The Statherian period was critical for the assembly of the Columbia supercontinent and is widely recorded in the Amazon Craton. The Western Amazonia Igneous Belt (WAIB) was formed by silicicdominated magmatic events between similar to 1815 Ma and 1740 Ma. By combining literature geochemical-isotopic data with new results, we refine the spatio-temporal framework of the WAIB. The igneous record is subdivided into three bimodal (basalt-ferroan silicic rocks) associations: Event 1 (1815-1780 Ma), the most voluminous, consists of OIB-like tholeiitic basalts and silicic rocks with variable Ga/Al ratios, interbedded with fluvial-lacustrine sedimentary rocks. This event reflects hotter and deeper basaltic sources contemporaneous with high-temperature silicic magmatism; its peak (1790-1780 Ma) coincides with the emplacement of the Avanavero Large Igneous Province (LIP). Event 2 (1780-1760 Ma), less voluminous and restricted to the southwestern WAIB, comprises E-MORB-like basalts derived from cooler and shallower sources, along with lower-temperature silicic rocks showing low Ga/Al ratios, and is associated with marine and fluvial sedimentation. Event 3 (1760-1740 Ma) marks a decline in igneous activity and the onset of rifting, with small-volume volcanism interbedded with deltaic to coastal sediments. The high volumes, short duration, and intraplate affinities of Events 1 and 2 are consistent with a silicic LIP emplaced as a LIP-shirker event. WAIB evolution shows no evidence of arc-related magmatism and was not followed by continental breakup. Instead, it suggests that LIP activity was the main driver of crustal growth and contributed significantly to continental stabilization during Columbia's assembly. (c) 2026 China University of Geosciences (Beijing) and Peking University. Published by Elsevier B.V. on behalf of China University of Geosciences (Beijing). Thi s is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Loose, persistently unstable rubble beds are increasingly common on coral reefs due to climate-driven disturbances and human impacts. These rubble beds often act as bottlenecks to reef recovery and typically do not stabilize without intervention. Rubble stabilization is used globally to restore degraded reefs, but there has been limited synthesis of its effectiveness across methods and environments. A growing need exists to translate current knowledge into practical guidance to support management and improve restoration outcomes. Bayesian Belief Networks (BBNs), useful for modeling complex systems with substantial uncertainty, were applied in this study to support decision-making in rubble stabilization. The model integrates expert knowledge and global data on restoration outcomes over time and in various environments. This study compares coral cover benefits of stabilization methods, including Reef Bags, flat meshes and grids, elevated frames, and solid structures, with and without coral outplants. Benefits were defined as the difference in coral cover between restoration and control sites, attributable to outplanting or natural recruitment. All methods led to increased benefits over time, though outcomes varied in magnitude and timing. Methods that included outplants generally produced earlier gains in coral cover, but benefits were density-dependent and longer-term outcomes remain uncertain. Higher coral cover benefits were associated with smaller rubble pieces, steeper slopes, and stronger hydrodynamic forces, provided stabilization structures were well anchored and maintained, which is often challenging in practice. Improved long-term monitoring, consistent terminology, and data sharing will be critical to strengthen model reliability and support decision-making in the global reef community.

Low volcanic explosivity index (VEI) eruptions are common occurrences in the Southwest Pacific but, as demonstrated by the 2021/2022 eruption of Hunga Volcano, submerged calderas in the region are also capable of producing much larger and more hazardous eruptions. As such, characterising smaller events from potentially hazardous systems is essential. The 2019 eruption of Volcano-F, a submerged caldera, would likely have gone totally undetected had it not produced a pumice raft that inundated beaches in Fiji and eventually washed up in Australia. New data, acquired 5 months after the eruption, reveal the development of a new vent and the accumulation of at least 3.1*107 m3 bulk volume (dense rock equivalent of 5.6*106 m3) of material on the seafloor. Between 30 and 70% of erupted material entered the raft, while the rest remained near to or was dispersed down-current of the vent. This previously unaccounted for material increases the volume estimate for the eruption, confirming it as a VEI 3 event and highlights the importance of considering not just the floating component of a pumice raft forming eruption for VEI estimation. Geochemical analysis reveals the eruption comprised a homogenous batch of dacitic magma, with compositional characteristics similar to that erupted from the same volcano in 2001, and an until-now-unidentified pumice raft in the Coral Sea in 1964. Volcano-F therefore appears to have had at least three explosive eruptions in the last 60 years, indicating it is significantly at unrest. Repeated eruptions of similar composition and low crystal content magma over decadal to centennial scales indicate the existence of a melt-dominant magma body beneath the volcano. Submerged calderas, like Volcano-F, are common in the wider Southwest Pacific region, with many such calderas producing regular eruptions, implicating active magmatic recharge. Our findings motivate a need to carefully monitor and characterise even apparently small eruptions at this volcano, and others along the Tonga-Kermadec Arc. This is because such eruptions have the potential to subsequently prime or trigger more explosive eruptions and provide critical geochemical evidence about the plumbing system and evolution of the volcano, essential for understanding the diverse hazards they pose.

