准噶尔盆地的磁场特征及地质意义

The Magnetic Field Characteristics and Geological Significance of the Junggar Basin

摘要: 本文从地球物理角度对准噶尔盆地航磁异常特征与地质构造进行了分析，确定了盆地的边界及范围，编制了准噶尔盆地变质(磁性)基底埋深图、构造单元划分图，在此基础上对盆地的基底性质及其深度变化特点和构造格局进行了研究，并确定了盆地沉积层厚度。研究表明准噶尔盆地是晚古生代至中、新生代多旋回叠合盆地，基底主要由前泥盆系变质岩系组成，埋深大部分可达3000~15,000 m，沉积盖层为上古生代和中、新生代地层；盆地的发生和发展主要受北西向构造制约，北东向断裂改造了北西向构造。盆地构造面貌呈“四坳三隆”的特点，隆起主要分布于盆地西部和中部偏北地区，范围相对较窄；坳陷分布范围广，沉积厚度大。这些认识为今后在该盆地进行油气勘探提供了参考依据。

Abstract: This paper analyzed aeromagnetic characteristics and geological structure of Junggar basin from the perspective of geophysics, and defined boundaries and scopes of the basin. Based on compilation of magnetic basement depth map and structural zoning map of Junggar Basin, basement structure and properties, depth variation characteristics, structural pattern, and caprock thickness of the basin were studied. The research has shown that the Junggar basin is a polycyclic superposition basin from Late Paleozoic to the Mesozoic and Cenozoic. The basement is mainly composed of the pre-Devonian metamorphic rock series, and most of the buried depth can reach 3000 to 15,000 meters. The caprock is the Upper Paleozoic and Mesozoic and Cenozoic strata. The occurrence and development of the basin are mainly restricted by the northwest-trending structure, and the northeast-trending fault has transformed the northwest structure. The tectonic appearance of the basin is characterized by “four depressions and three uplifts”. The uplifts are mainly distributed in western and north-central areas of the basin, with a relatively narrow range, while the depressions are widely distributed with large deposition thickness. The above cognitions provide references for further oil and gas exploration in this basin.