Petrography, geochemistry and depositional model of Ispikan conglomerate, Makran accretionary prism, southwest Pakistan

Abstract EN

Depositional environments, provenance and tectonic settings of Ispikan group exposed in south west Makran, were revealed by lithofacies, petrography and geochemistry studies.

The group is consisting of conglomerate, very coarse-pebbly sandstone with subordinate fine grained sediments.

The conglomerates were dominated by igneous, sedimentary (limestone and sandstone) and metamorphic rocks fragments.

The sandstone is texturally immature.

The petrographic study exhibits that the sediments were sourced from cratone interior, quartzose, transitional recycled orogens, collision suture & fold-thrust belt and subduction complex sources.

The igneous fragments were felsic to intermediate nature as reflected by higher values of K/Rb.

Geochemical discriminants suggest the Ispikan sediments to have been derived from an active continental margin.

The Continental Island arc was intimated by value of Nb, Ba/Y and Zr/Th.

The Makran Accretionary Prism was tectonically active site for the deposition of debris flow related olistrostromes of Ispikan conglomerates in submarine environments.