithistid sponges. Many of the skeletons were encrusted by microbial structures. The high density of organisms overgrowing each other points to intensive competition for space in all studied Devonian submarine crypts. The late Emsian to latest Givetian cavities were colonised by various sets of coelobiotic inhabitants mostly originating from the surrounding deep-water marine environments. It is suggested that the local species pool was a decisive factor in determining the ecological succession and taxonomic structure of cryptic communities. The changes in taxonomic composition and diversity, over time and space, were primarily related to variations in local physical environment. Consequently, the communities in crypts affected by venting of high-temperature fluids or hydrocarbon seepage were of low diversity and included endemic elements and characteristically small specimens.
  • Aberrations in the infrabasal circlet of the cladid crinoid genus
           Cupulocrinus (Echinodermata) and implications for the origin of flexible
    • Abstract: Publication date: 15 May 2019Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 522Author(s): M.E. Peter Flexible crinoids (subclass Flexibilia) likely originated from the cladid crinoid genus Cupulocrinus or one of its immediate ancestors in the Middle to Late Ordovician. A remarkably constant and clade-defining character of flexible crinoids is the possession of three plates in the infrabasal circlet of the calyx. This character was a significant morphological modification for the origin of the flexible clade, resulting from the reduction of the number of infrabasal plates from five plates in the ancestral cupulocrinid.Of 615 museum specimens of Cupulocrinus sp. for which the number of infrabasal plates could be determined, 21 specimens, or 3.4%, displayed a deviation from the normal five infrabasals. Of the aberrant specimens, fifteen have four infrabasal plates, and six have six infrabasal plates. An additional aberrant specimen has five infrabasals, with one significantly reduced in size. Although the number of infrabasals is typically thought to be constant within a species, this trait appears to have been variable in the immediate ancestor of flexible crinoids, in the time period just before the number of infrabasals became fixed at three for the Flexibilia. This paper documents the range of aberrations within the infrabasal circlet of Cupulocrinus and considers the implications for the origin of the flexible crinoids.Graphical abstractUnlabelled Image
  • Palaeobiogeographic and tectonic significance of mid-Cretaceous
           invertebrate taxa from Batavia Knoll, eastern Indian Ocean
    • Abstract: Publication date: 15 May 2019Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 522Author(s): Toban J. Wild, Jeffrey D. Stilwell A newly described fossil suite from Batavia Knoll, eastern Indian Ocean, adds insight to the palaeobiogeographic connections between assemblages around the nascent Indian Ocean, during the breakup of Gondwana in the mid-Cretaceous (Albian and Cenomanian). Analyses were completed on the biotic similitude of the Batavia Knoll and five other suites from around the Indian Ocean, being northern Australia, central and southern Indian, Madagascar, and south-eastern Africa. Employing Jaccard coefficients (J) to determine degrees of similarity between the suites, it was determined that the Batavia Knoll invertebrate assemblage maintains strong connections to the others included in the study (J > 0.18), with the exception of the central Indian assemblages (J = 0.091). This pattern was followed by most of the other suites, cementing Batavia Knoll's palaeobiogeographic position within the East African Palaeobiogeographic Province. The results of the analysis also extended the eastern boundary of that province to include the northern coast of Australia, with fauna there exhibiting similar strong affinities with other circum-Indian suites.
  • Climatic controls on peat swamp formation and evolution since 1300 year
           BP as recorded by phytoliths in the Xishan Mountains, Jiangxi Province,
    • Abstract: Publication date: 15 May 2019Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 522Author(s): Xin-Rong Zhang, Yu Du, Chun-Mei Ma, Shuai-Fei Ping, Chong Feng, An-Ning Cui Over the past millennium, there have been several precipitation–temperature cycles characterized by instabilities in the eastern monsoon region in China, but the processes, factors, and anthropogenic activities potentially responsible remain poorly understood. In this study, we present an analysis of phytoliths from borehole core drilled through an ombrotrophic peat mire in Jiangxi Province, China. Our results record three climatic episodes over the past 1300 year: a warmer interval, c. 800–1305 CE, similar to the Medieval Warm Period (MWP); a cooler interval, c. 1305–1860 CE, similar to the Little Ice Age (LIA); and another warmer interval, as the climate entered the Present Warm Period (PWP) after c. 1860 CE. Quantitative analysis of phytolith assemblages demonstrates that the MWP comprised two intervals: the early MWP, c. 800–1140 CE, was progressively wetter in a warm–dry setting and late MWP, c. 1140–1305 CE, was warm and humid. The LIA also comprised two intervals: the early LIA, c. 1305–1610 CE, was cool and dry, and the late LIA, c. 1610–1860 CE was cool and humid. Some abrupt climate events occurred at: (1) c. 1050, 1110–1130, and 1780–1845 CE (wet events); (2) c. 1980–1990 CE (dry events); (3) c. 920 and 1770 CE (warm events); (4) c. 980 and 1050 CE (cold events). The transition from the MWP to the LIA, as indicated by phytoliths, was a gradual process that took c. 100 years, and exhibited frequent temperature fluctuations. Correlations between the phytolith assemblages and the solar activity, East Asia Summer Monsoon, El Niño, and La Niña are evident. Solar maxima and La Niña-like conditions are related to warmer and humid conditions that led to clay–sand accumulation during the MWP. Solar minima and El Niño-like conditions were associated with a cold and wet climate that led to peat accumulation during the LIA. These observations provide important insights into paleoclimatic change in the eastern monsoonal region of China, and provide a basis on which to understand the response of the Xishan Mountains in SE China to the MWP and LIA, and explore centennial-scale climate fluctuations and their driving mechanisms.
  • The Permian-Triassic transition in ocean island setting: Environmental
           disturbances and new high-resolution carbon-isotope record from the
           Qiangtang Basin, NW China
    • Abstract: Publication date: 15 May 2019Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 522Author(s): Xiugen Fu, Jian Wang, Chunyan Song, Zhongwei Wang, Shengqiang Zeng, Dong Wang The Permian-Triassic boundary (PTB) events such as carbon-isotope excursion, volcanism, and environmental disturbances are not well understood in an ocean island setting. Here, we develop a new case study for the Permian-Triassic transition in the Qiangtang Basin, Tibet, by combining existing biostratigraphy, new carbon-isotope data, sedimentological data, UPb zircon age, mineralogical and geochemical data. These new data defined the Permian-Triassic transition age as about 252.3 ± 0.9 Ma, corresponding to the lowermost sea level. A long-term negative carbonate carbon isotope trend is present at the same stratigraphic level in different depositional environments, strongly suggesting its global nature. However, our new ocean island setting is characterized by an abrupt shift in carbon isotope values across the level, which is different from many chemostrtigraphic studies that show a gradual shift in carbon isotope values across the event horizon. The most likely explanation for the abrupt shift in δ13C values is a sedimentary hiatus at this level in the study section. Three-stage climatic models through the PTB in the ocean island setting are identified: Stage 1 is characterized by a warm and humid climate with moderate chemical weathering; while a hot and humid climate with intense chemical weathering dominates stage 2; the climate in stage 3 is a relatively hot and arid climatic condition with weak chemical weathering.
  • Combining machine learning algorithms and geometric morphometrics: A study
           of carnivore tooth marks
    • Abstract: Publication date: 15 May 2019Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 522Author(s): Lloyd A. Courtenay, José Yravedra, Rosa Huguet, Julia Aramendi, Miguel Ángel Maté-González, Diego González-Aguilera, Mari Carmen Arriaza Since the 1980s an intense scientific debate has revolved around the hunting capacities of early hominin populations and the behavioral patterns of carnivores sharing the same ecosystem, and thus competing for the same resources. This debate, commonly known as the hunter-scavenger debate, fostered the emergence of a new research line into the Bone Surface Modifications (BSMs) produced by both taphonomic agents. Throughout the following 20 years, multiple studies concerning the action of carnivores have been developed, with a particular focus on the oldest archaeological sites in East Africa. Recent technological advances applied to taphonomy have provided new insight into carnivore BSMs. A newly developed part of this work relies on Geometric Morphometrics (GMM) studies aimed at discerning carnivore agency through the morphologic characterization of tooth scores and pits. GMM studies have produced promising results, however methodological limitations are still present. This paper presents the first combined application of Machine Learning (ML) algorithms and GMM to the analysis of carnivore tooth marks, generating classification rates of 100% between carnivore species in some cases.
  • A robust vegetation-based elevation transfer method for reconstructing
           Arctic polygon mire palaeo-microtopography
    • Abstract: Publication date: 15 May 2019Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 522Author(s): Annette Teltewskoi, Dierk Michaelis, Lutz Schirrmeister, Hans Joosten, Ulf Schiefelbein, Michael Manthey The reconstruction of past environments by means of macrofossil and pollen analysis is commonly based on the modern ecological preferences of the taxa that may have produced these fossils. Here we present a modelling approach, in which we use modern vegetation–surface height relationships to quantify past surface heights in an Arctic ice-wedge polygon mire. Vegetation composition and ground surface height (GSH) were assessed in a polygon mire near Kytalyk (Northeastern Siberia). Cluster analysis revealed five plant communities, which are clearly separated with respect to ground surface height, frost surface height and coverages of open water and vegetation. Based on the composition of modern vegetation we constructed two sets of potential fossil types (plant macrofossils and pollen), an extensive one and a more restricted one to reflect different conditions of preservation and recognisability. We applied Canonical Correspondence Analysis to model the relationships between potential fossil types and measured GSH. Both models show a strong relationship between modelled and measured GSH values and a high accuracy in prediction. Finally, we used the models to predict GSH values for Holocene peat samples and found a fair correspondence with expert-based multi-proxy reconstruction of wetness conditions, even though only a minor part of the encountered fossils were represented in the GSH models, illustrating the robustness of the approach. Our approach can be used to reconstruct palaeoenvironmental conditions in a more objective way and can serve as a template for further palaeoecological studies.Graphical abstractUnlabelled Image
  • The evolution and control of detrital sediment provenance in the middle
           and northern Okinawa Trough since the last deglaciation: Evidence from Sr
           and Nd isotopes
    • Abstract: Publication date: 15 May 2019Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 522Author(s): Fuqing Jiang, Zhifang Xiong, Martin Frank, Xuebo Yin, Anchun Li The Okinawa Trough (OT) is a large sink of sediments supplied by the East Asian continent. Identifying the provenance of the OT sediments is key to reconstructing the temporal and spatial variations of the terrigenous supply to this area and is important for understanding the impact of paleoclimatic and paleoceanographic variability on the sediment supply to this marginal sea over the late Quaternary. In this contribution, we show that radiogenic strontium (Sr) and neodymium (Nd) isotopes allow to efficiently distinguish Yellow and Yangtze/Taiwan River detrital sediments, and can be used to reconstruct distinct changes in the provenance of the detrital fraction of marine sediments from the middle and northern OT since the last deglaciation. The Sr and Nd isotope signatures are compared to those of the potential sediment sources, namely the Yellow and Yangtze Rivers, the Taiwan orogen, and volcanic material from the OT and nearby islands, and the relative contributions of these sources are reconstructed. The Sr and Nd isotope compositions of the detrital fraction in the two sediment cores recovered from the middle and northern OT show that the sediments mainly originated from the Yangtze River between 18 and 10.5 ka, which was caused by low sea level and a widely developed channel system on the continental shelf. During the period between 10.5 and 7.0 ka, the rising sea level resulted in elevated Yangtze and Yellow Rivers sediment input into the OT. Simultaneously, large-scale volcanic activity also contributed significant amounts of material to the OT. During the last 7.0 ka, besides important contributions from the Yellow River, the intensification of the Kuroshio Current resulted in increased delivery of sediment from Taiwan to the OT.
