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GeoDiscovery members have extensive
global experience in a wide range of base and precious
metal commodities. This includes:
Magmatic sulphide
deposits are significant economic producers of Ni,
Cu, Co and the platinum group elements (PGE). The
deposits are found throughout geological time and
are associated with a diverse range of magma types.
Significant accumulations of magmatic sulphides are
generally found in association with komatiitic to
komatiitic basalt lava flows, deeper-level subvolcanic
conduits and magma chambers. World-class examples
include the Bushveld Complex (RSA), Thompson (Canada),
Sudbury (Canada), Jinchuan (China), Voisey's Bay (Canada)
and Noril'sk - Talnakh (Russia).
Magmatic sulphide systems
represent a spectrum of deposits that are economically
significant to both major and junior mining houses,
characterised by high value ore with potential for
world-class resources. GD members have significant
global exploration experience for magmatic sulphide
systems. Exploration strategies are based on the integration
of geological, geochemical and geophysical responses,
coupled with a detailed understanding of the geodynamics
of magmatic sulphide bearing provinces. Back
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Intrusion-related Cu-Au and Au systems form
a spectrum of economically significant deposits that
range from classic porphyry Cu-Au deposits to the
more recently recognised and described Au-only systems
(e.g. Fort Knox, Pogo, Donlin Creek). The style and
geochemistry of individual systems (and districts)
can be related to a complex interplay between emplacement
depth, magma chemistry, host rock composition, structural
setting and the influence of exotic fluids. Understanding
this interplay and applying the concepts to all scales
of exploration from regional generative projects,
to detailed prospect evaluation can greatly enhance
the effectiveness of projects.
GD members have extensive
experience in the exploration for the full range of
intrusion-related systems, from province-wide generative
studies through to in mine resource definition. Exploration
strategies built around defining the geological, geochemical
and geophysical products of these diverse systems
offer the greatest probability of success. Back
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Epithermal Au deposits are economically
attractive exploration targets for both major Au-focussed
mining houses and junior companies due to their wide
range of grade-tonnage scenarios. Definition and understanding
of epithermal systems is complicated by confusing
classification schemes and associated terminology
that can result in ineffective exploration strategies.
GD members have significant
experience in exploration and mining of epithermal
Au deposits and take a pragmatic approach based on
defining the key alteration products of a system and
applying appropriate geological, geochemical and geophysical
methods. Back
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Broken Hill-type
(BHT) deposits are a poorly understood and often-controversial
category of sediment hosted metamorphosed massive
sulphides. Known deposits occur in Paleo-Mesoproterozoic
amphibolite to granulite facies metamorphic belts.
Due to complex metamorphic, metasomatic and structural
overprints it is difficult to define pre-metamorphic
relationships with any certainty. As a consequence
exploration strategies biased too heavily towards
pre-metamorphic genetic models are often ineffective.
Despite these difficulties,
the high-grade and excellent metallurgical performance
of BHT deposits makes them attractive and often under-explored
targets. Through direct involvement in the discovery
by BHP of the world-class Cannington BHT Ag-Pb-Zn
deposit in the Mount Isa Inlier, GD members have extensive
experience in the successful application of exploration
strategies and property assessment to BHT districts
and deposits. Strategies are based on a pragmatic
approach involving definition and ranking of key associations
and their expression in regional and prospect scale
datasets. Back
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Iron oxide associated Cu-Au
(IOCG) systems are an economically significant deposit style
that has become an important target type in the portfolio
of many companies. Deposits with IOCG affinities occur in
a variety of geological settings around the world particularly,
with a significant endowment peak in Paleo-Mesoproterozoic
terrains. Examples of world-class deposits in the Proterozoic
are known from Australia and Brazil, with ongoing exploration
programs in Scandinavia, central Africa, India and Canada.
Mesozoic to Cenozoic-aged IOCG examples occur in Chile and
Peru.
Typical IOCG districts are associated
with regional scale magnetite-hematite bearing alteration
systems, with economic mineralisation confined to specific
(generally late stage) paragenetic events. Understanding
the complex multi-phase nature of IOCG alteration systems
with effective exploration strategies based on integrated
geophysical, structural and lithogeochemical techniques
are critical aspects. GD members have extensive experience
and demonstrated success in developing exploration strategies
for IOCG mineralization styles particularly in Proterozoic
terrains. Back
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Sedex deposits represent
some of the world's largest accumulations of Zn, Pb and
Ag. Stratiform and stratabound mineralisation is associated
with reduced host sequences in a variety of clastic sedimentary
basin settings, with endowment peaks in the Mesoproterozoic
and late Paleozoic. These settings include intracratonic
rift basins (e.g. Mount Isa, Sullivan) and passive margins
(e.g. Selwyn Basin). Recognition of this diversity and an
understanding of basin evolution histories are important
for developing effective Sedex exploration strategies.
