Trace elemental systematics of auriferous sulfides within the dolerites of northern Cuddapah Basin, southern India: Implications for invisible gold mineralization

Abstract

In the present work, the trace elemental systematics of the dolerite-hosted auriferous sulfides have been carried out to understand the nature of invisible gold mineralization within the northern part of Cuddapah Basin, southern India. The whole-rock geochemistry suggests that the dolerite is derived from a spinel peridotite mantle source and emplaced as a result of the intraplate magmatic activities. Within the dolerite, pyrite is the dominant phase associated with chalcopyrite and magnetite. Two types of pyrite phases are identified on the basis of their textures, i.e. Py1 and Py2. Py1 is anhedral to subhedral, whereas Py2 is euhedral. The Co/Ni ratio of Py1 and Py2 suggest their hydrothermal and volcanic origin, respectively. The gold vs arsenic plot indicates that gold occurs as solid solution within pyrite. Py1 is comparatively enriched in gold than Py2. Along with gold, other trace elements like As, Se, Ga, Ge, Sb, Te, and Ti are also present within these pyrite phases. The positive correlation of the gold with these trace elements indicates its solid solution nature. Py2 has a lesser content of gold than Py1, because of the higher ambient temperature. This work is the first report on the invisible gold occurrences within the dolerite hosted sulfides and provides new insights into the gold metallogeny of the northern Cuddapah Basin. The findings also contribute to the broader understanding of the trace elemental behavior in ore-forming processes, particularly in the context of invisible gold within sulfide minerals, which may have exploration implications in this region.