Wiemer, Daniel, Hagemann, Steffen G., Kemp, Anthony I.S., Hronsky, Jon, Martin, Laure, Ireland, Trevor, Thebaud, Nicholas, and Villanes, Carlos (2023) Superimposed orogeny as key to gold hotspot formation at the north Peruvian Gondwana margin. In: Proceedings of the 17th SGA Biennial Meeting (2) pp. 268-271. From: SGA 2023: 17th Biennial Meeting of the Society-for-Geology-Applied-to-Mineral Deposits (SGA) on Mineral Resources in a Changing World, 28 August - 1 September 2023, Zurich, Switzerland.

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Abstract

The geodynamic processes responsible for the formation of economic gold deposits remain controversial. It is postulated that the generation of gold-rich parental magma plays a crucial role. Two contrasting models prevail: i) selective uptake of gold as an incompatible element during low-degree partial melting of a crustal or upper mantle source, and ii) reactivation of a previously enriched source reservoir. We present bulk-geochemical and zircon U-Pb, Hf and O isotopic data from intrusive rocks that host the north Peruvian Carboniferous Pataz-Parcoy gold vein system to identify potential gold parental magmas and characterize their source. We find that hydrous, metal-enriched mafic rocks were emplaced episodically into the mid crust from similar to 370 Ma onwards. Zircon Hf isotopic data indicate that these magmas derived from an upper mantle domain that was likely pre-enriched during preceding Ordovician subduction. Sub-mantle delta O-18 zircon values imply the presence of remnant subducted oceanic crust, part of which is preserved as an ophiolite, within the upper mantle source. Furthermore, evidence of hydrothermally modified zircon attests to ore-fluid expulsion upon parental magma recharge concomitant with repeated amphibole break-down. The gold vein system formed after final magma emplacement and solidification at similar to 332 Ma, marking a tectonic switch towards back-arc magmatic activity.

Item ID:	83432
Item Type:	Conference Item (Research - E1)
ISBN:	9782839940450
Date Deposited:	30 Oct 2024 02:48
FoR Codes:	37 EARTH SCIENCES > 3703 Geochemistry > 370301 Exploration geochemistry @ 40% 37 EARTH SCIENCES > 3703 Geochemistry > 370303 Isotope geochemistry @ 30% 37 EARTH SCIENCES > 3705 Geology > 370502 Geochronology @ 30%
SEO Codes:	28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280107 Expanding knowledge in the earth sciences @ 100%
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