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Societal Impact Statement Cereal crops such as wheat and barley provide key nutritional elements to the human diet. However, the distribution of nutrients within the cereal grain itself is critically important, as nutrients can be lost during the grain milling process. Mycorrhizal fungi can take up nutrients from the soil and deliver them to plants, and consequently, grain nutrient content can be modified by inoculation of the soil with mycorrhizal fungi. Here we show at the microscopic level how mycorrhizal fungi modify the concentration and distribution of nutrients within wheat and barley grain, and consider the impact of this for human nutrition. Summary The concentration and distribution of nutrients in cereal grains are critically important for human nutrition. Mycorrhizal fungi affect the yield and nutrition of cereal crops, but there has been little focus on the effects on the grain, particularly at the microscopic level. Although arbuscular mycorrhizal fungi (AMF) can modify grain nutrient concentrations relative to mock‐inoculated plants, it is not known whether this contributes to modifications to the distribution of nutrients within the grain. Barley and bread wheat plants were grown to maturity with or without AMF (Rhizophagus irregularis) inoculation in soil amended with 20 mg added zinc kg−1. The resulting grain from matured plants was dried, fixed and sectioned to the root primordia level, then subjected to laser ablation ICP‐MS to analyse the distribution and concentration of 12 elements. Elemental concentration and localisation in the grain samples was highly influenced by plant species, and for some elements, AMF inoculation. Heavy metals (zinc, iron, manganese, copper, cobalt and nickel) were the most highly influenced by AMF inoculation, particularly in wheat; macronutrients including phosphorus, magnesium, potassium and sulphur were also affected by AMF, particularly in barley. Elemental concentrations, particularly of macronutrients, tended to be greater in mycorrhizal barley grain than non‐mycorrhizal, but the reverse was observed in wheat grain. Mycorrhizal plants of both species had reduced accumulation of manganese, nickel and cobalt in the grain. Cereal crops such as wheat and barley provide key nutritional elements to the human diet. However, the distribution of nutrients within the cereal grain itself is critically important, as nutrients can be lost during the grain milling process. Mycorrhizal fungi can take up nutrients from the soil and deliver them to plants, and consequently, grain nutrient content can be modified by inoculation of the soil with mycorrhizal fungi. Here we show at the microscopic level how mycorrhizal fungi modify the concentration and distribution of nutrients within wheat and barley grain, and consider the impact of this for human nutrition.

Continental rifts have a significant role in supercontinent breakup and the development of sedimentary basins. The Australian Adelaide Superbasin is one of the largest and best-preserved rift systems that initiated during the breakup of Rodinia, yet substantial challenges still hinder our understanding of its early evolution and place within the Rodinian supercontinent. In the past decade, our understanding of rift and passive margin development, mantle plumes and their role in tectonics, geodynamics of supercontinent breakup, and sequence stratigraphy in tectonic settings has advanced significantly. However, literature on the early evolution of the Adelaide Superbasin has not been updated to reflect these advancements. Using new detrital zircon age data for provenance, combined with existing literature, we examine the earliest tectonic evolution of the Adelaide Superbasin in the context of our modern understanding of rift system development. A new maximum depositional age of 893 ± 9 Ma from the lowermost stratigraphic unit provides a revised limit on the initiation of sedimentation and rifting within the basin. Our model suggests that the basin evolved through an initial pulse of extension exploiting pre-existing crustal weakness to form half-grabens. Tectonic quiescence and stable subsidence followed, with deposition of a sourceward-shifting facies tract. Emplacement and extrusion of the Willouran Large Igneous Province occurred at c. 830 Ma, initiating a new phase of rifting. This rift renewal led to widespread extension and subsidence with the deposition of the Curdimurka Subgroup, which constitutes the main cyclic rift sequence in the Adelaide Superbasin. Our model suggests that the Adelaide Superbasin formed through rift propagation to an apparent triple junction, rather than apical extension outward from this point. In addition, we provide evidence suggesting a late Mesoproterozoic zircon source to the east of the basin, and show that the lowermost stratigraphy of the Centralian Superbasin, which is thought to be deposited coevally, had different primary detrital sources.

