新元古代成冰纪雪球地球与化学风化作用  

Chemical Weathering during the Neoproterozoic Snowball Earth Events

作　　者：陈欣阳 李彪 李超[1,2,3] Chen Xinyang;Li Biao;Li Chao(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China;Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China;International Center for Sedimentary Geochemistry and Biogeochemistry Research,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]成都理工大学油气藏地质及开发工程全国重点实验室,四川成都610059 [2]成都理工大学沉积地质研究院,四川成都610059 [3]成都理工大学沉积与生物地球化学国际研究中心,四川成都610059

出　　处：《地球科学》2025年第3期1048-1065,共18页Earth Science

基　　金：国家重点研发计划项目(No.2022YFF0800100);国家自然科学基金项目(Nos.42425002,42373070,42130208).

摘　　要：新元古代成冰纪(约720~635 Ma)发生了两次全球范围的雪球地球事件(斯图特冰期和马里诺冰期),是地球生命系统和环境演化的重要转折期.越来越多的证据显示雪球地球时期的气候和海洋氧化还原状态存在显著的时空波动,然而这一特征背后的碳循环-海陆系统交互以及冰期气候波动的驱动机制还很不清楚.作为链接雪球地球发育、海洋化学和生物演化最为关键过程之一的大陆风化作用目前仍旧没有被有效刻画是其中的一个重要原因.本文综述了现有风化指标及其在成冰纪化学风化强度方面的研究现状,在此基础上,统计了全球28个成冰纪剖面(含钻孔)867件碎屑岩样品的主量元素数据,利用ln(Al_(2)O_(3)/Na_(2)O)这一高效风化指标定量重建了从拉伸纪晚期到埃迪卡拉纪早期全球平均化学风化强度的演化趋势,发现了多次化学风化的强弱波动,表明冰期的启动和结束均与化学风化作用息息相关.此外,马里诺冰期的平均风化强度显著高于斯图特冰期,可能暗示马里诺冰期存在一定程度的水循环.未来的研究应进一步推动多指标的综合应用,以加深对成冰纪化学风化机制的理解,为全球环境演化的探索提供更多深入的视角和证据支持.Two global-scale Snowball Earth events occurred during the Cryogenian period of the Neoproterozoic era(ca.720-635 Ma),representing a crucial transition period for the Earth’s biological systems and environmental evolution.An increasing amount of evidence indicates that there are spatio-temporal fluctuations in the climate and marine redox state during the Snowball glaciation.However,the driving mechanisms of the carbon cycle-land-ocean system interaction and glacial climate fluctuations during this period remain largely unclear.Continental weathering is a key process linking snowball development,ocean chemistry,and biological evolution,but existing research has been unable to effectively characterize continental weathering during the Snowball period.This paper summarizes the current status of proxies for chemical weathering intensity during the Cryogenian period,and statistically analyzes the major-element data of 867 clastic rock samples from 28 Cryogenian sections(including drill cores)worldwide.Using the index of ln(Al_(2)O_(3)/Na_(2)O),the evolutionary trend of the global average chemical weathering intensity from the Late Tonian period to the Early Ediacaran period is quantitatively reconstructed.Three fluctuations in chemical weathering intensity are discovered,indicating that the onset and termination of glaciation are closely related to chemical weathering.In addition,the average weathering intensity during the Marinoan glaciation is significantly higher than that during the Sturtian glaciation,possibly suggesting the existence of a certain degree of hydrological circulation during the Marinoan glaciation.Future research can further apply the comprehensive application of multiple proxies to deepen the understanding of the chemical weathering mechanisms during the Cryogenian period,and provide more in-depth perspectives and evidence to support the exploration of global environmental evolution.

关 键 词：新元古代 成冰纪 化学风化指标 雪球地球 碳循环 气候变化 

分 类 号：P532[天文地球—古生物学与地层学]