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研究了南京汤山观音台组顶部、仑山组和红花园组底部的微量元素、稀土元素和碳、氧同位素,基于观音台组顶部白云岩中白云石和方解石δ~(18)O 值的相似性,认为它是在成岩作用初期由交代作用形成的准同生白云岩。依据同位素分析,所研究层段的碳酸盐岩主要形成于埋藏成岩环境,未经历大气淡化成岩阶段。依据地层多重划分概念修订了观音台组和仑山组的界线。依据碳同位素与有关地区对比探讨了寒武系与奥陶系界线,界线附近δ~(13)C 值仅见小的负偏移,反映这一时期海平面的升降幅度较小。
The trace elements, rare earth elements and carbon and oxygen isotopes at the top of the Tangshan Guanyintai Formation, the Lunshan Formation and the Honghuayuan Formation in Nanjing were studied. Based on the similarity of the δ 18 O value of dolomite and calcite in the top dolomite of the Guanyin Formation It is considered as a quasi-syngenetic dolomite formed by metasomatism in the early stage of diagenesis. According to isotope analysis, the carbonate rocks in the studied intervals mainly formed in burial diagenetic environment and did not undergo desalination and diagenesis stage. According to the concept of multi-stratification of strata, the boundary between Guanyin and Lun Shan was revised. Based on the correlation between carbon isotopes and the related regions, the Cambrian and Ordovician boundary lines are discussed. The δ ~ (13) C values near the boundary show only a small negative offset, indicating that the sea level rise and fall is small during this period.