10:30 〜 10:55
[T1-04] Geology, sedimentation environment of the
Ovoot khural coal bearing depression, in South Mongolia
「招待講演」
キーワード：Ovoot khural coal、Mongolia
Mongolia has abundant resources of coal, which are distributed mainly in the south and southeastern part, including some deposits in the north and west part of the country. In recent years, the exploration of coal deposits has been intensively carried out, but not much effort has been made to determine the origin, regional regularity of coal distribution as well as relationship between geological condition and coal quality.
The purpose of this study is to clarify geology and sedimentation environment of the Ovoot khural coal bearing depression in order to contribute to the reconstruction of the Mesozoic geologic and geodynamic setting of the Mongolia.
The study area is located at the 1000 km southwest of Ulaanbaatar and 50 km north of the Mongolia-China border, forming latitudinal trending depression which is 40 to 60 km in width and continues more than 200 km. There are five independent coal bearing parts with 16 coal deposits, which are: Bayantes part, contains Elstei, Khurshuut, Khuvd, Gashuu Tolgoi and Khuren tasv deposits; Ovoot Tolgoi part, contains Sunset and Sunrise deposits; Nariin sukhait part contains West Nariin sukhait, Central Nariin sukhait, East Nariin sukhait and Khuren shand deposits; Sumber part contains Central Sumber, Sumber and Biluut deposits and Jargalant part contains Jargalant and South Biluut deposits.
Result of geochemical study indicates that sediments deposited in the Ovoot khural depression is sourced by the weathering and transporting of intermediate and felsic composition magmatic rocks, mainly from dacite, andesite including minor amount of metamorphic, sedimentary and intrusive rocks.
Spider diagrams of trace element composition of sedimentary rocks of the Orgilokhbulag formation, show Nb-depletion and Pb, Mo enrichment, indicating possible origin of magmatic rocks formed under subduction environment and they are intermediate to felsic in composition. The major trace and rare earth element composition of the Orgilokh bulag formation sedimentary rocks, indicate that the source rocks of sediments might have been formed in the active continental margin tectonic setting.
According to provenance model, coal deposition is undertaking with good tissue preservation, in an alternating environment of oxygenic and deoxygenated swamps.
Based on the metamorphic degree, the temperature of peat compression, the amount of volatile, and the depth gradient of temperature, peat was buried and deposited at a depth of 3500-7000 meters. Low sulfur content, low ash content and low volatile content of coal at the various parts of the depression indicates thet the peat deposition is occurred under two stages.
The purpose of this study is to clarify geology and sedimentation environment of the Ovoot khural coal bearing depression in order to contribute to the reconstruction of the Mesozoic geologic and geodynamic setting of the Mongolia.
The study area is located at the 1000 km southwest of Ulaanbaatar and 50 km north of the Mongolia-China border, forming latitudinal trending depression which is 40 to 60 km in width and continues more than 200 km. There are five independent coal bearing parts with 16 coal deposits, which are: Bayantes part, contains Elstei, Khurshuut, Khuvd, Gashuu Tolgoi and Khuren tasv deposits; Ovoot Tolgoi part, contains Sunset and Sunrise deposits; Nariin sukhait part contains West Nariin sukhait, Central Nariin sukhait, East Nariin sukhait and Khuren shand deposits; Sumber part contains Central Sumber, Sumber and Biluut deposits and Jargalant part contains Jargalant and South Biluut deposits.
Result of geochemical study indicates that sediments deposited in the Ovoot khural depression is sourced by the weathering and transporting of intermediate and felsic composition magmatic rocks, mainly from dacite, andesite including minor amount of metamorphic, sedimentary and intrusive rocks.
Spider diagrams of trace element composition of sedimentary rocks of the Orgilokhbulag formation, show Nb-depletion and Pb, Mo enrichment, indicating possible origin of magmatic rocks formed under subduction environment and they are intermediate to felsic in composition. The major trace and rare earth element composition of the Orgilokh bulag formation sedimentary rocks, indicate that the source rocks of sediments might have been formed in the active continental margin tectonic setting.
According to provenance model, coal deposition is undertaking with good tissue preservation, in an alternating environment of oxygenic and deoxygenated swamps.
Based on the metamorphic degree, the temperature of peat compression, the amount of volatile, and the depth gradient of temperature, peat was buried and deposited at a depth of 3500-7000 meters. Low sulfur content, low ash content and low volatile content of coal at the various parts of the depression indicates thet the peat deposition is occurred under two stages.