Seasonal assessment of the structural and functional potential of microbial communities was conducted in a full-scale vertical-flow wetland for combined sewer overflow treatment (CSO-TW). The filter bed extending over 2000 m2 was sampled in four different layers along its vertical and horizontal expansion. Biofilm extracted from the filter substrate was subject to community-level physiological profiling to evaluate metabolic activity in winter and early summer, and 16S ribosomal RNA (rRNA) amplicon sequencing to further examine the microbial community structure in winter.The first-time investigation at this scale revealed that while the hydraulic flow had a measurable impact on the spatial metabolic activity, seasonal effects remained limited, supporting prior findings that CSO-TWs offer stable water treatment performance throughout the year. Results from 16S rRNA sequencing showed a similar hydraulic impact, but contrasting conclusions from the comparison with a parallel study on a pilot-scale CSO-TW underline the importance of using mature pilot-scale systems for adequate representation of effects on full-scale sites. Currently, investigations on pilot-scale studies often rely on young systems due to short project durations and funding cycles, which allow only for limited conclusions to the situation in matured full-scale systems.Further comparison with investigations on vertical-flow treatment wetlands treating domestic wastewater revealed similarities in microbial communities across studies despite varying designs, size and influent water. This is encouraging for further and more widely comparison and insight to clearly determine the microbial functional responses. It also points to the adaptive nature of TWs to water treatment requirements.

The rocks of the Rakiraki volcano along the Nakavadra River in Fiji are being studied to understand the complex magmatic differentiation processes associated with them. In the River section, basalts and basaltic breccias are intruded by trachybasalt dikes. The presence of felsic and mafic magmatic enclaves with chilled margins, as well as chilled margins at the trachybasalt dike in contact with basalt lava, suggests magma mixing and mingling. Plagioclase and the host trachybasalt dike rock show similar rare earth element patterns, although plagioclase has lower concentrations and a positive Eu anomaly. Variable anorthite contents in plagioclase indicate crystallization at different depths or possible magma replenishments. This concept is supported by the clinopyroxene composition, which exhibits Mg- and Cr-rich 'mantled zones' relative to its core and rim. An initial pulse of mantle-derived basaltic magma likely accumulated at the MOHO level before rising and ponding at crustal depths, crystallizing clinopyroxene, and plagioclase. Later, basaltic magma enriched in Cr, Mg, and Fe replenished the chamber at crustal levels, ultimately leading to eruption. The melt fractionated from the basalt intruded as trachybasalt dikes. Both enriched and depleted patterns of whole-rock rare-earth elements suggest that enriched and depleted melts contributed to the origin of the Rakiraki volcanics. Thus, crystal fractionation with periodic replenishment of basaltic magma contributed to the formation of the rocks along the Nakavadra River, producing rocks that display both LREE-depleted MORB- and enriched arc-type trace-element characteristics.

Mica crystals have a highly asymmetric structure, arranged in sheets of two tetrahedral layers bonded to a single octahedral layer. The individual sheets are only weakly bonded, leading to perfect basal cleavage. The recent proliferation of in situ laser ablation-based Rb-Sr geochronology of mica makes it critical to understand if orientation of the crystal lattice relative to the laser beam may impart a differential 'matrix' effect on Rb-Sr ratios during ablation. Analyses of mica crystals from eight different samples, including biotite, muscovite and phlogopite, mounted with their c-axes approximately parallel (flat-mounted) and perpendicular (vertically mounted) to the incident laser beam, result in dates that are statistically indistinguishable. Moreover, and consistent with previous work, analysis of vertically mounted crystals generally resulted in less within-spot variation in 87Rb/86Sr, and is, therefore, the recommended orientation for Rb-Sr geochronology measurements, where practical.

