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The Minas-Bahia orogeny juxtaposed Archean crustal fragments and Paleoproterozoic magmatic arcs to form the Sao Francisco-Congo Paleocontinent by the Rhyacian (ca. 2.05 Ga). Unravelling the Minas segment of the Minas-Bahia Orogenic Belt (MBO) is an important key to understanding the role of the Sao Francisco-Congo Paleocontinent in the construction of the Columbia Supercontinent. The Orosirian (ca. 1.9 Ga) final amalgamation of Columbia was preceded by a complex history of accretion of Archean nuclei and Proterozoic magmatic arcs. We present new whole-rock element geochemistry and isotopic (Rb-Sr, Sm-Nd) data and U-Pb ages for granitoid rocks of the main basement complexes located in the southern part of the Sao Francisco cratonic tip, which displays varied degrees of Neoproterozoic reworking related to the Brasiliano orogeny. Published data for the Campo Belo Complex, the Mineiro Belt and the Piedade Block are combined with the new data set to propose an integrated model for the tectonic evolution of the Minas segment of the MBO. This evolutionary model documents a complete Paleoproterozoic orogenic cycle, from subduction with terrane accretion to collision, followed by late-orogenic collapse. Subduction started diachronously between ca. 2.4 Ga and 2.2 Ga involving various Archean nuclei and Paleoproterozoic magmatic arcs that were later amalgamated during two collisional events at ca. 2.10 and 2.05 Ga. The oldest tonalite-trondhjemite-granodiorite (TTG) to sanukitoid magmatic suites transition are of Neoarchean age in the Piedade block, and of Paleoproterozoic age in the Mineiro belt and Mantiqueira complex, apparently indicating a diachronous onset of plate tectonic processes in different crustal segments. The petrogenesis, geochronology and isotopic signatures of these granitoid rocks provide important evidence towards understanding the periodicity of tectonic processes associated with the supercontinent cycle throughout Earth history.

Granitoid batholiths dominated by felsic to intermediate compositions are commonly associated with mafic plutons and enclaves; however, the genetic relationship between the apparently coeval but compositionally dissimilar magmas is unclear. Here, we reviewed the age and lithogeochemical and Nd-Sr isotopic compositions of some classic plutonic rocks emplaced in the Northern Highlands, Grampian and Connemara terranes of the Caledonide orogen of Scotland and Ireland. The Northern Highlands terrane consists mostly of Neoproterozoic metasedimentary rocks of the Moine Supergroup and is located north of the Great Glen fault. The Grampian terrane also consists of Neoproterozoic metasedimentary rocks (Dalradian Supergroup) and is located south of the Great Glen fault in both Scotland and Ireland. Amphibolite-facies metasedimentary rocks in the Connemara terrane are correlated with the Dalradian Supergroup, and the terrane is bounded by splays of the Highland Boundary and Southern Uplands faults. These three terranes were intruded by Silurian–Devonian mafic and felsic to intermediate plutonic rocks that display field evidence for mingling and mixing and have a similar range (between ca. 437 and 370 Ma) in emplacement ages. This range implies they were intruded during and after the late Caledonian Scandian orogenic event that resulted from the mid- to late Silurian collision of amalgamated Avalonia and Baltica with Laurentia and the final closure of the Iapetus Ocean. Our review supports the contention that the Great Glen fault represents a major compositional boundary in the Silurian lithosphere. Felsic to intermediate plutons that occur north of the Great Glen fault are more enriched in light rare earth elements and Ba-Sr-K compared to those to the south. Isotopic compositions of these late Caledonian plutonic rocks on both sides of the Great Glen fault indicate that metasomatism and enrichment of the subcontinental lithospheric mantle beneath the Northern Highlands terrane occurred just prior to emplacement of late Caledonian plutons. Within the same terrane, mafic and felsic to intermediate rocks display similar trace-element and rare earth element concentrations compatible with models implying that fractionation of a mafic magma played an important role in generating the felsic to intermediate magmas. The onset of slab failure magmatism may have been diachronous along the length of the collision zone. If so, slab failure may have propagated laterally, possibly initiating where promontories collided.

The southern portion of the Sao Francisco Palaeocontinent in Brazil is denoted by Archean nuclei and Paleoproterozoic magmatic arcs that were amalgamated during Siderian to Orosirian orogenic processes (ca. 2.4–2.1 ​Ga). New isotopic U–Pb in zircon and Sm–Nd whole rock combined with major and trace element composition analyses constrain the crystallization history of the Neoarchean Piedade block (at ca. 2.6 ​Ga) and the Paleoproterozoic Mantiqueira Complex (ca. 2.1–1.9 ​Ga). These therefore display quite different magmatic histories prior to their amalgamation at ca. 2.05 ​Ga. Sm–Nd and Rb–Sr isotopes imply a mixed mantle-crustal origin for the samples in both units. A complete Palaeoproterozoic orogenic cycle, from subduction to collision and collapse, is recorded in the Piedade Block and the Mantiqueira Complex. Rhyacian to Orosirian subduction processes (ca. 2.2–2.1 ​Ga) led to the generation of coeval (ca. 2.16 ​Ga) TTG suites and sanukitoids, followed by late (2.10–2.02 ​Ga) high-K granitoids that mark the collisional stage. The collisional accretion of the Mantiqueira Complex against the Piedade Block at 2.08–2.04 ​Ga is also recorded by granulite facies metamorphism in the latter terrane, along the Ponte Nova suture zone. The collisional stage was closely followed by the emplacement of within-plate tholeiites at ca. 2.04 ​Ga and by alkaline rocks (syenites and enriched basic rocks) at ca. 1.98 ​Ga, marking the transition to an extensional tectonic regime. The discovery of two episodes of TTG and sanukitoid magmatism, one during the Neoarchean in the Piedade Complex and another during the Rhyacian in the Mantiqueira Complex, indicates that the onset of subduction-related melting of metasomatized mantle was not restricted to Neoarchean times, as generally believed, but persisted much later into the Paleoproterozoic.

Modern continental crust has evolved to a more potassic, granitic composition than early continental crust, which comprises largely sodic TTG-suite magmas. The present paradigm holds that the latter are largely “juvenile” (in the sense that the time from mantle extraction to felsic crust production is comparatively short, of the order 10–100 Ma) while the former represent recycled older crust of igneous or sedimentary composition. The data from high-Mg diorites, tonalites, granodiorites and potassic granites of the 125–115 Ma Menglian Batholith (SE Tibet) exemplify the modern situation and can therefore be used to constrain current crust formation processes. These rocks have higher concentrations of incompatible elements than magmatic rocks from typical continental arc settings, with a continuum of increasing K2O/Na2O ratios, SiO2, K2O, Rb, and Th concentrations juxtaposed with decreasing MgO, CaO, and Sr. They consistently record both higher zircon δ18O values than mantle values and decoupled Ndsingle bondHf isotope systems caused by the interaction of subducted sediments with the mantle wedge. Petrogenetic mechanisms that connect the suite include crystal fractionation within the diorites, melting of the lower crust induced by advection of heat and water by the diorites, and high-level fractionation of the tonalite-granodiorite suite to produce the high-silica granites. Therefore, this example of modern fertile continental crust had a five-stage evolution: (1) subduction-enrichment of the mantle source, (2) mantle melting to produce mafic magmas that pooled in or below the lower crust, (3) mafic magma differentiation to produce the tonalite-granodioritic magmas controlled by crystal-liquid equilibria, (4) crustal melting and admixture to the evolving felsic magmas and (5) final high-level fractionation and melt extraction to produce the silicic extreme, enriched in incompatible elements such as Rb, Th and K. This model could be a general mechanism for how modern mature continental crust evolves. Importantly, it indicates a significant role for mafic magmas and thence a more important role for juvenile additions than is generally accepted.

