北山盆地群侏罗、白垩系沉积体系及其分布、演化

通过地质调查并结合前人资料，研究了北山盆地群侏罗系与下白垩统的沉积体系类型及其分布、演化。结果表明：北山盆地群侏罗系及下白垩统为典型的内陆湖盆沉积，发育冲积扇、河流(以辫状河为主)、三角洲(包括扇三角洲、辫状河三角洲、曲流河三角洲)、湖泊等沉积体系；沉积体系的分布及演化主要受构造及古气候条件的影响，侏罗系及下白垩统属两个沉积旋回，每个沉积旋回大致可以划分为初始断陷期、强烈断陷期和断陷萎缩期3个沉积阶段；由于阿尔金断裂在侏罗纪时对北山地区南部影响较大，导致侏罗纪沉积呈现出一定的南北差异，表现为南部盆地断陷更为强烈．出现了较深湖相沉积，北部盆地断陷强度相对较弱，只出现滨浅湖沉积；早白垩世阿尔金断裂对本区影响不大，其沉积特征差异不明显。

The Jurassic to Cretaceous sedimentary systems and their distribution and evolution in the Beishan Basins group

According to detailed field geological survey and predecessor's material,the types of sedimentary systems from Jurassic to Cretaceous period and their distribution and evolution in the Beishan Basins group are analyzed. The Jurassic to Cretaceous System in the Beishan Basins are typical interior lacustrine basin deposits, which developed alluvial fan,stream (mainly braided stream) .delta (including fan-delta,braided delta,sinuosity stream delta) and lacustrine sedimentary systems. Structural movements and paleoclimate mainly controlled the sedimentary systems and their distribution and evolution. The Jurassic and Cretaceous System respectively belong to two sedimentary cycles. Each cycle can be roughly divided into three sedimentation stages, i. e. early fault depression stage,intense fault depression stage and fault depression shrink period. Because the Aerjin Fault had greater effect in the southern part of the Beishan area in Jurassic period, the Jurassic sedimentation presents some south and north difference. The basins in the south such as Zhongkouzi basin, Luotuoquan basin had stronger fault depression and developed deep lake deposition. The basins in the north such as Heiyingshan basin, Gongpoquan basin only developed shallow lake deposition. In the early Cretaceous epoch, however the Aerjin Fault had little effect on Beishan area,so the basins roughly had the same sedimentation features.