Zhaworong Fm
Type Locality and Naming
It was named by Bai Shenghai in 1989. The naming section is located at 7 km southeast of Qoimaco, Tanggula Township, Germu (Golmud) City, Qinghai Province, with its reference section being situated at the Wenquan Army Service Station by the Qinghai-Tibet Highway within the territory of Qinghai Province (Regional Survey Party of Qinghai Province, 1987). Schematic strat column in previous "red Chinese Lexicon" suggests it is the uppermost formation in the Yanshiping Gr.
Lithology and Thickness
Composed of grey-white and grey-green medium-, and fine-grained lithic quartz-sandstones, sandstones, pebble-bearing sandstones, limestones, conglomerates and argillaceous siltstones, with its basal part consisting of predominant violet alternating with grey and variegated sandstones, intercalated with siltstones and a small amount of limestones and sandy conglomerates. It is 659.4-941.6 m in thickness.
Relationships and Distribution
Lower contact
Its basal part being in a conformable contact with the underlying Wasuo Fm (? not in Lexicon or in China strat names). Entry for Suowa Fm says it is in a conformable contact with the overlying Zhawuorong Fm; therefore this relationship is used in the graphics pending clarification.
Upper contact
No top part of the formation has been found. Regionally, the next younger unit seems to be the mid-Cretaceous Xueshan Fm (needs clarification).
Regional extent
The formation is distributed essentially in the area extending from the Qoimaco region to the Wenquan Army Service Station, with a remarkable variation in its lithology as proved by its clastics grains getting coarser in ascending order and in a direction from southwest to northeast, with a thickness varying from 659 m to 1318 m.
GeoJSON
Fossils
In the area of the Wenquan Army Service Station it yields bivalves as represented by Laevitrigonia gibbosa, Cypricardia cf. loweana and Myopholas multicostata. And in the Qoimaco region it yields such bivalves as Questedra sp., Peregrinoconcha yunnanensis and P. perlenga, as well as spore-pollen fossils as represented by Deltoidospora, Concavisporites, Duplexisporites, Classopollis, Cycadopites, Perinopollenites, Psophosphaera and Convolutisporis.
Age
Depositional setting
The lower part of this formation represents marine deposits, while its upper part represents remnant-sea lagoon-facies deposits.
Additional Information