Sea anemones are venomous animals that rely on their venom for prey capture, defense against predators, and intraspecific competition. Currently, comprehensive molecular and evolutionary analyses of the toxin repertoire for sea anemones are limited by a lack of proteomic data for most species. In this study, proteo-transcriptomic analysis was used to expand our knowledge of the proteinaceous components of sea anemone venom by determining the secreted venom proteome of Calliactis polypus. Electromechanical stimulation was used to obtain the secreted venom of C. polypus. We identified a low complexity proteome that was dominated by toxins with similarity to known neurotoxins, as well as six novel toxin candidates. The novel putative toxin candidates were found to be taxonomically restricted to species from the superfamily Metridioidea. Furthermore, the secreted venom of C. polypus had only three putative toxins in common with the venom of acontia from the same species and little similarity with the secreted venom of closely related species. Overall, this demonstrates that regionalized and lineage-specific variability in toxin abundance is common among sea anemone species. Moreover, the limited complexity of the toxin repertoire found in C. polypus supports the idea that peptide neurotoxins make up the dominant toxin arsenal found in the venom of sea anemones.

Long lava flows exceeding 50 km in length are usually produced during large-volume flood basalt eruptions (>100 to 10,000 km(3)) but can also occur from small to moderate-volume (<30 km(3)) basaltic eruptions in continental intraplate monogenetic volcanic fields. Eruptive volume, therefore, is not an a priori barrier to producing long lava flows. Key factors that promote long lava flows include efficient lava transport systems that minimise heat loss, long-lived and sustained effusion rates to maintain flow advancement, and lava flow across low topographic gradients (<1 degrees-10 degrees) with minimal topographic barriers. Here, we focus on an anomalously young and poorly studied basaltic monogenetic volcanic field in southeast Queensland, Australia, that formed part of the broader intraplate volcanism in eastern Australia since the Late Cretaceous. The Coalstoun Lakes Volcanic Field (CLVF) comprises three lava fields: the Barambah Basalt Flow Field, the Deep Creek Flow Field and the Hunters Hill Flow Field. Basalt from the Barambah Basalt Flow Field has been redated here by Ar-40/Ar-39 analysis of groundmass material, yielding a weighted mean age of 0.520 +/- 0.016 Ma. The Barambah Basalt Flow Field contains most of the eruptive volume and has advanced up to 165 km from the vent. The Hunters Hill and the Deep Creek flow fields are comparatively smaller in volume and have advanced similar to 30 and similar to 20 km from the vent, respectively. Lava tubes are only known from proximal regions and do not appear to be a significant factor in promoting long run-out in the CLVF. Flow confinement and utilisation of existing drainage networks are features of both lava flow fields, and advancement down the sand-based and ephemeral Burnett River significantly promoted long run-out despite low topographic gradients. New whole-rock geochemical data on our CLVF samples indicates that all lavas are hawaiites, a common feature of other Quaternary long lava flows globally. Overall, there is some compositional variation, but a cryptic zonation is readily apparent in trace element abundances, which helps to further distinguish the flow fields as the products of separate but closely spaced eruptions. The combination of field and geochemical data indicates that the long lava flow of the Barambah Basalt Flow Field resulted from a sustained and relatively low effusion eruption, creating a p & amacr;hoehoe flow field that continuously advanced across the landscape, utilising a drainage system that guided lava flow and helped to circumvent any topographic barriers

