Jidula Fm
Type Locality and Naming
The naming section is located at Jidula, Zongshan Mountain, west of Gamba County, Tibet. Named by Wen Shixuan in 1974.
Lithology and Thickness
Lithologically represented by a “ferruginous sandstone bed”, consisting predominantly of grayish white quartzose sandstone, marked by yellowish brown, ferruginous, quartzose sandstone at the top and intercalated by light gray, thin-bedded, sandy limestone and calcareous sandstone in the middle and lower parts.
Relationships and Distribution
Lower contact
This formation conformably overlies the Late Cretaceous Zongshan Fm with a clear lower boundary, and is persistent regionally.
Upper contact
This formation has a conformable contact with the overlying Paleocene Zongpu Fm, with clear upper boundary, and is persistent regionally.
Regional extent
It is distributed in Gamba, Dingri and Yadong, and thicker in Tingri, being ~380 m thick, and thins toward the east and west, being generally ~170 m.
GeoJSON
Fossils
It contains foraminifera, ostracods, bivalves, gastropods and algae. The foraminifera are abundant, represented by the Rotalia-Lockhartia assemblage, mainly including Rotalia dukhani, Lockhartia haimei, Smoutina cruysi and Keramosphaera tergestina; there are more than ten genera of ostracods, such as Bairdia, Cytherella and Propontocypris.
Age
Depositional setting
The strata have large-scale cross bedding and are composed of >90% of quartz grains, which are well sorted and rounded. The formation belongs to littoral and neritic deposits.
Additional Information