Structural Inferences from Radiometric Surveys in and around Ramadugu Lamproite Field, NW margin of the Cuddapah basin, Eastern Dharwar craton

An attempt has made to map radiometric intensity over a part of the Ramadugu, Vattikod, and Somvarigudem lamproite fields of Nalgonda District, Telangana State, North Western margin of the Cuddapah basin and their relationship with geological structures and tectonics. Interpretation of radiometric data brought out the structural features, trends, faults and contacts corresponding to the lithological formations observed in the area. The formations are amphibolites, schists, biotite gneisses, granites, granodiorites and dolerites. They are qualitatively inferred from the radiometric map, which may enable more precise geological mapping of these formations. A geological map of the study area with observed radioactivity of each formation is presented. The corresponding radioactivity for amphibolites, schist, biotite gneiss, granites, granodiorite, quartz vein and dolerites are 23.15 mu R/hr (22.87 mu R/hr to 23.4 mu R/hr), 22.77 mu R/hr (20.94 mu R/hr to 24.8 mu R/hr), 27.69 mu R/hr (20 mu R/hr to 37.05 mu R/hr), 25.62 mu R/hr (24.77 mu R/hr to 27.7 mu R/hr), 20.85 mu R/hr (15.69 mu R/hr to 23 mu R/hr) and 26.5 mu R/hr (12.38 mu R/hr to 40.71 mu R/hr), respectively. A low radioactivity has been registered over Ramadugu lamproite field (18.25 mu R/hr to 21.58 mu R/hr) and Yacharam lamproites field (19.91 mu R/hr to 20.41 mu R/hr), Vattikod lamproites field 25.56 mu R/hr to 27.82 mu R/hr) and Somavarigudem lamproites field (17.38 mu R/hr to 18.13 mu R/hr). Coefficient of variation values calculated for the radiometric data revealed seven deep-seated faults (F1 to F7), two running NW-SE, three NE-SW, one N-S and one another NNW-SSE. In addition, radiometric data revealed in the region disposition of schist belts, various faults and other lineaments /dykes and contact between granite gneiss and dolerite dykes.