内蒙古西部银根-额济纳旗盆地航磁异常特征及地质意义

在对银根-额济纳旗（银-额）盆地出露的岩体的磁性特征和航磁异常特征分析的基础上,结合局部重力异常资料和前人在区域地质方面的研究成果,讨论了航磁异常与岩浆岩之间的联系,定量拟合解释了盆地东部地区的一条重磁剖面,进而探讨了岩浆岩的分布规律。研究结果表明,银根-额济纳旗盆地各类岩体磁性分布不均匀,哨马营东南侧的中性岩、银根附近的中性和酸性岩磁性较强,而其它地区出露的岩体的磁性则为弱磁性或无磁性,并且基性岩总体表现为弱磁性;区域磁异常反映了磁性基底的特征,额济纳旗西侧、苏亥图—乌力吉—苏红图一带区域磁力高异常是古元古界深变质岩系的反映,额济纳旗—绿园—特罗西滩—因格井和银根—查干德勒苏一带区域磁力低异常是前二叠系中浅变质岩系的反映;额济纳旗、哨马营北—特罗西滩、苏亥图西—因格井—乌力吉—查干德勒苏一带局部磁力高异常主要由中酸性岩所引起,哨马营—陶勒特—特罗西滩东一带局部磁力高异常主要由中性岩体所引起,绿园—务桃亥—因格井一带局部磁力高异常主要由沉积盖层中磁性物质所引起;区域性大断裂控制着银-额盆地磁性侵入岩的发育。

Features of aeromagnetic anomalies in Yingen-Ejin Banner basin and their geological significance.

On the basis of analyzing features of magnetic characteristics of exposed rock and aeromagnetic anomalies, in combination with the information of local gravity anomalies and previous research achievements in the aspect of regional geology, the authors dis cussed the relationship between the aeromagnetic anomalies and igneous rocks, interpreted a gravity and magnetic section quantitatively, and then probed into the distribution regularity of the igneous rocks in Yingen-Ejin Banner basin. The results show that magnetic properties of all kinds of rocks are unevenly distributed in Yingen-Ejin Banner basin, and the magnetic properties of the intermediate rocks on the southeast side of Shaomaying and the intermediate rocks and acid rocks near Yingen are stronger, the magnetic propertiesof the exposed rocks in other areas are weak or close to zero, and the magnetic properties of the basic rocks are weak. Regional aero- magnetic anomalies reflect the features of the magnetic basement in Yingen-Ejin Banner basin, and the highs correspond to the Lower Proterozoic hypometamorphic rocks in westem Ejin Banner and Suhaitu-Wuliji-Suhongtu area, while the lows correspond to the pre-Permian mid-epimetamorphic rocks in Ejinaqi-Liiyuan-Teluoxitan-Yingejing area and Yingen-Chagandelesu area; the local magnetic highs are caused by the intermediate-acid rocks in Ejin Banner, Shaomayingbei-Teluoxitan and Suhaituxi-Yingejing-Wuh- ji-Chagandelesu areas as well as the intermediate rocks in Shaomaying-Taolete-Teluoxitandong area, and magnetic substance in the sedimentary cover mainly results in local magnetic highs in Liiyuan-Wutaohai-Yingejing area; the regional faults control the distribu- tion of magnetic intrusive rocks in Yingen-Ejin Banner basin.