Morphology of Khorgo Volcano Crater in the Khangai Mountains in Central Mongolia

Altanbold Enkhbold,Byambabayar Ganbold,Sanchir Dorjgochoo,Ulambadrakh Khukhuudei

doi:10.5564/pmas.v60i1.1333

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https://doi.org/10.5564/pmas.v60i1.1333

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Abstract

Cenozoic basalt, which is widespread in Mongolia, has been attracting the attention of Central Asian researchers since the beginning of the last century. This study identified the geomorphological shape of the Khorgo volcano. The main purpose of the study is to determine the origin and morphological form of Khorgo volcano, a key representative of Cenozoic volcanism. In general, there are several types of morphological forms associated with lava overflow, and it is important to determine which types are the most common and also to establish a link between them. Geomorphological studies in this area have not been conducted in Mongolia. Spatial improvement and morphometric methods satellite imagery had identified Khorgo volcanic faults.Khangai magmatism had thinned its crust to 45 km during the Tariat-Chuluut volcanic activity. It can be concluded that this was due to the thinning of the continental crust in the Khangai Mountains because of mantle plume. During this time, tectonic faults formed were formed, which had broken through the earth's crust. Part of this fault was formed in the vicinity of Khorgo Mountain from northwest to southeast, and lava flowed with the basic composition, which led to the formation of the current morphological form of Khorgo volcano. The lava flow was less than 45% silica and potassium-dominated, which blocked the Suman River valley and formed the present-day Terkhiin Tsagaan Lake. The morphometric analysis compared the morphology of a typical volcano, which showed that the mouth of the crater of the Khorgo volcano has a slope slanting about 45 degrees, it is about 100 meters in depth, with a diameter of about 500 meters. By comparing the basalt composition of the Khorgo volcano and its morphometric characteristics with other standard volcanoes, it has been determined that it is in the form of a lava dome.

Highlights

The Khangai Region in Central Mongolia is a mountainous area covering about 200,000 sq. km. with numerous peaks over 3,500 meters and is one of the important 'domed' structure within the basement blocks of Mongolia [1].The Khangai region consists mainly of intensively deformed Carboniferous-Devonian and minor Permian-Triassic sedimentary rocks, which were deposited on basement blocks and intruded by huge bodies of granite and granodiorite plutons [2] appertaining to Late Paleozoic to Early Mesozoic periods
It is possible to determine the geomorphological shape of volcanoes in Mongolia according to their origin. This significance of this study becomes more important as it determines the geomorphological shape of the Khorgo volcano in relation to its origin
The location of the volcanic crater around Tariat is almost in a straight line, which is directly related to tectonic faults

Summary

Introduction

The Khangai Region in Central Mongolia is a mountainous area covering about 200,000 sq. km. with numerous peaks over 3,500 meters and is one of the important 'domed' structure within the basement blocks of Mongolia [1].The Khangai region consists mainly of intensively deformed Carboniferous-Devonian and minor Permian-Triassic sedimentary rocks, which were deposited on basement blocks and intruded by huge bodies of granite and granodiorite plutons [2] appertaining to Late Paleozoic to Early Mesozoic periods. Numerous high potassium alkaline basaltic provinces of the Late Cenozoic Era, which are covered by unconsolidated Quaternary sediments, are distributed throughout the Khangai Region. The proof is that lava overflow filled some of the river basins during the earlier stage of Quaternary Era and basalt’s rocky sheets belong to the Miocene and Pliocene’s earlier periods that resulted in the Khangai depression, and the dumping outer surface proves that basalt of this volcano belongs to the Pliocene’s late period to the earlier period of the Quaternary Era. The extinction period of volcano with its outer surface creation is estimated by comparing it with younger terraces [18,19]

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