柴达木盆地“厚顶”构造及其形成机理

柴达木盆地“厚顶”构造现象甚为典型且分布广泛。这些“厚顶”构造可分为6种类型:尖顶屋脊式、双层结构式、圆顶帐篷式、断层叠合式、低丘式和草帽式。其在纵向上主要分布于第三系渐新统（E₃）下干柴沟组及中新统（N₁）上干柴沟组和上新统（$N^1_2$）下油砂山组中。其在横向上主要分布于盆地的北部、西部及中腹部地区。厚顶构造的形成机理是由于厚度较大的泥质岩类塑性地层在强烈挤压和扭动环境中逐渐形成的。对油气勘探而言,厚顶构造有较好的生、盖条件。储集层以裂缝类为主。

The "Thick Top" Structure and Its Formation Mechanism in Chaidam Basin

The "thick top" structure is typical and extensive occurrence in Chaidam basin. It can be divided into several types such as 1)tip roof back; 2)two-layer texture; 3)round top tent; 4)fault coincidence; 5)low mound, and 6)straw hat. In vertical direction, these types of struc-tures are mainly distributed in Oligocene (E₃), Miocene (N₁) and Pliocene (N₂¹) of the basin; in lateral direction, they are mostly in the north-ern, western and central areas of it. The mechanism of this structural formation is due to plastic argillaceous strata under the environment of intense compaction and wrench deformation. For petroleum exploration in it, the "thick top" structure is in favorable source-cap conditions, and the reservoirs formed are dominated bu fractured ones.