I. Feichtinger, J. Pollerspöck, Mathias Harzhauser, Gerald Auer, M. Kranner, G. Guinot
Extensive bulk-sampling of the continuous Cretaceous-Paleogene boundary section at Gams (Styria, Austria) allows for the first time the description of the elasmobranch communities inhabiting the bathyal environment of this well-known section. The sampled succession comprises six horizons from the uppermost Maastrichtian (upper part of Nephrolites frequens Zone CC26) and five horizons from the lowermost Danian (Zone NP1), which yielded a total of 1852 elasmobranch teeth. Although the majority of the teeth are not well preserved, this study enabled the description of at least 16 taxa of the orders Hexanchiformes, Squaliformes, Orectolobiformes, Lamniformes and Carcharhiniformes, providing a rare snapshot of elasmobranch diversity of this specific environmental setting. Beside minor diversity fluctuations between the assemblages, the extensive bulk-sampling of this section did not reveal a marked diversity decline related to the end-Cretaceous mass extinction event. However, a noteworthy correlation between the deepening upward trend of the section with the appearance of frilled and goblin sharks points to changes in palaeobathymetry, which is also reflected in the increase of the total proportion of squaliform teeth in the uppermost sampled horizon. Furthermore, teeth of the extinct triakid Palaeogaleus were recovered exclusively from the Danian deeper deposits, expanding the palaeoecological range of the genus down to fairly deep marine environments. In addition, this study provides the first record of the lamniform Cretolamna ex gr. borealis from the Danian of the Tethyan Realm expanding the palaeogeographic distribution of this group.
对加姆斯（奥地利施蒂里亚州）白垩纪-古近纪连续边界断面进行了大量取样，首次描述了这一著名断面水深环境中的伶支动物群落。取样的演替包括来自最上层马斯特里赫特期（Nephrolites frequens 上部的 CC26 区）的六个地层和来自最下层但尼尔期（NP1 区）的五个地层，共发现了 1852 枚鞘鳃类牙齿。虽然大部分牙齿保存不全，但这项研究描述了至少 16 个分类群，包括六形目、鱿形目、直齿目、榄形目和箭形目，为这一特定环境中的箭形目多样性提供了难得的快照。除了各组合之间的微小多样性波动外，对该剖面的大量取样并未发现与白垩纪末大灭绝事件有关的明显的多样性下降。不过，值得注意的是，该剖面向上加深的趋势与流苏鲨和麒麟鲨的出现之间存在关联，这表明古生物测定发生了变化，这也反映在最上层取样地层中鳞状牙齿总比例的增加上。此外，已灭绝的三足鲨 Palaeogaleus 的牙齿仅在达尼安深层沉积中发现，从而将该属的古生态范围扩大到相当深的海洋环境。此外，该研究还首次记录了特提安海域大尼安河流域的薄片形动物 Cretolamna ex gr. borealis，扩大了该类动物的古地理分布范围。
{"title":"Elasmobranch assemblages from a bathyal environment spanning the Cretaceous-Paleogene boundary in Austria","authors":"I. Feichtinger, J. Pollerspöck, Mathias Harzhauser, Gerald Auer, M. Kranner, G. Guinot","doi":"10.17738/ajes.2024.0001","DOIUrl":"https://doi.org/10.17738/ajes.2024.0001","url":null,"abstract":"\u0000 Extensive bulk-sampling of the continuous Cretaceous-Paleogene boundary section at Gams (Styria, Austria) allows for the first time the description of the elasmobranch communities inhabiting the bathyal environment of this well-known section. The sampled succession comprises six horizons from the uppermost Maastrichtian (upper part of Nephrolites frequens Zone CC26) and five horizons from the lowermost Danian (Zone NP1), which yielded a total of 1852 elasmobranch teeth. Although the majority of the teeth are not well preserved, this study enabled the description of at least 16 taxa of the orders Hexanchiformes, Squaliformes, Orectolobiformes, Lamniformes and Carcharhiniformes, providing a rare snapshot of elasmobranch diversity of this specific environmental setting. Beside minor diversity fluctuations between the assemblages, the extensive bulk-sampling of this section did not reveal a marked diversity decline related to the end-Cretaceous mass extinction event. However, a noteworthy correlation between the deepening upward trend of the section with the appearance of frilled and goblin sharks points to changes in palaeobathymetry, which is also reflected in the increase of the total proportion of squaliform teeth in the uppermost sampled horizon. Furthermore, teeth of the extinct triakid Palaeogaleus were recovered exclusively from the Danian deeper deposits, expanding the palaeoecological range of the genus down to fairly deep marine environments. In addition, this study provides the first record of the lamniform Cretolamna ex gr. borealis from the Danian of the Tethyan Realm expanding the palaeogeographic distribution of this