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  Subjects -> GEOGRAPHY (Total: 493 journals)
Showing 1 - 200 of 277 Journals sorted by number of followers
Geophysical Research Letters     Full-text available via subscription   (Followers: 179)
Journal of Geophysical Research : Space Physics     Full-text available via subscription   (Followers: 157)
Journal of Geophysical Research : Atmospheres     Partially Free   (Followers: 144)
Journal of Geophysical Research : Planets     Full-text available via subscription   (Followers: 136)
Remote Sensing of Environment     Hybrid Journal   (Followers: 96)
Antipode     Hybrid Journal   (Followers: 65)
Journal of Geophysical Research : Earth Surface     Partially Free   (Followers: 60)
Journal of Geophysical Research : Oceans     Partially Free   (Followers: 60)
Progress in Human Geography     Hybrid Journal   (Followers: 59)
Journal of Geophysical Research : Solid Earth     Full-text available via subscription   (Followers: 58)
International Journal of Geographical Information Science     Hybrid Journal   (Followers: 55)
GIScience & Remote Sensing     Open Access   (Followers: 54)
Journal of Water and Climate Change     Open Access   (Followers: 53)
Climate Change Economics     Hybrid Journal   (Followers: 50)
Reviews of Geophysics     Full-text available via subscription   (Followers: 49)
Remote Sensing Letters     Hybrid Journal   (Followers: 46)
Annals of the American Association of Geographers     Hybrid Journal   (Followers: 43)
Economic Geography     Hybrid Journal   (Followers: 40)
Applied Geography     Hybrid Journal   (Followers: 38)
Geochemistry, Geophysics, Geosystems     Full-text available via subscription   (Followers: 35)
Urban Geography     Hybrid Journal   (Followers: 34)
Journal of Geophysical Research : Biogeosciences     Full-text available via subscription   (Followers: 34)
Climate and Development     Hybrid Journal   (Followers: 33)
Journal of Coastal Research     Hybrid Journal   (Followers: 31)
Annals of GIS     Open Access   (Followers: 31)
Cartography and Geographic Information Science     Hybrid Journal   (Followers: 31)
GPS Solutions     Hybrid Journal   (Followers: 28)
Transactions of the Institute of British Geographers     Hybrid Journal   (Followers: 27)
Journal of Urbanism: International Research on Placemaking and Urban Sustainability     Hybrid Journal   (Followers: 24)
Journal of the Middle East and Africa     Hybrid Journal   (Followers: 22)
China : An International Journal     Full-text available via subscription   (Followers: 20)
Urban Research & Practice     Hybrid Journal   (Followers: 20)
Dialogues in Human Geography     Hybrid Journal   (Followers: 20)
Imago Mundi: The International Journal for the History of Cartography     Hybrid Journal   (Followers: 20)
Atmospheric Measurement Techniques (AMT)     Open Access   (Followers: 19)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 19)
Water International     Hybrid Journal   (Followers: 19)
Journal of the American Planning Association     Hybrid Journal   (Followers: 19)
Journal of Cultural Geography     Hybrid Journal   (Followers: 18)
Geography Compass     Hybrid Journal   (Followers: 18)
Professional Geographer     Hybrid Journal   (Followers: 17)
Cartographica : The International Journal for Geographic Information and Geovisualization     Full-text available via subscription   (Followers: 17)
Africa Insight     Full-text available via subscription   (Followers: 16)
The Geographical Journal     Hybrid Journal   (Followers: 16)
International Geology Review     Hybrid Journal   (Followers: 16)
Crossings : Journal of Migration & Culture     Hybrid Journal   (Followers: 16)
Computational Geosciences     Hybrid Journal   (Followers: 16)
Tectonics     Full-text available via subscription   (Followers: 15)
American Journal of Geographic Information System     Open Access   (Followers: 14)
Geographical Review     Hybrid Journal   (Followers: 13)
Buildings & Landscapes: Journal of the Vernacular Architecture Forum     Full-text available via subscription   (Followers: 13)
Geomatics, Natural Hazards and Risk     Open Access   (Followers: 13)
International Indigenous Policy Journal     Open Access   (Followers: 13)
Annual Review of Marine Science     Full-text available via subscription   (Followers: 13)
Progress in Physical Geography     Hybrid Journal   (Followers: 13)
Bulletin of Geosciences     Open Access   (Followers: 12)
American Journal of Human Ecology     Open Access   (Followers: 11)
Geographical Research     Hybrid Journal   (Followers: 11)
Geographical Analysis     Hybrid Journal   (Followers: 11)
Canadian Journal of Soil Science     Full-text available via subscription   (Followers: 11)
Geosciences Journal     Hybrid Journal   (Followers: 10)
GeoJournal     Hybrid Journal   (Followers: 10)
Journal of Geography     Hybrid Journal   (Followers: 10)
European Spatial Research and Policy     Open Access   (Followers: 9)
Cartographic Journal     Hybrid Journal   (Followers: 9)
Atmospheric Measurement Techniques Discussions (AMTD)     Open Access   (Followers: 9)
Journal of Borderlands Studies     Hybrid Journal   (Followers: 8)
Geography and Natural Resources     Hybrid Journal   (Followers: 8)
Physical Geography     Hybrid Journal   (Followers: 8)
Natural Science     Open Access   (Followers: 8)
Journal of Iberian and Latin American Research     Hybrid Journal   (Followers: 8)
Middle East Development Journal     Hybrid Journal   (Followers: 8)
Geo-spatial Information Science     Open Access   (Followers: 7)
Nordic Journal of Migration Research     Open Access   (Followers: 7)
Social Geography Discussions (SGD)     Open Access   (Followers: 7)
International Journal of Applied Geospatial Research     Hybrid Journal   (Followers: 7)
California Italian Studies Journal     Full-text available via subscription   (Followers: 7)
Journal of Latin American Geography     Full-text available via subscription   (Followers: 7)
Urban History Review / Revue d'histoire urbaine     Full-text available via subscription   (Followers: 7)
GeoInformatica     Hybrid Journal   (Followers: 7)
International Journal of Health Geographics     Open Access   (Followers: 7)
Northern Scotland     Hybrid Journal   (Followers: 6)
Journal of Geographical Systems     Hybrid Journal   (Followers: 6)
Asia Policy     Full-text available via subscription   (Followers: 6)
Singapore Journal of Tropical Geography     Hybrid Journal   (Followers: 6)
Australian Geographer     Hybrid Journal   (Followers: 6)
Ocean Science Journal     Hybrid Journal   (Followers: 6)
Journal of Maps     Open Access   (Followers: 6)
The Canadian Geographer/le Geographe Canadien     Hybrid Journal   (Followers: 6)
Journal of Map & Geography Libraries     Hybrid Journal   (Followers: 5)
ISPRS International Journal of Geo-Information     Open Access   (Followers: 5)