Phylum Cnidaria represents a unique group among venomous taxa, with its delivery system organised as individual organelles, known as nematocysts, heterogeneously distributed across morphological structures rather than packaged as a specialised organ. Acontia are packed with large nematocysts that are expelled from sea anemones during aggressive encounters with predatory species and are found in a limited number of species in the superfamily Metridioidea. Little is known about this specialised structure other than the commonly accepted hypothesis of its role in defence and a rudimentary understanding of its toxin content and activity. This study utilised previously published transcriptomic data and new proteomic analyses to expand this knowledge by identifying the venom profile of acontia in Calliactis polypus. Using mass spectrometry, we found limited toxin diversity in the proteome of acontia, with an abundance of a sodium channel toxin type I, and a novel toxin with two ShK-like domains. Additionally, genomic evidence suggests that the proposed novel toxin is ubiquitous across sea anemone lineages. Overall, the venom profile of acontia in Calliactis polypus and the novel toxin identified here provide the basis for future research to define the function of acontial toxins in sea anemones.

The Devonian represents a period of transition for the accretionary orogens of the Australian Tasmanides where the largest and inboard Thomson Orogen became stabilised and orogenic processes became focused in the outboard and newly developing New England Orogen. The end of tectonic activity in the Thomson and the adjacent Delamerian and Lachlan orogens culminated with the development of sev-eral overlying intracratonic sedimentary basins. We examine the two largest cover basins, the Adavale and Darling, using stratigraphic logging, sandstone petrography, detrital zircon and rutile U-Pb geochronology to fingerprint sediment sources to test whether the basins were once connected and part of a much larger cover basin system. Sediment provenance in the Adavale Basin is characterised by (i) continuous input from a basement-derived Ordovician (-480 Ma) igneous zircon source, (ii) reworking of metasedimentary basement rocks with a 'Pacific-Gondwana' age signature (iii) reworking of detrital rutile from Cambro-Ordovician sedimentary rocks in the Thomson Orogen ultimately sourced from the Musgrave Block and (iv) an addition of syn-depositional volcanic zircon from contemporary volcanism between-380 and 360 Ma. Sediment provenance of the Darling Basin is dominated by reworking of (meta)sedimentary basement, evident from large proportions of rounded zircons exhibiting a 'Pacific -Gondwana' age signature and detrital rutile with Peterman Orogeny ages. A much less significant age population of syn-depositional volcanic detrital zircons suggests input from contemporary volcanic sources which were more distal and extra-basinal.The comparison of sandstone compositions and detrital age information indicate both basins record similar provenance signals in terms of reworking of their respective hinterlands and receiving contribu-tions from relatively distal syn-depositional volcanism. However, the comparison of sediment prove-nance proxies, suggests that the Adavale and Darling basins were not connected during the Devonian and that the basins are intracratonic or cover basins, recording the stabilisation of the Thomson and Lachlan orogens, respectively.(c) 2023 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

The transition from the middle to late Permian (Guadalupian–Lopingian) is claimed to record one or more extinction events that rival the ‘Big Five’ in terms of depletion of biological diversity and reorganization of ecosystem structure. Yet many questions remain as to whether the events recorded in separate regions were synchronous, causally related, or were of a magnitude rivaling other major crises in Earth's history. In this paper, we survey some major unresolved issues related to the Guadalupian–Lopingian transition and offer a multidisciplinary approach to advance understanding of this under-appreciated biotic crisis by utilizing records in Southern Hemisphere high-palaeolatitude settings. We focus on the Bowen-Gunnedah-Sydney Basin System (BGSBS) as a prime site for analyses of biotic and physical environmental change at high palaeolatitudes in the middle and terminal Capitanian. Preliminary data suggest the likely position of the mid-Capitanian event is recorded in regressive deposits at the base of the Tomago Coal Measures (northern Sydney Basin) and around the contact between the Broughton Formation and the disconformably overlying Pheasants Nest Formation (southern Sydney Basin). Initial data suggest that the end-Capitanian event roughly correlates to the transgressive “Kulnura Marine Tongue” in the middle of the Tomago Coal Measures (northern Sydney Basin) and strata bearing dispersed, ice-rafted gravel in the Erins Vale Formation (southern Sydney Basin). Preliminary observations suggest that few plant genera or species disappeared in the transition from the Guadalupian to Lopingian, and the latter interval saw an increase in floristic diversity.

