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
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Facies
Journal Prestige (SJR): 0.669
Citation Impact (citeScore): 2
Number of Followers: 10  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1612-4820 - ISSN (Online) 0172-9179
Published by Springer-Verlag Homepage  [2626 journals]
  • Endolithic and epilithic sponges of archaeological marble statues
           recovered in the Blue Grotto, Capri (Italy) and in the Antikythera
           shipwreck (Greece)
    • Abstract: Abstract Boring sponges are among the most important erosive organisms causing relevant damage on calcium carbonate substrates in marine environments. The present work offers a contribution to the knowledge of the bioerosive impact of sponges on archaeological artifacts such as the marble statues recovered from the shipwreck of Antikythera (Greece) and the Blue Grotto (Capri, Italy). These peculiar substrates lie on the seabed, but only little information is available about the risks during their underwater life. Bioeroding sponges caused the loss of substantial parts of the artifacts’ lithic substrate (penetrating up to some centimeters depth), often in association with microborers and boring bivalves. The results highlighted that the bioeroding species in Capri were mostly Dotona pulchella mediterranea, Cliona janitrix, Cliona schmidtii, and Spiroxya levispira. Their chambers were often filled by secondary, non-eroding sponges such as Agelas oroides, Jaspis incrustans, Dercitus (Stoeba) plicatus, Erylus sp., and Pachastrella monilifera. In the Antikythera statues, C. schmidtii was the most frequent species, often easily recognized by its purple color. It was often associated with other excavating sponges such as Cliona vermifera, and Dotona pulchella mediterranea. Pachastrella monilifera and Jaspis incrustans were also present as insinuating species. Incomplete sets of spicules and bioerosion pits observed by SEM were referred to the genera Alectona and Siphonodictyon. The presence of the sciophilous epilithic species Petrobiona massiliana and Merlia normani in both sites revealed that these archeological sites have comparable environmental conditions. The study allowed the identification of the sponges involved in the colonization of calcareous artifacts and the definition of the important role they played in the damage of the statues.
      PubDate: 2019-03-22
      DOI: 10.1007/s10347-019-0562-7
       
  • Larger foraminifera and strontium isotope stratigraphy of middle Campanian
           shallow-water lagoonal facies of the Pyrenean Basin (NE Spain)
    • Abstract: Abstract The Upper Cretaceous Terradets Limestone of the south Pyrenean Basin consists of two subunits, named the Lower Terradets and the Upper Terradets. In the Lower Terradets subunit, sedimentological features and fossil content permit distinguishing mid-ramp, bioclastic shoal and inner-ramp lagoonal facies associations, each characterized by a distinctive larger foraminiferal assemblage. Mid-ramp facies contain epibenthic, relatively small foraminifera like Cuneolina cylindrica, Dictyopsella cf. cuvillieri, Pseudocyclammina sphaeroidea, Nummofallotia cretacea, Fallotia' sp., Pararotalia cf. tuberculifera, Praestorrsella roestae and Praesiderolites praevidali. Bioclastic shoal facies are dominated by Orbitoides cf. tissoti, Praesiderolites douvillei, and Pseudosiderolites sp. The inner-ramp lagoonal facies contain a rich and diverse assemblage of epiphytes, like Ilerdorbis decussatus, Dicyclina schlumbergeri, and Cyclopsinella roselli n. sp., and epibenthic foraminifera, like Calveziconus lecalvezae and Orbitokathina campaniana. Strontium isotope stratigraphy indicates a middle Campanian age for the Lower Terradets limestone.
      PubDate: 2019-03-22
      DOI: 10.1007/s10347-019-0565-4
       
