Intrusion-related mineral systems of north-east Queensland 3-year collaborative research project

Transcription

1 Intrusion-related mineral systems of north-east Queensland 3-year collaborative research project Vladimir Lisitsin (Geological Survey of Queensland) Gregg Morrison (Klondike Exploration) Simon Beams (Terra Search) Zhaoshan Chang (James Cook University)

2 Acknowledgements The presentation was prepared by V. Lisitsin (GSQ) - but the conceptual framework of the discussed project had been defined through extensive consultations involving many people most notably, from JCU, Terra Search and Klondike Exploration Most sample- to deposit-scale illustrations of intrusionrelated gold deposits were provided by Gregg Morrison (Klondike Exploration)

3 Outline Project background Major intrusion-related (and other) mineral systems of NE QLD an overview Geological problems and questions Proposed solutions - project scope and implementation

4 Project background Industry Priorities initiative of Queensland Government announced in June 2013 Projects selected on the basis of evaluation of proposals submitted through QEC, AMEC and APPEA Assessing prospectivity of intrusion-related mineral systems in north-east Queensland a 3-year collaborative project, commenced in July 2014 Essential pre-history - >20 years of research (AMIRA, JCU) and active exploration and mining in the region

5 U North-east Queensland significant mining history Significant historic production and remaining resources of various commodities: W Sn Gold-silver Charters Towers (6.5 Moz), Kidston (5 Moz), Pajingo (5 Moz), Ravenswood (4 Moz), Mungana Red Dome (4 Moz), Mt Leyshon (3.5 Moz), Mt Carlton (>2.2 Moz eq.), Palmer (1.5 Moz), Mt Wright (1.3 Moz) Ni, Co Fe U Tin-tungsten Herberton, Mt Carbine Uranium Ben Lomond, Maureen, Ag, Ag Nickel Greenvale

6 U North-east Queensland rare recent discoveries? Relatively limited current activity outside several major projects W Sn Ni, Co Fe U, Ag, Ag Few significant recent discoveries Have we run out of resources or ideas? What exploration strategies worked in the past and what may work now? We need to re-evaluate mineral prospectivity of the region and find ways to unlock it

7 North-east Queensland discovery history U W Sn Ni, Co Fe U Early discoveries: Etheridge (1869), Charters Towers (1871), Palmer (1872), Herberton Sn (1880) Early discovery late recognition: Kidston ( s), Mt Wright ( ), Mt Leyshon (1880-s 1980-s) Modern story: Pajingo (1983) Mt Carlton (1980-s 2006) All major discoveries mineralisation in the outcrop, Ag, Ag

8 North-east Queensland occurrences of various commodities over a large region Occurrences of economically significant (in the past and present) commodities over large areas, Sn-W, Ag- Zn-Pb, Cu Significant overlaps of different commodities particularly -Ag, but also -Sb, Cu-, -Sn-W

9 North-east Queensland occurrences of various commodities over a large region Occurrences of economically significant (in the past and present) commodities over large areas, Sn-W, Ag- Zn-Pb, Cu Significant overlaps of different commodities particularly -Ag, but also -Sb, Cu-, -Sn-W

10 North-east Queensland occurrences of various commodities over a large region Occurrences of economically significant (in the past and present) commodities over large areas, Sn-W, Ag- Zn-Pb, Cu Significant overlaps of different commodities particularly -Ag, but also -Sb Cu-, -Sn-W Difficult to analyse, incomplete data, no information under cover

11 North-east Queensland regional-scale mineral systems Multitude of known mineral occurrences of different commodities and diverse mineralisation styles Multitude of detailed deposit-scale studies at a few major and select smaller deposits Using concepts of regional mineral systems can assist in regional-scale metallogenic analysis and exploration targeting

12 Mineral systems conceptual definition All geological factors that control the generation and preservation of mineral deposits (Wyborn et al., 1994) An emphasis on a combination of individual critical processes and their spatial expressions and general concepts used in a prospectivity analysis Spatial scale tens to hundreds of kilometres A mineral system can include deposits with different main commodities and of various deposit styles

13 Mineral system example Intrusion-Related Gold NB: A district not the whole regional system (Hart, 2005)

14 North-east Queensland gold mineralisation Gold-bearing occurrences are widespread throughout the region They represent multiple deposit types and styles, formed during different geological events Different mineralisation controls are likely

15 North-east Queensland gold mineralisation of various styles Gold-bearing occurrences represent multiple deposit types and styles: Cainozoic alluvial Ordovician VHMS Early Devonian intrusionrelated veins Carboniferous to Permian orogenic gold veins Carboniferous to Permian epithermal, porphyry, skarn, subvolcanic breccia and intruison-related veins

16 Orogenic gold mineral systems north-east Queensland Deposits consistent with the definition of orogenic gold mineral systems are common in the Mossman Orogen, at Charters Towers and Etheridge Orogenic gold mineral systems at Charters Towers and Etheridge spatially overlap with younger intrusion-related mineral systems potential for confusing exploration

17 Orogenic gold mineral systems north-east Queensland Deposits consistent with the definition of orogenic gold mineral systems are common in the Mossman Orogen, at Charters Towers and Etheridge Orogenic gold mineral systems at Charters Towers and Etheridge spatially overlap with younger intrusion-related mineral systems potential for confusing exploration

18 Orogenic gold mineral systems north-east Queensland Major orogenic gold mineral systems: Early Devonian Charters Towers Etheridge Carboniferous to Early Permian Hodgkinson Broken River Coeval mineral systems may have been genetically related and spatially contiguous

19 Permo-Carboniferous intrusion-related mineral systems Diverse deposits throughout the region show close genetic relationships with Permo-Carboniferous magmatism Magmatic rocks of the Kennedy Igneous Association are particularly widespread and metallogenically important

20 Permo-Carboniferous intrusion-related mineral systems 320 Ma 303 Ma 330 Ma 330 Ma 306 Ma 280Ma 342 Ma 310 Ma 266 Ma Geochronology available for major deposits no data for the bulk of Permo- Carboniferous(?) mineralisation Clear indications of multiple metallogenic events several distinct mineral systems? Do they have different controls and different prospectivity?