The Havre 2012 deep-sea rhyolite eruption went unobserved and was initially recognised from a massive pumice raft at the sea surface. Havre pumices are predominantly white or grey, however pink pumice is common in the raft. In subaerial explosive eruptions, pink pumice is understood to result from high-temperature atmospheric iron-oxidation. The presence of pink pumice questions the effusive eruption model for the Havre raft. Here we report results from X-ray Absorption Near Edge Structure spectroscopy, magnetic measurements, TEM imaging and glass chemistry that collectively show the colour results from increasing amounts of magnetite nanolites in the raft pumice glass oxidizing to hematite. This suggests a short-lived but powerful explosive eruption phase penetrated the water column allowing hot pyroclasts to oxidise in air. Our results therefore challenge the known depth limits for explosive eruptions in the marine realm and suggest pink pumice can be an indicator of magnetite nanolite-driven explosive eruptions.

The 2012 Havre submarine eruption produced a 1.5 km3 bulk rock volume or 0.52 km3 dense rock equivalent volume of rhyolite emplaced as minor lava flows, a field of sunken seafloor pumice, and a volumetrically dominant pumice raft. This moderately large volume of medium-K (1.4–1.6 wt% K2O) rhyolite pumice is relatively chemically homogeneous (71.5–73.0 wt% SiO2), and no trace element variation or cryptic zoning has been detected despite the textural diversity of pumice material. Radiogenic isotope ratios (87Sr/86Sr 0.703693–0.703744; 206Pb/204Pb 18.7648–18.7781; 208Pb/204Pb 38.587–38.605; 143Nd/144Nd 0.513001–0.513020) demonstrate the Havre rhyolite is sourced from mantle similar to regional eruptive products of the Kermadec arc volcanic front. Providing some further insight into the Havre magmatic system is an abundance of diverse volcanic rock fragments primarily embedded in the banded raft pumice. Embedded rock fragments represent a variety of fresh to hydrothermally altered lavas ranging in composition from basaltic to rhyolitic (50.6–72.3 wt% SiO2) and are likely sourced from varying depths within the volcanic conduit during explosive fragmentation. The diverse embedded volcanic rock fragments, therefore, represent earlier erupted lavas that constructed Havre volcano and are snapshots of the petrogenetic history of Havre. Magnesian augite in basaltic to basaltic andesite embedded rock fragments has a similar compositional range (En55Fs12Wo33 to En39Fs26Wo35) to the previously documented antecrystic clinopyroxene observed in the 2012 rhyolite pumice raft. Herein, we explain how this large volume of chemically homogeneous crystal-poor rhyolite can be generated in an oceanic arc setting based on major and trace element petrogenetic models. Rhyolite-MELTS crystal fractionation models indicate the antecrystic mineral compositions within the Havre pumice of plagioclase (An55–78), and magnesian augites (En53Fs10Wo37 to En40Fs26Wo34) are the primary phases that would crystallize in basaltic to andesitic melt compositions. Modeling indicates that the forerunner basaltic magma must be a relatively dry (∼1 wt% H20) low-K tholeiitic basalt in composition and would require ∼78% crystallization at different pressures to ultimately generate the Havre 2012 rhyolite.

Silicic volcanic and plutonic rocks (SiO 2 > 66 wt%) are generally viewed as being either compositional equivalents or complementary to each other. However, consideration of the geological, geophysical and chemical evidence suggests that silicic volcanic and plutonic rocks are not generally direct compositional equivalents. Also, volumetric and compositional relationships between the two groups suggest that silicic plutonic rocks are not generally cumulate mushes left behind after withdrawal of eruptible magma fractions. Reservoirs from which large-volumes of rhyolite have erupted should, in theory, contain residual, unevacuated magma fractions. However, the fine-grained and generally porphyritic rhyolites do not have the same compositions as the large volumes of silicic magmas that solidify to form batholiths. From these data we conclude that important genetic differences may exist in the modes of formation and evolution of silicic magmas that become rhyolites and those that become coarse-grained granitic rocks. In the second part of this study, we use phase-equilibrium and chemical modelling approaches to further investigate these preliminary conclusions. The aim is to shed light on the question of how the major classes of silicic magmas chemically evolve and whether there are fundamental differences between volcanic and plutonic silicic magmas.