  • Sedimentary pyrite framboid size-frequency distributions: A meta-analysis
    • Abstract: Publication date: 15 May 2019Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 522Author(s): David Rickard Framboids, microscopic sub-spheroidal aggregates of pyrite microcrystals, are found in sediments of all ages and framboid size-frequency distributions are widely used to determine the oxygenation states of paleo-waters. Sedimentary framboid populations display unimodal log-normal size distributions as a consequence of the multiplicative central limit theorem in probability theory. The application of additive statistics to framboid populations and their consequent characterization in terms of arithmetic means and standard deviations is wrong because it predicts a subset of framboids with negative diameters.A meta–analysis of 377 sets of measurements of the diameters of 48,063 pyrite framboids from 104 sediment and sedimentary rock locations shows that the geometric mean diameter of sedimentary framboids is 6.2 μm and the geometric standard deviation is 1.5. Ninety-five percent of all sedimentary framboids have geometric mean diameters between 2.9 and 13.9 μm. The geometric mean diameter of modern syngenetic framboids formed within euxinic water columns is 4.7 μm and that of diagenetic framboids formed within sediments is 6.7 μm. The estimated measurement error is ±10%.Framboid mean diameters can be used to help discriminate the oxygenation state of paleo-waters. A minimum number of 30 measurements is required and ideally ≥100 measurements are recommended. The conflicting evidence reported in the literature for the application of framboid size-frequency measurements results mainly from the intrinsic nature of statistical analyses: there is always a finite chance that a particular framboid size-frequency distribution is a result of either syngenetic or diagenetic processes. Including the systematic stereological error in framboid size measurements, the geometric mean size range for syngenetic framboids is 2.9–10.9 μm and that for diagenetic framboids 3.1–20.9 μm. This suggests a significant overlap in geometric mean diameters of framboids from euxinic and non-euxinic environments between ~3 and ~11 μm. Geometric mean framboid diameters within this size range are not robust proxies for paleo-water oxygenation conditions. The origin of the smaller sizes of syngenetic compared with diagenetic framboids appears to be related to the limited time available for framboid crystal growth within the water column. The statistical uncertainty in assigning particular framboid size-frequency distributions to defined oxygenation conditions results mainly from (a) some diagenetic framboids forming over a limited time, thereby also producing smaller framboids and (b) mixtures of syngenetic and diagenetic framboid populations through unavoidable time-averaging of samples. The absence of any significant differences in the sizes of modern and ancient framboids indicates that framboids do not continue to grow over extended time periods: once formed they remain the same over geologic time periods and only change through infilling, overgrowth and recrystallization. The result is that ancient framboids may sample the contemporary paleoenvironment in the sedimentary system in which they are found.
  • Radiocarbon dates of two musk ox vertebrae reveal ice-free conditions
           during late Marine Isotope Stage 3 in central South Norway
    • Abstract: Publication date: Available online 22 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Anne Karin Hufthammer, Atle Nesje, Thomas F.G. Higham One of the most reliable proofs of terrestrial ice-free conditions within Stadials is the presence of terrestrial vertebrate fauna that require access to vegetation in the winter, for example sedentary birds such as Ptarmigans and herbivorous mammals in particular. The musk ox (Ovibos moschatus) is an example of the latter; modern-day distributions of this species are limited to areas with low snow accumulations. In this paper we discuss the discovery of musk ox bones in Norway. Recently obtained radiocarbon dates on this material demonstrate the presence of this species 41–35 cal kyr B.P. in southern Norway during late Marine Isotope Stage 3 (MIS3). Furthermore the dates have implications for the interpretation of climate and environmental conditions; indicating the existence of a small ice cap in the mountains and climate and vegetation supporting a large mammal fauna in South Norway at that time.
  • Paleoceanographic changes across the Latest Danian Event in the South
           Atlantic Ocean and planktic foraminiferal response
    • Abstract: Publication date: Available online 21 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Sofie Jehle, André Bornemann, Anna Friederike Lägel, Arne Deprez, Robert P. Speijer A number of short warming events occurred during Paleocene and Eocene, of which the “Paleocene-Eocene Thermal Maximum” (PETM, 56 Ma) is the most severe and most investigated event. The less known “Latest Danian Event” (LDE) at 62.2 Ma represents a 200 ky-lasting warming phase, superimposed on a long-term cooling trend after the Early Paleocene. South Atlantic ODP Site 1262 data, covering ~1 myr, indicate a warming of the entire water column by 1.5–2.6 °C, accompanying a prominent negative carbon isotope excursion (~0.9–1.1‰) and a long-term re-organization of the planktic foraminiferal fauna associated with the LDE. This study unravels a different paleoceanographic evolution of the upper ocean structure compared to results from Pacific ODP Site 1210. Unlike the Pacific, the Atlantic site lacks an apparent change of stratification as well as an overall dominance of thermocline dwelling planktic foraminifera species and a low abundance of surface dwelling photosymbiotic foraminifera. Within the LDE, indications for a slightly enhanced stratification of the upper water column and transient warming were indicated when surface dwelling planktic foraminifera became temporarily more abundant. The long-term evolution in planktic foraminifera with the disappearance of Praemurica at the LDE onset and a contemporaneous rise in Morozovella is similar to the trends reported from Shatsky Rise ODP Site 1210.
  • In search of Silurian/Devonian boundary conodont markers in carbonate
           environments of the Prague Synform (Czech Republic)
    • Abstract: Publication date: Available online 21 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Aneta Hušková, Ladislav Slavík Conodonts from two of the most representative sections in the Prague Synform were studied in search of alternative biostratigraphic markers of the Silurian/Devonian boundary. The Na Požárech and Praha-Radotín sections, with contrasting lithologies, were chosen to study changes in conodont faunas in relation to different carbonate facies – i.e., shallower- and deeper-water carbonates around the Silurian/Devonian boundary in the type area. Apart from icriodontids, the differences in bathymetry were also expected to affect the diversity of taxa of the family Spathognathodontidae, which is generally the most abundant and the most tolerant clade found in different carbonate environments at this stratigraphic level. Although the Scyphocrinites Horizon is developed at both study localities, the microfacies analysis confirmed significant differences in depositional environments at around the Silurian/Devonian boundary. Abundant conodont material from the two sections (more than one thousand elements) showed a high diversity and disparity in both the Spathognathodontidae and Icriodontidae. Altogether, 18 taxa were identified, but many forms still require a formal description. A new spathognathodontid taxon, Zieglerodina petrea sp. nov., described herein, is easily distinguishable because of its distinct morphology in denticulation of the blade, and its first occurrence is just above the base of the Devonian in both sections. It also has been identified in conodont collections from Morocco and the Carnic Alps, as such its biostratigraphic significance can be extended to peri-Gondwana. Although the stratigraphic occurrence and global significance of this promising conodont taxon still has to be tested in other areas, current data suggest it might have a great potential for identifying the base of the Devonian in sections where critical graptolite and icriodontid taxa are missing.
  • The relation of a coastal environment to early diagenetic clinoptilolite
           (zeolite) formation - New data from the Late Cretaceous European Basin
    • Abstract: Publication date: Available online 21 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Agata Jurkowska, Marcin Barski, Elżbieta Worobiec Clinoptilolite, an authigenic mineral of the zeolite group, is commonly considered as a product of rhyolitic volcanic glass transformation during diagenesis of carbonate pelagic/hemipelagic sediments of Cretaceous-Paleogene age. Another, subordinate way of clinoptilolite formation that has been suggested in the literature is its precipitation during diagenetic transformation of carbonate sediments enriched with biogenic silica. The observations concerning transformation of the latter into zeolite are scarce and mostly based on Cretaceous pelagic, hemipelagic and shallow marine deposits, and post-Cretaceous sediments in which there was no volcanic material. The mechanism of diagenetic clinoptilolite formation in volcanic-free sediments, as well as the role of the depositional setting in its precipitation, is not well understood. In carbonates of the NW part of the European Basin (west side of the Łysogóry-Dobrogea Archipelago) studied here, the clinoptilolite is associated with opal-CT (from the dissolution of sponge spicules) and a detrital clays are documented for the first time in a Cretaceous coastal environment. The carbonates were deposited in a coastal environment which was under the influence of weak currents delivering sponge spicules (biogenic opal) from the offshore zone and the terrestrial input was transported by rivers from a neighboring island. The lush plant vegetation, with numerous pteridophytes and conifers, within a warm (sub-tropical or tropical) and humid climate enhanced the terrestrial weathering of clays and feldspars. This unique combination of elevated silica concentrations (from sponge spicules dissolution) and aluminum availability (from terrestrial weathering of feldspars in a subtropical climate) during the early diagenesis combined with alkalinity triggered by organic matter decomposition, enhanced the clinoptilolite formation a few centimeters below the seabed. The investigation demonstrates a novel route by which pore-fluids enriched with silica and aluminum initiate clinoptilolite formation during the very early stage of diagenesis, a few centimeters below the seafloor. The clinoptilolite distribution in Late Cretaceous silica rich deposits (with no volcanic input) of the European Basin is always associated with opal-CT, from sponge spicules and elevated terrestrial input (clays). Taking into account the distinctive Campanian-Maastrichtian sedimentation in the epicontinental European Basin, composed almost exclusively of pure pelagic carbonates, the depositional settings in which the silica and aluminum were available in pore waters was restricted to the part of the basin influenced by terrestrial input. This leads to the conclusion that clinoptilolite formation in volcanic-free sediment is an indicator of not only enhanced sponge silica availability but also the close proximity of the source area.
  • Terrestrial and marginal-marine record of the mid-Cretaceous Oceanic
           Anoxic Event 2 (OAE 2): High-resolution framework, carbon isotopes, CO2
           and sea-level change
    • Abstract: Publication date: Available online 21 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Jiří Laurin, Richard S. Barclay, Bradley B. Sageman, Robin R. Dawson, Mark Pagani, Mark Schmitz, Jeffrey Eaton, Francesca A. McInerney, Jennifer C. McElwain Oceanic Anoxic Event 2 (OAE2; c. 94.5–93.9 Ma) offers insight into the mechanisms of past climate change linked to organic productivity and carbon sequestration. It has been studied extensively, but the vast majority of data come from marine records, thus providing an incomplete view of past climate dynamics. Here we integrate new high-resolution data and published records on depositional environments, the carbon-isotope composition of bulk organic carbon (δ13Corg) and plant cuticles (δ13Ccut), and stomatal-index values, a proxy for pCO2, in well-preserved terrestrial through marginal-marine archives of the initial phase of OAE2. The study area is located on the western margin of the Western Interior Seaway (southwestern Utah). Age constraints are based on a new U-Pb bentonite age and correlation to an orbitally calibrated interval of the Bridge Creek Limestone. n-Alkane abundance suggests predominance of terrestrial contributions to bulk organic carbon for most samples. Despite similarities between carbon-isotope variations and transgressive-regressive shoreline movements, it is argued that δ13Corg and δ13Ccut are not strongly affected by local variables. A series of negative, ~2‰ carbon-isotope excursions is identified and attributed to changes in the size and isotopic value of the atmospheric CO2 reservoir. The temporal spacing of these anomalies (80–120 kyr) is consistent with changes in insolation modulated by orbital eccentricity. A systematic, phase-shifted relationship between the negative carbon-isotope excursions and transgressive increments further suggests a link between carbon-cycle perturbations and meter-scale sea-level change on the 100-kyr time scale. A conceptual model involving insolation-controlled aquifer charge/discharge and biomass burial/degradation in the monsoonal belt is proposed. The framework presented here is available to facilitate further research on the interplay of terrestrial and oceanic carbon reservoirs during OAE2.
