Qugasi Fm
Type Locality and Naming
The original Qugasi Formation represents a set of strata dominated by carbonate rocks in the Late Triassic Carney in Yidun area, Sichuan. According to the mixtures of Carney and Nori organisms in the group, the age of the group was defined as Carney to early Nori by the Sichuan Diaoduan and Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (1982). This book maintains the original meaning of Qugasi Formation. The named section is located in Quga Temple, about 1 km east of Yidun, Batang County, Sichuan Province.
Synonym: Gasi Fm
Lithology and Thickness
Lower part is thick gray limestone, containing flint bands and bioclasts, interbedded with unstable dark green almond-shaped basalt, with a thickness of 684.7 m. Middle part is grey medium thick feldspar quartz sandstone plywood with a thickness of 450 m. Upper part is thick gray dense limestone interbedded with phyllite, 216 m thick. The top is gray phyllite intercalated with lithic sandstone, 91 m thick.
Relationships and Distribution
Lower contact
The bottom boundary in the Muli part of Yidun region is delimited from the underlying Masuoshan Fm by the chert stripe limestone, which is in false conformational contact with the underlying strata. In Batang-Baiyu part, the underlying unit is the Lieyi Fm.
Upper contact
The top is in a false conformational contact with the bottom conglomerate of the overlying Tumugou Fm.
Regional extent
Yidun region; Batang County, Sichuan.
GeoJSON
Fossils
Fossils such as ammonoids, bivalves, brachiopods, gastropods, corals, hydrops, sponges, algae, conodonts and so on are produced in the upper strata, and the petrel clam is the main one. Tropites-Halobia superba can be found, and the important conodont is Eigondolella diebeli.
Age
Depositional setting
It is interpreted as littoral and shallow sea deposits.
Additional Information
[This was in the original Lexicon entry from the compilers; but unsure why:] The Baiyugunna Formation is dominated by clastic rocks with a thickness of more than 1000 meters. In the west of Baiyu Ase, the lower part of the formation is dominated by clastic rocks, mixed with metamorphic basic volcanic rocks and manganese siliceous rocks, and the upper part is crystalline limestone with a thickness of 940 m. In Zhengdou, Derongriyu and Baisong of Xiangcheng, the formation is sand-slate and contains right collapsing limestone blocks of Devonian, Carboniferous and Permian.