Caroline Tiddy

What does it take for a woman to thrive in an occupation that takes her to some of the most remote, rugged, and unforgiving locations on Earth? How do women geoscientists defy gendered barriers to succeed in an occupational context that requires both technical expertise and physical endurance? Using a social constructionist perspective, we examine the interplay of gendered barriers resulting from the physical and social context of such work, and women’s strategies to overcome them. We analyzed 67 semi-structured interviews with men and women geoscientists and, through the lens of context theorizing, uncovered a configuration of gendered barriers, both physical and social, the strategies employed by women to navigate those barriers, and the impact of organizational practices that perpetuate or address the gendered barriers. Women’s survival strategies to adapt to the context and organizational practices that supported adaptation often reinforced gendered barriers. Women’s change strategies and organizational practices that directly addressed the barriers were more effective.

Geochemical exploration criteria for relatively light rare earth element (LREE)-enriched iron oxide–copper–gold (IOCG) deposits have been tested and are applicable across multiple Proterozoic terranes in eastern Australia. The criteria were established using monazite from E1 (Cloncurry District, Queensland) and compared to existing data from Prominent Hill and Carrapateena (Gawler Craton, South Australia) and are effective in rare earth element (REE)-rich deposits. The criteria use La, Ce and Nd chemistry in combination with Th and Y, where La + Ce > 65 wt%, Nd < 12.5 wt%, and Y and Th are both <1 wt%. However, the criteria are not as effective in REE-poor deposits such as Osborne and SWAN (Cloncurry District). For these deposits, other trends in the monazite REEs, such as changing Y and Dy contents, are better to use, which can discriminate between mineralization-associated hydrothermal monazite that formed at low temperatures (low Y and Dy) from metamorphic monazite that formed at high temperatures and are not associated with mineralization (high Y and Dy). In metamorphosed terranes like the Cloncurry District, where metamorphism is well constrained, chemical and temperature information using monazite chemistry can give information on the formation conditions of monazite, potentially hinting at a nearby IOCG system.

Career perceptions factor into career-related decision-making. How women and men geoscientists perceive their careers can impact their career choices and therefore workforce gender composition. Analysis of visual metaphors provided during individual interviews and questionnaires of Australian women and men geoscientists show the following: Both genders find their careers challenging. Men acknowledged greater challenges in a woman's career, although women did not reciprocate this acknowledgment. Sense of achievement in geoscientists is low, especially among women. Women often do not feel included and gave metaphors of men with powerful, dominating, competitive narratives that do not match self-reflections from men. Within the context of social cognitive career theory, these career perceptions potentially highlight low career self-efficacy and outcome expectations within women geoscientists, which along with external factors can negatively impact retention. We propose strategies to cultivate supportive and inclusive communities to promote higher career self-efficacy and outcome expectations and therefore retain women geoscientists and achieve gender balance.

The stratiform and vein-hosted Kapunda Cu deposit in South Australia contains a saprolitized hydrothermal vein with 12.37 wt.% total rare earth oxide (TREO). The vein was analyzed by X-ray diffraction, scanning electron microscopy, synchrotron-based X-ray fluorescence microscopy and electron backscatter diffraction to understand the controls that govern high-grade REE accumulation during periods of intense weathering. Petrological assessments indicate the transformation of an apatite-calcite-aluminosilicate-bearing protolith to a supergene assemblage of Fe-oxides, kaolinite and REE-phosphate minerals that include rhabdophane-(Ce), monazite-(Ce) and florencite-(Ce). This transformation was facilitated by progressive acidification of the weathering fluid, which is indicated by: 1) the increasing crystallinity of authigenic Fe-oxides and kaolinite, which led to REE desorption; 2) the textural evolution and increase in grain size of authigenic REE-phosphates from nanoscopic crystallites, to acicular needles, to micro-scale hexagonal prisms; 3) the late dissolution of REE-phosphates; and 4) the replacement of goethite by jarosite, whose sulfate component originated from the oxidation and weathering of proximal sulfide minerals. Alongside the depletion of pH-buffering carbonate minerals that are indicated by the preservation of calcite menisci, this sulfide dissolution also facilitated acid generation. Results illustrate how highly acidic weathering fluids might facilitate either REE mobilization or REE accumulation in regolith. High-grade REE accumulation under acidic supergene conditions is prioritized when the host-rock contains a significant source of depositional ligands (i.e., phosphate in the form of apatite) that can be readily leached during intense weathering. Exploration companies should therefore assay routinely for REEs in any heavily weathered phosphatic rock, due to the observed efficiency of phosphate minerals as geochemical traps for REE accumulation.

STEM fields, including Geosciences, continue to be male-dominated. Unlike other STEM disciplines, the field of Geosciences has successfully improved gender balance in undergraduate degrees. Neverth...