  • Middle Triassic Pentasauropus-dominated ichnofauna from western Gondwana:
           Ichnotaxonomy, palaeoenvironment, biostratigraphy and palaeobiogeography
    • Abstract: Publication date: Available online 20 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Abdelouahed Lagnaoui, Ricardo N. Melchor, Eduardo S. Bellosi, Pablo M. Villegas, Nahuel Espinoza, Aldo M. Umazano Quadruped trackways of large pentadactyl footprints are reported from the Middle Triassic (Anisian-Ladinian) Cerro de las Cabras Formation of the Cuyo Basin, Mendoza Province, central-western Argentina. The track-bearing strata are interpreted as deposited by sheetfloods in a mixed flat where water was ponded in a playa-lake setting. The vertebrate trackways are assigned to the ichnogenus Pentasauropus, originally described from the Upper Triassic Elliot Formation of South Africa, based on the presence of five equally spaced digit imprints that form an anteriorly convex broad arcuate pattern. A new ichnospecies, Pentasauropus argentinae nov. isp., is erected for the Argentinian material because of the distinct heteropody, inward rotation of the pes and outward rotation of the manus imprints, and the presence of palm/sole traces, and the diagnosis of the ichnogenus is emended. Pes/manus set arrangement and trackway patterns indicate a sprawling limbed trackmaker with an abducted posture for the fore-limbs and at least a semi-abducted posture for the hindlimbs, which suggests that the trackmaker was a kannemeyeriiform dicynodont. Associated archosaur ichnotaxa (Chirotherium barthii, Chirotherium cf. C. rex, Isochirotherium cf. I. coureli) point to a Middle Triassic age for the trackway-bearing strata in agreement with bracketing geochronological data. The rare occurrence of the therapsid footprint Dicynodontipus isp. is also compatible with the inferred age. The moderate abundance and oldest occurrence of Pentasauropus from three areas in Argentina suggest an origin for this ichnogenus in southwestern Gondwana, and presumably this area was a faunal exchange gate between southeastern and southwestern Gondwana and south Gondwana and North America.Graphical abstractUnlabelled Image
  • Paleoenvironmental signature of the Selandian-Thanetian Transition Event
           (STTE) and Early Late Paleocene Event (ELPE) in the Contessa Road section
           (western Neo-Tethys)
    • Abstract: Publication date: Available online 20 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Rodolfo Coccioni, Fabrizio Frontalini, Rita Catanzariti, Luigi Jovane, Daniel Rodelli, Ianco M.M. Rodrigues, Jairo F. Savian, Martino Giorgioni, Bruno Galbrun Sedimentary records of the Early Cenozoic indicate a series of events with climatic and carbon cycle variability known as hyperthermals. A ~350-kyr-long event of environmental disruption during the Paleocene, not described before and here named Selandian–Thanetian Transition Event (STTE), has been recognized and well constrained in the western Tethys Contessa Road section (Gubbio, Italy) through high-resolution biostratigraphic, geochemical, and rock-magnetic data. The STTE exhibits peculiar stressed ecological responses among calcareous nannofossils and foraminifera, which highlight marked environmental perturbation affecting the biosphere. The environmental instability is not confined within the photic zone but extends to the seafloor leading to little more trophic conditions of the sea surface waters with an enhanced, but of short measure, nutrient availability on the seafloor conditions and marked rise of lysocline. Magnetic Susceptibly (MS) is dominantly controlled by the balance between carbonate productivity and detrital supply, as evidenced by the strong correlation between MS and CaCO3 (%) (r2 = −0.72). However, we also document two components in the isothermal remanent magnetization (IRM) and first-order reversal curves (FORC) diagrams that prove the occurrence of biogenic magnetite throughout the STTE. Systematic variations in bio-geochemical and magnetic parameters show the relative abundance of carbonate production (or inversely dissolution of carbonate) versus detrital supply during the STTE, which induced higher populations of magnetotactic bacteria through increased terrigenous input and, therefore, increased nutrient supply. Noteworthy, the uppermost part of the STTE includes the equivalent of the suspected hyperthermal, short-lived Early Late Paleocene Event (ELPE). The ELPE event shows an episode of increase in magnetic properties of the sediments, including an increase in magnetofossil concentration, as indicated by IRM components and FORC diagrams. The comparison of biotic and abiotic records throughout the STTE at Contessa Road section with available data across the ELPE from former investigated ocean and land-based sites provides lines of evidence that this latter event might be indeed only the terminal part of a long-lasting environmental change than hitherto supposed.
  • Geomorphological response to the Lateglacial-Holocene palaeoenvironmental
           changes in the NE piedmont of the Sierra de Aconquija (Tafí Valley, NW
    • Abstract: Publication date: Available online 20 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): José Luis Peña-Monné, María Marta Sampietro-Vattuone Fluvial basins located on the NE side of the Sierra de Aconquija and facing the Tafí valley (NW Argentina) enable a study of the sedimentary records of valleys and alluvial fans that have been subject to glacial and periglacial dynamics since the Fini-Pleistocene to Upper Holocene. i) The oldest morphosedimentary unit (H1A) encompasses the Late Glacial and Early Holocene. A relationship was established linking fluvioglacial terraces to records from El Rincón profile (Younger Dryas) belonging to the most important glacial phase (G1) in the cirques found in the NE of Aconquija; ii) similarly, there is a G2 glacial phase (Neoglacial) that could be connected with the H1B records of the Muñoz River and dated to Early-Middle Holocene; iii) the final units (H2 and H3 from Upper Holocene) form a stepped terrace in the valleys and were interpreted as corresponding to the rock glacier phases from the high mountains and highlighting those that were active during the LIA.
  • Quantifying the community turnover of the uppermost Wenlock and Ludlow
           (Silurian) conodonts in the Baltic Basin
    • Abstract: Publication date: Available online 20 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Andrej Spiridonov, Jovita Samsonė, Antanas Brazauskas, Robertas Stankevič, Tõnu Meidla, Leho Ainsaar, Sigitas Radzevičius The Homerian to Ludfordian interval of the mid to late Silurian Period was a time of significant changes in conodont communities, global climate, oceanographic patterns and biogeochemical cycles. The Mulde and the Lau events are preeminent examples of globally recognized conodont extinction episodes from this interval in Earth's history. The Silurian Baltic Basin is the most suitable locality, globally, for studying these perturbations to the ocean-atmosphere system, since there is an extensive record of conodont taxa occurrences, their communities, and their environments spanning across shore-face to open-ocean settings. In this study, we present new conodont and δ13C data from the upper Homerian to Ludlow interval from two core sections – Gėluva-99 and Gėluva-118, representing shelfal environments, and the numerical conodont data from the Viduklė-61 section, from deep-water settings, and compare them with patterns of conodont diversity change, as revealed in the data-rich Milaičiai-103 core section. For this purpose, we explored the stratigraphically tied time series of conodont diversity changes employing recurrence and cross-recurrence plots – the binary similarity matrices that are used for deciphering complex spatial and temporal dynamic patterns. The cross-recurrence plots were used as a means of synchronizing the geological sections by applying dynamic time warping and the newly described moving window median recurrence point search algorithms. The results revealed that the conodont community compositional data are sufficiently temporally and spatially coherent to be reasonably used for synchronizing geological records. Moreover, the sudden state transitions detected in the cross-recurrence plots suggest that the Lau Event was of great importance for conodont community evolution in the studied time slice.
  • Holocene succession patterns of land snails across temperate Europe: East
           to west variation related to glacial refugia, climate and human impact
    • Abstract: Publication date: Available online 20 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Michal Horsák, Nicole Limondin-Lozouet, Lucie Juřičková, Salomé Granai, Jitka Horáčková, Claude Legentil, Vojen Ložek Although Holocene mollusc succession has been described from many temperate European sites, no attempt to analyse diversity patterns across the continent from east to west has yet been done. Here, we assembled and quantitatively analysed 54 most representative Holocene successions categorized into five climatic and geomorphological regions. These were defined along a longitudinal transect across temperate Europe, i.e. West Carpathians, Bohemian Massif, West Continental, Atlantic France, and Atlantic England. We found a clear east-west gradient in the Holocene dynamic of land snail assemblages, correlating mainly with the changes in strictly forest species richness. Representation of these species increased towards the east in accordance with known position of glacial refugia in the Carpathian Mountains. The West Carpathians acted as a unique refugium, expressing the highest temporal stability of Holocene snail assemblages, with a sharp increase in strictly forest species richness already in the Early Holocene. In contrast, Atlantic regions, characterized by low elevation and low topographical heterogeneity, were always poor in number of strictly forest species with no or only shallow increase of their richness in the Holocene climatic optimum. Further reduction in the second half of the Holocene, along with the increase of strictly open-country species richness correlates with higher human impact on mollusc faunas in lowland and flat regions. These factors can explain the previously reported impoverishment of modern western European forest fauna and have apparently also contributed to regional diversity patterns throughout the Holocene. Among the regions, we found three types of successional trajectories in the composition changes of Holocene molluscs, mirroring the above mentioned east-west gradient, with the West Carpathians having the most distinctive fauna. Our results show that distance from glacial refugia, landscape topography, and also human impact importantly shaped the species richness dynamic and successional pathways of Holocene land-snail fauna across temperate Europe.
  • Paleoecology of Pleistocene mammals and paleoclimatic change in South
           China: Evidence from stable carbon and oxygen isotopes
    • Abstract: Publication date: Available online 20 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Fajun Sun, Yang Wang, Yuan Wang, Chang-zhu Jin, Tao Deng, Burt Wolff The role of climate change in the evolution and diversification of hominoids remains a hotly debated issue. Stable isotope analyses of fossil mammals that coexisted with the hominoids can provide insights into hominoid palaeoenvironments and shed light on this debate. Here, we report results of stable carbon and oxygen isotope analyses of tooth enamel samples from a variety of Pleistocene mammals including pandas, deer, elephants, pigs, rhinos, and bovids from two hominoid fossil localities (Yugong Cave and Baxian Cave) in South China. Enamel δ13C values indicate that most of the mammals living in the study area during the late Middle Pleistocene had C3-based diets but a small number of individuals consumed some C4 grasses. This indicates the presence of C4 plants in the region during the late Middle Pleistocene, most likely in patches of open areas in a predominantly forested environment. However, during the early Late Pleistocene, all of the mammals examined had C3-based diets, except one bovid and one panda that may have ingested small amounts of C4 plants. This indicates a dense forested environment with little C4 grasses during the early Late Pleistocene. Like the Early Pleistocene pygmy panda (Ailuropoda microta) from Yanliang Cave, the late Middle Pleistocene Ailuropoda baconi from Yugong Cave and the early Late Pleistocene Ailuropoda melanoleuca from Baxian Cave had higher mean diet-δ13C values than other co-occurring herbivores, indicating they preferred relatively open forest habitats and had more restricted diets compared to other mammals. The reconstructed mean paleo-meteoric water δ18Ow values are lower than the annual average δ18Ow value of modern precipitation in the region, suggesting that the climatic conditions during the times when these Pleistocene mammals were alive were colder and/or wetter than today. In addition, δ18O values of the obligate drinkers (pigs, rhinos, bovids) display an overall decreasing trend, accompanied by increased range of δ18O variations, from the Early Pleistocene to the early Late Pleistocene. This suggests that the regional climate became colder and/or wetter, with increased seasonality, from the Early Pleistocene to the early Late Pleistocene, likely related to intensified glaciation. The change in climate to colder conditions may be responsible for the extinction of the Gigantopithecus in this region.
  • Effects of age and environment on stable carbon isotope ratios in tree
           rings of riparian Populus
    • Abstract: Publication date: Available online 19 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Jonathan M. Friedman, Craig A. Stricker, Adam Z. Csank, Honghua Zhou Stable carbon isotopes of riparian tree rings are enabling improved reconstruction of past climate variability, but this advance is limited by difficulty distinguishing the effects of tree age from those of climate. We investigated relative influence of age and climate trends in genus Populus, which dominates floodplain forests in Europe, Asia and North America. We related precipitation and river flow to annual variation in stable carbon isotope ratio (δ13C) in trees with a broad distribution of ages spanning two hundred years. On the floodplain of the lightly regulated Little Missouri River, North Dakota, USA, we examined a total of 845 rings from seven specimens of cottonwood tree (Populus deltoides W. Bartram ex Marshall ssp. monilifera [Aiton] Eckenwalder). Cottonwood δ13C decreased from pith to bark in whole wood, but this trend was almost completely eliminated in purified cellulose. The δ13C offset between whole wood and cellulose increased from pith to bark, consistent with trends of decreasing cellulose and increasing hemicellulose as a proportion of whole wood. While annual ring width was correlated with monthly precipitation from April through June, δ13C showed strong correlations only in June and July, suggesting that these complementary proxies allow resolution of seasonal variation in water availability. We conclude that past climate can be reconstructed from δ13C of purified cellulose from cottonwood without detrending for tree age.