International audience; Crustal evolution is currently governed by plate tectonics and it has been shown that between the Archean and the Phanerozoic major changes in subduction styles occured. Among others, the chemistry of different plutonic rocks through time and the understanding of their petrogeneses have helped to define different stages in the evolution of plate tectonics. An important change around 2.7 Ga led to the formation of magmas within a metasomatized mantle: the sanukitoids. This diachronous event is interpreted as the result of the evolution from a shallow to a steep subduction style. Similar rocks are generated in the modern Earth, for example the Caledonian (Palaeozoic) high Ba-Sr plutons in northern Scotland [1].In this contribution, we aim to study this Caledonian sanukitoid-like suite and test the reliability of several isotopic systems within the abundant accessory minerals. Whole rock chemistry (including radiogenic and stable isotopes) is well constrained. We now present a multi-isotope study of three accessory minerals (titanite, zircon and apatite). New Sm-Nd in-situ isotopes in titanite and apatite and Hf in zircon results are discussed in the light of oxygen isotopes previously published on the same samples for all phases [2]. These data are then compared to previous WR data obtained on the same samples[3], [4].[1] M. Fowler & H. Rollinson (2012) Geology 40, 1079–1082.[2] E. Bruand et al. (2019) Geochim. Cosmochim. Acta 255, 144–162.[3] M. Fowler et al. (2001) J. Geol. Soc. London., 158, 521–534.[4] M. Fowler et al. (2008) Lithos 105, 129–148.

Winter Heliotrope (Petasites pyrenaicus, previously P. fragrans), is a persistent, rhizome-forming species found throughout the Mediterranean region and North Africa and is an Invasive Alien Plant (IAP) in the UK and Ireland. P. pyrenaicus excludes native flora by forming a dense, compact canopy that persists for much of the growing season, and is often found growing in rough ground, riparian areas and along communication routes, incurring significant management costs at sites of conservation interest. Our study describes the first field-based assessment of P. pyrenaicus control treatments, testing 12 physical and/or chemical treatments in replicated 1 m2 plots over four years and one chemical treatment over three years. Treatments focused on understanding phenology and resource allocation to exploit rhizome source-sink relationships in P. pyrenaicus. Multiple-stage glyphosate- and picloram-based treatments reduced leaf canopy cover to zero (%) over time, though no treatment completely eradicated P. pyrenaicus. When designing management strategies, effective P. pyrenaicus control may be achieved by a single annual soil and/or foliar application of picloram at 1.34 kg AE ha-1 in spring, or by a single annual foliar application of glyphosate in spring at 2.16 kg AE ha-1. Control is not improved by the addition of other herbicides or physical treatment methods, underlining the importance of these herbicides for perennial invasive plant management. This work confirms the importance of considering plant phenology, resource allocation and rhizome source-sink relationships, to increase treatment efficacy and reduce the environmental impacts associated with the management of P. pyrenaicus and other invasive, rhizome forming species.

High-K calc-alkaline to shoshonitic suites are widespread and generally volumetrically small but provide key information on magmatic mantle-crust interactions. Limited work has addressed the multi-stage formation of relatively high-volume high-K to shoshonitic rocks. A newly identified, Late-Cretaceous to Early-Cenozoic high-volume high-K to shoshonitic association (ca. 28,000 km3) is described, from the southeastern Himalayan–Tibetan orogen. The mafic intrusions are shoshonitic (K2O contents, ~ 3.3 wt.%), have high-Mg contents (~ 5.1 wt.%) with high-Mg# (57), LREE and LILEs with low Ba/Th, Ba/La, Sm/La ( 0.70), Th/Yb, Th/La (> 0.2) and La/Sm, and lack an Eu anomaly. Their mafic minerals are hydrous, dominated by magnesio-hornblende (Mg#, ~ 0.69–0.73) and Mg- and K-biotite (MgO, 7.27–9.26 wt.%; K2O, 9.65–10.1 wt.%). Such characteristics strongly suggest derivation from the sub-continental lithospheric mantle (SCLM), metasomatized by sediment-derived melts/fluids. The associated felsic intrusions have high SiO2, alkali content (Na2O + K2O contents up to 10.0 wt.%) and incompatible elements (e.g., K, Rb), with ferropargasite-hastingsite and ferrobiotite-siderophyllite as the mafic phases. These characteristics point to derivation from the continental crust enriched by fluids, likely those released from the contemporaneous mafic magmas crystallising at depth. In contrast to low-volume potassic magmatism from post-collision and earliest arc-rift settings, these high-volume high-K and shoshonitic intrusions define a mantle-to-upper crust pathway at an active continental margin. Alongside geophysical data, these observations are consistent with the contemporary subduction history, arising from subduction of the Neo-Tethyan ocean slab to initial collision of India-Asia, from steepening subduction to slab rollback and breakoff.

Co-auteur étranger; International audience; Oxygen isotope analysis of zircon, often combined with geochronology and Hf isotope analysis, has been pivotal in understanding the evolution of continental crust. In this contribution, we expand the use of underexplored accessory phases (titanite and apatite) by demonstrating that their oxygen isotope systems can be robust, and by developing geochemical indicators involving O isotopes and trace element concentrations to better constrain magma petrogenesis. These minerals have the advantage over zircon of being present in less evolved magmas and being more responsive to igneous processes and crustal metamorphism. We present new data on titanite, apatite and zircon from carefully-selected granitoids through geological time: the Phanerozoic high Ba-Sr granites (Caledonian province, Scotland), Archean sanukitoids (Karelia province, Finland) and a Neoproterozoic basalt-andesite-dacite-rhyolite suite (BADR; Guernsey, Channel Island). We demonstrate: (i) that d 18 O values of the studied accessory minerals are not affected by crystal fractionation, (ii) a strong correlation between d 18 O in all three accessory minerals, showing that apatite and titanite can faithfully record the magmatic d 18 O; (iii) that these accessory minerals can also record metamorphic and/or fluid circulation events during the syn-to post-magmatic history of granitoids.

A zircon Hf isotope data set from Archean and Paleoproterozoic magmatic and metasedimentary rocks of the southern São Francisco craton (Brazil) is interpreted as evidence of accretionary and collisional plate tectonics since at least the Archean-Proterozoic boundary. During the Phanerozoic, accretionary and collisional orogenies are considered the end members of different plate tectonic settings, both involving preexisting stable continental lithosphere and consumption of oceanic crust. However, mechanisms for the formation of continental crust during the Archean and Paleoproterozoic are still debated, with the addition of magmatic rocks to the crust being explained by different geodynamic models. Hf isotopes can be used to quantify the proportion of magmatic addition into the crust: positive εHf values are usually interpreted as indications of magmatic input from the mantle, whereas crust-derived rocks show more negative εHf. We show that the crust of the amalgamated Paleoproterozoic tectonostratigraphic terranes that make up the southern São Francisco craton were generated from different proportions of mantle and crustal isotopic reservoirs. Plate tectonic processes are implied by a consistent sequence of events involving (1) the generation of juvenile subduction-related magmatic arc rocks, followed by (2) collisional orogenesis and remelting of older crust, and (3) post-collisional bimodal magmatism.

