Sedimentological Properties of the Sand Dunes and Valley Sediments in Al-Muthanna, Southern Iraq

Mohammed L Hussein

doi:10.46717/igj.54.1f.7ms-2021-06-27

Abstract

Sedimentological properties of the dunes and valley terrigenous sediments in Al-Muthanna Governorate, southern Iraq were carried out. Ten samples were collected, where five samples from both sand dunes, and valley sediments. Grain size analysis revealed that sand, silt and clay fractions are the constituents of these sediments. Sand fractions predominant in the dunes and the texture is classified as silty sand, whereas clay fractions dominate in the valley sediments, with sandy clay texture. The mineralogy is determined by X-ray diffraction, which revealed that quartz is the main mineral in both study areas, followed by calcite, feldspars in lesser amount and evaporates (gypsum) in minor component of the light minerals. Petrographically, monocrystalline quartz dominates over polycrystalline quartz in both areas. Rock fragments in the valley sediments are higher than in the sand dunes, which are comprised of carbonate, chert, igneous, metamorphic, evaporate, and mudstone rock fragments. Feldspars are approximately similar in the study areas and comprised mainly alkali feldspar (potash feldspar) and plagioclase. Petrogenically, the sand dunes occupy the quartzose-recycled field, while the valley sediments fall in transitional recycled fields represented recycled orogeny.

Highlights

The different quantities of quartz in both study areas attributed to a high amount of sand fractions, as well as multi rework operations of aerial transportation and sedimentation in the sand dunes compared to the valley filling sediments.Decrease of quartz in the valley sediments may related to the sand grain sizes, which are commonly fine due to abundance of clay- sized particles as indicated by high mud content in these sediments (Table 2, Figs. 4, 5, and 6)
The grain size analysis revealed that aeolian dynamic action of the sand dunes is higher than hydrodynamic one in the valley filling sediments
The sand dune sediments suffered multi recycled of weathering and transportation that caused reducing in unstable calcite and carbonate rock fragments.These processes effect on concentration of other rock fragments constituent in the sand dunes

Summary

Introduction

Sand covers 20% of the earth’s deserts, while deserts cover approximately 20% of the earth’s surface (Watson, 1997). The sand, which was generated by erosion of rock, containing quartz, feldspar, in addition to other hard minerals (Pye and Toser, 2009). Iraqi Mesopotamian Plain for the past four decades had been, and still, suffered from desertification, in which vast agricultural areas are transformed into sand dune fields. The valleys are among the most common Quaternary deposits in the study area. They consist of soft sedimentary deposits, or sandy and silty gravel in the main and deep valleys. The thickness of these deposits is not more than one meter. It is still partially active, and the depositional environment of these sediments is riverine

Methods

Results

Conclusion