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Explore the geology, structure, and characteristics of gold mineralization in southern West and South-West Greenland, focusing on orogenic gold deposits and hydrothermal alteration mineralogy. Understand the tectonic models and potential of different gold provinces.
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Orogenic gold mineralisation in the Archean North Atlantic craton, southern West and South-West Greenland Jochen Kolb1, Denis M. Schlatter1, Annika Dziggel2, Alexander F.M. Kisters3 ¹Department of Petrology and EconomicGeology, GeologicalSurvey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark 2Institute of Mineralogy and Economic Geology, RWTH Aachen University, Wüllnerstr. 2, 52064 Aachen, Germany 3Department of Earth Sciences, Stellenbosch University, Matieland 7602, South Africa
increasing intensitiy of alteration Fluid/wallrock reactions Au deposition Diffusion CONDUIT Dispersion SOURCE ROCK hydrothermal alteration Mineralizing system of orogenic gold deposits Ridley et al. 1996 Main devolatilization 440 – 520°C Philipps and Powell 2010 Groves et al. 1993
Gold production vs. gold ages Goldfarbet al. 2001 North Atlantic craton
Geologicalmap of South-West Greenland Paamiut gold province Tartoq gold province
Characteristics of gold mineralization Paamiut gold province • 5 occurrences; 40 km strike • Auriferousquartzveins in higher-orderstructures • Au-only + As, W, Mo, Bi • Ore mineralogy: Po-Apy-Ccp • Hydrothermal alteration mineralogy • ProximalHbl • DistalQtz-Hbl/Oam-Bt-Tur-Ank ± Grt, Ms, Cal • Sulfide-poor(< 5 vol.%) Tartoq gold province • ≥ 3 occurrences; 40 km strike • Auriferousquartzveins in higher-orderstructures • Au-only + As, Ag, W, Sb, Bi • Ore mineralogy: Apy-Ccp-Py • Hydrothermal alteration mineralogy • Qtz-Ms-Chl-Ank • Sulfide-poor(< 5 vol.%); except BIF
The Paamiut gold province: structure • Metamorphic dates • 2850 – 2830 Ma: Paamiut orogeny • 2760 – 2740 Ma: Tasiusarsuaq orogeny
The Tartoq gold province: structure ±Au ±Au Au Au • Metamorphic dates • 2850 – 2830 Ma: Paamiut orogeny • 2760 – 2740 Ma: Tasiusarsuaq orogeny
Geologicalmap of southern West Greenland Sermilik prospect Bjørnesund occurrence Ca. 2840 Ma
Characteristics of gold mineralization Sermilik gold prospect • ≥ 2 locations; 4 km strike • Ca. 2740 Ma • Auriferousquartzveins in folds and shear zones • Gold-only + Ag, As • Ore mineralogy: Po-Ccp-Py-Ilm-Mag • Hydrothermal alteration mineralogy • Qtz-Grt-Bt-Kfs (660°C, 7.5-8 kbar) • Sulfide-poor(< 5 vol.%)
Tectonic model for the Sermilik prospect: Tasiusarsuaq orogeny N S
Characteristics of gold mineralization Godthåbsfjord gold province Tasiusarsuaq gold province ≥ 7 locations; terrane-scale Ca. 2675 Ma Quartzveins ± Au Ore mineralogy: Po-Ccp-Py-Ilm-Mag Hydrothermal alteration mineralogy Inner Qtz-Hbl ± Bt, Ep, Rt Proximal Qtz-Grt-Bt-Hbl± Ms(650°C, 3.5-4 kbar) Distal Bt ± Grt Sulfide-poor(< 5 vol.%) • ≥ 5 prospects; 110 km strike • 2985 Ma, 2715 Ma, 2630 Ma • Gold-quartz±carbonateveins • Ore mineralogy: Po-Ccp-Apy-Py-Ilm-Mag • Hydrothermal alteration mineralogy • Inner Qtz-Hbl ± Bt • Proximal Qtz-Grt-Bt-Hbl-Sil(530-630°C, 4-6 kbar) • Distal Bt ± Grt • Sulfide-poor(< 5 vol.%)
Structure of the Godthåbsfjord and Tasiusarsuaq gold provinces
Conclusions • Several stages of orogenic gold mineralization • ca. 2990 MaIsukasia orogeny • 2850 – 2830 Ma Paamiut orogeny • 2800 – 2740 Ma Tasiusarsuaq orogeny • 2720 – 2700 Ma Tre Brødre orogeny • 2670 – 2580 MaKapisilik orogeny • Hypozonal orogenic gold • Tasiusarsuaq gold province: single-stage – no potential • Godthåbsfjord gold province: multi-stage (?) – small deposits • Mesozonal orogenic gold • Paamiut gold province – not explored, good potential • Tartoq gold province – not explored, good potential