Modern style plate tectonics is characterized by one-sided subduction and continental margin basalt-andesite-dacite-rhyolite (BADR) magmatism, whereas continental magmatic rocks in the Archaean record had tonalite-trondjhemite-granodiorite (TTG) composition. Their main difference is the absence (in the modern style) and the presence (in the ancient style) of abundant juvenile, basalt-derived felsic magmatism. The diversity of modern continental magmas depends partly on metasomatic processes in the mantle wedge providing sediment input (melt/fluid). Contrasting scenarios in the rock record therefore are the presence or absence of (1) basalt-derived melt (TTG) and (2) sedimentary input to the magmas. A late, “Archaean-style” tectonic regime is recorded in the Palaeoproterozoic Mineiro Belt (Brazil) using whole-rock geochemistry of its plutons coupled to zircon Hf and O isotopes from these rocks and from detrital grains from the local (meta)sediments. Increasing δ 18 O with decreasing eHf(t) values in zircon indicate oceanic crust recycling and input of sediments to the mantle wedge during the Palaeoproterozoic. Since some form of early subduction including the formation of a mantle wedge has occurred since the Mesoarchaean, it seems that the onset of subduction and the final establishment of modern plate tectonics at the global scale are temporally distinct. The latter did not occur until the Palaeoproterozoic. Prior to this time (“ante-plate tectonics”), punctuated subcretion/subduction marks a gestational stage that took c. 800 Myr to transition diachronously to a truly global mechanism. The TTG-sanukitoid transition, which signals the opening of a mantle wedge, occurred in the Mineiro Belt during the early Proterozoic “magmatic lull” and thus represents the last gasp of the ante-plate tectonics regime.

Urban air quality is considered a major issue in cities worldwide, with particulate matter (PM) recognised as one of the most harmful pollutants regarding human health. The use of plants to act as air filters and immobilise PM has been identified as a potential method to improve the air quality in these areas. The majority of the work has focused on trees, with the application of shrub and herbaceous species largely overlooked. Two contrasting leaf morphologies from a shrub and herbaceous plant species were sampled at four locations across Southampton (UK), from varying traffic conditions. Samples were analysed for the mass of PM captured, particle size, and elemental composition. These analyses were used to characterise the different sites and the plants&rsquo, effectiveness at immobilisation of PM. Captured PM mass was shown to be directly related to traffic density, with greater traffic density leading to higher levels of captured PM. PM origins were attributed to emissions from vehicles and the resuspension of particles by vehicle movement. The bulk of the PM mass was shown to originate from natural, crustal sources including large proportions of Al, Si, and/or Ca. Increases in elements from anthropogenic enhancement (such as Fe and Zn) were related to high traffic density. Particle size analysis identified that, despite the use of standard leaf-washing protocols with a final 2.5 &micro, m filter, PM was dominated by fine particles (&lt, 2.5 &micro, m physical diameter), with particles &gt, 10 &micro, m rare. Bramble leaves were calculated to have a species-specific deposition velocity 0.51 cm s&minus, 1 greater than ivy, with deposition velocities calculated at 1.8 and 1.3 cm s&minus, 1 for ivy and 2.3 and 1.8 cm s&minus, 1 for bramble at Redbridge Road and Brinton&rsquo, s Road, respectively. These values can allow for the more accurate modelling and estimation of the PM removal abilities of these plants.

Numerous studies have identified the issue of road surface runoff as a source of contamination into waterways but the impact of vehicular wash-off is less well understood. A ford crossing provides a pathway for vehicle-derived contaminants emanating from both road surface runoff and vehicular wash-off into a river system. Twyford Lane Ford (Ford 1) and Birchgrove Lane Ford (Ford 2), located ca. 600 m apart on a tributary of the River Ouse in Sussex (UK), were the focus of this study. A combination of biomonitoring (assessment of benthic macroinvertebrates) and chemical assessments of water and sediments has been undertaken to determine any detrimental impacts, such as a lack in biodiversity, resulting from the ford crossings. Sediment concentrations of chromium (Cr3+), lead (Pb) and zinc (Zn) were generally elevated at Ford 1, attenuating at sampling points between the fords to then peak at Ford 2. However, sediment particle size was seen to have an influence on elemental concentrations. In general, an increase in elemental concentrations was associated with a higher percentage of fine-grained sediments (≤63 μm). Elevated concentrations of Zn and magnesium (Mg) were identified within water samples taken during a precipitation event following a prolonged dry period. The biomonitoring results found reduced BMWP (Biological Monitoring Working Party) scores at positions close to the ford crossings, and where the stream was in proximity to the roadside. Sensitive Ephemeroptera were largely absent at sampling points closest to the fords, which is likely to be associated with elevated Zn. The results suggest that careful consideration should be applied when selecting crossing points over sensitive waters.

Delineating the evolution of the Earth’s dynamics and interactions between its different silicate reservoirs (ocean crust, continental crust, mantle) is key to understanding planetary differentiation and the conditions of surface habitability. Today, plate tectonic processes play a major role in creating and destroying the Earth’s crust, and modifying its silicate mantle. For this reason the Earth is unique in the solar system. Reconstructing its long-term evolution is, however, extremely difficult since the Hadean record is essentially missing and most Archean rocks have experienced reworking and overprinting of their original signatures. In this presentation, we will explore the constraints available with isotopic and chemical information from REE-bearing minerals in magmas that appear at different times during Earth history. We present, new geochemical data on these phases from a compilation of granitoids that cover a large span of the geological record from the Archean to the Phanerozoic. We demonstrate that trace element analysis and detailed petrographic work can give direct information about the petrogenesis of the host magmas even when these granitoids have been affected by metamorphism. Other studies focusing on rutile have shown that it records important information on metamorphic conditions in the Archean. On the other hand, and also helpfully, all three minerals are resistant to secondary processes and erosion, and thus may also offer significant archives of pertinent information in the detrital rock record. Development of such petro-geochemical tools could deliver complementary information to that provided by zircon and have significant potential for provenance studies and for tracing the secular evolution of the Earth.

International audience; doi: 10.7185/geochemlet.2006 Underexplored accessory minerals such as titanite and apatite have the potential to give insights into the nature and the petrogenesis of their host rock. Their trace element and REE-rich compositions carry a record of crystallisation history and chemical characteristics of their source. Moreover, titanite and, to a certain extent, apatite are resistant to erosion during sedimentary cycles which makes them ideal to reconstruct the history of long-eroded continental land-masses. Here we report new trace element data on apatite and titanite from granitoids of different Archean cratons and comparative granitoids from the Phanerozoic. Trace element signatures of both minerals reveal systematic chemical trends in Y, LREE and Sr contents related to the nature of their host magma, which are used to construct discrimination diagrams delineating Archean TTGs from sanukitoids, and modern adakites from S/I-type granites. By comparing Archean granitoids (TTG and sanukitoids) and their Phanerozoic counterparts (adakite and high Ba-Sr granites), we show that the robust nature of these phases makes them reliable recorders of petrogenetic information from Archean rocks, that usually have been affected by secondary processes (meta-morphism, deformation, hydrothermal activity). Applied to the rock record, both phases potentially provide detailed archives of magmatic evolution through time.

Accurately constraining local variation in tidal water levels is the vital first step in managing the risk of coastal hazards associated with sea level rise (SLR). Here we show sub-regional patterns in delta tidal dynamics and coastal SLR along the northern Bay of Bengal based on long-term (1990 to 2017) in-situ measurement data. Seasonal trend decomposition combined with robust linear modelling are applied to determine rates of water level change, with an average rise in coastal extreme sea levels of 6.9 ± 2.1 mm yr−1 translating to increases of 5.1 ± 4.2 mm yr−1 in tidal water levels within the delta. Mean increases of 18.3 ± 4.1 mm yr−1 and 18.2 ± 6.8 mm yr−1 at high and low-tide respectively in tidally dominated rivers of southwest Bangladesh contrast with the fluvially active central and eastern sections of the delta where falling trends of −6.5 ± 2.3 mm yr−1 (high-tide) and −10.2 ± 3.1 mm yr−1 (low-tide) are recorded. Rapid changes in river level at individual sites can occur over periods of ca. 3 to 10 years, most likely resulting from short-term hydro-morphological changes. An acceleration of change in high-tides is indicated by a rise from the long term (1950 to 2018) rate of 4.4 ± 1.5 mm yr−1 to 5.9 ± 3.2 mm yr−1 between 1990 and 2017, leading to increased risk for the local population. At local and regional scales, the upstream impact of SLR within the delta is observed to be strongly modulated, necessitating more detailed analysis of driving mechanisms at the site specific level. Our results can be used to aid development of adaptation strategies in Bangladesh and as a call for increased monitoring of hydro-morphological parameters within the Bengal delta and other large deltas in Asia and worldwide.

