关键词: 准噶尔盆地, 西北缘, 哈拉阿拉特山, 前陆冲断带, 双重构造, 断层转折褶皱, 油气勘探

Abstract: The foreland thrust belt in northwestern margin of Junggar basin is a large-scale imbricated thrust system developed since Late Carboniferous. The Hala'alat mountain, the eastern segment of the leading thrust belt, is composed of four elements such as Xiemisitai monocline, the Heshituologai basin, the Hala'alat imbricated zone and the western slope of Mahu sag. The Hala'alat thrust system can be subdivided into the upper and lower units of distinct deformation styles bounded by slippage surface of Paleozoic strata. There exist three or four imbricated thrust zones in the upper unit, each of which pinches out the slippage surface. In the lower one, there could be ten more superimposed structures consisted of Paleozoic fault blocks. The Hala'alat thrust belt is about 61 km wide and shortened by 53 km with scalage of 46%.t. The structural deformation originated at the Late Triassic and ceased at the Early Cretaceous. In the paraautochthon of the lower block in the leading thrust occurred a series of fault-bend folds and superimposed structures, which are the most potential targets for oil-gas exploration in the near future in the northwestern margin of Junggar basin. It is concluded that the targets should be the major domains for discovering another "Karamay field" beneath existing Karamay oilfield.

Key words: Junggar basin, northwestern margin, Hala'alat mountain, foreland thrust belt, superimposed structure, fault-bend fold, petroleum exploration