库车-塔北地区中生代关键变革期主要不整合及古隆起地貌特征

沉积盆地关键变革期发育的主要不整合及大型古隆起的研究是揭示盆地动力学演化和油气聚集的关键。文中综合分析地震、测井及野外露头等资料,利用不整合削截点和上超点追踪等方法,揭示了库车-塔北地区中生代主要不整合、古隆起地貌特征及其对盆地动力学演化的响应关系。研究表明库车-塔北地区在中生代经历了二叠纪末、三叠纪末、侏罗纪末和白垩纪末4次关键变革,相应产生了TT,TJ,TK和TE 4个区域性角度不整合,并对盆地的构造古地貌产生了重要影响。二叠纪末的变革主要以研究区中部和西部大型古隆起带的发育为特征,不整合TT围绕构造古隆起分布,最大剥蚀量达1 200 m。三叠纪末的变革致使研究区的古隆起带发生大范围隆升,产生了广泛分布的不整合TJ,其最大剥蚀量为400 m。侏罗纪末的构造变革致使研究区中西部再次隆升,不整合TK发育,最大剥蚀量为500 m。白垩纪末的变革主要以研究区西部温宿古隆起的发育为特征,伴生的不整合TE分布范围较小,剥蚀量最大为300 m。研究区中生代的古隆起地貌可划分为高隆区、斜坡区和坳陷区等3个单元,其中斜坡区发育的不整合三角带是形成有利岩性地层圈闭的重要部位。研究表明中生代经历的4次构造变革与盆地周边发生的4次碰撞造山作用有关。

Characteristics of major unconformities and paleo-geomorphology during the Mesozoic key transformation stages in Kuqa-Tabei area

Research on major unconformities and large-scale palaeo-uplifts developed during the key transformation stages in sedimentary basins is key to revealing the basin dynamics evolution and hydrocarbon accumulation.Based on the integrated analysis of seismic, logging and outcrop data, we demonstrated the characteristics of the Mesozoic major unconformities and palaeo-geomorphology, as well as how they are influenced by the dynamics evolution of Kuqa-Tabei basins through tracking unconformity truncation and onlap points, etc.Results show that the study area in the Mesozoic undergone four key transformation stages, namely the Late Permian, Late Triassic, Late Jurassic, Late Cretaceous stages; in turn four regional angular unconformities, namely TT, TJ, TK and TE, which have brought significant impact on the basinal tectonic palaeo-geomorphology.The transformation occurring at the Late Permian was mainly characterized by the development of large-scale palaeo-uplift belts in the central and western parts of the study area, and the unconformity TT was mainly distributed around the palaeo-uplifts with the maximum denudation thickness of 1 200 m.The tectonic movement of the Late Triassic resulted in a significant reactivation of the palaeo-uplift belts in the study area, and the unconformity TJ produced is of wide range with the maximum denudation amounting to 400 m.The tectonic movement taking place in the Late Jurassic resulted in another stage of uplifting and denudation in the central and western of the study area, and consequently the unconformity TK was developed with the maximum denudation of 500 m.The transformation of the Late Cretaceous is mainly characterized by the development of the Wensu palaeo-uplift at the western margin of the study area, and its associated unconformity TE is of limited distribution with the maximum denudation amounting to 300 m.Three geomorphologic units are recognized in the Mesozoic palaeo-highs, that is the uplift high, slope and depression areas.Around the slope area formed unconformity triangle zones, which are favorable for the development of litho-stratigraphic traps.In addition, it's believed that the four collisional orogeneses occurring around the basins had driven the formation of four transformation stages in the Mesozoic.