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Cadomian calc-alkaline I-type and within-plate A-type igneous rocks are widespread in the crust of Iran where they are ascribed to a convergent margin associated with the southward subduction of Prototethyan oceanic lithosphere beneath N Gondwana. These rocks are found as unmetamorphosed magmatic rocks and their metamorphic equivalents (mafic to felsic gneisses) could have been generated in both Cadomian arcs and associated rear-arcs. Nearly all these exposures also contain metamorphosed metasediments, whereas Cadomian igneous rocks of central Iran are associated with thick sequences of unmetamorphosed terrigenous rocks. In the Zagros Fold-Thrust belt of S Iran, salt diapirs contain abundant xenoliths of Cadomian igneous and sedimentary rocks in association with evaporites, dolomites, carbonates, and banded iron-salt deposits. This paper presents new zircon U-Pb and geochemical-isotopic data from igneous clasts in the Chah-Banu salt diapir in SE Zagros. Petrographic and geochemical data indicate two different types of rock clasts; calc-alkaline, I-type dacites-rhyolites, and arc-related to E-MORB-OIB-like gabbros, basalts, and dolerites. New zircon U-Pb ages show that dacites formed at 538.2 ± 2.2 Ma, whereas gabbros show ages of 539.0 ± 1.8 Ma. Zircons from dacites have negative εHf(t) values of – 1.1 to – 8.3. In contrast, zircons from gabbros have higher εHf(t) values of +4.5 to +8.5, indicating crystallization from mantle-derived juvenile magmas. Bulk rock Nd-Sr isotopic data (e.g. ɛNd(t) = +0.3 to +4.0 and 87Sr/86Sr(i) = 0.7059 to 0.70848) for gabbros, dolerites, and basalts confirm that these rocks originated from a mantle source similar to enriched parts of the subcontinental lithospheric mantle, whereas dacites and rhyolites (with εNd(t) = −3.4 to −4.1 and 87Sr/86Sr(i) = 0.70806 to 0.70907) show strong interaction with, and/or re-melting of older continental crust. We suggest that the bimodal calc-alkaline and E-MORB-OIB-like magmatic rocks in salt diapirs as well as associated evaporites and sedimentary rocks formed in a retro-arc rifted basin behind the Cadomian magmatic arc. published

Continental-arc igneous rock compositions change in response to the transition from subduction to collision and these changes can reveal how the crust, lithosphere and magma sources evolved. Neotethys-related Late Cretaceous to Pleistocene subduction- and collision-related magmatic rocks from the ~350 km long southeast Urumieh-Dokhtar Magmatic Belt (UDMB) of Iran provide an excellent natural laboratory to better understand these changes. These igneous rocks are well-exposed and moderately eroded to reveal a nearly complete record since subduction initiation at ~95 Ma. We analyzed new samples for major and trace elements (83 samples), Srsingle bondNd isotopic compositions (47 samples), and Usingle bondPb zircon ages (26 samples) and compiled geochemical and geochronological data on the southeast segment of the UDMB. The geochronological data reveal two magmatic pulses at ~80–70 Ma and ~50–0 Ma. Important changes in magmatic compositions reflect initial collision with Arabia at ~32 Ma, changing from normal calc-alkaline to increasingly adakitic immediately after collision began. Five stages can be identified: 1) normal continental-arc magmatism during the Late Cretaceous; 2) arc quiescence in Paleocene and Early Eocene time; 3) Middle-Late Eocene extensional arc magmatism related to slab rollback; 4) early collision and crustal thickening during the Early Oligocene; and 5) slab breakoff, asthenospheric upwelling, and associated adakitic magmatism from Middle Miocene onward. Temporal changes in UDMB magmas reflect the response of the overriding plate to changes in the geometry of the subducting Neotethyan lithosphere and to collision between Arabia and Iran. Crustal thickening and arc narrowing during Miocene to Pleistocene post-collisional magmatism caused adakitic magmatism and associated Cu mineralization. Zircon O-Hf and apatite O isotopes as well as bulk-rock Nd isotopes of Cu-bearing adakitic rocks are similar to other barren rocks, but nearly all fertile rocks have higher Hf/Y, Eu/Eu⁎(n) in zircon and higher Sr/Y, V/Y, Eu/Eu⁎(n) in apatite than barren rocks. published

Freshly erupted volcanic ash contains a range of soluble elements, some of which can generate harmful effects in living cells and are considered potentially toxic elements (PTEs). This work investigates the leaching dynamics of ash-associated PTEs in order to optimize a method for volcanic ash respiratory hazard assessment. Using three pristine (unaffected by precipitation) ash samples, we quantify the release of PTEs (Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, Zn) and major cations typical of ash leachates (Mg, Na, Ca, K) in multiple simulated lung fluid (SLF) preparations and under varying experimental parameters (contact time and solid to liquid ratio). Data are compared to a standard water leach (WL) to ascertain whether the WL can be used as a simple proxy for SLF leaching. The main findings are: PTE concentrations reach steady-state dissolution by 24 h, and a relatively short contact time (10 min) approximates maximum dissolution; PTE dissolution is comparatively stable at low solid to liquid ratios (1:100 to 1:1000); inclusion of commonly used macromolecules has element-specific effects, and addition of a lung surfactant has little impact on extraction efficiency. These observations indicate that a WL can be used to approximate lung bioaccessible PTEs in an eruption response situation. This is a useful step towards standardizing in vitro methods to determine the soluble-element hazard from inhaled ash.

Chromium(VI) contamination of drinking water arises from industrial activity wherever there is a lack of environmental legislation enforcement regarding the removal of such pollutants. Although it is possible to remove such harmful metal ions from drinking water through large-scale facilities, there currently exists no safe and simple way to filter chromium(VI) oxoanions at the point of use (which is potentially safer and necessary in remote locations or humanitarian scenarios). High-surface-area cloth substrates have been functionalized with calixarene molecules for the selective capture of aqueous chromium(VI) oxoanions in the presence of structurally similar anions. This is accomplished by pulsed plasmachemical deposition of a linker layer and subsequent functionalization with dimethylaminomethyl-calixarene (5,11,17,23-tetrakis[(dimethylamino)methyl]-25,26,27,28-tetrahydroxycalix[4]arene). Chromium(VI) oxoanions are captured by simply passing polluted water through the functionalized cloth, while other ions not harmful/beneficial to human health remain in the water. These cloth filters are simple to use, highly selective, and easily recyclable-thus making them attractive for point-of-use application in geographic regions lacking appropriate wastewater treatment plants or flawed environmental monitoring systems. Chromium(VI) pollutants have been successfully removed from real-world contaminated industrial wastewater streams using the dimethylaminomethyl-calixarene functionalized cloths.

New field, geochemical, and geochronological data from the Segama Valley Felsic Intrusions (SVFI) of Sabah, north Borneo, shows them to be arc-derived tonalites; not windows or partial melts of a crystalline basement beneath Sabah. U-Pb zircon ages date emplacement in the Triassic and Jurassic: 241.1 ± 2.0 Ma, 250.7 ± 1.9 Ma, 178.7 ± 2.4 Ma, and 178.6 ± 1.3 Ma; contemporaneous with peaks in magmatism and detrital zircons in Sarawak and west Kalimantan (west Borneo). Isotopic data for Sr, Nd, and Pb from whole rocks, and for Hf and O from zircon all show mantle and/or MORB affinities indicating a mantle-derived origin. Enrichment of fluid mobile trace elements and trace element ratios indicate that the most likely setting for this is in a continuation of the Sundaland continental arc. There is no evidence in the field, geochemical, or zircon U-Pb data for continental basement in the Segama Valley region. The intrusive nature of the Segama Valley tonalites constrains the emplacement age of their supra-subduction zone host rocks to at least the Triassic. This new data expands the Triassic and Jurassic extent of Borneo and the Sundaland arc, and challenges models of Borneo's development predominantly through allochthonous terrane accretion in the Cretaceous. Instead, we propose a model of protracted autochthonous growth through supra-subduction zone crustal extension and associated magmatism.

