伊利石^(40)Ar-^(39)Ar年龄的统计分析与成藏期

Statistics Analysis of Illite ^(40)Ar-^(39)Ar Ages and Petroleum Accumulation Period

为了确定鄂尔多斯盆地苏里格气田的成藏年代,通过提取砂岩储层中的黏土质填隙物,分离分级成<0.5、0.5~1.0、1.0~2.0μm的分样品,进行伊利石激光阶段加热^(40)Ar‐^(39)Ar定年.等时线年龄是自生伊利石与碎屑伊利石的混合年龄.通过趋势分析和回归分析分别获得极小的趋势年龄和极小的回归年龄,该年龄比较接近自生伊利石年龄.测试结果表明,伊利石的等时线年龄介于160.9~232.0 Ma之间,为自生伊利石与碎屑伊利石的混合年龄.采用数理统计方法获得极小趋势年龄和极小回归年龄分别为151.7 Ma和152.4 Ma,该年龄比较接近自生伊利石年龄,代表了热流体活动和油气成藏时间.

For determining the hydrocarbon accumulation ages of Sulige gas field in the Ordos basin,pore‐filling clay materials were extracted from reservoir sandstones and separated into frictions of<0.5,0.5-1.0 and 1.0-2.0μm,then ^(40)Ar‐^(39)Ar dating of illite was dealt with laser step‐heating.The isochron age is a mixed age of authigenic illite and detrital illite.Through trend analysis and regression analysis,minimum trend age and minimum regression age are obtained,which are more close to authigenic illite ages.The result shows that the isochron ages of illite minerals range from 163.1 Ma to 224.3 Ma,which are the mixed ages of authigenic illite and detrital illite.Based on mathematical statistics method,the minimum trend age and the minimum regression age are extrapolated to be 151.7 Ma and 152.4 Ma,respectively,which are supposed to be more close to authigenic illite ages,representing the time of thermal fluid activity and hydrocarbon accumulation.