Chalt Volcanic Group
Mid-Cretaceous (pre-suturing)
Kohistan Arc · Northern Greenstone Belt
Cretaceous in the time scale →Cited in 5 sources Last reviewed Aug 20, 2026
- 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.
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
- 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.
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.
Cite this unit
Qudsi, L. (2026). Chalt Volcanic Group. In Pakistan Stratigraphy Dataset [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21363991
@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 September 5, 2026).
To cite the unit's original definition instead, see: Petterson et al. (1990); Treloar et al. (1996).
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