Mongolian Geoscientist <p>The Mongolian Geoscientist is published by the <a title="MUST" href="" target="_blank" rel="noopener">Mongolian University of Science and Technology </a>with support from&nbsp;<a title="Mongolian Geological Society" href="" target="_blank" rel="noopener">The Geological Society of Mongolia</a>.</p> <p><strong>The Mongolian Geoscientist is included on <a title="Google Scholar" href="" target="_blank" rel="noopener">Google Scholar</a>, <a title="Dimensions" href="" target="_blank" rel="noopener">Dimensions,</a>&nbsp;<a title="DOAJ" href="" target="_blank" rel="noopener">DOAJ</a> and <a title="CNKI" href="" target="_blank" rel="noopener">CNKI</a></strong></p> Mongolian University of Science and Technology en-US Mongolian Geoscientist 2220-0622 <p>Copyright on any research article in the <strong>Mongolian Geoscientist</strong> is retained by the author(s).</p> <p>The authors grant the <strong>Mongolian Geoscientist</strong> a license to publish the article and identify itself as the original publisher.</p> <p><a href="" rel="license"><img src="" alt="Creative Commons Licence"></a><br>Articles in the <strong>Mongolian Geoscientist</strong> are Open Access articles published&nbsp;under a <a href="" rel="license">Creative Commons Attribution 4.0 International License</a> CC BY.</p> <p>This license permits use, distribution and reproduction in any medium, provided the original work is properly cited.</p> <p>&nbsp;</p> Stratigraphy of the Khuvsgul Group, Mongolia <p>The Khuvsgul Group (Khuvsgul Province, Mongolia) is a Late Neoproterozoic to Cambrian carbonate-dominated succession that includes minor glacial diamictite and one of the largest known ore-grade phosphate deposits in the world. These strata, which have experienced low-grade metamorphism, are exposed in the Khoridol-Saridag Range on the western margin of Lake Khuvsgul. Since 2017, new geologic mapping and field studies have been conducted in the Khuvsgul region. During the course of this work, it has become necessary to restructure the stratigraphic framework of the Khuvsgul Group in order to better facilitate geologic mapping, stratigraphic observations, and regional correlations. We have divided the lower Khuvsgul Group into four distinct formations spanning the Cryogenian and Ediacaran, each of which encompass strata associated with the Sturtian glaciation, Cryogenian non-glacial interlude, Marinoan glaciation, and basal Ediacaran transgression respectively. The phosphorites of the Khuvsgul Group are now included within a new distinct formation, while the overlying Cambrian carbonates and siliciclastic rocks have been further subdivided to streamline mapping and correlation efforts. The stratigraphic framework outlined below will simplify identification and differentiation of Khuvsgul Group rocks in the field and provide a foundation for the interpretation of Khuvsgul Group strata within the context of the changing climatic, tectonic, and paleoenvironmental conditions of the late Neoproterozoic and early Cambrian.</p> Eliel Anttila Francis Macdonald Uyanga Bold Copyright (c) 2021 Eliel Anttila, Francis Macdonald, Uyanga Bold 2021-06-23 2021-06-23 26 52 2 15 10.5564/mgs.v26i52.1516 Metamorphic rocks from the north-eastern part of the Ereendavaa terrane (Eastern Mongolia) : <p>In this paper, we have conducted geochronological and geochemical studies on the metamorphic rocks of the Khaychingol and Ereendavaa Formations in the Mogoitiin Gol, Khaychin Gol and Emgentiin Bulag areas from the Ereendavaa terrane and these rocks have been considered to be Precambrian in age. However, new LA–ICP–MS zircon U–Pb dating results indicate that the protolith of the studied metamorphic rocks was formed in two stages: 1) during ~ 296 - 285 Ma, the protolith of mafic, felsic and black schists formed; 2) during ~276 - 271 Ma, the protolith of gneiss and psammitic schists began to deposit. The Early Permian bimodal association composed of low-K basalt and comagmatic high-Na, low-K dacite with high-K calc-alkaline rhyolite, represent protolith of the mafic and felsic schists which were formed in back-arc basin environment. The Middle Permian gneiss, and psammitic schists with sedimentary protolith have geochemical signatures of island arc rocks, such as enrichment of LILE relative to HFSE, and markedly negative Nb, Ta and Ti anomalies, suggesting that they were formed in a continental arc environment. Considering a close spatial relationship of the Ereendavaa terrane with the Mongol-Okhotsk Belt in the north-west, we propose that accompanied with the emplacement of arc magmatic rocks, the arc rifting occurred and formed the Early Permian bimodal volcanic rocks. In the Late Permian, after the formation of the back-arc basin, deposition of the immature deposits as wacke, arkose and litharenite dominated sediments in a continental arc environment started.