A review of the geology and geodynamic evolution of the Palaeoproterozoic Earaheedy Basin, Western Australia

The Palaeoproterozoic Earaheedy Basin is one of a series of basins that extend for about 700 km east-west and are part of the Capricorn Orogen, situated between the Archaean Pilbara and Yilgarn Cratons. The Earaheedy Basin contains sedimentary rocks that were deposited on the northern passive continental margin of the Yilgarn Craton, probably as a result of continental breakup at 1.8 Ga. The sedimentary rocks of the Earaheedy Group are divided into two Subgroups, Toloo and Miningarra, each representing different depositional environments and aggregating about 3000 m in thickeness. The Tooloo Subgroup consists of basal siliciclastic with minor platform carbonates, overlain by a 600-m-thick succession of Fe-rich rocks (granular iron-formation and hematitic shales). The Miningarra Subgroup is predominantly siliciclastic, but includes stromatolite-bearing carbonate sequences and was deposited during a more active depositional regime. Far field tectonic events at 1.76 and 1.65 Ga resulted in the deformation of the sedimentary package with progressive intensity from north to south, forming the Stanley Fold Belt and giving and overall asymmetric structure to the Basin. These events were followed by a large meteorite impact (Shoemaker Impact Structure), probably in the Neoproterozoic. The Earaheedy Basin is well endowed with Fe resources, represented by the granular iron-formation (Frere Formation, Tooloo Subgroup), particularly in the Stanly Fold Belt, where there was secondary enrichement

In Situ U–Pb Monazite and Xenotime Geochronology of the Abra Polymetallic Deposit and Associated Sedimentary and Volcanic Rocks, Bangemall Supergroup, Western Australia

Abra is a major lead–silver–copper–gold deposit within the Bangemall Supergroup that has a total indicated and inferred resource estimate of 93 million tonnes at 4.0% lead and 10 g/t silver and 14 million tonnes at 0.6% copper and 0.5 g/t gold. The mineralization lies within the upper part of the locally defi ned Gap Well Formation, and in the lower part of the overlying West Creek Formation. These units correlate respectively with the Irregully and lower Kiangi Creek Formations of the Edmund Group.The Abra deposit is characterized by a funnel-shaped brecciated zone, interpreted as a breccia feeder-pipe, overlain by stratabound mineralization made up of the Red Zone, an underlying Black Zone, and a stringer (feeder) zone. The Red Zone is characterized by banded jaspilite, hematite, galena, pyrite, quartz, abundant barite, and siderite. The Black Zone consists of veins and rhythmically banded Pb, Zn, and minor Cu sulfi des, laminated and/or brecciated hematite, magnetite, Fe-rich carbonate, barite, and scheelite.In situ Sensitive high-resolution ion microprobe (SHRIMP) U–Pb geochronology of detrital zircon, monazite, and xenotime in sandstones from the Abra deposit yields a range of dates from c. 2450 Ma to c. 1675 Ma, consistent with results from previous detrital zircon studies. SHRIMP dating of hydrothermal monazite from the Abra deposit suggests that a mineralization event occurred at c. 1385 Ma. The presence of c. 1465 Ma metamorphic/hydrothermal monazite in sandstones from Abra indicates that the host rocks are older and therefore belong to the Edmund Group. SHRIMP geochronology of xenotime extracted from the Tangadee Rhyolite, which outcrops within the lower Kiangi Creek Formation close to the Abra deposit, yields two main age components corresponding to oscillatory-zoned cores and unzoned rims. The cores are interpreted as magmatic in origin and indicate a possible eruption age of c. 1235 Ma, whereas the rims are interpreted to record a later hydrothermal event at c. 1030 Ma. If this interpretation is correct, then the sedimentary succession containing the rhyolite is younger than the Edmund Group (1465 Ma), and may belong to the basal Collier Group (1070 Ma) although the geological setting does not support this

Fenites associated with carbonatite complexes : a review

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Carbonatites and alkaline-silicate rocks are the most important sources of rare earth elements (REE) and niobium (Nb), both of which are metals imperative to technological advancement and associated with high risks of supply interruption. Cooling and crystallizing carbonatitic and alkaline melts expel multiple pulses of alkali-rich aqueous fluids which metasomatize the surrounding country rocks, forming fenites during a process called fenitization. These alkalis and volatiles are original constituents of the magma that are not recorded in the carbonatite rock, and therefore fenites should not be dismissed during the description of a carbonatite system. This paper reviews the existing literature, focusing on 17 worldwide carbonatite complexes whose attributes are used to discuss the main features and processes of fenitization. Although many attempts have been made in the literature to categorize and name fenites, it is recommended that the IUGS metamorphic nomenclature be used to describe predominant mineralogy and textures. Complexing anions greatly enhance the solubility of REE and Nb in these fenitizing fluids, mobilizing them into the surrounding country rock, and precipitating REE- and Nb-enriched micro-mineral assemblages. As such, fenites have significant potential to be used as an exploration tool to find mineralized intrusions in a similar way alteration patterns are used in other ore systems, such as porphyry copper deposits. Strong trends have been identified between the presence of more complex veining textures, mineralogy and brecciation in fenites with intermediate stage Nb-enriched and later stage REE enriched magmas. However, compiling this evidence has also highlighted large gaps in the literature relating to fenitization. These need to be addressed before fenite can be used as a comprehensive and effective exploration tool.This research has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 689909

