Komatiite-hosted Ni-Cu-(PGE) deposits - newgenco pty...
Transcript of Komatiite-hosted Ni-Cu-(PGE) deposits - newgenco pty...
Komatiite-hosted Ni-Cu-(PGE) deposits: understanding deposit and camp footprints
Steve BeresfordSteve Beresfordnewgenconewgenco
AcknowledgementsAcknowledgements�� CoCo--authorsauthors
•• Marco Marco FiorentiniFiorentini•• Jon Jon HronskyHronsky•• Nic Nic RosengrenRosengren•• Dave Dave BertuchBertuch•• Paul Paul DuuringDuuring•• Ahmad Ahmad SaleemSaleem•• Bill StoneBill Stone•• Mark Mark BarleyBarley•• Mark Mark BarleyBarley•• Ray CasRay Cas•• Ben Ben GrguricGrguric
�� Former colleagues Former colleagues at WMC and at WMC and BHPBillitonBHPBilliton�� Various company support over last 10 years, Various company support over last 10 years,
WMC, Falconbridge, INCO, WMC, Falconbridge, INCO, LionoreLionore, MPI, MPI�� Collaborators and Sponsors of AMIRA P710Collaborators and Sponsors of AMIRA P710�� Host of past students and Host of past students and postdocspostdocs
TALK OutlineTALK Outline�� IntroductionIntroduction
�� Focus on new ideas on geological, Focus on new ideas on geological, geochemical and geophysical geochemical and geophysical footprintsfootprints
1. Continuum of deposit styles and 1. Continuum of deposit styles and controlscontrols
2. Deposit diversity 2. Deposit diversity Footprint of these diverse stylesFootprint of these diverse styles
How our exploration methodologies changeHow our exploration methodologies change
3. Camps3. CampsNeed to improve predictive methodologiesNeed to improve predictive methodologies
Take home messagesTake home messages�� KomatiiteKomatiite hosted Nihosted Ni--CuCu--(PGE) deposits exhibit (PGE) deposits exhibit considerable diversity (in terms of massive considerable diversity (in terms of massive sulfidesulfidetypes)types)
�� Kambalda is only an end memberKambalda is only an end member
�� Significant variation in Significant variation in exploration strategy exploration strategy between between the deposit end membersthe deposit end membersthe deposit end membersthe deposit end members
�� Despite 40 years of exploration they are still truth Despite 40 years of exploration they are still truth machine intensive machine intensive –– we must maximise in hole data?we must maximise in hole data?
�� Do isolated Do isolated komatiitekomatiite--hosted Nihosted Ni--CuCu--(PGE) deposits (PGE) deposits represent underexplored camps? represent underexplored camps?
�� We outline current knowledge in delineation of camps We outline current knowledge in delineation of camps but further work is required at a scale rarely attempted.but further work is required at a scale rarely attempted.
Our Our common view of common view of komatiitekomatiite--hosted Nickel hosted Nickel sulfidessulfides
is is Kambalda Kambalda centriccentric
Frost 1992
30+ years of outstanding discovery and production of the same style
Cowden 1986
Primary sulfide texturesPrimary sulfide textures
Katinniq
Blebby ore
Yakabindie
Foster
Secondary Secondary sulfidessulfides texturestextures
The search for footprints to Ni-Cu-(PGE) deposits
Kelley2 2007
The best and possibly the only reliable geochemical tracer of komatiite associated
nickel sulfide deposits is the presence of Ni sulfides” Barnes et al 2004
PROXIMAL
DISTAL
1. Continuum of deposits1. Continuum of deposits
�� Controls on diversityControls on diversity
•• Parent magmaParent magma
•• Emplacement (intrusive vs extrusive)Emplacement (intrusive vs extrusive)
•• Host rockHost rock
�� Parent magma variation (part of Parent magma variation (part of continuum for all NiS)continuum for all NiS)
-- Genetic and exploration significanceGenetic and exploration significance
-- Recognition and implications of Recognition and implications of komatiitic basalt Raglan style deposits in komatiitic basalt Raglan style deposits in the Yilgarn eg Collurabbie, Windarrathe Yilgarn eg Collurabbie, Windarra