  • A Late Pleistocene and Holocene vegetation and environmental record from
           Shuangchi Maar, Hainan Province, South China
    • Abstract: Publication date: Available online 19 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): John Dodson, Jianyong Li, Fengyan Lu, Wenchao Zhang, Hong Yan, Shuan Cao Shuangchi is a maar in the volcanic province of tropical northern Hainan Island, South China. A radiocarbon dated record of pollen, charcoal, organic carbon and some fossil algae provides a discontinuous record from its sediments covering the last 20,000 years. The fossil record is broken in places by abrupt pulses of inorganic material washed into the basin from the crater walls, presumably during periods of high magnitude storms. Last Glacial Maximum was marked by forest but with a high component of grassland, suggesting a drier and cooler climate than today. Forest recovery was rapid from about 9500 years ago and a peak in tropical rainforest taxa persisted until about 5000 years ago and this appears to represent peak warming in the region. From about 5000 years ago until present there is evidence of human impact, and fire was a tool used to clear forest. The human impact signal varies across Hainan which suggests that the level of human resource use was localised at least for several millennia. Human impact signals appear to be widespread from about 2000 years ago.
  • Biotic interchange through lowlands of Tibetan Plateau suture zones during
    • Abstract: Publication date: Available online 16 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Jia Liu, Tao Su, Robert A. Spicer, He Tang, Wei-Yu-Dong Deng, Fei-Xiang Wu, Gaurav Srivastava, Teresa Spicer, Truong Van Do, Tao Deng, Zhe-Kun Zhou A substantial biotic interchange took place between Gondwanan India and Laurasia immediately following the India-Eurasia collision. Located just north of the collision zone, the role of the Tibetan Plateau in the geographic interchange of biota is still unknown because lack of fossil evidence. Here, well-preserved samara fossils of Ailanthus (the family Simaroubaceae) are described from the Lunpola and Nima basins, central Tibetan Plateau, ranging in age from the latest Paleocene to the Late Oligocene. These fossils are the largest samara fossils of this genus found so far. Characteristics such as the main ventral vein located in the intramarginal part of the samara, and the stylar scar located on the midline of the seed suggest that they represent a new species, which we herein name Ailanthus maximus J. Liu, T. Su et Z.K. Zhou, sp. nov. These findings greatly expand the known spatial distribution of Ailanthus in the Paleogene, and suggest that the Tibetan Plateau has played an important role in the migration of biota between Gondwanan India and the Northern Hemisphere. In addition, A. maximus is morphologically similar to A. triphysa, a living species which is naturally distributed in tropical and subtropical regions in Southeast Asia at elevation no more than 600 m, indicating a tropical or subtropical lowland environment in the central Tibetan Plateau during the latest Paleocene to Late Oligocene. Moreover, together with previous paleoaltimetric estimates, we propose that tropical or subtropical lowlands along the Bangong-Nujiang Suture Zone and the Yarlung-Zangpo Suture Zone existed in some parts of the Tibetan Plateau during the Paleogene only obtained their current elevation during the Neogene.
  • The conodont Paroistodus horridus (Barnes and Poplawski) as a new
           biostratigraphical tool for the middle Darriwilian (Ordovician)
    • Abstract: Publication date: Available online 16 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Ana Mestre, Susana Heredia This contribution develops an analysis on the conodont Paroistodus horridus (Barnes and Poplawski) from several Argentine Precordilleran sections. From these collections, we have established that P. horridus occurs from the Lenodus crassus Zone to the Amorphognathus tvaerensis Zone (Darriwilian to early Sandbian). This study recognizes several primary morphological features of P. horridus which vary through the Darriwilian and three evolutionary morphological types can be identified: early form, middle form with two stages, and late form. The co-occurrence of index conodonts with the successive stages of this evolutionary development allowed a significant biostratigraphical value to be assigned for each different morphological type of P. horridus. Based on this information, we propose a detailed biostratigraphical control and correlation with equivalent strata from Canada, China, Australia, United States, Norway, and western Central Asia.
  • Holocene environmental change at Inle Lake, Shan State, Myanmar, and its
           implications for the regional development of agriculture
    • Abstract: Publication date: Available online 15 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Geoffrey Hope, Sander van der Kaars, Janet Finn, Kyaw zay Moe We report pollen, charcoal and diatom records from the upper 4 m of a core from Inle Lake, Myanmar, spanning the entire Holocene, to investigate the changing palaeoenvironments in which early agriculture developed. From 12,000 to 10,500 cal yr BP a grass swamp existed until it was flooded by rising lake levels, indicated by the onset of marl deposition at the site. The onset of higher lake levels coincided with a transition from conifer-rich forest to mixed deciduous-evergreen forest, and a reduction in local biomass burning. Lake levels remained high until 6400 cal yr BP, thereafter fluctuating with possible dry phases at 4050, 2400 and 1100 cal yr BP. Increased burning is apparent from 2200 cal yr BP inferred to represent the onset of human forest clearance to its very reduced state today. The Inle Lake record compares with Holocene sequences in China, Thailand and India and marine cores south of Myanmar, which similarly show a regional pattern of drier conditions in the Holocene early Greenlandian stage, followed by maximum lake levels in the early Northgroppin stage. Fluctuating lake levels are evident in the later Northgrippian and Meghalayan stages after 6000 cal yr BP. This pattern coincides with precessional reduction in summer insolation in the region, which weakens the Asian Monsoon. The present-day bare catchments of Inle Lake probably mostly resulted from forest destruction over the last 2000 years although hints of human presence can be inferred throughout the older record.
  • Comparative Lower-Middle Ordovician conodont oxygen isotope
           palaeothermometry of the Argentine Precordillera and Laurentian margins
    • Abstract: Publication date: Available online 15 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Guillermo L. Albanesi, Christopher R. Barnes, Julie A. Trotter, Ian S. Williams, Stig M. Bergström Stratigraphic, palaeontologic, and palaeomagnetic data support a hypothesis that argues for the Argentine Precordillera rifting from the southwestern margin of Laurentia in low latitudes during the Cambrian, migrating across the Iapetus Ocean, colliding with the Gondwanan margin in the late Middle Ordovician, and receiving glaciogenic sediments in the Late Ordovician. An alternative model proposes that the Precordillera originated as a low-latitude segment of Gondwana, migrated southward through major transform faulting toward high latitudes in the late Middle Ordovician, to reach its present position in the Devonian. New conodont oxygen isotope compositions (δ18Ophos) have been determined by ion microprobe SHRIMP II using samples from both the Precordillera and Laurentia (Marathon area of Texas, Wilcox Pass in Alberta, and western Newfoundland). Significantly, the δ18O values of conodonts from all four widely separated areas show a consistent pattern of a cyclic but overall increasing trend in δ18O (ca. 16 to 18‰) hence ocean cooling through the Early and Middle Ordovician. An apparent change occurs at the basal Late Ordovician, where δ18O values obtained from conodonts in the uppermost sample from the Precordillera are significantly higher (+1.5‰) than those from Laurentia. Albeit from a single sample, this higher value implies significantly cooler conditions, as would be anticipated with a southerly (poleward) migration of the Precordillera (irrespective of either hypothesis). The virtual absence of conodont-bearing carbonates in most of the Precordilleran Upper Ordovician precluded analysis of younger samples. When combined with existing macrofaunal and palaeomagnetic data, the oxygen isotope data would tend to favour the model of a drift of the Precordillera from tropical to higher latitudes during the Ordovician; however, further studies are needed to determine unequivocally whether the Precordillera originated from southern Laurentia (Ouachita embayment). These new oxygen isotope values provide the best and regionally most consistent data through the Early-Middle Ordovician.
  • Conodont biostratigraphy and magnetic susceptibility of Upper Devonian
           Chattanooga Shale, eastern United States: Evidence for episodic deposition
           and disconformities
    • Abstract: Publication date: Available online 13 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): D. Jeffrey Over, Emily Hauf, Jenelle Wallace, Josephine Chiarello, Jin-Si Over, Geoff Gilleaudeau, Yi Song, Thomas J. Algeo On the western margin of the Nashville Dome, the Upper Devonian Chattanooga Shale in the Dupont GHS drillcore consists of 4.2 m of Frasnian strata and 9.1 m of Famennian strata that unconformably overlie the Sellersburg Formation. Three Frasnian, seven Famennian, and one Tournaisian conodont biozones are recognized. The Frasnian-Famennian boundary is on a disconformity. To the northeast in the southern Illinois Basin, the New Albany Shale in the BCC drillcore consists of 35 m of Givetian and Frasnian strata and 30 m of Famennian strata that conformably overlie the Sellersburg Formation. One Givetian, four Frasnian, and three of the four lowest Famennian conodont zones are recognized. The Frasnian-Famennian boundary is conformable and constrained to within a 5 cm interval. Bulk magnetic susceptibility (MS) shows a long-term increase through most of the Frasnian. Shorter-term MS trends were observed in association with depositional pulses linked to global sea-level rises and highstand system tracts, characterized by total organic carbon (TOC) maxima — eight trends were resolved in the DGHS core, and six in the BCC. The high-frequency shifts in δMS likely represent Milankovitch-band sea-level and depositional cycles at a scale that cannot be resolved based on the condensed and irregular nature of the depositional packages. Gamma ray counts in the DGHS peak in association with the eight depositional cycles, with a TOC peak at the base of each cycle.
  • Factors affecting the preservation and distribution of cetaceans in the
           lower Miocene Gaiman Formation of Patagonia, Argentina
    • Abstract: Publication date: Available online 13 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): José I. Cuitiño, Mónica R. Buono, Mariana Viglino, Nicolás D. Farroni, Santiago Bessone Factors affecting cetacean preservation and distribution in ancient sedimentary successions are not well understood. Actualistic studies have focused on coastal and deep marine examples, and little is known about taphonomic processes occurring within shelf environments. In this paper, we integrate sedimentological, taphonomic and palaeontological data for the cetacean-bearing lower Miocene Gaiman Formation from Patagonia, Argentina, to analyse which factors affected the distribution and preservation of cetaceans in several localities of the Southwestern Atlantic. Facies analysis shows that the formation represents a transgressive-regressive stratigraphic cycle, with palaeoenvironments including coastal, storm-dominated shoreface, inner shelf embayment and open inner shelf. Cetacean remains show preservation styles varying from isolated elements to articulated specimens, with nearly all remains restricted to both embayment and open marine inner shelf settings. Two fossil cetacean assemblages are recognized: Assemblage A comprises small-sized odontocetes dominated by Platanistoidea, preserved mostly in inner shelf embayment deposits; and Assemblage B comprises large-sized odontocetes and mysticetes, dominated by Physeteroidea and Balaenopteroidea, preserved mostly in open inner shelf deposits. Cetacean preservation style is controlled by a combination of palaeoenvironmental conditions, such as energy and sedimentation rate, and by biological factors, such as cetacean body plan and its impact on carcass buoyancy. Ecological factors may also explain the stratigraphic distribution of cetaceans between coastal and oceanic assemblages. This novel integrative and multidisciplinary analyses improves our knowledge of cetacean taphonomy in shelf environments.
