Paleozoic • Permian In GSP lexicon

Tobra Formation

Early Permian (Asselian-Sakmarian)

Cited in 12 sources Last reviewed Aug 20, 2026

Unit summary

Rank: Not recorded
Status: Published
Age: Paleozoic · Permian · CisuralianEarly Permian (Asselian-Sakmarian)
Named by: Hussain (1967)
Type locality: Tobra Nala, Salt Range
Thickness: 30-150 m
Lithology: Tillite, diamictite, boulder beds with striated clasts
Synonyms: Talchir Boulder Bed

The lowest unit of the Permian Nilawahan Group: a glacial tillite and diamictite with striated boulders and dropstones left by the great late-Paleozoic (Gondwanan) ice age.

Named after Tobra Nala in Salt Range. Glaciogenic deposits from the Late Paleozoic (Gondwanan) glaciation. Contains striated boulders and dropstones. Part of the Nilawahan Group.

Fossils

Glossopteris Gangamopteris Rare marine fauna in interbeds

Contacts

In the Salt Range column

SandstoneMixedFossils recordedConformable

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

Salt Range Kohat Basin Potwar Basin

Basin: Not recorded
Region: Not recorded
Depositional environment: glacial, glaciofluvial
Coordinates: Not recorded

See it in the field

Geoheritage sites where this unit is exposed at outcrop.

Salt Range Escarpment (Khewra–Choa Saidan Shah)

Salt Range

Nilawahan Gorge — Tobra Formation glacial tillite

Salt Range

Correlation

Not recorded. Compare this unit against other basins on the correlation panel →

Economic significance

Reservoir

Local reservoir (primary + dissolution porosity; fractured sandstones); flowed oil in the Adhi field. Typical Rw ~0.04 ohm-m, salinity ~85,000 ppm NaCl. Top Tobra is a strong, laterally continuous seismic reflector in East Potwar.

Remarks

A glaciogenic diamictite recording the late Paleozoic Gondwanan glaciation on the northern margin of Gondwana; it rests with marked unconformity on the Cambrian and yields a Gangamopteris-Glossopteris flora consistent with an Asselian age.

Sources (12)

Malkani, M.S. & Mahmood, Z. (2017). Stratigraphy of Pakistan. Geological Survey of Pakistan, Memoir Vol. 24.
Shah, S.M.I. (1977). Stratigraphy of Pakistan. Geological Survey of Pakistan, Memoir Vol. 12.
Ghazi, S., Mountney, N.P., Butt, A.A. & Sharif, S. (2012). Stratigraphic and palaeoenvironmental framework of the Early Permian sequence in the Salt Range, Pakistan. Journal of Earth System Science, 121(5), 1239-1255.
Indian Plate Lexicon (indplex.geolex.org), Geological Society of India and international compilation.
Kadri, I.B. (1995). Petroleum Geology of Pakistan. Pakistan Petroleum Limited, Karachi.
Shah, S.M.I. (2009). Stratigraphy of Pakistan. Geological Survey of Pakistan, Memoir Vol. 22.
Kazmi, A.H. & Jan, M.Q. (1997). Geology and Tectonics of Pakistan. Graphic Publishers, Karachi.
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.
Gee, E.R. (edited by Gee, D.G.) (1989). Overview of the geology and structure of the Salt Range, with observations on related areas of northern Pakistan. In: Malinconico, L.L. & Lillie, R.J. (eds) Tectonics of the Western Himalayas. Geological Society of America Special Paper 232, 95-112.
Malik, I.A. (1989). Geodynamics and Coal Deposits of Pakistan. Geological Bulletin of the Punjab University, 24, 12-43.
Hemphill, W.R. & Kidwai, A.H. (1973). Stratigraphy of the Bannu and Dera Ismail Khan Areas, Pakistan. U.S. Geological Survey Professional Paper 716-B (Geological Investigations in Pakistan), 36 p.
Craig, J., Hakhoo, N., Bhat, G.M., Hafiz, M., Khan, M.R., Misra, R., Pandita, S.K., Raina, B.K., Thurow, J., Thusu, B., Ahmed, W. & Khullar, S. (2018). Petroleum systems and hydrocarbon potential of the North-West Himalaya of India and Pakistan. Earth-Science Reviews, 187, 109-185.

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

APA

Qudsi, L. (2026). Tobra Formation. In Pakistan Stratigraphy Dataset [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21363991

BibTeX

@misc{stratigraphypk_tobraformation,
  author    = {Qudsi, Lareb},
  title     = {{Tobra 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/tobra-formation (accessed August 30, 2026).

To cite the unit's original definition instead, see: Hussain (1967).

Below · older

Baghanwala Formation

Cambrian

Above · younger

Dandot Formation

Permian

Referenced in other successions

Underlain by Khisor Formation