大兴安岭两侧控盆断裂域地球物理场基本特征与地质意义

大兴安岭重力梯度带两侧控盆断裂域的地球物理场基本特征与构造属性存在巨大差异,本文通过研究大兴安岭西坡德尔布干断裂以及松辽盆地中央孙吴—双辽断裂附近的重力、大地电磁测深资料,并结合满洲里—绥芬河地学断面(GGT)资料,对德尔布干断裂和孙吴—双辽断裂的控盆作用以及地质意义进行论述.研究结果表明:德尔布干断裂控制了海拉尔—根河盆地的演化,并在区域动力作用下被改造;使断裂深部倾向北西,浅部倾向南东.孙吴—双辽断裂控制着松辽盆地的形成演化,断裂深部倾向近垂直,浅部主要受太平洋西向俯冲和蒙古—鄂霍茨克洋闭合的影响,在浅部产生双向逆冲推覆构造.德尔布干断裂位于盆地的附近,由于岩浆沿断裂的侵入与喷发,因此有利于生烃也有利于形成重要的金属成矿带;孙吴—双辽断裂位于盆地中央,含油气层附近的双向逆冲推覆构造可能更有利于油气的聚集,使松辽盆地成为最重要的产油盆地之一.

Features of the geophysical field of basin-control fault regions on either side of the Da Hinggan Mountains and geological implications

There is a huge difference of the geophysical field and geological structure of the regions around basin-control faults on either side of the Da Hinggan Mountains evidence by a gravity gradient zone.In this paper,we analyze the characteristics of the gravity and magnetotelluric sounding data in the Derbugan fault region, western slope of Da Hinggan Mountains and Sunwu-Shuangliao fault region in the central Songliao basin. Based on the characteristics and the GGT profile of Manzhouli-Suifenhe, we evaluated the control effect of the Derbugan fault and Sunwu-Shuangliao fault on the formation of the basin.Results suggest that the Derbugan fault controlled the evolution of the Hailar-Genhe basin which was reformed by the regional dynamics.Currently,the Derbugan fault is separated into two parts, of which the deep part dips to north-west while the shallow part to south-east.The Sunwu-shuangliao fault controlled the formation and evolution of the Songliao basin, which is also separated into two parts; the deep part of which is nearly vertical, and the shallow part was affected by both the westward subduction of the Pacific Ocean and the closure of the Mongol-Okhotsk Ocean,resulting in the bidirectional thrust-nappe structure.The intrusion and eruption of magma along the Derbugan fault on the edge of the basin might create favorable conditions for hydrocarbon generation and major metallogenic belts.The Sunwu-Shuangliao fault, which is located in the center the basin,nearby the bidirectional thrust-nappe structure, might also provide an good environment for oil and gas accumulation,and made the Songliao basin one of the most important petroleum basins.