Highlights • U-Pb zircon ages define Late Neoproterozoic, Paleozoic and Mesozoic magmatic events in NW Iran. • Late Neoproterozoic magmatism is characterized by highly variable εHf(t) values. • Late Paleozoic magmatic pulses show rift-related geochemical signatures with radiogenic εHf(t) values. New geochronological and geochemical data for Late Neoproterozoic to Mesozoic intrusive rocks from NW Iran define major regional magmatic episodes and track the birth and growth of one of the Cimmerian microcontinents: the Persian block. After the final accretion of the Gondwanan terranes, the subduction of the Prototethyan Ocean beneath NW Gondwana during the Late Neoproterozoic was the trigger for high magmatic fluxes and the emplacement of isotopically diverse arc-related intrusions in NW Gondwana. The Late Neoproterozoic rocks of NW Iran belong to this magmatic event which includes intrusions with highly variable εHf(t) values. This magmatism continued until a magmatic lull during the Ordovician, which led to the erosion of the Neoproterozoic arc, and then was followed by a rifting event which controlled the opening of Paleotethys. In addition, it is supposed that a prolonged pulse of rift magmatism in Persia lasted from Devonian-Carboniferous to Early Permian time. These magmatic events are geographically restricted and are mostly recorded from NW Iran, although there is some evidence for these magmatic events in other segments of Iran. The Jurassic rocks of NW Iran are interpreted to be the along-strike equivalents of a Mesozoic magmatic belt (the Sanandaj-Sirjan Zone; SaSZ) toward the NW. Magmatic rocks from the SaSZ show pulsed magmatism, with high-flux events at both ~176–160 Ma and ~130 Ma. The SaSZ magmatic rocks are suggested to be formed along a continental arc but a rift setting is also considered for the formation of the SaSZ rocks based on the plume-related geochemical signatures. The arc signatures are represented by Nb-Ta depletion in the highly contaminated (by upper continental crust) plutonic rocks whereas the plume-related signature of less-contaminated melts is manifested by enrichment in Nb-Ta and high εHf(t) values, with peaks at +0.6 and +11.2. All these magmatic pulses led to pre-Cimmerian continental growth and reworking during the Late Neoproterozoic, rifting and detachment of the Cimmerian blocks from Gondwana in Mid-Late Paleozoic time and further crustal growth and reworking of Cimmeria during the Mesozoic.

An environmental concern with hydraulic fracturing for shale gas is the risk of groundwater and surface water contamination. Assessing this risk partly involves the identification and understanding of groundwater‐surface water interactions because potentially contaminating fluids could move from one water body to the other along hydraulic pathways. In this study we use water quality data from a prospective shale gas basin to determine: if surface water sampling could identify groundwater compartmentalisation by low‐permeability faults; and if surface waters interact with groundwater in underlying bedrock formations, thereby indicating hydraulic pathways. Variance analysis showed that bedrock geology was a significant factor influencing surface water quality, indicating regional‐scale groundwater‐surface water interactions despite the presence of an overlying region‐wide layer of superficial deposits averaging 30–40 m thickness. We propose that surface waters interact with a weathered bedrock layer through the complex distribution of glaciofluvial sands and gravels. Principal component analysis showed that surface water compositions were constrained within groundwater end‐member compositions. Surface water quality data showed no relationship with groundwater compartmentalisation known to be caused by a major basin fault. Therefore, there was no chemical evidence to suggest that deeper groundwater in this particular area of the prospective basin was reaching the surface in response to compartmentalisation. Consequently, in this case compartmentalisation does not appear to increase the risk of fracking‐related contaminants reaching surface waters, although this may differ under different hydrogeological scenarios.

How new subduction zones form is an ongoing scientific question with key implications for our understanding of how this process influences the behavior of the overriding plate. Here we focus on the effects of a Late Cretaceous subduction-initiation (SI) event in Iran and show how SI caused enough extension to open a back-arc basin in NE Iran. The Late Cretaceous Torbat-e-Heydarieh ophiolite (THO) is well exposed as part of the Sabzevar-Torbat-e-Heydarieh ophiolite belt. It is dominated by mantle peridotite, with a thin crustal sequence. The THO mantle sequence consists of harzburgite, clinopyroxene-harzburgite, plagioclase lherzolite, impregnated lherzolite, and dunite. Spinel in THO mantle peridotites show variable Cr# (10–63), similar to both abyssal and fore-arc peridotites. The igneous rocks (gabbros and dikes intruding mantle peridotite, pillowed and massive lavas, amphibole gabbros, plagiogranites and associated diorites, and diabase dikes) display rare earth element patterns similar to MORB, arc tholeiite and back-arc basin basalt. Zircons from six samples, including plagiogranites and dikes within mantle peridotite, yield U-Pb ages of ca. 99–92 Ma, indicating that the THO formed during the Late Cretaceous and was magmatically active for ∼7 m.y. THO igneous rocks have variable εNd(t) of +5.7 to +8.2 and εHf(t) ranging from +14.9 to +21.5; zircons have εHf(t) of +8.1 to +18.5. These isotopic compositions indicate that the THO rocks were derived from an isotopically depleted mantle source similar to that of the Indian Ocean, which was slightly affected by the recycling of subducted sediments. We conclude that the THO and other Sabzevar-Torbat-e-Heydarieh ophiolites formed in a back-arc basin well to the north of the Late Cretaceous fore-arc, now represented by the Zagros ophiolites, testifying that a broad region of Iran was affected by upper-plate extension accompanying Late Cretaceous subduction initiation.

The pathophysiology of the majority of neuropsychiatric disorders, including schizophrenia and mood disorders, involves synaptic dysfunction and/or loss, manifesting as lower levels of several presynaptic and postsynaptic marker proteins. Whether chronic exposure to antipsychotic drugs may contribute to this pattern of synaptic loss remains controversial. In contrast, the mood stabiliser lithium has shown to exhibit neurotrophic actions and is thought to enhance synapse formation. Whilst these data are not unequivocal, they suggest that antipsychotic drugs and lithium have contrasting effects on synapse density. We therefore investigated the effect of chronic exposure to lithium and to two different antipsychotics, haloperidol and olanzapine, on presynaptic Synaptic Vesicle glycoprotein 2A (SV2A) and postsynaptic Neuroligin (NLGN) clusters in the rat frontal cortex. Chronic exposure (28 days) to haloperidol (0.5 mg/kg/d) or olanzapine (7.5 mg/kg/d) had no effect on either SV2A or NLGN clusters and no overall effect on synaptic clusters. In contrast, chronic lithium exposure (2 mmol/L eq./d) significantly increased NLGN cluster density as compared to vehicle, but did not affect either SV2A or total synaptic clusters. These data are consistent with and extend our prior work, confirming no effect of either antipsychotics or lithium on SV2A clustering, but suggest contrasting effects of these drugs on the post-synapse. Although caution needs to be exerted when extrapolating results from animals to patients, these data provide clarity with regard to the effect of antipsychotics and lithium on synaptic markers, thus facilitating discrimination of drug from illness effects in human studies of synaptic pathology in psychiatric disorders.

