准噶尔盆地西部侏罗系层序地层特征

SEQUENCE STRATIGRAPHY OF JURASSIC IN WEST JUNGGAR BASIN

综合利用露头、岩芯、钻并、地震和古生物等资料，应用地层基准面原理，对准噶尔盆地西部侏罗系进行了高分辨率层序地层学研究。识别出６个不整合面即层序边界，按此物理界面将诛罗系划分出５套层序，建立起了与盆地统一的等时地层格架。各层序的内部构型呈现多种形式。层序１的长期基准面上升旋回由砂砾质辫状河冲积扇构成，长期基准面下降旋回由滨浅湖→三角洲前缘→三角洲平原构成。层序２的长期基准面上升半旋回呈现由底部充填于切蚀谷的辫状河河道砂砾岩→网状河→曲流河→三角洲序列；长期基准面下降半旋回主要由滨浅湖→三角洲前缘构成。层序３的长期基准面上升半旋回由辫状河→曲流河→三角洲构成；长期基准面下降半旋回由滨浅湖→三角洲前缘相构成。层序４、层序５以发育基准面上升半旋回为主。

The high-resolution seguence stratigraphy of the Jurassic System in west Junggar Basin was studied and six unconformity surfaces (or sequence boundaries) were recognized - The Jurassic System could be divided into five sequences according to the surfaces, and an isochronic formation skeleton was set up which coincides with Junggar Basin. The long-term base level rising cycle of sequence-I is composed of braided river alluvial fan; the long-term base level falling cycle of sequen-1 consists of shore-shallow lake→delta front→,delta plain . The long-term base-level rising cycle of sequence-2 is composed of basal braided channel sandstone-conglomerate→meandering stream→ delta; its falling semi-cycle mainly consists of shore-shallow lake→.delta front. The long-term base-level rising semicycle of sequence-3 is composed of braided river→ meandering stream→ delta; its falling semi-cycle consists of shore-hallow lake→ deta front.