Carbon cycle and sea-water palaeotemperature evolution at the Middle-Late Jurassic transition, eastern Paris Basin (France)

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• 作者：Pierre Pellenard^a ; ^{Pierre.Pellenard@u-bourgogne.fr" class="auth_mail} ; Romain Tramoy^a ; ^b ; Emmanuelle Puc&eacute ; at^a ; Emilia Huret^c ; Mathieu Martinez^a ; Ludovic Bruneau^a ; Jacques Thierry^d
• 关键词：Carbon isotopes ; Oxygen isotopes ; Sea-water paleotemperatures ; Paleoenvironmental changes ; Callovian ; Oxfordian
• 刊名：Marine and Petroleum Geology
• 出版年：May, 2014
• 年：2014
• 卷：53
• 期：Complete
• 页码：30-43
• 全文大小：4791 K

文摘

A very high-resolution carbon and oxygen stable isotope analysis (bulk-carbonate) of a biostratigraphically well-constrained Callovian-Oxfordian series is provided here for the first time. The homogeneity of the clayey series and the weak diagenetic alteration allow the isotopic signal variations to be considered as primary in origin. A prominent and brief negative excursion in the 未¹³C curve (鈭?鈥?, occurring at the start of the Middle Callovian (Jason Zone - Obductum Subzone) and correlated regionally, suggests a possible methane release. The increasing 未¹³C values thereafter up to the Early Oxfordian, concomitant with a warming episode, highlight the burial of carbon in organic-rich layers which, in return, may have triggered a decrease in atmospheric pCO₂. At higher frequencies, observed fluctuations of the 未¹³C and 未¹⁸O values are orbitally driven (405-kyr and 100-kyr eccentricity cycles) and may correspond to the salinity and temperature variability recorded in sea water. The 未¹⁸O isotopic measurements from well-preserved diagenetically screened belemnites and bivalves along the series, compared to available data from Tethyan domains, agree with the scenario of a global cooling at the Middle-Late Jurassic transition. The well-dated 未¹⁸O isotopic curve suggests that the onset of this cooling event occurred at the end of the Coronatum Zone (Middle Callovian).