古新世—始新世最热事件对地球表层循环的影响及其触发机制  

The Impacts of the Paleocene-Eocene Thermal Maximum(PETM) Event on Earth Surface Cycles and Its Trigger Mechanism

作　　者：赵玉龙[1] 刘志飞[1] 

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092

出　　处：《地球科学进展》2007年第4期341-349,共9页Advances in Earth Science

基　　金：教育部新世纪优秀人才支持计划"早新生代极端气候事件的海陆对比研究";国家自然科学基金项目"南海中更新世气候转型期千年尺度气候波动及其全球意义"(编号:40331002);"西太平洋暖池与东亚古环境:沉积记录的海陆对比"(编号:40321603);霍英东教育基金会项目"青藏高原东部晚第四纪侵蚀和气候演变在南海中的记录"(编号:101018)资助

摘　　要：古新世—始新世最热事件(PETM,Paleocene-Eocene Thermal Maximum)是发生在古新世—始新世交界时的一次全球性的气候突变事件。它造成了大洋环流模式的突然倒转和海水盐度、大气湿度的迅速上升。海洋表层生态系统和陆地生态系统生产力迅速上升,许多属种的植物、动物、微生物生活范围向高纬区扩大;大洋底栖微生物发生集群灭绝。现代哺乳动物的主要属种(灵长类、奇蹄类及偶蹄类)产生,哺乳动物演化进程发生重大改变。地球表层碳循环系统发生不同程度的碳同位素负偏移,全球碳循环系统发生大规模搅动。对于PETM的触发机制,主流的观点认为是海底天然气水合物突然释放造成巨量甲烷迅速进入表层系统引发的碳循环系统内部反馈。而对于甲烷释放的原因,又存在着减压释放和热释放两种解释;此外还有科学家用岩浆作用和地外星体撞击来解释PETM的发生。The Paleocene-Eocene Thermal Maximum （PETM） event is an abrupt climate change event that occurred at the Paleocene-Eocene boundary. The event led to a sudden reversal in ocean overturning along with an abrupt rise in sea surface salinity （SSSs） and atmospheric humidity. An unusual proliferation of biodiversity and productivity during the PETM is indicative of massive fertility increasing in both oceanic and terrestrial ecosystems. Global warming enabled the dispersal of low-latitude populations into mid-and high-latitude. Biological evolution also exhibited a dramatic pulse of change, including the first appearance of many important groups of ＂modern＂ mammals （such as primates, artiodactyls, and perissodactyls） and the mass extinction of benthic foraminifera. Massive input of 12C enriched carbon into the oceanic-atmospheric system induced a prominent negative carbon isotope excursion （CIE） and rapid perturbation of global carbon cycle. The trigger mechanism of PETM remains obscure. One plausible explanation involves abrupt release of marine methane hydrate. Magma activity and bolide effect are also announced accounting for the occurrence of PETM. As for the gas hydrate hypothesis, there are still a lot of different theories explaining how the thermal or depressure dissociation of gas hydrate happened.

关 键 词：PETM事件 大洋环流模式倒转 哺乳动物演化 碳同位素负偏移 甲烷释放 

分 类 号：P71[天文地球—海洋科学]