Suowa Fm
Type Locality and Naming
Qiangtang Basin. Suowa is close to Tanggula Mountain (Tanggulashan; ca. 33.5N, 91.1E), SW Qinghai Province. It was named by Bai Haisheng in 1989. The naming section is located at 7 km southeast of Quemuoco, Tanggula Township, Germu City, Qinghai Province, with its reference section being situated at Yenshiping by the Qinghai-Tibet Highway, Qinghai Province (Regional Survey Party under the Geological Bureau of Qinghai Province, 1972). Second-highest formation within the Yanshiping Gr.
Synonym: （索瓦组）
Lithology and Thickness
The formation is composed of an alternating layer of dark-grey and grey-green argillaceous and calcareous siltstones in association with grey-white cryptocrystalline and microcrystalline limestones and bioclastic limestone. Upper member (which might now be named the Zhawuorong Fm?) is variegated sandstone and siltstone. Total thickness of 940.5 m.
Relationships and Distribution
Lower contact
Its basal part is in a conformable contact with the underlying Xiali Fm.
Upper contact
In the Quemuo Co and Hot Spring regions the particular formation is in a conformable contact with the overlying Zhawuorong Fm, while in other regions it is overlain unconformably by the lower Cretaceous conglomerate and/or by the Tertiary volcanic rock formation.
Regional extent
The formation is distributed in the form of a belt extending from Chibuzhang Co through Jiamucheng Co and Maiqu of Suowa to Longba of Bangga, with greater variations both in its lithology and thickness. In the Yenshiping region its visible thickess is of over 389 m; and is of 601 m at the Hot Spring Army Servic Station.
GeoJSON
Fossils
It yields bivalve fossils as represented by the Gervillia aviculoides-Radulopecten fibrosus assemblage whose key members comprise Radulopecten fibrosus, Gervillia aviculoides, Plagiostoma cf. escheri, Pteroperna polydom, Avicula burensis, Astarte cf. numus, Entolium coreneolum, Myopholas cf. manderaensis, Protocardia cf. purbeckensis and Modiolus holesa; as well as Brachiopoda fossils occurring at the horizon corresponding to the basal part of the section in the Gladandong region such as Septaliphoria septentrionalis, Pentithyris cf. pllagica and Thurmanella acuticosta.
Age
Depositional setting
Additional Information
Wan Xiaoqiao (partial – was also a Cret Lex entry)