Abstract

Magnetotelluric soundings (MTS) are carried out in a broad frequency range from 10⁴ to 10^–3 Hz at a total of fifty-five sounding sites spaced about 5 km apart along the profile Dal’nerechensk–Roshchino–Plastun across the strike of the Sikhote Alin Orogenic Belt (SAOB). Based on the results of data interpretation, the crust and upper mantle geoelectric section is constructed down to a depth of 150 km. The section shows the crust of variable thickness between 20 and 40 km with a resistivity higher than 1000 Ohm m, which consists of different-resistivity blocks bordered by subvertical and inclined low-resistivity zones, from tens to a few hundreds of Ohm m. Three abnormal-resistivity zones are revealed in the crust and upper mantle. The upper mantle structure is nonuniform. Beneath the western and eastern parts of the SAOB, the lowest resistivity values are observed at 40–80 km depths. A high-resistivity zone of 300–500 Ohm m, stretching in the westerly direction from the coast beneath the Khanka superterrane, is identified in the 80–150 km depth range. This area is treated as remnants of the plate of an ancient subduction zone; two low-resistivity canals are distinguished here, which are associated with a slab-window. The results obtained for the northern and southern parts of the SAOB are compared and their similarities and dissimilarities are ascertained.

中文翻译：

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从大地电磁测深资料看，沿着达拉涅琴斯克-罗什基诺-普拉斯顿剖面的锡克特山脉南部的地壳和上地幔结构

摘要

大地电磁测深（MTS）在10 ⁴至10 ^–3的较宽频率范围内进行沿着Sikhote Alin造山带（SAOB）的走向沿Dal'nerechensk–Roshchino–Plastun剖面的总共55个测深点的Hz间隔约5 km。根据数据解释的结果，构造地壳和上地幔地电断面的深度一直到150 km。该部分显示了厚度在20至40 km之间的地壳，其电阻率高于1000 Ohm m，该地壳由不同的电阻率块组成，这些块体的边界为垂直的和倾斜的低电阻率区域，范围从几十到几百Ohm m。在地壳和上地幔中发现了三个异常电阻率区。上地幔结构不均匀。在SAOB的西部和东部部分，在40–80 km深度处观察到最低的电阻率值。300-500 Ohm m的高阻区，在80–150 km的深度范围内，从汉卡超地层下方的海岸向西延伸。该区域被视为古代俯冲带板块的残余；这里区分了两个低电阻率的渠道，它们与平板窗相关联。比较了SAOB北部和南部获得的结果，并确定了它们的异同。