塔里木北部地区北北西向构造变换带特征及对石油勘探的启示

FEATURES OF NNW-STRIKING STRUCTURAL TRANSFER ZONE IN NORTH TARIM AND ITS INSPIRATION FOR OIL EXPLORATION

库车油气系统发育近东西方向的线性构造 ,同时在横向上存在起调节作用的构造变换带 ,如塔拉克—喀拉玉尔衮一线即为一复杂的大型构造变换带。该构造带总体上为北北西向 ,由多个斜列的北西向背斜带组成 ,对盆地的构造样式沿构造线走向发生的变化起着重要的调节作用。分析认为西秋里塔格构造带是在早期北西向构造基础之上 ,受晚第三纪时期前陆地区由北向南的挤压作用形成的构造变换带 ,盐岩层及其相应的构造变形对该变换带的形成有重要影响。西秋里塔格构造变换带有利于石油运聚成藏 ,其南部有古构造背景、晚期无大规模气侵的圈闭是寻找石油的有利方向。

The tectonic line in north Tarim was nearly W-E trending, with a series of narrow, linear to curvilinear anticlines being well developed, which was rich in oil-gas and named the Kuqa petroliferous system covering the Kuqa Depression and part of the North Tarim Rise. And there were the NNW-striking structures, namely, the structural transfer zones which accommodated the displacement across the main structures. The Xiqiulitage-Shengli structural transfer zone, separated the Wushi Depression and the Wensu Rise in the west from the Kuqa Depression and the North Tarim Rise in the east, respectively, was the largest-scale and most important one. The structural transfer zone, with a complicated inner textures, was composed of some en echelon anticlinal belts. It created in Neogene in a foreland area, by a southward compressive stress field, and the earlier NW-striking structure in an age of Hercynian-Indosinian also played an important role in its creation. The tectonic style of the Xiqiulitage-Shengli structural transfer zone was controlled by the basement structures, the asymmetrical thrusting and the salt structure developing. Occurring of the structural transfer zones was favorable for oil migration and accumulation. In southern part of the studied area, the target for oil exploration might be the traps which had a paleostructural background and not influenced by later large-scale gas cutting.