group.","PeriodicalId":55415,"journal":{"name":"Austrian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140526827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ophiolites are remnants of oceanic crust and mantle, now typically found within continental mountain ranges like the Alps. Particularly in areas once part of the Tethys Ocean, ophiolites are often accompanied by narrow stripes of metamorphic rocks, commonly referred to as metamorphic soles. These metamorphic soles typically exhibit peak metamorphic conditions characteristic of either granulite or amphibolite facies. Geochronological studies of Tethyan ophiolites indicate that the development of these metamorphic soles occurred almost simultaneously with the crystallization of the ophiolite’s crustal sequence. Geological evidence also suggests that the metamorphism of the sole rocks took place concurrently with deformation, likely at the same time as the ophiolite’s obduction. In our research, we explore the metamorphic effects of shearing in an ophiolite sequence overlying a crustal sequence. Our findings reveal that strong lithologies like ophiolites can produce additional heat through the dissipation of mechanical energy, which can potentially explain the high temperatures found in metamorphic-sole rocks. In addition, heating-driven softening of the footwall rocks eventually leads to the migration of the active shear zone from the mantle sequence into the upper crustal domain. This migration may be responsible for the metamorphic sole incorporation at the base of the ophiolite. Finally, we demonstrate that stopping the shearing process rapidly cools these rocks, corresponding with the findings from thermochronological studies from Oman ophiolite.
{"title":"A thermo-mechanical model of the thermal evolution and incorporation of metamorphic soles in Tethyan ophiolites: a case study from Oman","authors":"Iskander Ibragimov, Daniel Kiss, E. Moulas","doi":"10.17738/ajes.2024.0002","DOIUrl":"https://doi.org/10.17738/ajes.2024.0002","url":null,"abstract":"\u0000 Ophiolites are remnants of oceanic crust and mantle, now typically found within continental mountain ranges like the Alps. Particularly in areas once part of the Tethys Ocean, ophiolites are often accompanied by narrow stripes of metamorphic rocks, commonly referred to as metamorphic soles. These metamorphic soles typically exhibit peak metamorphic conditions characteristic of either granulite or amphibolite facies. Geochronological studies of Tethyan ophiolites indicate that the development of these metamorphic soles occurred almost simultaneously with the crystallization of the ophiolite’s crustal sequence. Geological evidence also suggests that the metamorphism of the sole rocks took place concurrently with deformation, likely at the same time as the ophiolite’s obduction. In our research, we explore the metamorphic effects of shearing in an ophiolite sequence overlying a crustal sequence. Our findings reveal that strong lithologies like ophiolites can produce additional heat through the dissipation of mechanical energy, which can potentially explain the high temperatures found in metamorphic-sole rocks. In addition, heating-driven softening of the footwall rocks eventually leads to the migration of the active shear zone from the mantle sequence into the upper crustal domain. This migration may be responsible for the metamorphic sole incorporation at the base of the ophiolite. Finally, we demonstrate that stopping the shearing process rapidly cools these rocks, corresponding with the findings from thermochronological studies from Oman ophiolite.","PeriodicalId":55415,"journal":{"name":"Austrian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140522413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recently, samples of natrochalcite, NaCu2(SO4)2∙H3O2, were discovered from the Esperanza Mine, Lavrion Mining District, Greece. In the present study this material is characterized by single crystal X-ray diffraction at ambient and LT conditions. Natrochalcite is monoclinic, space group C2/m, with a = 8.809(2), b = 6.196(1), c = 7.504(2) Å, β = 118.56(3)°, V = 359.7(1) Å3, Z = 2, R1 = 0.0195 at room temperature. No symmetry change was observed down to 100K.