Journal of Developmental Entrepreneurship     Hybrid Journal   (Followers: 5)
Current Research in Geoscience     Open Access   (Followers: 5)
Creativity Studies     Open Access   (Followers: 5)
Australian Antarctic Magazine     Free   (Followers: 5)
Focus on Geography     Partially Free   (Followers: 5)
Asian Geographer     Hybrid Journal   (Followers: 5)
Journal of Australian Studies     Hybrid Journal   (Followers: 5)
Bulletin of the Ecological Society of America     Open Access   (Followers: 4)
Geografiska Annaler, Series A : Physical Geography     Hybrid Journal   (Followers: 4)
Journal of Sedimentary Research     Hybrid Journal   (Followers: 4)
Genre & histoire     Open Access   (Followers: 4)
Globe, The     Full-text available via subscription   (Followers: 4)
Latinoamérica. Revista de estudios Latinoamericanos     Open Access   (Followers: 4)
Applied Geomatics     Hybrid Journal   (Followers: 4)
Transmodernity : Journal of Peripheral Cultural Production of the Luso-Hispanic World     Open Access   (Followers: 4)
Interaction     Full-text available via subscription   (Followers: 3)
Journal of Western Archives     Open Access   (Followers: 3)
Limnological Review     Open Access   (Followers: 3)
Lithosphere     Open Access   (Followers: 3)
Bulletin of Geography. Socio-economic Series     Open Access   (Followers: 3)
Southeastern Europe     Hybrid Journal   (Followers: 3)
New Zealand Journal of Geography     Hybrid Journal   (Followers: 3)
International Journal of Image and Data Fusion     Hybrid Journal   (Followers: 3)
Économie rurale     Open Access   (Followers: 3)
Polar Research     Open Access   (Followers: 3)
South Asian Diaspora     Hybrid Journal   (Followers: 3)
Journal of Burma Studies     Full-text available via subscription   (Followers: 3)
Social Dynamics: A journal of African studies     Hybrid Journal   (Followers: 3)
All Earth     Open Access   (Followers: 3)
Pastoralism : Research, Policy and Practice     Open Access   (Followers: 2)
Maine Policy Review     Open Access   (Followers: 2)
The South Asianist     Open Access   (Followers: 2)
Provincial China     Hybrid Journal   (Followers: 2)
Geodesy and Cartography     Open Access   (Followers: 2)
Polar Journal     Hybrid Journal   (Followers: 2)
Regional Science Policy & Practice     Hybrid Journal   (Followers: 2)
History of Geo- and Space Sciences     Open Access   (Followers: 2)
Mineralogia     Open Access   (Followers: 2)
Eastern European Countryside     Open Access   (Followers: 2)
Regions and Cohesion     Open Access   (Followers: 2)
Geosphere     Open Access   (Followers: 2)
Journal of Earthquake and Tsunami     Hybrid Journal   (Followers: 2)
Cahiers franco-canadiens de l'Ouest     Full-text available via subscription   (Followers: 2)
Norois     Open Access   (Followers: 2)
Standort - Zeitschrift für angewandte Geographie     Hybrid Journal   (Followers: 2)
Études rurales     Open Access   (Followers: 2)
Polar Geography     Hybrid Journal   (Followers: 2)
Scottish Geographical Journal     Hybrid Journal   (Followers: 2)
Norsk Geografisk Tidsskrift - Norwegian Journal of Geography     Hybrid Journal   (Followers: 2)
Southeastern Geographer     Full-text available via subscription   (Followers: 2)
Yearbook of the Association of Pacific Coast Geographers     Full-text available via subscription   (Followers: 2)
BioRisk     Open Access   (Followers: 2)
Geographical Education     Full-text available via subscription   (Followers: 2)
Cahiers Balkaniques     Open Access   (Followers: 2)
Reflets : revue d'intervention sociale et communautaire     Full-text available via subscription   (Followers: 2)
Études internationales     Full-text available via subscription   (Followers: 1)
GEM - International Journal on Geomathematics     Hybrid Journal   (Followers: 1)
Recherches sociographiques     Full-text available via subscription   (Followers: 1)
Estudios Geográficos     Open Access   (Followers: 1)
Terrae Incognitae     Hybrid Journal   (Followers: 1)
Geoforum Perspektiv     Open Access   (Followers: 1)
Newfoundland and Labrador Studies     Full-text available via subscription   (Followers: 1)
South African Geographical Journal     Hybrid Journal   (Followers: 1)
Geochronometria     Open Access   (Followers: 1)
Amerika     Open Access   (Followers: 1)
Journal de la Société des Océanistes     Open Access   (Followers: 1)
Les Cahiers d'Outre-Mer     Open Access   (Followers: 1)
Revue archéologique du Centre de la France     Open Access   (Followers: 1)
Journal of Terrestrial Observation     Open Access   (Followers: 1)
PRISM : A Journal of Regional Engagement     Open Access   (Followers: 1)
Physio-Géo     Open Access   (Followers: 1)
Méditerranée     Open Access   (Followers: 1)
Indiana     Open Access   (Followers: 1)
Revista de Geografía Norte Grande     Open Access   (Followers: 1)
L'Année du Maghreb     Open Access   (Followers: 1)
European Countryside     Open Access   (Followers: 1)
Norteamérica     Open Access   (Followers: 1)
International Journal of Bahamian Studies     Open Access   (Followers: 1)
Journal of the Southwest     Full-text available via subscription   (Followers: 1)
PSC Discussion Papers Series     Open Access  
Anales de Geografía de la Universidad Complutense     Open Access  
International Journal of River Basin Management     Hybrid Journal  
Revista Geográfica de América Central     Open Access  
Multiciencias     Open Access  
Investigaciones Geográficas (Esp)     Open Access  
Sociedade & Natureza     Open Access  
Región y Sociedad     Open Access  
Migración y Desarrollo     Open Access  
Migraciones Internacionales     Open Access  
Investigaciones Geográficas     Open Access  
Frontera Norte     Open Access  
Cuadernos de Desarrollo Rural     Open Access  
Territoire en Mouvement     Open Access  
Quaestiones Geographicae     Open Access  
Limes. Cultural Regionalistics     Open Access  
GEOMATICA     Hybrid Journal  
Preview     Hybrid Journal  
Cuadernos de Geografía : Revista Colombiana de Geografía     Open Access  
Studia Universitatis Babes-Bolyai, Geologia     Open Access  
Recherches amérindiennes au Québec     Full-text available via subscription  
Rabaska : revue d'ethnologie de l'Amérique française     Full-text available via subscription  
Port Acadie : revue interdisciplinaire en études acadiennes / Port Acadie: An Interdisciplinary Review in Acadian Studies     Full-text available via subscription  
Études/Inuit/Studies     Full-text available via subscription  
Aurora Journal     Full-text available via subscription  
Revista de la Asociacion Geologica Argentina     Open Access  
San Francisco Estuary and Watershed Science     Open Access  
Journal of Alpine Research : Revue de géographie alpine     Open Access  
Géocarrefour     Open Access  
Confins     Open Access  

