Wulgai Formation
Triassic
Kirthar Basin · Western Kirthar (Balochistan)
Part of Khanozai Group
Triassic in the time scale →Cited in 6 sources Last reviewed Aug 2, 2026
- Rank
- formation
- Status
- Published
- Age
- Mesozoic · Triassic · TriassicTriassic
- Named by
- Williams (1959)
- Type locality
- Tarkai-Gwal section, Axial Belt
- Thickness
- 180 m
- Lithology
- Indurated dark-grey mudstone and shale with intercalations of thin limestone, calcareous mudstone and sandstone.
- Synonyms
- Alozai Group / Shirinab Formation / Winder Group (earlier mappings, HSC 1960); Wulagai
A Triassic dark mudstone-and-shale, the base of the Mesozoic sequence in western Balochistan.
Wulgai Formation Wulgai is named by Williams 1959 after Wulgai village for variegated shale with medium bedded limestone of Middle to Late Triassic age exposed in the Western Indus Suture regions like Shirinab area of Mastung and Kalat, Khanozai, Zhob, etc. It is 180 m thick in the Trakai-Gwal section. Its lower contact with Gwal is sharp with fossiliferous conglomeratic and dense limestone and upper contact with Spingwar formation seems to be conformable. The fossils like radiolarian, conodonts and some Spiriferinid brachiopods in basal limestone indicates Middle Triassic age and Holobia, 70 Daonella (Bivalves) and ammonites like Cladescites, Jovites, Arietoceltites, Anatomites, Juvavites, Arcetes indicating Late Triassic.
Fossils
Contacts
Band colour = period; texture = dominant rock type. Lines between bands mark the contact type. True scale makes height ∝ recorded thickness; hatched = thickness not recorded. Ages approximate, for ordering.
This unit (highlighted) within its province column; faded ends continue above and below. Line style marks the contact type.
Distribution & setting
- Basin
- Kirthar Basin
- Region
- Western Kirthar (Balochistan)
- Depositional environment
- marine
- Coordinates
- Not recorded
Correlation
Not recorded. Compare this unit against other basins on the correlation panel →
Economic significance
Part of the frontier Triassic–Jurassic carbonate petroleum play of the Sulaiman Fold-Thrust Belt; dolomitization of the Wulgai Formation carbonates has locally produced secondary porosity.
Remarks
A Triassic mudstone-shale unit of the Balochistan ophiolite-and-thrust belt (Zhob, Kalat, Khuzdar), also encountered in Lower Indus wells; the base of the Mesozoic succession there.
Sources (6)
- Malkani, M.S. & Mahmood, Z. (2017). Stratigraphy of Pakistan. Geological Survey of Pakistan, Memoir Vol. 24.
- Kazmi, A.H. & Jan, M.Q. (1997). Geology and Tectonics of Pakistan. Graphic Publishers, Karachi.
- Indian Plate Lexicon (indplex.geolex.org), Geological Society of India and international compilation.
- Shah, S.M.I. (2009). Stratigraphy of Pakistan. Geological Survey of Pakistan, Memoir Vol. 22.
- Kazmi, A.H. & Abbasi, I.A. (2008). Stratigraphy and Historical Geology of Pakistan. Department & National Centre of Excellence in Geology, University of Peshawar, Peshawar. 524 pp. ISBN 978-969-9119.
- Razzaq Abdul Manan, Kassi, A.M., Friis, H., Kasi, A.K., Ali, S.H., Farooqui, M.A. & Kakar, M.I. (2024). Deposition and diagenesis of the Triassic-Jurassic limestone successions of the northwestern passive margin of the Indian plate, Sulaiman Fold-Thrust Belt, Pakistan. Carbonates and Evaporites, 39, 104.
Reviewer confidence: high
Every fact on this page is source-cited. This entry is part of the peer-archived Pakistan Stratigraphy Dataset (doi.org/10.5281/zenodo.21363991, CC‑BY‑4.0).
Lexicon status: Name attested in the Shah (1977/2009) Geological Survey of Pakistan compilation — the national stratigraphic lexicon. This records where the name is documented; it is not an endorsement of the unit’s definition, age or figures.
Cite this unit
Qudsi, L. (2026). Wulgai Formation. In Pakistan Stratigraphy Dataset [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21363991
@misc{stratigraphypk_wulgaiformation,
author = {Qudsi, Lareb},
title = {{Wulgai Formation} --- Pakistan Stratigraphy Dataset},
year = {2026},
publisher = {Zenodo},
doi = {10.5281/zenodo.21363991},
url = {https://doi.org/10.5281/zenodo.21363991}
} Archived dataset: doi.org/10.5281/zenodo.21363991 (CC‑BY‑4.0) · Direct link to this entry: https://stratigraphy.pk/formation/wulgai-formation (accessed August 30, 2026).
To cite the unit's original definition instead, see: Williams (1959).
Related units
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