The Tectonics, Geology and Gold-Copper Metallogeny of New Guinea

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1 The Tectonics, Geology and Gold-Copper Metallogeny of New Guinea STEVE GARWIN Independent Consultant Grasberg open-pit, circa th March, 2015 PACRIM 2015, Hong Kong China

2 Tectonic Elements, Cenozoic Magmatic Arcs and Major Au-Cu Deposits Shown on Sea-floor Bathymetry and DEM SE Asia and the W Pacific (Garwin et al., 2005 and Garwin, 2013)

3 GOLD DEPOSITS AGE & GOLD CONTENT SE Asia and the W Pacific Gold Content (tonnes) Wafi Golpu Age (million years)

4 Copper Content (1000 s tonnes) COPPER DEPOSITS AGE & Cu CONTENT SE Asia and the W Pacific Wafi Golpu (9000) Age (million years)

5 New Guinea Tectonic Framework Structural Preparation to Au-Cu mineralization Major plate reorganizations at c. 25 Ma and 5 Ma Maramuni arc and Medial New Guinea magmatic belt Miocene to Pleistocene magmatism (~ 20 1 Ma) Au-Cu mineralization from about 14 to 1 Ma Arc-transverse fault zones that control magmatism structural link to the mantle Mineralization follows southerly propagation of thrust-front Fault inversion along craton margin & crustal delamination Region of contraction / uplift / exhumation Structural settings favorable to focus heat- and fluid-flow

6 Tectonic Framework for New Guinea Presentday Wafi >10 M Oz Au Resource > 5 M Oz Au Resource Medial New Guinea Magmatic Belt (6 1 Ma) Maramuni Arc (Miocene) (Garwin et al., 2005; Garwin, 2013)

7 Major Gold and Copper Deposits / Districts (Garwin et al., 2005) >10 M Oz Au Resource > 5 M Oz Au Resource

8 New Guinea Regional Tectonic Setting Presentday >10 M Oz Au Resource > 5 M Oz Au Resource (Hall, 2002 and Garwin et al., 2005)

9 New Guinea Tectonic Reconstruction 25 Ma Arcs begin to collide with Australian plate. Ontong Java plateau collides with Melanesian arc. Sula Spur collides with Sundaland. PSF initiated In Bird s Head. (Hall, 2002 and Garwin et al., 2005)

New Guinea Tectonic Reconstruction 15 Ma SF splays cause collisions in eastern Sulawesi. S. Caroline arc terranes collide with New Guinea, but move in a leftlateral strike-slip zone.

10 New Guinea Tectonic Reconstruction 15 Ma SF splays cause collisions in eastern Sulawesi. S. Caroline arc terranes collide with New Guinea, but move in a leftlateral strike-slip zone. Subduction of the Solomon Sea beneath eastern New Guinea forms the Maramuni arc (c. 20 Ma). (Hall, 2002 and Garwin et al., 2005)

New Guinea Tectonic Reconstruction 5 Ma Bismarck sea opens. Woodlark basin spreading begins. Further accretion of arc terranes and significant uplift of mountains.

11 New Guinea Tectonic Reconstruction 5 Ma Bismarck sea opens. Woodlark basin spreading begins. Further accretion of arc terranes and significant uplift of mountains. Hinge rollback at the western end of New Guinea induces spreading in the Banda sea. (Hall, 2002 and Garwin et al., 2005) Australian craton approaches Indonesia, before collision with Banda arc at ~ 4 to 3 Ma.

12 New Guinea Tectonic Model Jurassic Architecture (Hill and Hall, 2003)

25 Ma Oblique subduction of the Solomon sea plate gave rise to Maramuni arc in eastern New Guinea.

13 New Guinea Tectonic Models 25 and 15 Ma Arc collision with the continental margin of Australia. New Guinea margin changes from convergent to strike-slip dominant. 25 Ma Oblique subduction of the Solomon sea plate gave rise to Maramuni arc in eastern New Guinea. No south-dipping slab in western New Guinea at this time; a remnant slab may have dipped towards the north in Indonesia. 15 Ma Wafi, Freida (Hill and Hall, 2003)

Convergence of the Caroline arc with New Guinea from about 12 Ma causes thrusting in the mobile belt and fold belt but ongoing

14 New Guinea Tectonic Models 5 and 3-2 Ma 5 Ma Variable crust types effect extent of thrusting and uplift in western and eastern New Guinea. Convergence of the Caroline arc with New Guinea from about 12 Ma causes thrusting in the mobile belt and fold belt but ongoing strike-slip motion between the mobile belt and the accreted arc terranes. Plio-Pleistocene: local extensional reactivation of NEtrending basement faults provides link to mantle. Compression gives way to strike-slip faulting at 3-2 Ma. 3-2 Ma (Hill and Hall, 2003)

