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塔河地区奥陶系方解石脉和胶结物~(87)Sr/~(86)Sr值多高于围岩与同期海水,显示具有外来的、富~(87)Sr的流体的贡献。富~(87)Sr的流体可来自奥陶系抬升时期淡水对碎屑岩的淋滤作用,但也可来自深部的热液流体。不同成因的流体所沉淀的方解石Sr含量具有明显的差异。地层水δD-δ~(18)O关系证实了存在淡水的混合作用。淡水的混合导致了原油的厌氧生物降解,产生低δ~(34)S的黄铁矿与有机酸;有机酸促进了不整合面附近的岩溶作用。而方解石的均一化温度可达150～190℃,有意义地高于地层所经历的最高温度,支持了存在深部热液流体的活动,说明Sr很可能都来自寒武系或前寒武碎屑岩地层;该热液流体促进了寒武系碳酸盐岩发生热化学硫酸盐还原作用(TSR),产生H_2S气体和黄铁矿,其δ~(34)S值为18‰～22‰。热液流体的活动,导致了碳酸盐矿物的溶解-再沉淀作用。
The 87 ~ (87) Sr / ~ (86) Sr value of Ordovician calcite and cements in Tahe area is much higher than that of the surrounding rocks and the seawater of the same period, indicating the contribution of exotic 87 ~ Sr rich fluids. Fluids rich in ~ (87) Sr can be derived from the leaching of clastic rocks by freshwater during the Ordovician uplift, but may also come from deep hydrothermal fluids. There are obvious differences in Sr content of calcite precipitated by fluids of different origins. The δD-δ ~ (18) O relationship in formation water confirms the mixing effect of freshwater. The mixing of freshwater led to the anaerobic biodegradation of crude oil, resulting in low δ ~ (34) S pyrite and organic acids; organic acids promoted the karst near the unconformity. The homogenization temperature of calcite can reach 150-190 ℃, meaningfully higher than the highest temperature experienced by the formation, supporting the existence of deep hydrothermal fluids, indicating that Sr probably came from the Cambrian or Precambrian The hydrothermal fluids promoted the thermochemical sulfate reduction (TSR) of Cambrian carbonate rocks to produce H 2 S gas and pyrite with δ 34 S value of 18 ‰ ~ 22 ‰. The hydrothermal fluid activity leads to dissolution-reprecipitation of carbonate minerals.