developments of the mineral systems and mineral ... · developments of the mineral systems and...

Developments of the Mineral Systems and Mineral Prospectivity Mapping (MinSysPro) project in

Finnish Lapland

Ferenc Molnár

Geological Survey of Finland

Minerals – Source for growth , 03.06.2016 MINSYSPRO Project

Subjects of Presentation

• Background of the project: aims and objectives

• The mineral system approach and mineral prospectivity mapping

• The MINSYSPRO consortium: research teams, international cooperation, research methods

• Orogenic gold mineral systems in Finnish Lapland - targets - current results

Native gold

Rompas


Aims and Objectives of the MinSysPro Project

Development of a knowledge-based and cost effective exploration method which is capable of predicting mineral resources under cover.

Systematic collection of new knowledge of processes leading to formation of orogenic gold and magmatic sulphide/oxide mineral systems in Finnish Lapland by application of modern, cutting edge research methods. Development methods of computer-based conceptual and empirical mineral prospectivity mapping by using the new results of research on mineral systems in Lapland.


Mineral Systems and Models for Mineral Prospectivity Mapping

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 Target generation -incorporation of mappable parameters of mineral system models into mineral prospectivity evaluations

approach

modeling

prospecting

ore components


Vectors to ore

Conditions of primary and secondary enrichment

or dispersion of metals

Mineral Systems: Critical Processes and Parameters

Parameters

Structural control

Geodynamic setting

Relative and absolute timing of processes

Processes

Applicable to magmatic and hydrothermalmineral systems


Selection of the relevant data

based on the exploration model

or mineral system model

Spatial analysis

Validation, targeting

Mineral Prospectivity Mapping

Input pattern generation

V. Nykänen


Orogenic Gold Mineral systems

Ferenc Molnár Hugh O`Brien Peter Sorjonen-Ward Sayeb Muhammad Postdoctoral researchers: Alexander Middleton from 01.01.2015 to 05.02.2016

Matti Kurhila from 01.05.2016 to 30.01.2017

Antonin Richard Univ. Lorraine

Iain Pitcairn Univ. Stockholm

Harry Oduro Gareth Izon Univ. St. Andrews

Holly Stein Univ. Oslo Univ. Colorado

Jussi-Petteri Suuronen The European Synchro- tron Radiation Facility

Mineral Prospectivity Mapping

Vesa Nykänen Satu Mertanen Tero Niiranen Eeva-Lisa Laine Ilkka Lahti Jouni Lerssi Postdoctoral researcher: T.B.N. from 01.08.2016 to 30.08.2018

Magmatic Mineral Systems

Eero Hanski Shenghong Yang Markku Pirttijärvi Hannu Huhma Tuomo Karinen Tuomo Törmänen Yann Lahaye PhD students: Jukka Konnunaho Marko Moilanen Kirsi Luolavirta Fangfang Guo

Wolfgang Maier Univ. Cardiff

Richard Walker Igor Puchtel Univ. Maryland

Wenjun Qu Xiaoping Xia Chinese Acad. Sci.

Sergei Svetov Artem Mokrushin Paul Priprachkin Russian Acad. Sci.

Industry partners Agnico-Eagle Finland Oy. Dragon Mining Oy. Mawson Reosurces Oy. First Quantum Oy. Anglo-American Plc.

Research Consortium


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http://www.first-quantum.com/Home/default.aspx

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 Methods Applied to the Mineral System Research

• In situ analyses of individual minerals with high spatial resolution (micrometer scale)

• Multiple stable and radiogenic isotope, trace element and fluid inclusion analyses from the same sample and even from the same mineral grain.

• Research on the applicability of unconvetional stable and radiogenic isotope systems in better understandig ore- forming processes.

H. O`Brien, Y. Lahaye


Tragets of Research: Orogenic Gold Mineral Systems in Lapland

Examples presented: Multiple hydrothermal processes – geochronology Sources of fluids, vectoring – isotopes, trace elements in minerals Structural control on mineralisation – MicroCT


Granite 1.84-1.80 Ga

Garnet Sm-Nd cooling age

1.75 Ga

Mafic volcanic (amphibolite) unit surrounded by calc-silicate and mica schist units Lower amphibolite facies Svecofennian metamorphism F1 folding: E-W compression; F2 folding: N-S compression Occurrence of black shales in the vicinity of the mineralization

Unusually high concentrations of gold are strictly associated with uraninite and pyrobitumen.

