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Light rare earth elements (LREEs) are commonly enriched within iron oxide-copper-gold (IOCG) deposits within the Gawler Craton, South Australia. The LREEs are host within a number of phases including monazite, which is a resistate phase that can withstand processes of physical transport and weathering without significant chemical alteration. Recognition of this elevated LREE signature within rocks that have been transported away from mineralised zones can therefore be used as a geochemical vector towards potential IOCG mineralisation.In the northern Gawler Craton, South Australia, monazite occurs within basement rocks within and proximal to the Prominent Hill IOCG deposit. These basement rocks have been physically transported and dispersed during glacial activity subsequent to the mineralisation event, and redeposited in the cover sequence as a glacial diamictite. Here we show that the hydrothermal monazite within the mineralised zone has a characteristic geochemical signature, and that this signature has been preserved within monazite grains within the overlying glacial diamictite. The hydrothermal monazite is characteristically enriched in La and Ce, and depleted in Y and Th. A chemical criterion for exploration is derived. Monazite chemistry showing concentrations of La. +. Ce >. 63. wt.% and Y and Th . 75. ppm and Ce >. 155. ppm is considered anomalous. Data that also shows (La. +. Ce):Y ratios between 10:1 and 30:1 and (La. +. Ce):Th ratios between 16:1 and 32:1 is considered interesting. Ratios of (La. +. Ce):Y and (La. +. Ce):Th greater than 30:1 and 32:1 respectively are considered compelling. In the northern Gawler Craton, the scale of the footprint associated with the anomalous whole rock geochemical signature characteristic of Prominent Hill-style IOCG mineralisation is 2-3 times larger than the orebody itself. Dispersion of this signature is related to glacial processes and palaeotopography. This chemical criteria may potentially be used as a geochemical vectoring method towards Prominent Hill-style IOCG mineralisation, and may be applicable to exploration for other IOCG deposits within the Gawler Craton and further afield. Refereed/Peer-reviewed

Refereed/Peer-reviewed

We report a portable method for fluorescence-based detection of gold with detection limit as low as 74ppb. Using an optical fibre results in higher sensitivity for larger nanoparticles than cuvette measurements. Refereed/Peer-reviewed

The Ongole Domain in the southern Eastern Ghats Belt of India formed during the final stages of Columbia amalgamation at ca. 1600 Ma. Yet very little is known about the protolith ages, tectonic evolution or geographic affinity of the region. We present new detrital and igneous U–Pb–Hf zircon data and in-situ monazite data to further understand the tectonic evolution of this Columbia-forming orogen. Detrital zircon patterns from the metasedimentary rocks are dominated by major populations of Palaeoproterozoic grains (ca. 2460, 2320, 2260, 2200–2100, 2080–2010, 1980–1920, 1850 and 1750 Ma), andminor Archaean grains (ca. 2850, 2740, 2600 and 2550 Ma). Combined U–Pb ages and Lu–Hf zircon isotopic data suggest that the sedimentary protoliths were not sourced from the adjacent Dharwar Craton. Instead they were likely derived from East Antarctica, possibly the same source as parts of Proterozoic Australia. Magmatism occurred episodically between 1.64 and 1.57 Ga in the Ongole Domain, forming felsic orthopyroxene-bearing granitoids. Isotopically, the granitoids are evolved, producing εHf values between−2 and−12. The magmatism is interpreted to have been derived from the reworking of Archaean crust with only a minor juvenile input.Metamorphism between 1.68 and 1.60 Ga resulted in the partial to complete resetting of detrital zircon grains, as well as the growth of new metamorphic zircon at 1.67 and 1.63 Ga. In-situ monazite geochronology indicates metamorphism occurred between 1.68 and 1.59 Ga. The Ongole Domain is interpreted to represent part of an exotic terrane, which was transferred to proto-India in the late Palaeoproterozoic as part of a linear accretionary orogenic belt that may also have included south-west Baltica and south-eastern Laurentia. Given the isotopic, geological and geochemical similarities, the proposed exotic terrane is interpreted to be an extension of the Napier Complex, Antarctica, and may also have been connected to Proterozoic Australia (North Australian Craton and Gawler Craton). Refereed/Peer-reviewed