  • The role of polychaetes in bioerosion of submerged mosaic floors in the
           Underwater Archaeological Park of Baiae (Naples, Italy)
    • Abstract: Abstract The study investigated the role of boring polychaetes in the bioerosion of a submerged Roman mosaic floor in the Underwater Archaeological Park of Baiae (Naples, Italy). Three boring species, Dodecaceria concharum, Polydora ciliata, and Pseudopolydora antennata, were found. The initial colonization phases of boring polychaetes were investigated on experimental limestone panels placed underwater in the same marine area. The results showed that the ecological succession was characterized by a first stage of colonization with abundant spionids and a second stage with a boring mature community dominated by D. concharum. The study of silicone casts of the bored traces allowed confirmation that the ichnospecies belonging to the ichnogenera Maeandropolydora could be attributed to the action of spionid worms, whereas D. concharum is able to produce tongue- and ribbon-shaped borings (ichnogenus Caulostrepsis), and variously contorted galleries (ichnogenus Maeandropolydora) by settling inside borings produced by other polychaetes and increasing the complexity of the gallery system by modifying them. The study of the epilithic polychaete community highlighted that the site is characterized by a low hydrodynamism. Therefore, the most suitable in situ preservation interventions would be the covering of the mosaics with sand layers or geotextiles.
      PubDate: 2019-03-18
      DOI: 10.1007/s10347-019-0563-6
       
  • Study of the euendolithic activity of black meristematic fungi isolated
           from a marble statue in the Quirinale Palace’s Gardens in Rome, Italy
    • Abstract: Abstract The present study analyzed the dark patina present on the surface of a marble statue exposed in the Gardens of the Quirinal Palace in Rome, with a special focus on euendolithic black meristematic fungi. The study of the spatial distribution of microorganisms and their identification were performed by using a multistep approach based on microscopy, cultural analyses, molecular techniques, and embedding resin-casting technique. Black meristematic fungi were observed in the patina. Since morphological features are not sufficient to identify fungi belonging to this group, cultural and molecular analyses were performed. The results highlighted the presence of the species Coniosporium apollinis and of strains related to the genus Knufia (order of Chaetothyriales). The resin-casting embedding technique demonstrated the active penetration of these fungi into the marble grains, thus documenting their true endolithic behavior. The involvement of phototrophic microorganisms present on the surface in the active penetration of the marble was excluded.
      PubDate: 2019-03-15
      DOI: 10.1007/s10347-019-0564-5
       
  • Carbonate concretions in Miocene mudrocks in NW Algeria: types,
           geochemistry, and origins
    • Abstract: Abstract Carbonate concretions have been recorded in many recent and ancient marine sediments around the world. The Middle Miocene marl of the Tenes area, situated in the northeast of the Lower Chelif Basin in NW-Algeria, contains such carbonate concretions but with a variety of different structures and morphologies. Three different basic types are distinguished: nodular (spheroidal, ellipsoidal, disc, and irregular), stratiform, and tubular concretions, the last locally have a central conduit. The close association between carbonate concretions and synsedimentary deformation structures (synsedimentary faults, slumps) and normal faults, pronounced in the Ounsour Anhas outcrop, indicates synsedimentary instability related to upward fluid movement. The concretions were formed by precipitation of micritic carbonate within the host marl at shallow burial depth, probably in the active microbial methanogenesis zone. Strongly varying δ13C values (− 9.82 to + 5.85‰ PDB) are interpreted as the result of the balance between 13C-enriched (residual CO2 from methanogenesis) and 13C-depleted (microbial organic matter decomposition) CO2 added to the pore solutions. δ18O values (− 2.39 to + 1.71‰ PDB) indicate that carbonate concretion growth occurred during early diagenesis conditions, from marine-derived pore-water.
      PubDate: 2019-03-13
      DOI: 10.1007/s10347-019-0559-2
       
