Deep Structure of the Lithosphere in the Central Tien Shan along the Son-Kul Magnetotelluric Sounding Profile

A K Rybin,K S Nepeina,V E Matiukov,E A Bataleva,Yu A Morozov

doi:10.1134/s1028334x21020161

A K Rybin, K S Nepeina + Show 3 more

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https://doi.org/10.1134/s1028334x21020161

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Abstract

New results of a detailed study of the deep structure of the Central Tien Shan along the Son-Kul magnetotelluric (MT) profile crossing the Son-Kul Lake are reported. Based on the results of magnetotelluric data modeling, the regional and local geoelectric anomalies in the lithosphere are studied and their quantitative characteristics are given. Geological interpretation of the geoelectric cross-section was carried out, which supported the existing ideas about the block–hierarchical structure of the upper part of the Earth’s crust. This corresponds to the tectonophysical concepts of the sequential inserted subordination of large and smaller elements of the zone–block structure consisting of stable blocks and limiting mobile zones, which are distinguished by the high dislocation of the geological substrate. The integral pattern of the distribution and morphology of zones of high electrical conductivity in this segment of the Central Tien Shan crust may reflect discretely localized palm tree–type structures associated with the evolution of transgressive suture zones of localized deformation during the Hercynian and Alpine tectogenesis.

Highlights

Well [3, 5]
A comparative analysis of geological and geophysical data on key elements of the geoelectric model developed along the Son-Kul magnetotelluric sounding (MTS) profile was carried out
Due to the significantly more detailed and accurate MTS data, the boundaries of the Issyk-Kul microcontinent corresponding to modern tectonic concepts were obtained in the conductive structures of the constructed geoelectric cross-section at the stage of qualitative interpretation and the first quantitative estimates

Summary

Introduction

Well [3, 5]. The magnetotelluric sounding performed in this study can provide the prerequisites for clarifying the answer to the following question: are the geoelectric anomalies discovered associated with deep tectonic faults or with fracturing of the Son-Kul granitoid massif itself. This largest structural boundary between the uneven-aged formations of the Northern and Central Tien Shan practically does not manifest itself in the neotectonic structure, while being well reflected in the results of deep electromagnetic studies. Another structural element that may appear in the geoelectric model is the so-called Kyrgyz–Terskey oceanic suture zone [6], which is observed from the western part of the Kyrgyz Range to the southeast, to the area of Lake Son-Kul and to the east, to the upper reaches of the Naryn River. Son-Kul profile, which was laid across the strike of the major tectonic structures of the Central Tien Shan on the territory of the Son-Kul Basin, by the Research Station of the Russian Academy of Sciences in Bishkek, with the support of the Russian Science Foundation, project no. 17-16-10059 (Fig. 1)

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