Paleozoic • Silurian formation GSP memoir

Owsi Nala Limestone

Middle to Late Silurian

Northern Indus Suture

Cited in 2 sources Last reviewed Jul 31, 2026

Unit summary

Rank: formation
Status: Published
Age: Paleozoic · SilurianMiddle to Late Silurian
Named by: Not recorded
Type locality: Owsi Nala, Khyber area
Thickness: ~30 m
Lithology: Limestone with shale intercalations.
Synonyms: Not recorded

A Silurian limestone-and-shale unit of the Khyber area at Owsi Nala.

Owsi Nala limestone consists of limestone and shale intercalations. Mafic intrusions produced soapstone lenses. On the basis of superposition age is Middle to upper Silurian age (Khan, M.A. 1970). Kandar phyllite consists of phyllite, phyllitic schists interbedded with limestone and mafic sills which have produced soapstone. Middle to upper Silurian (Khan, M.A. 1970).

Fossils

Not recorded

Contacts

In the Khyber–Nowshera Belt column

LimestoneMixedMetamorphicContact 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

Khyber–Nowshera Belt

Basin: Northern Indus Suture
Region: Not recorded
Depositional environment: marine
Coordinates: Not recorded

Correlation

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

Economic significance

Not recorded

Remarks

A Silurian limestone-and-shale unit of the Khyber area.

Research notes (2)

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

Age & correlation (1)

Kazmi & Abbasi (2008): the Owsi (spelled 'Oosi') Nala Limestone is Unit 2 of Khan M.A.'s (1970) Ali Masjid Group in the Ghundai Sar area, Khyber Agency — 30 m of light grey lithographic limestone with shale interbeds and large angular clasts from the underlying Spin Rag Quartzite (soapstone lenses where mafic intrusions occur), unfossiliferous; a Middle to Upper Silurian age is inferred from superposition. Conformably overlies the Spin Rag Quartzite and is conformably overlain by the Kandar Phyllite. Refines the curated 'Silurian'.

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

Thickness (1)

Thickness surfaced from the age note: the Owsi (Oosi) Nala Limestone is 30 m of light-grey lithographic limestone with shale interbeds (Kazmi & Abbasi 2008).

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

Sources (2)

Malkani, M.S. & Mahmood, Z. (2017). Stratigraphy of Pakistan. Geological Survey of Pakistan, Memoir Vol. 24.
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: Appears in a single-author Geological Survey of Pakistan memoir (Malkani & Mahmood 2017), not cross-confirmed against the Shah lexicon. The Stratigraphic Committee of Pakistan is largely inactive, so documented provenance — not formal ratification — is the available signal.

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Cite this unit

APA

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

BibTeX

@misc{stratigraphypk_owsinalalimestone,
  author    = {Qudsi, Lareb},
  title     = {{Owsi Nala Limestone} --- 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/owsi-nala-limestone (accessed October 29, 2026).