The Late Triassic Burgundy porphyry system in the Golden Triangle of northwest British Columbia, Canada hosts Cu-Au mineralization in multiple prospective centers. Preliminary geologic mapping of the surface expression of the prospect and a cross section through the southern extension at The Ridge provide a preliminary structural understanding of the system with respect to the surrounding host rocks. The porphyries that make up the Burgundy prospect are emplaced into Upper Stikine Assemblage to Lower Stuhini Group strata with discrete episodes of texturally and geochemically distinct porphyry emplacement and igneous/hydrothermal brecciation. Lithogeochemical data indicate the prospect is a silica-undersaturated alkalic porphyry system consistent with the ubiquitous absence of quartz. A complex history of potassic, calc-potassic, phyllic, and propylitic alteration events overprint the porphyries, breccias, and wallrocks. The age of alteration was determined using in situ U-Pb and Rb-Sr geochronology. Titanite U-Pb (212.8 [+2.6] to 208.6 [+1.9] Ma), apatite U-Pb (216.7 [+2.9] to 208.2 [+4.1] Ma), garnet U-Pb (215.1 [+1.3] to 211.4 [+0.95] Ma), and biotite Rb-Sr (218.9 [+5.4] to 200.5 [+0.5] Ma) ages are interpreted alongside trace and major element geochemistry to reflect the timing of hydrothermal precipitation and/or equilibration of the dated phases during infiltration of hydrothermal fluids. The geochronology results define a minimum emplacement age for the porphyry suite and outline a protracted period (>10 Myr) of localized, likely episodic, post-emplacement hydrothermal alteration/equilibration. The oldest ages from apatite (216.7 + 2.9 Ma), garnet (215.1 + 1.3 Ma), and biotite (218.9 + 5.4 Ma) indicate emplacement of Burgundy porphyries began before emplacement of the neighboring Galore Creek alkalic suite (212-205 Ma). In addition, the youngest biotite date (200.5 + 0.5 Ma) indicates Burgundy experienced localized high-T hydrothermal fluid infiltration associated with either a long-lived hydrothermal system related to cooling of structurally deeper Burgundy melts and/or externally derived fluids during the onset of local Tatogga/Texas Creek suite magmatism. The new age data from Burgundy indicate alkalic magmatism in the Golden Triangle began earlier than is currently recognized within the working regional framework model and that Burgundy was a conduit for protracted hydrothermal activity during this critical metallogenic epoch near the Triassic-Jurassic boundary.

New in situ apatite U-Pb and mica Rb-Sr and Ar-40/Ar-39 geochronology outline a break in geochronology within the Mount Everest massif at an elevation of c. 8000 m. Above the break, most chronometers record dates from the Eocene epoch, whereas below, most dates are from the Middle Miocene epoch. Raman spectroscopy of carbonaceous material and Ti-in-biotite-based thermometry results outline a break in temperatures at the same elevation. From the summit downwards, temperatures increase to a maximum of c. 500 degrees C at c. 8500 m before decreasing to c. 400 degrees C at c. 7900 m. The coinciding breaks in the independent datasets are interpreted to reflect movement along a previously unrecognized structure, here termed the Adrishya thrust that was active c. 18 Ma. The Adrishya thrust may reflect re-equilibration of the evolving orogenic wedge, perhaps further influenced by cooling and strain localization structurally away from the exhuming orogenic core.

Re-examination of sediment samples collected from the Bay of Bengal via laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) Rb-Sr geochronology demonstrates the viability of the Rb-Sr system for use as a detrital chronometer. The age population defined by the Rb-Sr dates essentially reproduces that previously published for detrital 40Ar/39Ar dates. The assumed initial 87Sr/86Sr on the calculated population has some influence on the age of the final population, but that influence can be ameliorated by filtering for higher 87Rb/86Sr ratios. The 87Rb/86Sr ratio cut-off used for such filters to minimize the effect of initial 87Sr/86Sr on the final population is strongly dependant on the age of the material being analysed (i.e. ~> 87Rb/86Sr = 500 @ 250 Ma and ~>87Rb/86Sr = 50 @ 2500 Ma). Finally, Ti-in-biotite temperatures calculated based on data collected during LA-ICP-MS overlap with those calculated for the same material based on electron probe microanalyzer data demonstrating the potential for petrochronolgy based on the Rb-Sr system.

