Cenozoic • Paleogene formation In GSP lexicon

Sohnari Formation

Late Paleocene (to earliest Eocene)

Kirthar Basin · Eastern Kirthar (Sindh)

Cited in 4 sources Last reviewed Jul 31, 2026

Unit summary

Rank: formation
Status: Published
Age: Cenozoic · Paleogene · Early EoceneLate Paleocene (to earliest Eocene)
Named by: Outerbridge et al (1989)
Type locality: Not recorded
Thickness: ~30 m
Lithology: Lateritic clay and mud with subordinate sandstone.
Synonyms: Not recorded

A lateritic clay unit at the base of the Eocene Laki Group, marking a weathering surface.

Named by Outerbridge et al. (1989) after the Sohnari member of HSC (1961) for the basal Laki laterite of Nuttall (1925), the Sohnari Formation consists of lateritic clay, ochre, shale, yellow arenaceous limestone, sandstone and lignitic coal. Its lower contact with the Lakhra Formation and upper contact with the Laki Formation are disconformable. It correlates with the Early Eocene Chamalang (Ghazij) Group and the Nammal Formation. Early Eocene.

Fossils

Not recorded

Contacts

In the Sindh Province column

LimestoneSandstoneIgneousShale / mudFossils 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

Sindh Province

Basin: Kirthar Basin
Region: Eastern Kirthar (Sindh)
Depositional environment: continental, paralic
Coordinates: Not recorded

Correlation

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

Economic significance

Not recorded

Remarks

The basal lateritic unit of the Eocene Laki Group in Sindh, recording subaerial weathering at the Paleocene–Eocene transition.

Research notes (4)

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)

Attested in Shah (2009), Geological Survey of Pakistan Memoir 22, which describes it as Sohnari Member of the Laki Formation (named with a designated type section in Shah 2009). Adds the definitional GSP/SCP lexicon citation.

Shah, S.M.I. (2009)

Age & correlation (1)

Kazmi & Abbasi (2008) CORRECTION: the Sohnari Formation (originally the Sohnari Member of the Laki Formation / basal Laki laterite, elevated to formation by Outerbridge 1989) is middle–late Paleocene, not Eocene as previously recorded (unsourced). Age corrected to Late Paleocene (passing up into the earliest Eocene Laki).

Kazmi, A.H. & Abbasi, I.A. (2008)

Thickness (1)

Thickness surfaced from the rank note: the Sonhari (Sohnari) unit is ~30 m of coal-bearing sandstone and lateritic clay of the Meting coal-field (Kazmi & Jan 1997, who treat it as the Sonhari Member of the Laki Formation).

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

Geological significance (1)

Kazmi & Jan (1997) RANK FLAG: the book describes this as the 'Sonhari Member' of the (Early Eocene) Laki Formation — ~30 m of coal-bearing sandstone and lateritic clay of the Meting coal-field, near the contact with the underlying Upper Paleocene Lakhra Formation — not as a stand-alone formation; deposited in brackish-water coastal swamps.

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

Sources (4)

Malkani, M.S. & Mahmood, Z. (2017). Stratigraphy of Pakistan. Geological Survey of Pakistan, Memoir Vol. 24.
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.

Reviewer confidence: medium

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). Sohnari Formation. In Pakistan Stratigraphy Dataset [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21363991

BibTeX

@misc{stratigraphypk_sohnariformation,
  author    = {Qudsi, Lareb},
  title     = {{Sohnari 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/sohnari-formation (accessed October 29, 2026).

To cite the unit's original definition instead, see: Outerbridge et al (1989).

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