塔里木盆地中部航磁异常带新解译

横亘于塔里木盆地中部的纬向航磁高ΔTa异常带,一直是探讨盆地及深部基底的物质组成及结构构造的焦点。根据钻井及地震资料综合分析,发现满加尔坳陷中南部上奥陶统内发育大型地震反射异常体,平面上主要由8个地震反射异常体近东西向呈带状展布,与盆地中部航磁高ΔTa异常带相关。从地层发育及地震相特征分析,这些地震反射异常体应为辉绿岩-玄武岩等基性火成岩体,且与航磁ΔTa异常带上的磁力高相对应。异常体具有垂直向下的通道,与断裂及岩浆活动通道有关。盆地中部高航磁异常带为多期构造易活动带,反映了满加尔坳陷震旦纪与中晚奥陶世处于拉张的构造背景。

A new interpretation of the high aeromagnetic anomaly zone in central Tarim Basin

The ΔTa high aeromagnetic anomaly zone lying in the central part of Tarim Basin has been a focus in discussing the composition and structure of Tarim basin and its basement.Based on a comprehensive analysis of borehole and seismic data,the authors have found that there exist large-scale seismic reflection anomaly bodies in Middle-Upper Ordovician strata of Manjiaer depression,which are related closely to the Central High Aeromagnetic Anomalies Zone(CHAAZ) and constituted mainly by eight nearly EW-trending seismic reflection anomaly bodies.The stratigraphic and seismic facies analysis shows that these seismic anomaly bodies should be igneous rocks.The anomaly bodies have vertical downward channels in seismic profiles,which are related to faults and magmatic activity channels.The CHAAZ of the basin is a product of multi episodes tectonic activities,suggesting the development of Manjiaer depression in an extensional tectonic setting in Sinian and Late Ordovician.