通过对贵州瓮安合磷岩系剖面进行碳同位素分析,对震旦纪陡山沱期的成磷事件、生物事件及古海洋环境的变化进行了研究.瓮安大塘剖面陡山沱组碳酸盐岩碳同位素值表现为正偏移的趋势,与其他地区同期碳同位素变化趋势相似.这与大冰期后生物生产率的提高有关,其中的负偏移与环境的波动相关,环境的快速变化刺激了生物的进化.穿岩洞剖面上磷矿段的黑色碳质磷块岩获得的较低的有机碳同位素值与浮游生物吸收12C有关,体现了生物有机质聚磷作用.该时期的碳酸盐岩碳同位素值的正偏移、磷矿的沉积与生物事件之间有一定的关联性,大洋深部的缺氧事件使底水富磷质;随着古海洋流通性的提高,富磷海水随上升洋流运移到浅海沉积成矿,并为生物圈供应营养物质,进而引发生物竞争及推动进化.%By analysing the carbon isotope in the phosphatic series section in Weng'an, this paper studies the phosphorite-forming events, biological events and changes of the ancient ocean evolution in the Sinian Doushantuo period. It finds that the δ13Ccarb value shows a trend of positive excursion in the Doushantuo Formation of the Datang section of Weng'an. The trend of δ13 Ccrf, in other places around the world indicates I similar pattern. This is related to the elevated biological productivity after the great ice age. The negative excursion is related to the fluctuations in the environment. Rapid changes in the environment stimulate the evolution of living beings. The value of δ13 Corg of the black carbonaceous phosphorite in the Doushantuo Formation of the upper phosphoric mine sector of the Chuanyandong section is very low. Because the accumulation of 12C is absorbed by plankton, the organic matte1 play an important part in the formation of phosphorite. The δ13 Ccarb value's positive excursion and deposition of phosphorite and biological events had some relevance. The oceanic anoxic events cause; the bottom water to be rich in phosphorus. With the improvement of the ancient ocean circulatior, the bottom water with rich phosphorus is migrated to the shallow water by the upwelling current and deposited into the phosphate, which can supply nutrients for the biosphere. Then, it leads to the I jmpetition and evolution of living beings in the biosphere.
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