Paleozoic • Devonian–Carboniferous formation In GSP lexicon

Ali Masjid Formation

Late Devonian to Early Carboniferous (early Frasnian to mid-Tournaisian)

Northern Indus Suture

Devonian–Carboniferous in the time scale →

Cited in 7 sources Last reviewed Aug 10, 2026

Unit summary

Rank: formation
Status: Published
Age: Paleozoic · Devonian–Carboniferous · Late Devonian–Early Mississippian (Tournaisian)Late Devonian to Early Carboniferous (early Frasnian to mid-Tournaisian)
Named by: Stauffer (1968)
Type locality: Ali Masjid village, Khyber Pass34.0800°N, 71.2900°E
Thickness: 220 m
Lithology: Red shale alternating with siltstone, sandstone, quartzite and limestone, with thin conglomerates and lateritic beds marking repeated breaks in sedimentation.
Synonyms: Ali Masjid Group

A Late Devonian red-shale-and-sandstone unit of the Khyber Pass, between the Shagai and Khyber limestones.

The Ali Masjid Formation is a Late Devonian to Early Carboniferous (early Frasnian to mid-Tournaisian) unit of the Khyber Pass area, named after Ali Masjid village and extending across the Khyber Agency (Kazmi & Jan 1997). It consists of red shale alternating with siltstone, sandstone, quartzite and limestone, with thin conglomerates and lateritic beds marking repeated breaks in sedimentation; its age is tightly constrained by conodont faunas (Molloy, Talent & Mawson 1997). Khan et al. (1989) had earlier grouped it, with the Landikotal Slates, in the Shagai Formation.

Fossils

Brachiopods Corals Conodonts (Famennian–Tournaisian zonal fauna)

Contacts

In the Khyber–Nowshera Belt column

Shale / mudMetamorphicLimestoneFossils 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

Khyber–Nowshera Belt

Basin: Northern Indus Suture
Region: Not recorded
Depositional environment: marine, marginal marine
Coordinates: 34.0800°N, 71.2900°E

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Correlation

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

Economic significance

Not recorded

Remarks

A red-bed unit extending across the Khyber Agency; thin conglomerates and laterites record repeated breaks in sedimentation, and fossiliferous beds west of the type section yield a Late Devonian brachiopod-and-coral fauna. It is correlated with the Haji Gak Formation of Afghanistan.

Research notes (6)

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 (2)

Merged the redundant "Ali Masjid Group" (ali-masjid-group) into this record; old name kept as a synonym.

Malkani, M.S. & Mahmood, Z. (2017)
Attested in Shah (2009), Geological Survey of Pakistan Memoir 22 - the Stratigraphic Committee of Pakistan's compiled lexicon (listed in the memoir's contents). Adds the definitional GSP/SCP lexicon citation.

Shah, S.M.I. (2009)

Age & correlation (3)

Kazmi & Jan (1997): the Ali Masjid Formation (type locality the village of Ali Masjid, Khyber Pass; extends across the Khyber Agency) is Late Devonian on a brachiopod and coral fauna — 220 m of red shale alternating with siltstone, sandstone, quartzite and limestone, with thin conglomerates and lateritic beds marking breaks in sedimentation. It conformably overlies the Shagai Limestone and is conformably overlain by the Khyber Limestone; Shah (1977) correlated it with the Haji Gak Formation of Afghanistan. Corroborates the curated Late Devonian age.

Kazmi, A.H. & Jan, M.Q. (1997)
Molloy, Talent & Mawson (1997): conodonts (62 species/subspecies) from acid-leaching of 226 samples across four measured sections through the Ali Masjid Formation west of Misri Khel (former South Khyber Agency) show the unit spans at least the Middle crepida Zone (low Famennian) up to the Early crenulata Zone (mid-Tournaisian), with a fauna low in one section indicative of the Late falsiovalis Zone (early Frasnian). The formation therefore ranges from the early Late Devonian INTO the Early Carboniferous (Tournaisian), refining the curated 'Late Devonian'. Two hiatuses are inferred (between the Late falsiovalis and Middle crepida zones, and between the Late expansa and Early duplicata zones). It conformably overlies the Shagai Limestone and is overlain (transgressively) by the Carboniferous–Permian Khyber Limestone; the map legend of Stauffer (1968a) gives its range as ?Givetian–Tournaisian.

Molloy, P.D., Talent, J.A. & Mawson, R. (1997)
Kazmi & Abbasi (2008) COMPETING INTERPRETATION (not applied): the book notes views that reassign the Khyber carbonates (including the Ali Masjid Formation) to the Precambrian (Aslam 2000; Pogue et al. 1999) and even questions the unit's validity (Khan 1989 read it as a slumped Khyber-Limestone block). The curated Late Devonian–Early Carboniferous age is retained because it rests on the hard conodont biostratigraphy of Molloy, Talent & Mawson (1997); the Precambrian reassignment is recorded as an unresolved alternative.

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

Fossils & biostratigraphy (1)

Pogue, Harris & Hussain (1992): conodonts (Icriodus, Palmatolepis aff. gracilis plexus, Polygnathus extralobatus, P. perplexus) from crinoidal limestone overlying the Ghundai Sar reef complex indicate a Late Devonian (Famennian, expansa Zone) age for the Ali Masjid Formation - corroborating the curated Late Devonian age with independent conodont control.

Pogue, K.R., Harris, A.G. & Hussain, A. (1992)

Sources (7)

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.
OpenStreetMap contributors and GEOnet Names Server (public geographic gazetteers), used to geolocate named GSP type localities to approximate decimal coordinates.
Shah, S.M.I. (2009). Stratigraphy of Pakistan. Geological Survey of Pakistan, Memoir Vol. 22.
Molloy, P.D., Talent, J.A. & Mawson, R. (1997). Late Devonian-Tournaisian conodonts from the eastern Khyber region, north-west Pakistan. Rivista Italiana di Paleontologia e Stratigrafia, 103(2), 123-148.
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.
Pogue, K.R., Harris, A.G. & Hussain, A. (1992). Paleozoic and Mesozoic stratigraphy of the Peshawar basin, Pakistan: Correlations and implications. Geological Society of America Bulletin, 104(8), 915-927.

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

BibTeX

@misc{stratigraphypk_alimasjidformation,
  author    = {Qudsi, Lareb},
  title     = {{Ali Masjid 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/ali-masjid-formation (accessed October 7, 2026).

To cite the unit's original definition instead, see: Stauffer (1968).

Below · older

Shagai Limestone

Silurian–Devonian

Above · younger

Khyber Limestone

Carboniferous–Permian