15 Papua New Guinea and Papua, Indonesia Au (Cu) Deposits and Settings (Garwin et al., 2005) Golpu >10 M Oz Au Resource > 5 M Oz Au Resource

16 Papua New Guinea Basement Faults and Cross- Sructures >10 M Oz Au Resource (Hill, 1991 and Gow and Walshe, 2005)

17 Neogene Thrust Inversion of Mesozoic Extensional Faults in Cratonic Basement Porgera Example (~ 6 Ma) (Hill et al., 2002)

18 Geodynamic Model for Structural Setting to Pliocene Cu-Au Deposits in Papuan Fold Belt of New Guinea (Hill et al., 2002)

19 Deposit and Magmatic Ages Versus Distance from Leading Basement Thrust 22 Maramuni Frieda 7 6 Wabu Porgera MNG 1 (Hill et al., 2002) and Davies (1991) Uplift / Exhumation rates of 0.7 to 1.7 mma- 1

20 Lithospheric-scale Cross Section for Central Range, Papuan Fold Belt Western New Guinea at 6 Ma. Comments Delamination commences at ~ 8 Ma and ceases at ~ 4 Ma ~ 1 mma 1 Thick-skinned Imbrication of cont. basement Craton GB PG Fold and Thrust Belt Thin-skinned Mapenduma anticline forms above reactivated normal faults Lithospheric mantle Asthenospheric mantle Transitional crust Mafic / alkaline magma pools near base of craton Early Jurassic oceanic crust Removal of lith. mantle leads to isostatic uplift (Cloos et al., 2005) Ideal setting for focused heatflow and intrusion-related mineralization

21 New Guinea Tectonic Framework Structural Preparation to Au-Cu Mineralization Major plate reorganizations at c. 25 Ma and 5 Ma Maramuni arc and Medial New Guinea magmatic belt Miocene to Pleistocene magmatism (~ 20 1 Ma) Au-Cu mineralization from about 14 to 1 Ma Arc-transverse fault zones that control magmatism structural link to the mantle Mineralization follows southerly propagation of thrust-front Fault inversion along craton margin & crustal delamination Region of contraction / uplift / exhumation Structural settings favorable to focus heat- and fluid-flow

22 New Guinea Gold-Copper Deposits Favorable Geological and Structural Settings Dilational zones in long-lived fault systems Zones of intersection between basement faults Basement high / dome / large-scale folds / horst-block Batholith / horst margins in zones of low mean-stress Reactive carbonate host-rocks as depositional traps

23 REFERENCES Carlile, J. C., and Mitchell, A. H. G., 1994, Magmatic arcs and associated gold and copper mineralization in Indonesia, in van Leeuwen T. M., Hedenquist, J. W., James, L. P., and Dow, J. A. S., eds., Mineral deposits of Indonesia; discoveries of the past 25 years., Journal of Geochemical Exploration v. 50; 1-3, p Cloos, M., Saphie, B., van Ufford, A.Q., Weiland, R.J., Warren, P.Q., and McMahon, T.P., 2005, Collisional delamination in New Guinea: The geotectonics of subducting slab breakoff, Geological Society of America, Special Paper 40, 50 p. Corbett, G. J., 1994, Regional structural control of selected Cu/Au occurrences in Papua New Guinea, in Rogerson, L., ed., Proceedings of the Papua New Guinea Geology, Mining and Exploration Conference: Lae, Australasian Institute of Mining and Metallurgy, Melbourne, p Corbett, G.J., and Leach, T.M., 1998, Southwest Pacific Rim gold-copper systems: Structure, alteration and mineralization, Society of Economic Geologists Special Publication 6, 240 p. Crowhurst, P. V., Hill, K. C., Foster, D. A., and Bennett, A. P., 1996, Thermochronological and geochemical constraints on the tectonic evolution of northern Papua New Guinea, in Hall, R., and Blundell Derek, J., eds., Tectonic evolution of Southeast Asia., 106. Geological Society Special Publications: London, United Kingdom, Geological Society of London, p Davies, H. L., 1991, Regional geologic setting of some mineral deposits of the New Guinea region, in Rogerson, R., ed., Proceedings of the Papua New Guinea Geology, Exploration and Mining Conference: Rabaul, Australasian Institute of Mining and Metallurgy, Melbourne, p Dow, D. B., 1977, A geological synthesis of Papua New Guinea: Australian Bureau of Mineral Resources Bulletin 201, Geology and Geophysics, 41 p. Dow, D. B., and Sukamto, R., 1984, Western Irian Jaya; the end-product of oblique plate convergence in the late Tertiary: Tectonophysics, v. 106, p