Ni in PM10 can contribute to health problems such as cardiovascular mortality at low ambient concentrations, and in the UK is measured through the Heavy Metals Network. Localised concentrations of nickel in PM10 have resulted in a Sheffield air quality monitoring station exceeding the EU target value of 20 ng/m3. Two localised sources of nickel have been identified; one relating to point source emissions, and one relating to fugitive dust emissions. Fugitive dust emissions from a Sheffield steelworks have therefore been assessed using a novel approach, with six months of sticky pad and PM10 dust monitoring, and subsequent elemental characterisation of dust and control samples using ICP-OES and ICP-MS used to inform dust dispersion modelling. Three new fugitive dust source areas on-site were identified from the dust monitoring and characterisation results. Emission rates of Ni were estimated from each source, with adjustments made based on the dust monitoring and characterisation results. Dispersion modelling was undertaken using the new and existing Ni dust sources and results compared favourably to previous studies. Source apportionment of measured concentrations was investigated with regard to the modelling and characterisation results and showed that on-site fugitive dust sources were not significantly different to a fugitive nickel source identified in previous research. However, both source apportionment results and dust monitoring results show that Ni concentrations at the local monitoring station were not increased when fugitive emissions from the study site were highest, or when the winds from the direction of the site were most frequent, indicating that fugitive dust emissions that caused increased concentrations throughout this study period were derived from sources in the area other than the study site.

Uranium-lead (U-Pb) zircon dating establishes a late Cambrian (Drumian) protolith age of 503 ± 2 Ma for a trondhjemitic gneiss of the calc-alkaline Strathy Complex, northern Scottish Caledonides. Positive εHf and εNd values from trondhjemitic gneisses and co-magmatic amphibolites, respectively, and an absence of any inheritance in zircon populations support published geochemistry that indicates a juvenile origin distal from Laurentia. In order to account for its present location within a stack of Laurentia-derived thrust sheets, we interpret the complex as allochthonous and located along a buried suture. We propose that a microcontinental ribbon was detached from Laurentia during late Neoproterozoic to Cambrian rifting; the intervening oceanic tract closed by subduction during the late Cambrian and formed a juvenile arc, the protolith of the Strathy Complex. The microcontinental ribbon was reattached to Laurentia during the Grampian orogeny, which transported the Strathy Complex as a tectonic slice within a nappe stack. Peak metamorphic conditions for the Strathy Complex arc (650–700 °C, 0.6–0.75 GPa) are intermediate in pressure between those published previously for Grampian mineral assemblages in structurally overlying low-pressure migmatites (670–750 °C

A tract of amphibolite facies granitic gneisses and metagabbros in northern Shetland, U.K., is here named the Uyea Gneiss Complex. Zircon U–Pb dating indicates emplacement of the igneous protoliths of the complex c. 2746–2726 Ma, at a later time than most of the Archaean protoliths of the Lewisian Gneiss Complex of mainland Scotland. Calc-alkaline geochemistry of the Uyea Gneiss Complex indicates arc-affinity and a strong genetic kinship among the mafic and felsic components. Zircon Hf compositions suggest an enriched mantle source and limited interaction with older crust during emplacement. Ductile fabrics developed soon after emplacement, with zircon rims at c. 2710 Ma, but there was little further deformation until Caledonian reworking east of the Uyea Shear Zone. There is no evidence for the Palaeoproterozoic reworking that dominates large tracts of the Lewisian Gneiss Complex and of the Nagssugtoqidian Orogen of East Greenland. The more northerly location of the Uyea Gneiss Complex and extensive offshore basement of similar age implies that, prior to the opening of the North Atlantic Ocean, these rocks were contiguous with the Archaean Rae Craton.

U–Pb zircon ages obtained from the late- to post-tectonic ‘Newer Granite’ suite in Shetland, northernmost Scottish Caledonides, indicate a significantly more protracted intrusion history than was inferred previously from K–Ar data. Emplacement of the Brae Complex ( c. 465 Ma), Graven Complex ( c. 440 Ma) and the Muckle Roe Granophyre ( c. 438 Ma) followed regional deformation and metamorphism of metasedimentary successions during the Grampian orogenic event, and is attributed to NW-directed subduction beneath Laurentia. The almost complete absence of plutons of this age along-strike in mainland Scotland suggests a change in subduction angle and/or the distance between the subduction zone and the Laurentian margin. Intrusion of the Ronas Hill Granite ( c. 427 Ma) was approximately coeval with displacement on the Moine Thrust in mainland Scotland, and therefore probably occurred during Baltica–Laurentia collision. A gap of c. 35 myr followed before emplacement of the Mangaster Voe Intrusion and Eastern Granophyre ( c. 390 Ma), and a further gap of c. 20 myr before emplacement of the Sandsting Complex ( c. 370 Ma). Both periods of magmatism are attributed to pulses of localized lithospheric melting in the vicinity of the Walls Boundary Fault during Devonian sinistral relative displacements between Laurentia and Baltica. Supplementary material: Petrological details, full analytical methods and data tables are available at https://doi.org/10.6084/m9.figshare.c.3655706

The collection efficiency of the DustScan DS100 directional sticky pad dust gauge has been analysed in order to estimate airborne dust concentrations for use in atmospheric dispersion models. A DS100 directional sticky pad dust monitor was tested for 10 months at a quarry boundary with respect to a Wilson and Cook (WAC) sampler, with comparisons primarily made with regard to directional wind speeds over the relevant monitoring periods, as recorded by an on-site meteorological station. The mass of dust collected using the DS100 monitor fluctuated between 3.1% and 21.3% of that caught by the WAC sampler over each period. Variations in collection efficiency were modelled using the count of wind speeds per half hour period and two distinct periods were observed. The main trend showed that higher wind speeds decreased relative DS100 efficiency, with low wind speed ( 5 m/s) periods showing modelled efficiency above 10% and below 5% respectively in comparison to the WAC sampler. However, a central period of 9 weeks during the monitoring study showed a reverse of this pattern, with significant wind speeds over 5 m/s correlating with higher DS100 efficiency. Although dust catch on each sampler varied significantly over the study period, an average DS100 efficiency of approximately 7% in comparison to the WAC is suggested for use in estimating airborne dust concentrations for use in atmospheric dispersion models.

Rutile occurs as an accessory mineral in many high-temperature metamorphic assemblages and has the potential to identify and investigate UHT metamorphic terranes. Whilst the use of Zr-in-rutile geothermometry to identify ultrahigh-temperature terranes is appealing, its application to granulites can be difficult owing to diffusional resetting of Zr concentrations during cooling and decompression. In order to provide constraints on P-T conditions and trace element systematics during ultrahigh-temperature metamorphism, metamorphic rutile in granulites from the Archean Napier Complex and the Palaeozoic Rauer Group, Antarctica have been investigated for trace element composition and mineral inclusions/intergrowths. Textural observations and Zr-in-rutile temperatures show that unlike the large proportion of rutiles grains in the matrix, rutile grains that are shielded by phases with low Zr-diffusivities (e.g. orthopyroxene) and/or are in chemical isolation from zircon, have the potential to retain Zr concentrations that correspond to ultrahigh-temperatures. Principal Component Analysis reveals that V, Cr, Nb, Mo, Ta and W are significantly enriched in rutile from Archean and Proterozoic ultrahigh-temperature terranes. High concentrations of elements such as Cr and V indicate a spinel-rich source, demonstrating the effect of protolith bulk chemical composition on rutile trace element signatures. Rutile is shown to contain inclusions and intergrowths of aluminium silicate, quartz, corundum and feldspar, including the first reported occurrence of prograde kyanite, which provides direct evidence that the Napier Complex experienced a typical clockwise P-T evolution.

