黑龙江东部晚中生代盆地群构造层划分及构造沉积演化

黑龙江东部盆地群包括现今残留的三江盆地、勃利盆地、鸡西盆地、虎林盆地和宁安盆地等。根据地层间的不整合关系可将晚中生代盆地群划分为4个构造层, 盆地演化经历了3次不同背景下的伸展阶段和3次构造反转。构造层Ⅰ (绥滨组和东荣组) 发育于SN向断陷槽内; 构造层Ⅱ (滴道组、城子河组和穆棱组) 发育于NE-NNE向的弧后伸展走滑环境; 构造层Ⅲ (东山组) 沉积时期, 本区又发生一次伸展减薄裂解作用; 而构造层Ⅳ (猴石沟组、海浪组、七星河组和雁窝组) 则发育于NW-NNW向挤压环境, 充填一套粗碎屑沉积。黑龙江东部盆地群的形成和演化受蒙古-鄂霍茨克海碰撞闭合的影响和东部古太平洋板块的俯冲作用及若干外来地体的拼贴作用控制, 其中太平洋板块向大陆俯冲引起的局部地幔对流和岩石圈显著减薄的拆沉事件是盆地形成的主要动力学机制。

Subdivisions of structural layers and tectonic-sedimentary evolution of eastern basins in Heilongjiang in Late Mesozoic

Eastern basins in Heilongjiang Province include rudimental Sanjiang Basin, Boli Basin, J ixi Basin, Hulin Basin and Ning’an Basin. According to stratigraphic unconformity, the LateMesozoic basins would be sub-divided into four structural layers, which experienced some extension stages in three different tectonic settings and three tectonic inversion stages. Structural layer I ( Suibin and Dongrong Formations) developed in NS oriented rift trough; structural layer II (Didao, Chengzihe andMuleng Formations) developed in back-arc extension slip set-tingwith NE-NNE trend; during the depositional period of structural layer III (Dongshan Formation ) , this area extended again; while structural layer IV (Houshigou, Hailang, Qixinghe and Yanwo Formations) developed in NW-NNW oriented comp ressional setting, filling with coarse sediments. The formation and evolution of the eastern basins in Heilongjiang were impacted by the collision and closure ofMongolia—Okhotsk Sea, and controlled by the subduction of the eastern Pacific Plate and the matching function of some foreign bodies. The localmantle convection and significant lithospheric thinning caused by the subduction from the Pacific Plate to the mainland are the main dynamic mechanisms of basin-formed.