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1980—1981年中法两国的磁大地电流工作者在西藏洛扎一羊八井地区进行了磁大地电流测深。在剖面的北部深20—30公里处发现一壳内低阻层,在南部还发现一个埋藏深度较浅的低阻层。文中阐述了该区的地电特征,对低阻层的成因进行了探讨。认为北部低阻层是由壳内的花岗岩类物质的部分熔融所引起;南部低阻层的情况较复杂,它可能是由一缓倾角的断层摩擦面附近的花岗岩类物质的部分熔融及饱含热水的岩层所引起。根据地下电阻率及温度的分布推测该区可能有一个温度较低的高阻地块向北俯冲到温度较高的低阻地块之下。
Magnetotelluric current surveys were conducted in China and France between 1980 and 1981 by magnetic earth current workers at Luoyang-Yangba-Bajing area. A low-resistivity layer within the shell was found 20-30 km deep north of the profile and a low-resistivity layer with a shallow depth of burial was found in the south. In this paper, the geoelectric characteristics of this area are expounded and the causes of low resistivity layer are discussed. It is concluded that the low-resistivity layer in the north is caused by the partial melting of the granitoids in the crust. The low-resistivity layer in the south is more complicated. It may be caused by the partial melting of the granite near the fault friction surface with a gentle dip and the heat of saturation Water caused by the rock formation. According to the distribution of underground resistivity and temperature, it is presumed that there may be a low-temperature high-resistance block subducting northward to below the high-temperature low-resistance block.