Yashkuk Formation
Jurassic
Karakoram-Hindukush Basin · Central Karakoram Batholith
Jurassic in the time scale →Cited in 7 sources Last reviewed Jul 30, 2026
- Rank
- formation
- Status
- Published
- Age
- Mesozoic · Jurassic · Early Jurassic (Middle–Late Liassic)Jurassic
- Named by
- Gaetani et al. (1990a)
- Type locality
- Yashkuk, confluence of the Chapursan River and Yashkuk Yaz glacier, upper Hunza36.8163°N, 74.3667°E
- Thickness
- about 150 m (basal ~2 m polymictic conglomerate overlain by shale, siltstone and molassic red sandstone)
- Lithology
- A lower unit of fine-grained, reddish, cross-laminated and ripple-marked sandstone with mud cracks and raindrop prints, overlain by pelite, marly limestone, oolitic calcarenite and oncoidal/cherty limestone.
- Synonyms
- Not recorded
An Early Jurassic unit that passes up from river-laid red sandstones into shallow-marine limestones, above the Ashtigar Formation.
Yashkuk formation is named after Yashkuk village at the confluence of Chapursan River and Yashkuk Yaz glacier by Gaetani et al. (1990a) for reddish sandstone with many sedimentary structures. It is middle to upper Liassic. The Mesozoic terrestrial strata of Karakoram (for example Fig.6) are significant for the exploration of Mesozoic vertebrates for Paleobiogeographic link. Pakistan is lucky to include both Laurasian and Gondwanan blocks along with Tethyan deposits.
Fossils
Contacts
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
- Basin
- Karakoram-Hindukush Basin
- Region
- Central Karakoram Batholith
- Depositional environment
- fluvial, shallow marine
- Coordinates
- 36.8163°N, 74.3667°E
Correlation
Not recorded. Compare this unit against other basins on the correlation panel →
Economic significance
Not recorded
Remarks
A Middle to Upper Liassic (Early Jurassic) unit recording a shift from a fluvial meander-belt setting in its lower red-bed part to an open-lagoon marine transgression in its upper carbonate part; it overlies the scoured top of the Ashtigar Formation.
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 - 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 (2)
-
Gaetani et al. (2013): the base of the Yashkuk Formation is dated as Pliensbachian (Early Jurassic; Gaetani et al. 1993), consistent with the curated Early Jurassic assignment. Its basal erosional contact and gentle angular unconformity seal the mildly folded Ashtigar shale, so the molassic Yashkuk clastics bracket Cimmerian deformation between the latest Triassic and the Pliensbachian.
-
Zanchi & Gaetani (2011): the Yashkuk Formation is Toarcian–Aalenian (Gaetani et al. 1993), its base dated to the latest Pliensbachian; introduced by Gaetani et al. (1990a). Fine-grained red and green litharenites, siltstones and shales, 10–300 m thick, deposited on continental distal alluvial fans recording dismantling of the Cimmerian orogenic belt.
Type locality & location (1)
-
Type-locality coordinate set from reviewer-supplied GPS (36.816267 N, 74.366690 E), Chapursan valley, upper Hunza.
Sources (6)
- 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.
- Gaetani, M., Nicora, A., Henderson, C., Cirilli, S., Gale, L., Rettori, R., Vuolo, I. & Atudorei, V. (2013). Refinements in the Upper Permian to Lower Jurassic stratigraphy of Karakorum, Pakistan. Facies, 59, 915-948.
- Zanchi, A. & Gaetani, M. (2011). The geology of the Karakoram range, Pakistan: the new 1:100,000 geological map of Central-Western Karakoram. Italian Journal of Geosciences, 130(2), 161-262.
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.
Cite this unit
Qudsi, L. (2026). Yashkuk Formation. In Pakistan Stratigraphy Dataset [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21363991
@misc{stratigraphypk_yashkukformation,
author = {Qudsi, Lareb},
title = {{Yashkuk 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/yashkuk-formation (accessed October 29, 2026).
To cite the unit's original definition instead, see: Gaetani et al. (1990a).
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