川西前陆盆地上三叠统须家河组二段可容空间转换系统的成因与演化

要:川西前陆盆地上三叠统须家河组二段层序发育时,由于构造运动的特点,盆地不同位置可容空间变化具有不统一性。盆地基底差异沉降导致相对湖平面变化的不同,其内部水深既存在增加带,又存在减小带,还存在着不变带。前陆盆地在同一时期内部不同位置可容空间不均衡变化的现象,称之为可容空间转换系统。可容空间转换系统可细分为转换面、转换带、转换体等次级构造单元。川西前陆盆地须家河组二段可容空间转换系统沿龙门山造山带向盆地,呈北东向长条状分布,依次可划分为主可容空间转换带(Ⅰ)、主可容空间增加带(Ⅱ)、主可容空间转换带(Ⅲ)、主可容空间减小带(Ⅳ)、次可容空间转换带(Ⅴ)、次可容空间增加带(Ⅵ)、次可容空间减小带(Ⅶ)等7个可容空间转换带。这些可容空间转换系统主要是由于构造应力场的挤压沉降作用和推覆隆升作用在平面上的交互出现所致。主可容空间转换带是目前发现气藏数量最丰富,产量最高的地区,也是目前的技术条件所能达到的现实勘探目标区。

Genesis and evolution of accommodation transformation systems in 2nd member of Upper Triassic Xujiahe Formation,Chuanxi foreland basin

During deposition of the 2nd member of Upper Triassic Xujiahe Formation in Chuanxi foreland basin, the variation of accommodations in different locations within the basin are not unitary, due to the tectonic movement.According to the differential subsidence of basement and relative changes of lake level, it is believed that the water depth within the foreland basin can be divided into an increasing zone, a decreasing zone, as well as an invariant zone.The uneven changes of accommodations in the same period in a foreland basin are characterized as accommodation transformation system. Accommodation transformation system can be subdivided into several internal structural units,such as transformation body and transformation plane. During the deposition of the middle and lower 2