大别山超高压变质带深部电性结构及其动力学意义初步研究  

A preliminary study on electrical structure and dynamics of the ultra-high pressure metamorphic belt beneath the Dabie Mountains

作　　者：肖骑彬[1] 赵国泽[1] 詹艳[1] 陈小斌[1] 汤吉[1] 王继军[1] 邓前辉[1] 

机构地区：[1]中国地震局地质研究所,北京100029

出　　处：《地球物理学报》2007年第3期812-822,共11页Chinese Journal of Geophysics

基　　金：国家自然科学基金重点项目(40534023)资助

摘　　要：通过在大别造山带东部横穿超高压变质带的一条NNE向剖面大地电磁测深资料的分析解释,获得了关于沿剖面的地壳上地幔二维电性结构,显示北淮阳与大别地块是电性差异显著的构造单元,它们之间的界面与晓天—磨子潭断裂对应;晓天—磨子潭断裂倾向北,在中上地壳层位出现错动解耦现象;从地表向深处可划分出4个主要电性层:地表风化层、中上地壳高阻层、壳内相对高导层以及上地幔层;大别地块内中、上地壳层位以高阻层为主,与高压-超高压变质岩分布区对应,高阻层最厚处在岳西—英山之间;在大别地块内,推测存在燕山期花岗质岩浆活动的通道,它们造成了超高压变质岩的进一步抬升,同时影响了大别地块内存在的壳内相对高导层的分布,壳内相对高导层在层位上相差较大.Magnetotelluric data along a profile in the East Dabie Mountains has been collected along the profile across the ultra-high pressure metamorphic belt of NNE direction. According to the two-dimensional electrical structure of crust-upper mantle of the Dabie orogen, the North Huaiyang tectonic belt and Dabie block are different tectonic units in electrical structure. They are separated by the Xiaotian-Mozitan fault, which dips north and shows decoupling at the mid-upper crust level. Four electrical layers can be determined from surface to depth, which are the surficial weathering layer, the mid-upper crust high resistivity layer, the inner-crust relatively high conductive layer and the mantle layer. In the Dabie block, the mid-upper crust is mainly of high resistivity, corresponding to the distribution area of high-ultrahigh pressure metamorphic rock, its thickest place is between Yuexi and Yingshan. In the Dabie block, there maybe exist channels of granitic magma activity of the Yanshan Period, which make further uplift of the ultra-high pressure metamorphic rocks and affect the distribution of inner-crust high conductive layers and cause great difference in depth of the high conductive layer.

关 键 词：超高压变质带 深部电性结构 动力学 大地电磁测深 大别造山带 

分 类 号：P631[天文地球—地质矿产勘探]