{"title":"Natrochalcite NaCu2(SO4)2∙H3O2 from the Lavrion Mining District – a brief characterisation","authors":"Gerald Giester, B. Rieck","doi":"10.17738/ajes.2024.0004","DOIUrl":"https://doi.org/10.17738/ajes.2024.0004","url":null,"abstract":"\u0000 Recently, samples of natrochalcite, NaCu2(SO4)2∙H3O2, were discovered from the Esperanza Mine, Lavrion Mining District, Greece. In the present study this material is characterized by single crystal X-ray diffraction at ambient and LT conditions. Natrochalcite is monoclinic, space group C2/m, with a = 8.809(2), b = 6.196(1), c = 7.504(2) Å, β = 118.56(3)°, V = 359.7(1) Å3, Z = 2, R1 = 0.0195 at room temperature. No symmetry change was observed down to 100K.","PeriodicalId":55415,"journal":{"name":"Austrian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140519068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Annika Geringer, C. Iglseder, Urs Klötzli, Bernhard Grasemann, Jiří Sláma
In the 1980s, large parts of the Bohemian Massif in Austria were explored for the occurrence of raw materials (Göd, 1988), and a trace content of topaz was discovered in channels draining the eastern slope of the Ostrong (Lower Austria). Orthogneiss bodies in the Ostrong Nappe System are shown to be the source of these topaz occurrences, and Raman spectroscopy indicates that topaz is fluorine rich. So far, this is the only occurrence of topaz-bearing orthogneiss within the entire Moldanubian Superunit. The orthogneiss shows a tectonic overprint and exhibits a weak to well-developed foliation, as well as local folding. Samples taken near the tectonic boundary of the Ostrong to the Drosendorf Nappe Systems show stronger shear deformation with a pronounced mylonitic foliation and stretching lineation. Detailed geo-chemical investigations of the major and trace elements indicate a classification as S-type granite with a high degree of differentiation and a peraluminous character. The orthogneiss has a high SiO2 content of 72.8–77.3 wt%, as well as a noteworthy high fluorine content of up to 2760 ppm. Mineral compositions show zoned plagioclase with an albite component of about 87–99 mol%, increasing towards the grain margin. Garnet occurs rarely, but consistently in those samples near the tectonic boundary of the Ostrong- to the Drosendorf Nappe Systems. Garnet is almandine-dominated, shows no zoning and is single-phased. Sillimanite is common and samples near the tectonic boundary also contain kyanite. To determine the previously unknown protolith age of the orthogneiss, U-Pb zircon dating was applied. Three zircon fractions from two samples yield concordia ages of 475.3 ± 1.0 Ma, 474.8 ± 2.9 Ma, and 473.5 ± 1.5 Ma, identical in assigned uncertainties, reflecting magmatic zircon growth. Furthermore, the short prismatic habit of zircon grains indicates a plutonic rather than volcanic origin of the protolith. Dating results also provide a minimum sedimentation age for the rocks of the Ostrong Nappe System within Austria. In comparison with other metagranitoids and orthogneisses of the Moldanubian Nappes, the investigated orthogneiss shows strong similarities with the Gföhl Gneiss and the Moldanubian Granulite. The orthogneiss therefore is considered as a more fractionated equivalent of the Gföhl Gneiss. In conclusion we suggest to name the studied orthogneiss Laimbach Orthogneiss in the rank of a lithodeme (NACSN, 2005), after the locality Laimbach am Ostrong (48°19′01″N; 15°07′19″E), which is located centrally with respect to the occurrences of this gneiss.
