多种剥蚀厚度恢复方法在内蒙古雅布赖盆地侏罗系和白垩系中的应用及其地质意义

剥蚀厚度恢复是进行盆地埋藏史、热演化史、油气成藏等定量分析的基础。文中利用镜质体反射率法、流体包裹体法、声波时差法和地层厚度趋势法等多种方法,恢复了内蒙古雅布赖盆地侏罗系和白垩系剥蚀厚度。计算结果表明,侏罗系和白垩系总剥蚀厚度为1610.9~2177.0,m;在流体包裹体法和地层厚度趋势法约束下,恢复的侏罗系剥蚀厚度为930.2~1395.3,m,白垩系剥蚀厚度为0~612.1,m。雅布赖盆地侏罗系剥蚀厚度“北大南小”,白垩系剥蚀厚度“南大北小”,反映盆地改造强度具有晚侏罗世南弱北强、早白垩世南强北弱的特征。大规模隆升剥蚀,导致地层温度下降、烃源岩遭到破坏,一定程度上制约着雅布赖盆地的烃源岩成熟演化以及油气生成。

Application of multi-methods for recovering denuded strata thickness of the Jurassic and Cretaceous in Yabrai Basin of Inner Mongolia and its geological significance

Recovery of denuded strata thickness is the foundation of making quantitative analysis of basin burial history,thermal history and hydrocarbon accumulation. In this paper,the denuded thickness of the Jurassic and Cretaceous in Yabrai Basin of Inner Mongolia was calculated by the methods of vitrinite reflectance(R_O),fluid inclusion,interval transit-time and trend surface of formation thickness. The analysis results show that the total denuded thickness of the Jurassic and Cretaceous is 1610.9-2177.0,m, and that of Jurassic and Cretaceous is 930.2-1395.3,m and 0-612.1,m respectively under the constraint results calculated by fluid inclusion and trend surface of formation thickness methods. The denuded thickness of Jurassic appears larger in north and smaller in south, while that of Cretaceous shows diametrically opposed as larger in south and smaller in north. The spatial distribution characteristics of denuded strata thickness indicate that the intensity of tectonic uplift in north was much stronger than that in south during the Late Jurassic and interconverted during the Early Cretaceous. The formation temperature descended and the source rocks were destroyed after the large scale uplifting and denudation,and that restricted the maturity and thermal evolution of source rocks and even the hydrocarbon generation in Yabrai Basin to a certain extent.