We present the new approach to AFC modelling published as Editor’s Choice in the July 2019 issue of Journal of Petrology [1].Our new, Equilibrated Major Element – Assimilation with Fractional Crystallisation (EME-AFC) approach simultaneously models the major element, trace element, and radiogenic and oxygen isotope compositions during such magmatic differentiation (including a new approach to oxygen modelling); addressing the lack of current AFC modelling approaches for felsic, amphibole- or biotite-bearing systems. We discuss the application of this model to granitic magmatism in SE Asia and Antarctica, with particular focus on the Mt Kinabalu granitic intrusion of Borneo. We discuss the background to the model, and explain how it can be freely accessed via GitHub [2], and applied to other scenarios of magmatic differentiation; not just granitic magmatism.We present new geochemical data for the composite units of the Mount Kinabalu, and use this to explore the discrimination between crustal- and mantle-derived granitic magmas. The isotopic data (oxygen, Hf, Sr, Nd, and Pb) indicate that the magma cannot be the result only from fractional crystallisation of a mantle-derived magma. Alkali metal compositions show that crustal anatexis is also an unsuitable processes for genesis of the intrusion. Using the new EME-AFC modelling approach, we show that the high-K pluton was generated by fractional crystallisation of a primary, mafic magma followed by assimilation of the partially melted sedimentary overburden. We propose that Mt Kinabalu was generated through low degree melting of upwelling fertile metasomatised mantle driven by regional crustal extension in the Late Miocene.[1] Burton-Johnson, A., Macpherson, C.G., Ottley, C.J., Nowell, G.M., Boyce, A.J., 2019. Generation of the Mt Kinabalu granite by crustal contamination of intraplate magma modelled by Equilibrated Major Element Assimilation with Fractional Crystallisation (EME-AFC). J. Petrol. 60, 1461–1487.[2] https://github.com/Alex-Burton-Johnson/EME-AFC-Modelling

Volcanic ash presents a widespread and common hazard during and after eruptions. Complex interactions between solid ash surfaces and volcanic gases lead to the formation of soluble salts that may be mobilized in aqueous environments. A variety of stakeholders may be concerned about the effects of ash on human and animal health, drinking water supplies, crops, soils and surface runoff. As part of the immediate emergency response, rapid dissemination of information regarding potentially hazardous concentrations of soluble species is critical. However, substantial variability in the methods used to characterize leachable elements makes it challenging to compare datasets and eruption impacts. To address these challenges, the International Volcanic Health Hazard Network ( www.ivhhn.org ) organized a two-day workshop to define appropriate methods for hazard assessment. The outcome of this workshop was a ‘consensus protocol’ for analysis of volcanic ash samples for rapid assessment of hazards from leachable elements, which was subsequently ratified by leading volcanological organizations. The purpose of this protocol is to recommend clear, standard and reliable methods applicable to a range of purposes during eruption response, such as assessing impacts on drinking-water supplies and ingestion hazards to livestock, and also applicable to research purposes. Where possible, it is intended that the methods make use of commonly available equipment and require little training. To evaluate method transferability, an interlaboratory comparison exercise was organized among six laboratories worldwide. Each laboratory received a split of pristine ash, and independently analyzed it according to the protocol for a wide range of elements. Collated results indicate good repeatability and reproducibility for most elements, thus indicating that the development of this protocol is a useful step towards providing standardized and reliable methods for ash hazard characterization. In this article, we review recent ash leachate studies, report the outcomes of the comparison exercise and present a revised and updated protocol based on the experiences and recommendations of the exercise participants. The adoption of standardized methods will improve and facilitate the comparability of results among studies and enable the ongoing development of a global database of leachate information relevant for informing volcanic health hazards assessment.

Spatially resolved soft materials, such as vesicles and microgels, have shown promise as selective adsorbents and microscale reaction vessels. However, spatiotemporal control of aggregation can be difficult to achieve. In this study, nickel(ii) chloride and a dipyridyl oligo(urea) ligand were combined in a vapour-diffusion setup to produce a localised spheroidal aggregate at the liquid–vapour interface. This aggregate forms via the self-assembly and fusion of monodisperse colloids and grows until its weight is no longer counterbalanced by surface tension. A simple physical model reveals that this process, termed lilypad aggregation, is possible only for surface energies that favour neither bulk aggregation nor the growth of an interfacial film. These surface energies dictate the final size and shape of the aggregate and may be estimated through visual monitoring of its changing morphology. Lilypad aggregates sequester metal from the surrounding sol and can be collected manually from the surface of the liquid., Lilypad aggregates are localised spheroidal soft materials formed by the non-equilibrium self-assembly of colloids at a liquid–vapour interface.

Objectives A multi‐isotope study was conducted on individuals buried at Skriðuklaustur monastery (AD 1493–1554) to investigate their geographic origins and dietary composition. Comparative material from individuals excavated from Skeljastaðir, an inland farm site was also analyzed. Materials and methods Bone collagen was extracted from 50 humans (Skriðuklaustur and Skeljastaðir) and 25 animals (Skriðuklaustur) and analyzed for δ13C, δ15N, and δ34S. Dental enamel samples from 31 individuals (Skriðuklaustur) were also analyzed for 87Sr/86Sr, δ18O, δ13C, and trace elements (Pb, Sr, Zn, Ba). Results The mean value determined from individuals from Skriðuklaustur (n = 36) was δ13C = −18.7 ± 0.8‰, δ15N = 12.8 ± 1.1‰, and δ34S = 9.0 ± 1.6‰, whereas at Skeljastaðir (n = 14), it was δ13C = −20.5 ± 0.8‰, δ15N = 7.8 ± 0.9‰, and δ34S = 9.4 ± 1.6‰. At Skriðuklaustur, human dental enamel samples (n = 31) provided a 87Sr/86Sr range of 0.7060–0.7088, δ18Ophosphate from 13.9 to 16.1‰ and δ13Ccarbonate from −16.6 to −12.9‰. Inferred drinking water (δ18Odw) values range from −12.3 to −8.9‰. Sr concentrations range from 25.8 to 156.7 ppm, Ba from 0.11 to 0.81 ppm, Zn from 43.8 to 145.8 ppm, and Pb from 0.13 to 9.40 ppm. Discussion A combination of results indicates that the people from Skriðuklaustur were born in Iceland, but some lived inland during childhood while others lived closer to the coast. Since Skriðuklaustur was a hospital, these individuals may have sought medical treatment at the monastery. The δ13C and δ15N values determined from bone collagen indicate that the people residing at Skriðuklaustur consumed a diet high in marine protein, while those residing at Skeljastaðir exhibit values more consistent with terrestrial resources., This research was financed by Fornminjasjóður (the Archaeology Fund), Háskólasjóður Eimskipafélags Íslands (the Eimskip University Fund), and the Stable Isotope Biogeochemistry Laboratory (SIBL).

