准噶尔盆地及外围盆地的侏罗系与盆地基底问题

ON THE JURASSIC AND BASEMENT OF JUNGGAR BASIN AND ITS PERIPHERAL BASIN

准噶尔盆地及其１５个外围盆地的侏罗系是一套具有一定含油气远景的层系。中下侏罗统为烃源岩和储层，上统为储层及区域盖层。根据基底性质可将它们分为以前震旦系老克拉通为基底的中间地块盆地和以海西期新克拉通为基底的山间盆地两大类。前者多为继承性盆地，含油层系多、远景好，后者多为残余盆地，含油气情况复杂。准噶尔盆地下石炭统均为未变质的海陆交互相沉积，泥盆系除个别地区外，也均未变质。因此这套地层应属盆地盖层，而不是盆地的基底部分。

The Jurassic in Junggar besin and its fifteen peripheral besins is a contariation of sequence with fair hydrocarbon potential: Middle and Lower Jurassic are considered to be the source rock and reservoir, and Upper Jurassic as the reservoir and regional caprock. According to the nature of basement, these besins can be divided into two categories:intermediate massif basin, with old craton of the Presinian period as basement, and intramontane basin, with new craton of the Hetcynian peried as besement. The former are mostly an inherited basin, with various oil-bearing sequences and better oil potential; and the latter are mostly a residual basin, with complex hydrocarbon condition.Lower Carboniferous in Junggar basin is nonmetamorphic paralic facies, and Devonian is also nonmetamorphic except in very few areas. As a results. this sequence should be considered as the caprock rather than as the basement.