松辽盆地徐家围子断陷构造演化

EVOLUTION AND GAS-ACCUMULATION OF XUJIAWEIZI DEPRESSION IN SONGLIAO BASIN

徐家围子断陷是松辽盆地深层一个具代表性的含气断陷。研究表明断陷演化分为火石岭—沙河子期 (J3 h K1sh)和营城期 (K1ych)两个阶段。J3 h K1sh期为断陷主要发育阶段 ,断陷为NW向 ,受NW向基底断层伸展控制。K1sh末期存在一次较强的挤压反转 ,断陷发生褶皱与断层逆冲反转。K1ych期具坳陷性质 ,盆地转为NNE向。J3 h K1sh期断陷发育受NW SW向左行扭动应力场影响 ,NW向断陷段具有走滑拉分特点。沙河子期是烃源岩主要沉积期。J3 h K1sh期形成的横向转换构造、断层斜坡和反转期形成的反转背斜 ,最有利于深层气聚集成藏。

Songliao Basin underwent active rifting in the Late Jurassic Huoshiling to Early Cretaceous Yingcheng (J 3h_K 1ych),followed by a post_rift phase in the Early Cretaceous Denglouku_Nenjiang(K 1d_K 1n)and a reversion phase in the Late Cretaceous_Cenozoic(K 2?K z).The Xujiaweizi fault_depression is a representative gas_bearing sub_basin in the lower part of Songliao Basin in the rifting phase.During the rifting phase,the two evolutive phases of Xujiaweizi fault_depression were found:the main faulting period in the Huoshiling_Shahezi(J 3h_K 1sh)along the NW?SE direction,and the asgging period in the Yingcheng(K 1ych).In the end of K 1sh,Xujiaweizi depression reversed.The resource(K 1sh)deposited in the NW extending sub_basin.This discussing is of great benefit to defining the Later Mesozoic stress_field in northeastern China and to finding the new gas_field in the lower part of Songliao Basin.