华南黔桂地区石炭纪中期冰期事件的沉积与地球化学记录

The mid-Carboniferous (Visean–Moscovian) glaciation events in the Gondwanan land dramatically influenced the global climate, paleoceanography, and paleoecology. Most of the integrated sedimentological and geochemical studies were carried out for the Euramerica block. The South China block was located in the eastern Paleotethys Ocean near the paleoequator during mid-Carboniferous, which is critical to a better understanding of these glaciation events. This project focuses on platform-to-slope sedimentary successions in the Guizhou and Guangxi regions, South China, and includes the following objectives: (1) identify sedimentary cycles (cyclothems) in carbonate slope successions based on systematic sedimentology, sedimentary petrography, and sequence stratigraphy, and make correlation with carbonate platforms of the same region and the globe; (2) explore the positive carbon isotope excursion across the mid-Carboniferous boundary in the eastern Paleotethys Ocean; (3) reveal the paleoenvironmental conditions for the mid-Carboniferous extinction event based on integrated studies on organic carbon and nitrogen isotopes, and carbonate carbon isotopes; (4) establish global mid-Carboniferous seawater strontium isotope curve based on conodont apatite, and decipher its implications on paleoclimate and tectonics. This integrated, multi-disciplinary project will eventually make a critical contribution to a better understanding of the paleoclimate, sea-level change, paleoceanography, and biotic evolution during the late Paleozoic ice age, and provide geological evidence and projections into the current and future global climate change.

石炭纪中期（Visean–Moscovian）在冈瓦纳大陆发生了一系列冰川事件，极大的影响了当时的古海洋、古气候和古生态。综合沉积与地化研究主要集中在欧美大陆，我国华南板块石炭纪中期位于古特提斯洋东部，是研究该冰期事件的重要地块。本项目以华南黔桂地区石炭系中部不同相区的典型剖面为主要研究对象，通过系统研究沉积学、沉积岩石学和层序地层学，识别斜坡相的沉积旋回；通过高精度碳酸盐岩碳、氧同位素研究，探讨全球石炭纪中期碳循环异常事件在古特提斯洋东部海域的响应；通过选择关键层段开展有机碳、氮同位素研究，揭示当时的海洋循环和初级生产率状况，探讨石炭纪中间界线生物事件的古环境背景；开展高精度牙形刺锶同位素研究，建立可供全球地层对比的石炭纪中期海水的锶同位素曲线，并探讨其与古气候和古构造的关系。为正确理解晚古生代大冰期的古气候变迁、海平面变化、古海洋循环及生物更替特征等科学前沿做出我国的重要贡献。

石炭纪中期在冈瓦纳大陆发生了一系列冰川事件，极大的影响了当时的古海洋、古气候和古生态。综合沉积与地化研究主要集中在欧美大陆，我国华南板块石炭纪中期位于古特提斯洋东部，是研究该冰期事件的重要地块。本项目以华南黔桂地区石炭系中部不同相区的典型剖面为主要研究对象，通过系统研究沉积学、沉积岩石学和层序地层学，识别沉积旋回，揭示相对海平面变化规律，表明低纬度地区的沉积旋回受冰川性全球海平面变化及冈瓦纳冰川事件控制；通过高精度碳酸盐岩碳、氧同位素研究，探讨全球石炭纪中期碳循环异常事件在古特提斯洋东部海域的响应，发现在石炭系中间界线并不存在之前基于欧美地区报道的明显正漂事件；通过对石炭系中间界线开展有机碳、氮、铀同位素研究，揭示石炭纪中间界线生物事件是由全球冰川性海平面及氧化还原环境的波动引起的；高精度牙形刺锶同位素研究，建立可供全球地层对比的石炭纪中期海水的锶同位素曲线，首次提出大冰期的最高峰是在大陆风化整体下降及热带雨林植被更替的背景下，有机碳埋藏由大陆转向海洋所导致。为正确理解晚古生代大冰期的古气候变迁、海平面变化、古海洋循环及生物更替特征等科学前沿做出我国的重要贡献。