Re-examination of three specimens from the Kanchenjunga Himal of Nepal via in situ Lu-Hf garnet geochronology yields evidence of multiple garnet growth events. Spot analyses from grain cores in two specimens define Paleozoic regressions whereas analyses from grain rims in the same specimens define low-precision regressions consistent with the timing of Himalayan orogenesis. These dates contrast with previously published low dispersion, ca. 290 Ma isotope dissolution (ID) Lu-Hf garnet dates for the same rocks. Modelling of Lu and spot age distribution in representative grains from the specimens examined yields calculated dates that approximate the Permian-age regressions through the original ID data. These findings demonstrate that it is possible to generate low dispersion ID Lu-Hf data from multi-generational garnet with significantly different-age growth events when approximately equal proportions of the different age reservoirs are included in multi-component aliquots.

Trace metal and rare earth element (REE) abundances in banded iron formations are critical for assessing the chemical composition of ancient seawater and the long-term evolution of the ocean-atmosphere system. Recent studies, however, have highlighted the potential effects of outcrop weathering, raising concerns about whether banded iron formation samples are suitable proxies for ancient redox conditions or if exposure to surficial weathering regimes may have altered key geochemical signals. Here, we present a detailed, high-resolution study of several banded iron formation outcrop samples from the Hamersley Basin, Western Australia, to investigate microscale differences in composition between banded iron formation and weathered surfaces (i.e., weathered crusts). Elemental mapping and bulk-rock geochemical analyses reveal that weathered crust is more enriched in most elements than the banded iron formation, except for silica, which is significantly depleted. There is also a significant loss of redox-sensitive elements (RSEs) in the weathered surface, which suggests that outcrop samples have been affected by higher degrees of chemical leaching than physical erosion. These results are significant, because we clearly show that the geochemical characteristics of the weathered surface—irrespective of how it formed—are distinct from those of the remainder of the sample. This means that with sufficient screening of samples for obvious signs of alteration, banded iron formation outcrop samples may indeed be used as a reliable proxy for the evolution of Earth’s coupled ocean-atmosphere system. This increases the volume of easily accessible Precambrian sample material, so that researchers no longer solely need to rely on core recovered through costly drilling programs.

The problem of excess 40Ar (ArE) affecting 40Ar/39Ar dates, particularly in biotite, is a long-standing issue in Himalayan geology. The development of in situ Rb-Sr dating presents a convenient alternative method to extract geochronological data from the same material and avoids potential ArE complications. Herein we present a comparison between previously published 40Ar/39Ar data, including many interpreted to reflect ArE, and new in situ Rb-Sr analyses for the same specimens. This work demonstrates that Rb-Sr mica dates from across the exhumed Himalayan metamorphic core typically overlap 40Ar/39Ar dates from the same rocks that are unaffected by ArE. Where 40Ar/39Ar dates have been interpreted to reflect ArE, the Rb-Sr method invariably yields dates that are younger than the ArE date and consistent with other mineral chronometer systems. Finally, while further refinement is required, we propose a technique to extract spot ages for high Rb/low Sr biotite analyses, by correcting for common 87Sr based on the present known ratio of 87Sr/88Sr, removing the need to assume an initial 87Sr/86Sr.

The putative Jambil meta-carbonatites of Swat, northern Pakistan, occur as discrete intrusions into the Proterozoic Manglaur Formation, which are difficult to be distinguished from nearby calc-silicate marble because both rock types experienced regional metamorphism during Himalayan orogenesis that resulted in similar mosaic textures and mineral assemblages. Carbonatites are often significant repositories of economic mineral resources and, therefore, are important to be distinguished from calc-silicate marble. We present new geochemical and geochronology data to distinguish between the two rock types and interpret the petrogenesis and tectonic evolution of the Jambil meta-carbonatites. Whole rock chemical data from the Jambil meta-carbonatites show characteristically high rare earth element (REE), Sr contents and lack of negative Eu anomaly, consistent with average calcio-carbonatite values worldwide and an igneous origin. More than 0.5 wt.% SrO in the meta-carbonatites and SrO > 0.15 wt.% in constituent rock forming calcite are discriminating signatures of the Jambil meta-carbonatites. Chemically, the Jambil meta-carbonatites are relatively depleted in Rb, Nb, Ta, Ti, Zr and Hf, relatively enriched in Ba, Th, Sr, and have a high LREE/HREE ratio when normalized to primitive mantle. Their carbon and oxygen isotope compositions vary from −3.5‰ to −4.3‰ and from 9.7‰ to 12.3‰, respectively. These geochemical characteristics indicate generation of the carbonatites through small degree of partial melting from a carbonated eclogitic source. In-situ , U/Pb analysis of titanite indicates that the Jambil meta-carbonatites were emplacement at 438 ± 3 Ma. When combined with regional geological observations, we interpret the emplacement of the Jambil meta-carbonatites to have taken place during the Silurian back arc extension within greater Gondwana and mark a transition from a compressional tectonic regime, brought about by collision of microcontinental blocks along the northern margin of Gondwana, to post-orogenic extension in the waning stages of the pre-Himalayan Ordovician orogeny. Finally, in-situ 208 Pb/ 232 Th monazite dates (40.3−27.6 Ma) extracted from the meta-carbonatites are consistent with the Cenozoic metamorphism of the area.