  • Simple methods for detection of microborings produced by coral-associated
           microendoliths
    • Abstract: Abstract Well-preserved skeletons of Paleocene and Eocene scleractinians and octocorals (Polytremacis sp.) from Poland and Ukraine were studied to reveal microborings produced in vivo by coral-associated microendoliths. Microborings (mostly < 5 μm in diameter) are hardly visible, if at all, under a petrographic microscope. Their resin casts are obtained, however, through the epoxy vacuum cast-embedding technique and observed under a scanning electron microscope (SEM). Three-dimensional resin-filled (cast) microborings are also clearly visible under SEM in acid-etched petrographic thin-sections. Backscattered scanning electron microscopy imaging (BSE) is useful for visualization of the microborings during SEM study of both etched and non-etched thin-sections. A simple but very effective method to reveal the dense network of resin casts of microborings is observations of etched thin-sections under the petrographic microscope. Fluorescence microscopy (FL), especially with application of blue and green filters (Nikon’s B-1A and G-2A filter cubes), is recommended if etching thin-sections or polished samples is not possible. However, color contrast between the resin casts and the calcium carbonate of the coral skeleton was strong enough only in some examined thin-sections. The cathodoluminescence microscopy, the other method, does not require the etching of the thin-sections and is potentially useful for detection of microborings filled with calcite cement, although this technique was not applicable for the samples studied. Symbiotic coral-microendolith association (in broad meaning of the term symbiosis) is a common phenomenon in modern corals, but its fossil record is very sparse. This study shows that empty microborings can be common in fossil corals, allowing preparation of the resin casts. Some of the tested methods permit rapid detection of resin-filled microborings in thin-sections even by non-specialists, and selection of samples for SEM studies. Corals from claystones and mudstones, usually less affected by diagenesis, have higher taphonomic potential for preservation of empty microborings than corals from reef facies. The methods discussed here can be also applied for rapid detection of post-mortem microborings occurring in other substrates.
      PubDate: 2019-03-12
      DOI: 10.1007/s10347-019-0560-9
       
  • Anatomy of the Book Canyon conglomerate: a sequence boundary at the top of
           the Bear Gulch Limestone in the Big Snowy Trough
    • Abstract: Abstract The Serpukhovian Book Canyon Conglomerate is an unpublished limestone conglomerate contained within the Tyler Formation in central Montana. It overlies and contains clasts of the Bear Gulch Limestone, a plattenkalk deposit yielding amazing paleontological detail. The Book Canyon Conglomerate is up to 2 m thick, markedly lensoid, and laterally discontinuous in its outcrop for a distance of 2 km but likely extends beyond the study area. Well logs and cores indicate its presence in the subsurface between the underlying Bear Gulch Limestone (Serpukhovian) and overlying Tyler Formation (Serpukhovian–Morrowan). This conglomerate provides new information regarding the transition of the marine-dominated Bear Gulch Limestone to the overlying Tyler Formation. The Book Canyon Conglomerate is dominantly clast-supported and includes sedimentary structures including pebble and cobble imbrication, tangential cross-stratification, and an overall upward-fining character. The basal surface of the conglomerate is sharp and irregular where the top of the underlying Bear Gulch Limestone has been erosionally removed. The Book Canyon Conglomerate is therefore interpreted as a fluvial channel deposit formed on a surface of subaerial exposure at the top of the Bear Gulch Limestone. In areas where the conglomerate is thin or absent, the top of the Bear Gulch Limestone is interpreted as a paleosol developed in a semi-arid climate where it is preserved between channel incisions of the Book Canyon Conglomerate. The paleosol contains microcrystalline silica cement and limestone clasts that have weathered to a black color. Freshwater exposure and channelized fluvial erosion early in the post-depositional history of the Bear Gulch Limestone explain variations in the contacts between units. These variations contribute to the debate concerning stratigraphic relationships. Further analysis of unconformities and fauna at the base and top of the unit clarifies the Bear Gulch Limestone’s position in time, and its relationship to the Heath and Tyler Formations.
      PubDate: 2019-02-24
      DOI: 10.1007/s10347-019-0557-4
       
  • Psammobiosis and bioerosion: examining ecological strategies in sponges
           using the case example Coelocarteria singaporensis
    • Abstract: Abstract The endolithic and endopsammic habits in sponges promote similar morphologies and offer similar ecological niches of being protected and anchored. We assessed whether this also induces similar functions, i.e., whether the commonly endopsammic sponge Coelocarteria singaporensis (Carter, 1883) shares bioerosion capabilities with clionaid endopsammic sponges such as some Spheciospongia species, enabling it to inhabit and also to expand within calcareous substrates. We studied a range of traits that are commonly accepted as evidence for bioerosion. C. singaporensis has a globular or irregular body from which fistules arise, but the fistules never penetrated calcareous substrate, and while endopsammic specimens were able to agglutinate and incorporate particles, their bodies were not embedded within calcareous rock. Tough tissue filled small cavities in adjacent rock, but only in a few exceptions did we find sponge chips in it. We encountered the only indication for possible active bioerosion in the form of sponge scars and canals in some of the substrate the sponge touched or had embedded, but these areas lacked fresh erosion fissures and well-defined erosion scars and may have been made by other species. If C. singaporensis is able to bioerode, it does not seem to cut out chips to produce a regular shagreen pattern. The sponge clearly has the ability to insinuate into pre-existing cavities, but overall we regard the evidence for its bioerosion capability as circumstantial or unreliable. At this stage, we can neither confirm nor reject that this sponge may be able to bioerode calcareous material, but it appears to be unlikely.
      PubDate: 2019-02-18
      DOI: 10.1007/s10347-019-0556-5
       
