Auriferous volcanogenic massive sulfides in Paleoproterozoic volcano-sedimentary sequence of Aravalli Fold Belt in Dugocha Area, Udaipur District, Rajasthan, NW India

The Proterozoic rocks of the Aravalli and Delhi Fold Belts are known to host several massive sulfide deposits of economic importance. Author report here, auriferous massive sulfide mineralisation from Palaeoproterozoic carbonate dominated volcano-sedimentary sequence at Dugocha, NW India. Gold occurs in the association of Fe-As-Cu-Ni sulfides hosted in metavolcanic rock and dolomite. Tuffaceous exhalite is spatially associated with metavolcanic rock hosting Cu-Au bearing sulfide deposit in the study area. In metavolcanic, tourmaline occurs as disseminations. In tuffaceous exhalite, tourmaline occurs as in the form of > 15% tourmaline-rich layers and as zoned tourmaline as discrete grains. Analytical data of tourmalines compares well with the composition of dravite. These Mg-rich tourmalines show a low Fe/Al ratio. Low Fe/Al ratio suggestive of exhalative origin and Mg-rich tourmaline are characteristics of massive sulfide deposits. The fluid inclusion data suggest high salinity aqueous phase and homogenisation temperature of similar to 150 degrees C associated with sulfide deposition. The well-constrained delta S-34 values of +10.17 and +12.08 permil with an average of +11.2 permil compare well with those of fluids of Discovery Deep median trench of the Red Sea. The high isotopic composition is suggestive of mixing of reduced seawater with stripped-out sulfur from the magma chamber by hydrothermal fluids. These auriferous sulfides charged with high salinity aqueous phases were deposited in a volcanic environment. The mineralisation associated with metavolcanic in Dugocha formed during the first stage of the Aravalli rift at similar to 2 Ga is associated with volcanism and hydrothermal activity through the circulation of hot brines charged with high salinity.

Automated summary

This study reports the presence of gold-bearing sulfides in a Palaeoproterozoic carbonate-dominated volcanic-sedimentary sequence in the Dugocha area of northwest India. These auriferous sulfides charged with high salinity aqueous phases were deposited in a volcanic environment.