Silver nanomaterials (Ag NMs) have been used in a variety of commercial products to take advantage of their antimicrobial properties. However, there are concerns that these AgNMs can be released during/after use and enter wastewater streams, potentially impacting aquatic systems or accumulating in wastewater biosolids. Biosolids, which are a residual of wastewater treatment processes, have been found to contain AgNMs and are frequently used as agricultural fertilizer. Since the function of soil microbial communities is imperative to nutrient cycling and agricultural productivity, it is important to characterize and assess the effects that silver nanomaterials could have in agricultural soils. In this study agricultural soil was amended with pristine engineered (PVP-coated or uncoated AgNMs), aged silver (sulphidized or released from textiles) nanomaterials, and ionic silver to determine the fate and toxicity over the course of three months. Exposures were carried out at various environmentally relevant concentrations (1 and 10 mg Ag/kg soil) representing between 30 to over 800 years of equivalent biosolid loadings. Over thirteen different methodologies and measures were used throughout this study to assess for potential effects of the silver nanomaterials on soil, including microbial community composition, average well colour development (AWCD) and enzymatic activity. Overall, the AgNM exposures did not exhibit significant toxic effects to the soil microbial communities in terms of density, activity, function and diversity. However, the positive ionic silver treatment (100 mg Ag/kg soil) resulted in suppression to microbial activity while also resulting in significantly higher populations of Frankia alni (nitrogen-fixer) and Arenimonas malthae (phytopathogen) as compared to the negative control (p < 0.05, Tukey HSD) which warrants further investigation.

When the SEGH international board released a short editorial paper back in 2019, we described an aim to increase the membership offering, whilst improving the diversity of input regionally, by scientific discipline and to ensure greater and more regular contact across the regions from 2020 onwards. Wider aspirations described in 2019 (Watts et al. 2019) are discussed within this short communication at the end of 2021 to evaluate progress made. In particular, how the SEGH community adapted to the unprecedented circumstances that have challenged each and every one of us throughout the COVID-19 pandemic since early 2020 and are likely to influence our activities for the foreseeable future.

Subduction zones are first-order features of plate tectonics on Earth, yet the mechanisms by which subduction initiates remain enigmatic and controversial. Here, we reappraise the timing of metamorphism of the rock units first detached from the leading edge of the downgoing slab during initiation of the Neotethys subduction, now preserved in the metamorphic sole of the Semail ophiolite (Oman–United Arab Emirates). Using petrochronology and phase equilibrium modeling, we demonstrate that subduction initiated prior to 102–100 Ma at a slow rate (< 1 cm/yr). Subduction stagnated at relatively warm conditions (15–20 °C/km) for > 5 Myr before evolving into a faster (≥ 2–5 cm/yr) and colder (∼7 °C/km) self-sustained regime. Subduction acceleration (i.e. “unlocking” stage) triggered the onset of slab retreat, large-scale corner flow and fast ocean spreading in the overriding plate at 96–95 Ma, through the progressive change of thermo-mechanical structure of the plate interface. This study reconciles conflicting analogue and numerical subduction initiation models, shedding light on the thermal, mechanical and kinematic complexity of subduction initiation.

