Paleozoic • Permian In GSP lexicon

Tobra Formation

Early Permian (Asselian-Sakmarian)

Cited in 13 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 Range32.6300°N, 72.3500°E
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 recordedContact not recorded

Band colour = period; texture = dominant rock type. Lines between bands mark the contact type; dotted = no contact recorded in the sources (not a claim of conformity). 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: 32.6300°N, 72.3500°E

Google Maps ↗ OpenStreetMap ↗

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.

Research notes (9)

Field-by-field findings drawn from the cited literature. Every statement is traced to a registered source — follow a citation for the full reference.

Name & nomenclature (1)

Ghazi et al. (2012): the Tobra Formation was previously known as the Talchir Boulder Bed (Noetling 1901) in Pakistan.

Ghazi, S., Mountney, N.P., Butt, A.A. & Sharif, S. (2012)

Age & correlation (2)

Ghazi et al. (2012), full text: the Tobra Formation is largely Asselian, fixed by the Glossopteris-Gangamopteris floral assemblage (Balme in Teichert 1967; Gee 1989). Tillite, diamictite and freshwater facies recording late-glacial to post-glacial Gondwana deposition; correlates with the Dwyka Group (Karoo, S Africa) and the Talchir Formation (India). Type locality: Tobra village, eastern Salt Range (formalized by the SCP, Fatmi 1973).

Ghazi, S., Mountney, N.P., Butt, A.A. & Sharif, S. (2012)
Kazmi & Jan (1997): the Tobra Formation (Early Permian, on Striatopodocarpites/Protohaploxypinus palynology; type Tobra village) is 20 m (to 120–130 m in Zaluch Nala) of polymict conglomerate/tillite in the east and diamictic fluvioglacial mudstone in the west, resting unconformably on Cambrian units or the Salt Range Formation and conformably overlain by the Dandot Formation; glacial to fluvioglacial, with Glossopteris/Gangamopteris flora.

Kazmi, A.H. & Jan, M.Q. (1997)

Thickness (1)

Type-section thickness (Shah, 2009): >133 m at Zaluch Nala (western Salt Range, max); ~33 m eastern Salt Range; 0–25 m central Salt Range. Recorded from the GSP lexicon (Memoir 22); the existing thickness field is retained.

Shah, S.M.I. (2009)

Type locality & location (1)

Geocoded (low confidence) from the published type locality "Tobra Nala, Salt Range" via public gazetteer (OpenStreetMap / GEOnet Names Server). Named-place point of ~km accuracy for regional screening, not a surveyed section; author-reviewed in the coordinate-verification pass. Basis: Tobra Nala, central Salt Range.

OpenStreetMap contributors and GEOnet Names Server (public geographic gazetteers), used to geolocate named GSP type localities to approximate decimal coordinates.

Economic significance (2)

Malik (1989): the Permian Tobra Formation hosts the earliest coal in Pakistan, at Buri Khel at the top of the formation (Asselian) - a detrital, sub-vitreous coal with a maximum seam ~162 cm (and ~3 m at Sarai Sindhu near Multan, in the subsurface). Permian coal is regarded as of theoretical interest only, essentially sub-economic (an alternative placement by Raza et al. 1977 put this coal in the Warcha Sandstone).

Malik, I.A. (1989)
Craig et al. (2018): the Lower Permian Tobra Formation is a producing reservoir with fair-good properties in the Kal, Rajian and Dhurnal fields (SE Potwar Plateau); its oil is generally attributed to Infra-Cambrian source rocks.

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)

Geological significance (2)

Gee (1989): the Early Permian Tobra Formation (former 'Talchir Conglomerates') is a fluvio-glacial conglomerate marking the base-of-Permian major unconformity — it oversteps the Cambrian westward and northward to rest directly on the Salt Range Formation in the western range. Overlying clastics carry a Gangamopteris–Glossopteris (Gondwana) flora, recording the range's connection with the Gondwana continent; boulders are mainly igneous or metamorphic.

Gee, E.R. (edited by Gee, D.G.) (1989)
Hemphill & Kidwai (1973, USGS PP 716-B): in the Khisor Range the Tobra Formation is the basal unit of the Early Permian Nilawahan Group (~822 ft SE of Paniala) - a lower conglomerate of striated ellipsoidal boulders (quartzite, granite, gneiss, mafics) grading up into siltstone and sandstone; its basal 'Talchir boulder bed' was argued to be of glacial origin (Gee 1945; B. Sahni 1939).

Hemphill, W.R. & Kidwai, A.H. (1973)

Sources (13)

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.
OpenStreetMap contributors and GEOnet Names Server (public geographic gazetteers), used to geolocate named GSP type localities to approximate decimal coordinates.

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.

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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 October 29, 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