Genesis, Morphology And Geochemistry Of Calcretes Formed In Stabilised Sand Dunes Of Bathinda and Rajasthan

Abstract

Ground water level and chemistry, rain fall intensity, climate type, supply of wind borne dust rich in calcium carbonate influences the formation of calcretes in dune profiles. Study of calcrete will help to understand the paleoclimate, vegetation and provenance of sediments where it developed. In this study calcretes were collected from Bathinda and Rajasthan. Morphological types, size measurement, CaCO3 percentage, mineralogical and geochemical analysis were investigated on the calcrete sample. Result shows calcite, quartz, and anorthite are major mineral phases found in the calcretes. A majority of the samples are tubular types (both having hollows i.e. rhizoliths and as well as no hollows). Indurated to very soft type calcrtes also found in these areas. CaCO3 percentage in the calcretes is higher than the dune sediments. SEM and EDX data says that the cementing materials are calcites and the grains are quartz along with some clay fractions. Two types of calcite cement, micritic and sparitic are are observed. Geochemical analysis suggest that the trace elements such as Co, Ni, As, Th and U show positive correlation with CaCO3 percentage.