</p> Tserendash Narantsetseg Yuan Chao Wang Tao Ren Zhongyuan Li Pengfei Zhang Le Guo Lei Tong Ying Demberel Orolmaa Altanbaatar Battushig Orosoo Baatarchuluun Tuya Idermunkh Jargalsaikhan Tumendelger Copyright (c) 2021 Tserendash Narantsetseg, Yuan Chao, Wang Tao, Ren Zhongyuan, Li Pengfei, Zhang Le, Guo Lei, Tong Ying, Demberel Orolmaa, Altanbaatar Battushig, Orosoo Baatarchuluun, Tuya Idermunkh, Jargalsaikhan Tumendelger 2021-06-23 2021-06-23 26 52 16 45 10.5564/mgs.v26i52.1079 The 2021 M<sub>w</sub> 6.7 Khankh earthquake in the Khuvsgul rift, Mongolia <p>A M<sub>w</sub> 6.7 occurred at Lake Khuvsgul in northwestern Mongolia at 05:32:56 AM Ulaanbaatar time on the 12<sup>th</sup> of January 2021. The epicenter of the event was offshore south of the Doloon Uul peninsula around 30 km SSW of Khankh village. Shaking was felt within most of central and western Mongolia, including the capital city Ulaanbaatar ~600 km from the epicenter. The earthquake appears to have ruptured the Khuvsgul fault along the western coast of Lake Khuvsgul. The earthquake is the largest in Mongolia since the M<sub>w</sub> 6.3 Busiin Gol earthquake in 1991. Our research team from the Institute of Astronomy and Geophysics, Mongolian Academy of Sciences visited the epicenter area for 5 days soon after the earthquake and installed four broad-band seismic stations and searched the area for geological evidence of the earthquake. The location, azimuth, dip and depth of this earthquake defined by moment tensor solutions calculated by the international seismological centers and analysis of InSAR interferograms and field observations. The projected intersections of the east-dipping nodal planes with the surface for solutions of the international seismological centers and researchers correlate relatively well with the mapped strike and location of the old tectonic scarp of the Khuvsgul fault although we have not discovered any primary co-seismic surface rupture. The InSAR interferogram demonstrates the sharp discontinuity and fringes in the area between the Western Range and Doloon Uul peninsula which implies surface deformation. Aftershocks that have continued during the three months subsequent to the earthquake define overall strike of the mainshock rupture.</p> Davaasambuu Battogtokh Amgalan Bayasgalan Kang Wang Davaasuren Ganzorig Jargalsaikhan Bayaraa Copyright (c) 2021 Davaasambuu Battogtokh, Amgalan Bayasgalan, Kang Wang, Davaasuren Ganzorig, Jargalsaikhan Bayaraa 2021-06-23 2021-06-23 26 52 46 61 10.5564/mgs.v26i52.1361 Gobi Altai, Khangai and Khentii Mountains mapped by a mixed-method cartographic approach for comparative geophysical analysis <p>Geologic and geophysical mapping has been so far limited to the traditional single-method GIS-based mapping. A new approach combining integrated analysis of data on geology, gravity, topography and geomorphology is presented for regional characterization of the geophysical setting in Mongolia: the Gobi Altai Mountains, the Khangai Mountains and Khentii Mountains with surrounding areas. Nine new maps have been produced from the high-resolution datasets: GEBCO, gravity raster, USGS geological data and SRTM-90 DEM geomorphological grid. Methodology includes three tools for cartographic data visualization: i) Generic Mapping Tools (GMT), ii) R programming language (‘raster’ and ‘tmap’ libraries); iii) QGIS. The results demonstrated strong agreement between the estimated values in gravity and topography grids, distribution of geological units and provinces over the country and geomorphological landforms with respect to the mountain ranges: Altai, Khangai and Khentii Mountains. The highest values in the gravity anomalies correspond to the mountain ranges in the Altai Mountains and Khangai Mountains (&lt;80 mGal); high values correspond to the Khentii Mountains (20–60 mGal). Contrariwise, the basins of the Uvs Nuur and Khyargas Nuur show negative values (&lt;-80 mGal). The NE- to NNE-oriented faulting and rift basins are clearly visible in the geophysical grids and geologic maps. The geomorphometric analysis performed based on the SRTM-90 DEM using R scripting demonstrated (1) slope, (2) aspect, (3) hillshade and (4) elevation models of Mongolia supported by histograms of data distribution and frequency. The study contributed to the cartographic methods and regional geological studies of Mongolia.</p> Polina Lemenkova Copyright (c) 2021 Polina Lemenkova 2021-06-23 2021-06-23 26 52 62 79 10.5564/mgs.v26i52.1512 The geophysical signature of Oyut deposits, Oyu Tolgoi, Mongolia <p>The well-known Oyu Tolgoi Cu-Au group deposits can be divided into three main deposits: Hugo Dummett deposit (Hugo North and Hugo South), Oyut deposits (South Oyu, Southwest Oyu and Central Oyu), and Heruga deposit in the south. These deposits sit along 26 km long, north-northeast trending belt termed as the Oyu Tolgoi trend. This paper reviews investigations on geophysical signatures of the South Oyu, Southwest Oyu and Central Oyu deposits and compares geophysical models of the mineral deposits with their lithology, alteration, mineralization, and structures. A variety of datasets including induced polarization, ground magnetic, gravity survey are used in the study and generated inversion products of ground magnetic and gravity data with integrated interpretation. Typical responses from the Oyut deposits are: up to 0.1 mGal positive gravity anomaly above background, 100–200 nT low or high magnetic anomaly compared to background depending on the geological situations, and from 12 mV/V to 30 mV/V chargeability anomalies and low resistivity signatures from 100 ohm.m to 400 ohm.m. The interpreted geological-geophysical models of porphyry Cu-Au deposits presents in this study have emphasis on integrated interpretation of geophysical techniques, and inversions of gravity and magnetic data in gold rich porphyry copper system.</p> Erdene Batbaatar Munkhjargal Todbileg Otgonbayar Sansar Baatar Bataa Copyright (c) 2021 Erdene Batbaatar, Munkhjargal Todbileg, Otgonbayar Sansar, Baatar Bataa 2021-06-23 2021-06-23 26 52 80 96 10.5564/mgs.v26i52.1323 Editorial <p>No Abstract in English</p> Bayaraa Batkhishig Copyright (c) 2021 Bayaraa Batkhishig 2021-06-23 2021-06-23 26 52 1 1 10.5564/mgs.v51i0.1461