Shaqiaomu Fm
Type Locality and Naming
It was named by Wu Ruizhong in 1986. The naming section is located at the Shaqiaomu Mts, Shaiwa region of Shuanghu Agency of Tibet (E 89°30′, N 32°30′).
Synonym: （莎巧木组）
Lithology and Thickness
The formation is composed of alternating layers of black quartz-sandstones and grey-black and black mudstones, intercalated with siltstone. Lower part consisting of alternating layers of light-grey lithic quartz-sandstone in association with black mudstone. Middle part consisting of alternating layers of grey lithic quartz-sandstone, black siltstone in association with mudstone. Upper part consisting of alternating layers of grey-green and grey-black lithic quartz-sandstones in association with mudstone, intercalated with shelly limestone. Its thickness is of over 1015 m.
Relationships and Distribution
Lower contact
Its basal part consisting of an alternating layer of grey quartz-sandstone in association with black-mudstone is in a conformable contact with the grey-black mudstone and limestone from the underlying Shaiwa Fm (J2) (= Sewa Fm).
Upper contact
No top part of it has been found. Regionally (column TJ30a), the next younger unit is the Bailongbinghe Fm of late Jurassic through basal Cretaceous.
Regional extent
The formation is distributed only in the area of the Shaqiaomu Mts of the Shuanghu region with a consistent lithology.
GeoJSON
Fossils
In the Jienu area it yields the middle Jurassic bivalve fossils as represented by Modiolus sp., Mytilus sp., Liostrea cf. dubiensis, L. birmanica, Chlamys grisbashi, C. laevis, Lopha asella namtuensis and Protocardia stricklandi, as well as coral and Brachiopod fossils.
Age
Depositional setting
It belongs to shallow-sea-bathymetric mudstone-facies and quartz-sandstone-facies deposits.
Additional Information