松辽盆地林甸断陷白垩纪沙河子期盆地次级构造单元与沉积体系

松辽盆地林甸断陷是由2个次级断陷构成的复合断陷。次级断陷由斜坡-断阶带、凹陷带、断隆带构成。盆地的次级构造单元控制了物源区、水系和沉积区的分布,控制了沉积体系的发育与类型。断阶带控制砂体的发育与展布,陡坡断阶带发育冲积扇-扇三角洲沉积体系,而缓坡断阶发育冲积扇-河流-三角洲沉积体系。断陷内部的断隆带起到分水岭的作用,两侧分别发育河流-三角洲体系。断裂的下降盘不仅可以作为沉积区,而且可以作为沉积物的通道,由此沉积物可以输送到沉积中心区域。由单断凹或双断凹控制的凹陷带发育细粒沉积,为滨湖沼泽和浅湖所占据,成为生油凹陷。

Structural Sub-Division and Depositional Systems of Lindian Fault Depression in the North Songliao Basin During Shahezi Stage of Early Cretaceous

Lindian fault depression of the Songliao Basin is composite in basin structure, which can be divided into slope-fault terrace zone, depression zone and fault uplift zone. Those sub-structural units controlled the contributions of provenances, stream systems and depositional areas, and also controlled the development of depositional systems and their types. The fault terrace zone controlled the occurrence and distribution of sand deposits, developing alluvial fan-fan delta system on the steep slope fault terrace and alluvial fan-fluvial-delta on the gentle slope fault terrace. The fault uplift zone was a drainage divide within the fault depression, developing fluvial-delta systems on its two sides. The hanging wall area of fault can be used not only as depositional area, but also as bypass for the sediments to the center area of deposition. The depression zone was controlled by a single fault or a couple faults, developing fine sediments of shore swamp and shallow lake, being a kind of source rock.