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Geosciences Journal
Journal Prestige (SJR): 0.381
Citation Impact (citeScore): 1
Number of Followers: 10  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1598-7477 - ISSN (Online) 1226-4806
Published by Springer-Verlag Homepage  [2469 journals]
  • Geochronology, geochemistry, Hf isotope, and electron probe analysis of
           the diorite in the Jianhei Mountain, East Kunlun Orogenic Belt, China, and
           their geological significance

    • Free pre-print version: Loading...

      Abstract: Abstract The Eastern Kunlun orogenic belt (EKOB) is located in southern margin of the Qaidam Basin. After the evolution of the Proto-Tethys Ocean and the Paleo-Tethys Ocean, the geological structure is complex and diverse in the EKOB. Herein, the results of geochronological, geochemical, Hf isotope, and electron probe analyses are presented for the Jianhei Mountain diorite in the EKOB. The results of the geochemical studies show that the rock is enriched in Al, Ca, and Fe, depleted in Ni and Cr, and contains moderate amounts of Mg. The samples exhibit a high degree of fractionation of light and heavy rare earth elements (REEs), with the light REEs being enriched, and the heavy REEs being depleted. Furthermore, the samples are enriched in the large ion lithophile elements, and depleted in the high field strength elements. The Jianhei Mountain diorite yields a weighted mean zircon U-Pb dating age of 251.3 ±1.8 Ma, which is in the Early Triassic. The Zircon Hf isotope analysis gives a zircon (Eu/Eu⋆)N value that ranges from −5.2 to −3.3, and the two-stage model age is 1244–1342 Ma. Combined with other geochemical characteristics, it can be concluded that the source area of the Jianhei Mountain diorite is dominated by Mesoproterozoic crustal materials, with a small amount of mantle material involved in the petrogenetic process. In addition, the results of electron probe micro-analysis show that the MgO content of the hornblende is 9.57–10.40%, the Mg/(Mg + Fe2+) ratio is 0.49–0.52, the Mg content is 2.15–2.31, the Ca content is 1.71–1.80, and the total of Fe3+ + Fe2+ is 2.04–2.17. The MgO content of the biotite is 8.47–9.31%, and the Fe2+/(Mg + Fe2+) ratio is 0.50–0.52. In accordance with previous studies, the mineral compositions of the hornblende and biotite are closely related to their genesis. It can be concluded that the hornblende and biotite of the Jianhei Mountain diorite have the characteristics of a crust-mantle mixed source. Overall, the present authors believe that the Jianhei Mountain diorite is the product of partial melting of the lower crust in the tectonic background of the northward subduction of the Paleo-Tethys Ocean, with a small amount of mantle material involved in the petrogenetic process.
      PubDate: 2022-08-01
       
  • Surface sediment geochemistry for understanding the recent sedimentary
           environment in northwestern Karnataka, south India

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      Abstract: Abstract Geochemical study of 195 stream sediment samples (in less than 75 µm grain size) distributed in parts of Belgaum, Dharwad, and Uttar Kanada districts (bounded by latitudes from 15°15′00″ to 15°30′00″ and longitudes from 74°30′00″ to 74°45′00″) were studied for the major oxide, trace and rare earth element content. The objective of this study is to understand the recent sedimentary environment by establishing the generalized climatic conditions, chemical weathering, sediment sorting and recycling, sediment sources, and the tectonic setting of the study area. Geochemical signatures of the sediments indicate a semi-arid to the moist climate in the study area. Geochemical proxies show that annual rainfall in the study area varies from 378 to 692 mm, higher in the western part compared to that in the eastern side. The chemical index of alteration (67.70–94.01) and chemical index of weathering (76.24–97.37) collectively suggest moderate to high chemical weathering. Studied samples show a wide variation in major oxides and trace elements. Fe2O3, MnO, K2O, P2O5, Rb, Zr, and Sc display a positive correlation with Al2O3 confirming their possible hydraulic fractionation. Zr/Sc vs. Th/Sc plot and correlation between CIA vs. Al2O3 indicate strong sediment recycling and sorting. Bulk geochemistry data suggests the involvement of granite and other felsic rocks, intermediate and mafic rocks as the sources of surface sediments. Our observations are very well matching with the geology of the area. Major and trace element set of discrimination diagrams demarcates the passive margin settings for the studied samples, except for a few samples plotting into an active continental margin tectonic settings.
      PubDate: 2022-08-01
       
