作　　者： ; ; ; ; ; ;

机构地区： 西北大学地质学系大陆动力学国家重点实验室

出　　处： 《中国地质》 2013年第5期1453-1465,共13页

摘　　要： 油气成藏年代学是多旋回叠合盆地油气成藏动力学研究的热点问题.运用钻井岩心样品的自生伊利石同位素定年和流体包裹体间接定年方法,探讨分析了鄂尔多斯盆地东北部二叠系多期次油气成藏的时间和期次.含油气砂岩自生伊利石年龄以较宽的时间域分布在178～108Ma,测年数据的统计分布特征指示二叠系原生油气成藏时间主要集中在175～155Ma和145～115Ma两组主值年龄区间,相应的峰值年龄为165Ma和130Ma.流体包裹体测温数据的统计分析与其宿主砂岩磷灰石裂变径迹热史模拟路径的投影关系表明,二叠系不同层段共同经历了与90～78℃和125～118℃两组统计峰温相应的162～153Ma和140～128Ma两期原生油气成藏事件,其中的上二叠统则还经历了统计峰温接近98C、峰值年龄接近30 Ma的一期次生油气成藏事件.由此认为,鄂尔多斯盆地东北部二叠系不同层段在中生代早—中期的多旋回沉降增温过程至少经历了165～153Ma和140～128Ma的两期原生油气成藏作用,上二叠统则在晚白垩世以来盆地后期抬升改造阶段的构造动热转换过程经历了接近30 Ma的一期次生油气成藏作用. Geochronology of oil-gas accumulation （OGA） is a key research frontier for petroleum reservoir-forming dynamics in the multi-cycle superimposed basin. The OGA timing and stages of the Permian reservoirs in northeastern Ordos Basin （OB） are constrained in this paper by K-Ar dating of authigenic illite （AI） and indirect dating of fluid inclusions （FI） from oil-gas-bearing sandstone core samples of the Lower-Upper Permian period. AI dating results of the Permian samples show a wide time span of 178~ 108 Ma and a spatial decreasing trend from 178~122 Ma in the south to 160-108 Ma in the north. The distribution of the AI ages generally reveals 2-stage primary OGA of the Permian reservoirs, which were mainly developed in the time spans of 175~155 Ma and 145~115 Ma respectively with 2-peak ages of 165 Ma and 130 Ma. Additionally, the FI temperature peaks of the samples and their projected ages on AFT thermal path of the FI-host rocks not only statistically present two groups with a low and a high peak temperatures in ranges of 90~78 ~C and 125~118 ~C, respectively corresponding to 2-stage primary OGA processes of 162~153 Ma and 140~128 Ma in the Permian reservoirs; nevertheless, there is also a medium temperature group with the peak of 98 ~C in agreement with a secondary OGA process of ca. 30 Ma in the Upper Permian reservoirs. An integrated analysis of the AI and FI ages with the regional tectonic thermal evolution reveals that the Permian reservoirs in the northeast OB mainly experienced 2-stage primary OGA processes of 165~153 Ma and 140~128 Ma during the Mid-Early Mesozoic multi-cycle burial heating processes, and then the Upper Permian reservoirs further experienced 1-stage secondary OGA of ca. 30 Ma in accordance with a critical tectonic conversion from the slow to rapid uplift-cooling process during the Late Cretaceous-Neocene period.

关 键 词： 鄂尔多斯盆地东北部 二叠系砂岩储层 自生伊利石定年 流体包裹体分析 油气成藏年代学

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