摘要
青藏高原为近代构造与地震均十分活动的地区,并有独特的地壳、上地幔结构与物质组成.为了探讨本区南部航磁异常及其与深部构造的关系,对航磁资料进行了处理和分析.航磁比例尺为1:20万,精度为土5伽玛,飞行高度平均三千米.研究区域包括冈底斯—念青唐府古拉褶皱系,喜马拉雅褶皱系以及这两个褶皱系的分界线雅鲁藏布江深大断裂带,我们在此也称之为雅鲁藏布江碰撞带,文中将对此进行论述.本区的磁异常要是由岩浆岩体所引起.酸性岩的磁化强度一般在300×10-6CGSM以下.超基性岩约为(1500～4000)×10-6CGSM.两者所引起的磁异常具有一定的差别.本区磁倾角约为44°,并且多数异常的走向近东西向,使△T异常比较复杂.
Abstract
Chinghai-Tibet Plateau (青藏高原) is such a region where the tecto-genesis and earthquake are in common occurrence and it comprises its special structure in both the earth crust and the upper mantle. In order to make clear the relationship between the aeromagnetic anomalies of the southern part of this area and the structure at depth, process and analysis have been made for the aeromagnetic data obtained. The scale of the airborne magnetic survey is 1:2×105, its precision is ±5 r and the average flight height is 3 kms.The area under research includes: Gangdise Shan-Nianqing Tanglha Ra Fold Syst tem (冈底斯-念青唐古拉褶皱系) , the Himalayas Fold System (喜马拉雅褶皱系) and the divide line of these two systems - the Tsangpo River Deep Rift Zone (also called Tsangpo River Collison Zone) which will be discussed in the ensuing paragraph.The magnetic anomaly of this district is caused mainly by the mag-matic rock. The magnetization of the acid rock is less than 300×10-6C. G.S.M.. For the ultra-basic rocks, its magnetization is about (1500~ 4000) × 10-6 C.G.S.M.. The anomalies caused by the acid rocks are quite different from those caused by the ultra-basic rocks. The regional magnetic dip is about 44° Most of the strikes of the anomalies are nearly E-W, so that it made the △T anomalies rather complicated.
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