Shuangputang Fm
Type Locality and Naming
The type section is located at Shuangputang about 70 km to the north of the Jinta County Town, Gansu Province. It was named by Xiu Zelei and Zhao Xiangsheng in 1964 (the Institute of Geology under the former Ministry of Geology, 1964).
Lithology and Thickness
Sandstone. Composed of grey-green, grey and yellow-green sandstones, intercalated with black sandy shale and sandy limestone lenses, with a thickness of 1005 m. Its basal part is composed of yellow-green fine-grained sandstone, intercalated with sandy limestone and limestone lenses, with a thickness of 60 m.
Relationships and Distribution
Lower contact
Unconformable contact with the underlying Ganquan Fm
Upper contact
Conformable contact with the overlying Jushitan Fm
Regional extent
Distributed in an EW-trend in the Beishan Mt. area, and is divisible into 3 facies belts. The southern facies belt in the Hongliuyuan area and the northern facies belt in the Heiying Mt. area represent intertidal-zone clastic-rock deposits, and are composed mainly of conglomerate, sandstone, siltstone and a small amount of sandy limestone, and it is associated with basic volcanic effusion in the early stage of its formation, with a thickness of 1500 m. The central facies belt in the Mazhong Mt. area represents subtidal clastic-rock and carbonate deposits, with a thickness of 500-800 m.
GeoJSON
Fossils
Yields Ammonoids such as Uraloceras, Demarezites, Medlicottia, Neocrimites, Artinskia and Propinacoceras; and Brachiopods represented by Waagenoconcha cf. abichi, Aulosteges gigantiformis, Spiriferella salteri, Liosotella spitzbergiana, Licharewia grewingki, Leptodus nobilis, Yakovlevia mammatiformis, etc.
Age
Depositional setting
It is interpreted intertidal-zone clastics adjacent to a central belt of subtidal clastic-rock and carbonate deposits.
Additional Information