  • The lower Upper Cretaceous of the south-eastern Münsterland Cretaceous
           Basin, Germany: facies, integrated stratigraphy and inter-basinal
           correlation
    • Abstract: Abstract Integrated stratigraphic (litho-, bio-, event, chemo-, gamma ray, and sequence stratigraphy) and sedimentologic analyses of two new core sections greatly improved the understanding of facies development, sea-level changes and correlation of the lower Upper Cretaceous in the south-eastern Münsterland Cretaceous Basin, Germany. A large-scale second-order sea-level cycle is mirrored by the increasing importance of offshore facies and thicknesses of depositional sequences, reflecting the rise of accommodation during the Cenomanian to Early Turonian. In the Middle Turonian, this trend started to become reversed and the cycle ends with a major unconformity at the base of the Soest Grünsand Member in the mid-Upper Turonian. Condensation of the mid- and uppermost Turonian reflects the lack of accommodation during a phase of second-order lowstand, followed by a retrogradational trend during the Early Coniacian that marks the transgressive part of a new second-order cycle. Sedimentary unconformities in the Cenomanian–Turonian successions provide evidence for third-order sea-level changes superimposed onto the first early Late Cretaceous second-order cycle. They correspond to sequence boundaries SB Ce 1–5 and SB Tu 1–4 that have been identified in Central European basins and elsewhere, supporting their eustatic origin. The sea-level fall expressed by Upper Turonian unconformity SB Tu 4 is of major magnitude. The overlying Soest Grünsand Member is the only level of greensands in the Upper Turonian of the south-eastern Münsterland: the Alme Grünsand, introduced for another, allegedly uppermost Turonian greensand level, does not exist. Carbon stable isotopes from the mid-Upper Cenomanian to Lower Coniacian allowed calibrating the successions on intra- and interbasinal scales. A conspicuous mid-Middle Turonian positive isotope event has been newly named, i.e., the Niederntudorf Event. Sequence boundaries, marker beds (marl layers) and bentonites turned out to be isochronous within the chemostratigraphic framework. The identification of Turonian bentonites greatly improved the understanding of the stratigraphic relationships, especially in the Upper Turonian while natural gamma radiation logs turned out as a valuable method for intrabasinal correlation. In conclusion, the new sections provide a high-quality standard succession for the lower Upper Cretaceous in the south-eastern Münsterland Cretaceous Basin.
      PubDate: 2019-02-05
      DOI: 10.1007/s10347-018-0552-1
       
  • Challenging asymmetric cements as indicators of vadose diagenesis:
           “pseudo-gravitational” cements from the lower Pliensbachian of the
           Traras Mountains in NW Algeria
    • Abstract: Abstract Asymmetric, pendant cements are considered good indicators for early lithification in the vadose zone. In the present study, asymmetric cements are recorded in thin-sections of a Lower Jurassic limestone from the Traras Mountains (northwest Algeria). Geopetal fabrics, however, indicate that these seemingly “pendant cements” are, in some places, oriented upwards, i.e., they have grown in the opposite direction from that expected, or they grew from grains towards the pore centers. These observations disprove their origin as gravitational cements precipitated from pendant water droplets on the undersides of grains as in the vadose zone. In contrast, a formation in the marine phreatic zone seems more probable. Under high-energy conditions, and after an early lithification stage with isopachous cements in the subtidal zone, strong tidally driven horizontal pore-water flow allowed sufficient seawater to pass through the slightly cemented but still highly permeable rock. Those grain sides, which were oriented towards the pore center, where faster flowing water prevailed, were more exposed to CaCO3-supersaturated percolating seawater and therefore the cements precipitated here show their greatest thickness. In relatively more protected areas around the margins of the pores, asymmetric cements are rarely developed. The resulting rock exhibits an unusual, heterogeneous cementation with preferential centripetal nucleation areas.
      PubDate: 2019-02-04
      DOI: 10.1007/s10347-019-0554-7
       
