塔里木盆地东北部磁性基底深度及构造属性  

Depth and Tectonic Properties of Magnetic Basement in Northeastern Tarim Basin

作　　者：匡星涛 宁方馨 肖梦楚 朱晓颖 徐曦 Kuang Xingtao;Ning Fangxin;Xiao Mengchu;Zhu Xiaoying;Xu Xi(China Aero Geophysical Survey and Remote Sensing Center for Natural Resources,Beijing 100083,China)

机构地区：[1]中国自然资源航空物探遥感中心,北京100083

出　　处：《地球科学》2023年第4期1351-1365,共15页Earth Science

基　　金：中国地质调查局项目(Nos.DD20160065,DD20190025).

摘　　要：为了探讨塔里木盆地东北部磁性基底深度、性质及其对构造属性的指示意义,基于最新的高精度航磁数据,利用剖面切线法计算了塔里木盆地东北部磁性体最小埋深,并绘制了磁性基底深度图.结果显示,大部分地区的磁性基底深度与勘探地震的沉积盖层底界深度相差不大,表明切线法计算结果具有很高的可信度.但是在塔东隆起北缘,磁性基底起伏较大,与沉积盖层底界深度差异明显.在分析磁性基底深度图的基础上,结合高精度布格重力异常以及地震解释剖面,探讨了塔东隆起和孔雀河斜坡的构造属性.研究认为,塔东隆起北缘显著的长波磁异常梯度带和较低的重力值,剧烈变化的磁性基底深度,以及大量钻遇的古元古代变质花岗岩,均指示塔东隆起可能是塔里木盆地东北部最重要的前寒武纪构造边界.孔雀河斜坡重磁异常呈现明显的负相关性,基于磁性基底、南华系-震旦系沉积厚度等与重磁异常的空间结构关系,以及岩石磁性特征等,认为新元古代的裂谷作用可能降低了基底磁性,而北部凹陷中南部未受裂谷作用影响,依然保留了强磁性特征.In order to explore the depth and properties of magnetic basement in northeastern Tarim basin and its indication for tectonic attributes,based on the latest high-precision aeromagnetic data,the minimum buried depth of magnetic body in northeastern Tarim basin was calculated by using section tangent method,and the magnetic basement depth map was drawn.The results show that the depth of magnetic basement in most areas of northeastern Tarim basin is approximate to the depth of bottom boundary of sedimentary cover in seismic exploration,indicating that the calculation results of tangent method have high reliability.However,in the northern edge of Tadong uplift,the magnetic basement fluctuates greatly,and the depth is obviously different from that of sedimentary cover layer.Based on the analysis of the magnetic basement depth map,combining the high-precision Bouguer gravity anomaly and seismic interpretation profile,the tectonic attributes of the Tadong uplift and Kongquehe slope are interpreted.The obviously long-wave magnetic anomaly gradient zone,the low gravity,the highly variable magnetic basement depth,combining a large number of the Paleoproterozoic metamorphic granite samples in borehole,indicate that Tadong uplift may be the most important Precambrian structural boundary.The gravity and magnetic anomalies in Kongquehe slope show obviously negative correlation.Based on the spatial structure relations of magnetic basement,the Nanhua-Sinian sedimentary thickness and gravity-magnetic anomalies,and the magnetic characteristics of the rock,etc.,in this study it suggests that the Neoproterozoic rift event may reduce the magnetism of the basement,on the contrary,the crust of the central and southern region of northern depression which was not affected by the rifting,still retains the strong magnetic characteristics.

关 键 词：航磁异常 磁性基底 塔东隆起 构造边界 孔雀河斜坡 新元古代裂谷 地球物理学 构造地质学 

分 类 号：P318[天文地球—固体地球物理学]