Xiangtang Fm
Type Locality and Naming
It was named by Miao Qingxiang as the Xiangtang System in 1954, and was first cited publicly in the 《Regional Stratigraphic Charts of China (draft)》in 1956. The naming section is located in the vicinity of the Xiangtang Village, Minhe County, Qinghai Province, with the profile extending from the Zhu’erzhuang Village to the Mazhuang Village, Yaojie Street of Lanzhou City, Gansu Province serving as its reference section.
Synonym: （享堂组）
Lithology and Thickness
It is composed largely of purple sandstone, gritstone and conglomerate, with a thickness of less than 100 m.
Relationships and Distribution
Lower contact
Its lower part was cut by fault, and for this reason no base of the formation has been found. Regionally, the next older unit is the Tieyegou Fm or the Muri Fm.
Upper contact
No top found. Regionally, it can be overlain unconformably by the Hekou Gr
Regional extent
The formation is distributed in Minhe and Ledu Counties of Qinghai Province and Lanzhou City and Yongdeng County of Gansu Province. In the Yaojie area of Lanzhou City the formation is composed of grey-green clay, yellow-green sandstone and purple clay, with its basal part consisting of a 7.6m-thick layer of grey-white pebble-bearing sandstone being in a disconformable contact with the grey-green clay from the top part of the underlying Yaojie Fm, with a thickness of 660.7 m. In the area of the Lama Gully, Yongdeng County and the Huishan Mts of Tianzhu County, the lithology of the formation is similar to that found in the Yaojie area, but with a thickness of 252 m in the former area, and with a thickness of only 67.2 m in the latter area. In the Jishiguan area of Minhe County, the rocks of the formation are getting coarser, containing more conglomerates, with a thickness increasing up to 896.8 m.
GeoJSON
Fossils
In the Xiangtang Gorge the formation is found to yield Chareae fossils such as Euaclistochara yunnanensis, E. nuguishanensis and E. lufengensis var. minor, and yielding also Dinosaur fossils in the Hanjiahu area to the north of Xiangtang as represented by Mamenchisaurus hochuanensis, as well as Crocodilia fossils as represented by Sunosuchus miaoi.
Age
Depositional setting
Additional Information