  • Geochemistry and zircon U-Pb-Hf isotopes of igneous rocks associated with
           the Dongnam Fe-Mo skarn deposit, Taebaeksan Basin, South Korea

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      Abstract: Abstract The Dongnam Fe-Mo skarn deposit is located at the northern part of the Taebaeksan Basin, an important mineralized province in South Korea. The age of Fe-Mo mineralization is Late Cretaceous (79.1–75.9 Ma), and the orebodies are distributed along the contact between age-unknown igneous complex (quartz monzodiorite, granodiorite, and granite) and Pungchon Formation (limestone). Previous study suggested that the Dongnam Fe-Mo skarn deposit was mainly formed by the hydrothermal replacement of quartz monzodiorite. However, Fe-Mo mineralization and skarn are also commonly observed along the contact between granite and limestone, and the hydrothermal replacement of quartz monzodiorite began at the contact with granite. In this study, we conducted whole-rock geochemistry and zircon U-Pb-Hf isotope analyses to examine the characteristics of the ore-associated igneous rocks from the Dongnam deposit. Whole-rock chemistry and zircon Hf isotopes indicate that the granite was formed from crust-derived magma in a volcanic arc setting and exhibits geochemical characteristics (highly fractionated, oxidized, peraluminous, and high-K calc-alkaline etc.) similar to those from the Shinyemi and Wondong magnetite-associated igneous rocks in the Taebaeksan Basin. According to the zircon U-Pb age dating, quartz monzodiorite and granodiorite were emplaced in the Early Cretaceous (113.7–109.4 Ma) and granite was emplaced in the Late Cretaceous (80.3 Ma). Combined with geological observations, the geochemical and zircon U-Pb-Hf isotope data of the igneous rocks suggest that the Dongnam skarn Fe-Mo deposit was formed in association with Late Cretaceous granite derived from highly fractionated and oxidized magma, which is consistent with the mineralization age estimated by previous K-Ar and Re-Os dating.
      PubDate: 2022-08-01
       
  • Formation of talc fault gouge analog using high-energy ball mill

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      Abstract: Abstract Fault gouge, located in highly deformed fault cores, shows substantial particle size reduction and loss of crystallinity, which could affect the physicochemical properties and thus control the slip behavior and earthquake stability of a fault. To systematically investigate the effect of deformed fault gouge on fault slip behavior in laboratory-scale experiments, a fault gouge analog with variable particle size and crystallinity is required. However, the systematic study for formation of a fault gouge analog (i.e., controlling the particle size and crystallinity) was not performed well. In this study, we investigated the effect of the rotation speed of a high-energy ball mill on particle size reduction rate and degree of amorphization. As the rotation speed increased from 500 to 2000 rpm, the comminution rate linearly increased, and reached a reduced particle size limit. The degree of amorphization and its rate also increased with increasing rotation speed. Upon grinding, the X-ray diffraction (XRD) peaks markedly decreased and reached critical amorphization points within 120 min, except for the case of grinding with a rotation speed of 500 rpm. Talc ground with a rotation speed of 500 rpm did not reach steady-state in mechanical amorphization after 360 min of grinding, thus necessitating prolonged grinding for further amorphization. A comparison of talc powders having similar specific surface areas, but ground at different rotation speeds, shows that grinding with a higher rotation speed for a shorter duration preserves the crystalline structure relatively well compared with grinding at a lower rotation speed for a longer duration. These results indicate that optimizing the grinding rotation speed facilitates the formation of talc fault gouge analogs with systematically varying particle size and crystallinity. The specific surface area of talc increased from 6.1 to 365 m2/g, and the degree of crystallinity decreased from approximately 75% to 11%. Our results indicate that an artificial talc fault gouge can be prepared by varying the particle size and crystallinity using a high-energy ball mill.
      PubDate: 2022-08-01
       
  • Geoarchaeological observation of earlier palaeolithic (EP) assemblages of
           the downstream South Han River Area (SHRA), Korea

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      Abstract: Abstract This article introduces palaeolithic assemblages from the South Han River Area (SHRA) of South Korea and examines their ages in the geoarchaeological context. This task will be a starting point to discuss major factors responsible for the relatively late predominance of seemingly simple-and-crude Mode 1 toolkits in East Asia. Eight palaeolithic sites of the SHRA are covered and formation processes of their assemblages are examined based on geological features and published chronometric dates as well as additional proxy data. The ages of SHRA assemblages are roughly Late Pleistocene from MIS 5c to MIS 2. The lithic type variability of the SHRA is of typical Mode 1 technology which is principally composed of pebble-tools and minimally modified flakes. The issue of such a simple technology flourished in a limited area of East Asia during a quite late temporal range is discussed. A hypothetical explanation is that stone tools in the SHRA served as complementary items for making perishable primary living items out of organic materials and that local hominins were not obliged to be sedulous on such subsidiary items as stone tools. As a result, the nature of the SHRA assemblage looks apparently unlabored and expedient; this nature of lithic technology tends to be timeless and even survive anywhere anytime in East Asia, which can be recognized as retarded and not advanced.
      PubDate: 2022-08-01
       
  • Enhanced hypocenter determination of the 2017 Pohang earthquake sequence,
           South Korea, using a 3-D velocity model

