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地球科学(中国地质大学学报) 2016
准噶尔盆地及邻区地壳磁性特征及其构造意义
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Abstract:
准噶尔地块可分为东、西准噶尔构造区和准噶尔盆地.自古生代以来准噶尔盆地及其周边大规模的火山活动和复杂的构造演化、以及有关准噶尔盆地基底及其与周边的构造关系及其演化,一直存在争议.利用EMAG2岩石圈磁异常模型,采用三维反演技术,对准噶尔及其周边地区的地壳磁化率进行成像,得到了0~60km深度范围之内的磁性结构.反演结果显示:准噶尔盆地腹部地壳磁性结构相对完整;西准噶尔地壳具有与洋壳俯冲相关岛弧环境的磁性结构;东准噶尔和吐哈盆地磁性层较厚且连续,具有古陆基底特征.此外,地壳磁化率异常展示了区域断裂构造及其深部延伸特征,同时显示在覆盖区可能存在隐伏深大断裂带.对该地区岩石圈磁异常成因的定量解释,为深入剖析准噶尔地区岩石圈构造及其与周边构造单元之间的关系提供了有益的资料和参考.
The Junggar block can be divided into east, west Junggar tectonic zones and Junggar basin. Since the Paleozoic, large scale volcanic activity and complex tectonic evolution occurred in the Junggar basin and its surroundings. There have long been controversies on the basement of the Junggar basin, its structure relationship with its surroundings and its evolution. In this paper, we use the EMAG2 lithospheric magnetic anomaly model, together with modern 3D inversion technique, to image the crustal magnetic susceptibility of the Junggar basin and its surroundings, and to obtain the magnetic structure of the 0-60km depth range. The inversion results show that the magnetic structure of the crust in central Junggar basin is relatively complete, the west Junggar crust has a magnetic structure associated with subduction of oceanic crust arc environment, and both the east Junggar and the Turpan basin have thick and continuous magnetic layer with paleocontinental basement features. Moreover, the crustal magnetic susceptibility anomaly shows the regional fault structure and its deep extension features, and existence of concealed deep fault zone in the covered area as well. The quantitative explanation of the origin of the magnetic anomaly in this area provided in this paper can be useful information and reference for the further analysis of the relationship between the lithosphere structure and the surrounding tectonic units in Junggar area