{"title":"Topaz-bearing Lower Ordovician orthogneiss within the Ostrong Nappe System – The Laimbach Orthogneiss (Bohemian Massif, Lower Austria)","authors":"Annika Geringer, C. Iglseder, Urs Klötzli, Bernhard Grasemann, Jiří Sláma","doi":"10.17738/ajes.2024.0003","DOIUrl":"https://doi.org/10.17738/ajes.2024.0003","url":null,"abstract":"\u0000 In the 1980s, large parts of the Bohemian Massif in Austria were explored for the occurrence of raw materials (Göd, 1988), and a trace content of topaz was discovered in channels draining the eastern slope of the Ostrong (Lower Austria). Orthogneiss bodies in the Ostrong Nappe System are shown to be the source of these topaz occurrences, and Raman spectroscopy indicates that topaz is fluorine rich. So far, this is the only occurrence of topaz-bearing orthogneiss within the entire Moldanubian Superunit. The orthogneiss shows a tectonic overprint and exhibits a weak to well-developed foliation, as well as local folding. Samples taken near the tectonic boundary of the Ostrong to the Drosendorf Nappe Systems show stronger shear deformation with a pronounced mylonitic foliation and stretching lineation. Detailed geo-chemical investigations of the major and trace elements indicate a classification as S-type granite with a high degree of differentiation and a peraluminous character. The orthogneiss has a high SiO2 content of 72.8–77.3 wt%, as well as a noteworthy high fluorine content of up to 2760 ppm. Mineral compositions show zoned plagioclase with an albite component of about 87–99 mol%, increasing towards the grain margin. Garnet occurs rarely, but consistently in those samples near the tectonic boundary of the Ostrong- to the Drosendorf Nappe Systems. Garnet is almandine-dominated, shows no zoning and is single-phased. Sillimanite is common and samples near the tectonic boundary also contain kyanite. To determine the previously unknown protolith age of the orthogneiss, U-Pb zircon dating was applied. Three zircon fractions from two samples yield concordia ages of 475.3 ± 1.0 Ma, 474.8 ± 2.9 Ma, and 473.5 ± 1.5 Ma, identical in assigned uncertainties, reflecting magmatic zircon growth. Furthermore, the short prismatic habit of zircon grains indicates a plutonic rather than volcanic origin of the protolith. Dating results also provide a minimum sedimentation age for the rocks of the Ostrong Nappe System within Austria. In comparison with other metagranitoids and orthogneisses of the Moldanubian Nappes, the investigated orthogneiss shows strong similarities with the Gföhl Gneiss and the Moldanubian Granulite. The orthogneiss therefore is considered as a more fractionated equivalent of the Gföhl Gneiss. In conclusion we suggest to name the studied orthogneiss Laimbach Orthogneiss in the rank of a lithodeme (NACSN, 2005), after the locality Laimbach am Ostrong (48°19′01″N; 15°07′19″E), which is located centrally with respect to the occurrences of this gneiss.","PeriodicalId":55415,"journal":{"name":"Austrian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140521292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Karst springs play a central role in Austria’s water supply. This paper aims to provide an overview of the karst springs of Lower Austria, analysing statistical correlations of spatial distribution, discharge, electrical conductivity (EC), and temperature. As part of a project with the provincial government of Lower Austria, older data from numerous studies have been combined with the self-generated data in a GIS database. This database contains data on 2056 karst springs. Most of the recorded springs are located in the Northern Calcareous Alps, although karst springs also occur in the Central Alpine Permomesozoic, the Waschberg zone and the Bohemian Massif, some of which are also of regional importance for drinking water supply. Chemical analyses show that limestone, dolomite and mixed springs are widespread in Lower Austria and occur with similar frequency. Gypsum springs, which are characterised by a significantly higher total mineral-isation, are also of regional importance. The statistical analysis shows that spring water temperatures correlate well with the mean annual air temperature at the mean catchment elevation. The temperature decrease with increasing elevation corresponds to the air temperature gradient in the Eastern Alps (0.47 °C/100 m). In addition, the springs show a negative correlation of the EC with the mean catchment elevation, which can be explained by a decrease in soil cover and thus reduced CO 2 uptake of the water, as well as dilution by rainwater. This leads to less carbonate dissolution, which is also reflected in less HCO 3 − contents. Corrected for the elevation effect, the investigated dolomite springs, have on average a 2.7% higher EC than limestone springs. A difference was also found between the Hauptdolomit and the Wettersteindolomit rock types, which are widespread in Lower Austria, with the latter displaying higher values on average by 2.2%. This indicates longer residence times of the spring water due to less karstification of the Wettersteindolomit.
