Using U-Pb, Lu-Hf and O Isotopes in Zircons to Unlock the Crust-Mantle Evolution and Relationships to Mineral Systems of the Marmion Terrane (3.02-2.68 Ga), Superior Province, Canada

French Title: Apport des données U-Pb, Lu-Hf et Isotopes de l’Oxygene dans la Compréhension de l‘Évolution Croute-Manteau et de son Influence sur la Metallogénie du Marmion Terrane (3.02-2.68 Ga), Province du Supérieur, Canada

Katarina Edith Bjorkman1,2, T. Campbell McCuaig1,2, Yongjun Lu1,2 and Pete N Hollings3, (1)University of Western Australia, Crawley, WA, Australia, (2)ARC Centre of Excellence for Core to Crust Fluid Systems, Centre for Exploration Targeting, Perth, Australia, (3)Lakehead University, Thunder Bay, ON, Canada

Contact First Author: Katarina Edith Bjorkman; katarina.bjorkman@research.uwa.edu.au

Previously Published Material: Only some preliminary U-Pb results by SHRIMP were reported in an article to the OGS Summary of Field Work and Other Activities and within a poster at the Centre for Exploration Targeting Members' Day.Bjorkman, K.E., McCuaig, T.C., Lu, Y.J., Beakhouse, G.P., Hollings, P. and Smyk, M.C. 2014. The Marmion terrane four-dimensional crust–mantle evolution and mineral systems: An update; in Summary of Field Work and Other Activities 2014, Ontario Geological Survey, Open File Report 6300, p.12-1 to 12-13.Bjorkman, K.E., McCuaig, T.C., Lu, Y.J., Hollings, P. Fiorentini, M.L., Kemp, A.I.S (2014) The 4D crust-mantle evolution and mineral system distribution of the 3.0 Ga Marmion Terrane, Western Superior Craton, Canada; in CET Corporate Members’’ Day 2014, University of Western Australia, Crawley, 6009, WA, Australia

Abstract ID#: 34078

 

English Abstract:
The architecture of the lithosphere focuses the transfer of fluid, mass and energy from the Earth’s mantle to crust, thereby controlling the location of many major mineral systems. Modeling the crust-mantle evolution through time and space can therefore provide mappable exploration criteria for mineralization. Isotopes of Hf and O provide insight into rates, processes and setting of crust-mantle growth and can serve as “paleogeophysics” to image the 4D lithospheric architecture. We use isotopes of U-Pb, Lu-Hf and O in zircons to identify major lithospheric blocks of the Marmion Terrane (3.02-2.68 Ga), Wabigoon Subprovince, Superior Craton. This provides insight into crustal growth rates and processes across the Meso to Neoarchean transition.

Other multi-isotopic mapping of Archean cratons has typically been craton-wide, and because of the scale have large sample spacing. This study focuses on a geologically complex, yet well-characterized terrane to give detailed context to the results of larger studies. Nine lithotectonic domains over 300 myr are preserved in crustal and supracrustal events in the south-central Wabigoon Subprovince. U-Pb geochronology by SHRIMP confirms magmatic age domains at 2.99-3.02, 2.93-2.94, 2.89, 2.82-2.83, 2.78-2.80, 2.70-2.73, and 2.67-2.68 Ga. Large portions of postulated terrane boundaries within the study area are obscured by post-tectonic granitoid batholiths and are not observable in geophysics or geology. Au, Ni-S, Cu-Zn and Fe mineralization are localized in Meso-Neoarchean greenstone belts and proximal TTG batholiths of the terrane.

We present multi-isotopic, geochemical and petrographic results of granitoid rocks across the Marmion terrane. The results map the internal and external boundaries of the Marmion Terrane, showing that crustal growth across the Marmion terrane largely occurred by progressive magmatic addition and reworking of older crust.

Back to: Canadian Cratons Through Time: 4.0 Ga of Chemical Evolution and Tectonism