Structural and geochemical characteristics of the Ngunala Intrusion of the Giles Complex, Musgrave Province, South Australia

Abstract

The Ngunala Intrusion is a poorly understood layered mafic-ultramafic intrusion that forms part of the voluminous Giles Complex intrusions (∼1080 Ma) of the Musgrave Province. Preliminary geochemistry, petrology and field observations indicate that the Ngunala Intrusion is composed of a series of discrete magmatic pulses. The identification of rare fragments of pentlandite and chalcopyrite in the southern outcrop of the Ngunala Intrusion indicates that the host magmas reached sulphur saturation and highlights its potential to host magmatic sulphide mineralisation. The Ngunala Intrusion is located in close proximity to a major crustal scale structure proposed to have acted as a major magma conduit. The series of discrete magmatic pulses identified in outcrop and interpreted at depth, describes an active, dynamic magmatic environment to allow for magma mixing. The Ngunala Intrusion is host to several characteristics that describe the appropriate physical environment required to concentrate the sulphides into a deposit.