Abstract: A shark-tooth apatite δ 18 O record of the early Palaeogene North Sea reflects changes in regional hydrography by showing variable temperatures and salinities. A 2–4 Ma period in the early Eocene was particularly influenced by substantial surface-water freshening, indicated by a 3–4‰ reduction of δ 18 O values. The magnitude of the δ 18 O decrease indicates a depletion in 18 O of surface waters by 2–3‰ relative to Eocene mean ocean water. This value is lower than that of coeval lakes reconstructed from freshwater gastropod δ 18 O values from the Paris Basin, suggesting that large rivers with high-latitude catchment areas drained into the North Sea. The period of surface-water freshening began close to the Palaeocene – Eocene thermal maximum, when relative sea-level fall, tectonic uplift and basaltic volcanism caused a temporary isolation of the North Sea. North Atlantic and North Sea surface waters became reconnected during a series of early Eocene transgressions.
Middle to Late Ordovician carbonates were collected in South China (Anhui Province) from the Kuniutan, Datianba, and Pagoda formations in the Dingxiang and Daling sections and analysed for high‐resolution carbon isotope chemostratigraphy. An increase by 0.4‰ in δ 13 C carb is observed in the upper part of the Kuniutan Formation ( Eoplacognathus pseudoplanus Biozone), representing the rising limb of the Middle Darriwilian Isotopic Carbon Excursion (MDICE). In the upper part of the Datianba Formation, positive shifts of ca. 1‰ are recorded in the studied section which compare with the carbon shifts reported in North America and Baltoscandia. A pronounced positive δ 13 C carb excursion of ca. 1.5‰ from the lower part of the Pagoda Formation can be correlated with the global Guttenberg Isotopic Carbon Excursion (GICE). The documentation of three carbon isotope shifts in this study provides new evidence for changes in the global carbon cycle from Darriwilian to Early Katian which could have been influenced by changes in global climate and primary productivity.
Research Article| September 01, 1999 Hydrothermal origin of Devonian conical mounds (kess-kess) of Hamar Lakhdad Ridge, Anti-Atlas, Morocco: Comment and Reply Michael M. Joachimski; Michael M. Joachimski 1Institute of Geology, University of Erlangen, Schlossgarten 5, 91054 Erlangen, Germany; joachimski@geol.uni-erlangen.de. Search for other works by this author on: GSW Google Scholar Werner Buggisch; Werner Buggisch 2Institute of Geology, University of Erlangen, Schlossgarten 5, 91054 Erlangen, Germany Search for other works by this author on: GSW Google Scholar Driss Mounji; Driss Mounji 3Département de géologie et de génie géologique, Université Laval, Québec G1K 7P4, Canada Search for other works by this author on: GSW Google Scholar P.-A. Bourque; P.-A. Bourque 5Département de géologie et de génie géologique, Université Laval, Québec G1K 7P4, Canada; bourque@ggl.ulaval.ca Search for other works by this author on: GSW Google Scholar M. M. Savard M. M. Savard 4Delta-lab, Geological Survey of Canada, Centre géoscientifique de Québec, Ste-Foy, Québec G1V 4C7, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Michael M. Joachimski 1Institute of Geology, University of Erlangen, Schlossgarten 5, 91054 Erlangen, Germany; joachimski@geol.uni-erlangen.de. Werner Buggisch 2Institute of Geology, University of Erlangen, Schlossgarten 5, 91054 Erlangen, Germany Driss Mounji 3Département de géologie et de génie géologique, Université Laval, Québec G1K 7P4, Canada P.-A. Bourque 5Département de géologie et de génie géologique, Université Laval, Québec G1K 7P4, Canada; bourque@ggl.ulaval.ca M. M. Savard 4Delta-lab, Geological Survey of Canada, Centre géoscientifique de Québec, Ste-Foy, Québec G1V 4C7, Canada Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1999) 27 (9): 863–864. https://doi.org/10.1130/0091-7613(1999)027<0863:HOODCM>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Michael M. Joachimski, Werner Buggisch, Driss Mounji, P.-A. Bourque, M. M. Savard; Hydrothermal origin of Devonian conical mounds (kess-kess) of Hamar Lakhdad Ridge, Anti-Atlas, Morocco: Comment and Reply. Geology 1999;; 27 (9): 863–864. doi: https://doi.org/10.1130/0091-7613(1999)027<0863:HOODCM>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract No Abstract Available. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
ABSTRACT We present sequential oxygen isotope records (δ 18 O phosphate vs. VSMOW) of horse tooth enamel phosphate of six individuals from two adjacent Palaeolithic sites in Lower Austria. Three molars from the site Krems‐Wachtberg date to 33–31k cal a bp , and three molars from Kammern‐Grubgraben to 24–20k cal a bp. All teeth show seasonal isotope variations, which are used to reconstruct the annual oxygen isotope composition of drinking water (δ 18 O dw ) and palaeotemperatures. Measured δ 18 O phosphate values ranged from 8.6 to 13.0‰ and from 10.8 to 13.9‰ at Krems‐Wachtberg and Kammern‐Grubgraben, respectively. An inverse modelling approach was used to reconstruct summer and winter temperatures after a correction for glacial oceanic source water δ 18 O. Reconstructed annual δ 18 O dw was −16.4 ± 1.5‰ at Krems‐Wachtberg and −15.3 ± 1.4‰ at Kammern‐Grubgraben, resulting in annual temperatures of −5.7 ± 3.1 and −3.5 ± 2.9°C, respectively. Summer and winter temperatures reconstructed from individual teeth exhibit high seasonal variations with moderate summer temperatures and extremely low winter temperatures typical for a polar tundra climate. Isotopic differences between individuals are attributed to interannual climate variability or to different drinking water sources. Our reconstructed temperatures are, overall, consistent with previously reported values from European horse teeth, when taking regional differences into account.
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