【摘要】 研究了塔里木盆地巴楚地区寒武至奥陶系海相碳酸盐岩的碳、氧同位素组成特征 ,分析了影响碳酸盐岩碳同位素变化的原因 .结果表明 ,寒武 -奥陶系海相碳酸盐岩的碳同位素的变化可能与海平面变化有密切联系 ,在早寒武世至中寒武世海退期 ,有机质产率及有机碳埋藏速率的下降导致了碳酸盐岩δ13 C值的降低 ;而在早奥陶世海侵期 ,有机质产率及有机碳埋藏速率的增加导致了碳酸盐岩 δ13 C值的增高 ;中寒武世海水中的硫酸盐含量高 ,硫酸盐细菌的还原作用使有机质氧化 ,从而导致碳酸盐岩δ13 C值降低 ;部分样品过低的δ13 C值可能与岩浆活动或火山活动释放的 CO2 参与分馏作用有关更多还原

【Abstract】 Composition features of carbon and oxygen isotopes in marine carbonate rocks of Cambrian Ordovician in Bachu area of Tarim Basin were researched. Factors influencing the variation of carbon isotope were analyzed. The results show that the variation of δ 13 C of the Cambrian Ordovician marine carbonate rocks is closely related to the changes of sea level. The slower organic carbon burial during sea level fall from the Early Cambrian to Middle Cambrian led to a decrease of the δ 13 C value of carbonate rocks of this stage. The rise of organic productivity together with a rapid burial of organic carbon during the rise of sea level in Early Ordovician led to an increase of the δ 13 C value of carbonate rocks of this stage Because of a high sulfate content in seawater in the Middle Cambrian, the reduction by sulfate bacteria caused an oxidation of organic matter, resulting in a decrease of the δ 13 C values. The negative δ 13 C value in some samples interbedded with volcanic rocks may be related to the fractionation of the CO 2 emitted from magmatic activity or volcanism.更多还原