Mantle-derived fluid flux controls Olympic Dam-style Fe oxide-Cu-Au mineralisation

TL;DR

This study shows how mantle-derived fluids influence the formation of large iron oxide-copper-gold mineral deposits in the crust.

Contribution

It demonstrates a lithosphere-wide plumbing system connecting the mantle to IOCG deposits using 3D resistivity modeling.

Findings

A 3D resistivity model links enriched mantle beneath the Gawler Craton to the Olympic Dam IOCG deposit.

The lithosphere's architecture and crustal conditions are critical for forming large IOCG deposits.

Mantle-derived fluid flux provides a low-entropy environment for mineral deposition.

Abstract

Conventional mineral exploration has focused on processes in the mid-upper crust, however recent advances in the geophysical and geochemical understanding of the sub-continental lithospheric mantle (SCLM) suggest that the macroscopic architecture of the lithosphere plays a key role in the localization of giant mineral deposits. Here, we use AusLAMP (Australian Lithospheric Architecture Magnetotelluric Project) magnetotelluric (MT) data to image the footprint of an entire mineral system, the Mesoproterozoic iron oxide copper-gold (IOCG) province of the eastern Gawler Craton, Southern Australia. Our new 3D resistivity model demonstrates a physical connection exists between the anomalous, enriched SCLM beneath the Gawler Craton and the detailed resistivity mapping of the upper and middle crust beneath the Olympic Dam IOCG deposit. This conductivity network represents a whole of lithosphere plumbing system, which constitutes a direct pathway from a mantle source at the margins of an Archean cratonic core to form the metallogenic province at the surface. We argue that primary controls of lithospheric architecture and optimal crustal conditions, including high strain localization and secondary fluid availability, are required for large scale thermal events to provide the necessary low-entropy physico-chemical environment for deposition of large IOCG type deposits in the crust.

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