Yanshiping Gr
Type Locality and Naming
It was named by the Petroleum Reconnaissance Survey Party of Qinghai Province as the Yanshiping Rock Series in 1957-1959. The naming section is located in the Yanshiping area by the Qinghai-Tibet Highway within the territory of Qinghai Province. Schematic strat columns indicate that in the Gaize region (column TJ29), it is an upward succession of an un-named lower unit, then the coeval Bailongbinghe Fm and Danshuihe Fm; and in the Tanggula Mts in the Germu (Golmud) City region (modified column TJ31), it is shown as an upward succession of the Qoimaco Fm (TuotuoheJur Fm, Buqu Fm, Xiali Fm, Suowa Fm, and Zhaworong Fm. It is unclear how to relate these units shown on the schematic strat column to the "members" in the Lithology description that was also provided.
Synonym: （雁石坪群）
Lithology and Thickness
The group comprises the following four members. Lower Sandstone member, which is composed mainly of violet sandstones, occasionally of variegated sandstones, intercalated with a small amount of grey limestones, with a thickness of 1540 m. Lower Limestone member, which is composed of black-grey limestones and marls, intercalated with biotic shelly limestones, occasionally with sandstones, with a thickness of 713 m. Upper Sandstone member, which is composed of an alternating layer of purple and blue-grey sandstones and siltstones, intercalated with black-grey marls, limestones and gypsums, with a thickness of 616 m. Upper Limestone member, which is composed of an alternating layer of purple and blue-grey sandstones, intercalated with marls, with a thickness of over 500 m.
Relationships and Distribution
Lower contact
It is unconformably underlying Cenozoic red beds and volcanic rocks. However, in Tanggula Mts region (column TJ31), it is below the Xueshan Fm of early Cretaceous.
Upper contact
It is unconformably overlying the Triassic Jiezha Gr (column TJ37) or the Permian System.
Regional extent
This group is distributed extensively in the Tanggula Mts region, extending from the Nangqian area on the east to the Zu’erken Mts, Wulanwula Mts, Maduo and Geji areas on the west, its lithology is consistent, and its thickness is smaller on the east and greater on the west, varying in a range from about 5400 m to 6900 m.
GeoJSON
Fossils
All the above-mentioned four members yield abundant faunas. In the Yanshiping area the group yields bivalve fossils such as Eomiodon namynauensis, Protocardia cf. consobrina, P. lamellose, Corbula kidugalloensis, Lopha cf. costata, Tancredia cf. marmoreal, Unio sp., Lamprotula (Eolamprotula) cremeri, Undulatula cf. tanggulaensis, Undulatula, aff. sichuanensis, Cuniopsis johanniboehmi, Cuniopsis sichuanensis, Margaritifera sp., Chlamys (Radulopecten) cf. vagan, Isognomon cf. subplana and Comptonectes sp. In other regions it yields ammonites fossils such as Cyclioceras sp., Reineckia (Kellawaysites) sp., R. (K.) sp. and Dolikephallites sp.; Brachiopod fossils such as Burmirhynchia shanensis, B. namtuensis, B. longa and Holcothyris pinguis; and bivalve fossils such as Astarte nerman, Liostrea tangulaensis, Pseudotrapexium cf. cardiformis, Myopholas acuticostata, Eomiodon namtuensis, E. namynauensis, Camptonectes lens, Opis cf. virdunensis and Inoperna perplicata, and the Lamprotula (Eolamprotula)-Psilunio-Cuniopsis assemblage too.
Age
Depositional setting
This group recorded shallow offshore facies with frequent regress and retreat of the sea.
Additional Information