The geological history of the southern part of Mongolia is characterized by the continental accretion and Basin-and-Range style crustal extension, followed by regional-scale compressional folding and faulting. Elongated, east-west trending mountain ranges and intervening basins are therefore widely present in the region. Those structures are dominatly composed of Late Cretaceous to Permian-aged sedimentary sequences, overlain by Quaternary unconsolidated sediments. Mountain ranges between the basins comprise crystalline basement rocks dominated by intermediate to high angle faults that show evidence for both compressional and extensional movement. The most prominent structure in relation to the Ovoot Tolgoi Deposit is the arcuate, east-west-trending, moderately-dipping Nariin Sukhait fault where the Late Permian coal-bearing sequences are exposed.
The Ovoot Tolgoi Coal Mine, which comprises of the Sunset Coalfield in the west and the Sunrise Coalfield in the east, is one of the three operating coal mines in the region of Nariin Sukhait.
The current geological understanding of the deposit has organized the coal seams into a number of Seam Groups including the Seam Nos. 4, 5L, 5U, 6, 7, 8, 9, 10 and 11. Each of the Seam Groups are further divided into a number of sub-layers or known as plies based on parting material within the Seam Groups.
The overall estimated thickness of the coal-bearing sedimentary sequence is 1,370 m with a cumulative th ........
