Heterogeneity of the sub-continental lithospheric mantle and ‘non-juvenile’ mantle additions to a Proterozoic silicic large igneous province

Wade, Claire E.; Payne, Justin L.; Barovich, Karin M.; Reid, Anthony

doi:10.1016/j.lithos.2019.05.005

Cited by 24 publications

(14 citation statements)

References 61 publications

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“…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]).…”

Section: Lithospheric Architecture Of the Olympic Cu-au Provincementioning

confidence: 76%

“…The association between extensive bimodal A-type magmatism, high-temperature metamorphism, and localized compressional deformation, is suggestive of an intracontinental setting for this time period in the Gawler Craton and Curnamona Province [70]. Indeed, many models for the geodynamics of these events emphasize mantle underplating or mantle plume activity as a key mechanism [52,54,96,102]. In these models, a mantle plume underplate the base of the lithosphere causing intrusion of mafic magmas into the lower crust resulting in extensive crustal melting.…”

Section: Geodynamic Setting Of the Olympic Cu-au Provincementioning

confidence: 99%

“…Metasomatized subcontinental lithospheric mantle beneath the Gawler Craton in general, and the eastern Gawler Craton in particular [26,32,96]; • High-temperature igneous intrusion as manifest by the Hiltaba Suite and related bimodal Gawler Range Volcanics and Benagerie Volcanic Suite [53,70,107,108]; • Synchronous deformation activity that was largely focused along the margins of the Gawler Craton and Curnamona Province in regions such as Yorke Peninsula [56], northern Gawler Craton [55,109] and the southern Curnamona Province such as around the Broken Hill district (e.g., [71,72,110]); •…”

mentioning

confidence: 99%

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

Reid

2019

Minerals

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The Olympic Cu-Au Province is a metallogenic province in South Australia that contains one of the world's most significant Cu-Au-U resources in the Olympic Dam deposit. The Olympic Cu-Au Province also hosts a range of other iron oxide-copper-gold (IOCG) deposits including Prominent Hill and Carrapateena. This paper reviews the geology of the Olympic Cu-Au Province by investigating the lithospheric architecture, geodynamic setting and alteration systematics. In addition, since the province is almost entirely buried by post-mineral cover, the sedimentary cover sequences are also reviewed. The Olympic Cu-Au Province formed during the early Mesoproterozoic, ca. 1.6 Ga and is co-located with a fundamental lithospheric boundary in the eastern Gawler Craton. This metallogenic event was driven in part by melting of a fertile, metasomatized sub-continental lithospheric mantle during a major regional tectonothermal event. Fluid evolution and multiple fluid mixing resulted in alteration assemblages that range from albite, magnetite and other higher temperature minerals to lower temperature assemblages such as hematite, sericite and chlorite. IOCG mineralisation is associated with both high and low temperature assemblages, however, hematite-rich IOCGs are the most economically significant. Burial by Mesoproterzoic and Neoproterozoic-Cambrian sedimentary successions preserved the Olympic Cu-Au Province from erosion, while also providing a challenge for mineral exploration in the region. Mineral potential modelling identifies regions within the Olympic Cu-Au Province and adjacent Curnamona Province that have high prospects for future IOCG discoveries. Exploration success will rely on improvements in existing potential field and geochemical data, and be bolstered by new 3D magnetotelluric surveys. However, drilling remains the final method for discovery of new mineral resources.

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Section: Lithospheric Architecture Of the Olympic Cu-au Provincementioning

confidence: 76%

Section: Geodynamic Setting Of the Olympic Cu-au Provincementioning

confidence: 99%

mentioning

confidence: 99%

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

Reid

2019

Minerals

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“…Whole-rock major-and trace-element geochemistry was undertaken at a commercial laboratory, ALS Global, Perth (http://www.alsglobal.com/minerals.aspx). The Sm-Nd-Sr isotopic composition of whole-rock samples was determined at the University of Adelaide using methods similar to those reported by Wade, Hand, and Barovich (2005) and Wade, Payne, Barovich and Reid (2019).…”

