Proxies for Basement Structure and Its Implications for Mesoproterozoic Metallogenic Provinces in the Gawler Craton

Abstract

The link between mineral resources and crustal‐rooted structures has been proposed for many of the world's most significant mineral provinces. Here we utilize a new approach by interpreting potential field data, including satellite gravity data, and high‐resolution continental‐scale magnetotelluric data, constrained with aeromagnetic, and seismic tomography and reflection data, to determine the distribution of crustal‐scale faults in the Archean to Proterozoic Gawler Craton (South Australia). The eastern flank of the craton hosts the supergiant Olympic Dam iron oxide‐copper‐gold (IOCG) deposit within a larger Olympic IOCG province. The central part of the craton contains gold‐only deposits, which define the Central Gawler Gold province. Both of these provinces are part of a Mesoproterozoic mineral system with an extensive hydrothermal alteration footprint, which formed during complicated tectonic mode switches. We show that both types of mineralization are located in proximity to crustal‐scale structures that appear to connect deep crustal fragments, which likely record the amalgamation of the Archean nucleus of the craton during the Neoarchean with subsequent reworking during the Mesoproterozoic. Many of these structures do not have a surface expression but coincide with gradients in magnetism, gravity, and electric resistivity anomalies, the latter data set suggesting they acted as fluid pathways extending to the lower crust. The results indicate that the first‐order controls on the distribution of IOCG and Central Gawler Gold metallogenic provinces are inherited from earlier tectonic events, which formed major crustal boundaries and related structures that are prone to reworking during later tectonism.

The Olympic Cu-Au Province, Gawler Craton: A Review of the Lithospheric Architecture, Geodynamic Setting, Alteration Systems, Cover Successions and Prospectivity

“…The Gawler Craton IOCG deposits appear to be linked to a major crustal and indeed lithospheric scale boundary. This boundary lies along a north-west trend and its presence is confirmed by changes in mantle and lower crustal conductivity, gradients in seismic wave speed, variations in satellite gravity and isotopic data from magmatic rocks (e.g., [32,[95][96][97]). Lithospheric scale boundaries are critical elements of mineral systems as they are typically weaker and reactivate during strain, thereby providing fluid and mass conduits that connect the mantle to the crust (e.g., [98,99]).…”

The Bayankhongor Metal Belt (Mongolia): Constraints on Crustal Architecture and Implications for Mineral Emplacement from 3-D Electrical Resistivity Models

“…Thus the crustal features imaged with geophysical models, such as the resistivity models in this contribution, can give insights into the emplacement of mineral systems. Other geophysical data (such as magnetism and gravity), and their gradients, can also highlight crustal boundaries [21].…”

Resolving tectonic settings of ancient magmatic suites using structural, geochemical and isotopic constraints: the example of the St Peter Suite, southern Australia

“…Magnetotelluric data suggest the St Peter Suite lies above a very resistive lower crust and continental mantle (Thiel & Heinson, 2010, 2013. By correlation with the geophysical properties of the Neoarchean rocks in the Gawler Craton, the St Peter Suite is inferred to overlie Archean lower crust (Motta et al, 2019;Thiel & Heinson, 2013).…”