Geology, Rock Geochemistry and Ore Fluid Characteristics of the Brambang Copper-Gold Porphyry Prospect, Lombok Island, Indonesia.

Brambang is one of the porphyry copper-gold prospects/deposits situated along eastern Sunda arc. This study aimed to understand geological framework, alteration geochemistry and ore fluid characteristics prospect. Fieldworks various laboratory analyses were performed including petrography, microscopy, rock geochemistry, chlorite chemistry inclusion microthermometry. The prospect composed andesitic tuff diorite which are intruded by tonalite porphyries. Tonalite porphyries interpreted as mineralisation-bearing intrusion. Various hydrothermal alterations identified potassic, phyllic, propylitic, advanced argillic types. Ore mineralisation characterized magnetite copper sulfides such bornite chalcopyrite. Potassic typified secondary biotite, associated with mineralisation. Mass balance calculation indicates SiO2, Fe2O3, K2O, Cu Au added during potassic process. forming dominated magmatic at high temperature (450-600ºC) salinity (60-70 wt. % NaCl eq.). Hydrothermal was diluted meteoric water incursion low-moderate 150-400ºC 0.5-7 eq.