Background Volcanic plumes are complex environments composed of gases and ash particles, where chemical and physical processes occur at different temperature and compositional regimes. Commonly, soluble sulphate- and chloride-bearing salts are formed on ash as gases interact with ash surfaces. Exposure to respirable volcanic ash following an eruption is potentially a significant health concern. The impact of such gas-ash interactions on ash toxicity is wholly un-investigated. Here, we study, for the first time, whether the interaction of volcanic particles with sulphur dioxide (SO2) gas, and the resulting presence of sulphate salt deposits on particle surfaces, influences toxicity to the respiratory system, using an advanced in vitro approach. Methods To emplace surface sulphate salts on particles, via replication of the physicochemical reactions that occur between pristine ash surfaces and volcanic gas, analogue substrates (powdered synthetic volcanic glass and natural pumice) were exposed to SO2 at 500 °C, in a novel Advanced Gas-Ash Reactor, resulting in salt-laden particles. The solubility of surface salt deposits was then assessed by leaching in water and geochemical modelling. A human multicellular lung model was exposed to aerosolised salt-laden and pristine (salt-free) particles, and incubated for 24 h. Cell cultures were subsequently assessed for biological endpoints, including cytotoxicity (lactate dehydrogenase release), oxidative stress (oxidative stress-related gene expression; heme oxygenase 1 and NAD(P)H dehydrogenase [quinone] 1) and its (pro-)inflammatory response (tumour necrosis factor α, interleukin 8 and interleukin 1β at gene and protein levels). Results In the lung cell model no significant effects were observed between the pristine and SO2-exposed particles, indicating that the surface salt deposits, and the underlying alterations to the substrate, do not cause acute adverse effects in vitro. Based on the leachate data, the majority of the sulphate salts from the ash surfaces are likely to dissolve in the lungs prior to cellular uptake. Conclusions The findings of this study indicate that interaction of volcanic ash with SO2 during ash generation and transport does not significantly affect the respiratory toxicity of volcanic ash in vitro. Therefore, sulphate salts are unlikely a dominant factor controlling variability in in vitro toxicity assessments observed during previous eruption response efforts.

We present new geochronological and geochemical data for Neogene magmatism from West Sarawak. Zircon U-Pb geochronology divides Neogene magmatic rocks of West Sarawak into a Lower Miocene West Sarawak Sintang Suite with ages of c. 19 to 21 Ma, and a Middle Miocene Bau Suite with ages of c. 12 to 14 Ma. Magmatism occurred in multiple short-lived pulses from approximately 24 Ma and was coeval with magmatic activity in NW Kalimantan and East Kalimantan. The majority of, but not all, Bau Suite samples display adakitic chemistry, while the West Sarawak Sintang Suite is predominantly non-adakitic. There was no active subduction zone or subducted slab associated with this adakitic magmatism. Instead, the geochemical diversity is consistent with the Bau and West Sarawak Sintang suites representing mixtures of mafic, mantle-derived magma with felsic magma derived from remelting of hydrous, mafic rock that had been emplaced into the lithosphere of Borneo as arc basalt tens or hundreds of millions of years previously. This origin is most evident in the main Sintang Suite of central Borneo (Kalimantan) which has preserved less contaminated examples of the mafic endmember. This endmember resembles basaltic rocks from several locations across Borneo suggesting that intraplate, mantle-derived magmatism was responsible for remelting older, hydrated basaltic rocks in the crust.

© 2019 American Journal of Science. All rights reserved. The exposure of organic carbon in rocks to oxidative weathering can release carbon dioxide (CO2) to the atmosphere and consume atmospheric oxygen. Alongside volcanism, metamorphism, and the weathering of carbonate minerals by sulfuric acid, this is a major source of atmospheric CO2 over million year timescales. The balance between CO2 release and CO2 drawdown by silicate weathering and organic carbon burial sets the net geochemical carbon budget during weathering and erosion. However, the rates of rock-derived organic carbon (petrogenic organic carbon, OCpetro) oxidation remain poorly constrained. Here, we use rhenium as a proxy to trace and quantify CO2 release by OCpetro oxidation in the Mackenzie River Basin, Canada, where the other carbon fluxes have been well constrained previously. River water and sediment samples were collected between 2009 and 2013 at gauging stations along the Mackenzie River and its main tributaries (Liard, Peel and Arctic Red). To assess rhenium inputs from silicate, sulfide and OCpetro mineral phases we normalize dissolved rhenium concentrations, [Re]diss, to sodium and sulfate ion concentrations. This approach suggests that >85 percent of Re]diss is derived from OC tro in the main river channels. [Re]diss and water discharge measurements are used to quantify dissolved Re yields. River sediments provide a measure of the Re to OC tro ratio of materials undergoing weathering in the basin, and agree well with published rock samples. Dissolved Re yields are combined with river sediment [Re]/[OCpetro] ratios to estimate the CO2 emissions by OCpetro weathering. These are 0.45+019/-0.11 metric tonnes of carbon, tC km2 yr-1 for the Mackenzie River at Tsiigehtchic (3.8+1.5/0.9 × 104 moles km-2 yr-1), and 0.94+0.41/-0.26 tC km-2yr-1, 0.78+0.35/-0.21tC km-2 yr-1 and 1.01+0.42./-0.25tC km-2 yr-1 for the Peel, Arctic Red and Liard catchments, respectively. When considered alongside published silicate and carbonate weathering rates and the sedimentary burial of biospheric organic carbon, these data suggest that the upper part of the Mackenzie River Basin presently acts as an atmospheric CO2 sink of ∼1 tC km-2 yr-1 (∼8 × 104 moles km-2 yr-1) as a result of the carbon transfers by weathering and erosion. During the Last Glacial Maximum, it is possible that the net geochemical carbon balance may have been very different: potential increases in CO2 emissions from oxidative weathering of OCpetro and carbonate minerals, coupled with reduced biospheric carbon burial, may have tipped the balance to a net source of CO2

New geochemical data are presented for the composite units of the Mount Kinabalu granitoid intrusion of Borneo and utilised to explore the discrimination between crustal- and mantle-derived granitic magmas. The geochemical data demonstrate that the units making up this composite intrusion became more potassic through time. This was accompanied by an evolution of isotope ratios from a continental-affinity towards a slightly more mantle-affinity (87Sr/86Sri ∼0·7078; 143Nd/144Ndi ∼0·51245; 206Pb/204Pbi ∼18·756 for the oldest unit compared to 87Sr/86Sri ∼0·7065, 143Nd/144Ndi ∼0·51250 and 206Pb/204Pbi ∼18·721 for the younger units). Oxygen isotope ratios (calculated whole-rock δ18O of +6·5–9·3‰) do not show a clear trend with time. The isotopic data indicate that the magma cannot result only from fractional crystallization of a mantle-derived magma. Alkali metal compositions show that crustal anatexis is also an unsuitable process for genesis of the intrusion. The data indicate that the high-K units were generated by fractional crystallization of a primary, mafic magma, followed by assimilation of the partially melted sedimentary overburden. We present a new, Equilibrated Major Element -Assimilation with Fractional Crystallization (EME-AFC) approach for simultaneously modelling the major element, trace element, and radiogenic and oxygen isotope compositions during such magmatic differentiation; addressing the lack of current AFC modelling approaches for felsic, amphibole- or biotite-bearing systems. We propose that Mt Kinabalu was generated through low degree melting of upwelling fertile metasomatized mantle driven by regional crustal extension in the Late Miocene.

