Voisey’s Bay Type DepositsThe Giles Complex displays several...

Voisey’s Bay Type Deposits
The Giles Complex displays several characteristics that highlight its potential for magmatic Ni-Cu deposits.

The Giles Complex (~1080 Ma) is an extensive voluminous mafic-ultramafic intrusive sequence that is scattered over an area of some 2500km2
The layered mafic-ultramafic bodies experienced a multiple-phase history
The E-W trending Mann-Hinckley Fault and pre-existing N to N-NE trending deep basement structures are crustal scale fractures that were active around the time of the emplacement of the Giles Complex (1080 Ma) and could potentially have been the corridor that allowed for the emplacement of a Ni-Cu bearing upper mantle melt component the Giles Complex
The interaction of later stage olivine-dolerite dykes/sills with earlier peridotites, gabbros and troctolites has the potential to form Voisey Bay style Ni-Cu mineralisation
The Giles Complex also exhibits a series of vertically stacked magma chambers and associated feeder dykes that could potentially act as traps for the immiscible Ni-Cu sulphides
The emplacement of the melts coincided with an extensional period during granulite facies metamorphism
Massive and disseminated nickel and copper sulphides intersected during recent work by WMC on the WA side of the Musgrave Province (Nebo and Babel) are believed to be associated with the later stage dolerite dykes of the Giles Complex intrusions indicating that Ni-Cu mineralisation processes where occurring during the emplacement of the Giles Complex.


Broken Hill Type Deposits
The Proterozoic metasedimentary components within the granulite grade gneisses of the Birksgate Complex could potentially host a Broken Hill Type (BHT) deposit.



The stratigraphy of the units within the Birksgate Complex are poorly defined which prevents any detailed stratigraphic correlations, however several geological features have been identified within the Birksgate Complex that could be indicative of a BHT deposit.

On the Eateringinna 100K mapsheet, geochemically interesting assemblages including zinc-bearing spinels (gahnite), manganese garnet, garnetiferous sandstones (Coticules), calcsilicates, ferruginous quartzites and iron formations could potentially represent a hydrothermal fluid alteration system similar to BHT.
Some occurrences of pyrite has been identified in the Birksgate Complex
The Birksgate Complex was emplaced around the mid Proterozoic, however the crustal architecture at this time is poorly understood and requires further research
Evidence for a multiple deformation history during the Proterozoic has been identified at ca 1200-1170 Ma associated with the Musgravian Orogeny and ca. 550 Ma with the Petermann Orogeny. With debatable evidence for earlier metamorphic events around 1400 and 1300 Ma.