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      Abstract: Abstract As a fundamental task in observational seismology, accurate hypocenter determination is crucial for seismic hazard analysis, delineating faults, and elucidating seismic source characteristics. However, hypocenters determined using an inaccurate velocity model can exhibit significant deviations from the actual hypocenter. In this study, we investigated how a 3-D velocity model results in a better constraint than a 1-D model for the hypocenter determination problem associated with the 2017 MW 5.5 Pohang earthquake. This study determined the hypocenter of the Pohang earthquake sequence using a 3-D velocity model of 32 events including the mainshock that occurred on November {vn15}, 2017, in South Korea. The S wave velocity model, based on an ambient noise tomography, was combined with the average Vp/Vs ratio of the crust of the Korean Peninsula to construct a 3-D velocity model; additional 1-D velocity model was used to compare the results. The hypocenters were determined via a nonlinear method, which allowed the calculation of the posterior probability density of the source via a direct search method, confirming that the accuracy improved when using the 3-D model compared with the 1-D model. We observed that our 3-D velocity model enables hypocenters to be consistently determined, less affected by station configuration, or a lack of adjacent seismic stations. Further numerical investigation showed that complex basin geometry and the heterogeneity of the crustal thickness, which cannot be considered in 1-D model, are critical for hypocenter determination.
      PubDate: 2022-08-01
       
  • Determination of new national groundwater monitoring sites using
           artificial neural network model in South Korea

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      Abstract: Abstract South Koreas National Groundwater Monitoring Network (NGMN) was installed during the early 1990s to detect the trends in groundwater levels; however, a revised NGMN plan is required in consideration of climate change and human activities. Linear trend analyses of the groundwater levels, Cl concentration, and NO3-N concentration of 521 monitoring wells were conducted to define the downward and upward trends. The attributes of 14 items relating to topography, stream proximity, land use, soil, hydrogeology, and well density were extracted from thematic maps for each monitoring site. An artificial neural network (ANN) model for groundwater level trends was developed using these 14 input variables to predict the downward (output variable: 1) and non-downward (output variable: 0) trends at any grid point in a standard watershed. Candidate sites for new groundwater monitoring wells were suggested based on the probability of the existence of two trends for groundwater levels. Candidate sites were excluded if they showed upward trends of Cl and NO3-N because the primary objective of the NGMN was not to observe changes in water quality but to observe the background conditions of water quality. It was proposed to install a total of 1475 groundwater monitoring wells (existing plus new wells) by 2045, and the percentage contributions of non-downward and downward trends of groundwater levels to the total number of trends (i.e., wells) were projected to be 61.5% and 38.5%, respectively. The NGMN will play an important role in recognizing climate change, observing groundwater level declines caused by human activities, and assessing the relationship between surface water and groundwater in standard watersheds.
      PubDate: 2022-08-01
       
  • Multiple and single grain quartz OSL dating of dolmens in Jungdo, central
           Korean Peninsula

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      Abstract: Abstract In the last few years, substantial amount of archaeological remains, which belong to the Bronze and the Iron Ages, has been excavated in Jungdo, central part of Korean peninsula, indicating that the prehistoric (partly, early historic) cultures had been flourished in this area. Particularly, more than 150 dolmens were found during the excavation campaign, and they have drawn keen attentions because dolmens are controversially regarded as being the representative remains for the Bronze Age in Korean peninsula. Despite their archaeological importance for understanding the ancient cultural and social aspects in Korean peninsula, the chronology of the dolmens has largely been dependent upon sensory tests using concomitant artifacts while numerical dating has been scarce and limited to the case when organic materials for radiocarbon dating were available. Recent advances in luminescence dating, however, allow direct dating of stone structures, like dolmens, by measuring OSL (Optically Stimulated Luminescence) signals in phosphor minerals underneath the stone structures. In this paper, we performed OSL dating of quartz collected from underneath the stones making up dolmens in Jungdo. For OSL dating, we chose three dolmens and six sediment samples were collected from them. Using multiple grain aliquots, consisting of ∼300 quartz grains, the OSL ages of ∼4.3–3.2 ka were obtained. These ages, however, appear to be older than previously reported radiocarbon ages in Jungdo and a radiocarbon age (2119–1750 cal yr BP) of a human bone sample excavated from one of the dolmens. On the contrary, single grain OSL dating yielded MAM-3 (Minimum Age Model with three parameters) ages consistent with the radiocarbon age, ranging ∼2.9–2.2 ka. Our results suggest that Jungdo has been the place either for burial plots or habitation of the ancient humans up to early Iron Age in the central part of Korean peninsula.
      PubDate: 2022-08-01
       
  • Seismological characteristics of microearthquake sequence near Suncheon,
           South Korea, from 2009 to 2020

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      Abstract: Abstract We analyzed the seismological characteristics of a microearthquake sequence that occurred from September 2009 to August 2020 with epicenters concentrated within a small area, ∼10 km WNW of downtown Suncheon, South Korea. During the study period, 33 events with a local magnitude (ML) < 2.0 were cataloged by the Korea Meteorological Administration. We identified 101 uncataloged events in the source region by using the matched filter method and estimated magnitudes based on amplitude ratios measured with a reference event. The focal mechanism solutions of 16 events were obtained with P-wave polarities and S-wave to P-wave amplitude ratios, which were used in iterative stress inversion to estimate the current stress orientation. The hypocenters of this sequence were relocated using the double-difference method. A total of 133 relocated microearthquakes were aligned at ∼11 km depth along a 500 m long lineation with an azimuth of N80°E and a dip of 84°N. This matched very well with the principal focal mechanism from the stress inversion of 16 focal mechanism solutions, striking N77°E with a dip of 88°N. The maximum principal stress direction of the Suncheon microearthquake sequence was a trend of NE-SW, slightly different from the regional tectonic stress in the eastern Eurasian plate, which may imply the existence of local stress perturbations in the study area.
      PubDate: 2022-07-14
       