Macroalgae (seaweed) has been shown to be an effective environmental indicator. We investigate the trace element chemistry of macroalgae samples from locations along the Firth of Forth and Forth Estuary in Scotland. The overall trend in elemental abundance (Os ≪ Re

Volcanism is the surface expression of magma intrusion, crystallization, assimilation and hybridization processes operating throughout the crust over a range of time periods. Many magmas, including those erupted at subduction zones, have complex textures that reflect these processes. Here, we use textural and geochemical characteristics of calcic amphiboles to help identify multiple ingredients of subduction zone magmatism at Mt Lamington volcano, Papua New Guinea. Our approach uses existing trace element partitioning schemes to calculate the compositions of amphibole equilibrium melts (AEMs). The AEM compositions show that Mt Lamington andesites and plutonic enclaves are dominated by fractionation of amphibole + plagioclase + biotite, with assimilation of plagioclase and zircon. Magnesiohastingsite crystals in the andesite and diktytaxitic mafic enclaves reflect multiple episodes of recharge by more primitive, geochemically variable melts. The andesite also contains clots with rounded grains and melt on grain boundaries. These features indicate slow crystallization, and the retention of melt films could significantly enhance the potential for remobilization of crystals by infiltrating melts or during magma mixing. Variations in crystallization conditions could thus significantly affect the mush microstructure. We suggest that this could result in a significant bias of the volcanic record towards the preferential incorporation of more slowly cooled plutonic material from the lower crust or from more thermally mature plumbing systems. This article is part of the Theo Murphy meeting issue ‘Magma reservoir architecture and dynamics’.

Positron emission tomography studies using the synaptic vesicle glycoprotein 2A (SV2A) radioligand [11C]-UCB-J provide in vivo evidence for synaptic dysfunction and/or loss in the cingulate and frontal cortex of patients with schizophrenia. In exploring potential confounding effects of antipsychotic medication, we previously demonstrated that chronic (28-day) exposure to clinically relevant doses of haloperidol does not affect [3H]-UCB-J radioligand binding in the cingulate and frontal cortex of male rats. Furthermore, neither chronic haloperidol nor olanzapine exposure had any effect on SV2A protein levels in these brain regions. These data do not exclude the possibility, however, that more subtle changes in SV2A may occur at pre-synaptic terminals, or the post-synaptic density, following chronic antipsychotic drug exposure. Moreover, relatively little is known about the potential effects of psychotropic drugs other than antipsychotics on SV2A. To address these questions directly, we herein used immunostaining and confocal microscopy to explore the effect of chronic (28-day) exposure to clinically relevant doses of haloperidol, olanzapine or the mood stabilizer lithium on presynaptic SV2A, postsynaptic Neuroligin (NLGN) puncta and their overlap as a measure of total synaptic density in the rat prefrontal and anterior cingulate cortex. We found that, under the conditions tested here, exposure to antipsychotics had no effect on SV2A, NLGN, or overall synaptic puncta count. In contrast, chronic lithium exposure significantly increased NLGN puncta density relative to vehicle, with no effect on either SV2A or total synaptic puncta. Future studies are required to understand the functional consequences of these changes.

Aragonitic speleothems are increasingly utilised as palaeoclimate archives due to their amenability to high precision U–Th dating. Proxy records from fast-growing aragonitic stalagmites, precisely dated to annual timescales, can allow investigation of climatic events occurring on annual or even sub-annual timescales with minimal chronological uncertainty. However, the behaviour of many trace elements, such as uranium, in aragonitic speleothems has not thus far been as well constrained as in calcitic speleothems. Here, we use uranium concentration shifts measured across primary calcite-to-aragonite mineralogical transitions in speleothems to calculate the distribution coefficient of uranium in aragonitic speleothems (derived DU = 3.74 ± 1.13). Because our calculated DU is considerably above 1 increased prior aragonite precipitation due to increased karst water residence time should strongly control stalagmite aragonite U/Ca values. Consequently, uranium concentrations in aragonitic speleothems should act as excellent proxies for effective rainfall.\ud \ud We test this using a high-resolution ICP-MS derived trace element dataset from a Belizean stalagmite. YOK-G is an aragonitic stalagmite from Yok Balum cave in Belize with an extremely robust monthly-resolved chronology built using annual δ13C cycles. We interpret seasonal U/Ca variations in YOK-G as reflecting changes in the amount and seasonality of prior aragonite precipitation driven by variable rainfall amounts. The U/Ca record strongly suggests that modern drying has occurred in Belize, and that this drying was primarily caused by a reduction in wet season rainfall. This is consistent with published stable isotope data from YOK-G also very strongly suggesting modern rainfall reductions, previously interpreted as the result of southward ITCZ displacement. Our results strongly suggest that U/Ca values in aragonitic speleothems are excellent proxies for rainfall variability. This new tool, combined with the exceptional chronological control characteristic of aragonitic stalagmites and the high spatial resolution afforded by modern microanalytical techniques, should facilitate the construction of new exquisitely resolved rainfall records, providing rare insights into seasonality changes as well as long-term changes in local recharge conditions.

Introduction: The combination of platinum-based chemotherapy with inhibitors of the DNA damage response (DDR) is therapeutically challenging due to overlapping toxicities, such as myelosuppression. The optimal sequence and schedule of drug delivery to mitigate toxicity and maximise efficacy has not been determined for many combinations. Ceralasertib is an oral inhibitor of ATR, a key constituent of the DDR. Ceralasertib has entered early phase clinical trials in combination with carboplatin (NCT02264678). The aim of the current study was to investigate the mechanism of interaction of ceralasertib with platinum (Pt) chemotherapy, characterising the formation and removal of Pt-induced DNA adducts, in order to provide insight into the repair and recovery of DNA following combination treatment. Methods: The growth inhibitory effects of ceralasertib alone and in combination with cisplatin were tested using sulphorhodamine B (SRB) colorimetric assays in a panel of non-small cell lung (H460 and H23) and breast (MCF7, T47D, HCC1806, MDA-MB-436 and MDA-MB-468) cancer cell lines. Median effect analysis using CalcuSyn software (Biosoft, Cambridge, UK) was used to evaluate synergistic combinations. Time- and schedule-dependent analyses of Pt-DNA adduct formation in cells treated with the combination were carried out using inductively-coupled mass spectrometry (ICP-MS). Cell cycle analysis and DNA replication combing assays were performed to explore alternative mechanisms of synergy between ceralasertib and cisplatin. Results: Ceralasertib was synergistic with cisplatin, inhibiting growth across the cell line panel. However, neither pre-exposure with either agent or co-exposure of cisplatin treated cells to ceralasertib affected the total number, nor longevity, of Pt-DNA adducts compared with cisplatin treatment alone. Continued exposure to ceralasertib for up to 48 hours following wash out of cisplatin (after 4, 8 or 24 hours treatment) did not maintain Pt-induced adducts within the DNA. Peak Pt-DNA adduct formation did not consistently correlate with cell line sensitivity to either drug, combination synergy score, or the effects of ceralasertib or cisplatin on cell cycle progression. Combination treatment did result in a reduction in replication fork speed, but this effect was no greater than that seen with ceralasertib monotherapy. Conclusion: Synergy was observed between cisplatin and ceralasertib in the cell lines tested. However, our in vitro data suggests that this is not associated with an interaction at the level of Pt-DNA adduct formation. Citation Format: Sally E. Hall, Alan Lau, Emma Dean, Elizabeth Martin, Christopher Ottley, Yvette Drew, Gareth Veal. In vitro evaluation of platinum chemotherapy combinations with the ATR inhibitor, ceralasertib (AZD6738) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1385.

