Weathering indices and mineralogical composition of the sand fraction in soils from the western desert of holy Karbala governorate, Iraq

This study focuses on analyzing the mineral composition of sand fraction was separated from clay and silt in selected soils of the Western Desert in Karbala Governorate, Iraq, and assessing the intensity of Mineral Weathering Index MWI and ZTR indicators. Sixteen samples were collected from depths of 0–30 cm, sand was separated from clay and silt, then light and heavy minerals were identified with polarized light microscope. The results showed that monocrystalline quartz dominated by 21.1-26.9%, while polycrystalline quartz ranged between 2.7–4.6%. Feldspar content ranged 2-3.9%, and carbonate rock fragments accounted for 28.2–40.2%. Heavy minerals were the most abundant which resented by iron oxides at 39.5-47.7%. Chlorite is present with 7.8-10.1%, biotite mica 4.4-6.5%, and muscovite 4.9–6.9%. Unstable minerals such as pyroxene and amphiboles ranged from 3.4–6.8%. MWI values ranged from 0.33-0.44, and ZTR values between 21.1-26.9, moderate to low weathering and low to moderate mineral maturity. These results reflect the nature of sedimentary deposits and the impact of a dry desert environment on limited chemical weathering.