  • Outcrop modeling of flow units and reductant within a sandstone uranium
           reservoir in the Zhiluo Formation, eastern Ordos Basin: implications for
           the uranium mineralization mechanism

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      Abstract: Abstract The spatial distribution of flow units and reductant within a sandstone uranium reservoir is very beneficial for exploring the uranium mineralization mechanism; however, such studies have been almost neglected. As such, this paper aims to provide the sedimentological interpretation and heterogeneity models of the sandstone of the Middle Jurassic Zhiluo Formation at Shiwan outcrop area, in the eastern Ordos Basin. The outcrops are sandstone-dominated subaqueous distributary channel successions, in which five distinct architectural elements are identified and interpreted: channel units (CU), downstream accretion elements (DA), lateral accretion elements (LA), sandy bedforms (SB) and no-channelized fine-grained sediments (NFS). Within the sandstone succession, six flow units are present in the middle and lower parts of CU, or the lower parts of DA and SB elements, with their geometry to be controlled by the fourth- or third-order bounding surfaces. Moreover, the carbonaceous debris-rich zones (CDZ) are places with the highest abundance of reductant and preserve exclusively upon the basal erosional surfaces of CU and DA elements. Based on those results, a prediction model is established and shows that the formation of interlayer oxidation zone is strongly selective and confined within the CU and DA elements. The favorable site of uranium mineralization is preferentially distributed in the transition zone between the front of flow unit and the CDZ.
      PubDate: 2022-06-27
       
  • An optimal strategy for determining triple oxygen isotope ratios in
           natural water using a commercial cavity ring-down spectrometer

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      Abstract: Abstract Triple oxygen isotope ratios have been increasingly acknowledged as useful hydrological tracers but measuring both 17O/16O and 18O/16O ratios with meaningful precision has been challenging due to the much lower natural abundance of 17O than 16O and even 18O. In this study, in line with the advancement of laser-based techniques and their growing applications, we demonstrate how to optimize the determination of 17O-excess (Δ17O = ln(δ17O + 1) − 0.528 × ln(δ18O + 1)) in natural water using a commercial wavelength-scanned cavity ring-down spectrometer (WS-CRDS). We particularly focus on how to decide the injection numbers of samples and standard solutions utilized for normalization of sample results to the VSMOW-SLAP reference scale. With a measurement strategy aimed at an uncertainty better than 10 per meg (1σ), the Δ17O of Greenland Ice Sheet Precipitation (GISP) is determined to be 24 ± 9 per meg (n = 104), in agreement with previous literature values. By applying this method to Antarctic glacial ice, it is shown to be useful in detecting the seasonality of Δ17O values in Antarctic precipitation. Our approach represents an underlying analytical method that provides guidelines for determining Δ17O from various types of natural waters.
      PubDate: 2022-06-27
       
  • Integrated geophysical and geochemical investigations on the high-salinity
           geothermal waters of the Khlong Thom Hot Spring tourist attraction in
           Krabi, southern Thailand

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      Abstract: Abstract The Krabi saline hot spring (Khlong Thom Hot Spring) located in southern Thailand has been recognized as a unique geothermal spring attraction due to its high-salinity geothermal groundwater. Studies have been performed to understand the mechanisms of saltwater intrusion into the geothermal aquifers. However, little is known about how the high-salinity groundwater affects the local geological structures, geological materials, and groundwater aquifers. Therefore, we performed integrated geological well measurements, geophysical electrical resistivity tomography (ERT) surveys, and geochemical analyses for major ions (cations and anions) and geothermometers (silica and cation) to investigate the local geological settings and the sources of salinity in the Krabi saline geothermal system. The water samples from the natural hot spring pools and geothermal wells were uniformly of the Cl−−Na+ type with high total dissolved solids (TDS) contents ranging from 12,663 to 15,180 mg/L, but the nongeothermal water was considered to be shallow groundwater of the Na+−HCO3− type with lower TDS contents. Once the trapped saltwater intruded into the wetlands (salt-marshes), its chemical composition was modified by the freshwater/groundwater mixing processes active in the development of shallow geothermal reservoirs. However, a silica-quartz geothermometer was utilized, and the calculated reservoir temperatures ranged from 83 to 86 °C, unlike the cation and silica-chalcedony geothermometers, which were not likely to be applicable for estimating reservoir temperatures in this geothermal system. Moreover, the ion ratios indicated that the water-rock interactions occurring within the geothermal reservoir, mostly related to its nonequilibrium state, might have little effect on the quality of the geothermal groundwater. ERT interpretation was carried out to compare the characteristics of the geological materials obtained directly from the geothermal wells with their apparent resistivity values corresponding to the obtained 2D-ERT profiles. Low resistivity values, ranging from 1 to 10 Ω-m, may have arisen from the dominating influence of the freshly mixed saltwater, which mainly originated via saltwater intrusion into the shallow aquifer on the study site. Therefore, 2D-ERT can be highly useful for detecting changes in thickness and detecting the presence of local faults in the Krabi saline geothermal field. In comparison, geothermal water rose to the surface due to local faults and this finding was well associated with a tectonic junction of the Krabi geological setting. These research findings suggest that governmental agencies should consider combining the results from academic geoscience studies with business objectives to develop a sustainable developmental plan for the geothermal spring attractions of Thailand.
      PubDate: 2022-06-27
       
  • The Jangsan Formation refined

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      Abstract: Abstract Formation comprises a distinctive set of sedimentary layers, which can be traceable laterally and mapped as a unit. It is a fundamental unit for stratigraphic position in a regional scale and provides an important basis for the interpretation of depositional processes and environments. This paper reviews the occurrence of the Jangsan Formation at the base of the Taebaek Group (Cambrian-Ordovician) in the Taebaeksan Basin and refines the geologic map unit for sedimentary characteristics and stratigraphic position. The refined Jangsan Formation comprises a set of distinctive sandstone (quartzite) with a number of sedimentary facies, including conglomerate, conglomeratic sandstone, and mudstone. The “Myeonsan Formation” is limited to a localized set, and leads it fallen into disuse. The refined Jangsan Formation can be reliably correlated with the equivalent early Cambrian sandstone unit (Liguan Formation) in Shandong Province, China about a thousand kilometers apart and elsewhere in the northeast Asian continent.
      PubDate: 2022-06-09
       
