Mesozoic • Jurassic formation Literature

Darwaz An Formation

Early Jurassic (Pliensbachian)

Karakoram-Hindukush Basin · Central Karakoram Batholith

Cited in 2 sources Last reviewed Jul 31, 2026

Unit summary

Rank: formation
Status: Published
Age: Mesozoic · Jurassic · Early Jurassic (Liassic)Early Jurassic (Pliensbachian)
Named by: Zanchi & Gaetani (2011)
Type locality: Dark grey limestone strip just east of the Darwaz Pass (Darwaz An), upper Yarkhun Valley, between the top of the Ailak Formation and the overthrusting Devonian Chilmarabad dolostones; the only dated Jurassic succession identified in the upper Yarkhun Valley.
Thickness: preserved thickness slightly less than 100 m
Lithology: At the base, a few metres of thin grey-brown sandstones (locally present), overlain by medium-bedded grey limestone (wackestone to packstone) with seams of fragmentary bivalves, layers of turriculate gastropods and foraminifers; the upper part is medium- to thick-bedded recrystallized limestone spectacularly crowded with large to giant bivalves (up to 40 cm), including pernids and ostreids (some resembling Mytiloperna sp.) in Lithiotis-facies.
Synonyms: Not recorded

The Darwaz An Formation is an Early Jurassic (Pliensbachian) carbonate lens exposed just east of the Darwaz Pass in the upper Yarkhun Valley — the only dated Jurassic succession there. Basal transgressive grey-brown sandstones pass up into grey wackestone–packstone and recrystallized limestone crowded with large to giant bivalves (pernids and ostreids) of the Lithiotis-facies, deposited in a confined lagoon within the Karakoram carbonate platform. It rests transgressively on the Ailak Formation and is overthrust by the Devonian Chilmarabad dolostones.

Fossils

Large to giant bivalves (pernids, ostreids; Lithiotis-facies)Turriculate gastropodsThaumatoporella parvovesiculiferaAmijiella amijiPseudocyclammina liasicaSiphovalvulina variabilisPlaninvoluta carinata

Contacts

Lower contact — unconformable; upper contact — faulted.

In the Hindukush-Chitral column

LimestoneConglomerateSandstoneShale / mudFossils recordedUnconformityConformable

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

Hindukush-Chitral

Basin: Karakoram-Hindukush Basin
Region: Central Karakoram Batholith
Depositional environment: carbonate platform, restricted, confined lagoon
Coordinates: Not recorded

Correlation

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

Economic significance

Not recorded

Remarks

A Pliensbachian (Early Jurassic) confined-lagoon carbonate lens within the wider Karakoram platform; its basal sandstones form the transgressive tract of a sequence resting on the emerged Ailak dolostones. Assigned to the Lithiotis-facies (foraminiferal microfacies with Amijiella amiji and Pseudocyclammina liasica), and the only dated Jurassic unit in the upper Yarkhun Valley — it helps bracket Cimmerian deformation in the Baroghil area between the latest Triassic and the Pliensbachian.

Sources (3)

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

APA

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

BibTeX

@misc{stratigraphypk_darwazanformation,
  author    = {Qudsi, Lareb},
  title     = {{Darwaz An 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/darwaz-an-formation (accessed September 5, 2026).

To cite the unit's original definition instead, see: Zanchi & Gaetani (2011).

Below · older

Ailak Formation

Triassic