Subduction zones are crucial features of Earth’s plate tectonics, yet subduction initiation remains enigmatic and controversial. Herein, we reappraise the timing of formation of the first fragments detached from the leading edge of the downgoing slab during subduction initiation (i.e., the Semail metamorphic sole; Oman–United Arab Emirates). Based on geochronology and phase equilibrium modeling, we demonstrate that subduction initiated prior to 105 Ma and at a slow pace (< cm/yr). Subduction stagnated at relatively warm conditions (15–20°C/km) for at least 10 Myr before evolving into a faster (≥ 2–5 cm/yr) and colder (~7°C/km) self-sustained regime. Subduction unlocking at 95-96 Ma, through the progressive change of the interplate thermo-mechanical structure, triggered the onset of slab retreat, large-scale corner flow and fast ocean spreading in the overriding plate. These results reconcile conflicting analogue and numerical subduction initiation models and reveal the thermal, mechanical and kinematic complexity of early subduction steps.

Magmatic and tectonic processes can transport large volumes of magma generated in the deep crust as discrete pulses to shallower crustal depths, resulting in the incremental construction of large, composite batholiths over thousands to tens of millions of years. The Silurian to Early Devonian Donegal composite batholith in Ireland is a classic example of which regional geological syntheses and lithogeochemical data show that emplacement was syn- and post-kinematic with respect to the terminal phases (ca. 437−415 Ma) of the Caledonian orogeny. We used U-Pb dating of zircon and titanite to investigate the construction of the batholith over time. Imaging of these minerals reveals complex, zoned grains with distinct autocrystic (growth during pluton emplacement) and antecrystic (growth during lower crustal incubation) domains as well as xenocrysts (incorporated from wall rocks). To determine the ages of emplacement and of inherited domains, discrete growth zones were targeted for dating using laser ablation−inductively coupled plasma−mass spectrometry (LA-ICP-MS). Taken together, the zircon and titanite U-Pb isotopic data indicate that magmatism occurred over at least 30 m.y., between ca. 430 Ma and 400 Ma. Batholith emplacement is bracketed by the ca. 427−423 Ma Ardara pluton and the latest phases in the Main Donegal and Trawenagh Bay plutons (ca. 400 Ma). Although apparently volumetrically minor, U-Pb data from spatially associated mafic rocks (appinite suite, lamprophyre dikes, and mafic enclaves in granitoid plutons) yield ages ranging from ca. 431−416 Ma, which indicates ongoing mafic magmatism during emplacement of much of the Donegal composite batholith.

The challenges of sustainable development are ever more pressing, and the skills, interests and capabilities of the SEGH member are well-placed to continue to make more meaningful contributions to the environment, society and well-being.We reflect on the historical development of the society, its response to the dynamic international research landscape and the great opportunities ahead.In 2018, SEGH implemented a new board structure after 2-3 years of consultation, with approval of a new constitution and a new strategy across the large number of international board members.While regions were represented by

Metamorphic soles are m to ~500 m thick tectonic slices welded beneath most large- scale ophiolites (usually ~20 km thick). They typically show a steep inverted metamorphic structure where the pressure and temperature (T) conditions of crystallization increase upward, from the base of the sole (500 ± 100°C at 0.5 ± 0.2 GPa) to the contact with the overlying peridotite (800 ± 100°C at 1.0 ± 0.2 GPa). The inverted T gradient was historically interpreted as a result of heat transfer from the incipient mantle wedge toward the nascent slab synchronously with the overlying ophiolite formation (within only 1-2 Myrs). Their mineralogical assemblage and deformation pattern provide major constraints on the nature and the timing of the processes controlling the dynamics of the plate interface during early subduction. Soret et al. (2017, 2019) recently reappraised the tectonic–petrological model for the formation of metamorphic soles below ophiolites, showing that the present-day structure of the sole results from the successive stacking of several homogeneous oceanic crustal slivers (without internal T gradient). This stacking marks the evolution of rheological properties of slab material and peridotites of the upper plate as the plate interface progressively cools (Agard et al., 2016). These findings outline the thermal and mechanical complexity of early subduction dynamics, and highlight the need for refined numerical modelling studies. Lu-Hf geochronology on garnet from the Oman metamorphic sole has recently shown that the earliest accreted subunit, found directly against the upper plate mantle, was initially buried ≥ 8 Ma earlier than previously estimated (Guilmette et al., 2017). These results imply initiation ≥ 8 Ma before the formation of the ophiolite, which underscores the common belief that ophiolite-sole couples record spontaneous subduction initiation and rather indicates far-field forcing long before upper plate extension and mantle upwelling. We herein present new U-Pb titanite and monazite petrochronology across the different sub-units of the Oman metamorphic sole. Our results confirm the time lag of several million years between subduction initiation and the ophiolite formation, therefore supporting the recently proposed model of far-field forced subduction initiation. They also reveal a significant time lag between the underplating and exhumation of each sub-unit of the sole.