  • Redlichia nobilis Walcott, 1905, the oldest trilobite in South Korea: age
           and morphologic restoration by strain analysis

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      Abstract: Abstract Redlichia nobilis Walcott, 1905 occurs in the Gurangri Formation of the Mungyeong Group, a lithostratigraphic unit of the Cambrian-Ordovician Joseon Supergroup in the Taebaeksan Basin, South Korea. The R. nobilis Zone of the formation is correlated with the Lungwangmiaoan Stage and the middle part of the Duyunian Stage of North and South China regional chronostratigraphic scheme, respectively. It corresponds to middle Stage 4 of Cambrian Series 2 in international chronostratigraphic chart. R. nobilis, which is regarded as the oldest trilobite in South Korea, is estimated to be 512 to 510.4 million years old. The specimens of R. nobilis are preserved on the bedding plane as deformed due to structural movement occurred in the Mungyeong area. It is observed in the outcrop that the cleavage plane intersects the bedding plane almost at right angle, forming intersection lineation parallel to fold axis. The cleavage plane can be generally defined as the XY plane and the lineation as the Y axis of strain ellipse on the bedding plane, and thus, the bedding plane corresponds to the YZ plane. The strain analysis using Mohr circle was performed to estimate strain ratio of the deformed specimens. Strain ratio (R) of the deformed specimens calculated ranges from 2.18 to 2.20, with the average of 2.19. The value is considered strongly reliable because the strain ratio of a combined strain marker consisting of a deformed specimen and elliptical structure (probably concretion) around the specimen is 2.18, nearly identical to the R values of other deformed specimens. Morphologic restoration of shape and size was conducted under no longitudinal strain along Y axis because structures indicative of stretching or shortening along the lineation are not observed in the outcrop and those indicative of shortening along the Z axis and thickening along the X axis are observed in thin section. The deformed specimens were restored into an undeformed state using a digital graphic software by only applying the R value perpendicular to the lineation for each specimen. R. nobilis, based on its restored morphology, is characterized by having anteriorly diagonal preocular sutures that are about 120% more apart than palpebral sutures, a hypostome that is fused with rostral plate and has two pairs of short spines (one pair along the lateral margin and the other at postero-lateral corner), 15 thoracic segments with a long axial spine on the 11th (from the anterior) segment, and a small sub-elliptical pygidium with three axial rings and sagittal furrow.
      PubDate: 2022-06-01
      DOI: 10.1007/s12303-021-0036-0
       
  • Estimation of shallow S-wave structures from the quasi-transfer spectrum
           and Bayesian inversion using microarray data at a deep drilling site at
           Chungnam National University, Korea

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      Abstract: Abstract Estimating shallow S-wave structures is crucial for assessing the level of strong ground motion amplification. In this study, we applied a transdimensional and hierarchical Bayesian inversion to surface wave dispersions obtained from a passive f-k analysis of geophone microarray data. The dispersion data obtained from the microarray f-k analysis have uncertainties resulting from array conditions, possibly including subsurface lateral heterogeneities, array sizes, source distributions, and measurement lengths. The Bayesian approach provides complete posterior probability distributions of model parameters, enabling a robust investigation that explains the uncertainties. Moreover, the results from a quasi-transfer spectrum (QTS) analysis and geological core information were used during the interpretation of our inversion results. Ambient noise data were collected at a deep drilling site at Chungnam National University, South Korea. The estimated S-wave structure indicated a rapid transition in velocity increase at depths of 4–30 m from ∼ 200 m/s to ∼ 3,600 m/s, corresponding to a rapid variation from sandy soil to hard rock in the core samples. Despite relatively less constrained features, the QTS peak frequencies provided a reliable range of bedrock-depth estimations. We also tested and compared dispersion data and noise characteristics with different array configurations in time and space to better understand possible causes of data variations and present a practical guideline for future experiments in sites with similar conditions. Together with possible effects on dispersion data due to the variability, this study shows a comprehensive procedure to interpret shallow S-wave structures and their uncertainties accounting for the data uncertainties throughout the Bayesian inversions.
      PubDate: 2022-06-01
      DOI: 10.1007/s12303-021-0034-2
       
  • An advanced mixed Lagrangian-Eulerian and finite element method to
           simulate 3-D subsurface variably saturated flows

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      Abstract: Abstract This study proposes an advanced, efficient numerical solution involving the use of the mixed Lagrangian-Eulerian (LE) method and the finite element method (FEM) for producing 3D simulations of variably saturated subsurface flow as described by Richards’ equation. The LE approach with its particle tracking algorithm was selected for the resolution of numerical problems resulting from the penetration of a sharp front through flux boundaries during the infiltration process. In this new approach, the LE method is applied to interior nodes, and the FEM is applied to incoming-flux-boundary nodes. The proposed numerical scheme is implemented by first obtaining proper matrix equations for the boundary nodes in order to analyze flow behaviors in saturated/unsaturated porous media. In order to demonstrate the performance of the proposed algorithm, four examples are provided; the one-dimensional single- and multi-layered soil column problem, a three-dimensional drainage problem and a three-dimensional pumping well problem. In the four examples, the mixed LE and FEM method (MLE) using relatively large time steps obtained superior results in terms of the accuracy and computational efficiency in comparison with the conventional FEM. The outcome of the proposed study will contribute to efficient numerical solution for subsurface flow problems involving critical boundary conditions in real watershed.
      PubDate: 2022-06-01
      DOI: 10.1007/s12303-021-0039-x
       
