Guchang Gr
Type Locality and Naming
The type section is located at the western slope of Guchang Village, Marmê (Mami) District, Gêrzê County, Tibet. It was named by the Regional Geological Survey Party of Tibetan Bureau of Geology and Mineral Resources in 1987.
Lithology and Thickness
Sandstone, Glacial pebbled-claystone, and Limestone. Gray fine-grained sandstone interbedded with gray-green and black-gray shale, siltstone and bioclastic rock in unequal thickness, in which the quartzose sandstone is of higher content than the other rocks, and tends to increase upward. Ripple marks, oblique beddings and worm trails are also seen in the sandstone and mudstone, and the rocks are mainly thin bedded. In the pebbled slate and pebbled siltstone, the pebbles are granite and limestone related to glaciation, which have varied sizes and shapes, mostly of good roundness, and penetration of bedding is occasionally seen. The limestone is brachiopod-dominant organic limestone or bioclastic limestone. The total thickness exceeds 2283 m.
Relationships and Distribution
Lower contact
Conformable contact with the underlying Lower Carboniferous Qusuma Fm
Upper contact
Uncertain: Top is not exposed
Regional extent
It outcrops around Guchang of Mami District, southwest Gêrzê County, and the corresponding strata are also distributed in Yunzhug Township, Xianza County, generally trending near E-W
GeoJSON
Fossils
Lower part yields Brachiopods Choristites sp., Phricodothyris sp. and Linoproductus sp.; Corals Amplexus sp. and Plerophyllum sp. Upper part contains Brachiopods ?Stenoscisma sp., Neospirifer sp., Alispirifer ? sp., Globiella sp., etc.
Age
Depositional setting
It is interpreted as a possibly littoral facies and estuarine deltaic facies
Additional Information