Thermal Characteristics of the Near-Surface Playa Sediments from the Thar Desert, Rajasthan

The playas located in the semi-Arid to arid western Rajasthan, Thar Desert, India host a variety of evaporites and detrital minerals. The focus of the present study is to address the mineralogical and thermal characteristics of the Near-surface playa sediments from six different playas scattered in different climatic zones of the desert. Based on the results of differential thermal analysis (DTA), Thermo-Gravimetry (TG), X-ray diffractometry (XRD) and carbon analysis (CSA, CWA), the playas are divided into two different groups. The sediments from the first group consisting of Phulera, Sambhar, Didwana, and Bap-Malar playas are characterised by the presence of relatively higher abundance of organic carbon (C_org), Fe-Bearing Proto-Bolomite and indicate a relatively reducing environment of deposition. The presence of hematite in the sediments from second group comprising of Pokhran and Pachapadra playas indicate a relatively oxidising environment. The absence of sulphate mineral, gypsum in the sediments of the first group of playas is more speculative and might be caused by organic carbon reducing the sulphates or by bacterial activity in the Hyper-Saline environment.