中国华北地区壳内低速高导层(体)成因模式的探讨  

Study on the Origin of Low Velocity and High Conductivity Layer (Body) in North China

作　　者：高平[1] 

机构地区：[1]国家地震局地质研究所

出　　处：《中国地震》1997年第3期223-231,共9页Earthquake Research in China

摘　　要：依据高温高压下华北地区地壳主要岩石的物理性质———波速、电性测定的结果，提出了华北地区低速高导层（体）可能的成因模式以及不同模式的适应范围。认为：碳酸盐岩在深部一定温度、压力和氧逸度条件下碳的析出会导致高导层（体）的出现；深部韧性剪切带组成矿物的定向排列，可使岩石的波速、电性产生各向异性行为，导致低速高导层（体）的产生；绿片岩相和角闪岩相岩石中含水矿物的脱水作用会导致上、中地壳岩石物理力学性质的突变，这可能是该地区低速高导层（体）的主要形成机制；在中、下地壳温压条件下，岩石的熔融和部分熔融也会导致低速高导层（体）的形成；岩石中石英的αβ相转变可形成低速层（体），但不能形成高导层（体）。Based on the high pressure and temperature experimental results of some crustal rocks in North China,several mechanisms of low velocity and high conductivity layer/body(LVL and HCL) in that area have been proposed.Separation of carbon from carbonate rocks under suitable condition of pressure,temperature and oxygen fugacity may lead to the emergence of HCL,melting or partial melting of rocks and preferred orientation of composition minerals due to deformation of rock body in deep ductile shear zone may cause the formation of both LVL and HCL,dehydration of aqueous minerals in the chlorite schist facies and plagioamphibolite facies in the crust may lead to the changes of physical and mechanical properties of rocks in upper and middle crust and may be the main formation mechanisms of LVL and HCL in that area.Under the pressure and temperature condition at the middle crust,the rocks containing more quartz minerals may form LVL but not HCL.

关 键 词：华北地区 低速高导层 成因模式 地壳 物理性质 

分 类 号：P313.3[天文地球—固体地球物理学]