  • Anthracoporella – Palaeoaplysina mound in Upper Carboniferous
           mid-Panthalassan atoll-type carbonates in a Jurassic accretionary complex,
           central Japan
    • Abstract: Abstract The Carboniferous–Permian Kano-yama limestone in the Jurassic Chichibu Accretionary Complex, central Japan, contains an algal-microbial mound composed of Anthracoporella, Palaeoaplysina, Tubiphytes, Archaeolithoporella, and bryozoans. The limestone is characterized by abundant micrite, implying a low-energy back-reef depositional environment. The fusuline fauna includes Daixina sokensis, Carbonoschwagerina minatoi and C. morikawai, which are representative of the Gzhelian Stage of the Carboniferous. Anthracoporella and Palaeoaplysina are interpreted to be the main bafflers in the mound. The lower horizon of the mound is characterized by a binding structure of Tubiphytes, Archaeolithoporella and bryozoans, which enabled the formation of this Anthracoporella and Palaeoaplysina mound. Compared with the Akiyoshi–Taishaku limestone, a well-documented Panthalassan atoll-type carbonate, the occurrence of Palaeoaplysina is a common feature of these limestones. Based on their accretion ages, the Kano-yama limestone is estimated to have been located several thousand kilometers west of the Akiyoshi–Taishaku limestone in the Panthalassa Ocean during the latest Carboniferous. The occurrence of Palaeoaplysina in both the Akiyoshi–Taishaku and Kano-yama limestones indicates that the distribution of Palaeoaplysina, which is known to be a cool-water genus, extended over thousands of kilometers in the Panthalassa during the period of the Gondwana glaciation.
      PubDate: 2019-02-01
      DOI: 10.1007/s10347-019-0555-6
       
  • Study of the bioerosion of Phoenician elephant tusks from the shipwreck of
           Bajo de la Campana: lots of hypotheses, few certainties
    • Abstract: Abstract The shipwreck of Bajo de la Campana (VII–VI century B.C.) was a Phoenician merchant ship accidentally discovered in the 1950s off the coasts of the Murcia region (Spain). Sixty-four elephant tusks were part of the cargo. Some of them were recovered by archaeologists between 2007 and 2011 and are now stored in the restoration laboratory of the National Museum of Underwater Archaeology (ARQVA) of Cartagena. This study investigated the bioerosion traces present on 12 selected tusks in order to hypothesize which marine or terrestrial macroborers could have attacked this substrate. No work has previously looked at the biological degradation of this material. Taking into account the mineral composition of ivory, the hypothesized bioeroders were selected from those reported in the literature as bioeroders of rocks or other hard substrates (bones, corals, shells, etc.). The hypothesized biodeteriogens belongs to several groups of marine invertebrates (echinoids, barnacles, molluscs, sponges, polychaetes, and bryozoans) and terrestrial insects. Unfortunately, the absence of parts of the bioeroders’ body or of skeletal elements inside the studied traces did not allow definitive identification, so the attributions remain hypotheses. However, this study could be considered a starting point for an interesting debate and for future investigations on the bioerosion of this precious material.
      PubDate: 2019-01-29
      DOI: 10.1007/s10347-019-0553-8
       