  • An integrated carbon and oxygen isotope approach to reconstructing past
           environmental variability in the northeast Atlantic Ocean
    • Abstract: Publication date: Available online 13 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): David J. Reynolds, Ian R. Hall, Sophie M. Slater The combined influence of temperature and the isotopic composition of the seawater [δ18Ow] often precludes the use of oxygen isotope (δ18O) records, derived from marine carbonates, to reconstruct absolute seawater temperatures, without the application of an independent δ18Ow proxy. Here we investigate the application of carbon isotope records (δ13Cshell), derived from the long-lived marine bivalve Glycymeris glycymeris, as a proxy for δ18Ow variability. Our analyses indicate G. glycymeris δ13Cshell data derived from growth increments>20 years of age contain strong ontogenetic trends (−0.013‰ yr−1, R = 0.98, P 
  • Pollen and non-pollen palynomorph analyses of Upper Holocene sediments
           from Dianshan, Yangtze coastal lowlands, China: Hydrology, vegetation
           history and human activity
    • Abstract: Publication date: Available online 10 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): James B. Innes, Yongqiang Zong, Haixian Xiong, Zhanghua Wang, Zhongyuan Chen The coastal deltaic plain of the Yangtze River between Taihu (Lake Tai) and Shanghai in eastern China has been the scene of human settlement and agriculture since the early Neolithic, becoming increasingly intensive in the Upper Holocene when delta accretion and the establishment of a stable hydrological regime of freshwater lakes and wetlands allowed the development of extensive agriculture and complex society in late prehistoric and dynastic times. During this period the area was significantly affected by changes in sea level, climate and vegetation, resulting in a dynamic and complex environmental history, however little research has concentrated on environmental change and human impacts during the last few millennia. This study focuses on this late period, presenting the results of integrated sedimentary, microfossil and radiocarbon analyses from a core near the eastern margin of Lake Dianshan, to the east of Taihu. After the withdrawal of intertidal conditions and the conversion to freshwater lake at the core site about 2600 cal. yr BP, pollen and algal spore data show that increased sedimentation gradually reduced freshwater depth until a surface peat formed ca. 1500 cal yr BP. This also dates the start of a switch in woodlands from sub-tropical and warm temperate trees to a mainly cool temperate and coniferous tree flora, under climatic cooling and human impact. After this time water depths at the site increased greatly, partly due to climate change and flooding, but also because of the establishment of deepwater ‘paddy’ agriculture. Microcharcoal and pollen data show that a major episode of human impact using fire, with deforestation and rice cultivation, occurred between ca. 1500 and 1200 cal yr BP. These dates suggest it is one of the latest examples of ‘floodedfield’ ‘paddy’ cultivation before more intensive agricultural techniques were adopted in the area after ca. 800 cal. yr BP.
  • Isotopic variation within Tasmanian bare-nosed wombat tooth enamel:
           Implications for archaeological and palaeoecological research
    • Abstract: Publication date: Available online 10 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Georgia L. Roberts, Jacqueline Towers, Michael K. Gagan, Richard Cosgrove, Colin Smith Archaeologists and palaeoecologists are increasingly turning to stable isotope analysis (δ13C, δ18O) of fossil bioapatite to examine interactions of human and animal populations. However, relatively few investigations have focussed on the identification of natural variation in comparable modern populations, particularly within the Australian context. In this paper, we present the first modern isotopic reference dataset for Tasmanian bare-nosed wombat teeth (Vombatus ursinus tasmaniensis).Samples for δ13Cbioapatite and δ18Obioapatite measurements were recovered sequentially at sub-monthly resolution from all tooth types. δ13Cbioapatite showed little variation within a seasonal sinusoidal pattern within the sample set (n = 24 wombats; 35 teeth) due to the homogeneous C3 distribution of plants in Tasmania. In contrast, δ18Obioapatite profiles varied seasonally, representing time periods of between 0.9 and 2.1 years in 95% of the sample.Significant differences between tooth types were found from intra-individual to inter-regional scales for both dental growth rates and isotopic values. The accuracy of season-of-death assessments differed across the island; those in eastern Tasmania were accurate in all instances whereas those in the west showed substantial inaccuracies. We suggest that this may be due to the elodont form of wombat dentition and the ecologically influenced seasonally varied diet in western Tasmania. As the rate of dental growth is positively correlated with the proportion of coarse vegetation within the diet, this seasonal variation is therefore likely to change how annual isotopic signals are incorporated into the enamel. These results highlight the need to understand the degree of species-specific isotopic variation at a range of scales before applying this technique to archaeological or palaeontological assemblages.
  • Environmental influences on the stable carbon isotopic composition of
           Devonian and Early Carboniferous land plants
    • Abstract: Publication date: Available online 6 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Zhenzhu Wan, Thomas J. Algeo, Patricia G. Gensel, Stephen E. Scheckler, William E. Stein, Walter L. Cressler, Christopher M. Berry, Honghe Xu, Harold D. Rowe, Peter E. Sauer Systematic analysis of the stable carbon isotopic composition of fossil land plants (δ13Cp) has the potential to offer new insights regarding paleoclimate variation and plant-environment interactions in early terrestrial ecosystems. δ13Cp was measured for 190 fossil plant specimens belonging to 10 genera of Early to Late Devonian age (Archaeopteris, Drepanophycus, Haskinsia, Leclercqia, Pertica, Psilophyton, Rhacophyton, Sawdonia, Tetraxylopteris, and Wattieza) and 2 genera of Early Carboniferous age (Genselia and Rhodeopteridium) collected from sites located mainly in the Appalachian Basin (22–30°S paleolatitude). For the full carbon-isotopic dataset (n = 309), δ13Cp ranges from −20.3‰ to −30.5‰ with a mean of −25.5‰, similar to values for modern C3 land plants. In addition to a secular trend, δ13Cp exhibits both intra- and intergeneric variation. Intrageneric variation is expressed as a small (mean 0.45‰) 13C-enrichment of leaves and spines relative to stems that may reflect differential compound-specific compositions. Intergeneric variation is expressed as a much larger (to ~5‰) spread in the mean δ13Cp values of coeval plant genera that was probably controlled by taxon-specific habitat preferences and local environmental humidity. Among Early Devonian taxa, Sawdonia yielded the most 13C-depleted values (−27.1 ± 1.7‰), reflecting lower water-use efficiency that was probably related to growth in wetter habitats, and Leclercqia, Haskinsia, and Psilophyton yielded the most 13C-enriched values (−23.0 ± 1.6‰, −22.3 ± 1.3‰, and −24.8 ± 1.6‰, respectively), reflecting higher water-use efficiency probably related to growth in drier habitats.
  • Conodonts from Late Devonian island arc settings (Baruunhuurai Terrane,
           western Mongolia)
    • Abstract: Publication date: Available online 5 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): T.J. Suttner, E. Kido, Ya. Ariunchimeg, G. Sersmaa, J.A. Waters, S.K. Carmichael, C.J. Batchelor, M. Ariuntogos, A. Hušková, L. Slavík, J.I. Valenzuela-Ríos, J.-C. Liao, Y.A. Gatovsky Upper Devonian marine deposits of the Baruunhuurai Terrane in western Mongolia represent island arc settings, which yielded a diverse conodont assemblage of 30 taxa, including species of Ancyrognathus (as well as one new species), Icriodus, Mehlina, Polygnathus and Palmatolepis. Biodiversity analysis of Ancyrognathus, Pelekysgnathus, Mehlina and Icriodus shows that the Mongolian conodont assemblage consists of two endemic and few cosmopolitan taxa. Representatives of the otherwise globally distributed genus Pelekysgnathus are absent. An important factor influencing the regional distribution of conodont taxa seems to be the siliciclastic-dominated sedimentation of the Baruunhuurai Terrane during the early Famennian.
  • Paleoclimatic evolution of the SW and NE South China Sea and its
           relationship with spectral reflectance data over various age scales
    • Abstract: Publication date: Available online 2 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Chang Liu, Peter D. Clift, Liviu Giosan, Yunfa Miao, Sophie Warny, Shiming Wan Spectral analysis of sediment from International Ocean Discovery Program (IODP) Site U1433 in the South China Sea can be used to constrain humidity and temperature through time by constructing hematite/goethite records spanning the last 10 million years. Records in the southwest and northern parts of this basin show long-term contrasting trends, despite the fact that geochemical evidence for alteration is similar in both parts of the basin, i.e. towards less alteration since 10 Ma. However, contrasting clay mineral assemblages in the northern and southwestern areas do suggest long-term changes in the relative climate of Indochina and southern China. We interpret this to reflect the northward migration of the ITCZ since the Miocene resulting in a progressive drying of Indochina and increasingly wet conditions in South China. Sediment believed to be supplied from the Mekong River (IODP Site U1433) shows increasing chemical weathering at a time of long-term drying of the climate. This probably reflects increasing chemical weathering driven by slower transport and despite reduced rates of chemical alteration in the context of a colder, drier climate since the Miocene. In general hematite/goethite data are consistent with pollen constraints from the same drill site that show colder conditions with increasing hematite/goethite since 3 Ma and with a transition to apparently wetter conditions since the mid-Pleistocene transition (MPT). This implies that most of the sediment in the southwestern basin is weathered and eroded during warmer, wetter interglacial phases, at least since the MPT.
  • Impacts of climate-ocean-tectonic changes on early Paleozoic conodont
           ecology and evolution evidenced by the Canadian part of Laurentia
    • Abstract: Publication date: Available online 1 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Christopher R. Barnes In the Canadian part of Laurentia, large systematic conodont collections were assembled by many specialists over recent decades primarily for lower Paleozoic biostratigraphy, with some having sampling strategies to test ecologic hypotheses. The Laurentian plate straddled the paleoequator and accumulated extensive carbonate deposits, amenable to conodont recovery. In particular, the glaciated and mountainous Canadian part of Laurentia has permitted extensive collections through well-exposed shelf-to-basin transects across continental margins of the Appalachian, Cordilleran and Innuitian (Arctic) orogens, as well as intracratonic sedimentary basins and foreland basins affected by tectonism. From these remarkable settings, integrated studies by specialists of biostratigraphy, evolution, paleoecology, and paleobiogeography, together with oxygen, strontium and neodymium isotope analyses of conodont hard tissues, have involved nearly 700,000 conodonts from over 8000 samples from relatively undeformed stratigraphic sections. The results, with stratigraphic and sedimentologic data, have enabled interpretations of early Paleozoic climatic, oceanographic and eustatic changes and effects of tectonism.The late Cambrian-Early Ordovician exhibits the origin of euconodonts and initial diversification of coniform and ramiform apparatuses. By Middle Ordovician more complex apparatuses evolved with pectiniform (P) elements, with more complex community organization. Responses to sea-level changes can be tracked on both sides of the paleoequator from Cordilleran and Appalachian collections. Middle-Late Ordovician experienced extensive transgressive events, wider carbonate platforms, and the paleogeographic influence of residual Precambrian basement highs that partitioned conodonts into subprovinces. Restricted circulation and hypersalinity in these epeiric seas fostered specialized inshore communities with neurodonts and rhipidognathids. Terminal Ordovician mass extinction event (Gondwanan glaciation) affected forms with elaborate apparatuses whereas many coniform species survived. Slow radiation within the early Rhuddanian (early Silurian) produced community restructuring followed by progressive diversity increase punctuated by minor extinctions, some related to Gondwanan glacial re-advances. Oxygen isotopes show brief paleotemperature perturbations correlated to named episodes and events. Post-Rhuddanian conodont communities were well-defined, laterally segregated, with weak provincialism, and affected by oceanographic events and cratonic amalgamation with closure of the Iapetus Ocean and docking of Baltica, Avalonia and Pearya against Laurentia.
