Sedimentary Expressions of the Early Jurassic Jenkyns Event in an Inland Lacustrine System in the Yin'gen-Ejinaqi Basin,North China  

作　　者：YANG Bing XU Guozhen HUI Guangji WEI Yi ZHANG Xinzhi YI Jinjun SUN Siyuan ZHANG Sujiang 

机构地区：[1]Cores and Samples Center of Natural Resources,Langfang,Hebei 065201,China [2]Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences,Nanjing 210008,China [3]North China Institute of Science and Technology,Langfang,Hebei 065201,China

出　　处：《Acta Geologica Sinica(English Edition)》2024年第5期1359-1375,共17页地质学报（英文版）

基　　金：financially supported by China Geological Survey Project(DD20230138;DD20242504);The National Natural Science Foundation of China(Grant Numbers 41702366);The Sinopec Project(34550000-21FW2099-0055)。

摘　　要：The Jenkyns Event,more widely known as the Toarcian Oceanic Anoxic Event(T-OAE),is marked by globally distributed negative carbon-isotope excursions,widespread oxygen depletion,and large-scale organic carbon burial,which indicate major climate/environmental perturbations in Earth's surface systems during the Early Jurassic.Although extensive research has been conducted in European continental settings,particularly in the western peri-Tethys regions,the impacts of this event beyond Europe remains largely unexplored.Here,a multiapproach study including investigations into the sporepollen assemblages,pyrite framboids,clay minerals,total organic carbon(TOC)levels,and organic carbon isotope(δ13Corg)levels in a lacustrine borehole section(MED1)from the Yin'gen-Ejinaqi Basin,North China,provides evidence of the occurrence of the Jenkyns Event and its extensive sedimentary responses in the eastern Tethys terrestrial systems.Two distinct spore-pollen assemblages have been identified in MED1(drilling depth:982.4 m to 1267.5 m),with the Cycadopites-Protopinus-Osmundacidites assemblage in the lower part(1267.5 m to 1132.9 m)indicating a middle Early Jurassic age and the Classopollis assemblage in the upper part(1132.9 m to 985.7 m)suggesting a Toarcian age.Framboidal pyrite data suggest more anoxic conditions during the deposition of black mudstone and shale intercalations in the lower part of the Classopollis assemblage(1132.9 m to 1066.9 m),which combined with organic carbon enrichment and negativeδ13Corg excursions,are considered the paleoenvironmental response to the Jenkyns Event in the study area.Furthermore,the evolution of vegetation groups changed from plant groups characterized by bisaccate and cycad pollen,as well as fern spores,to vegetation groups represented by Cheirolepidiaceae pollen across the Jenkyns Event,as evidenced by sporepollen data,together with the clay mineral assemblage change characterized by a notable increase in illite at the expense of kaolinite,suggests that while a subtropical-temperate cl

关 键 词：spore-pollen assemblages clay minerals pyrite framboids organic carbon isotope Jenkyns event 

分 类 号：P512.2[天文地球—地质学] P534.52