Mineral Systems
in Mineral Potential Evaluation
Ferenc Molnár
STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI
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Subjects of Presentation
•Mineral system approach, mineral system models
•The MINSYSPRO project and consortium
•Orogenic gold mineral systems
- methods of research
- examples for determination of critical processes
and parameters; Hattu Schist belt, Peräpohja Belt,
Central Lapland Greenstone Belt
•Links to mineral prospectivity mapping
STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI
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Gold
Mineral Systems, Models and
Mineral Potential Evaluation
Mineral Systems
- all geological factors that control origin and preservation of mineral deposits
approach
Mineral System Model
- definition of
sources
transportation
accumulation
re-mobilisation
ore components
modeling
mappable parameters
Mineral potential evaluation
-incorporation of mappable parameters of mineral system models
into mineral prospectivity evaluations
STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI
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prospecting
Mineral Systems: Critical Processes and Parameters
Primary and secondary
dispersion
Accumulation processes
Vectors to ore
Structures
Geodynamic processes – Source rocks
STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI
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Processes in Mineral Systems and Mappable Criteria
Critical
processes
Critical
parameters
Geological
features
Mappable
Primary
mobilization
Transportation
Change in physical state
of fluids
Alteration mineralogy
Geophysical response
Deposition
Preservation/Re-mobilization
Change in chemical state
of fluids
Rocks with favourable chemistry
Lithogeochemistry
Characteristics
of fluid/rock interaction
Chemical gradients
in composition of rocks
Remote sensing response
criteria
Modified after McCuaig et al., 2010
Link between mineral system research
3D modeling and mineral prospectivity mapping
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STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI
Mineral Systems and Mineral Prospectivity in Finnish Lapland
MINSYSPRO
Academy of Finland supported project on primary mineral resources
Consortium:
Geological Survey of Finland
University of Oulu
Experts from foreign universities
UK, Sweden, France, Norway
From 09.2014, four years
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Ore geology seminar 02.02.2015
What was the idea behind the project?
-Mineral system approach
-Critical processes and footprints (vectoring) in orogenic gold and magmatic
mineral systems
-Conversion of critical processes into mappable criterias
-Incorporation of parameters of critical processes and mappable criterias
into 2D-3D geological models
-Forward modeling
-Transferring of the new knowledge and mappable criterias to conceptual
and empirical mineral prospectivity mapping
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Ore geology seminar 02.02.2015
Workflow of the Project
New targets for
mineral exploratiom
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Ore geology seminar 02.02.2015
Research on Orogenic Gold Mineral Systems:
Outstanding Questions - Examples
Central Lapland
Greenstone Belt
Sources of ore forming fluids and components
-magmatic, metamorphic, other?
Peräpohja Belt
Kuusamo Belt
Hattu Schist Belt
Footprints of gold enrichments
- which parameters are applicable for vectoring towards ore?
Multiple mineralization events
- different stages in one system or superimposition of
independent systems?
Effect of superimposing events on composition
and quality of ore
- dispersion or concentration?
STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI
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Repetition of processes at all scales
OVERPRINT
ORE
REMOBILIZATION
10-100s km
Studies of minerals at the micro scale
can be used to decipher processes at
the km+ scale
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100s µm
BSE image, sulfides (bright) in primary silicates
(med grey) with alteration (dk gray)
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Cutting Edge Analytical Tools Applied in Mineral System Research at GTK
JEOL JSM 7100F
high resolution
FE-SEM
Mineralogy
Nu Plasma MC-ICP-MS
with laser microprobe
Nu AttoM HR-ICP-MS
with laser microprobe
Geochronology, stable and radiogenic isotopes, trace elements
Linkam MDSG 600 microT
In situ high analyses with high spatial resolution
Simple sample preparation – mostly polished thin sections
Fluid inclusions
Multiple isotope/trace element/fluid inclusion analyses
from the same sample and even from the same mineral
grain.
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Source of Fluids
Boron Isotopes in Tourmaline , Hattu Schist Belt, Eastern Finland
Metasedimentary
Tourmaline veining in intrusive rocks
Massive tourmalinization in
metasedimentary units
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Magmatic
Copper and sulphur isotope analyses
in chalcopyrite by LA MC ICPMS
Source of Fluids:
Potential Use of Unconventional Stable Isotopes
Hattu Schist Belt, Eastern Finland
Further research on
-Proterozoic orogenic gold systems
- Fe, Zn and Mo isotopes
Magmatic fluids
Fluids from the
metasediments
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Fluid Sources – Mappable Criterias
207Pb-206Pb
Zircon
ages :
No
ORE
ORE
Zircon 207Pb-206Pb
age
2712±4 –2717±8 Ma
2725 ± 12 Ma
Feldspar porphyry
Strong alteration and
disseminated ore
Mappable criteria?
