Spiti Fm
Type Locality and Naming
Left bank of Spiti River in Spiti. [Original Publication: Stoliczka, F. 1865. Geological section across the Himalayan mountain range from Wangtu Bridge on the river Sutlej to Sungdeo with an account of formations in Spiti accompanied by a revision of all known fossils from that district. Memoirs of Geological Survey of India, 5: 153p]
Synonyms: Spiti Shale.
[Figure: Zanskar-Spiti-Kumaun region location (provided by Om Bhargava)]
Lithology and Thickness
Claystone. Comprised of pyritiferous and splintery black shales with locally, intercalated marls and calcareous quartzite, siltstone. Rare very fine-grained sandstones and thick beds of graded bio-calcirudite or lags. 90-250 m thick, thickness increases eastward. In Zanskar it is about 20-62m (in Spiti >900m).
Relationships and Distribution
Lower contact
It has a conformable contact with the underlying Tagling Fm (Ferruginous Oolite Fm)
Upper contact
Gradational contact with the overlying Giumal Fm.
Regional extent
Zanskar-Spiti and Himachal Pradesh to Kumaun-Garhwal region of Northwest Tethyan Himalaya
GeoJSON
Fossils
Renown for its Belemnites and ammonites. Epimayaites lemoini, Prograyiceras sp., Grayiceras koeneni, Belemnopsis sp., Hildoglochiceras latistrigatum. Ammonoid assemblage zone: Himalayites Zone; Virgalosphinctes Zone; Spiticeras Zone; Patchysphinctes Zone; Torquatisphinctes Zone and Mayaites Zone.
Age
Depositional setting
The unit was deposited on mid-shelf with low rate of sedimentation and poor circulation with occasional hurricane and local turbidity currents/mudflows (Bhargava, 2008).
Additional Information
Not available.