Tectonic models for the latest Paleoproterozoic to earliest Mesoproterozoic evolution of eastern Australia (circa 1620-1500 Ma) are diverse and either emphasize plume or plate margin activity, neither of which satisfactorily explains all geological observations. The dichotomy is largely attributed to geochemical, spatial and temporal data that suggest voluminous A-type felsic magmas are plume related, whereas distribution of arc-related magmas and intense orogenic overprint suggest plate margin activity. The salient geological events include arc-related magmatism at circa 1620-1610 Ma followed by a magmatic hiatus coincident with north-south crustal shortening (1610-1590 Ma) and a magmatic flare-up of A-type felsic magmas throughout the Gawler Craton (circa 1595-1575 Ma). These magmas form the oldest component of a northward younging hot spot track that extends to the Mount Isa Inlier. At circa 1590-1550 Ma, arc magmatism resumed along the northern margin of the Gawler Craton and the rest of eastern Australia records a 90 degrees shift in the regional shortening direction related to activity along the eastern margin of the Australian continent. A plume-modified orogenic setting satisfies all of the spatial and temporal relationships between magma generation and orogenic activity. In this model, the Gawler Craton and the adjacent subduction zone migrated over a mantle plume (circa 1620-1610 Ma). Resultant flat subduction caused transient orogenesis (1610-1595 Ma) in the overriding plate. Slab delamination and thermal assimilation of the plume and the subducting slab caused a switch to crustal extension in the overriding plate, resulting in extensive mantle-derived and crustal melting in the Gawler Craton (1595-1575 Ma). Refereed/Peer-reviewed

The origin of the submarine Naturaliste Plateau off the southwestern coast of Australia is controversial; previous work supports both oceanic and continental affinities for the basement to volcanic and sedimentary sequences. We report the first evidence of reworked Mesoproterozoic (ca. 1230-1190 Ma) continental crust, based on laser ablation-inductively coupled plasma-mass spectrometry analysis of zircons from granite and orthogneiss samples dredged from the southern margin of the plateau. Thermobarometry of peak metamorphic minerals and electron microprobe chemical dating of monazite reveal that these igneous rocks were metamorphosed to similar to 700 degrees C and similar to 6.5 kbar during the Cambrian Pinjarra Orogeny at ca. 515 Ma. These data confirm a continental origin for a significant swathe of the southern Naturaliste Plateau, and suggest that the protoliths may have affinities to Mesoproterozoic crust within the Albany-Fraser-Wilkes Orogen (Australia-Antarctica). The present Naturaliste Plateau basement beneath its volcanic carapace probably represents a middle- to lower-crustal extensional allochthon exhumed during Cretaceous hyperextensional breakup between Australia and Antarctica. Refereed/Peer-reviewed

Growing world demand for gold and decreasing discovery rates of ore deposits necessitates new techniques for gold exploration. Current techniques for the detection of ppb level of gold, such as inductively coupled plasma mass spectrometry (ICP-MS) are not field-deployable. By contrast, current portable device such as X-ray fluorescence (XRF) based sensors are not sufficiently sensitive. Thus, there is growing interest in developing a new, easy-to-use and fast method for detection of low concentrations of gold at the site of an exploration drilling rig. Two optical methods, absorption and fluorescence, are examined for their suitability for low gold concentration detection. Absorption study is based on the analysis of localised surface plasmon resonance peak. For fluorescence analysis, the ability of gold nanoparticles to specifically catalyse the conversion of the non-fluorescent compound (I-BODIPY) to the fluorescent derivative (H-BODIPY) is used. For both absorption and fluorescence methods, the limit of quantification (LOQ) of gold nanoparticles (NPs) was found to be dependent on the NP size (71 ppb of 5 nm and 24.5 ppb of 50 nm NPs for absorption and 74 ppb of 5 nm and 1200 ppb of 50 nm NPs for fluorescence). The LOQ for fluorescence for 50 nm NPs measured in a suspended core optical fibre was almost twice lower than in a cuvette. The field deployment potential of these methods was also determined using a portable set up. Refereed/Peer-reviewed