Manlai, paper shales [HMNS-GIN] (Cretaceous of Mongolia)

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

• The Mogotuin Suite consists mainly of shale and paper shale.

•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)

Taxonomic list

 Pancrustacea -
Hexapoda indet. Latreille 1825
There are several insect species that are common to those found from the lower Cretaceous shale (paper shale) of Abdrant Nuru (cen tral Gobi region, east of the Arts Bogd Mountain) in 2000
Branchiopoda
 Phyllopoda -
Phyllopoda indet. Preuss 1951 branchiopod
phyllopods
Osteichthyes
 Osteichthyes -
Osteichthyes "indet. 1" Huxley 1880 bony fish
Fish fossils were well preserved, and the outline of the soft-part of their bodies is also well represented on the shale bedding plane. There are more than 2 different species of fish distinguished by body proportion
Osteichthyes "indet. 2" Huxley 1880 bony fish
Fish fossils were well preserved, and the outline of the soft-part of their bodies is also well represented on the shale bedding plane. There are more than 2 different species of fish distinguished by body proportion
Aves
 Aves -
Aves indet. bird
bird feathers
 Tracheophyta -
unclassified
  -
Angiospermae indet. Mabberley 2000
Several leaves of possibly angiosperm plant were also found