关键词: 断阶带, 火山岩体, 幕式活动, 沉积相, 分布, 松辽盆地

Abstract:

A series of fault terrace belts were found in Xujiaweizi fault depression, from the margin to the center of the depression, in late Juassic to early Cretaceous.The synsedimentary faults,controlling the generation of fault terrace belts,segmented the secondary geological units,such as uplift belt,slope belt and hollow zone.Xujiaweizi fault-depression can be divided into north and south regions:the former consists of west and east two half-grabens;while the latter is composed of three half-grabens.Each half-graben generally consists of basin-margin uplift,steep-slope fault terrace,hollow zone and gentle-slope fault terrace.There is a secondary uplift between two half-grabens. The development of fault terrace belts controlled the topographies from the margin to the sag in the basin, and hence controlled the types of depositional facies and their distributions,too. Moreover, volcanic activities induced by faulting or associated with faulting resulted in the infilling of volcanic materials in the basin,and the transformation of secondary tectonic pattern and topography in the basin, which would, therefore, controlled the types and distribution of sedimentary facies.It is susgested that the distribution of volcanic massifs and sedimentary facies have been controlled by the fault terraces in Xujiaweizi fault depression.Such control should have been affected by multiple factors, and cannot be easily explained with a single meachanism.

Key words: fault terrace belt, volcanic massif, episodic movement, sedimentary facies, Songliao basin