川西前陆盆地的“四川运动”及与油气的关系

川西前陆盆地和龙门山地区磷灰石裂变径迹的测定和计算机摸拟,为“四川运动”‘提供了新的信息。该区的“四川运动”共有4幕:第1幕发生在60Ma,即早古新世和晚古新世之间;第2幕发生在35～36Ma,即始新世和渐新世之间;第3幕发生在10Ma,即中中新世和晚中新世之间;第4幕发生在早更新世和中更新世之间。由此可见,所谓四川运动就是喜马拉雅运动。这次运动为川西前陆盆地油气运移富集创造了条件,并是川西前陆盆地储层裂缝形成的主要原因。川西前陆盆地大多数气藏是在“四川运动”期间形成的。

SICHUAN MOVEMENT IN WEST SICHUAN FORELAND BASIN AND ITS RELATON TO OIL AND GAS

The measurement and computer modelling of apatite fission tracks in Western Sichuanforeland basin and Longmenshan Region offer new information for the recognition of "Sichuan Movement". The "Sichuan Movement" has four episodes. The first one took place in60 Ma (Early Paleocene-Late Paleocene),the second one took place in 35-36 Ma (EoceneOligocene),the third episode happened in 10 Ma (Middle-Late Miocene),and the fourth onein Early-Late Pleistocene. It could be seen from the above mentioned that the so-called"Sichuan Movement"is acturally the Himalayan movement. This movement provided available condition for hydrocarbon migration and accumulation,and it is also the main cause resulting in effective fractures in the basin. Most of the gas pools in the basin were formed during this period.