Water-driven percussion drilling techniques, such as that used by the RoXplorer^® coiled tubing drill rig, return a rock sample as cuttings that are carried to the surface by the circulating drilling fluid. This drilling technique does not deliver a core sample. In order for the RoXplorer^® to be effective as a mineral-exploration drill rig, it is critical to develop robust, representative and repeatable sampling techniques for the rock cuttings and to establish with confidence the depth interval from which the sample was derived. The RoXplorer^® produces more than 7 kg/m of cuttings every few minutes (rate of penetration dependent) that are carried to the surface by the drilling fluid with a fluid return rate of 80–150 L/min. The cuttings, which range in size from ® drill rig in South Australia in February 2017. We drilled a vertical hole with RoXplorer^® starting 10 m to the northeast of an existing vertical diamond drill hole with well-characterised, shallow-dipping sedimentary and volcanic units. This allows comparison of drilling performance and sample quality against industry-standard drilling and sampling techniques. The performance of the splitter to take a representative continuous 1/8th subsample of drilling fluid and cuttings by volume was assessed based on its ability to resolve a 1 m interval of low-grade Cu mineralisation (0.74–1.03 wt% Cu) at 398 m that was detected in the reference diamond drill hole. The coiled tubing samples produced an equivalent and unbiased (chemistry and particle-size distribution) subsample, with sub-metre depth accuracy and comparable signal magnitude of the mineralisation at 398 m as detected in the diamond core.

Geochemical data are frequently collected from mineral exploration drill-hole samples to more accurately define and characterise the geological units intersected by the drill hole. However, large multi-element data sets are slow and challenging to interpret without using some form of automated analysis, such as mathematical, statistical or machine learning techniques. Automated analysis techniques also have the advantage in that they are repeatable and can provide consistent results, even for very large data sets. In this paper, an automated litho-geochemical interpretation workflow is demonstrated, which includes data exploration and data preparation using appropriate compositional data-analysis techniques. Multiscale analysis using a modified wavelet tessellation has been applied to the data to provide coherent geological domains. Unsupervised machine learning (clustering) has been used to provide a first-pass classification. The results are compared with the detailed geologist’s logs. The comparison shows how the integration of automated analysis of geochemical data can be used to enhance traditional geological logging and demonstrates the identification of new geological units from the automated litho-geochemical logging that were not apparent from visual logging but are geochemically distinct.

Detrital zircon grains preserved within clasts and the matrix of a basal diamictite sequence directly overlying the Carrapateena IOCG deposit in the Gawler Craton, South Australia are shown here to preserve U–Pb ages and geochemical signatures that can be related to underlying mineralisation. The zircon geochemical signature is characterised by elevated heavy rare-earth element fractionation values (Gd_N/Yb_N ≥ 0.15) and high Eu ratios (Eu/Eu* ≥ 0.6). This geochemical signature has previously been recognised within zircon derived from within the Carrapateena orebody and can be used to distinguish zircon associated with IOCG mineralisation from background zircon preserved within stratigraphically equivalent regionally unaltered and altered samples. The results demonstrate that zircon chemistry is preserved through processes of weathering, erosion, transport, and incorporation into cover sequence materials and, therefore, may be dispersed within the cover sequence, effectively increasing the geochemical footprint of the IOCG mineralisation. The zircon geochemical criteria have potential to be applied to whole-rock geochemical data for the cover sequence diamictite in the Carrapateena area; however, this requires understanding of the presence of minerals that may influence the HREE fractionation (Gd_N/Yb_N) and/or Eu/Eu* results (e.g., xenotime, feldspar).

The chemistry of hydrothermal monazite from the Carrapateena and Prominent Hill iron oxide-copper-gold (IOCG) deposits in the IOCG-rich Gawler Craton, South Australia, is used here to define geochemical criteria for IOCG exploration in the Gawler Craton as follows: Monazite associated with IOCG mineralisation: La + Ce > 63 wt% (where La > 22.5 wt% and Ce > 37 wt%), Y and/or Th < 1 wt% and Nd < 12.5 wt%; Intermediate composition monazite (between background and ore-related compositions): 45 wt% < La + Ce < 63 wt%, Y and/or Th < 1 wt%. Intermediate monazite compositions preserving Nd > 12.5 wt% are considered indicative of Carrapateena-style mineralisation; Background compositions: La + Ce < 45 wt% or Y or Th > 1 wt%. Mineralisation-related monazite compositions are recognised within monazite hosted within cover sequence materials that directly overly IOCG mineralisation at Carrapateena. Similar observations have been made at Prominent Hill. Recognition of these signatures within cover sequence materials demonstrates that the geochemical signatures can survive processes of weathering, erosion, transport and redeposition into younger cover sequence materials that overlie older, mineralised basement rocks. The monazite geochemical signatures therefore have the potential to be dispersed within the cover sequence, effectively increasing the geochemical footprint of mineralisation.