Accessory minerals as fertility indicators in copper porphyry systems

Porphyry copper deposits host three quarters of the worlds copper resources. Despite generally greater agreement on the processes leading to mineralization, it is still debated what makes a magmatic system 'fertile', possessing the ability to form large resources.

Due to the hydrous nature of porphyry mineralization, whole rock geochemistry is often distorted and potentially misleading. Analysing robust accessory minerals e.g. zircon grants the unique opportunity to see through alteration and investigate the previously active magmatic conditions during petrogenesis. My project aims to compare the geochemistry of several accessory minerals within 'fertile' and 'barren' magmas (no potential for mineralisation). This will involve the study of pre-, syn- and post-mineralization rocks from the world class Santo Thomas II Cu-Au deposit, Luzon, Philippines. These geochemical signatures will be compared with those found in modern analogues of 'fertile' (Pinatubo) and 'barren' (Taal) systems. This will allow the investigation of key magmatic processes leading to the, still ambiguous, generation of porphyry copper fertility.

This project will also investigate the role of magmatic brine lenses believed to be forming at Tall.