Evidence for early life in Earth’s oldest hydrothermal vent precipitates

Although it is not known when or where life on Earth began, some of the earliest habitable environments may have been submarine-hydrothermal vents. Here we describe putative fossilized microorganisms that are at least 3,770 million and possibly 4,280 million years old in ferruginous sedimentary rocks, interpreted as seafloor-hydrothermal vent-related precipitates, from the Nuvvuagittuq belt in Quebec, Canada. These structures occur as micrometre-scale haematite tubes and filaments with morphologies and mineral assemblages similar to those of filamentous microorganisms from modern hydrothermal vent precipitates and analogous microfossils in younger rocks. The Nuvvuagittuq rocks contain isotopically light carbon in carbonate and carbonaceous material, which occurs as graphitic inclusions in diagenetic carbonate rosettes, apatite blades intergrown among carbonate rosettes and magnetite–haematite granules, and is associated with carbonate in direct contact with the putative microfossils. Collectively, these observations are consistent with an oxidized biomass and provide evidence for biological activity in submarine-hydrothermal environments more than 3,770 million years ago

Personalizing Cancer Pain Therapy: Insights from the Rational Use of Analgesics (RUA) Group

Introduction: A previous Delphi survey from the Rational Use of Analgesics (RUA) project involving Italian palliative care specialists revealed some discrepancies between current guidelines and clinical practice with a lack of consensus on items regarding the use of strong opioids in treating cancer pain. Those results represented the basis for a new Delphi study addressing a better approach to pain treatment in patients with cancer. Methods: The study consisted of a two-round multidisciplinary Delphi study. Specialists rated their agreement with a set of 17 statements using a 5-point Likert scale (0 = totally disagree and 4 = totally agree). Consensus on a statement was achieved if the median consensus score (MCS) (expressed as value at which at least 50% of participants agreed) was at least 4 and the interquartile range (IQR) was 3–4. Results: This survey included input from 186 palliative care specialists representing all Italian territory. Consensus was reached on seven statements. More than 70% of participants agreed with the use of low dose of strong opioids in moderate pain treatment and valued transdermal route as an effective option when the oral route is not available. There was strong consensus on the importance of knowing opioid pharmacokinetics for therapy personalization and on identifying immediate-release opioids as key for tailoring therapy to patients’ needs. Limited agreement was reached on items regarding breakthrough pain and the management of opioid-induced bowel dysfunction. Conclusion: These findings may assist clinicians in applying clinical evidence to routine care settings and call for a reappraisal of current pain treatment recommendations with the final aim of optimizing the clinical use of strong opioids in patients with cancer

Ar-Ar geochronology of a pseudotachylite sample from the Yarrabubba impact structure, Western Australia

Meteorite impacts cause conversion of kinetic energy into thermal energy. Part of this thermal energy is used to form a melt sheet, part is dissipated to heat the target rocks and these together with the hot rocks that elastically rebound from the depth of several kilometres (central uplift) activate hydrothermal circulation. Impact-generated hydrothermal systems have been documented from several impact structures world-wide. Three Australian examples—Shoemaker, Woodleigh and Yarrabubba—provide evidence of hydrothermal fluid flow both within and around the structures. Field observations, and petrographic and geochemical data suggest a common evolutionary trend of post-impact hydrothermal activity from early high-temperature alkali metasomatism to a later lower temperature H + metasomatism, resulting in the overprinting by hydrous mineral assemblages. Hydrothermal systems activated by meteorite-impact events are important because they may also form economic mineral deposits, as is documented for several impact structures in the world. A working model of hydrothermal circulation in terrestrial impact structures posits two main stages: (i) initial high-temperature fluids percolate downward causing widespread alkali metasomatism of the shattered target rocks below the melt sheet, resulting in their modification to rocks of syenitic affinity; and (ii) inflow of meteoric water and progressive cooling of the melt sheet leads to a lower temperature stage, in which hydrothermal fluid flow tends to move upward, resulting in mineral assemblages and alteration patterns that resemble those of epithermal systems. In addition, these fluids can discharge at the surface as hot springs