-
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Tonalite
weak alteration
Geophysical response?
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Mappable Criterias – Geophysical Response
Petrophysical Properties of Mineralized Source Rocks and Barren Intrusions
Pampalo Mine, Hattu schist Belt
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Lead isotopes: galena, hydrothermal K-feldspar
Late Svecofennian (1.81 Ga) K-metasomatism
Effect of Remobilisation on the Quality of Ore
Pampalo Mine, Hattu schist belt
Late Svecofennian (1.81 Ga) thermal event
Ar-Ar thermochronology
K-feldspar deposition
High grade ore in K-feldspar-bearing
alteration zones
Mappable K-anomalies
Molar element ratios in the host rocks compared tomolar element ratios of alteration mineralsss
STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI
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Traps for Formation of High Grade Gold Concentration
Rompas, Peräpohja Schist Belt
Uranogenic lead in Pb-minerals
Trap 2: pyrobitumen nodules
Gold
Trap 1: uraninite grains
(U,Pb*)O2
2Au(HS)2ˉ + H2 + Pb*2+
2Au(HS)2ˉ+ 2H2 + Pb*2+
[Au2Te4]4- + 2H2 + 4Pb*2+
UO2 + Pb*2+
2Au + Pb*S + 3H2S
Au2Pb* + 4H2S
2Au + 4Pb*Te + 4H+
Scavenging of sulphur from gold
transporting fluids
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Po
Aspy
Geochronology of multiple hydrothermal events:
Kuotko, Central Lapland Greenstone Belt
Au
Hydrothermal xenotime from carbonate veins:
U-Pb geochronology by LA MC ICPMS
Bi
Early arsenopyrite bearing mineralization
superimposed by native bismuth-gold-pyrrhotite
in veins with multiple carbonate deposition
1739 Ma
1814 Ma
1778 Ma
1808 Ma
1822 Ma
Intercept at 1769 ± 9 Ma
MSWD = 0.49
Probablity of fit 0.97
Intercept at 1854 ± 14 Ma
MSWD = 0.28
Probablity of fit 0.96
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Summary
Critical processes of ore
formation and preservation manifested by
mappable geological and
geophysical features
Mineral system
research
2D-3D-4D modelling
Spatial and temporal distribution of geological
features that record
critical processes
STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI
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Conceptual and empirical
evaluation of mineral
potential and selection of
areas for exploration
Mineral prospectivity
mapping
Research teams:
orogenic gold mineral systems and mineral prospectivity mapping
Research on critical processes and key parameters
of orogenic gold mineral systems; workgroup 1
Models and mineral prospectivity
mapping, workgroup 3
Ferenc Molnár
Hugh O`Brien
Peter Sorjonen-Ward
Sayeb Muhammad
Antonin Richard (France)
Ian Pitcairn (Sweden)
Harry Oduro (U.K.)
Holly Stein (USA/Norway)
Vesa Nykänen
Satu Mertanen
Tero Niiranen
Eeva-Lisa Laine
Ilkka Lahti
Jouni Lerssi
Ilkka Suppala
Postdoctoral researcher
from 01.01.2015
Alexander Middleton
Postdoctoral researcher
from 01.09.2016 to 30.08.2018
T.B.N.
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Ore geology seminar 02.02.2015
Research teams: magmatic mineral systems
Univeristy of Oulu:
Eero Hanski
Shenghong Yang
Markku Pirttijärvi
Wolfgang Maier, (U.K.)
GTK:
Hannu Huhma
Yann Lahaye
Tuomo Karinen
Jukka Konnunaho
Tuomo Törmanen
Two Master’s students (2x3 months)
Doctoral student
from 01.09.2014 to 30.08.2018
Marko Moilanen
First Quantum Oy.:
Petri Peltonen
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Ore geology seminar 02.02.2015
Orogenic gold targets in the Central Lapland Greenstone Belt
Kuotko area
Suurikusikko
Saattopora
LevijärviLuokinen
Suurikusikko – Europe`s largest gold producer, Kistala shear zone, typical orogenic gold deposit
Kuotko area – typical orogenic gold with some atypical features, higher metamorphic grade
at the northern termination of the Kistala shear zone
Levijärvi-Luokinen – orogenic gold deposits with atypical metal associations at the conjunction
of the Kistala and Sirkka shear zones
Saattopora – orogenic gold deposit with some atypical features along the Sirkka shear zone
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Ore geology seminar 02.02.2015