Late’iki (previously known as Metis Shoal) is a highly active volcano in the Tofua arc with at least four temporary island-building eruptions and one submarine eruption in the last 55 years. The most recent eruption, commencing in October 2019, resulted in lava effusion and subsequent phreatic explosions, the construction of a short-lived island that was quickly eroded by wave action and possibly further phreatic activity that continued into January 2020. The two-pyroxene dacite from the 2019 eruption is similar to the 1967/8 eruptions suggesting the magma is residual from earlier eruptions and has not undergone further differentiation in the last 50 years. New observations of the 2019 eruption site confirm the lava-dominant character of the volcano summit but a thin veneer of wave-reworked, finely fragmented lava material remains that is interpreted to have been produced by phreatic explosions from hot rock-water interactions during the effusive eruption. A notable absence of quench-fragmented hyaloclastite breccias suggests that non-explosive quench fragmentation processes were minimal at these shallow depths or that hyaloclastite debris has resedimented to greater depths beyond our summit survey area.

Thermodynamic modelling shows that, although high-silica rhyolitic melts can form through fractionation of low-silica rhyolitic magmas the complementary cumulates do not have compositions similar to natural plutonic granites. Rather than being granitic, the predicted cumulates would be monzonitic to granodioritic. Thus, it is unlikely that the majority of monzogranitic to syenogranitic batholiths formed in this way and although many high-silica rhyolites may be cogenetic with plutonic rocks, they seem to be magmatically decoupled from most accompanying plutonic masses. We suggest that mush heating may not be the major cause of apparent resorption textures in phenocrysts and antecrysts in rhyolitic magmas. A significant cause is simple magma ascent under near-isothermal conditions, and embayments in quartz seem to be growth rather than resorption features. Thus, the presence of ‘resorption’ textures should not be regarded as firm evidence for mush heating and remobilisation. Although some glomerocrysts may have been harvested from mush environments, the modelled melt temperatures, compositions and the near-liquidus mineral assemblages are generally incompatible with such an origin. Many petrogenetic puzzles surrounding silicic magma systems stem from an assumption that there is a close magmatic connection between silicic volcanic rocks and granitic plutons, and because of a model that assumes the existence of large, shallow magma reservoirs in which fractionation and crustal assimilation occur. Models predicated on the concept of mush rheological lock-up, mush reactivation and melt extraction from mushes to form eruptible rhyolitic liquids should be re-evaluated. In general, silicic plutonic rocks are neither compositional equivalents nor cumulate complements of silicic volcanic rocks.

Backarc basin systems are important sites of extension leading to crustal rupture where basin development typically occurs in rifting phases (or stages) with the final successful stages identified by the formation of spreading ridges and new oceanic crust. The East Manus Basin is a young (<1 Ma), active, rapidly rifting backarc basin in a complex tectonic setting at the confluence of the oblique convergence of the Australian and Pacific plates. Here we undertake the first comprehensive spatial-temporal morphotectonic description and interpretation of the East Manus Basin including a link to the timing of, and tectonic controls on, the formation of seafloor massive sulfide mineralization. Key seafloor datasets used in the morphotectonic analysis include multi-resolution multibeam echosounder seafloor data and derivatives. Morphotectonic analysis of these data defines three evolutionary phases for the East Manus Basin. Each phase is distinguished by a variation in seafloor characteristics, volcano morphology and structural features: Phase 1 is a period of incipient extension of existing arc crust with intermediate to silicic volcanism; Phase 2 evolves to crustal rifting with effusive, flat top volcanoes with fissures; and Phase 3 is a nascent organized half-graben system with axial volcanism and seafloor spreading. The morphotectonic analysis, combined with available age constraints, shows that crustal rupture can occur rapidly (within ∼1 Myr) in backarc basins but that the different rift phases can become abandoned and preserved on the seafloor as the locus of extension and magmatism migrates to focus on the ultimate zone(s) of crustal rupture. Consequently, the spatial-temporal occurrence of significant Cu-rich seafloor massive sulfide mineralization can be constrained to the transition from Phase 1 to Phase 2 within the East Manus Basin. Mineralizing hydrothermal systems have utilized interconnected structural zones developed during these phases. This research improves our understanding of the early evolution of modern backarc systems, including the association between basin evolution and spatial-temporal formation of seafloor massive sulfide deposits, and provides key morphotectonic relationships that can be used to help interpret the evolution of paleo/fossilized backarc basins found in fold belts and accreted terrains around the world.

