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藏南地区在大地构造上位于青藏特提斯构造域南部,包括冈底斯山—念青唐古拉微板块、雅鲁藏布江缝合带和喜马拉雅微板块三个大地构造单元。经历了三个构造演化阶段:晚三叠世—侏罗纪为扩张洋盆地阶段;白垩纪为消减洋盆地阶段;早第三纪为碰撞敛合后残余海盆地阶段。该区是我国中—新生代海相地层发育最全、厚度最大的地区,三叠系—第三系总厚逾万米。不同时期、不同性质的盆地叠加构成复合盆地,组成四个复合盆地带,并在其上发育了七个构造残块型海相小盆地。其中,岗巴盆地为Ⅰ类远景盆地,面积6750km~2,烃源岩厚度1500m,属较好级别,目的层侏罗系—白垩系保存完整,构造变形相对较弱,褶皱保存完整;定日盆地次之;其它盆地含油气远景欠佳。
The southern Tibet is geologically located in the southern part of the Tethys tectonic domain of the Qinghai-Tibet Plateau, including the Gangdese-Nyainqentanglha Plate, the Brahmaputra suture and the Himalayan microplate. Experienced three stages of tectonic evolution: the Late Triassic-Jurassic period for the expansion of the ocean basin; the Cretaceous period for the abatement of the ocean basin; the Early Tertiary for the residual marine basin after the collision and convergence. This area is the most developed and the largest in China’s Meso-Cenozoic marine strata. The Triassic-Tertiary total thickness is over ten thousand meters. In different periods and different types of basins, the composite basins are superimposed to form four composite basin belts, and seven structural residual block marine small basins are developed thereon. Among them, Gamba Basin is a Class Ⅰ prospect basin with an area of 6,750km 2 and a source rock thickness of 1,500m. The Jurassic-Cretaceous strata of the target layer are well preserved with relatively weak tectonic deformation and complete folds. The basin is second; other basins have poor prospects for oil and gas.