Also known as Ar Shar Khad
Where: Omnogov, Mongolia (44.1° N, 106.9° E: paleocoordinates 45.5° N, 107.5° E)
• coordinate stated in text
• outcrop-level geographic resolution
When: Mogotuin Formation, Early/Lower Cretaceous (145.0 - 100.5 Ma)
• According to the results of the Russian expedition party (Lopatin, 1980; Sinitsa, 1980), the fossiliferous sites are of the Mogotuin Suite, the lowermost unit of the lower Cretaceous beds distributed in the region. The lower Cretaceous beds were divided into the following suites by Lopatin (1980) in ascending order (from lower to upper): the Mogotuin Suite, the Manlai Suite, the Shinkhuduk Suite, the Khukhutek Suite, and the Sainshand Suite.
• group of beds-level stratigraphic resolution
Environment/lithology: lacustrine - large; mudstone
•We opened 11 quarries for detailed searching for fossils in mudstone (shale). The horizon of the excavated quarry in shale is variable.
•There are lenticular intercalating beds of conglomerate and sandstone in the shale. The thickness of the coarse-grained beds is between lcm and 2m. The lateral extension of the coarse-grained beds is limited up to 100m. On the upper surface of the coarse-grained rock layers, especially sandstone layers, ripple marks were preserved. The coarse-grained sediments are interpreted as the feeder channel deposits from the coastal region of the early Cretaceous lake in Manlai to a remote area of the lake where the mud (shale and paper shale at present) was accumulated. In the shale and paper shale, isolated well-rounded conglomerate (diameter: 0.5-5cm) are visible. The thickness of the visible section of the Mogotuin Suite was measured to be 163m (Plate 1).
•The thickness of the Mogotuin Suite between the upper limit of the visible section and the boundary between the Mogotuin and the overlying Manlai Suites is cartographically calculated as about 110m. Therefore, the total thickness of the Mogotuin Suite (from the basal conglomerate to the upper boundary) is about 273m.
•The dipping direction and dipping angle of the shale and sandstone layers of the Mogotuin Suite is: 15/23.5; 15/20.5; 30/23; 12/24; 44/24; 23/27; 45/32; 34/30; 50/29; 35/24; 36/30; 21/35; 31/50; 36/22.5; 38/22.5; 30/29; 34/39; 18/30; 32/35. The beds of the Mogotuin Suite dip to NE (30.5 degree in average) with angle of 28.9 degree on average
Size class: macrofossils
Preservation: adpression, soft parts
Collected by HMNS-GIN in 2001
Collection methods: quarrying, mechanical,
Primary reference: M. Watabe, K. Tsogtbaatar, N. Ichinnorov and R. Barsbold. 2004. Report on the Japan-Mongolia Joint Paleontological Expedition to the Gobi desert, 2001. Hayashibara Museum of Natural Sciences Research Bulletin 2:69-96 [R. Benson/R. Benson]more details
Purpose of describing collection: general faunal/floral analysis
PaleoDB collection 137860: authorized by Roger Benson, entered by Roger Benson on 28.12.2012
Creative Commons license: CC BY (attribution)