Himalayan Geology, Vol. 42 (2), 2021, pp. 299-311, Printed in India
Structural mapping and Mineral Potential of Deoban Group, Tons Valley, Kumaun Lesser Himalaya
DINESH S. CHAUHAN1*, P.K. GAUTAM2, S.K. TRIPATHI3
1Geological Survey of India, Dehradun
2Geological Survey of India, Lucknow
3Geological Survey of India, Hyderabad
*Email (Corresponding author): dinesh_geo@rediffmail.com
Abstract: Deoban Group is Meso-Proterozoic autochthonous unit of Lesser Himalayan Metasedimentary sequence and is exposed around north of Chakrata to south of Tiuni in Tons valley. The lithological-structural mapping on 1:25,000 scale has been carried out in part of Tons valley and its tributaries in Kumaun Lesser Himalaya. Deoban Group comprises Dharagad, Bajmara and Sauli formations. These rock units represent the near shore deposition environment to shallow marine shelf and stable tidal flat conditions. The arenaceous facies dominates over argillaceous of Dharagad Formation and disconformably grades into carbonate dominated argillaceous facies of Bajmara and Sauli Formations. Study of sequential development of structures indicates F1 to F3 folding including thrusting episode. The first two deformations bear the signatures of co-axial deformation followed by change in stress field that indicates non-coaxial deformation event. The mineralization in the Tons valley indicates the presence of polymetallic sulphide mineralization in the form of chalcopyrite, galena, sphelerite, pyrite and altered products malachite, azurite and bornite that took place during second phase of deformation. Their occurrences are restricted with shear, fractures and tension gashes indicate the epigenetic and structural control of mineralization. The geochemical analysis carried out in altered carbonate and quartzite indicates the presence of Pb 1.5% and Zn upto 1.2 % at Pheiya Khera – Hartar area.
Keywords: Structural Evolution, Sulphide Mineralization, Deoban Group, Tons Valley, Lesser Himalaya