Uptake, distribution and speciation of arsenic (As) were determined in the bracket fungus Fomitopsis betulina (previously Piptoporus betulinus), commonly known as the birch polypore, collected from a woodland adjacent to a highly contaminated former mine in the Southwest UK and at an uncontaminated site in Quebec, Canada, with no past or present mining activity. The fruiting body was divided into cap, centre and pores representing the top, middle and underside to identify trends in the distribution and transformation of As. Total As, determined by inductively coupled plasma–mass spectrometry (ICP–MS), was approximately tenfold higher in the mushroom from the contaminated compared to the uncontaminated site. Overall, accumulation of As was low relative to values reported for some soil-dwelling species, with maximum levels of 1.6 mg/kg at the contaminated site. Arsenic speciation was performed on aqueous extracts via both anion and cation high-performance liquid chromatography–ICP–MS (HPLC–ICP–MS) and on whole dried samples using X-ray absorption near edge structure (XANES) analysis. Seven As species were detected in F. betulina from the contaminated site by HPLC–ICP–MS: arsenite (AsIII), arsenate (AsV), dimethylarsinate (DMAV), methylarsonate (MAV), trimethylarsine oxide (TMAO), tetramethylarsonium ion (Tetra) and trace levels of arsenobetaine (AB). The same As species were observed at the uncontaminated site with the exception of TMAO and Tetra. Arsenic species were localized throughout the fruiting body at the contaminated site, with the cap and pores containing a majority of AsV, only the cap containing TMAO, and the pores containing higher concentrations of DMAV and MAV as well as tetra and a trace of AB. XANES analysis demonstrated that the predominant form of As at the contaminated site was inorganic AsIII coordinated with sulphur or oxygen and AsV coordinated with oxygen. This is the first account of arsenic speciation in F. betulina or any fungi of the family Fomitopsidaceae.

Combined sewer overflows are contaminatedwith variousmicropollutants which pose risk to both environmental and human health. Some micropollutants, such as carbamazepine and sulfamethoxazole, are very persistent and difficult to remove from wastewater. Event loaded vertical-flow constructed wetlands (retention soil filters; RSFs) have proven to be effective in the treatment of combined sewer overflows for a wide range of pollutants. However, little is known about how microbial communities contribute to the treatment efficiency, specifically to the reduction of micropollutants. To the best of our knowledge, this is the first study attempting to close this gap. Microbial communities in pilotscale RSFs were investigated, which showed explicit grouping of metabolic activity at different filter depths with some differential abundance of identified genera. The highest microbial activity was found in the top layer of 0.75m deep filters, whereas homogeneous activity dominated in a 0.50 m deep filter, indicating oxygen availability to be a limiting factor of the metabolic activity in RSFs. The removal efficiencies of all investigated organic trace substanceswere correlated to the utilization of specific carbon sources. Most notable is the correlation between the carbon source glucose-1-phosphate and the removal of metoprolol. The strongest correlations for other substances were the removal of diclofenac to the utilization of the carbohydrate i-erythritole; bisphenol A to carbohydrate a-D-lactose, and 1-H-benzotriazole to carbonic acid D-galacturonic acid. Those results are supported by positive correlations of specificmicrobial genera with both the utilization of the above mentioned carbon sources and the removal efficiency for the respective micropollutants. Most notable is correlation of Tetrasphaera and the removal of benzotriazole and diclofenac. (C) 2020 Elsevier B.V. All rights reserved.