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伊迪卡拉纪以地史上最突出的同位素负异常和重大的生物演化为重要特征.迄今华南伊迪卡拉纪至少已报道了4个显著的同位素负向漂移.以往多数研究认为这些同位素变化可做为这个时期全球地层对比的工具,而近年的研究表明可能并非如此.本文核查了华南各地伊迪卡拉系取得的碳同位素分析数据,并分两个不同时期在古地理图上投点,发现在同一时期不同沉积环境背景下碳同位素值(δ13C)空间分布变化很大,但均显示出从浅水台地到深水盆地相区由正变负的明显趋势,变化幅度高达11‰.在纵向分布上,重要新生物类群或生态类型的出现往往发生在碳同位素由负异常向正偏转折期,在正偏期明显丰富多样.如果碳同位素负偏移反映了海洋巨大溶解有机碳库的氧化过程,则碳同位素正偏期的生物群快速发展和显著负异常可能代表了有氧和缺氧/富硫两种完全不同的环境条件.我们认为黄铁矿或硫化物的大量析出对海洋富硫状态解除有重要贡献,而后者可能是促进伊迪卡拉生物群演化的重要环境因素之一.
The most prominent isotopic negative anomaly and major biological evolution in the history of Idiacalatus are the most important characteristics, and so far at least 4 significant negative excursions of isotopes have been reported in the Idiacaran of South China. Most previous studies suggested that these isotopic variations could be used As a tool for the global stratigraphic comparison of this period, and recent studies have shown that this may not be the case.The carbon isotope analysis data obtained by the Idikka series in different parts of South China were checked and the ancient geographical maps were cast in two different periods, In the same period, the spatial distribution of carbon isotope values (δ13C) varied greatly under different depositional environments, but all showed obvious trends from negative to negative for the phase from shallow water platform to deepwater basin, with a variation range up to 11 ‰. In the longitudinal distribution, Occurrence of important new taxa or ecotypes often occurs when the carbon isotope shifts from a negative anomaly to a positive defoliation, and is rich and diverse in positive deviations. If the carbon offset negative shift reflects the oxidation of the marine dissolved organic carbon pool, The rapid development of the carbon isotope normal biota and the significant negative anomalies may represent two distinct rings, aerobic and anoxic / sulfur-rich Conditions. We think a lot of pyrite or sulfide precipitation of the marine sulfur-rich state has released an important contribution, which may be important to promote environmental factors Ediacaran biota evolution.