Tectonic geomorphology of the lake depressions in the Mongolian Altai Mountains, Western Mongolia

Altanbold Enkhbold^1,2Ulambadrakh Khukhuudei^3,4*Yeong Bae Seong⁵Gansukh Yadamsuren⁶Batzorig Batbold²Davaadorj Davaasuren²Altanbold Enkhbold⁷Ser-Od Tsedevdorj⁸Daariimaa Badarch⁹Byambabayar Ganbold²

• ¹National University of Mongolia, Sükhbaatar, Mongolia
• ²Laboratory of Geopedology, Department of Geography, School of Arts and Sciences, National University of Mongolia, Ulaanbaatar 210646, Mongolia, Ulaanbaatar, Mongolia
• ³Research Center of Geology and Mineral Resources, School of Arts and Sciences, National University of Mongolia, Ulaanbaatar 210646, Mongolia, Ulaanbaatar, Mongolia
• ⁴Center for Global Tectonics, School of Earth Sciences and State Key Laboratory for Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China, Wuhan, China
• ⁵Department of Geography Education, Korea University, Seoul 02841, Republic of Korea, Seoul, Republic of Korea
• ⁶Department of Ecology, Agroecology School, Mongolian University of Life Sciences, Ulaanbaatar 17024, Mongolia, Ulaanbaatar, Mongolia
• ⁷Division of Natural System, Institute of Nature and Environmental Technology, Kanazawa University, Japan, Kanazawa, Japan
• ⁸Department of Geography, School of Mathematics and Natural Sciences, Mongolian National University of Education, Ulaanbaatar, 14191, Mongolia, Ulaanbaatar, Mongolia
• ⁹Department of Geology-Geophysics, School of Arts and Sciences, National University of Mongolia, Ulaanbaatar 210646, Mongolia, Ulaanbaatar, Mongolia

This study explores the tectonic geomorphology of lake depressions in the Mongolian Altai Mountains (MAM), focusing on three prominent lakes: Tolbo, Achit, and Uureg. These lakes are situated within tectonically active zones in the westernmost part of Mongolia, providing valuable insights into the interplay between geological processes and geomorphological evolution. The study investigates the structural characteristics and faults influencing lake depressions, utilizing satellite imagery, morphometric analysis, and geomorphological criteria interpretation. The morphometric analysis reveals significantly high HI (%) values for the Uureg, Achit, and Tolbo lake depressions, suggesting active tectonic movements in these regions. Additionally, the Smf, Bs, RSl, and Re indices support the evidence of ongoing tectonic processes. Since the northern MAM are located within a transpressional stress regime, the associated basins are expected to reflect this tectonic setting. Accordingly, all intermontane basins in the region are characterized as half-ramp, remnant low, or ramp basins. Each depression is shaped by different fault regimes, including thrust, strike-slip, and tilted thrust faults. These depressions are controlled by neotectonic processes associated with the Indian-Eurasian plate collision. Their dynamic nature underscores their significance as key tectonic features in the MAM. This case study deepens our understanding of the dynamic interplay between tectonics and lake depression formation in seismically active regions. It contributes valuable insights into the geomorphological evolution of mountainous landscapes.