Calcrete profiles in Puthukulam quarry section, Sathankulam region, Southern Tamilnadu, India: implications on palaeoclimate significance

Abstract

Calcrete is an impure limestone which is used as a substitute raw material resources for high-grade primary limestones like shell limestone, meta-sedimentary crystalline limestone in cement industries. They occur as a boundless deposit within the regolith profile sections rest over the basement rocks of granite quarry at Puthukulam Village, near Sathankulam region, Tuticorin District of Tamil Nadu, India. Geology of the area and schematic calcrete profiles stratigraphy are given. Field observation reveals that calcrete occurs as massive, laminated, oolitic, hardpan and lumpy forms in the study area. Micromorphological characters of calcrete of the area are revealing the displacive and replacive texture. And also the micritic and microsparitic calcite deposition is associated with regolith material. X-ray diffraction analysis reveals the general mineralogy and clay mineralogy of the calcrete. The major element geochemistry of calcrete through X-ray fluorescence spectrometry analysis (XRF) indicates that CaO, MgO, SiO2, Al2O3 and Fe2O3 are in a higher elevated concentration above 1% than other oxides, such as MnO, MgO, Na2O, K2O, TiO2 and P2O5. To evaluate the palaeoclimate significance, results of the proxies of mineralogy, clay mineralogy and major element geochemistry of calcrete are used.