Plutonic rocks from the Mineiro Belt, Brazil record a delayed onset of the transition from TTG to sanukitoid-type magmatism (high Ba-Sr), starting during the Siderian magmatic lull when little juvenile magma was added to the continental crust. Rocks mostly belong to the calc-alkaline series, meta- to peraluminous and originally “I-type”, meaning that oxidized magmas were formed by partial melting of subducted material. The temporal distribution and apparent secular changes of the magmas are consistent with the onset of subduction-driven plate tectonics due to an increase of the subduction angle and opening of the mantle wedge. New isotopic analyses (Sm-Nd whole rock and Lu-Hf in zircon) corroborate the restricted juvenile nature of the Mineiro Belt and confirm the genetic link between the Lagoa Dourada Suite, a rare ca. 2350 Ma high-Al tonalite-trondhjemite magmatic event, and the sanukitoid-type ca. 2130 Ma Alto Maranhão Suite. U-Pb dating of zircon and titanite constrain the crystallisation history of plutonic bodies; coupled with major and trace element analyses of the host rocks, they distinguish evolutionary trends in the Mineiro Belt. Several plutons in the region have ages close to 2130 Ma but are distinguished by the lower concentration of compatible elements in the juvenile high Ba-Sr suite. Keywords: São Francisco Craton, Magmatic lull, TTG-Sanukitoid transition, Zircon U-Pb-Hf, Titanite U-Pb, Whole rock Nd isotopes

International audience; Apatite has recently gained considerable attention as a mineral with many uses within the Earth and planetary sciences. Apatite chemistry has recently given new insight into a wide range of geological processes and tools, for example, magmatism, metasomatism, planetary geochemistry, and geochronology. We expand the utility of apatite here by presenting a novel way to fingerprint magma chemistry and petrogenesis using apatite inclusions within robust titanite and zircon. We present trace element data from apatite mineral inclusions shielded within magmatic zircon and titanite. Importantly, apa-tite inclusion and host titanite chemistries detailed in this study allow estimation of the whole-rock Sr and SiO 2. We show how these data can be used to assess the degree of fractionation of the host magma and to calculate key trace element abundances and ratios. We demonstrate that the inclusions can be linked to discrete periods in the crystalliza-tion history of the host phases, thus providing insight into petrogene-sis. The results highlight that apatite compositions might discriminate modern granitoids (younger than 2.5 Ga) from Archean-Proterozoic transitional granitoid compositions (sanukitoid signatures). Development of such a petrological tool has important potential for interpretation of provenance and a better understanding of the secular evolution of the continental crust, including that of early Earth.

The Neoproterozoic (c. 870 Ma) West Highland Granitic Gneiss, exposed in the Northern Highlands Terrane of Scotland, has elemental characteristics that are strikingly similar to those of the host Moine metasediments, which are thus consistent with an origin involving major Moine melting. Most of the constituent bodies have compositions significantly removed from minimum melts of pelites, and trace element constraints suggest variable but significant restite entrainment leading to less silicic bulk compositions with enhanced REE, Zr and Y. However, initial Nd and Hf isotope ratios are not coincident with contemporary Moine and imply a significant juvenile contribution. Close association with a regional suite of metabasites prompts consideration of mafic magma input, for which binary mixing models offer qualitative support. Quantitative difficulties with typical Moine metasediments are eased with radiogenic pelites or by partial melting of the mafic component. A possible alternative is currently unexposed Grenvillian felsic crust. Subsequent interaction of the granitic gneisses with meteoric water has significantly perturbed the oxygen and Sr isotope systems, the timing of which is equivocal but probably occurred during Caledonian events. The elemental characteristics of the West Highland Granitic Gneiss show many similarities with Scandinavian (rift-related?) granites of the same age, but since their geochemistry is largely inherited from the protolith it would be unwise to pursue palaeotectonic attribution on this basis. However, the probable incorporation of significant mantle-derived mafic magma of MORB-like affinity is consistent with an extensional setting.

Meta-igneous lithologies of the Cullivoe inlier in NE Yell, Shetland, have tonalite–trondhjemite–granodiorite (TTG) chemistry and yield U–Pb zircon crystallization ages of c. 2856 – 2699 Ma. Formation was coeval with protoliths of the Lewisian Gneiss Complex and the time of major Neoarchaean crustal growth in the North Atlantic Craton. The adjacent metasedimentary Yell Sound Group accumulated between c. 1019 and c. 941 Ma. The Cullivoe inlier and the Yell Sound Group were metamorphosed at c. 944 – 931 Ma, the former preserving granulite-facies mineral assemblages inferred to be of this age. Similar-aged metamorphic events recorded in other Laurentian metasedimentary successions in the North Atlantic region are attributed to development of the Valhalla orogen along the Rodinia margin. Ordovician (482 ± 30 Ma) and Silurian (428 ± 16 Ma) thermal rejuvenation resulted from successive phases of the Caledonian orogeny during closure of the Iapetus Ocean. The mechanism by which the Cullivoe inlier was emplaced into its current structural setting is uncertain. Either its western or eastern boundary is a major tectonic break, probably an early ductile thrust. However, this is now cryptic as a result of the Caledonian ductile reworking. Supplementary material: SIMS and LA-ICP-MS analytical data, statistical analyses and major trace element analytical data are available at https://doi.org/10.6084/m9.figshare.c.3575723.

International audience; Apatite is an excellent tracer of petrogenetic processes as it can incorporate a large range of elements that are sensitive to melt evolution (LREE-MREE, Sr, Pb, Mn, halogens, Nd isotopes). Recent advances in the understanding of trace element concentrations and isotope ratios in apatite provide a novel tool to investigate magmatic petrogenesis and sediment provenance. Recent experimental work has better characterized trace element partition coefficients for apatite, which are sensitive to changes in magma composition (e.g., SiO 2 and the aluminum saturation index value). The chemistry of apatites from granitoids has been suggested to reflect the composition of the host magma and yield information about petrogenetic processes that are invisible at the whole-rock scale (mixing, in situ crystal fractionation, metasomatism). Nd isotopes in apatite can now be analyzed by LA-MC-ICP-MS to constrain mantle and crustal contributions to the source(s) of the studied magma. These recent advances highlight exciting new horizons to understand igneous processes using accessory minerals. In this contribution, we use a compilation of recent data to show that apatite in the matrix and as inclusions within zircon and titanite is useful for providing insights into the nature and petrogenesis of the parental magma. Trace element modeling from in situ analyses of apatite and titanite can reliably estimate the original magma composition, using appropriate partition coefficients and careful imaging. This provides a new way to look at magmatic petrogenesis that have been overprinted by metamorphic processes. It also provides the rationale for new investigations of sedimentary provenance using detrital accessory minerals, and could provide a powerful new window into early Earth processes if applied to Archean or Hadean samples.