  • Eocene resedimented limestone deposits from the Osa Peninsula, Costa Rica:
           slope-apron accumulation in a volcanic forearc environment
    • Abstract: Abstract Eocene limestones from the Osa Peninsula of southern Costa Rica were deposited in a slope-apron environment in an active volcanic forearc setting. Larger foraminiferal assemblages from clasts and beds record two main resedimented carbonate microfacies: a dominant Eoconuloides–Helicostegina–Eulinderina facies from the middle Eocene (Lutetian) and a subordinate Lepidocyclina tobleri panamensis–Lepidocyclina (Nephrolepidina) chaperi facies from the upper Eocene (uppermost Bartonian–Priabonian). Both facies consist of abundant shallow-marine benthic carbonate, volcaniclastic, and planktic materials that were re-deposited by gravity flows into a deeper-marine forearc basin. The accessory volcaniclastic grain assemblages are bimodal in composition, comprising differentiated rock and ejecta fragments derived from explosive arc volcanism in addition to basaltic grain contributions from the volcanic forearc basement. The source of the carbonate materials was likely the Fila de Cal carbonate platform presently located in the adjoining arc-ward region of the Fila Costeña thrust belt. Strong biostratigraphic correlations with platform carbonate and other similar forearc successions bearing resedimented limestones reveal not only a provenance from carbonate environments within the arc but they also record coeval events of resedimentation along a continuous deep-marine forearc slope. The sedimentary sequence was deformed as result of coeval basaltic activity and fault tectonics. There is no evidence of accumulation by accretionary processes in the carbonate deposits studied. The findings indicate that the basement of the Osa Peninsula and its sedimentary cover probably formed part of the Costa Rican forearc that was uplifted and deformed in response to basaltic volcanic activity and subsequent Cocos Ridge subduction.
      PubDate: 2019-01-11
      DOI: 10.1007/s10347-018-0549-9
       
  • Carbonate dissolution by reef microbial borers: a biogeological process
           producing alkalinity under different pCO 2 conditions
    • Abstract: Abstract Rising atmospheric CO2 is acidifying the world’s oceans, affecting both calcification and dissolution processes in coral reefs. Among processes, carbonate dissolution by bioeroding microflora has been overlooked, and especially its impact on seawater alkalinity. To date, this biogeological process has only been studied using microscopy or buoyant weight techniques. To better understand its possible effect on seawater alkalinity, and thus on reef carbonate budget, an experiment was conducted under various seawater chemistry conditions (2 ≤ Ωarag ≤ 3.5 corresponding to 440 ≤ pCO2 (µatm) ≤ 940) at 25 °C under night and daylight (200 µmol photons m−2 s−1) with natural microboring communities colonizing dead coral blocks (New Caledonia). Both the alkalinity anomaly technique and microscopy methods were used to study the activity of those communities dominated by the chlorophyte Ostreobium sp. Results show that (1) the amount of alkalinity released in seawater by such communities is significant and varies between 12.8 ± 0.7 at ΩArag ~ 2 and 5.6 ± 0.4 mmol CaCO3 m−2 day−1 at ΩArag ~ 3–3.5 considering a 12:12 photoperiod; (2) although dissolution is higher at night (~ 80 vs. 20% during daylight), the process can occur under significant photosynthetic activity; and (3) the process is greatly stimulated when an acidity threshold is reached (pCO2 ≥ 920 µatm vs. current conditions at constant light intensity). We show that carbonate dissolution by microborers is a major biogeochemical process that could dissolve a large part of the carbonates deposited by calcifying organisms under ocean acidification.
      PubDate: 2019-01-11
      DOI: 10.1007/s10347-018-0548-x
       
  • Bioerosion in fossil cephalopods: a case study from the Upper
           Carboniferous Buckhorn Asphalt Quarry Lagerstätte, Oklahoma, USA
    • Abstract: Abstract The mid-Pennsylvanian (Desmoinesian–Virgilian) deposits from the Buckhorn Asphalt Quarry Lagerstätte near Sulphur, Oklahoma, are characterized by siliciclastic–carbonate rocks. One of these deposits is the ‘cephalopod coquina’ that contains a large amount of orthocerid and coiled nautiloid, and ammonoid shell remains. These were used for a detailed study on bioerosion in cephalopod shells in order to help in the reconstruction of the paleoenvironment and to increase the general knowledge on bioerosion in fossil cephalopods. More than 50 shell fragments were cast and investigated. The shells cast and investigated in this study comprise a diverse set of ichnotaxa-/forms. Besides chlorophyte and cyanobacterial traces, also rhodophyte, fungal, and spongal traces are present as well as those of unknown origin. In addition, there are six ichnoforms that might have foraminiferans as producers. In orthoceratids, Ichnoreticulina elegans and a curly morphotype of Scolecia isp. are most common while the abundance in coiled cephalopods is dominated by the ‘superthin form’, the ‘extremely thin form’, and Flagrichnus profundus. In total, 22 ichnotaxa and -forms were recognized and 12 of these have their oldest record in the Carboniferous. The succession of ichnotaxa/-forms in the casts of orthocones suggests deposition in the deep euphotic to dysphotic zone of the Buckhorn sea while shells of coiled specimens had drifted for a while; they were therefore more prone to bioerosion by autotrophs until they sank to the seafloor.
      PubDate: 2019-01-10
      DOI: 10.1007/s10347-018-0547-y
       
