Huashugou Fm
Type Locality and Naming
NW Gansu-south Qinghai border region (middle Qilian). The Huashugou Fm was named by the No.6 Team, Qilianshan Party of Geology, Ministry of Geology in 1956. The type section is in the Jingtieshan ore District, west of Beida River in Qiqing Township, Sunan Yugu Autonomous County, Gansu Province. The formation is attributed to the upper part of the Zhulongguan Gr.
Synonym: （桦树沟组）
Lithology and Thickness
In the type section, the formation is composed of flysch-type interbedding of grey to grey-green phyllite with grey yellow meta-siltstone and fine sandstone, its upper part is intercalated with carbonate rock, metamorphosed quartz sandstone, volcaniclastic rock and iron ore, with the latter being the characteristic indicator. The Huashugou Fm is about 2400 m thick.
Relationships and Distribution
Lower contact
The basal conformable contact onto the underlying volcanics of the Aoyougou Fm is seen in the Aoyougou section, Qiqing Town, Sunan County.
Upper contact
Unconformably overlapped by the Nanbaishuihe Fm (lower formation of the Tuolainanshan Gr)
Regional extent
NW Gansu-south Qinghai border region (middle Qilian). It extends from upstream of Heihe River in the east to Shibandun-Yingzui Mountain in the west. It has considerable lateral variability both in lithological character and thickness. For example, it is up to 3515 m thick around Jingtie Mountain, but it is only 959 m thick on south side of Zhulongguan River. The volcaniclastic rock increases gradually from east to west, and the siliceous, argillaceous and carbonate contents increase in the same direction.
GeoJSON
Fossils
The carbonate in the upper part has stromatolites: Kussiella f., Colonnella f., Baicalia cf. rara.
Age
Depositional setting
Additional Information