21 Permo-Carboniferous magmatic-related mineral systems Diverse deposits throughout the region show close genetic relationships with Permo-Carboniferous magmatism They are likely to represent an extensive family of related hydrothermal mineral systems, such as: Sn-W Intrusion-related Epithermal -Ag Porphyry Mo-Cu

22 Magma redox and fractionation 10 1 Fe 2 O 3 / FeO Cu- W Increasing oxidation Increasing fractionation Cu-Mo W-Mo Mo Sn Sn±W Rb/Sr

23 METAL ZONING PATTERNS AND ORE POSITION FOR PORPHYRY HYDROTHERMAL SYSTEMS DISTAL PROXIMAL CORE Cadia Ca As Sb Pb Zn Ag (Cu Mo Te) Cu (Zn) Mt Leyshon Ca (As Sb ) Pb Zn Ag ( Bi) Bi Ag (Cu Te) Kidston F, U As Ag Sb Bi Zn (Pb Cu) Cu ( Bi Te) DEPOSIT TO DISTRICT SCALE FRACTIONATION PROVINCE SCALE Best Blevin & Morrison 1997

24 Permo-Carboniferous magmatic-related mineral systems Metallogenic specialisation of major Permo- Carboniferous magmatic complexes, based on their dominant geochemistry Theoretical explanation of empirical observations Blevin, 2003

25 Intrusion-Related Gold deposits - NQ

26 Mt Leyshon Breccia Ore Normal-low grade: 1-2g/t Partial cavity fill High-grade: Cavity fill Veinlets & High-grade veins > 10g/t

27 Kidston magmatic links

28 Mt Wright Granite mush BX Polymict BX Granite BX (cavity fill) Tuffisite w/ rhyolite BX Tuffisite* Granite mush (deep) 28

29 Kidston - Metal Zoning Porphyry Mo-W-Bi Confined in breccia pipe Overall zoning on a Thermal gradient only above sill With Pb-Zn-Cu Another boiling phase Fluid segregation confinement & Pressure drop boiling Cause of ore

30 IntrusionRelated Gold Systems North Queensland perspective Most major intrusion-related gold deposits in the region represent local expressions of only a few regional mineral systems

31 31 Questions and problems Spatial extents of specific intrusion-related mineral systems and their geochemical variants? Geochronology of metallogenic and associated magmatic events across the region? Distinguishing barren, poor and rich systems and districts? Recognising potential at depth? Mineralogical and geochemical alteration signatures early recognition of hydrothermal alteration? Geophysical expressions in regional and more detailed datasets? Consistent validated regional metallogenic datasets geochemistry, shallow intrusions, solid geology? Exploration targeting strategies, tools and targets?

32 Exploration geophysics signatures? Magnetic anomalies can be variable. Ore stage alteration usually mag. destructive. Complicated by other features such as: Intrusive plugs / dykes Pyrrhotite (or magnetite) mineralisation Low primary susceptibility of host Mount Leyshon: Strong reverse polarised feature immediately south of deposit Related to bt-mt alteration/hornfels associated with southern porphyry Feature not directly related to mineralisation stage 5km Lisowiec and Morrison, Kidston: No obvious magnetic feature (at regional scale) Felsic intrusions in felsic host.

33 Charters Towers 100k geology: Ordovician Granodiorite

34 Actual geology multiple intrusive phases events

35 Permo-Carboniferous intrusion-related mineral systems The Permo-Carboniferous magmatic-related mineral systems remain poorly understood A collaborative 3-year project between GSQ, JCU, Terra Search and Klondike Exploration has commenced in July 2014 under the Industry Priorities initiative of Queensland Government

36 Prospectivity of intrusion-related mineral systems of north-east Queensland Funding: $2.5 million over 3 years from GSQ, plus in-kind contributions from the collaborative partners and additional funding from industry Scope: 11 related sub-projects Governance: Steering Committee (chaired by GSQ) Project manager (appointed by GSQ) Sub-project managers (appointed by JCU and Klondike-Terra Search)

37 Project structure Title Responsible group 1. Magma-related hydrothermal mineral systems of the northern Bowen Basin JCU 2. Geology of the Mt Carlton high-sulfidation epithermal deposit JCU 3. Magma fertility, petrogenesis and geodynamic setting of Carboniferous and Permian magmatic complexes JCU 4. Updated geology of the Charters Towers region TS-K 5. Metallogeny of the Charters Towers Province TS-K 6. Metallogeny of the Permo-Carboniferous mineral systems of the Georgetown region TS-K 7. Metallogeny of Sn-W-Mo-Cu mineral systems JCU 8. Exploration geophysical signatures of intrusion-related deposits in the Charters Towers region TS-K 9. Comprehensive prospectivity analysis JCU - GSQ 10. Regional alteration mapping using remote sensing methods JCU 11. Geochemical signatures of intrusion-related mineral systems JCU - TS-K

38 Summary Diverse mineral systems of north-east Queensland have a significant potential for major new discoveries A large-scale collaborative study to evaluate the mineral potential of the region and to facilitate the new discoveries are currently under way and will continue in the next few years ( ) Geological Survey of Queensland James Cook University Terra Search Klondike Exploration vladimir.lisitsin@dnrm.qld.gov.au zhaoshan.chang@jcu.edu.au admin@terrasearch.com.au greggmorrison@oz .com.au