This paper describes a study into the development of more robust dust emission factors by means of dust and meteorological monitoring. Emission factors for nuisance dusts in the literature are scarce, with estimates of dust output given for many processes in mass per unit area per year. Temporal variations and the extent and conditions in which maximum concentrations occur can therefore be impossible to predict with any accuracy. This investigation aims to improve predic-tions by “back calculating” emission levels based on dust monitoring around known dust sources. Nuisance dust and meteorological monitoring has been undertaken at a sand and gravel quarry in the UK for a consecutive period of two years. Sticky pad directional dust monitors were used to collect dust at eight locations at and around the site with meteorological data collected at an elec-tronic weather station within the site. Air quality modelling software (ADMS) was used to test emission factors from the European Environment Agency (EEA) and the US Environmental Protec-tion Agency (EPA) for emissions from mineral workings. Predictions were compared with the dust monitoring data to assess accuracy, with results showing limited poor correspondence (r2 < 0.3). Trends showed that emission predictions were poorest in winter; this is likely because most emis-sion calculations are not weather dependent and seasonal fluctuations will occur. Dust emission rate calculations were altered with respect to the dust monitoring data for one monitoring location on the mineral site boundary and the model was run again. Results were then tested at two different locations up to 200 m from the site boundary, with very positive correlations (r2 0.89) and similar maximum concentrations (

Sanukitoids represent a volumetrically minor but important series of Neoarchean granitoids enriched in large-ion lithophile elements (e.g., Ba, Sr, and light rare earth elements), and with relatively high compatible elements (e.g., Mg, Ni, and Cr). Petrogenetic models have favored an origin in the suprasubduction mantle wedge, so their sudden appearance ca. 2.95–2.68 Ga has made them central to the ongoing debate about the beginnings of modern plate tectonics. Caledonian high Ba-Sr granites from the Northern Highlands of Scotland are petrological and compositional equivalents. The Caledonian examples have not undergone subsequent reworking, and their petrogenetic setting can be used to inform genetic models for sanukitoids. Prolonged subduction preceded emplacement of the high Ba-Sr granites in a short interval (∼10 Ma) at the end of the Caledonian orogeny. Sediment subduction was responsible for elemental and isotopic enrichments and slab breakoff triggered melting in the subcontinental lithospheric mantle. This implies that during the Neoarchean the evolving tectonothermal regime moved the locus of melting from the basaltic slab to the sediment-infused mantle wedge, creating the first subcontinental lithospheric mantle. Sanukitoids may then have resulted from widespread, closely subsequent slab-breakoff events, producing evolved magmas by familiar fractionation mechanisms. Careful study of secular variations in high Ba-Sr magmas could constrain the evolution of the subcontinental lithosphere.

Middle-level leaders in schools have a critical role in mentoring teachers as they work with the teaching-as-inquiry process. One-to-one interactions and professional conversations with each teacher largely determine the quality of inquiry, both for an individual teacher and on a school-wide basis. In this article, an experienced senior secondary school leader explores the conditions necessary for school-wide inquiry to flourish, and explains why mentorship needs to be valued and to operate at a range of levels within the school if effective inquiry is to be initiated and sustained.

To investigate whether sediments with subtly different provenances could be recognised within a passive margin setting, samples were taken from Westphalian sedimentary rocks of the Pennine Basin, South Wales Coalfield, Culm Basin of Britain and from Northern Ireland. Although previous work has shown that 3 major source areas were responsible for the infill of the Pennine Basin, this study is restricted to sediments believed to have been derived from the west. Their nominally similar western provenance was confirmed using Sm–Nd isotope techniques and their deposition in a passive margin setting was established using elemental discrimination diagrams. While the overall sediment provenance may have been from the west, the trace element geochemistry indicates that at least two major sediment pathways can be distinguished. Plots of Eu/Eu*–GdN/YbN, along with ternary plots of Cr/V–Ti/Zr–GdN/YbN or Sc/Cr suggest different source areas for the Culm Basin and the South Wales Coalfield. In the Culm Basin the Cr/V ratio generally exceeds 1.25, with a small Eu anomaly and a low GdN/YbN ratio. The Cr/V ratio is less than 1.25 in the South Wales with a larger Eu ratio and a higher GdN/YbN than the Culm Basin. Significant separation of the Culm Basin and the South Wales Coalfield during the early Westphalian by the Bristol Channel–Bray Fault may have been a factor contributing to the provenance differences. Late Carboniferous dextral displacement along this fault brought these basins into close juxtaposition, and it is unlikely that the ‘Bristol Channel Landmass’ formed a common source area for these two basins.

Data are presented from the Batra Formation (also known as the Mudawwara Shale Formation) of a core from well BG-14 in the Batna el Ghoul area, southern Jordan, which enable a new depositional model to be proposed for the middle Rhuddanian (lower Llandovery, Silurian) “hot shale” which may be applicable to other Arabian and North African “hot shales” of similar stratigraphical age. This “hot shale” probably results from rapid early burial of organic carbon associated with a minor regression during which anoxic bottom conditions were maintained for most, but not all, of the time. Evidence for regression comes from (1) increased sediment grain size within the “hot shale” by comparison with underlying shales; (2) palynological changes including a decrease in acritarch species diversity; an increase in the relative abundance of sphaeromorphs, veryhachiids with three processes and acritarchs with short, simple processes; and a decrease in the relative abundance of acanthomorphs; (3) a positive δ13Corg excursion (other Late Ordovician and Silurian positive δ13Corg excursions occur during regressions); and (4) very brief intervals of oxygenation (associated with sediment influx) reflected in the preservation of graptolites as three-dimensional pyrite internal moulds, rather than as flattened periderm. The minor regression reflects a eustatic sea-level fall, evidence for which has recently been presented from several regions, including Arctic Canada, Bohemia and Scotland. The BG-14 “hot shale” is shown to be thicker than estimated in previous studies. Previous TOC measurements from the upper part of the “hot shale” were affected by the weathering of overlying strata in the BG-14 core. ICP-MS measurements show that uranium content is high in these weathered levels, extending the stratigraphical extent of the “hot shale” interval into the middle Rhuddanian. Depositional models such as that presented here rely on a robust biostratigraphical framework; in the Ordovician and Silurian of Arabia and North Africa, this can be provided by graptolites and chitinozoans.

It's clear that managing climate change will require addressing one of its key drivers: coal-fired electricity generation. This likely can’t be done by just avoiding coal use altogether. We need cost-effective CCS and enabling technologies, we need them at commercial scale, and we need them soon.

A variety of high Ba–Sr granites and syenites is intruded into the Caledonian terrane of the Northern Highlands of Scotland. Volumetrically rather small, the plutons display a considerable range of compositions from ultramafic and mafic to granitic and syenitic. Most intrude Proterozoic Moine metasediments, though some are exposed within the Moine Thrust Zone in the west, beyond which lies the Archaean Lewisian foreland. Although it is generally agreed that they are related in some way to the subduction of Iapetus Ocean crust beneath Laurentia, their petrogenesis is much debated, especially the enigmatic relationship between alkaline syenites and calc-alkaline granites. New isotope (Sr–Nd–O) data suggest that both may be derived from mantle sources that include small fractions of subducted pelagic sediment. Juvenile material is volumetrically dominant, although subsequent fractionation involved contamination with local continental crust. Direct derivation from a mafic underplate is unlikely given the absence of pronounced HREE and Y depletion, the major element dissimilarity with adakitic magmas, and the presence of coeval and geochemically-contiguous mantle-derived rocks. The parent magmas were derived from a Caledonian Parental Magma Array (CPMA) that extended from isotopically depleted to significantly enriched compositions, with high δ18O in the latter. The oxygen isotope values and the high Ba–Sr signature in particular strongly suggest that mantle contamination with subducted pelagic carbonates generated the CPMA, and Nd–Sr isotopes constrain the sediment contribution to less than 10%. Differentiation of the parent magmas proceeded by fractional crystallisation and variable concurrent assimilation of small magma batches, involving different crystallising assemblages and different continental reservoirs. Caledonian syenites evolved by extensive pyroxene-dominated fractionation sometimes involving contamination with Lewisian granulites. On the other hand, the granites fractionated amphibole and plagioclase, during which most were contaminated with local Moine metasediment. The extended time interval over which the syenites were intruded (30 Ma) accords with continuing Iapetus subduction beneath the Laurentian margin, while the late pulse of isotopically-variable appinites and granites at about 425 Ma sits comfortably with Scandian slab breakoff. However, the high Ba–Sr granites studied here represent small-volume assimilation-fractionation products of mantle-derived appinitic magmas, rather than the voluminous melts of lamprophyre-underplated crust also predicted by slab breakoff, which are absent from the Northern Highland Terrane.

