Saintilan, N. J., Selby, D., Hughes, J., Schlatter, D. M., Kolb, J. and Boyce, A. (2019) A Refined View of the 'Mesoarchaean gold event'. In: 15th SGA Biennial Meeting on Life with Ore Deposits on Earth, Glasgow, Scotland, 27-30 Aug 2019, pp. 715-718. ISBN 9780852619636
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Publisher's URL: https://www.sga2019glasgow.com/abstract
Abstract
The controversial 'Mesoarchaean gold event' might have added the bulk of all gold to the juvenile continental crust at the onset of crust generation by plate tectonic processes at ca. 3.0 billion years (Ga). Here, we connect the 'Mesoarchaean gold event' to the precipitation of ca. <3.19-2.98 Ga seafloor massive arsenopyrite accompanying ca. <3.19-3.01 Ga basalt magmatism. Hydrothermal alteration mobilized As, Re, Os and Au from serpentinites of lower crustal harzburgite cumulates to yield arsenopyrite with invisible gold. In major shear zones, retrograde greenschist-facies metamorphism caused local dissolution of arsenopyrite, reset its Re-Os geochronometer, and liberated gold which was deposited as native gold with pyrite at 2.66 Ga. The initial Os isotope ratios of Neoarchaean arsenopyrite (Os-187/Os-188(i); = 0.13 +/- 0.02) and gold-bearing pyrite (0.12 +/- 0.02) overlap with an estimated Os-187/Os-188 ratio for the Mesoarchaean mantle (0.11 +/- 0.01, calculated by using the present-day values of Re-187/Os-188 = 0.435 +/- 0.055 and Os-187/Os-188 = 0.130 +/- 0.001 for a primitive upper mantle; Meisel et al. 2001; Carlson et al. 2005) and preclude contribution of radiogenic crustal Os. This ca. 2.66 Ga lode gold mineralization may bear testament to the endowment of Earth's stabilizing continental crust through metamorphic upgrading of bulk gold originally extracted from the Mesoarchaean mantle.
| Item Type: | Conference Proceedings |
|---|---|
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Boyce, Professor Adrian |
| Authors: | Saintilan, N. J., Selby, D., Hughes, J., Schlatter, D. M., Kolb, J., and Boyce, A. |
| College/School: | College of Science and Engineering > Scottish Universities Environmental Research Centre |
| ISBN: | 9780852619636 |
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