1. Parent magma Continuum1. Parent magma Continuum15
25
20
Windarra
Fortaleza
Shebandawan
Raglan*
Thompson*
Collurabbie
1300 C - 2 PaSO
MgO
30
35
Komatiite Transitional Komatiitic basalt
Perseverance
Mt Keith
Kambalda
1600 C - 0.01 PaSO
MgO
* Proterozoic
Archaean komatiitic basalt depositsArchaean komatiitic basalt deposits
Geochemistry
• Cr saturation (Ni:Cr vectors are
not applicable)
• High PGE, Pd:Ir
• MgO contents (lower Fo)
Geology• Oikocrystic peridotites and pyroxenites
• Poddy ore bodies• Poddy ore bodies
• Thick internal sulfides
• Thick matrix sulfides possible (50-60m)
• Diversity of new sulfide textures including Leopard
texture sulfides
Geophysics
• Discontinuous conductors (line spacing, moving loop)
• Constrain geometry (magnetic inversion)
2. Deposit diversity and footprint2. Deposit diversity and footprint
�� Numerous classification schemesNumerous classification schemes�� Main textural association of sulfidesMain textural association of sulfides
•• Type 1Type 1•• Type 2Type 2•• Type 3Type 3•• RemobilisationRemobilisation
�� GeneticGenetic
3Boston Creek
Wiluna
Mt Clifford
�� GeneticGenetic•• Intrusive vs extrusiveIntrusive vs extrusive
�� CompositionalCompositional•• Dunite vs PeridotiteDunite vs Peridotite
�� Biggest control is host rockBiggest control is host rock-- facies associationfacies association•• Komatiite basaltKomatiite basalt•• Komatiite felsicKomatiite felsic•• KomatiiteKomatiite--sedimentsediment
1 2Kambalda
Perseverance Mt Goode-Cosmos
Goliath
Six Mile
Mt Keith
A. A. KambaldaKambalda style depositsstyle deposits�� Seminal work of Woodall, Ross, Seminal work of Woodall, Ross,
Gresham et al has stood the test of timeGresham et al has stood the test of time�� Well understood derivative exploration Well understood derivative exploration
modelmodel
Recent ideas:Recent ideas:�� Channel and trough are not the sameChannel and trough are not the same�� Increasing use of structure and 3D Increasing use of structure and 3D
tenor variation as exploration tooltenor variation as exploration tooltenor variation as exploration tooltenor variation as exploration tool�� Ni dispersion into footwallNi dispersion into footwall�� Diversity of sediment association and Diversity of sediment association and
thickness variationsthickness variations�� StratigraphicStratigraphic correlation of sedimentary correlation of sedimentary
units with units with felsicfelsic volcanicsvolcanics (below) (below) �� Camp Spacing is predictable within Camp Spacing is predictable within
campscamps
Distal felsic fall deposit intercalated with Silver Lake Peridotite, Kambalda
Exploration Exploration
�� Basal flow thickness Basal flow thickness (>30m)(>30m)
�� SedimentSediment--ore ore antithetismantithetism�� High High MgOMgO thick cumulates, thick cumulates,
High Ni, High Ni, Ni:CrNi:Cr�� Amygdaloidal domains are Amygdaloidal domains are
commoncommoncommoncommon�� Sediment free ore prismSediment free ore prism�� Ore environment is Ore environment is
structurally complex with structurally complex with prominent prominent metasomaticmetasomaticzones and chlorite zones and chlorite tectonitestectonites (originally (originally termed chlorite sediments)termed chlorite sediments)
Seat 2002
TroughTrough--Channel CrossChannel Cross--Cutting Cutting Relationships at KambaldaRelationships at Kambalda
N
trough
channel
Lunnon Fisher
N
Stone et al 2006
trough
channel kilometres
0 0.5
Ken
Ken
volcanic
Lower
channel
Trough
kilometres
0 0.5
McMahon
Ken-McMahon
McMahon channel (no trough)
McMahon
thrust
FWB
KLT
k ilomet res
E
Ni leakage and dispersionNi leakage and dispersion
Lunnon shoot
Anomalous Ni in basalts (>600 Anomalous Ni in basalts (>600 ppmppm) beneath the ) beneath the ore shootore shoot
Stone et al 2006