古新世-始新世极热事件研究进展  

A REVIEW ON THE PALEOCENE-EOCENE THERMAL MAXIMUM

作　　者：陈祚伶[1,2] 丁仲礼[1] 

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]中国科学院研究生院,北京100049

出　　处：《第四纪研究》2011年第6期937-950,共14页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:40730208)资助

摘　　要：古新世-始新世极热事件(PETM事件)是发生在早新生代的一次极端碳循环扰动和全球变暖事件,主要表现为大气CO_2浓度快速增加和全球增温。研究显示该时期全球地表温度增加了5～6℃,高低纬度间温度梯度减小,同时伴随有水循环加快及大规模生物灭绝、演替和迁徙现象。据估算,PETM时期从地层释放到表生系统的CO_2总量同预期人类过去与未来燃烧化石燃料所产生的总量可资对比,因此国际学术界将其视作预估今后可能发生的增温效应、环境效应和生态效应的重要基础。本文根据最新研究成果,对该事件的触发机制、碳排放量、气候及生态效应等方面作一综述。The Paleocene-Eocene Thermal Maximum （PETM）is an extreme carbon perturbation and global warming event,which was superimposed on the long-term Early Cenozoic warming trend. The PETM is characterized by an abrupt and large negative excursion （ - 2‰ - - 6‰） of carbon isotope compositions of marine and terrestrial sedimentary materials. Paleotemperature proxies suggest an increase in global surface temperature of approximately 5 -6% ,and a coincident decrease in temperature gradient between high-latitudes and low-latitudes. This event is correlative with a global accelerated hydrological cycle and large-scale biotic turnover and vertebrate mammalian migrations. Based on carbon isotope records and computer simulations, the amount of carbon totally released to the exogenic carbon cycle system is estimated to be comparable with the anticipative carbon amount that would be released to the atmosphere by burns of fossil fuels. Therefore, a comprehensive study of this event is potentially helpful to the projection of the environmental and ecological impacts induced by human activity in the future. In this paper, we overviewed the recent progresses of studies on the event, particularly focusing on the triggering mechanisms, estimation of released total carbon, and the climatic and ecological impacts. Of all mechanisms put forward, large-scale dissociation of methane hydrate is the reliable hypothesis. It is likely that increased temperature before PETM event led to hydrate instability and thus to an enhanced emission of methane, imposing a strong positive feedback that would made dissociation of more methane hydrate along continental slope, and then caused the PETM event. Because of pervasive dissolution of deep sea sedimentary carbonate and severe acidification of ocean, the real magnitude of carbon isotope excursion may be embodied in terrestrial carbon isotope records （ ca. -6%o） rather than the ocean archives （ ca. -2.5‰）. The -6‰ of CIE （ carbon isotope excursion）indicates a release of appro

关 键 词：PETM 碳循环 CIE 气候效应 生态效应 

分 类 号：P534.61[天文地球—古生物学与地层学] P597.3[天文地球—地质学]