Stratabound deposits within late Carboniferous carbonate units in the Middle–Lower Yangtze River metallogenic belt are important copper producers in China. Hitherto, the genesis of these deposits has been debated, due to poor constraints regarding the timing and source of the mineralization. Proposed models include a late Carboniferous seafloor exhalative formation (SEDEX), or an Early Cretaceous magmatic-hydrothermal origin. These models imply different metal sources (basinal vs. magmatic fluid, respectively) and would require different exploration strategies. New pyrite Re-Os and trace-element results from the representative Xinqiao Cu-S-Fe-Au deposit favor a Cretaceous (ca. 138 Ma) magmatic-hydrothermal genesis over a SEDEX origin. The distinct initial 187Os/188Os compositions (Osi) of different pyrite types (colloform Osi = 1.35 and euhedral grains Osi = 0.79), coupled with the pyrite trace-element abundance, indicate that the Os, and by inference other metals (e.g., Cu, Ag, Au), was sourced from a Cretaceous magmatic-hydrothermal system (Osi = 0.74) and Late Permian metalliferous black shales (Osi = 7.56 ± 3.76). In addition, the genesis of Au-bearing stockwork pyrite veins hosted by the Carboniferous sandstone is best explained by the leaching of existing mineralization (e.g., porphyry Au-Mo) by Early Cretaceous magmatic-hydrothermal fluids. This is implied by the lack of common Os, high Re abundances (0.1–3.7 ppm), and highly variable Re-Os model ages (379 and 173 Ma), which are positively correlated with Re and total abundances of Co, Ni, Ag, Au, Tl, and Ba. This study highlights the importance of recycling of multisourced metals (sedimentary and existing mineralization) in the formation of intrusion-related stratabound deposits. Furthermore, it demonstrates the importance of integrating information regarding the source and timing of mineralization within a well-defined geological framework, which can yield information about the ore-forming processes and help to guide mineral exploration.

Podiform chromitites are common within the mantle section of the Late Cretaceous Sabzevar ophiolite in NE Iran. We studied chromitite pods and related ultramafic rocks from three Sabzevar massifs: Baghjar-Kuh Siah, Gaft Chromitite Mine and Forumad peridotite–chromitite. These represent an upper mantle sequence just below the Sabzevar Moho. The Baghjar-Kuh Siah mantle sequence contains plagioclase lherzolites, enriched in bulk REEs, with low Cr# spinels and MORB-like clinopyroxenes. These lherzolites formed due to the impregnation of MORB-like melts. The Gaft and Forumad harzburgites are depleted in trace and rare earth elements and thus are residues after high degree of partial melting (more than exhaustion of Cpx). The Gaft Chromitite Mine includes two types of podiform chromitites, high Cr# and low Cr#. The melt precipitating high Cr# spinel was boninitic whereas the melt forming the low Cr# chromitites was tholeiitic. Most Forumad massif chromitites have high Cr# spinels, although those rich in silicate inclusions are aluminous. Trace and REE element patterns of Forumad harzburgite clinopyroxene are similar to those in supra-subduction zone (SSZ) peridotites while those of Baghjar-Kuh Siah lherzolites are similar to MOR peridotite clinopyroxenes. These mineral data are also consistent with bulk rock trace and rare earth elements composition of their host peridotites. Field observations indicate that early tholeiitic magmas were followed by late boninites, as revealed in chromitite compositions as well as mantle rocks and dikes. We suggest a time-integrated model for the evolution of the Sabzevar mantle sequence during an early stage of subduction initiation associated with formation of an incipient arc. In this scenario, MORB-like melts (forearc basalts) formed first, causing low Cr# chromitites and plagioclase–clinopyroxene impregnations. Subsequent arc-like or boninitic melts with increasing contribution of slab-derived fluids were responsible for the formation of replacive dunites and high Cr# chromitites.

Straight Plant Oils (SPOs) are promising alternatives to diesel fuel in some particular applications, e.g. electrification in remote areas and sustainable modernization of artisan fishing vessels. Moderate commercialization of SPOs is yet to be realized due to lack of critical information on engine durability, lubricant degeneration, and effective methods to offset the adverse effect of directly using SPOs on diesel engines. In this paper, the experimental study evaluates the long term impacts of crude Jatropha oil (JO) on a small diesel engine generator through 300 hour durability tests. The testing results demonstrate the evolution of gaseous emissions, the trace metal element variations in lubricant, and the carbon deposit formation on engine components. The associated fuel spray experiments in the controlled environment further reveal JO atomization patterns and provide important evidence to interpret why JO has greater influence on engine durability than diesel.

Mountain glaciation greatly enhances oxidative weathering rates of organic carbon in rocks and associated carbon dioxide release., Over millions of years, the oxidation of organic carbon contained within sedimentary rocks is one of the main sources of carbon dioxide to the atmosphere, yet the controls on this emission remain poorly constrained. We use rhenium to track the oxidation of rock-bound organic carbon in the mountain watersheds of New Zealand, where high rates of physical erosion expose rocks to chemical weathering. Oxidative weathering fluxes are two to three times higher in watersheds dominated by valley glaciers and exposed to frost shattering processes, compared to those with less glacial cover; a feature that we also observe in mountain watersheds globally. Consequently, we show that mountain glaciation can result in an atmospheric carbon dioxide source during weathering and erosion, as fresh minerals are exposed for weathering in an environment with high oxygen availability. This provides a counter mechanism against global cooling over geological time scales.

The Neyriz ophiolite along the northeast flank of the Zagros fold-thrust belt in southern Iran is an excellent example of a Late Cretaceous supra-subduction zone (SSZ)-related ophiolite on the north side of the Neotethys. The ophiolite comprises a mantle sequence including lherzolite, harzburgite, diabasic dikes, and cumulate to mylonitic gabbro lenses, and a crustal sequence comprising a sheeted dike complex and pillow lavas associated with pelagic limestone and radiolarite. Mantle harzburgites contain less CaO and Al2O3, are depleted in rare earth elements, and contain spinels that are more Cr-rich than lherzolites. Mineral compositions of peridotites are similar to those of both abyssal and SSZ- peridotites. Neyriz gabbroic rocks show boninitic (SSZ-related) affinities, while crustal rocks are similar to early arc tholeiites. Mineral compositions of gabbroic rocks resemble those of SSZ-related cumulates such as high forsterite olivine, anorthite-rich plagioclase, and high- Mg# clinopyroxene. Initial εNd(t) values range from +7.9 to +9.3 for the Neyriz magmatic rocks. Samples with radiogenic Nd overlap with least radiogenic mid-ocean ridge basalts and with Semail and other Late Cretaceous Tethyan ophiolitic rocks. Initial 87Sr/86Sr ranges from 0.7033 to 0.7044, suggesting modification due to seafloor alteration. Most Neyriz magmatic rocks are characterized by less radiogenic 207Pb/204Pb (near the northern hemisphere reference line), suggesting less involvement of sediments in their mantle source. Our results for Neyriz ophiolite and the similarity to other Iranian Zagros ophiolites support a subduction initiation setting for its generation.

