新元古代重大地质事件及其与生物演化的耦合关系

Geological Events and Their Biological Responses During the Neoproterozoic Era

新元古代的地球表层系统经历了超大陆裂解与重组、大规模冰期、古海洋氧化、埃迪卡拉生物群辐射与灭绝、后生动物兴起等一系列重大变革,这些地质事件与生物演化在时空上的耦合关系长期受多学科交叉研究领域的广泛关注。Rodinia超大陆的裂解伴随有超级地幔柱活动、古地磁真极移等复杂响应,裂解过程影响了大气圈和水圈中氧气和二氧化碳的循环,并可能直接导致了新元古代极端的气候条件。构造格局的变动对生物的影响主要体现在物质来源和生存环境的改变上,强上升洋流和强地表径流区域的富营养化促使生物大量繁盛。"雪球地球"期间巨大的选择压力为生物的多样化演变提供了可能,而其后冰川的快速消融则促进了生产力的爆发式增长及多种沉积矿产的形成。与此同时,大气—海洋氧气含量的增加和海水化学结构的改变使得多项元素及同位素指标发生了地质历史上最大幅度的波动,这种特殊的地质背景可能最终对生物演化产生了极为深刻的影响。

The Neoproterozoic Era witnessed a series of geological and biological events which may have significantly changed the Earth＇s surface environment. These events are suspected to be linked and their temporal relationships have long been a focus of multidisciplinary studies. Superplume activity and true polar wander through the early Neoproterozoic led to the break-up of Rodinia supercontinent. Indeed,such a large perturbation of deep mantle dynamics exerted a crucial impact on the global cycles of O_2 and CO_2,thus further inducing the extraordinarily dramatic climate.Biological consequences of tectonic re-configuration are mainly reflected in nutrient availability and living conditions.The elevated upwelling and surface runoff could sustain persistent blooms of marine organisms. A Snowball Earth hypothesis has been proposed to explain the tropical glaciation. During times of widespread ice,there must be an intense environmental filter on the evolution of early life. Moreover,the subsequent rapid melting of glaciers may result in the explosion of productivity as well as the formation of major sedimentary minerals. Besides these geological and biological events,this period is also characterized by prominent fluctuations of geochemical proxies,which indicate great changes of atmosphere and ocean at this critical interval.