Provenance Analysis of Injana and Mukdadiya Formations (Miocene/Pliocene) in Duhok Governorate, Northern Iraq

Abstract

This study deals with the petrography and heavy mineral analysis of Injana (Upper Fars) and Mukdadiya (Lower Bakhtiari) Formations in Zakho and Amadiya areas, Duhok Governorate. A total of 58 samples are collected from Injana and Mukdadiya Formations representing: sandstone (21 samples from Injana Formation and 30 samples from Mukdadiya Formation), mudstone (5 samples from Mukdadiya Formation) and conglomerate (2 samples from Mukdadiya Formation). 37 samples of sandstone are thin sectioned for petrographic study (16 thin sections from Injana and 21 thin sections from Mukdadiya) and 40 sandstone samples are selected for heavy minerals study (17 samples from Injana and 23 samples from Mukdadiya). Also 5 samples of oriented mounts mudstone from Mukdadiya for X-ray diffraction and 2 samples of conglomerate from Mukdadiya are classified. The gravel analysis revealed that the gravel of Mukdadiya Formation in both sections (Amadiya and Zakho) is composed mainly of sedimentary and igneous gravel, as well as metamorphic gravel in small amount. That indicates it's derived manly from sedimentary and igneous sources mainly and less metamorphic sources. The petrographic investigations revealed that the sandstone of Injana and Mukdadiya Formations are composed primarily of rock fragments (sedimentary, igneous and metamorphic), quartz grains (monocrystalline and polycrystalline), and feldspars (orthoclase, microcline, perthite and plagioclase). These components are bound by carbonate cement. The percentage of quartz grains in Injana Formation is more than the percentage of quartz in Mukdadiya Formation, and the percentage of rock fragments in Injana is less than the percentage of rock fragments in Mukdadiya sandstone. The suggested provenance for the concerned Injana and Mukdadiya Formations are primarily sedimentary and igneous rocks and the less dominant metamorphic rocks. These sandstones are classified as Litharenites and mineralogically immature. X-ray diffraction analysis for the mudstone unit of Injana and Mukdadiya Formations at Zakho sections shows that the clay minerals are: montmorillonite, illite, and kaolinite. These minerals refer to that it derived mainly from acidic igneous and sedimentary and less dominance metamorphic and ultrabasic igneous source rocks, it is also referring arid to semi-arid climate. The heavy minerals assemblages include opaque minerals as major component, epidotes, garnet, amphiboles, clinopyroxenes, orthopyroxenes, chromian spinal, zircon, tourmaline, rutile, chlorite, biotite, muscovite and others (kyanite and staurolite). These assemblages indicate that the heavy minerals are derived from mafic igneous and metamorphic rocks mainly as well as acidic igneous and reworked sediments. The tectonic provenance for Injana and Mukdadiya Formations can be described as recycled orogen