  • Conodonts across the Silurian/Devonian boundary in the Carnic Alps
           (Austria and Italy)
    • Abstract: Publication date: Available online 1 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Carlo Corradini, Maria G. Corriga, Monica Pondrelli, Thomas J. Suttner In the Carnic Alps, located across the border between Italy and Austria, several sections span the Silurian/Devonian boundary in different sedimentary settings, from very shallow water to moderately deep shelf. All studied sections yielded conodonts and based on the first and last occurrences of the conodont taxa in the upper part of the Upper Oul. el. detortus Zone and in the lower part of the I. hesperius Zone a detailed conodont biostratigraphic framework was able to be constructed for this interval. Comparison of data from different depositional settings demonstrates that, although the majority of species are documented everywhere in the Carnic basin, a few taxa, mainly represented by coniforms, are limited to shallow water, whereas others, mainly ozarkodinids, occur only in open sea deposits.Graphical abstractUnlabelled Image
  • Mineralogy and crystallization patterns in conodont bioapatite from first
           occurrence (Cambrian) to extinction (end-Triassic)
    • Abstract: Publication date: Available online 1 March 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Luca Medici, Daniele Malferrari, Martina Savioli, Annalisa Ferretti Bioapatite represents an important acquisition in the evolution of life, both in the seas and on land. Vertebrates applied calcium-phosphate biominerals to grow their skeletal support and to shape their teeth, while some invertebrates sheltered their soft parts within apatite shells. Conodonts were the first among vertebrates to experiment with skeletal biomineralization of tooth-like elements in their feeding apparatus. Spanning a time record of over 300 million years, they offer a unique tool to test possible variation in bioapatite structure from the experimentation of a very primitive biomineralization type to a more evolute pattern just before going extinct. X-ray microdiffraction carried out through an X-ray micro-diffractometer, integrated with environmental scanning electron microscopy coupled with chemical microanalyses (ESEM-EDX), has been applied in this study to investigate conodont element crystal structure throughout the entire stratigraphic range of these organisms. In particular, bioapatite crystallographic cell parameters have been calculated for about one hundred conodont elements ranging from the late Cambrian to the Late Triassic. Resulting data clearly indicate two distinct distribution plots of cell parameters for paraconodonts and euconodonts. In contrast, age, taxonomy, geographic provenance and CAI do not affect the dimension of the bioapatite crystal cells. Conodont bioapatite crystallographic cell parameters have been compared with cell parameters resulting from phosphatic/phosphatized material (ostracodes, brachiopods, bryozoans, and fish teeth) present in the same residues producing conodonts. Resulting values of the cell parameters are, in general, mainly correlated with the type of organisms even if, for some of them, a correlation also with age cannot be completely ruled out. According to our data, primary bioapatite appears to imprint a key signature on fossil crystal-chemistry (crystal structure and major chemical element contents), while the contribution of fossilization and diagenetic processes seems less relevant.Graphical abstractUnlabelled Image
  • P1 element morphological variability within the Late Pennsylvanian
           asymmetrical Idiognathodus clade from the Midcontinent, U.S.A. and
           implications for ontogeny, taxonomy, phylogeny, and function
    • Abstract: Publication date: Available online 28 February 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Nicholas J. Hogancamp Missourian-Virgilian asymmetrical Idiognathodus represent a distinct clade of species with strong dextral-sinistral P1 element asymmetry that exhibit a series of morphological events before the Late Pennsylvanian extinction of Idiognathodus. Previous taxonomic work and morphometric analyses were completed separately for the three major groups of the clade. From oldest to youngest, these are the I. magnificus, I. eudoraensis, and I. simulator groups. The dextral-sinistral P1 element asymmetry is more apparent in larger specimens and the asymmetry is caused by ontogenetic distortion of the dextral element, which widens in the ventral part of the rostral side. At smaller sizes, both sinistral and dextral elements grow predominately dorsal-ventral, and at larger sizes growth is predominately rostral-caudal. Lobe groups correspond with different platform shapes, suggesting that lobe groups are useful taxonomic identification criterion for classifying morphologically distinct species.There are four major morphological events that occur within the asymmetrical Idiognathodus clade: 1) the development of simulator-style P1 element asymmetry in the I. magnificus group; 2) the replacement of flat ungrooved platforms in the I. magnificus group with the grooved platforms of the I. eudoraensis group; 3) the shortening of the adcarinal ridges and development of stronger dextral-sinistral element P1 asymmetry in the I. simulator group; and 4) the replacement of the asymmetric Idiognathodus clade with the I. tersus group which have grooveless narrow platforms, long adcarinal ridges and no apparent dextral-sinistral P1 element asymmetry. These morphological events likely reflect significant biological and paleoecological changes that ultimately culminate with the extinction of Idiognathodus.
  • Corrigendum to “Nitrogen isotope and trace element composition
           characteristics of the Lower Cambrian Niutitang Formation shale in the
           upper -middle Yangtze region, South China” [Palaeogeogr. Palaeoclimatol.
           Palaeoecol. 501 (2018) 1–12]
    • Abstract: Publication date: Available online 19 February 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Min Li, Jianfa Chen, Tieguan Wang, Ningning Zhong, Shengbao Shi
  • Corrigendum to “Millennial scale climate oscillations recorded in the
           Lower Danube loess over the last glacial period” [Palaeogeogr.
           Palaeoclimatol. Palaeoecol. 509, 15 November 2018 164–181]
    • Abstract: Publication date: Available online 10 February 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Christian Zeeden, Ulrich Hambach, Daniel Veres, Kathryn Fitzsimmons, Igor Obreht, Janina Bösken, Frank Lehmkuhl
  • Exceptional basal-body preservation in some Early Triassic conodont
           elements from Oman
    • Abstract: Publication date: Available online 29 January 2019Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Louise Souquet, Nicolas Goudemand Conodont elements are composed of two main parts: the crown and the basal body. The basal body of a conodont element is a laminated structure that is less densely mineralized than the crown and, as a result, is rarely preserved. Elements with preserved basal bodies are found only in exceptional cases in the fossil record. To date, no S or M element with preserved basal body has ever been documented for post-Devonian conodonts, which had raised the question of an evolutionary trend towards unmineralized basal bodies in conodonts. Here we report the discovery, in Smithian (Early Triassic) rocks of Oman, of neospathodid conodont elements whose basal body is partly preserved. We demonstrate the presence of basal body in all elements, including S and M elements, of Novispathodus, and most likely of all gondolelloideans, thereby suggesting that the absence of basal bodies in post-Devonian conodonts was due to a preservational bias only. We further demonstrate that the morphology and extent of the basal bodies in Novispathodus are in agreement with previous predictions and do not contradict a cyclostome-like functional model of the apparatus. Based on a review of the occurrences of basal bodies in the literature, we suggest a general pattern for the morphology of the basal bodies in conodont elements that may reflect the mechanical constraints associated with feeding motions.
  • Circulation patterns in the Late Pennsylvanian North American Midcontinent
           Sea inferred from spatial gradients in sediment chemistry and mineralogy
    • Abstract: Publication date: Available online 17 December 2018Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Adam C.E. Turner, Thomas J. Algeo, Yongbo Peng, Achim D. Herrmann The North American Midcontinent Sea (NAMS) reached its maximum extent during glacio-eustatic highstands of the Late Paleozoic Ice Age, during which organic-rich “core shales” accumulated under a stratified water column with anoxic deep waters. The core shales of cyclothems are composed of a lower organic-rich laminated black shale and an upper bioturbated gray shale. The present study investigates circulation patterns within the NAMS by examining secular variations and spatial gradients in the concentrations and ratios of major elements, trace elements, and organic carbon, as well as carbon and nitrogen isotopes, within one cyclothemic core shale: the Heebner Shale. The Heebner Shale represents the core shale member of the Upper Pennsylvanian (lowermost Gzhelian; Virgilian) Oread Limestone Formation in Kansas and Iowa, and it is correlative with the Teutopolis Shale of the Mattoon Formation in Illinois. The Heebner was sampled at high stratigraphic resolution at five sites on the northern Midcontinent Shelf and two sites in the Illinois Basin. Clay and silt fraction proxies show influences from multiple distinct terrestrial sources. The paleosalinity proxy Sr/Ba in combination with spatial patterns of clay and silt proxies implies large-scale counterclockwise (cyclonic) rotation of the NAMS watermass, which was possibly driven by the hydrodynamics of upwelling on the southern Midcontinent Shelf margin and/or riverine discharge into the eastern NAMS. Spatial patterns of δ13C and δ15N are consistent with regionally variable productivity and redox conditions. Differences in the magnitude of a positive δ15N excursion among the study sites record spatially variable water-column denitrification rates. Enrichment of trace metals on the northern Midcontinent Shelf was a product of intensified water-column recycling within an estuarine saltwater wedge. Trace-metal enrichments and Fe/Al ratios are consistent with moderate watermass restriction throughout the NAMS. The results of the present study permit major refinement of the existing superestuarine circulation model for the NAMS [Algeo, T.J., et al., 2008, Modern and ancient epeiric seas and the super-estuarine circulation model of marine anoxia. In: B. Pratt and C. Holmden (eds.), Dynamics of Epeiric Seas, Geol. Assoc. Canada Spec. Publ. 48, pp. 7–38].
  • Discovery of Lower Devonian plants from Jiangxi, South China and the
           pattern of Devonian transgression after the Kwangsian Orogeny in the
           Cathaysia Block
    • Abstract: Publication date: Available online 13 November 2018Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Hong-He Xu, Yi Wang, Peng Tang, Qiang Fu, Yao Wang The Kwangsian Orogeny is a major geological event in the Paleozoic of South China and has been debated with data of lithofacies, biofacies, palaeogeography and geodynamics. However, the transgression after the Kwangsian Orogeny has been less concerned. In this study, Early Devonian plants, including a basal euphyllophyte plant attributed to Pauthecophyton sp., are discovered for the first time from the Yangling Psephyte, Chongyi, Jiangxi Province, China, which palaeogeographically belongs to the Cathaysia Block of the South China Plate. Based on the presence of these plant fossils, the Yangling Psephyte is dated as Pragian (Early Devonian). Combined with 23 horizons and 52 Devonian plant fossil localities in southern China reported in previous studies, the transgression and deposition pattern after the Kwangsian Orogeny is recognized. It is indicated that in the Cathaysia Block the transgression and deposition after the Kwangsian Orogeny was stepwise, started not later than the Pragian Stage, continued until at least the Late Devonian and gradually strengthened northeastwards from the Early Devonian to the Late Devonian.
  • Intensified oceanic circulation during Early Carboniferous cooling events:
           Evidence from carbon and nitrogen isotopes
    • Abstract: Publication date: Available online 24 October 2018Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Jiangsi Liu, Thomas J. Algeo, Wenkun Qie, Matthew R. Saltzman The Early Carboniferous was a climatic transition interval from a mid-Paleozoic greenhouse world into the Late Paleozoic Ice Age. It was marked by a long-term cooling trend that was punctuated by short glaciations in the Tournaisian and Visean (early to mid-Early Carboniferous). Here, we generated organic carbon and nitrogen isotope profiles for two widely separated Lower Carboniferous sections (Arrow Canyon Range, Nevada, and Namur-Dinant Basin, Belgium) in order to assess the global nature and timing of changes in the carbon‑nitrogen cycles linked to oceanic productivity and redox conditions during this climatic transition interval. The carbon and nitrogen isotope profiles of both study sections record major perturbations during the mid-Tournaisian and Visean. A mid-Tournaisian event (TICE) is marked by increases in δ13Ccarb, δ13Corg, and δ15Nbulk at Arrow Canyon (from +0.6 to +7.0‰, −25.2 to −23.7‰, and –0.6 to +8.9‰, respectively) and Namur-Dinant (from −0.3 to +4.7‰, −27.9‰ to −22.2‰, and –5.7 to +5.2‰, respectively). An early Visean event (VICE; named herein) is marked by increases in δ13Ccarb, δ13Corg, and δ15Nbulk at Arrow Canyon (from −0.6 to +3.1‰, −28.4 to −23.6‰, and +1.4 to +9.4‰, respectively) and Namur-Dinant (from +2.1 to +4.3‰, −26.7 to −25.0‰, and –1.4 to +3.3‰, respectively). The positive excursions in all three isotopic records during these events are consistent with increased fractional burial of organic carbon and enhanced denitrification, implying intensification of marine productivity and expansion of hypoxia in the global ocean. Given that each event coincided with lowering of sea-surface temperatures and increased glaciation (as documented from published conodont δ18O and sea-level records), we hypothesize that global cooling led to intensified oceanic circulation and upwelling on continental margins, triggering increased marine productivity and attendant redox changes within the affected upwelling zones. Our results provide new insights into changes in Early Carboniferous oceanic conditions in response to the initial stages of cooling leading into the Late Paleozoic Ice Age.
  • Warm-water carbonates in proximity to Gondwanan ice–sheets: A record
           from the Upper Paleozoic of Iran
    • Abstract: Publication date: Available online 12 September 2018Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Mehrdad Sardar Abadi, Gerilyn S. Soreghan, Nicholas G. Heavens, Dennis F.A.E. Voeten, Rimma M. Ivanova Sedimentologic and paleontologic proxies recovered from the Alborz Basin, the Sanandaj – Sirjan Zone, and additional Iranian peri–Gondwanan continental blocks near the Arabian margin of northeastern Gondwana record the formation of warm-water, shallow-marine carbonates throughout the Late Pennsylvanian – earliest Permian. This reflects a prevailing favorable climatic and environmental regime that contrasts with the cold conditions of slightly more southerly Gondwanan regions that experienced profound glaciations. The sedimentologic and paleobiologic properties of these Iranian carbonates also differ greatly from coeval cool-water carbonates of Bolivia that developed at equivalent paleolatitudes along the northwestern margin of Gondwana. The complex climatic patterns reflected in the dispersal of marine taxa and their colonization of ecosystems relatively remote to their customary habitats and climate zones are interpreted to record the influence of ocean circulation. Based on these sedimentologic and paleobiologic data, we utilized a climate model (Community Climate System Model Version 3 (CCSM3)) to help resolve the mechanisms responsible for enabling transport of warm water to higher latitudes in northeastern Gondwana. These simulations reveal that spatial variations in sea surface temperatures exerted a strong forcing on Paleo-Tethyan oceanic circulation and thereby governed the distribution, diversity, and abundance of taxa in late Paleozoic marine ecosystems. Based on this outcome, we conclude that the climatic contrasts registered across Upper Pennsylvanian – Lower Permian carbonate platforms of the Paleo-Tethys and Panthalassic Ocean originated through oceanic circulation driven by geographic differences in sea surface temperature.
