Tarap Fm
Type Locality and Naming
Upper-middle formation in Thinigaon Gr. "The unit, largely consisting of siltstones to ®ne-grained
sandstones (Tarap Shales of Fuchs, 1977), was very rapidly and monotonously deposited at early Norian times from Nepal to S. Tibet (Krystyn, 1982; Jadoul et al., 1998)."
Lithology and Thickness
Siltstone to fine-grained sandstones. 400 to 500 m.
Relationships and Distribution
Lower contact
Overlies the Mukut Fm
Upper contact
Overlain by the Yak Kharka Fm
Regional extent
"It displays only broad similarities with the lower Norian terrigenous units of the Spiti±Zanskar
Synclinorium (middle member of the Nimaloksa Fm. to "Juvavites beds''; Garzanti et al., 1995). Major ironstones such as those occurring in the lower part of the Alaror Group both in Zanskar (Garzanti et al., 1989; Jadoul et al., 1990) and Spiti (I1 and I2 intervals of Garzanti et al., 1995, Figs. 7, 8, 12, 13) have never been reported from Nepal or S. Tibet so far." Thickness varies from "about 500 m in the central Dolpo type area and over 330 m in the Manang to the Burhi Gandaki/Shiar area."
GeoJSON
Fossils
Age
Depositional setting
" Very-fine-grained terrigenous detritus, which began at different times along the Tethys Himalaya during the Middle Triassic and increased upward in abundance in the Carnian, became dominant after the mid-early Norian, when the phosphatic mudrocks to fine-grained sandstones of the Tarap Fm suddenly began to be deposited in shelf settings, reaching 500 m in thickness in Nepal and approaching even 1000 m in S. Tibet (Jadoul et al., 1998)."
Additional Information