  • Basin deformation history deduced from shelf break and growth strata in
           the southern Ulleung Basin, East Sea (Japan Sea)

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      Abstract: Abstract Previous studies about tectonic events in the Ulleung Basin have been performed using diverse methods, but the deformation history of the Ulleung Basin is still controversial. In the Ulleung Basin, the Dolgorae and Gorae I structures were formed by basin deformation I (northwest-southeast compression) and the Gorae V structure was formed by basin deformation II (east-west compression). Since the quality of seismic data of the Dolgorae structures is not good, it is more difficult to reveal the basin deformation history through structural analysis of the seismic data. Thus, we traced the change in paleo-shelf breaks and studied provenance using image logs as indirect tectonic evidence and analyzed the growth strata of the Dolgorae and Gorae structures using seismic data for analyzing basin deformation. The shape of the paleo-shelf break has changed from linear to curved shape since 12.5 Ma, and the progradation rate of the paleo-shelf break was the fastest during 10.6–12.5 Ma. Before 12.5 Ma, sediments were supplied in the southwest direction, but after 12.5 Ma, they were supplied in the southeast direction originated from uplifted Dolgorae thrust fault zone. This evidence imply that basin deformation occurred in 12.5 Ma. During basin deformation I, the Gorae I structure was formed later than the Dolgorae structures due to the propagation of compression, and during basin deformation II, the Gorae V structure was formed from 5.33 Ma based on analysis of growth strata.
      PubDate: 2022-05-20
      DOI: 10.1007/s12303-022-0005-2
       
  • Distribution characteristics and processes along flow paths of shallow
           groundwater in the Tan-Lu fault zone in Anhui province, China

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      Abstract: Abstract To disclose the distribution characteristics, the situation of flow and storage, and processes along flow paths of shallow groundwater in Tan-Lu fault zones, nine hundred and seven groundwater table elevations data and one hundred hydrochemical samples of shallow groundwater were taken from the Tan-Lu fault zone in Anhui province to analyze the characteristic of groundwater distribution. The geographic information system (GIS) method was used to analyze the spatial distribution characteristics of groundwater tables, total dissolved solids (TDS) and chloride ion (Cl−). Geophysical prospecting, drilling material and regional hydrogeological survey were utilized to disclose groundwater storage and flow regime in the fault zone. The results show that the Tan-Lu fault zone in Anhui province has controlled groundwater flow into the Jiashan basin, Hefei basin, Chaohu area and Qianshan basin, which developed from north to south in this area. Groundwater in theses basins have recharged from surrounding areas to form a water storage space. Geophysical prospecting and drilling technology revealed that the Tan-Lu fault zone provided a flow channel and storage space for ground-water. Faults provide preferential channels in some areas for the groundwater flow and circulation, eventually deep hot-water flows upward and discharges in the form of hot-springs. The identification of the groundwater flow pathway can help to provide a reliable scientific basis for regional spatial development and utilization of groundwater resources.
      PubDate: 2022-05-17
      DOI: 10.1007/s12303-022-0004-3
       
  • Spatial variations of authigenic beryllium isotopes in surface sediments
           of the Antarctic oceans: a proxy for sea ice dynamics and sedimentary
           environments

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      Abstract: Abstract This study documents spatial variations in authigenic 9Be and 10Be concentrations and 10Be/9Be ratios in different glacial settings in the Weddell and Ross seas, Antarctica. Weddell Sea surface sediments have the lowest 10Be and highest 9Be concentrations, and most depleted 10Be/9Be ratios, as compared with other regions, indicating 9Be enrichment from the recently collapsed Larsen Ice Shelf (LIS) B and reduction of 10Be supply due to blockage by the un-deglaciated LIS C. Local 10Be deposition varies across the open marine Ross Sea, which is more affected by seasonal sea ice persistence than ocean currents. Higher 10Be/9Be ratios in the western Ross Sea and higher 10Be concentrations in the eastern Ross Sea correlate with higher sea ice concentrations and changes, and vice versa in the central Ross Sea. The higher sea ice concentration not only blocks atmospheric 10Be and dust deposition during the frozen season, but increases the dust flux and supply of Be isotopes during the sea ice melting season. Thus, the spatial distribution of Be isotopes in surface sediments of the Antarctic oceans can be used as a proxy for sea ice dynamics and sedimentary environments.
      PubDate: 2022-05-17
      DOI: 10.1007/s12303-022-0003-4
       
  • Geochemical characteristics of sediments from East Dongting Lake and their
           implications for provenance and weathering

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      Abstract: Abstract Dongting Lake is the second-largest freshwater lake in China. To better understand the geochemical characteristics of the sediment in different seasons and identify the possible provenance, 44 sediment samples collected from East Dongting Lake (ED Lake) in summer (ED-S) and winter (ED-W) were used for elemental geochemical analysis. Geochemically, the sediment samples are classified as shale, and the chondrite normalized rare earth element (REE) patterns of the ED-S and ED-W have light REE (LREE) enriched, flat heavy REE (HREE) patterns with a negative Eu anomaly. In the present study, the correlations between certain elements show that the variations in ΣREE contents in sediments may be due to the concentrations of heavy minerals like monazite, whereas grain size is not responsible for that variations. Chemical index of alteration (CIA), plagioclase index of alteration (PIA) values, A-CN-K diagram, and Th/U ratios of the ED-S and ED-W sediment indicate a moderate to high intensity of chemical weathering in the source area. The Al2O3/TiO2 ratio, discriminant function diagram, REE patterns, and elemental ratios indicate the contribution of sediments from felsic and intermediate source rocks. The provenance index (PI) based on REEs geochemical parameters suggest that elemental compositions of sediment in East Dongting Lake approach the Upper Yangtze River.
      PubDate: 2022-02-15
      DOI: 10.1007/s12303-021-0040-4
       
 
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