Production of radionuclide-free copper concentrates is dependent on understanding and controlling the deportment of daughter radionuclides (RNs) produced from 238U decay, specifically 226Ra, 210Pb, and 210Po. Sulfuric acid leaching is currently employed in the Olympic Dam processing plant (South Australia) to remove U and fluorine from copper concentrates prior to smelting but does not adequately remove the aforementioned RN. Due to chemical similarities between lead and alkaline earth metals (including Ra), two sets of experiments were designed to understand solution interactions between Sr, Ba, and Pb at various conditions. Nanoscale secondary ion mass spectrometry (NanoSIMS) isotopic spatial distribution maps and laser ablation inductively coupled-plasma mass spectrometry transects were performed on laboratory-grown crystals of baryte, celestite, and anglesite which had been exposed to different solutions under different pH and reaction time conditions. Analysis of experimental products reveals three uptake mechanisms: overgrowth of nearly pure SrSO4 and PbSO4 on baryte; incorporation of minor of Pb and Ba into celestite due to diffusion; and extensive replacement of Pb by Sr (and less extensive replacement of Pb by Ba) in anglesite via coupled dissolution-reprecipitation reactions. The presence of H2SO4 either enhanced or inhibited these reactions. Kinetic modelling supports the experimental results, showing potential for extrapolating the (Sr, Ba, Pb)SO4 system to encompass RaSO4. Direct observation of grain-scale element distributions by nanoSIMS aids understanding of the controlling conditions and mechanisms of replacement that may be critical steps for Pb and Ra removal from concentrates by allowing construction of a cationic replacement scenario targeting Pb or Ra, or ideally all insoluble sulfates. Experimental results provide a foundation for further investigation of RN uptake during minerals processing, especially during acid leaching. The new evidence enhances understanding of micro- to nanoscale chemical interactions and not only aids determination of where radionuclides reside during each processing stage but also guides development of flowsheets targeting their removal.

Alcohol misuse is often a chronic problem such that relapses following treatment are common. One potential protective factor for alcohol misuse is self-compassion, which includes self-kindness, feelings of common humanity, and mindfulness when faced with personal suffering and hardships. This study tested the hypothesis that self-compassion, and specifically self-compassion promoting facets including self-kindness, common humanity, and mindfulness, were longitudinally associated with reduced alcohol use among a sample of men and women in substance use disorder treatment (N = 62). Results partially supported the hypothesis, in that only the mindfulness facet of self-compassion was associated with decreased alcohol use over time. Sex and age differences as they related to the positive facets of self-compassion and alcohol use emerged. These findings suggest that positive facets of self-compassion may be beneficial factors to cultivate in alcohol treatment programs.

In situ rubidium–strontium (Rb–Sr) geochronology, using laser ablation–inductively coupled plasma–tandem mass spectrometry (LA-ICP-MS/MS) technology, allows rapid dating of K-rich minerals such as micas (e.g. biotite, muscovite, and phlogopite) and K-feldspar (potassium-containing feldspar). While many studies have demonstrated the ability of the method, analytical protocols vary significantly, and to date, no studies have provided an in-depth comparison and synthesis in terms of precision and accuracy. Here we compare four calibration protocols based on commonly used reference materials (RMs) for Rb–Sr dating. We demonstrate that downhole fractionation trends (DHFs) for natural biotite, K-feldspar, and phlogopite contrast with that for the commonly used Mica-Mg nano powder reference material. Consequently, Rb–Sr dates calibrated to Mica-Mg can be up to 5 % inaccurate, and the degree of inaccuracy appears to be unsystematic between analytical sessions. Calibrating to Mica-Mg also introduces excess uncertainty that can be avoided with a more consistent primary calibration material. We propose a calibration approach involving (1) NIST-610 glass as the primary reference material (PRM) for normalisation and drift correction and (2) a natural mineral with similar DHF characteristics to the analysed samples as matrix correction RM (MCRM) to correct the Rb/Sr ratio for matrix-induced offsets. In this work, MDC phlogopite (the source mineral for Mica-Mg nano powder) was used as the MCRM, consistently producing accurate Rb–Sr dates for a series of natural biotites and K-feldspars with well-characterised expected ages. Biotite from the Banalasta Adamellite, Taratap Granodiorite, and Entire Creek pegmatite are also suitable RMs for Rb/Sr ratio calibration purposes, with consistently <1.5 % fully propagated uncertainties in our methodological approach. Until calibration using isochronous natural standards as the primary RM becomes possible in data reduction software, the two-step calibration approach described here is recommended.