Silicic magmatism is a feature of all continental LIP events, and where volumetrically significant, occurs as high‐frequency (~1,000–10,000 yr recurrence intervals), large‐magnitude (>M8) explosive supereruptions producing vast ignimbrite sheets. Silicic supereruptions inherently have the eruptive mechanism to deliver aerosols and ash to the stratosphere for global dispersal, and thus overcome eruptive barriers that exist for flood basalts built up by long‐lived, low effusion and low vigor fountains that lack height and persistent stratospheric penetration. The historical record demonstrates the climate forcing capabilities of silicic supereruptions, which during LIP events, were likely associated with large CO2, SO2, halogen, and Hg emissions, and through tephra deposition, could cause iron fertilization in the world's oceans, thereby kick‐starting phytoplanktonic biological pumps to significantly draw down atmospheric CO2. What may be important, therefore, for LIP events to cause the most environmental impact and trigger a mass extinction, is the combined effect of closely spaced basaltic and silicic, or effusive and explosive, eruptions that work in tandem to overload the troposphere and stratosphere with volcanic aerosols producing rapid decadal‐scale, extreme fluctuations in pH driven by acid rain, S‐, or iron fertilization‐driven temperature chills, and toxic UV radiation bursts. These effects could be repeated within as little as a few hundred years of each other particularly during hyperactive LIP pulses.

Food deprivation may decrease selectivity in food; however, (1) whether animals can cross a selectivity threshold whereby they ingest non-nutritive items ('non-food') in lieu of food (engaging in pica/lithophagia), (2) their behaviour, or (3) the implications of these behaviours are not documented. By examining carcasses of seabirds that ingested pumice of known provenance prior to death, we provide insights into whether wild animals starve because they have eaten non-food, or whether they eat non-food because they are starving. We investigated ingestion of pumice and plastic in carcasses of short-tailed shearwaters Ardenna tenuirostris following a significant starvation mortality event (also known as seabird wreck), during which millions of shearwaters died along the eastern Australian coastline in 2013. We found that the stomachs of 96.5% of 172 seabirds sampled contained pumice or plastic at the time of death. We used global location sensors to track the 2013 shearwater migration and overlaid these tracks with the dispersing pumice raft from the 2012 Havre underwater volcanic eruption, Kermadec Islands, New Zealand. We determined that shearwaters in a starved state had ingested pumice 12-41 h before death, indicating that starving or food-stressed seabirds exhibit reduced prey discrimination. The provenance of the ingested plastic was not known. Ingestion of non-nutritive items has serious implications for wildlife, particularly long-lived or migrating species. Additional risk to already nutritionally compromised animals includes dietary dilution, gastric foreign body obstruction and toxicity. With a projected changing climate and increased marine pollution and over-exploitation of resources, this study has implications for the interaction of stressors, mass mortalities and exacerbation of existing threats to marine species.

Coral reef ecosystems are under increasing pressure from local and regional stressors and a changing climate. Current management focuses on reducing stressors to allow for natural recovery, but in many areas where coral reefs are damaged, natural recovery can be restricted, delayed or interrupted because of unstable, unconsolidated coral fragments, or rubble. Rubble fields are a natural component of coral reefs, but repeated or high-magnitude disturbances can prevent natural cementation and consolidation processes, so that coral recruits fail to survive. A suite of interventions have been used to target this issue globally, such as using mesh to stabilise rubble, removing the rubble to reveal hard substrate and deploying rocks or other hard substrates over the rubble to facilitate recruit survival. Small, modular structures can be used at multiple scales, with or without attached coral fragments, to create structural complexity and settlement surfaces. However, these can introduce foreign materials to the reef, and a limited understanding of natural recovery processes exists for the potential of this type of active intervention to successfully restore local coral reef structure. This review synthesises available knowledge about the ecological role of coral rubble, natural coral recolonisation and recovery rates and the potential benefits and risks associated with active interventions in this rapidly evolving field. Fundamental knowledge gaps include baseline levels of rubble, the structural complexity of reef habitats in space and time, natural rubble consolidation processes and the risks associated with each intervention method. Any restoration intervention needs to be underpinned by risk assessment, and the decision to repair rubble fields must arise from an understanding of when and where unconsolidated substrate and lack of structure impair natural reef recovery and ecological function. Monitoring is necessary to ascertain the success or failure of the intervention and impacts of potential risks, but there is a strong need to specify desired outcomes, the spatial and temporal context and indicators to be measured. With a focus on the Great Barrier Reef, we synthesise the techniques, successes and failures associated with rubble stabilisation and the use of small structures, review monitoring methods and indicators, and provide recommendations to ensure that we learn from past projects.