  • Biomarker signatures of the iconic Glossopteris plant
    • Abstract: Publication date: Available online 3 August 2018Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Anuradha Tewari, Ashalata D'Rozario, Sharmila Bhattacharya, Ahinsuk Barua, Meghma Bera, Subir Bera, Suryendu Dutta Glossopteris is the quintessential marker plant that dominated the forests of the Southern Hemisphere continents during the Permian before their abrupt extinction at the close of the Palaeozoic. Fossilized leaf and stem remains of Glossopteris plants, collected from the Permian succession of eastern India, were analysed to recognize the molecular signatures of solvent-extractable and non-extractable organic matter. Lipid-derived aliphatic and aromatic biomarkers were studied using GC–MS and GC×GC-TOFMS, while tetramethylammonium hydroxide (TMAH) thermochemolysis with GC–MS and GC×GC-TOFMS was used to reveal lignin precursors. The thermal maturity indices indicate low thermal rank for both samples. The presence of aromatic diterpanes in the leaf extract suggests that the Glossopteris plant was able to biosynthesize abietic acid and related plant terpenoids. The thermochemolysis products (thermochemolysates) of the samples contain monomethoxy-, and dimethoxybenzene derivatives produced from p‑hydroxyphenyl and guaiacyl units of lignin, respectively, which are the main constituents of extant gymnosperm lignin. The thermochemolysates indicate that lignin biosynthesis had evolved in Glossopteris.
  • Late Mississippian glacio-eustasy recorded in the eastern Paleo-Tethys
           Ocean (South China)
    • Abstract: Publication date: Available online 25 July 2018Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Jitao Chen, Qingyi Sheng, Keyi Hu, Le Yao, Wei Lin, Isabel P. Montañez, Xiaoxu Tian, Yuping Qi, Xiangdong Wang Long-lived and extensive glaciation during the Carboniferous and early Permian has been the focus of many studies over the past decade revealing systematic changes in sea level and climatic conditions. The nature of the inception of Carboniferous glaciation, however, remains poorly resolved with uncertainty regarding the timing and dynamics of buildup of continental ice sheets. Here we present detailed sedimentary facies and depositional cycles from Upper Mississippian shallow-water platform and contemporaneous carbonate slope successions from the eastern Paleo-Tethys Ocean region (South China) to reveal systematic variations that provide insight into the sedimentary response to the onset of Carboniferous glaciation. Based on detailed sedimentological logging and facies analysis, four upper Visean cycles and four Serpukhovian cycles were identified from the carbonate platform Yashui section, bounded by either subaerial surfaces or zones, or transgressive surfaces. The cycle tops roughly correspond to intervals rich in normally graded bioclastic wacke- to packstones and with distinct rises (~1‰) in conodont δ18OPO4 in the carbonate slope Naqing section. In particular, the four Serpukhovian cycles correlate well to depositional cycles defined in the Lower Yangtze Platform succession of South China and in the cyclothemic successions in the Donets Basin, Ukraine, suggesting a glacio-eustatic control, most likely caused by repeated advance and retreat of Gondwana glaciation during the onset but prior to widespread glaciation across the mid-Carboniferous boundary.
  • Gondolelloid multielement conodont apparatus (Nicoraella) from the Middle
           Triassic of Yunnan Province, southwestern China
    • Abstract: Publication date: Available online 20 July 2018Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Jinyuan Huang, Shixue Hu, Qiyue Zhang, Philip C.J. Donoghue, Michael J. Benton, Changyong Zhou, Carlos Martínez-Pérez, Wen Wen, Tao Xie, Zhong-Qiang Chen, Mao Luo, Huazhou Yao, Kexin Zhang The morphology and position of elements in the apparatus are keys to resolving the taxonomy, homology, evolutionary relationships, structure, function and feeding patterns among conodont taxa. Fused clusters preserving natural associations between elements provide direct information on element morphology, the positions of elements within the apparatus, and even their original three-dimensional arrangement. Here, we report 41 fused conodont clusters from Member II of the Guanling Formation in Luoping County, Yunnan Province, southwestern China, which provide a basis for inferring the multielement composition of the apparatus of the early Middle Triassic Nicoraella. The apparatus is composed of 15 elements (a single S0 element, two pairs of S1–4, M and P1–2 elements) like other apparatuses in Gondolellidae, i.e. the genera Novispathodus and Neogondolella. These Luoping Biota clusters are significant because (a) they permit a positional homology-based comparison of multielement Novispathodus with form genera such as Cypridodella (S1), Enantiognathus (S2), and Hindeodella (S3 and S4), (b) they facilitate a review of apparatus composition within superfamily Gondolelloidea, (c) they provide direct insight into apparatus architecture currently interpreted largely in light of distantly related Carboniferous polygnathacean ozarkodinins, and (d) these clusters, along with collections of discrete conodont elements, provide a model for inferring the multielement composition of closely related species known only from discrete element collections.
  • Paleogeographic differences in temperature, water depth and conodont
           biofacies during the Late Devonian
    • Abstract: Publication date: Available online 4 July 2018Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Catherine Girard, Jean-Jacques Cornée, Michael M. Joachimski, Anne-Lise Charruault, Anne-Béatrice Dufour, Sabrina Renaud The Famennian (Late Devonian) started after and ended with two of the seven largest crises of the Phanerozoic, the Kellwasser and Hangenberg events, respectively. In between, global environmental trends have been identified, involving cooling and eustatic regression. Tropical and subtropical marine faunas were largely cosmopolitan. Overall, this suggests that the Famennian was marked by long-term environmental changes occurring in a relatively homogeneous manner despite being punctuated by several short-term events of limited faunal impact. How these trends were modulated according to geographic location is investigated in this study by comparing two continuous outcrops in the Montagne Noire (Col des Tribes section, France) and in Saxo-Thuringia (Buschteich section, Germany). Both were located in the subtropical area during this period and belonged to two former microcontinents bracketed between the closing Rheic Ocean and Gondwana. Sedimentary facies, oxygen isotopes, and the generic conodont composition (biofacies) were studied in a high resolution and in the same rock samples. Sedimentary facies provided an estimate of water depth and oxygen isotopes were used as paleotemperature proxy. Conodont biofacies were analyzed using a principal component analysis, allowing the expression of the variations in the two outcrops on the same axes, and a quantitative comparison with the other proxies. Sea-level and temperature variations were different between the two areas. Saxo-Thuringia displayed stable deep and warm conditions throughout. In contrast, the environment of the Montagne Noire was shallower and cooler during the Late and latest Famennian compared to the Early and Middle Famennian, congruent with the global change evidenced elsewhere. The location of Saxo-Thuringia, close to the first point of closure of the Rheic Ocean, might have favored active tectonics, causing a local departure from the eustatic trend. The stable temperatures at BU during the Late and latest Famennian may be due to the position of Saxo-Thuringia in the remnant Rheic Ocean, limiting water mass exchange with open seas, and favoring the persistence of warm conditions.Offshore taxa persisted later at high abundance in the Saxo-Thuringian record. The two conodont biofacies records were otherwise very comparable. This suggests that other factors mitigated the water depth forcing on these conodont assemblages.
  • Revised perspectives on Devonian biozonation and environmental volatility
           in the wake of recent time-scale revisions
    • Abstract: Publication date: Available online 26 June 2018Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Carlton E. Brett, James J. Zambito, Patrick I. McLaughlin, Poul Emsbo Revised time-scales for the Devonian Period have highlighted major discrepancies in the frequency of evolutionary, eustatic, carbon cycle, and biotic events. The number of conodont biozones per million years shows strong variation among stages. Using two alternative time scales, the lowest values are in the Emsian and highest in the Givetian, Frasnian, and Famennian stages. A similar result is obtained by dividing the Devonian time scale into 12 equal 5-million year bins and determining the number of conodont zonal subdivisions in each bin. The record of ammonoid biozones also shows interesting parallels. The acuity of biostratigraphic zonation and zonal subdivisions appears to be correlative with the frequency of environmental perturbations, including eustatic, positive carbon isotopic excursions, and hypoxic/anoxic related bioevents, and these are similarly unevenly distributed. All calculations of environmental volatility metrics show the late Eifelian through early Frasnian to be the most volatile interval of the Devonian, followed by the mid-late Famennian, while the Lochkovian through Emsian and mid-Frasnian through early Famennian are the least volatile. Furthermore, the majority of major bioevents occur in the Eifelian through early Frasnian, and late Famennian.The strong evidence for higher biotic and environmental volatility in the late Eifelian through early Frasnian and late Famennian rock record corresponds to the coolest paleoclimate conditions in the Devonian according to recent conodont apatite δ18O compilations, and the transition from an overall cooling to warming paleotemperature trend during the mid-Givetian. Regardless of mechanism, strong variations in volatility occurred during the Devonian Period. Intervals with greater biostratigraphic resolution also show much stronger environmental volatility including a series of relatively quasi-stable conditions punctuated by major turnovers with abrupt sea-level rise, widespread hypoxia, and changes in the carbon cycle. It was during these intervals that much net evolutionary and ecological change appears to have taken place.
  • Biogeochemical controls on black shale deposition during the
           Frasnian-Famennian biotic crisis in the Illinois and Appalachian Basins,
           USA, inferred from stable isotopes of nitrogen and carbon
    • Abstract: Publication date: Available online 24 May 2018Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Benjamin T. Uveges, Christopher K. Junium, Diana L. Boyer, Phoebe A. Cohen, James E. Day The Frasnian-Famennian biotic crisis is marked by two distinct intervals known as the Lower and Upper Kellwasser Events (KWEs) that in many locations are associated with deposition of organic-rich shales. Sedimentary nitrogen and carbon isotopes offer insight into the biogeochemical processing of nutrients, production of organic matter, and palaeoceanographic conditions during the KWEs. Here we present new bulk nitrogen (δ15Nbulk) and organic carbon (δ13Corg) isotope data from the Late Devonian Appalachian and Illinois Basins (AB and IB), with a focus on intervals encompassing the KWEs. Black shales from the IB and AB, including the KWEs, are 15N-depleted (−1.0–+2.0‰) and have significantly lower δ15Nbulk than interbedded grey shales (+0.5–+4.0‰), a trend consistent with many instances of black shale deposition in the Phanerozoic. Organic carbon isotopes exhibit the broad, positive excursions (~+3.5‰ from background) that are typical of the KWEs globally. Superimposed over these positive excursions in δ13Corg are sharp decreases of up to ~3.0‰ within the black shale beds, to as low as −30.5‰. The pattern of δ15Nbulk and δ13Corg values suggests that the depth of the chemocline and the degree of water-column stratification exert a primary control on both δ15Nbulk and δ13Corg during black shale deposition. In the context of the Frasnian-Famennian biotic crisis, the oscillating redox state and changing temperatures would have likely placed extreme stress on organisms within the marine environment of the AB and IB and may potentially have been a contributing factor to diversity loss over this time period.