Sub-micrometer inclusions in fibrous diamond growth zones carry high-density fluids (HDF) from which the host diamonds have precipitated. The chemistry of these fluids is our best opportunity of characterizing the diamond-forming environment. The major and trace element patterns of diamond-forming fluids vary widely. Such elemental signatures can be easily modified by a variety of mantle processes whereas radiogenic isotopes give a clear fingerprint of the time-integrated evolution of the fluid source region. Thus, the combination of elemental and isotope data is a powerful tool in constraining the origin of fluids from which diamonds precipitate. Here we present combined trace element composition (34 diamonds) and Sr isotopic data (23 diamonds) for fluid-rich diamonds from six worldwide locations. The Nd and Pb isotopic composition of two of the diamonds were also obtained. Several of the samples were analyzed in at least 2 locations to investigate variations in the fluid during diamond growth. The data was acquired using an off-line laser sampling technique followed by solution ICPMS and TIMS analysis. The Sr isotopic compositions of diamond fluids from the different suites range between convecting mantle values for Udachnaya ( 87 Sr/ 86 Sr 363 = 0.70300 ± 16 to 0.70361 ± 4), to highly enriched values, up to 87 Sr/ 86 Sr = 0.72330 ± 3, for a diamond from Congo. No isochronous relationships were observed in any of the suites. The lowest Nd isotopic composition recorded so far in a diamond is from Congo ( e Nd71 = −40.4), which also contains the most radiogenic Sr isotopic composition. In contrast, a less enriched but still rather unradiogenic Nd isotope composition ( e Nd540 = −11) was obtained for a diamond from Snap Lake, which has moderately radiogenic Sr isotopic enrichment ( 87 Sr/ 86 Sr 540 = 0.70821 ± 1). The Pb isotopic system measured in one diamond indicates a complex evolution for the fluid source, with extreme 207 Pb/ 204 Pb ratio (15.810 ± 3) and moderate, kimberlite-like 206 Pb/ 204 Pb and 208 Pb/ 204 Pb ratios. A multi-stage evolution of the diamond-forming fluids source can be constrained from our new isotopic data, indicating an Achaean enrichment event resulting in elevated U/Pb, Rb/Sr ratios and enrichment in LREEs. This source underwent a more recent fractionation, in the last 500 Myr that may have been related to the diamond-forming event. There is a strong correspondence between fluids with relatively unradiogenic Sr isotopes and relatively low (La, Nd, Sm)/(Nb, Zr) and (Ba, Th)/(Nb) ratios. Sr isotopic enrichment is accompanied by an increase in these ratios. The least trace element enriched and most isotopically depleted fluids are from the high-Mg carbonatitic suite. Thus, HDFs could be derived from asthenospheric mantle as low degree melts that interact to varying degrees with an ancient, metasomatized, rutile- and phlogopite bearing, sub continental lithosphere mantle. The internal heterogeneity in the Sr isotopic ratios within a single diamond suite and even within single diamonds may indicate fluid-mixing processes. Such mixing may occur during migration through preferred mantle veins and may be affected by the small-scale geochemical variability within them.

The Paleocene lava succession of the Faroe Islands Basalt Group (FIBG), which is a part of the North Atlantic Igneous Province (NAIP), is intruded by numerous basaltic sills. These can be grouped into three main categories according to their geochemical characteristics: A low-TiO2 sill category (TiO2 = 0.7-0.9), a relatively high-TiO2 sill category (TiO2 = 1.95-2.6) and an intermediate-TiO2 sill that displays major element compositions lying between the other two categories. Mantle normalised plots for the high-TiO2 and low-TiO2 sills display relatively uniform flat LREE trends and slightly steeper HREE slopes for high-TiO2 relative to low-TiO2 sills. The intermediate-TiO2 Morskranes Sill is LREE depleted. Mantle normalised trace elements of low-TiO2 sill samples define positive Eu and Sr anomalies, whereas high-TiO2 sill samples display negative anomalies for these same lements. Different Nb and Ta anomalies (positive versus negative) in many high-TiO2 versus low-TiO2 sill samples suggest various metasomatism of their sources prior to partial melting. The intermediate-TiO2 sill displays noticeably lower 87Sr/86Sr, 206Pb/204Pb and 208Pb/204Pb ratios relative to both the high-TiO2 and the low-TiO2 sill samples. Pb isotope compositions displayed by local contaminated basaltic lavas imply that some of these assimilated distinct crustal material from E Greenland or basement from NW Britain, while others probably assimilated only distinct E Greenland type of crustal material. A third crustal source of E Greenland or Rockall-type basement could be required in order to explain some of the range in lead isotopes displayed by the intermediate-TiO2 Morskranes Sill. Geochemical modelling suggest that Faroese high-TiO2 sills, could have formed by ~4 to 7.5% batch melting of moderately fertile lherzolites, while 16 to 21% batch melting fertile mantle sources could explain geochemical compositions of Faroese low-TiO2 sills. The intermediate-TiO2 sill samples could have formed by a range of 6 to 7% batch melting of a depleted mantle source, probably with a composition comparable to sources that gave rise to local low-TiO2 and intermediate-TiO2 host-rocks. Most Faroese sill samples probably developed outside the garnet stabilitry field and probably formed by batch melting of mantle materials comparable in composition to those reported for the sub-continental lithospheric mantle (SCLM) previously at depths of ≤ 85 km. Relative enrichments in LREE (and LILE in general), and their varying Nb and Ta anomalies point to sources affected by metasomatism.

A 13-month long, daily-scale drip water dataset collected by an automatic water sampling device placed in a small cave in Ireland provides evidence for seasonal shifts in hydrochemistry, including a pulse of colloidally-associated elements in the late summer. Ca, Sr, Mg, Na, Ba, P, Cu, Zn, Rb, Y, Cs, U, Th, and Pb concentrations of the collected water samples were determined, and flow rates were also calculated. Alkali and alkali earth metals decreased in concentration during a summer water deficit, whereas colloidally-associated element concentrations increased during the same interval and spiked dramatically in the late summer/early autumn. The observed increase in colloidally-associated element concentrations may have coincided with increased breakdown of soil organic material by microorganisms in the late summer/early autumn, which led to an increased flux of organic colloids in the drip water, or it may relate to increased rates of dry deposition from cave air. The decrease in alkali and alkali earth metal concentrations in the summer most likely resulted from the addition of dilute water linked to condensation of water vapor above the drip site. Drip water Sr and P concentrations are anticorrelated, and their variation over the study period resembles seasonal trends observed in stalagmite calcite at other sites. Because the Sr minima and P maxima are interpreted as reflecting different phenomena (increased proportion of condensation water relative to karst water, and an increased flux of organic colloids, respectively), the relative timing of these two mechanisms in the past may explain the shifting polarity of their correlation observed in some stalagmite trace element records.

Trace element compositions of raw clay, fired clay and Roman ceramic building material (CBM) from Carpow Roman fortress, Newburgh, Scotland and the city of York, England have been determined through the use of inductively coupled plasma-mass spectrometry (ICPMS). It is confirmed that the firing of clay does not disturb any of the sample’s trace element composition and that trace element protolith identification is an applicable tool for fingerprinting the source of material used in CBM construction. It is also demonstrated through the particular proportions of LREE/HREE; Th/Co; La/Sc; La/Lu; Eu/Sm values on CBM from Carpow that these material were likely manufactured from clay used in the York Roman tile manufacturing industry, therefore suggesting importation. The transport of CBM from York to Carpow provides a useful addition to known examples of the long-distance shipping of CBM. It is postulated that similar analysis to that conducted here could be used to identify important trade networks within the Roman Empire.