The generation of continental crust, its bulk composition and temporal evolution provide important records of plate tectonics and associated magma generating processes. However, the long-term integrated effects of repeated magmatic events on crustal growth, composition and differentiation and therefore, on crustal evolution are rarely considered. Here, we examine long-term (~350 Myr) temporal compositional trends of granitic magmatism within a limited (~200 x 100 km) area in the Northern New England Orogen of Queensland, Australia to avoid lateral crustal variations in order to understand how temporal compositional variations of silicic igneous rocks record crustal evolution. Long-term temporal compositional variations are tracked using whole-rock chemistry, zircon chronochemistry and zircon Hf isotopic compositions. We particularly focus on whole-rock U, Th and K abundances and calculated heat production values as proxies for crustal evolution, and tracking crustal sources involved in granitic magmatism. We identified two major compositional groupings within the study area that were repeatedly produced over time: Compositional Group 1 comprises voluminous I-type igneous rocks emplaced during the Permo-Carboniferous and Early Cretaceous; and Group 2 represents mainly lower volume A-type igneous rocks of Triassic, Middle Cretaceous and Tertiary age. Importantly, these compositional groupings alternate over the 350 Myr history of granitic magmatism within the study area. Heat production values over time exhibit a zig-zag pattern and mirror zircon Hf isotopic signatures where rocks with elevated heat production values exhibit unradiogenic (crustal) Hf isotopic compositions. We identify the composition of crustal sources, level of the crust undergoing partial melting, scale of magmatism and source crustal volume as important factors in understanding the compositional diversity of silicic igneous rocks. We interpret the two chemical groupings to reflect the following magma generating conditions: Group 1 igneous rocks record large-scale magmatic systems triggered by extensive crustal melting of multiple lower to middle crustal sources which produce more compositionally and isotopically uniform magma compositions that approach bulk crustal compositions. In contrast, Group 2 igneous rocks reflect smaller-scale magmatic systems generated from smaller scale partial melting events of the middle to upper crust that produced A-type magmas. Over the long-term, the successive large-scale magmatic events (recorded by Group 1 igneous rocks) through their concomitant basaltic underplating make the Hf composition of the lower crust more radiogenic, and tend to homogenise the isotopic composition of the continental crust. We consider three important coupled controls: 1) large-scale magmatic systems promote extensive crustal melting potentially blending multiple crustal sources that can also include a significant juvenile source contribution; 2) melt depletion whereby older, and potentially more unradiogenic crustal materials become more refractory; and 3) “crustal jacking” where mantle-derived magmas are added as underplate to the crust (i.e. basification) and can shift older crustal materials to more shallow levels (potentially in concert with erosion and exhumation) and away from zones of crustal melting. Our findings highlight the importance of integrating the geologic and intrusive history with whole-rock geochemical data and isotopic information, and have direct implications for continental regions that exhibit protracted igneous histories and where isotopic compositions may trend towards more juvenile compositions such as circum-Pacific or retreating accretionary orogens.

Determining the oxidation state of Fe through parameterization of X-ray absorption near-edge structure (XANES) spectral features is highly dependent on accurate and repeatable energy calibration between spectra. Small errors in energy calibration can lead to vastly different interpretations. While simultaneous measurement of a reference foil is often undertaken on X-ray spectroscopy beamlines, other beamlines measure XANES spectra without a reference foil and therefore lack a method for correcting energy drift. Here a method is proposed that combines two measures of Fe oxidation state taken from different parts of the spectrum to iteratively correct for an unknown energy offset between spectra, showing successful iterative self-calibration not only during individual beam time but also across different beamlines.

In the paper by Jones et al. (2020), the authors have noted that an incorrect value was published for the calibrated Fe3+/Fe for the rafted pumice sample from the 2012 Havre eruption. The correct value is 0.257 (0.010) and is included in the updated Table 2 below and updated in the inset in Fig. 3(c) (overleaf). (Table Presented).