Geological Setting

Abstract

This chapter deals with the geological and tectonic framework around the thermal springs. The springs are traced to occur along tectonic zones and in the absence of any active volcano, Odishan springs can only claim to be controlled by tectonic factor. These springs are either located in Gondwana graben or intersection of lineaments of Precambrian terrain. The rock assemblages around the thermal springs belong to the Iron Ore Supergroup, Easternghat Supergroup or Vindhyan Supergroup depending on their location as superimposed on the geology of the state. While the quartzites of Iron Ore Supegroup are traced around Magarmuhan and Bankhol region, khondalite, charnockite, augen-gneiss (granitic) are the litho-types encountered near the thermal springs at Attri, Tarabalo, Taptapani and Deuljhori. The rocks have suffered highest grade of regional metamorphism and are intricately folded and belong to Precambrian age. These Precambrian rocks are repository of radioactive minerals and possibly have led to increase radioactivity. Mineralogy of these rocks is discussed. The special features of the rocks of Gondwana Supegroup in so far as they control the different parameters of thermal springs are described and discussed. The rock types and their mineralogical composition are important as they play their roles during the percolation of meteoric water through them.