川西凹陷异常高压特征及成因分析

The Abnormal High Pressure Features in Western Sichuan Sag and Origin Analyses

川西前陆盆地上三叠统异常高压有其特有的分布特征。通过对欠压实作用、生烃增压作用、粘土矿物脱水增压作用、构造挤压作用等几种可能的成因机制分析认为:喜山期构造挤压是形成并维持梓潼凹陷上三叠统异常高压现今格局的主控因素。川西前陆盆地沙溪庙组南北差异沉积作用使得上三叠统地层致密化程度北高南低,造成其成因机制在南北地区的差异性。

The abnormal high pressures of the Upper Triassic Series foreland basin in western Sichuan have its peculiar distribution features.Through the analyses on some kinds of possible origin mechanisms of lack of compacting action,hydrocarbon generation and increasing compacting action,clay mineral dehydration increasing compaction action and structural squeezing action,it is thought that the structural squeezing in Xishan time is the main control factor of forming and maintaining abnormal high pressures' present patter in the Upper Triassic of Zitong sag.The discrepancy sediment action between the north and south in Shaximiao group of western Sichuan foreland basin makes the north have a high densification level of the Upper Triassic formation and the south a low one,which causes the discrepancy of origin mechanism between the north and south areas.