{"title":"Statistical analysis of karst springs in Lower Austria","authors":"Clemens Schmalfuss, Lukas Plan, Rudolf Pavuza","doi":"10.17738/ajes.2023.0007","DOIUrl":"https://doi.org/10.17738/ajes.2023.0007","url":null,"abstract":"Abstract Karst springs play a central role in Austria’s water supply. This paper aims to provide an overview of the karst springs of Lower Austria, analysing statistical correlations of spatial distribution, discharge, electrical conductivity (EC), and temperature. As part of a project with the provincial government of Lower Austria, older data from numerous studies have been combined with the self-generated data in a GIS database. This database contains data on 2056 karst springs. Most of the recorded springs are located in the Northern Calcareous Alps, although karst springs also occur in the Central Alpine Permomesozoic, the Waschberg zone and the Bohemian Massif, some of which are also of regional importance for drinking water supply. Chemical analyses show that limestone, dolomite and mixed springs are widespread in Lower Austria and occur with similar frequency. Gypsum springs, which are characterised by a significantly higher total mineral-isation, are also of regional importance. The statistical analysis shows that spring water temperatures correlate well with the mean annual air temperature at the mean catchment elevation. The temperature decrease with increasing elevation corresponds to the air temperature gradient in the Eastern Alps (0.47 °C/100 m). In addition, the springs show a negative correlation of the EC with the mean catchment elevation, which can be explained by a decrease in soil cover and thus reduced CO 2 uptake of the water, as well as dilution by rainwater. This leads to less carbonate dissolution, which is also reflected in less HCO 3 − contents. Corrected for the elevation effect, the investigated dolomite springs, have on average a 2.7% higher EC than limestone springs. A difference was also found between the Hauptdolomit and the Wettersteindolomit rock types, which are widespread in Lower Austria, with the latter displaying higher values on average by 2.2%. This indicates longer residence times of the spring water due to less karstification of the Wettersteindolomit.","PeriodicalId":55415,"journal":{"name":"Austrian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135845239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Georg H. Erharter, Mathias Steinbichler, Markus Eder, Esther Hintersberger, Dominik Jaeger
Abstract Being able to create digital geological maps has become a basic requirement for the skillset of today’s geologists. QGIS is a geographical information system that receives increasing popularity due to its user-friendliness and the fact that it is an open access software. This contribution provides an update and extension to a previously published software guideline that gives a stepwise explanation on how to create a geological map with QGIS. The article serves as a brief overview of the guideline through an illustrated example. The guideline itself is published as a supplement to this paper. Within six sections, the guideline explains how to create a geological map with QGIS: 1. Introduction, 2. Download and installation, 3. Basemaps, 4. Map drawing, 5. Plugins, 6. Layouts. The aim is to instruct geologists who are completely inexperienced with digital map creation as well as provide specific information for more advanced users. In general, providing software guidelines for the geological community is an important step towards increasing geologists’ digital proficiency and to keep up with today’s fast paced developments in digitalization.