  • Paleoenvironment and taphonomy of lower Miocene bivalve and macroid
           assemblages: the Lagos Biocalcarenite (Lagos-Portimão Formation, southern
           Portugal)
    • Abstract: Abstract Between Lagos and Albufeira, the Algarve coast of southern Portugal is marked by outcrops of the lower Miocene Lagos-Portimão Formation (LPF) consisting of yellow sandstone and coarse skeletal-rhodolithic limestone. This contribution focuses on the rhodoliths, their paleoecology, taphonomy, and biological composition, in the Lagos Biocalcarenite, the lower member of the LPF. Special attention is paid to the unusual occurrence of numerous rhodoliths nucleated around articulated bivalve shells, as well as to the nature of their biological interactions and taphonomic features. The calcareous algae of the rhodoliths (Phymatolithon calcareum and Spongites sp.) are commonly interlayered with thin bands of bryozoans and serpulids. Thick beds of non-nucleated spheroidal rhodoliths first appear at approximately 5–6 m above the base of the LPF as a result of a storm event that shifted rhodoliths in a shoreward direction. The bioeroded surface at the top of the Cretaceous Porto de Mós Formation, at the base of the overlying LPF succession, is a wave-cut platform representing the Miocene transgressive surface.
      PubDate: 2019-01-10
      DOI: 10.1007/s10347-018-0550-3
       
  • Bioerosion structures in a Late Cretaceous mosasaur from Antarctica
    • Abstract: Abstract Bioerosive structures in the cortical region of a vertebra from a mosasaur fall in the López de Bertodano Formation (Upper Maastrichtian) in Seymour Island (Isla Marambio), Antarctica, are reported. The traces studied are similar but not coincident with the described microborings in other fossil bone remains. The morphology and extension of these bioerosive structures are considered as the result of the activity of endolithic organisms on the original vascular channels of the bone. They are approximately straight, anastomosed, and commonly filled with an opaque mineral and framboidal pyrite. As most of the bone structure is well preserved, only the small portion of the cortical region was exposed to the microorganisms’ activity. This would mean that the mosasaur individual died well earlier than the burial event. This is their first report of this type of bioerosive structures in a mosasaur fall.
      PubDate: 2019-01-05
      DOI: 10.1007/s10347-018-0551-2
       
  • Middle Miocene carbonate facies with rhodoliths from the NW Transylvanian
           Basin (Vălenii Șomcutei Cave, Romania)
    • Abstract: Abstract The middle Miocene carbonates from the NW part of the Transylvanian Basin are represented mainly by rhodalgal facies. This paper provides an accurate taxonomic account of the red algal assemblages, facies analysis, and paleoenvironmental interpretation of the Badenian deposits outcropping in Vălenii Șomcutei area. A total of 13 red algal species belonging to the orders Corallinales, Hapalidiales, Sporolithales, and Peyssonneliales have been identified. The microfacies distinguished in the succession (bio-extraclastic grainstone, oolitic packstone/grainstone, bio-extraclastic packstone/grainstone, rhodolith rudstone, coralline algal rudstone, and coralline algal debris grainstone) suggest a general shallowing-upward succession, from an open-marine middle-outer ramp setting to an inner-ramp environment.
      PubDate: 2019-01-03
      DOI: 10.1007/s10347-018-0546-z
       