Compositional data, comprising electron probe microanalysis and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) trace-element data, are presented for common (Cu)-Pb-Sb sulfosalts (bournonite, jamesonite, tetrahedrite, and boulangerite), subordinate semseyite, heteromorphite, robinsonite, and (Cu)-Pb-Bi-Sb sulfosalts, as well as for accompanying base metal sulfides (BMS) in auriferous gold veins from the Gutaishan Au-Sb deposit, southern China. The objectives of the study were to identify whether these sulfosalts represent overlooked hosts for precious metals and other trace elements of petrogenetic or economic interest, establish partitioning trends among coexisting sulfosalt species and between sulfosalts and BMS, and to seek evidence for a genetic link between the abundance of (Cu)-Pb-Sb sulfosalts and the high-fineness of native gold in the deposit. All (Cu)-Pb-Sb sulfosalts analyzed were found to be remarkably poor hosts for gold and thus do not contribute to the overall mineralogical balance for gold. Trace yet measurable concentrations of Au are, however, noted in the (Cu)-Pb-Bi-Sb sulfosalts, in agreement with published data indicating that (Cu)-Pb-Bi-Sb sulfosalts may be minor Au-hosts in some ore systems. Silver is preferentially partitioned into tetrahedrite at the expense of other sulfosalt phases, and tetrahedrite is thus the major host for Ag in the Gutaishan deposit. LA-ICP-MS trace element mapping allows partitioning relationships among different sulfosalt and BMS phases to be determined for several trace elements. Jamesonite concentrates Fe, Zn, Bi, Cd, Ag, Ni, and In over coexisting bournonite, yet boulangerite is the better host for As, Ag, Sn, Se, and Te than jamesonite. Cd and Co are typically enriched in sphalerite relative to any sulfosalt, and when present, pyrite is always enriched in Au and Co relative to all other phases. A high Au/Ag ratio in the ore-forming fluid, the presence of abundant tetrahedrite that has sequestered silver during mineral precipitation, and a lack of evidence for cooling-driven precipitation may be significant reasons for the formation of high-fineness gold throughout the deposit. Two generations of native gold are documented whereby the first is coarse-grained, Ag- and Bi-bearing, and is associated with the main (Cu)-Pb-Sb sulfosalts (bournonite, jamesonite, tetrahedrite, and boulangerite). The second generation is fine-grained and has the highest fineness. Increase in the complexity of sulfosalt assemblages, re-distribution of Ag within coarse native gold and dissolution-reprecipitation reactions among the sulfosalt-gold association increase the gold fineness. The present study shows that linking petrographic aspects at the micrometer-scale with minor/trace element distributions in complex sulfidesulfosalt assemblages can track a complex history of Au deposition and enrichment.

The Mount Weld rare earth element (REE) deposit, Western Australia, is one of the largest of its type on Earth. Current mining exploits the high-grade weathered goethite-bearing resource that lies above, and which represents the weathering product of a subjacent carbonatite. The mineralogy, petrography, deportment of lanthanides among the different components, and variation in mineral speciation, textures, and chemistry are examined. Microanalysis, involving scanning electron microscope (SEM) imaging, electron probe microanalysis (EPMA) and laser ablation inductively coupled-plasma mass spectrometry (LA-ICP-MS), was conducted on sized fractions of three crushed and ground laterite ore samples from current and planned production, and a representative sample from the underlying carbonatite. High-magnification imaging of particles in laterite samples show that individual REE-bearing phases are fine-grained and extend in size well below the micron-scale. Nanoscale inclusions of REE-phosphates are observed in apatite, Fe-(Mn)-(hydr)oxides, and quartz, among others. These have the appearance, particularly in fluorapatite, of pervasive, ultrafine dusty domains. Apart from the discrete REE minerals and abundant nano- to micron-scale inclusions in gangue, all ore components analysed by LA-ICP-MS contain trace to minor levels of REEs within their structures. This includes apatite, where low levels of REE are confirmed in preserved igneous apatite, but also Fe- and Mn-(hydr)oxides in which concentrations of hundreds, even thousands of ppm are measured. This is significant given that Fe-(Mn)-(hydr)oxides are the most abundant component of the laterite and points to extensive mobility and redistribution of REEs, and especially HREE, during progressive lateritisation. Late-formed minerals, notably tiny grains of cerianite, reflect a shift to oxidising conditions. REE-fluorocarbonates are the main host for REEs in carbonatite and are systematically replaced by hydrated, Ca-bearing REE-phosphates (largely rhabdophane). The latter displays varied compositions but is characteristically enriched in HREE relative to monazite in the same sample. Fine-grained, compositionally heterogeneous rhabdophane is accompanied by minor amounts of other paragenetically late, hydrated phosphates with enhanced MREE/HREE relative to LREE (although still LREE-dominant). Minor, relict xenotime and zircon are significant HREE carriers. Ilmenite and pyrochlore group members contain REE but contribute only negligibly to the overall REE budget. Although the proportions of individual mineral species differ, the chemistry of key ore components are similar in different laterite samples from the current resource. Mineral signatures are, however, subtly different in the lower grade southeastern part of the deposit, including higher concentrations of HREE relative to LREE in monazite, rhabdophane, florencite and Fe-(Mn)-(hydr)oxides.

