Xiangadong Fm
Type Locality and Naming
The named section is located in Xiangadong, Jianzha County, Qinghai Province. Qinghai Bureau of Geology named this formation in 1960, Qinghai Bureau of Geology Area Survey team first public citation in 1966. The named section is located in Xiangadong, Jianzha County, Qinghai Province. The original Xiangadong Fm represents the platform type deposits of the early-Middle Triassic Anisian in eastern Qinghai. Rao Rongbiao et al (1987) argued that the Xiangadong Fm should be distinguished from the Gulangdi Fm, which represents the contemporaneously geosyncline type deposits. Qinghai Bureau of Geology and Mineral Resources (1991) referred them as Gulangdi Fm. Yang Zunyi et al. (2000) followed Rao Rongbiao et al (1987), which is used in this Lexicon.
Synonym: Xiang’adong Fm, because the town is also called Xiang’adong.
Lithology and Thickness
It is mainly composed of light gray sandstone, gravel sandstone, limestone, claystone and coarse sandstone. Thickness is 243 m.
Relationships and Distribution
Lower contact
It is unconformity contact with the underlying pre-Sinian. Regionally, the next older unit is the Longyangxia Gr of early Triassic.
Upper contact
Regional extent
Distribution is limited, only found in Xiang‘adong and Bali temple of Jianzha County, Moxiatan of Weiyuan, Pangjiashigou Qin’an, Tarigate Wulan and other places.
GeoJSON
Fossils
Ammonoids: Sturia cf. semiarata, Leiophyllites cf. indoaustralica, Gymnites humboldti, Semiornites marmarensis, Trachyornites qinghaiensis; Brachiopods: Mentzelia sp., Cotispiriferina tsinghaiensis, etc.
Age
Depositional setting
The formation is a stable littoral to foreshore shallow-marine deposit.
Additional Information