New field and laboratory work has been carried out on two vitrified forts, Rhubh Aird Ghamhsgail near Arisaig and The Torr near Acharacle. Fieldwork confirms that both are constructed from rubble largely comprising local psammitic Moine Supergroup rocks and that their walls are relatively well preserved with large portions of vitrified material remain, particularly at The Torr, where remnants of up to four courses of stone facing occur. The preserved wall fills comprise mostly psammitic rubble set in a dark brown, vesicular, glassy to aphanitic matrix that in many places preserves evidence of downward flow. Conventionally, vitrification is explained through combustion of timber interlacing within the walls leading to melting that has been modelled in the granite system. However, considering Iron Age smelting technology, this leads to problems in obtaining high temperatures (≥1000 °C) over tens of metres of wall length. Geochemical analysis of the vitrification indicates that modelling the melting within the granite system is incapable of providing a partial melt matching the composition of vitrification. At The Torr, pelite fragments have been found near the base of the wall where partial melt occurs as black bubbles. In these fragments it appears that micas (largely biotite) have formed the melt via the reaction biotite + quartz = sanidine + orthopyroxene + liquid which takes place at temperatures c. 850 °C. Quench crystals in the melt include orthopyroxene, plagioclase, spinels, ilmenite, magnetite, anatase and apatite confirming that it was not a granite melt. These melted fragments are found next to material with biotite that, superficially, appears unmelted, suggesting that some of the heating took place perhaps away from the edifice and unmelted residue was utilised as part of the rubble fill, suggesting that in situ partial melting of the rubble is unlikely. However, in other parts of the edifice heat affected, yet unmelted, fragments are dominant. The new evidence indicates that vitrification occurred at lower temperatures than previously modelled and thus the melts could have been achieved more easily than previously thought.

90.Maternal effects and spatial processes are rightly recognised as being of greatimportance in the life histories of a number of different organisms. Previously, littleeffort has been made for investigating the potential for changes to arise frominteractions between these two crucial processes. Here I tested the outcome ofintroducing a maternal effect on a population of dispersing organisms in differentways, under both spatially homogeneous and heterogeneous conditions, through novelmodification of a well-known population model. First, I proposed that parentscontribute a proportion of offspring based on their own developmental experience. Thisis applied to dispersing organisms as well as those that remain in their natal patch tobreed. I go on to ask how the density of dispersing offspring might be influenced by amaternal effect. What happens if parents that developed under relatively good (or bad)conditions compared to current conditions invest in dispersing offspring? This relaxesthe assumption that populations have perfect knowledge of the local carrying capacity.The results highlight an interesting range of outcomes. By introducing a maternal effectinto the potential future reproductive output otherwise highly unstable populationdynamics were simplified (but not stabilised). If maternal effects affect dispersaldecisions, it is possible for regular cycles with a period consistent with many examplesfrom ecological time-series’ to arise. These results are in agreement with previousstudies, however, by investigating the effects in different aspects of life history, it ispossible to predict the direction of the impact on population dynamics. This work alsohighlights the potential for regular cycles in population dynamics to arise due tomaternal effects, in agreement with recent field studies.M. S. Fowler, Dept of Biological & Environmental Science, Univ. of Helsinki, P.O. Box65 (Viikinkaari 1), FIN-00014 Helsinki, Finland (mike.fowler@helsink.fi).

Geophagia, the intentional and repeated ingestion of soil material, is a complex eating behaviour with incomprehensible aetiology. It is generally assumed that geophagia may help supplement mineral nutrients and thus should not be dissuaded, particularly in subsistence communities. This is largely based on the assumption that a large proportion of mineral nutrients in geophagic materials is potentially available for absorption in the body. We tested this hypothesis on five soils collected from geophagia-prevalent communities by using an in vitro soil ingestion simulation test that is broadly similar to the gastrointestinal (GI) tract. The results show that, despite the soils being rich in mineral nutrients, soil ingestion, inadvertent or through geophagia can potentially reduce the absorption of already bioavailable nutrients, particularly micronutrients such as Fe, Cu and Zn. These in vitro findings, while disagreeing with the commonly held view of geophagia as a source of nutrient supplementation, are consistent with micronutrient deficiency problems observed in clinical nutrition studies conducted amongst geophagic populations. The work also showed that, in some cases, the ingested soils may become a source of Ca, Mg and Mn, although it is not clear why other similar soils should not release any of these mineral nutrients.

The Strathy Complex of the Scottish Caledonides is a bimodal association of amphibolites and siliceous grey gneisses that structurally underlies adjacent metasediments of the Moine Supergroup. Both rock units record a common polyphase Caledonian tectonometamorphic history. New elemental and radiogenic isotope data indicate that both end-members of the Strathy suite were derived from a depleted mantle source, that they are cogenetic and that they may have been related by crystal fractionation. δ18O values and their correlations with major and trace elements suggest that the protoliths were hydrothermally altered at temperatures below 200 °C. Tectonomagmatic discrimination based on relatively immobile elements and isotope systems, plus comparison with geochemically similar bimodal supracrustal associations elsewhere, strongly support the conclusion that the igneous protoliths of the Strathy Complex formed in an oceanic destructive margin setting. If TDM model ages of c. 1000 Ma approximate protolith crystallization, the Strathy Complex may have formed as juvenile crust in the peri-Rodinian ocean broadly contemporaneous with the Grenville orogenic cycle.

This paper describes an investigation into fugitive dust patterns and characteristics at a 200 hectare oil and gas terminal in the Middle East. Dust monitoring took place as part of an environmental and socio-economic impact assessment (ESIA) for proposed construction work, with initial monitoring over three months as part of a baseline study. Once the new phase of construction had started, passive dust monitoring was undertaken for 18 months using an extensive array of sticky pad dust collectors, with samples of dust in directional flux and deposited dust obtained. Dust monitors were placed upwind and downwind of the construction site, near building activities, and adjacent to nearby receptors. Collected dust samples were subjected to basic analysis for dust coverage (AAC %) and dust soiling (EAC %) with further samples later chosen for additional elemental, mineralogical and particle size analysis. Dust was removed from the sticky pads so that elemental analysis could be undertaken using ICP-MS and mineralogical analysis could be completed using SEM-EDX. Particle size analysis was accomplished using laser granulometry. Dust composition was compared with reference to background dust and soils. Results showed that collected dusts, both from the baseline study and construction phase and from background samples and receptors, were comprised of similar major minerals (r2 values > 0.78) to the calcareous sandy silts and clays that make up the majority of local soils. Similar results (r2 > 0.79) were also found for proportions of major elements in background dusts, receptor-collected dusts, and soils. One notable exception to the findings of dust homogeneity was the increased presence of calcite (and thus Ca) in samples near to roads: this is thought to originate from road traffic spillages of limestone which is quarried nearby. Particle size distributions for dust samples were also similar across samples at individual monitoring periods, but seemed to vary temporally in response to differing weather conditions. Weather data from an onsite monitoring station were also collected throughout the study and temporal dust levels were investigated in relation to individual weather factors. High dust levels originating from north of the site were recorded throughout the study period, and were observed to correlate with respective high winds from the north. Dust levels were also significantly increased during summer months and after periods of low rainfall. A predictive model for background dust propagation was therefore developed midway through the study, using wind strength and frequency from the north, temperature, and antecedent rainfall. Background dusts were defined as those arriving from north of the site (330° - 30°) and collected at dust monitors unaffected by construction workings. Linear regression was used to incorporate the different weather parameters into individual weather factors which combined to create a prediction of background dust levels. The resulting model, based on the first year of data, was subsequently tested against recorded levels over the next six months with high levels of accuracy observed (r2 > 0.78). The model was also tested against data collected during the baseline study with further positive results (r2 > 0.67).

