Mesozoic • Cretaceous group Literature

Chalt Volcanic Group

Mid-Cretaceous (pre-suturing)

Kohistan Arc · Northern Greenstone Belt

Cited in 5 sources Last reviewed Aug 20, 2026

Unit summary

Rank: group
Status: Published
Age: Mesozoic · CretaceousMid-Cretaceous (pre-suturing)
Named by: Petterson et al. (1990); Treloar et al. (1996)
Type locality: Hunza Valley and nearby valleys, northern Kohistan (Chalt area).
Thickness: Not recorded
Lithology: A relatively thick, lava-dominated accumulation of high-Mg (MgO 6-15%) tholeiitic volcanic rocks — Mg-basalt to Mg-andesite and boninite (boninitic Si/Mg/Cr/Ni/Ti/Zr signatures, negative Nb anomalies, high LILE/HFSE), bimodal with volumetrically minor rhyolites; strongly deformed with stretched pillows.
Synonyms: Chalt Volcanics

The Chalt Volcanic Group is a mid-Cretaceous, pre-suturing accumulation of high-Mg volcanic rocks in the Hunza and nearby valleys of northern Kohistan (the Chalt Volcanics sensu stricto of Petterson et al. 1990). It ranges from high-Mg basalt/basaltic komatiite to high-Mg andesite and boninite, with subduction-related trace-element patterns, and marks the thermal climax of the first intra-arc/back-arc rifting phase. NOTE: this is a Kohistan arc unit, distinct from the Karakoram Chalt Formation.

Fossils

Not recorded

Contacts

Lower contact — conformable; upper contact — not recorded.

In the Kohistan Arc column

IgneousConglomerateFossils recordedIntrusiveContact not recordedConformable

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

Kohistan Arc

Basin: Kohistan Arc
Region: Northern Greenstone Belt
Depositional environment: volcanic-arc, marine
Coordinates: Not recorded

Correlation

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

Economic significance

Not recorded

Remarks

High-Mg/boninitic magmatism from decompression melting of depleted mantle at the peak of the first Kohistan extensional (intra-arc to back-arc rift) event; overlies the Jaglot Group and is overlain by the Albian-Aptian Yasin Group. On the revised map the formerly-lumped 'Western Volcanics' are reassigned to the Eocene Shamran Volcanic Group.

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.

Lithology (2)

Coward et al. (1984): the Chalt Group forms the northern crust of the Kohistan arc, south of the northern suture - metagreywackes and slates, epidotic grits and tuffs, hornblende-bearing tuffs, chlorite schists, schistose amphibolites, amygdaloidal pillow-bearing basalts and fragmental basic volcanics, several kilometres thick (partly by fold/thrust repetition), folded by large upright tight-to-isoclinal folds and cut by thin granitic dykes and muscovite pegmatites.

Coward, M.P., Jan, M.Q., Rex, D., Tarney, J., Thirlwall, M. & Windley, B.F. (1984)
Petterson (2010): the Chalt Volcanic Group is the northernmost Kohistan-wide conformable unit (~330 km E-W by up to 30 km N-S), a high-Mg tholeiitic (with boninitic affinity) lava-dominated intra-oceanic-arc pile intruded to the south by the Kohistan batholith; Petterson & Windley (1985) characterise the Chalt volcanics as basaltic tholeiites. Primary sources for the CVG lithology and tectonic setting.

Petterson, M.G. (2010)

Sources (4)

Treloar, P.J., Petterson, M.G., Jan, M.Q. & Sullivan, M.A. (1996). A re-evaluation of the stratigraphy and evolution of the Kohistan arc sequence, Pakistan Himalaya. Journal of the Geological Society, London, 153, 681-693.
Treloar, P.J., Petterson, M.G., Jan, M.Q. & Sullivan, M.A. (1996). A re-evaluation of the stratigraphy and evolution of the Kohistan arc sequence, Pakistan Himalaya: implications for magmatic and tectonic arc-building processes. Journal of the Geological Society, London, 153, 681-693.
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.
Coward, M.P., Jan, M.Q., Rex, D., Tarney, J., Thirlwall, M. & Windley, B.F. (1984). Geology of the South Central Karakoram and Kohistan. In: Miller, K.J. (ed.), The International Karakoram Project, Vol. 2, 71-84. Cambridge University Press.

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: Defined in journal or other literature; not found in a GSP memoir. There is no body currently ratifying unit status, so provenance is shown in place of a formal ruling.

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Cite this unit

APA

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

BibTeX

@misc{stratigraphypk_chaltvolcanicgroup,
  author    = {Qudsi, Lareb},
  title     = {{Chalt Volcanic Group} --- 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/chalt-volcanic-group (accessed October 29, 2026).

To cite the unit's original definition instead, see: Petterson et al. (1990); Treloar et al. (1996).

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