Section: Methodsmentioning

confidence: 99%

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

Reid

Pawley

Wade

et al. 2019

Australian Journal of Earth Sciences

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Reconstructing ancient tectonic environments is inherently difficult and requires the integration of many datasets. Here we attempt to reconstruct the tectonic setting of a Proterozoic magmatic rock suite from the Archean to Mesoproterozoic Gawler Craton, South Australia. We evaluate previous models of subduction or non-subduction tectonics for the St Peter Suite through field observations coupled with geochemical and isotopic data. Field observations indicate the presence of mafic magma chambers, felsic plutons and zones of mixing represented by multiphase plutons and zones of magma transfer. Syn-magmatic and solid-state deformation fabrics suggest magmatism was associated with a compressional tectonic regime, at least during some stages of magmatism. Zircon U-Pb geochronology suggests magmatism occurred between ca 1633 and ca 1608 Ma, an interval of ca 25 Myr. Mafic rocks are tholeiitic and enrichment in high field strength and light rare earth elements supports a modified mantle source region. Mafic rocks have eNd 1620 Ma values around 0, and zircon eHf (t) values around 4, supporting minor crustal contamination. Felsic plutons have a geochemical signature similar to average continental crust, eNd 1620 Ma between -3.7 and 0.4, and zircon Lu-Hf isotopic compositions that yield to eHf (t) values between -1.8 and 7.7, suggesting they were derived from fractionation of enriched tholeiitic parent magmas. A model for the formation of the St Peter Suite that is most consistent with the available data is one that places the magmatism in a broadly continental magmatic arc setting, albeit one in which little or no Archean crust was involved. Potentially this magmatic arc could have been built on a thinned, or hyper-extended continental margin. The integration of structural, geochemical and isotopic constraints has provided a more holistic view of the St Peter Suite petrogenesis than previously available. HIGHLIGHTSEvaluation of models of subduction vs non-subduction tectonics for formation of Paleoproterozoic magmatic suite Evidence for syn-magmatic compression and mafic-felsic magma mingling Isotopically juvenile (Nd-Sr-Hf) with mantle-like zircon d 18 O values Continental arc setting proposed, possibly on hyper-extended continental margin ARTICLE HISTORY

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“…Formation of IOCG deposits remains highly contested, particularly with respect to sources and timing of fluids and contained metals (References [1,2], and references therein). In the Gawler Craton, Minerals 2019, 9,364 5 of 34 lithospheric architecture, mantle metasomatism, and cratonic metallogeny [37,38] have been linked to generic models for IOCG genesis with global applicability [1]. The large volumes of Fe required to form IOCG deposits associated with granitoid-derived fluids or felsic magmatism have recently been proposed to be derived from underplating mafic magma in deeper reservoirs allowing for volatile-and metal-transfer via magma mingling and magnetite flotation [39].…”

Section: Zircon Chemistry and Structurementioning

confidence: 99%

Zircon at the Nanoscale Records Metasomatic Processes Leading to Large Magmatic–Hydrothermal Ore Systems

et al. 2019

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The petrography and geochemistry of zircon offers an exciting opportunity to better understand the genesis of, as well as identify pathfinders for, large magmatic-hydrothermal ore systems. Electron probe microanalysis, laser ablation inductively coupled plasma mass spectrometry, high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging, and energy-dispersive X-ray spectrometry STEM mapping/spot analysis were combined to characterize Proterozoic granitic zircon in the eastern Gawler Craton, South Australia. Granites from the~1.85 Ga Donington Suite and~1.6 Ga Hiltaba Suite were selected from locations that are either mineralized or not, with the same style of iron-oxide copper gold (IOCG) mineralization. Although Donington Suite granites are host to mineralization in several prospects, only Hiltaba Suite granites are considered "fertile" in that their emplacement at~1.6 Ga is associated with generation of one of the best metal-endowed IOCG provinces on Earth. Crystal oscillatory zoning with respect to non-formula elements, notably Fe and Cl, are textural and chemical features preserved in zircon, with no evidence for U or Pb accumulation relating to amorphization effects. Bands with Fe and Ca show mottling with respect to chloro-hydroxy-zircon nanoprecipitates. Lattice defects occur along fractures crosscutting such nanoprecipitates indicating fluid infiltration post-mottling. Lattice stretching and screw dislocations leading to expansion of the zircon structure are the only nanoscale structures attributable to self-induced irradiation damage. These features increase in abundance in zircons from granites hosting IOCG mineralization, including from the world-class Olympic Dam Cu-U-Au-Ag deposit. The nano-to micron-scale features documented reflect interaction between magmatic zircon and corrosive Fe-Cl-bearing fluids in an initial metasomatic event that follows magmatic crystallization and immediately precedes deposition of IOCG mineralization. Quantification of α-decay damage that could relate zircon alteration to the first percolation point in zircon gives~100 Ma, a time interval that cannot be reconciled with the 2-4 Ma period between magmatic crystallization and onset of hydrothermal fluid flow. Crystal oscillatory zoning and nanoprecipitate mottling in zircon intensify with proximity to mineralization and represent a potential pathfinder to locate fertile granites associated with Cu-Au mineralization.Minerals 2019, 9, 364 3 of 34 followed by partial to complete recrystallization. The amorphous domains begin to interconnect due to the radiation damage (α-decay), over a time period determined by U/Th concentrations and annealing rates [16]. The time dependency of structural damage is highly relevant for geochronology, as it can result in discordance of the U-Pb system, most commonly through Pb-loss. Disturbances to zircon U-Pb systematics via metamictization can, however, be selectively eliminated by chemical abrasion of damaged zones, prior to ID-TIMS, permitting high-precisio...

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Heterogeneity of the sub-continental lithospheric mantle and ‘non-juvenile’ mantle additions to a Proterozoic silicic large igneous province

Cited by 24 publications

References 61 publications

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

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

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

Zircon at the Nanoscale Records Metasomatic Processes Leading to Large Magmatic–Hydrothermal Ore Systems

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