早侏罗世大洋缺氧事件在塔里木盆地的响应  

Responses to the Early Jurassic Oceanic Anoxic Events in the Tarim Basin

作　　者：邱若原 方琳浩 卢远征[5] 邓胜徽[5] 张新智 吕沛宗 任嘉豪 黄汝婷 房亚男 张小宇 李宏佳 鲜本忠[3,4] 师生宝[3,4] QIU RuoYuan;FANG LinHao;LU YuanZheng;DENG ShengHui;ZHANG XinZhi;LÜPeiZong;REN JiaHao;HUANG RuTing;FANG YaNan;ZHANG XiaoYu;LI HongJia;XIAN BenZhong;SHI ShengBao(Key Laboratory of Cenozoic Geology and Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;University of Chinese Academy of Sciences,Beijing 100049,China;College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;State Key Laboratory of Petroleum Resource and Prospecting,China University of Petroleum(Beijing),Beijing 102249,China;Research Institute of Petroleum Exploration and Development,PetroChina,Beijing 100083,China;Nanjing Institute of Geology and Paleontology,Chinese Academy of Sciences,Nanjing 210008,China)

机构地区：[1]中国科学院地质与地球物理研究所新生代地质与环境重点实验室,北京100029 [2]中国科学院大学,北京100049 [3]中国石油大学(北京)地球科学学院,北京102249 [4]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [5]中国石油天然气股份有限公司勘探开发研究院,北京100083 [6]中国科学院南京地质古生物研究所,南京210008

出　　处：《沉积学报》2023年第2期425-434,共10页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(41502024);中国石油大学(北京)青年拔尖人才项目(2462014YJRC027)。

摘　　要：早侏罗世Toarcian期大洋缺氧事件(简称“T-OAE”),被认为与Karoo-Ferrar大火成岩省爆发以及与甲烷气水合物有关的温室气体迅速释放导致全球变暖密切相关。该事件在特提斯洋区有较详细研究,但在陆相生态系统中的环境变化和沉积响应报道较少。本文报道了塔里木盆地北缘库车河地区的有机碳同位素地层数据,“东剖面”和“西剖面”中δ13C曲线总体的正偏移趋势被多幕次地快速负偏移打断,表明地表碳循环受到了巨大扰动。事件层内δ13C值的突然负向波动暗示了大气碳库在短时间内有相对轻同位素特征的碳注入,并呈现不稳定的、阶段性注入的特点,推测可能与增温引发的正反馈有关。沉积相突变与孢粉种类的衰减表明该区沉积环境发生了巨大变化;碎屑白云岩和紫红色泥岩的出现和湿生孢粉的衰减以及中生孢粉的出现,均表明在T-OAE期间塔里木盆地北缘气候转为干热。该研究报道了首个来自陆相沉积盆地边缘的T-OAE记录,对于深入理解二氧化碳浓度显著升高背景下引起的陆地系统响应具有借鉴意义。The Early Jurassic Toarcian Oceanic Anoxic Event(T-OAE)is believed to be closely related to the Karoo-Ferrar igneous explosion and the global warming caused by the rapid release of greenhouse gases related to methane gas hydrates.This event has been studied in detail in the Tethys Ocean region,but the environmental changes and sedimentary responses in terrestrial ecosystems have received less attention.Here,the organic carbon isotopic strati⁃graphic data for the Kuqa River area at the northern margin of the Tarim Basin are reported.The overall positive ex⁃cursion trend ofδ13C curves in the East and West sections are interrupted by multi-stage rapid negative excursions,which indicates that the surface carbon cycle has been greatly disturbed.The rapid fluctuation of theδ13C value in the event layer suggests that the carbon source with light isotopic characteristics was injected into the atmospheric carbon pool over a short period of time,and was characterized by unstable and periodic injection.It is speculated that this may be related to the positive feedback caused by warming.The abrupt change in sedimentary facies and the decrease in sporopollenin species indicate that the sedimentary environment has changed greatly.The presence of clastic dolo⁃mite and purplish mudstone,the attenuation of wet palynology and the occurrence of mesopalynology all indicate that the climate at the northern margin of Tarim Basin became dry and hot during T-OAE.This study reports the first TOAE record from the margin of a continental sedimentary basin,and is crucial to understanding the evolution of ter⁃restrial systems in the context of the significant increase of carbon dioxide in the present period of Earth history.

关 键 词：早侏罗世 塔里木盆地 大洋缺氧 碳同位素负偏 气候变化 

分 类 号：P532[天文地球—古生物学与地层学]