Open AccessPetrography, geochemistry and depositional model of Ispikan Conglomerate, Makran Accretionary Prism, Southwest Pakistan
Author(s) -
Muhammad Ahmed Farooqui,
Khalil Ur Rehman,
Amir Yaseen,
Ghazala Roohi,
Muhammad Umar
Publication year - 2021
Publication title -
maǧallaẗ al-kuwayt li-l-ʿulūm
Language(s) - English
Resource type - Journals
eISSN - 2307-4116
pISSN - 2307-4108
DOI - 10.48129/kjs.v49i1.10486
Subject(s) - conglomerate , geology , petrography , provenance , accretionary wedge , geochemistry , sedimentary depositional environment , detritus , lithic fragment , arenite , clastic rock , metamorphic rock , sedimentology , siliciclastic , siltstone , petrology , sedimentary rock , paleontology , facies , subduction , structural basin , tectonics
Sedimentology, petrography, and geochemistry of the Ispikan Conglomerate of southwest Makran have been studied to establish its stratigraphic position, age, provenance, and depositional environment. Very thin to massive beds, poor sorting, no fabric, and poor grading are the common features. It is composed of mostly reworked, medium- to coarse-grained pebbly sandstone, siltstone, and discontinuous lenses of matrix- and clast-supported conglomerate. The sandstone is composed of angular to sub-angular, poorly sorted, immature grains having Q72F13L15 as average composition. Pebbles are of mostly metamorphic and acidic igneous origin. Large angular boulders (~1.5m) of sandstone indicate quick debris flow conditions. Geochemical discriminants suggest the derivation of Ispikan sediments from an active continental margin. The Nb and Zr/Th and Ba/Y values indicate the continental island arc setting, whereas a high K/Rb ratio points to the derivation of detritus from an acid and intermediate source. Ispikan Conglomerate is interpreted as an Eocene olistostrome formed after a localized submarine debris flow triggered by slope failure.