Mineral Systems in Mineral Potential Evaluation - …en.gtk.fi/export/sites/en/informationservices/... · · 2015-05-19Mineral Systems in Mineral Potential Evaluation Ferenc Molnár

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

www.gtk.fi STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI

Gold

Mineral Systems, Models and Mineral Potential Evaluation


Mineral Systems - all geological factors that control origin and preservation of mineral deposits Mineral System Model - definition of sources transportation accumulation re-mobilisation mappable parameters Mineral potential evaluation -incorporation of mappable parameters of mineral system models into mineral prospectivity evaluations

approach

modeling

prospecting

ore components

Geodynamic processes – Source rocks

Structures

Vectors to ore

Primary and secondary dispersion


Mineral Systems: Critical Processes and Parameters

Accumulation processes

Critical processes

Critical parameters

Geological features

Mappable

criteria

Change in physical state of fluids

Change in chemical state of fluids

Characteristics of fluid/rock interaction

Primary Transportation Deposition Preservation/Re-mobilization mobilization

Alteration mineralogy Rocks with favourable chemistry Chemical gradients

in composition of rocks

Geophysical response Lithogeochemistry Remote sensing response

Processes in Mineral Systems and Mappable Criteria

Modified after McCuaig et al., 2010 Link between mineral system research 3D modeling and mineral prospectivity mapping


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


New targets for mineral exploratiom

Workflow of the Project


Research on Orogenic Gold Mineral Systems:

Outstanding Questions - Examples

Sources of ore forming fluids and components -magmatic, metamorphic, other? 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?

Hattu Schist Belt

Central Lapland Greenstone Belt

Kuusamo Belt Peräpohja Belt


ORE

10-100s km

100s µm

OVERPRINT

REMOBILIZATION

Studies of minerals at the micro scale can be used to decipher processes at the km+ scale

BSE image, sulfides (bright) in primary silicates (med grey) with alteration (dk gray)


Repetition of processes at all scales

Nu AttoM HR-ICP-MS with laser microprobe

Nu Plasma MC-ICP-MS with laser microprobe

JEOL JSM 7100F high resolution

FE-SEM

Mineralogy Geochronology, stable and radiogenic isotopes, trace elements

Linkam MDSG 600 microT

Fluid inclusions

Cutting Edge Analytical Tools Applied in Mineral System Research at GTK

In situ high analyses with high spatial resolution Simple sample preparation – mostly polished thin sections Multiple isotope/trace element/fluid inclusion analyses from the same sample and even from the same mineral grain.


Tourmaline veining in intrusive rocks

Massive tourmalinization in metasedimentary units


Magmatic Metasedimentary

Source of Fluids Boron Isotopes in Tourmaline , Hattu Schist Belt, Eastern Finland

Source of Fluids: Potential Use of Unconventional Stable Isotopes

Hattu Schist Belt, Eastern Finland

Copper and sulphur isotope analyses in chalcopyrite by LA MC ICPMS

Magmatic fluids

Fluids from the metasediments

Further research on -Proterozoic orogenic gold systems - Fe, Zn and Mo isotopes


Tonalite weak alteration

Feldspar porphyry Strong alteration and

disseminated ore

www.gtk.fi

Fluid Sources – Mappable Criterias

ORE No

ORE

STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI

Mappable criteria? - Geophysical response?

2712±4 –2717±8 Ma 2725 ± 12 Ma

Zircon 207Pb-206Pb ages :

Zircon 207Pb-206Pb age

Mappable Criterias – Geophysical Response Petrophysical Properties of Mineralized Source Rocks and Barren Intrusions

Pampalo Mine, Hattu schist Belt


Effect of Remobilisation on the Quality of Ore Pampalo Mine, Hattu schist belt

Ar-Ar thermochronology

Lead isotopes: galena, hydrothermal K-feldspar Late Svecofennian (1.81 Ga) K-metasomatism

Late Svecofennian (1.81 Ga) thermal event

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

Trap 1: uraninite grains

Uranogenic lead in Pb-minerals

Traps for Formation of High Grade Gold Concentration Rompas, Peräpohja Schist Belt

(U,Pb*)O2 UO2 + Pb*2+

2Au(HS)2ˉ + H2 + Pb*2+ 2Au + Pb*S + 3H2S

2Au(HS)2

ˉ+ 2H2 + Pb*2+ Au2Pb* + 4H2S

[Au2Te4]4- + 2H2 + 4Pb*2+ 2Au + 4Pb*Te + 4H+

Trap 2: pyrobitumen nodules

Scavenging of sulphur from gold transporting fluids


Gold

www.gtk.fi

Geochronology of multiple hydrothermal events: Kuotko, Central Lapland Greenstone Belt

Early arsenopyrite bearing mineralization superimposed by native bismuth-gold-pyrrhotite

in veins with multiple carbonate deposition

1739 Ma

1808 Ma

1814 Ma

1822 Ma

1778 Ma

Hydrothermal xenotime from carbonate veins: U-Pb geochronology by LA MC ICPMS

Aspy

Bi

Au

Po

Intercept at 1854 ± 14 Ma MSWD = 0.28

Probablity of fit 0.96

Intercept at 1769 ± 9 Ma MSWD = 0.49

Probablity of fit 0.97

Critical processes of ore formation and preser-vation manifested by mappable geological and geophysical features

Mineral system research

Spatial and temporal dis-tribution of geological features that record critical processes

2D-3D-4D modelling Conceptual and empirical

evaluation of mineral potential and selection of areas for exploration

Mineral prospectivity mapping

STAKEHOLDER SEMINAR, 06 MAY 2015, ROVANIEMI www.gtk.fi

Summary

Research on critical processes and key parameters Models and mineral prospectivity of orogenic gold mineral systems; workgroup 1 mapping, workgroup 3 Ferenc Molnár Vesa Nykänen Hugh O`Brien Satu Mertanen Peter Sorjonen-Ward Tero Niiranen Sayeb Muhammad Eeva-Lisa Laine Antonin Richard (France) Ilkka Lahti Ian Pitcairn (Sweden) Jouni Lerssi Harry Oduro (U.K.) Ilkka Suppala Holly Stein (USA/Norway) Postdoctoral researcher Postdoctoral researcher from 01.01.2015 from 01.09.2016 to 30.08.2018 Alexander Middleton T.B.N.

Research teams: orogenic gold mineral systems and mineral prospectivity mapping


Research teams: magmatic mineral systems

Univeristy of Oulu: GTK: Eero Hanski Hannu Huhma Shenghong Yang Yann Lahaye Markku Pirttijärvi Tuomo Karinen Wolfgang Maier, (U.K.) Jukka Konnunaho Tuomo Törmanen Two Master’s students (2x3 months) Doctoral student First Quantum Oy.: from 01.09.2014 to 30.08.2018 Petri Peltonen Marko Moilanen


Kuotko area

Levijärvi- Luokinen


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

Orogenic gold targets in the Central Lapland Greenstone Belt

Suurikusikko

Saattopora

Documents

Mineral Systems in Mineral Potential Evaluation - …en.gtk.fi/export/sites/en/informationservices/... · · 2015-05-19Mineral Systems in Mineral Potential Evaluation Ferenc Molnár