龙门山逆冲推覆带构造特征及勘探潜力分析

STRUCTURAL CHARACTERISTICS AND EXPLORATION POTENTIAL OF THE THRUST BLOCK IN LONGMENSHAN

根据龙门山构造带的变形特征,自西向东可以划分茂汶韧性剪切带、龙门山叠瓦冲断构造带和龙门山逆掩推覆构造带。龙门山逆掩推覆构造带可以划分为前山带和隐蔽带两个亚带,具备良好的成藏地质条件。对于前山带,相对稳定的构造部位和良好的封盖保存条件是主控因素。对于山前隐蔽带,古今构造叠合、相对活动的构造和裂缝发育部位是主控因素。据此预测出关口-水口场隐伏断裂带上盘的磁峰场断高带,高家场、水口场、油榨坨、石板滩构造带和下盘的平落坝,邛西、大邑、鸭子河背斜是勘探天然气最有利的地区。

The Longmenshan structural zone is divided into Maowen ductile shear zone, Longmenshan imbricated thrust structural zone and Longmenshan thrust nappe structural zone from west to east according to its deformation characteristics. And the Longmenshan thrust nappe structural zone can be further divi-ded into two subzones, foremountain zone and concealed zone where is idea position for hyarocarbon accumulation. As to the foremountain zone, the relativehy stable structure and good closing and capping capability are the master elements for hydrocarbon accumulation. And for the mountain front concealed zone, the master elements are the polymerzation of old and present structure, relatively active structure and where fissures develop. Thus it is predicted that, the most favorable exploration area for natural gas is the Cifengchang high part in the hanging wall of concealed fault belt in Guankou-Shuikouchang, the Gaojia-chang, Shuikouchang, Youzhatuo and Shibantan structural zones and Pingluoba in the footwall, as well as Qiongxi, Dayi and Yazibe anticlines.