{"title":"A new guideline for geological maps with QGIS","authors":"Georg H. Erharter, Mathias Steinbichler, Markus Eder, Esther Hintersberger, Dominik Jaeger","doi":"10.17738/ajes.2023.0008","DOIUrl":"https://doi.org/10.17738/ajes.2023.0008","url":null,"abstract":"Abstract Being able to create digital geological maps has become a basic requirement for the skillset of today’s geologists. QGIS is a geographical information system that receives increasing popularity due to its user-friendliness and the fact that it is an open access software. This contribution provides an update and extension to a previously published software guideline that gives a stepwise explanation on how to create a geological map with QGIS. The article serves as a brief overview of the guideline through an illustrated example. The guideline itself is published as a supplement to this paper. Within six sections, the guideline explains how to create a geological map with QGIS: 1. Introduction, 2. Download and installation, 3. Basemaps, 4. Map drawing, 5. Plugins, 6. Layouts. The aim is to instruct geologists who are completely inexperienced with digital map creation as well as provide specific information for more advanced users. In general, providing software guidelines for the geological community is an important step towards increasing geologists’ digital proficiency and to keep up with today’s fast paced developments in digitalization.","PeriodicalId":55415,"journal":{"name":"Austrian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135009856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Holger Gebhardt, Stjepan Ćorić, Robert Darga, Antonino Briguglio, Bettina Schenk, Winfried Werner, Nils Andersen, Benjamin Sames
The northern Tethyan margin is a key region for determining environmental changes associated with the collision of continental and oceanic tectonic plates and Alpine orogeny. Herein we investigated Middle to Late Eocene neritic to bathyal sediments deposited during an interval of unstable climatic conditions. In order to quantify paleoenvironmental changes, we developed a detailed age model based on biozonations of planktic foraminifera, calcareous nannoplankton, and larger benthic foraminifera. The section at Adelholzen covers the almost complete Lutetian Stage (calcareous nannoplankton zones NP15a-16, planktic foraminifera zones E8-11, shallow benthic (foraminifera) zones SBZ13-15) and large parts of the Priabonian Stage (NP18-20, E14/15), while the intermediate Bartonian Stage (NP17) is completely missing. Foraminiferal, calcareous nannoplankton, and macrofossil assemblages were analyzed for changes in paleo-water depth, mixing and stratification, paleo-primary productivity (pPP), food supply, and bottom water oxygenation. Paleo-water depth estimates range from 50 m (middle neritic, early Lutetian) to nearly 500 m (upper bathyal, late Priabonian). The combination of assemblage composition, planktic and benthic foraminiferal accumulation rates, and derived parameters (carbon-flux to sea floor, pPP) enabled us to identify a series of distinct paleoceanographic events of at least regional significance. Such events are characterized by considerable changes in primary productivity or reduced bottom water ventilation. Calculated pPP-values indicate oligotrophic conditions throughout.
{"title":"Middle to Late Eocene paleoenvironmental changes in a marine transgressive sequence from the northern Tethyan margin (Adelholzen, Germany).","authors":"Holger Gebhardt, Stjepan Ćorić, Robert Darga, Antonino Briguglio, Bettina Schenk, Winfried Werner, Nils Andersen, Benjamin Sames","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The northern Tethyan margin is a key region for determining environmental changes associated with the collision of continental and oceanic tectonic plates and Alpine orogeny. Herein we investigated Middle to Late Eocene neritic to bathyal sediments deposited during an interval of unstable climatic conditions. In order to quantify paleoenvironmental changes, we developed a detailed age model based on biozonations of planktic foraminifera, calcareous nannoplankton, and larger benthic foraminifera. The section at Adelholzen covers the almost complete Lutetian Stage (calcareous nannoplankton zones NP15a-16, planktic foraminifera zones E8-11, shallow benthic (foraminifera) zones SBZ13-15) and large parts of the Priabonian Stage (NP18-20, E14/15), while the intermediate Bartonian Stage (NP17) is completely missing. Foraminiferal, calcareous nannoplankton, and macrofossil assemblages were analyzed for changes in paleo-water depth, mixing and stratification, paleo-primary productivity (pPP), food supply, and bottom water oxygenation. Paleo-water depth estimates range from 50 m (middle neritic, early Lutetian) to nearly 500 m (upper bathyal, late Priabonian). The combination of assemblage composition, planktic and benthic foraminiferal accumulation rates, and derived parameters (carbon-flux to sea floor, pPP) enabled us to identify a series of distinct paleoceanographic events of at least regional significance. Such events are characterized by considerable changes in primary productivity or reduced bottom water ventilation. Calculated pPP-values indicate oligotrophic conditions throughout.</p>","PeriodicalId":55415,"journal":{"name":"Austrian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4558959/pdf/emss-63934.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"33984015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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