Down-hole fractionation (DHF), a known phenomenon in static spot laser ablation, remains one of the most significant sources of uncertainty for laser-based geochronology. A given DHF pattern is unique to a set of conditions, including material, inter-element analyte pair, laser conditions, and spot geometry. Current modelling methods (simple or multiple linear regression, spline-based regression) for DHF do not readily lend themselves to uncertainty propagation, nor do they allow for quantitative inter-session comparison, let alone inter-laboratory or inter-material comparison. In this study, we investigate the application of orthogonal polynomial decomposition for quantitative modelling of LA-ICP-MS DHF patterns. We outline the algorithm used to compute the models, apply it to an exemplar U–Pb dataset across a range of materials and analytical sessions, and finally provide a brief interpretation of the resulting data. In this contribution we demonstrate the feasibility of quantitative modelling and comparison of DHF patterns from multiple materials across multiple sessions. We utilise a relatively new data visualisation method, uniform manifold approximation and projection (UMAP), to help visualise the data relationships in this large dataset while comparing it to more traditional methods of data visualisation. The algorithm presented in this research advances our capability to accurately model LA-ICP-MS DHF and may facilitate reliable decoupling of the DHF correction for non-matrix-matched materials, lead to improved uncertainty propagation, and facilitate inter-laboratory comparison studies of DHF patterns. The generalised nature of the algorithm means it is applicable not only to geochronology but also more broadly within the geosciences where predictable linear (x-to-y) relationships exist.

The glaciogenic nature of the Yudnamutana Subgroup was first recognized over a century ago, and its global significance was recognized shortly after, with the eventual postulation of a global Sturtian Glaciation and Snowball Earth theory. Much debate on the origin and timing of these rocks, locally and globally, has ensued in the years since. A significant corpus of research on the lithology, sedimentology, geochronology and formal lithostratigraphy of these sequences globally has attempted to resolve many of these debates. In the type area for the Sturtian Glaciation, South Australia's Adelaide Superbasin, the lithostratigraphy and sedimentology are well understood; however, formal stratigraphic nomenclature has remained complicated and contested. Absolute dates on the stratigraphy are also extremely sparse in this area. The result of these longstanding issues has been disagreement as to whether the sedimentary rocks of the Yudnamutana Subgroup are truly correlative throughout South Australia, and if they were deposited in the same time span recently defined for Sturtian glacial rocks globally, c. 717 Ma to c. 660 Ma. This study presents a large detrital zircon study, summarizes and compiles existing global geochronology for the Sturtian Glaciation and revises the formal lithostratigraphic framework of the Yudnamutana Subgroup. We show equivalence of the rocks that comprise the revised Sturt Formation, the main glaciogenic unit of the Yudnamutana Subgroup, and that it was deposited within the time span globally defined for the Sturtian Glaciation.

In complex metamorphic rocks, monazite U–Pb dates can span a wide concordant range, leading to ambiguous geological interpretations (e.g. slow protracted cooling versus multiphase growth). We present in situ monazite Lu–Hf analysis as an independent chronometer to verify U–Pb age interpretations. Monazite Lu–Hf dates were attained via laser ablation inductively coupled plasma mass spectrometry equipped with collision/reaction cell technology (LA-ICP-MS/MS). In situ Lu–Hf dates for potential reference monazites with uncertainties <1.6 % agree with published U–Pb dates, validating the approach. We demonstrate the method on complex metamorphic samples from the Arkaroola region of the northern Flinders Ranges, South Australia, which exhibit protracted thermal and monazite growth histories due to high geothermal gradient metamorphism. In situ Lu–Hf dates reproduce the main U–Pb monazite age populations, demonstrating the ability to reliably resolve multiple age populations from polymetamorphic monazite samples.