Cenozoic • Paleogene

Siahan Formation

Eocene-Oligocene

Stratigraphic position

In the Makran Coast column

SandstoneShale / mudLimestoneFossils 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.

A Paleocene–Eocene deep-sea shale (locally slate) of the Makran wedge, the muddy partner to the Panjgur sandstones.

Deep marine turbidite sequence in Makran accretionary prism. Part of the arc-trench gap fill.

Significance. A Paleocene–Eocene flysch shale (locally slate) of the Makran accretionary wedge; with the Hoshab shale it forms the fine-grained, valley-forming part of the Khojak–Panjgur submarine-fan system.

Lithology: Shale and slate with siltstone and sandstone (metamorphosed near the Washuk ophiolite thrust).
Thickness: 2000-4000 m
Type locality: Siahan Range
Environment: deep marine
Introduced by: HSC (1961)

Fossils

Deep water foraminiferaTrace fossils

Provinces

Makran Coast

References

Malkani, M.S. & Mahmood, Z. (2017). Stratigraphy of Pakistan. Geological Survey of Pakistan, Memoir Vol. 24.
Cromie, P. et al. (2022). Tectonostratigraphic Evolution and Hydrocarbon Prospectivity South of Gwadar Bay, Makran Accretionary Wedge, Offshore SW Pakistan. (petroleum-system study).

Reviewer confidence: medium

Related units

Below · older

Wakai limestone

Paleogene

Above · younger

Zurati formation

Paleogene