Department of Natural Resources and Mines Mineral Systems modelling in the Mount Isa Inlier, and its use in identification of permissive tracts for copper and lead/zinc mineralisation. L.J.Hutton Geological Survey of Queensland Queensland Department of Natural Resources and Mines
Mineral Systems modelling: Answering the five Questions What is the geodynamic setting? What is the architecture of the system? What are the fluids, their sources and reservoirs? What are the fluid flow drivers and pathways? What are the metal transport and deposition processes? 2
Background Strategies to harness these opportunities.. Smart use of data + Collaboration to maximise benefit and support Active and Effective Exploration North West Queensland Mineral and Energy Province (NWQMEP) a world class exploration destination >70% undercover 3
APPROACH (1) Geodynamic Setting 4
(1) Big picture Reviewing NWQMEP in the Australian Continent 5
(1) Big picture Geodynamic & tectonic setting Tectonic interpretations at a continental scale for the region are speculative and in some aspects contentious.. 6
(1) Big picture Geodynamic & tectonic setting Tectonic setting and associated architecture are first order indicators of resource potential 7
(1) Big picture Geodynamic synthesis The geodynamic model has implications for fundamental controls on mineralisation: Reconciling interpretation of events and deformation responses 8
APPROACH Geodynamoic Setting 2) Architecture 9
(2) Subsurface geology integrating geology and advanced geophysical processing New Data + Modern Modelling Techniques magnetotelluric, new and reprocessed seismic datasets, open file company data updated mapping/structural interpretations depth to basement modelling forward modelling and geophysical inversion 10
(2) Subsurface geology Depth to Basement Modelling Identify zones of shallow cover Datasets: Water bores, Petroleum Wells and Mineral Exploration Holes Magnetic profile modelling SPI magnetic modelling Seismic DEM 11
(2) Subsurface geology 3D visualisation Update 3D model - integrating new regional interpretations Extending from outcropping areas to interpretation undercover Reconciling diverse data sets sensible and consistent model 12
(2) Subsurface geology - a range of scales District scale Mount Dore region Cu-Au-Fe (Mo-Re) 13
Summary strategy 2: DATA INPUT PROCESSING INTERPRETATION OUTPUT 14
APPROACH (1) Geodynamic Setting (2) Architecture (3) Fluids, their sources and reservoirs 15
Mineral Systems Pb/Zn Systems Western Fold Belt Shale Hosted Pb/Zn Cu Systems Western Fold Belt Sedimentary hosted Cu deposits Eastern Fold Belt Cu/Au systems (IOCG) 16
Shale Hosted Pb/Zn Systems (Western Fold Belt) 17
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Cu Systems 20
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APPROACH (1) Geodynamic Setting (2) Architecture (3) Fluids, their sources and reservoirs (4) Fluid flow drivers and pathways 22
Cu Deposits: Mount Isa Inlier 23
Some large mineral deposits occur adjacent to deep graben bounding normal faults; Identification of the margin of the Leichhardt River Fault trough; Mount Gordon Arch Line 06GA M3 24
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Inversion Events Pb/Zn systems occur within smaller rift systems and are expelled during local inversions don t need regional deformations. Look for evidence of intra-graben inversions (change in sedimentary sources) Pb/Zn mineralisation is syn-sedimentary or early diagenetic (~1650Ma) Cu systems fluids form deep crustal sources need regional deformations to expel fluids. In the Eastern succession fluid expulsion occurs during magmatic events In the Western fold belt expulsion occurs during Isan events Cu mineralisation is related to deformations (~1530 Ma) 26
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Conclusions The sequence at Mount Isa is deposited in a series grabens Fluid pathways focus on early formed ( grabenbounding) structures Pb/Zn sources are within the supracrustal sequences Don t need deep structures or regional inversion Cu sources are initially deep and need mechanisms to get fluids into the supracrustal environment. Two mechanisms are envisaged Deep structures in the Western Fold Belt Igneous intrusion in the Eastern Fold Belt 28
Department of Natural Resources and Mines