GD members have extensive global
experience in regional terrane/basin evaluation and target
definition for Sedex basins. This also involves direct involvement
in exploration programs throughout the world-class Carpentaria
Zn Province in Northern Australia (e.g. Mount Isa, Century
and McArthur River). Back
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The primary sources of
economic concentrations of diamond are volcanic diatremes
formed from kimbelitic and lamproitic magmas. In geological
terms the majority of economic kimberlites are relatively
young (Mesozoic), however they are dominantly found in close
association with variably covered Archaean aged cratonic
nuclei. Diamonds are formed at depths of ~ 180 km within
the earth's mantle and have a close association with eclogitic
and peridotitic (to harzburgitic) nodules leading to the
terms P and E-type diamonds. These nodules and associated
transporting magmas yield a suite of diagnostic indicator
minerals whose chemistry can be used to identify the presence
or absence of potentially economically significant kimberlites
and lamproites.
GD members have extensive experience
of diamond exploration in a variety of climatic environments
ranging from arctic to tropical. Moreover, key members have
a detailed understanding of the complex chemistry of indicator
minerals and the highly variable geophysical and geochemical
responses that are associated with both kimberlites and
lamproites.
Back to the Top
The genesis of the sediment-hosted
Au systems (eg Carlin, Nevada; Sepon, Laos) remains controversial
despite world-class Au production. The deposits involve
a complex interplay between stratigraphy, structure, diagenesis
and magmatism. The deposits are often characterised by subtle
surface expression and care is needed in all stages of exploration
from target generation to prospect evaluation. Exploration
for sediment-hosted Au borrows much of its approach from
the sediment-hosted base metal field with understanding
basin-evolution a key factor.
GD members have experience in
using basin evolution techniques to effectively explore
for sediment-hosted Au systems. Back
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Archean Lode Au deposits
represent a wide variety of structurally-controlled styles
hosted in stable granite-greenstone terrains predominantly
of Archean-Paleoproterozoic age. Much of the world's gold
production is from small to medium-sized deposits that are
economically attractive to junior mining companies. This
is a function of the potentially high-grade nature of mineralisation
with well defined 'lodes' and the ability to process ores
using low-cost technologies. The attractiveness of the deposit
style is further enhanced by deep lateritic weathering resulting
in supergene enrichment and friable ores that can be easily
mined and treated with CIP or CIL technologies.
Lode Au mineralisation occurs
in virtually all global granite greenstone terrains. Significant
examples include the Western Australian Yilgarn Craton,
the Canadian Superior Province, the Zimbabwean Craton, the
Amazonian Craton, and the west African Birimian belts. GD
members have significant experience of exploration in Lode
Au terrains from greenfields exploration through to deposit
evaluation. Back
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VHMS deposits are an important
economic source of Cu and Zn often associated with significant
Ag, Au, Cd, Bi or Sn credits. The multi-commodity and high
value nature of mineralisation makes them an attractive
exploration target for both major and junior mining companies.
VHMS deposits occur in greenstone belt, island arc and back-arc
settings that range in age from Archean to recent. A characteristic
feature is district scale clustering with numerous low-tonnage
uneconomic occurrences and a small number of giants (e.g.
Kidd Creek, Bathurst No. 12).
The relatively small size and
proliferation of sub-economic occurrences presents a significant
challenge. Effective exploration strategies involve a detailed
understanding of favorable lithostratigraphic settings and
marker horizons; relationships to structural controls and
volcanic architecture; and the use of lithogeochemistry
in recognition of alteration systems and vectoring. Use
of integrated high-resolution geophysical techniques is
also an important aspect given the high Fe sulphide content
of typical VHMS systems. GD members have been involved in
district and prospect scale exploration programs for VHMS
deposits. This includes particular expertise in exploration
for metamorphosed VHMS mineralisation and use of specialized
geophysical techniques integrated with 3D visualisation.
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MVT deposits are a varied
family of epigenetic Pb-Zn mineralization styles hosted
predominantly by dolostone sequences of Paleozoic-Mesozoic
age. Undeformed orogenic foreland carbonate platforms are
the favored tectonic settings. MVT districts can cover extensive
areas and although individual deposits and ore shoots are
often limited, aggregate tonnages represent significant
Pb-Zn resources that produce 'clean' concentrates. District
scale controls are varied and include shale pinch-outs,
limestone-dolomite transitions, solution collapse breccias,
reef complexes, faults and basement topography.
MVT mineralisation can represent
challenging exploration targets. Primary geochemical halos
are restricted in size and use of electrical geophysics
is often limited to detection of Fe sulphide halos using
IP. Grid drilling based on geostatistical parameters is
an effective exploration strategy. GD members have been
directly involved in regional exploration programs and deposit
scale studies for MVT deposits. Back
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