Sedimentology, Mineralogy of Al-Dujaila River Sediments Project, Southeastern Kut City, Iraq

Abstract

A sedimentological and mineralogical study was carried out on sediments of Al-Dujaila River Project, one of the branches of the Tigris River, southeastern Kut City, Iraq. The study aims to identify the nature and maturity of sediments in order to deduce the provenance of these sediments and the source area. The results of grain size analysis of ten river sediment samples indicated that the averages are: silt (44.97%), clay (34.06%), and sand (20.96%). According to Folk's classification (1974), the sediments are classified as sandy mud. A microscopic study of five sand fraction samples has shown the presence of light and heavy minerals. Light minerals (average 94.6%) include on average: a major share of rock fragments (64.8% including dominant carbonate, chert, igneous, metamorphic, and mudstone), quartz (24.1% including dominant monocrystalline and polycrystalline), feldspars (5% including orthoclase and plagioclase) while evaporates, and coated clays are subordinate. Heavy minerals (average 5.4 %) include opaques (average 54.2%) and non-opaques (average 45.8%) including pyroxene, amphibole, epidote, garnet, staurolite, chlorite, biotite, muscovite, zircon, tourmaline and rutile. Based on the mineralogical signatures, light and heavy minerals reflect metamorphic, mafic and felsic igneous rocks of the active margin of the unstable shelf in addition to carbonate, evaporate and mud of sedimentary rocks that could be sourced from the floodplain. According to sediment diversity and very poor grain sorting in the study area, as well as the values of indices of mineral maturity MI (0.34), MMI (0.76), and the ZTR (23.5%), all these results indicate that sediments are immature to extremely immature, which means the source area represents rather elevated topography, rapid erosion and transport in arid to the semi-arid environment and a short distance of transportation. The tectonic provenance of Al-Dujaila River sediments can be characterized as a lithic reworked of the recycled orogen as a result of the collision range of Taurus and Zagros Mountain range.