中文摘要：

鄂尔多斯盆地下古生界石灰岩的岩相及碳、氧稳定同位素组成变化大,具有多种成因类型。通过薄片鉴定、岩石及矿物微区碳、氧稳定同位素测试以及包裹体测温资料研究,发现正常海水成因的泥晶灰岩及颗粒灰岩具有较高的δ18O、δ13C;受淡水淋滤、溶蚀的颗粒灰岩、角砾泥晶灰岩、豹斑含云灰岩或灰云岩的δ13C随淡水淋滤及溶蚀程度升高而明显降低,但其δ18O变化较小;去膏化成因的巨晶次生灰岩在阴极发光下具环带结构,并具有较低的δ18O、δ13C,去云化成因的中—细晶次生灰岩多呈麦粒或蚕蛹结构,其δ18O、δ13C相对较高;早期及表生淡水方解石胶结物的δ18O、δ13C均为低值,Mn离子含量低,阴极发光暗淡;晚期热液方解石胶结物具异常低的δ18O、δ13C,包裹体均一温度介于100～150℃,富含Mn离子,阴极发光明亮。研究结果表明,岩相特征、碳、氧稳定同位素组成以及包裹体测温数据是确定石灰岩沉积、成岩环境以及成因类型的重要指标。

英文摘要：

The lithofacies features and carbon and oxygen stable isotopes composition of Lower Paleozoic limestones in Ordos Basin change in a wide range.Based on the identification of rock thin section and cathode luminescent image,the measurement of carbon,oxygen stable isotopes of rocks and micro area of minerals,the analysis of liquid inclusion and its homogenous temperature testing,it is found that δ18O and δ13C values of micrite,grain limestone formed in normal sea water are the highest,δ18O values of grain limestone,breccia micrite,porphyritic dolomite-containing limestone or dolomitic limestone leached by meteoric water as well as freashwater calcite cements changes in a narrow range,and δ13C values of them obviously decreased with increasing of freashwater leaching degree.δ18O and δ13C values of megacryst limestone formed in de-gypsum reaction are low,which commonly exhibit zonal structure in cathodoluminescence thin section.δ18O and δ13C values of Middle-fine crystalline limestones are higher than that of megacryst limestone,which were formed in the dedolomitization reaction going with sulphate dissolution and commonly exhibit pupa structure.δ18O and δ13C values of late hydrothermal calcite cements are the lowest,in which liquid inclusion homogenous temperature varies from 100 to 150℃.Late calcite cements contain more Mn2＋ and show brighter aurantium cathodoluminescence than freashwater calcite cements.The results indicate that the petrographic characteristics of limestone,carbon and oxygen stable isotope composition,and liquid inclusion homogenous temperature are important indexes to identify diagenetic environment and facies of limestone.