1. No category

Mineral Systems
in Mineral Potential Evaluation
Ferenc Molnár
STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI
www.gtk.fi
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
www.gtk.fi
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
www.gtk.fi
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
www.gtk.fi
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
www.gtk.fi
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
www.gtk.fi
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
www.gtk.fi
Ore geology seminar 02.02.2015
Workflow of the Project
New targets for
mineral exploratiom
www.gtk.fi
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
www.gtk.fi
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
STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI
100s µm
BSE image, sulfides (bright) in primary silicates
(med grey) with alteration (dk gray)
www.gtk.fi
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.
STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI
www.gtk.fi
Source of Fluids
Boron Isotopes in Tourmaline , Hattu Schist Belt, Eastern Finland
Metasedimentary
Tourmaline veining in intrusive rocks
Massive tourmalinization in
metasedimentary units
STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI
www.gtk.fi
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
STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI
www.gtk.fi
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?
-
STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI
Tonalite
weak alteration
Geophysical response?
www.gtk.fi
Mappable Criterias – Geophysical Response
Petrophysical Properties of Mineralized Source Rocks and Barren Intrusions
Pampalo Mine, Hattu schist Belt
STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI
www.gtk.fi
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
www.gtk.fi
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
STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI
www.gtk.fi
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
www.gtk.fi
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
www.gtk.fi
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.
www.gtk.fi
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
www.gtk.fi
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
www.gtk.fi
Ore geology seminar 02.02.2015