CRITICAL METAL DISTRIBUTIONS WITHIN THE VOLPA SMS DEPOSIT: A COMPARATIVE MODEL FOR MAGMATIC VOLATILE FLUX?

The VOLPA seafloor massive sulphide deposit is a previously uncharacterized vent field located on the Niua Volcanic Complex, which is the northernmost volcanic edifice of the Tofua volcanic Arc, SW Pacific. The VOLPA deposit is characterized by trachyandesitic host rocks of variable permeability, which affects seawater infiltration rates, thereby manifesting in contrasting temperature profiles of hydrothermal fluids between the eastern and western vent fields. The VOLPA deposit represents a unique comparative model for exploring the effects of magmatic volatile influx on the geochemistry and petrology of SMS hydrothermal precipitates, as VOLPA is adjacent to two other SMS deposits on the same volcanic complex: Niua South (confirmed lack of magmatic volatile flux), and Niua North (confirmed magmatic volatile contributions). In conjunction with previously acquired bulk geochemistry, EPMA, SEM, and LA-ICP-MS data, newly acquired in-situ sulfur isotope data helps to elucidate the effects of magmatic volatile flux on both the geochemistry and mineralogy of the VOLPA deposit. By comparing the geochemistry of the VOLPA deposit to the adjacent deposits (Niua North and Niua South), the effects of magmatic volatile overprinting are further elucidated, providing greater insights into the evolution of arc-hosted SMS deposits, both in modern and ancient settings.