EGS-relevant review of metallogenesis

This deliverable is related to Task 1.1, which will result in a synthesis of our understanding of the types of metallic mineral occurrences that exists at depths below existing levels of conventional mining. We are aiming to investigate mineral potential in depth and temperature zones that are currently the target of EGS (depth of 4 km or more and ambient rock temperature in excess of 180 °C). The geometry, extent, structure and textural characteristics of mineralisation are primarily influenced by the host rocks, magmatic/hydrothermal processes and fluid-rock interaction. Understanding the origin, genesis and scale of fracture systems (mineralisation frequently develops in fractures) is also vital. All EGS projects as well as hydrothermal systems all over the world show that natural fractures play an important role in controlling deep fluid circulation and heat extraction from deep ground layers. Understanding the genesis of natural fracture pattern hence is also vital for the effective development of geothermal projects in general and EGS in particular. The focus of the review will concern deposit genesis, composition, (sub)types, etc. International analogues will also be reviewed (e.g. South African gold deposits, Canadian Cu-Ni volcanogenic massive sulphides, Australian porphyry copper-gold deposits). Previous work using deep penetration high resolution geophysical methods on ultra-deep ore deposits will be re-evaluated to determine key geophysical exploration criteria for deep seated ore mineralization.