寒武纪早中期(约542–505 Ma)是地质历史上著名的转折时期，见证了后生动物在较短时间内快速辐射以及地球表层环境的巨大变化。前人研究认为海洋氧化程度的提高为后生动物演化提供了环境基础，但最新研究显示该时期海洋氧化还原状态并不稳定，在较短时间内可能呈现明显波动状态，且存在空间不均一性，而对造成这种特殊海洋环境的驱动因素，如大陆风化、海洋营养物质循环、初级生产力变化等的研究较为薄弱，对这些方面所知甚少，而这些方面的信息，对理解海洋环境的变化非常重要。本申请拟以海相碎屑沉积岩为研究对象，系统分析能够反映硅酸盐化学风化强度的锂(Li)同位素和能够示踪大陆风化物质来源的钕(Nd)同位素等指标，反演寒武纪早中期全球大陆风化及物源输入随时间的演化趋势，并揭示其与海洋氧化还原状态变化的关系，为探索早期动物和环境协同演化提供新的线索。

It is a critical interval from the early to the middle Cambrian (ca. 542–505 Ma), which witnessed the rapidradiation of the Metazoans and the large changes in Earth’s surface environment. The evolution of metazoans has been commonly attributed to the global oceanic oxygenation. However, recent studies suggested that the redox state of Precambrian-Cambrian ocean was not under a steady state, instead, characterized by large fluctuations of marine environment and spatiotemporal heterogeneity. Further, the environmental factors controlling the marine redox variations during this period, such as continental weathering, marine nutrient cycling, primary productivity, are not well constrained, but play an important role of unraveling the evolution of Earth’s surface environment. This project plans to concentrate on Li-isotope compositions and Nd-isotope compositions of the siliciclastic successions of the above stated periods, which can be used to well constrain the secular changes in silicate chemical weathering intensity and the sources of terrestrial materials. Based on these analyses, we aim to track the long-term evolution of chemical weathering and terrestrial inputs from the early Cambrian to the middle Cambrian, and to provide more insights into the role of continental weathering on evolution of marine redox states and early animals.