  • Spatial and temporal facies evolution of a Lower Jurassic carbonate
           platform, NW Tethyan margin (Mallorca, Spain)
    • Abstract: Abstract The variety of depositional facies of a Lower Jurassic carbonate platform has been investigated on the island of Mallorca along a transect comprising six stratigraphic profiles. Twenty-nine facies and sub-facies have been recognized, grouped into seven facies associations, ranging in depositional environment from supratidal/terrestrial and peritidal to outer platform. Spatial and temporal (2D) facies distribution along the transect reflects the evolution of the carbonate platform with time showing different facies associations, from a broad peritidal platform (stage 1) to a muddy open platform (stage 2), and finally to a peritidal to outer carbonate platform (stage 3). Stage 1 (early Sinemurian to earliest late Sinemurian) corresponds to a nearly-flat peritidal-shallow subtidal epicontinental platform with facies belts that shifted far and fast over the whole study area. The evolution from stage 1 to stage 2 (late Sinemurian) represents a rapid flooding of the epicontinental shallow platform, with more open-marine conditions, and the onset of differential subsidence. During stage 3 (latest Sinemurian), peritidal and shallow-platform environments preferentially developed to the northeast (Llevant Mountains domain) with a rapid transition to middle-outer platform environments toward the northwest (Tramuntana Range domain). Stages 1 and 3 present facies associations typical of Bahamian-type carbonates, whereas stage 2 represents the demise of the Bahamian-type carbonate factory and proliferation of muddy substrates with suspension-feeders. The described platform evolution responded to the interplay between the initial extensional tectonic phases related to Early Jurassic Tethyan rifting, contemporaneous environmental perturbations, and progressive platform flooding related to the Late Triassic–Early Jurassic worldwide marine transgression and associated accommodation changes.
      PubDate: 2018-12-19
      DOI: 10.1007/s10347-018-0545-0
       
  • Hydrocarbon habitat in the Zielin Late Permian isolated carbonate
           platform, western Poland
    • Abstract: Abstract In the Zielin oilfield in the Polish part of the Southern Permian Basin, oil and gas are produced from an Upper Permian Main Dolomite (Ca2) isolated platform. The paleohigh developed on a volcanic cone formed in Early Rotliegend time. Based on microfacies analysis of Ca2 reservoir rocks from four wells (Zielin-1, -2, -3 and -3KBis), four microfacies types are distinguished: peloidal dolomitized wackestone, intraclastic dolomitized rudstone and floatstone, biogenic boundstone, and intraclastic-bioclastic dolomitized packstone. In view of the lack of source rocks on the Zielin paleohigh revealed by Rock–Eval analyses, this isolated carbonate platform is regarded as a reservoir for migrating hydrocarbons. Biomarker analyses of two crude oils and nine carbonate rocks from the Zielin isolated carbonate platform and five crude oils from surrounding wells of the nearest Gorzów, Cychry, and Namyślin platforms indicate an origin for the oils from oil–prone type II kerogen, sourced from organic matter deposited under anoxic/suboxic conditions in a carbonate environment. Compared to organic matter extracted from the rock samples, oils from the Zielin-2 and 3KBis wells are characterized by higher values of the pristane/phytane (Pr/Ph) and dibenzothiophene/phenanthrene (DBT/P) ratios, lower relative concentrations of polyalkylaromatics, as well as a higher maturity evaluated from the methylphenanthrene (MPI-1) and methyldibenzothiophene (MDR) indices. The molecular composition of sesquiterpanes, n-alkylbenzenes, and polyalkylnaphthalenes revealed a diverse specificity within the oils analyzed and allowed their separation into two groups. Oils Różańsko-4, Zielin-2, Zielin-3KBis, and Namyślin-1 represent group I, whereas Barnówko-3, Mostno-2 and Cychry-2 group II. From the gradient direction in the n-decane/naphthalene ratio and maturity for respective crude oils belonging to group I, it is concluded that the oils accumulated in the Zielin atoll migrated from NW to SE following subsidence and tilting of the platform in this part of the Main Dolomite basin.
      PubDate: 2018-12-10
      DOI: 10.1007/s10347-018-0544-1
       
 
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