【摘要】 山西省兴县奥陶系马家沟组第五段第一亚段（马五₁）主要由沉积于低能的陆表海环境中的泥晶灰岩及经岩溶作用改造而成的砾状泥晶灰岩组成。由于溶有有机碳的大气淡水淋滤,泥晶方解石的δ¹³C值,在—12.4‰至—2.4‰范围内,平均为—5.89‰。没有变化的原始海相泥晶方解石的δ¹⁸O值高,为—4.3‰。大部分泥晶方解石有低的δ¹⁸O值,最低的δ¹⁸O值为—13.1‰;平均δ¹⁸O值为—6.85‰。锶含量为0.13×10^-6—98×10^-6,平均值为30.5×10^-6,Na₂O含量在0%—0.04%范围内,其平均值为0.02%。Fe₂O₃和MnO含量分别在0.05%—6.21%与0.01%—0.08%范围内,其平均值分别为1.03%与0.02%。方解石充填物较泥晶方解石有较低的δ¹³C,δ¹⁸O值和Fe₂O₃,MnO,Na₂O含量,以及略高的锶含量。说明方解石充填物受淡水影响较强,且形成于不同的埋藏深度。方解石充填物包裹体的均一温度为52—289℃,平均为162℃;盐度ω（B）为0.9%—15.3%,平均为5.9%。说明大部分方解石充填物形成于较深的埋藏条件下。更多还原

【Abstract】 The first submember of the fifth member of the Lower Ordovician Majiagou Formation in Xingxian,Shanxi Province,consists mainly of micrite deposited in low—energy epicontinental environments and psephitic micrite resulting from reworking of original carbonates by palaeokarstification. Through leaching by meteoric water dissolving CO₂ from organic carbon,the δ¹³C values of microcrystalline calcite range from —12.4‰ to —2.4‰ with a mean of —5.89‰.The unaltered marine original microcrystalline calcite has high δ¹⁸0 values （—4.3‰）.Most microcrystalline calcite has low δ¹⁸O values,the lowest value being —13.1‰ and the mean being —6.85‰.It has low values of Sr and Na₂O,ranging 0.13×10^-6 —98×10^-6 and 0%—0.04% with means of 30.5×10^-6 and 0.02% respectively.The values of Fe₂O₃ and MnO range 0.05% — 6.25% and 0.01% —0.08% with means of 1.03% and 0.02% respectively.Calcite filling has lower values of δ¹³C,δ¹⁸O,Fe₂O₃,MnO and Na₂O,and a little higher values of Sr than micrite, indicating that calcite filling has been more strongly affected by leaching of meteoric water and formed at different burial depths.The homogenization temperatures of fluid inclusions of calcite filling range 52—289℃ with a mean of 162℃ and the salinity （ω （B）） of fluid inclusions of calcite filling ranges 0.9%—15.3% with a mean of 5.9%,indicating that calcite filling formed at relatively deep burial conditions.更多还原