论文部分内容阅读
新元古代-寒武纪和二叠-三叠纪转折时期由于分别发生了最为壮观的生物辐射事件(寒武纪生物大爆发)和最具灾难性的生物灭绝事件(二叠纪末生物大灭绝),被认为是地球生命演化史中两个最为关键的转折时段.然而,最新的一些研究表明新元古代-寒武纪和二叠-三叠纪转折时期的地质与生物演化历史具有一定的相似性,许多新元古代-寒武纪之交发生的重大生物与地质事件在古生代-中生代之交重复发生,这些事件包括与地球深部地幔柱活动有关的地表大陆重组、大规模冰川的形成和消融、与地表和大气环境变化密切相关的C,Sr,S同位素波动、碳酸盐岩的异常沉积以及生物的多次辐射和大规模灭绝等.这些事件的重复发生表明地球深部活动是地表环境发生急剧变化的主要动因,而地表环境的改变导致生物多样性发生剧变.进一步深入比较表明,这两个转折时期虽然发生重复性的重大生物、地质和地球化学异常事件,但具体型式、幅度和过程有明显差别.新元古代的Rodinia大陆在雪球事件以前就已经开始解体,而石炭纪至二叠纪的Pangea大陆在大冰期以后才开始裂解.生物更替的水平比较表明新元古代-寒武纪之交主要反映在埃迪卡拉生物群的集群灭绝和大量新的生物门类占领新的生态空间,是一级新的生态系统的形成过程;而二叠纪末生物大灭绝虽然造成大量生物灭绝、造礁作用和成煤作用停止,但主要反映在纲和目一级生物类群的灭绝与新生,大灭绝后,残存的生物在早三叠世晚期开始重新占领生态空间,复苏时间也远远短于寒武纪早期的小壳动物发展阶段,是一种生态系统结构组成的重大变化.与生物大规模更替相伴生的两个关键转折时期的碳同位素等均发生了强烈波动,但波动的幅度和频率有所不同,说明当时的大气和海水介质条件和地质背景均存在明显差别.超级联合古陆、大规模的冰期形成和消融、C,Sr和S等同位素的强烈波动以及生物多次大灭绝和辐射等重复发生在新元古代-寒武纪与二叠-三叠纪转折时期给我们带来了新的思考,从地球系统整体观出发,开展从地球深部到地表过程的交叉合作研究对认识地球系统各个圈层的相互作用具有重要意义.
The Neoproterozoic-Cambrian and Permian-Triassic transitional periods were characterized by the most spectacular bioradiation events (Cambrian explosion) and the most catastrophic bio-extinction events Extinction) is considered to be the two most crucial transitional periods in the evolution of Earth’s life.However, some recent studies show that the history of geology and biology evolution during the Neoproterozoic-Cambrian and Permian-Triassic transitional periods has certain , Many of the major biotic and geologic events that occurred at the turn of the Neoproterozoic-Cambrian period occurred repeatedly during the Paleozoic-Mesozoic era. These events included the continental reorganization of the surface associated with deep mantle plumes on the Earth, the formation and ablation of large-scale glaciers , C, Sr, S isotope fluctuations closely related to the surface and atmospheric environment changes, the abnormal sedimentation of carbonate rocks and biological multiple radiation and mass extinction, etc. The recurrence of these events indicates that deep earth activities are the occurrence of the surface environment The main reason for the rapid change, and changes in the surface environment led to drastic changes in biodiversity.Further more in-depth comparison shows that although the two turning points during the transition Reproductive major biological, geological and geochemical anomalies, but the specific type, amplitude and process are significantly different.The Neoproterozoic Rodinia mainland snowball event before it began to disintegrate, and the Carboniferous to Permian Pangea The continent began to crack after the Great Ice Age.The level of biological turnover shows that the Neoproterozoic-Cambrian cross was mainly reflected in the extinction of the cluster in Edicala and the large number of new biological species occupying the new ecological space, Although the end-Permian mass extinction caused a large number of extinctions, reef-building and coal-formation stopped, it was mainly reflected in the extinction and rejuvenation of the biological groups at the level and the target level. After the mass extinction, the remnant Of organisms began to re-occupy the ecological space in the late Triassic, the recovery time is much shorter than that of the early stage of the Cambrian development of the Cambrian, which is a major change in the composition of the ecosystem structure. Of the two key turning points of carbon isotopes and so have undergone strong fluctuations, but the volatility of the magnitude and frequency are different, indicating the atmosphere and the sea at the media There are significant differences in the geological conditions and the geological conditions.Colonial association with ancient continent, large-scale glacial formation and ablation, strong fluctuations of C, Sr and S isotopes, and repeated mass extinction and radiation of organisms occur repeatedly in the Neoproterozoic- The Wuji and Permian-Triassic transitional periods brought us new thinking. Starting from the perspective of global system as a whole, the study of cross-cooperation from deep into the surface of the earth is of great importance to the understanding of the interaction between the various layers of the Earth system significance.