Geophagia, the deliberate ingestion of soil, is a complex eating behaviour with obscure aetiology and numerous health/medical problems. It is conventionally assumed that geophagia may help supplement mineral nutrients in individuals with limited intake of trace elements such as Fe and Zn. This view, however, has largely been based on the bulk nutrient composition of geophagic materials and the assumption that these nutrients are potentially available for absorption in the body. We have tested this assumption by equilibrating five geophagic materials collected from Uganda, Tanzania, Turkey and India with mineral nutrient concentrations and conditions similar to the gastrointestinal tract. The results showed that all five geophagic materials, regardless of their composition, sorbed large amounts of Fe and Zn across a range of dietary intake scenarios, even under acidic conditions (pH 2) similar to the stomach. However, significant amounts of Ca desorption were observed from calcareous soil samples. The findings show that while calcareous geophagic materials may supplement Ca, geophagia can potentially cause Fe- and Zn-deficiency. This is consistent with mineral nutrient deficiency problems observed in clinical nutrition studies conducted amongst geophagic populations.

International audience; The Rogart and Strontian high Ba^Sr plutons (Northern Highlands, Scotland) comprise a range of lithologies from felsic to ultramafic rocks. The latter are mantle-derived and their differentiation to produce the felsic components of the plutons is the result of fractional crystallization and variable assimilation of the surrounding Moine metasediments. New results presented here demonstrate that accessory mineral chemistry can provide further insight into their petrogenesis and highlight the petrological potential of apatite and titanite. The main accessory minerals titanite, apatite and zircon contain most of the rare earth elements (REE) in the high Ba^Sr plutons. Results for apatite and titanite show that careful imaging and in situ trace element analysis provide constraints on the petrogenetic history of the host-rock. In both plutons, apatite and titanite record in situ crystallization and fractionation. In Strontian, both apatite and titanite from the granitoids record a mixing event with mafic magma in their rim compositions. Apatite and titanite chemistries are sensitive to the nature of their host-rocks (felsic versus ultramafic) and some elements (e.g. Sr,V) closely reflect whole-rock chemistry and the degree of fractionation. In some cases, whole-rock trace element concentrations can be calculated based on accessory mineral chemistry. Thus, trace elements in accessory minerals can give direct access to the nature and crystallization history of plutonic rocks. This petrological tool may be helpful in provenance studies using accessory minerals, and because high BaŜ r plutons have recently been equated with Archaean sanukitoids, this might also be important in constraining the temporal distribution of this important magma type.

The Rogart pluton is a typical example of high Ba–Sr granitic magmatism, emplaced in northern Scotland towards the end of the Caledonian Orogeny. It consists of three granitoid facies (tonalite, granodiorite, granite) that are locally associated with large enclaves of coeval mafic appinite. The overall range of compositions is therefore extreme, with MgO from 11.6 to 2 from 47.50 to >73.0 wt%, with relatively high Na 2 O+K 2 O especially for the mafic rocks (up to 8.4 wt%), associated with K 2 O/Na 2 O≈1.5. Trace element abundances vary extensively and coherently, and the typical high Ba–Sr elemental signature of the pluton is also carried by the appinites. This is consistent with a genetic relationship throughout the suite. Sr, Nd and O isotope ratios are sufficiently similar to support this contention, but vary systematically with magma evolution. The appinites were derived from an enriched mantle source ( 143 Nd/ 144 Nd 400 ≈0.51194, 87 Sr/ 86 Sr 400 ≈0.7061) with high δ 18 O (≈+8‰), probably related to active contemporaneous subduction. Quantitative elemental and isotopic modelling suggests that the granitoid magmas evolved from the appinites by crystal fractionation accompanied by minor crustal contamination. Early fractionation from appinite to tonalite was driven by crystallization of pyroxene plus biotite with minor plagioclase, replaced by a feldspar-dominated assemblage to produce granodiorite and granite. The total amount of crust assimilated was less than 25%, highlighting the juvenile nature of the high Ba–Sr granite class.

Fugitive dust from industrial activities is a long-standing and intractable problem. Quarrying and mining, construction and demolition, landfill, waste transfer and reprocessing, bulk materials handling (especially at ports, docks and harbours), and arable farming are obvious examples where dust is inevitably produced. The impacts of dust emissions from such activities are broadly recognised but, especially within crowded urban and suburban areas where industry and residential areas are often juxtaposed, there may be many potential dust sources within and beyond any given locality. Consideration of potential fugitive dust impacts from planned industrial sites is a frequent part of environmental and social impact assessment, and subsequent monitoring of dust emissions a necessary test enforced by legislation and/or best practice guidance. Rarely, but in such cases significantly, disputes may arise about the causes and consequences of dust impacts. These can become good examples for environmental forensics, requiring the constraint of source - pathway - receptor with sufficient robust evidence for responsibilities to be established and decisions to be made. Recent developments in passive (unpowered) dust monitoring utilising ‘sticky pad’ samplers (Datson et al., 2011; 2012) have facilitated the monitoring of dust in flux on the pathway between source and receptor, and in deposition at the receptor. When combined with established procedures for elemental analysis (Fowler et al., 2010), source attribution studies become possible. This contribution describes two examples of such work which have been undertaken on behalf of the UK Environment Agency (EA), one related to hazardous waste disposal at a rural landfill site, the other to varied industrial activity in an urban setting. Both studies follow the same overall rationale and use DustScan® monitoring equipment and methods. Briefly, after careful consideration of site circumstances and potential dust sources, directional and/or deposited dust gauges are located between the site and potential receptor(s), and at ‘proxy’ receptor locations. Where possible, an upwind location is included, to help establish the local background dust abundance and character. Guided by the directional dust monitoring data (dust abundance by direction as AAC (absolute area coverage) and/or EAC (effective area coverage)), sub-samples are excised from “arcs of interest” on the sticky pads – each representing the direction that connects source and receptor, to a 15˚ resolution. Sub-samples are also taken from sticky pads used to capture dust in deposition, according to an appropriate and similar logic. These are then subjected to a range of laboratory analyses depending on purpose (and finance), ranging from light and scanning electron microscopy, gravimetry and granulometry, to elemental analysis by ICPAES or ICP-MS. Elemental data form the basis of source attribution, either by judgemental establishment of dust differences based on knowledge of potential source(s), or - if the data set is appropriate - by multivariate statistics and/or chemical mass balance procedures. The first case study (hazardous waste landfill) was commissioned as part of the planning application process for renewal of the site licence. It demonstrates that with sufficient prior knowledge and comparatively simple site circumstances, it is possible to make confident apportionment conclusions based on relatively few samples. The second study reflects work in progress at a more complex site involving several industrial processes, including waste transfer, metals recycling, roadstone coating and waste incineration. It shows that, again with a modest number of samples, sensible constraints can be placed on the potential origin of fugitive dusts and their dispersal into the local environment.

Ach'Uaine Hybrid appinites represent a rare example of lamprophyric magmas that were demonstrably exactly contemporaneous with felsic differentiates, preserved within a suite of minor, hypabyssal intrusions emplaced at the end of the Caledonian orogeny in northern Scotland. Numerous small stocks, bosses and dykes show outcrop-scale relationships characteristic of mingling between lamprophyric and syenitic magmas, and are commonly cut by sharp-sided granite veins. The mafic rocks are characterised by Ni and Cr abundances and MgO sufficiently high to signal derivation from a mantle source within which radiogenic 87Sr/86Sr and nonradiogenic 143Nd/144Nd ratios require significant time-integrated incompatible element enrichment. This is manifest in high Ba, Sr and light REE abundances and incompatible element ratios in the derived magmas directly comparable with those of high Ba-Sr granitoids and related rocks. Quantitative major element, trace element, radiogenic and stable isotope modelling is consistent with early fractionation of clinopyroxene and biotite, accompanied by minor crustal assimilation, having driven the evolving lamprophyric magma to cogenetic syenite. Subsequent derivation of granite required a major change to feldspar-dominated crystal fractionation with continued, still minor contamination. The elemental and isotopic characteristics of the granitic terminus are so similar to high Ba-Sr granitoids both locally and worldwide, that these too may have had large mantle components and represent significant juvenile additions to the crust.