Geology, mIneralisation and Genesis of the Alkaline Dinkidi Cu-Au Porphyry, North Luzon, Philippines

摘要

The Dinkidi Cu-Au porpphyry deposit is situated in the Caraballo Range of North Luzon, Philippines, Although comparatively small, Dinkidi has unusually high gold grades with drilling by Climax-Arimco Mining Corporation delineating a 110 Mt orebody at 1.2 g/t gold and .5 per cent copper. The magmeatic-hydrothermal evolution of Dinkidid records a distinctive switch in mineralisation from an early orthoclase-dominated Au-rich assemblage, typical of alkaline porphyry systems, to a later quartz stockwork Au-Cu rich assemblage typcial of most calc-alkaline to shoshonitic porphyry systems. The early orthoclase-dominated stage is associated with the intrusion and crystallisation of a variably-textured clinopyroxene-syenite dyke that contains high-grade (5-20 g/t) gold mineralisation. We consider this dyke to be a Cu-Au porphyry analogue to the pegmatites found in granitic systems.