Regional and local geology:

Rompas Au-U mineralization Rompas

Rajapalot Palokas

Undeformed granite intrusions

Migmatite leucosomes

1.78 Ga


Pyrobitumen with uraninite grains

Uraninite with galena and gold

Calcite

Gold

The Uraninite-Gold and Gold-Pyrobitumen Association in the Rompas Property

Pyrobitumen Uraninite

Galena

Altaite

Gold + hunchunite

Gold

Gold-hunchunite-galena-altaite in fractures of uraninite and pyrobytumen

Gold in pyrobitumen and in the shrinkage cracks of pyrobitumen

Gold

Gold

Precipitation of gold post-dates accumulation of pyrobitumen.


0.0

0.2

0.4

0.6

0 2 4 6 8 10 12

207Pb/235U

20

6P

b/2

38U

600

1000

1400

1800

2200

2600

data-point error ellipses are 2s

Lower intercept at 416±85

Upper intercept at 1993±20 [±21] MaMSWD = 0.86; probability of fit = 0.55

U-Pb Ages for Uraninite, Rompas

core

rim

Single grain core

rim

1993 ± 20 Ma

0.0

0.2

0.4

0.6

0 2 4 6 8 10 12

207Pb/235U

20

6P

b/2

38U

600

1000

1400

1800

2200

2600

Lower intercept at 90±270 &MaUpper intercept at 1813±23 [±24] MaMSWD = 1.04; Probability of fit = 0.41


Grains with Low U/Th ratio 1813 ± 23 Ma

0.0

0.2

0.4

0.6

0 2 4 6 8 10 12

207Pb/235U

20

6P

b/2

38U

600

1000

1400

1800

2200

2600

Intercepts at

521±390 & 2095±110 MaMSWD = 2.2; Probability of fit = 0.008


Grains with High U/Th ratio 2095 ± 110 Ma


Re, ppm 187Os, ppb Age, Ma

303 (2) 5722 (5) 1778 ± 13

320.8 (4) 6077 (5) 1782 ± 6

1.581 (5) 33.80 (3) 2007 ± 9

70.7 (1) 1538 (1) 2043 ± 8

109.6 (2) 2362 (2) 2023 ± 7

376.8 (5) 8548 (7) 2128 ± 8

135.1 (2) 3124 (2) 2168 ± 8

uraninite

molybdenite

molybdenite grains drilled out

Four Rompas Molybdenites

Palokas

Molybdenite Re-Os Ages at Rompas and Palokas


The Au-U Mineralisation at Rompas is a

Result of a ≈350 Ma Long Geological Evolution


Preparation of traps for precipitation of

gold

Xenotime

Monazite

Xenotime

Xenotime

aspy

nat. Bi

nat. Au

po

Repeated Hydrothermal Events Along the Same Regional Structure: U-Pb Dating of Hydrothermal Xenotime and Monazite,

Iso-Kuotko, Central Lapland Greenstone Belt

Iso-Kuotko Au-deposit

In situ LA ICPMS analyses with high spatial resolution

Xenotime

Stage 1: 1854-1862 Ma Stage 2: 1757-1768 Ma

Laser-ablation spots of analyses


Sources of Fluids: Sulphur-Isotope Data Central Lapland Greenstone Belt

Hanski, 2005



Development Tools For Vectoring Towards Ore: Trace Elements and Sulphur Isotopes in Pyrite and Other Sulphides

Example: Suurikuusikko gold deposit

Zoning in pyrite: in situ LA ICPMS analyses of trace elements and sulphur isotopes

Sulphur isotope data and Au-contents in pyrite analysed from the same spots

3D distribution of auriferrous arsenopyrite

and pyrite in the host rock.

X-ray computed microtomography.

3D distribution of gold grains and mineral inclusions in arsenopyrite.

Synchrotron radiation based nanotomography.

3D Micro- and Nanoscale Analysis of the Structural Control on Distribution of Ore Minerals

Suurikuusikko gold deposit

M. Sayab


MinSysPro Project - Summary

• Systematic and multidiciplinary research based on the holistic mineral system approach.

• Filling up gaps of knowledge of geological processes which led to the economically importand precious-, base- and critical metal mineral resources in Finnish Lapland.

• Development of new mineral system models and mineral prospectivity mapping methods for better evaluation of targets for mineral exploration


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