  • Isotopes to ice: Constraining provenance of glacial deposits and ice
           centers in west-central Gondwana
    • Abstract: Publication date: Available online 4 May 2018Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Neil Patrick Griffis, Isabel Patricia Montañez, Nicholas Fedorchuk, John Isbell, Roland Mundil, Fernando Vesely, Luiz Weinshultz, Roberto Iannuzzi, Erik Gulbranson, Arturo Taboada, Alejandra Pagani, Matthew Edward Sanborn, Magda Huyskens, Josh Wimpenny, Bastien Linol, Qing-Zhu Yin The timing and geographic distribution of glaciers in high-latitude southern Gondwana during the Late Paleozoic Ice Age remain poorly constrained, ultimately precluding our ability to estimate ice volume and associated climate teleconnections and feedbacks during Earth's penultimate icehouse. Current aerial extents of glaciers, constrained by sedimentary flow directions, near exclusively infer paleo-glaciation to be highland-driven and may underestimate potential ice sources in continental regions from which ice sheets may have emanated. Here, we report new U-Pb ages and Hf isotope compositions of detrital zircons recovered from diamictites in two key mid- to high-latitude Gondwanan basins (Paraná, Brazil and Tepuel, Argentine Patagonia). The results indicate regional sediment sources for both basins during the early period of late Paleozoic glaciation evolving into more distal sources during the final deglaciation along southern and western Gondwana. Similar age sediment sourced from diamictites in the Congo Basin, that require an ice center in eastern Africa suggest the possibility of a large ice sheet in this area of Africa proximal to the Carboniferous-Permian boundary, which may have sourced sediments to the Paraná Basin. An inferred distal southern source of glacial sediment for the Tepuel Basin argues for the presence of an ice sheet(s) in the Ellsworth Block of Antarctica towards the end of the glaciation history in Patagonia. These findings indicate an evolution during the Late Paleozoic Ice Age from proximally to extrabasinally sourced sediment reflecting continental-scale glaciation and subsequent drainage from the Windhoek Highlands, Ellsworth Block and an east African source in west-central Gondwana. Coincidence with a long-term fall in atmospheric pCO2 during the Pennsylvanian to a minimum across the Carboniferous-Permian boundary and a subsequent rise in the early Permian suggests a primary CO2-driver for deglaciation in the Paraná Basin. Additional boundary conditions including availability of moisture and paleogeography likely further contributed to the timing of nucleation, growth and demise of these Gondwanan glaciers.
  • Origin of paleovalleys on the Rio Grande do Sul Shield (Brazil):
           Implications for the extent of late Paleozoic glaciation in west-central
    • Abstract: Publication date: Available online 24 April 2018Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Nicholas D. Fedorchuk, John L. Isbell, Neil P. Griffis, Isabel P. Montañez, Fernando F. Vesely, Roberto Iannuzzi, Roland Mundil, Qing-Zhu Yin, Kathryn N. Pauls, Eduardo L.M. Rosa The location, longevity, and geographic extent of late Paleozoic ice centers in west-central Gondwana remain ambiguous. Paleovalleys on the Rio Grande do Sul Shield of southernmost Brazil have previously been interpreted as fjords carved by outlet glaciers that originated in Africa and emptied into the Paraná Basin (Brazil). In this study, the sedimentology, stratigraphy, and provenance of sediments infilling two such paleovalleys (the Mariana Pimentel and Leão paleovalleys) were examined in order to test the hypothesis that an ice center over present day Namibia drained across southernmost Brazil during the Carboniferous and Permian. Contrary to previous findings, the facies assemblage from within the paleovalleys is inconsistent with a fjord setting and no clear evidence for glaciation was observed. The facies show a transition from a non-glacial lacustrine/estuarine environment, to a fluvial-dominated setting, and finally to a restricted marine/estuarine environment. Detrital zircon results present a single population of Neoproterozoic ages (c. 800–550 Ma) from the paleovalley fill that matches the ages of underlying igneous and metamorphic basement (Dom Feliciano Belt) and is incongruent with African sources that contain abundant older (Mesoproterozoic, Paleoproterozoic, and Archean) zircons. Furthermore, results suggest that the formation of the paleovalleys and the deposition of their fill were controlled by the reactivation of Neoproterozoic basement structures during the Carboniferous and Permian. The lack of evidence for glaciation in these paleovalleys highlights the need for detailed studies of supposed late Paleozoic glacial deposits. These results are supportive of the hypothesis that well-established glacial sediments on the Rio Grande do Sul Shield (southern margin of the Paraná Basin) may be the product of a separate lobe extending north across Uruguay, rather than a single, massive ice sheet draining west from Africa.
  • Upper Viséan coral biostrome in a volcanic-sedimentary setting from the
           Eastern Tianshan, Northwest China
    • Abstract: Publication date: Available online 21 April 2018Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Xing Huang, Markus Aretz, Xionghua Zhang, Yuansheng Du, Tengfei Luan For the first time, a Mississippian coral biostrome is described from the Eastern Tianshan, Xinjiang Province, Northwest China. Rugose corals and foraminifers show that the biostrome developed during the late Viséan in one of the rare carbonate levels in the mainly volcanic-siliciclastic succession of the Yamansu Formation. A single fasciculate coral, Siphonodendron irregulare, dominates (>80%) this biostrome. Of the 22 coral genera found in the Yamansu Formation, 5 colonial and 6 solitary dissepimented corals are recorded in the biostrome. The biostrome can be divided vertically into two parts. In the main thick part dominate large patches of in situ Siphonodendron irregulare colonies. In the thinner uppermost part, Siphonodendron irregulare and Lithostrotion formed locally isolated small patches in a capping bed. The initial growth of the coral patches was related to slight topographic irregularities in the underlying volcano-sedimentary rocks. Siphonodendron irregulare appears to have been the best adapted species to the environmental pressures in the unstable tectono-sedimentary environment of the Yamansu Formation. It flourished and outnumbered the other corals when volcanic activity ceased and carbonate production became active for a short time. The development of the Siphonodendron biostrome ceased due to increases in sea-level and volcanic activity. Compared to Siphonodendron biostromes in the western and eastern Paleotethys, the Siphonodendron biostrome in Yamansu is unique for having developed in an island arc setting. To date, the Yamansu biostrome is the only documented coral bioconstruction at similar latitudes in the Central Asian Orogenic Belt (CAOB). Formation of this coral biostrome was controlled by extrinsic factors, such as changes in global climate and ocean currents, and intrinsic factors, such as the pioneering nature of the fast-growing Siphonodendron irregulare. Both sets of factors are responsible for the expansion of the tropical reef belt into previously more temperate environments.
  • Late Devonian palaeobiogeography of marine organic-walled phytoplankton
    • Abstract: Publication date: Available online 20 March 2018Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Zhen Shen, Junjun Song, Thomas Servais, Yiming Gong Acritarchs and prasinophytes have generally been considered as organic-walled phytoplankton, and their distribution patterns play a significant role in palaeogeographical and palaeoclimatical reconstructions. In this paper the palaeobiogeography of Late Devonian phytoplankton (mainly Famennian) is quantitatively analyzed based on a global database consisting of 95 genera from 15 geographical units. The data are analyzed using cluster analysis, nonmetric multidimensional scaling, and minimum spanning tree analysis using the Jaccard, Ochiai, Kulczynski, and Yule's Y similarity coefficients. The results show that there was provincialism in the Late Devonian and three phytoplankton palaeobiogeographical realms could be identified: the West Gondwana, East Gondwana, and Boreal realms. There is a high degree of similarity between phytoplankton assemblages in East Gondwana (especially those in Australia and Iran) and Euramerica. Portugal (of the Iberian-Armorican block) was situated to the north of Algeria and probably acted as a stepping stone between Euramerica and West Gondwana. The closed oceanic surface circulation pattern in the Proto-Tethys Ocean between Euramerica and East Gondwana might have hindered the exchange of phytoplankton between East and West Gondwana. The phytoplankton province that had been typically confined to the higher latitudes was still present, while its characteristic genera gradually dispersed into the lower latitudes in the Late Devonian. There is a high similarity between phytoplankton assemblages from the western Junggar of Xinjiang, NW China and Euramerica. Latitude- and current-influenced palaeotemperature and oceanic circulation patterns are considered to have been the major determinants of the geographical distribution and evolution of marine phytoplankton in the Late Devonian.
  • Palynostratigraphy of the Devonian–Carboniferous transition in the
           Tulong section in South Tibet: A Hangenberg Event sequence analogue in the
           Himalaya-Tethys zone
    • Abstract: Publication date: Available online 15 March 2018Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Feng Liu, Hans Kerp, Huiping Peng, Huaicheng Zhu, Jungang Peng Palynological assemblages from the Tulong succession in South Tibet enabled the recognition of three miospore biozones within the Zhangdong and ‘Yali’ formations. In ascending order, they are the Retispora lepidophyta–Verrucosisporites nitidus (LN) Biozone, the Vallatisporites vallatus–Foveosporites pellucidus (VP) Biozone and the Rugospora polyptycha–Tricidarisporites arcuatus (PA) Biozone. The LN Biozone in the Tulong section can be correlated to the LN Biozone of Western Europe, based on the first and last appearances of many index miospore species. However, Tournaisian palynological assemblages of Western Europe and South Tibet show compositional differences. The VP and PA biozones of South Tibet are correlated tentatively to the VI–HD and BP–TC biozones of Western Europe based on the occurrences of rare miospore index species in both regions. The Zhangdong and ‘Yali’ formations are now dated as Famennian to possibly earliest Visean. This age assessment is supported by rare conodonts and ammonoids recovered from intercalated limestones in the basal part of ‘Yali’ Formation. In the Everest region, the Devonian–Carboniferous boundary is now placed c. 10 m above the lower boundary of the ‘Yali’ Formation, which was originally suggested by Lin and Qiu (1985) to be position of the D–C boundary. Unlike western Gondwana, i.e. Bolivia and Brazil, the Himalaya-Tethys zone at the northeastern margin of Gondwana does not show obvious lithological evidence for glaciations. The new palynostratigraphic data, including information on sea-level changes reflected by variations in palynological composition and lithology around the Devonian–Carboniferous boundary allow, an interregional, approximate correlation with the classical Hangenberg Event sequence in the Rhenish Massif. The analogous Hangenberg Event sequence in South Tibet further supports the hypothesis that the rapid Hangenberg Event regression/transgression was a global eustatic event of significant magnitude. The co-occurrence of probably reworked Frasnian Geminospora lemurata and Archaeoperisaccus spores in the Himalaya-Tethys zone indicates the palaeogeographical proximity of the northern margin of Gondwana to the South China Block in the palaeoequatorial belt.
  • Development of a high-productivity and anoxic-euxinic condition during the
           late Guadalupian in the Lower Yangtze region: Implications for the
           mid-Capitanian extinction event
    • Abstract: Publication date: Available online 31 January 2018Source: Palaeogeography, Palaeoclimatology, PalaeoecologyAuthor(s): Bolin Zhang, Suping Yao, Wenxuan Hu, Hai Ding, Biao Liu, Yongle Ren Widespread marine anoxia is considered one of the most important causes for the mid-Capitanian mass extinction. However, the mechanisms and subsequent sulfidic process for the mid-Capitanian mass extinction are still debated. Here, we focus on a comprehensive study including marine productivity and redox conditions of the Lower Yangtze area across the mid-Capitanian mass extinction based on multiple geochemical indicators. Our results show that the redox conditions and marine productivity have gone through three stages. The pre-extinction early-middle Capitanian is characterized by anoxic conditions with intermittent euxinic episodes and moderate-high productivity, whereas the middle Capitanian is dominated by stronger euxinic conditions and higher productivity. Subsequently, an oxic shallow water environment and low productivity are recognized by significant decreases in all of these geochemical indicators across the mid-Capitanian. The appearance and development of the anoxic-euxinic conditions was probably caused by high productivity related to enhanced upwelling, which led to the intensified heterotrophic respiration and subsequent oxygen-depletion of the water column. More sluggish oceanic circulation that resulted from the global warming associated with the eruption of the Emeishan Large Igneous Province and upward movement of the chemocline due to great regression also further exacerbated the euxinic conditions during the middle Capitanian. The development of these euxinic conditions may have played a major role in triggering the super-anoxic ocean and is also coincident with the mid-Capitanian biotic crisis, which suggests the possible causal link between them. With comprehensive analysis of profiles across the globe, sulfidic models showing that the sulfidic water first occurred in the deep water during the early-middle Capitanian and shoaled to shallow water in the middle-late Capitanian could be established, despite the fact that the temporally and spatially heterogeneous sulfidic processes in the late Guadalupian are still debated.
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Heriot-Watt University
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