24 REFERENCES Fischer, M. W., and Warburton, J., 1996, The importance of pre-tertiary basin architecture for hydrocarbon accumulation in the Papuan fold and thrust belt; models, analogues and implications, in Buchanan Peter, G., ed., Petroleum exploration, development and production in Papua New Guinea; proceedings of the third PNG petroleum convention, Port Moresby, Papua New Guinea, PNG Chamber of Mines and Petroleum, p Garwin, S., Hall, R., and Watanabe, Y., Tectonic setting, geology and gold and copper mineralization in Cenozoic magmatic arcs of Southeast Asia and the west Pacific, in Hedenquist, J., Goldfarb, R. and Thompson, J. (eds.), Economic Geology 100 th Anniversary Volume, Society of Economic Geologists, p Garwin, S., 2013, Tectonic and structural controls to porphyry and epithermal mineralization in the Cenozoic magmatic arcs of Southeast Asia and the West Pacific, in Vearncombe, J. (compiler), Bulletin No. 57, Australian Institute of Geoscientists Symposium, May, 2013, Bali, Indonesia, p Gow, P.A., and Walshe, J.L., The role of pre-existing geologic architecture in the formation of giant porphyryrelated Cu + Au deposits: examples from New Guinea and Chile, Economic Geology, Society of Economic Geologists v. 100, pp Hall, R., 2002, Cenozoic geological and plate tectonic evolution of SE Asia and the SW Pacific: computer-based reconstructions, model and animations: Journal of Asian Earth Sciences, v. 20, p Hamilton, W., 1979, Tectonics of the Indonesian region: U.S. Geological Survey Professional Paper, v. 1078, p. 345 p. Hill, K. C., Kendrick, R. D., Crowhurst, P. V., and Gow, P. A., 2002, Copper-gold mineralisation in New Guinea; tectonics, lineaments, thermochronology and structure, in Korsch, R. J., ed., Geodynamics of Australia and its mineral systems; technologies, syntheses and regional studies, Blackwell Scientific Publications for the Geological Society of Australia. Melbourne, Australia, p Hill, K.C., and Hall, R., 2003, Mesozoic-Cenozoic evolution of Australia's New Guinea margin in a west Pacific context, Geological Society of America Special Papers, v. 372, p

25 REFERENCES Hutchison, C.S., 1989, Geological Evolution of Southeast Asia, Oxford Monographs on Geology and Geophysics, 13, Carendon Press, Oxford, United Kingdom, 368 p. McDowell, F. W., McMahon, T. P., Warren, P. Q., and Cloos, M., 1996, Pliocene Cu-Au-bearing igneous intrusions of the Gunung Bijih (Ertsberg) District, Irian Jaya, Indonesia; K-Ar geochronology: Journal of Geology, v. 104, p Pigram, C. J., and Davies, H. L., 1987, Terranes and the accretion history of the New Guinea Orogen: BMR Journal of Australian Geology and Geophysics, v. 10, p Rogerson, R., and McKee, C., 1990, Geology, volcanism and mineral deposits of Papua New Guinea, in Hughes, F. E., ed., Geology of the mineral deposits of Australia and Papua New Guinea; Volume 2., 14. Monograph Series - Australasian Institute of Mining and Metallurgy: Melbourne, Victoria, Australia, Australasian Institute of Mining and Metallurgy, p Sillitoe, R.H., and Hedenquist, J. W., 2003, Linkages between volcanotectonic settings, ore-fluid compositions, and epithermal precious-metal deposits, in Simmons, S. F., and Graham, I., eds., Giggenbach Volume, Special Publication 10, Society of Economic Geologists and Geochemical Society, p Weiland, R. J., and Cloos, M., 1996, Pliocene-Pleistocene asymmetric unroofing of the Irian fold belt, Irian Jaya, Indonesia; apatite fission-track thermochronology: Geological Society of America Bulletin, v. 108, p

Tectonic and Structural Controls to Porphyry and Epithermal Mineralization in Cenozoic Magmatic Arcs of SE Asia and the W Pacific

Tectonic and Structural Controls to Porphyry and Epithermal Mineralization in Cenozoic Magmatic Arcs of SE Asia and the W Pacific STEVE GARWIN Independent Consultant sgar@iinet.net.au Grasberg, 24 Mt Cu