The boundary between the Gondwana and Laurussia, or a terrane separated from it, is traced by a suture recording the closure of the Rheic ocean in the Pulur, Beycam and Kurtoglu areas of the eastern Sakarya Zone of Turkey. Pulur lherzolite has a lower Cr# [100Cr/(Cr + Al) = 5−37] of the spinel and slightly enriched flat medium-heavy rare earth element (M-HREE) whole-rock pattern typical for those of the fertile abyssal-type lherzolite. By contrast, the Beycam harzburgite displays the mineralogical and geochemical features of a moderately depleted residue at a supra subduction zone (SSZ). Some of spinels from the Beycam peridotites show TiO2 contents (0.15–0.48 wt.%) identical to a later interaction with a melt of island-arc tholeiite (IAT) composition. Meta-basalt from the Beycam area is the representative of such a melt and displays the whole-rock M-HREE pattern of a complementary product of the Beycam harzburgite. Data presented in this study support the primarily northward directed closure of the Rheic ocean, but suggest that the Variscan basement in the eastern part of the Sakarya Zone consists of mantle peridotites formed in a south-vergent SSZ. This dual polarity of subduction in the Rheic ocean, at least in the second half of its closure, is also favored by the geological structure and lithological diversity of the Variscan rocks. These are: (1) spatial distribution of the peridotites, e.g., SSZ-type harzburgites to the north and abyssal-type lherzolites to the south, (2) lack of high-pressure metamorphic rocks, (3) decrease in the degree of Variscan metamorphism toward the north, and (4) emplacement of Variscan syn-collisional magmatism into the low grade metamorphic rocks to the north. Paleotethys was the other ocean of the region created in the Late Paleozoic. Northward subduction of the Rheic ocean from Early Devonian to Early Carboniferous appears to be the most plausible mechanism responsible for the opening of Paleotethys. In this scenario the Paleotethys is envisaged as a back-arc basin opened to the north in the wake of separated terranes from Laurussia. Onset of trench-Rheic mid-ocean ridge collision in the Early Devonian along the northern margin of Laurussia has been proposed to account for the initiation of SSZ-type subduction to the south. The short duration of this subduction appears insufficient to open a fully developed back-arc basin to the south because the elimination of Rheic mid-ocean ridge to the north accelerated the oceanic closure.

Background: On the basis of preclinical studies of NC-6004, a cisplatin-incorporated micellar formulation, we hypothesised that NC-6004 could show lower toxicity than cisplatin and show greater anti-tumour activity in phase I study Methods: A total of 17 patients were recruited in a range of advanced solid tumour types. NC-6004 was administered intravenously (i.v.) every 3 weeks. The dose escalation started at 10 mg m−2 and was increased up to 120 mg m−2 according to the accelerated titration method and modified Fibonacci method. Results:One dose-limiting toxicity (DLT) occurred in a patient who was given 90 mg m−2 of NC-6004, otherwise any significant cisplatin-related toxicity was not observed or generally mild toxicity was observed. Despite the implementation of post-hydration and pre-medication regimen, renal impairment and hypersensitivity reactions still developed at 120 mg m−2, which led to the conclusion that the maximum tolerated dose was 120 mg m−2, and the recommended dose was 90 mg m−2, although DLT was not defined as per protocol. Stable disease was observed in seven patients. The maximum concentration and area under the concentration–time curve of ultrafilterable platinum at 120 mg m−2 NC-6004 were 34-fold smaller and 8.5-fold larger, respectively, than those for cisplatin. Conclusion:The delayed and sustained release of cisplatin after i.v. administration contributes to the low toxicity of NC-6004 Refereed/Peer-reviewed

We present an integrated microsampling trace element and isotopic study of primary minerals within the Jos kimberlite, Canada, in order to observe how different phases record progressive crustal interaction in the evolving kimberlite. Identification of the least contaminated phases provides the best information on kimberlite source geochemistry. We also carried out an analogue study on an olivine melilitite from Saltpetre Kop, South Africa, examining a similar mineral suite, with the addition of melilite. The two studies show that all phases except phenocryst olivine show some evidence of crustal modification. Perovskite has recently been used as a proxy for source isotope composition. Although perovskite may provide a better constraint on the isotopic composition of the kimberlite than the whole rock, it does not necessarily provide the best constraint on the source region. The lower initial 87Sr/86Sr ratio recorded by early crystallising phases in the kimberlite is similar to those of the low-Cr megacryst suite, strengthening the genetic relationship between kimberlite activity and megacryst formation.

article i nfo In this contribution we present platinum-group element (PGE) abundance and Os isotope data of North Atlantic Craton peridotite xenoliths (n=62) sampled from four major clusters of kimberlite/ultramafi cl amprophyre volcanism in W. Greenland. In addition, we analysed olivine separates from selected peridotites. We find distinct differences in peridotites sampled from the northern (including the reworked Archean Nagssuqtoqidian mobile belt) and southern portions of the W. Greenland fragment of the NAC (WG-NAC). The heavilyserpentinizedharzburgitictoduniticperidotitesfromthenorthernWG-NACaretypicallymarkedbyOsand Ir abundances that are somewhat lower than those of primitive mantle. Pt and Pd abundances are significantly depleted resulting in chondrite-normalized PGE patterns consistent with extensive melt extraction. As a consequence of the meltingprocess,removal of sulphideandpossibly aportionof residual PGE-richalloysislikely. Typically, Os isotopes of these northern samples are unradiogenic (γOs= −14.2 to −6.6, average ca.−9.2), with separated olivines being similar in composition. The unradiogenic Os isotope compositions of the northern peridotites result in TRD erupt model ages clustering between 2.7 and 3.2 and also at ca. 2.0 Gyr. The grouping of the

The Antalya ophiolites (AO) in SW Turkey comprise remnants from the southern branch of the Neotethyan oceanic basins. The mantle peridotites of the AO include spinel lherzolite, harzburgite, and dunite. Harzburgites are dominant over spinel lherzolites in the AO, whereas dunites occur exclusively as ‘envelopes’ surrounding chromitite pods hosted by harzburgite. Petrographic and geochemical data from the peridotites show a progression from fertile to ultra-refractory character, reflected by a progressive decrease in bulk rock contents of Al2O3, CaO, SiO2, TiO2, Sc, V and Y, modal clinopyroxene, Al2O3 content of pyroxenes, and an increase in mafic phase Mg#s and spinel Cr#s (Cr#: 18.0–39.6% in spinel lherzolites, 33.2–77.8% in harzburgites, and 68.7–72.2% in dunites). The chondrite-normalized REE patterns of the AO spinel lherzolites have LREE depleted signature showing steep slopes from HREE to LREE, and are compatible with the residue of a low degree (8–18%) of partial melting of N type MOR mantle. Their mineral composition, whole-rock chemistry and oxygen fugacities between FMQ −1.01 and FMQ −0.57 are consistent with mid-ocean ridge-type mantle. On the other hand, the AO harzburgites have slight enrichment in LREE relative to the patterns expected for residues of partial malting thereby indicating reaction with a LREE-enriched melt. Thus, their chondrite-normalized REE patterns show ‘V-shaped’ REE distributions similar to those of forearc harzburgites. The AO harzburgites have oxygen fugacities between FMQ − 1.08 and FMQ +0.72. The correlation of spinel Cr# and oxygen fugacity values indicates polygenetic association in the AO harzburgites as encountered in modern forearcs (e.g. Izu–Bonin–Mariana and South Sandwich forearc complexes). The spinel Cr# and oxygen fugacity correlation and the LREE enrichment, despite their ultra-refractory character, confirm the notion that the AO harzburgites could be residue from interaction of a previously melted mantle source (the AO spinel lherzolites) with an ascending LREE-enriched melt in a supra-subduction environment. The interaction must have caused modest melt fractions of the pre-existing mantle lithosphere. Therefore, the harzburgites experienced higher degree partial melting (17 to 25%) than the spinel lherzolites. The AO dunites, the most ‘refractory’ of the peridotites, appear to have formed at oxygen fugacities between FMQ +0.72 and FMQ +1.72, and show V-shaped REE distributions similar to those of supra-subduction zone (SSZ) dunites. Phase equilibria, field evidence and petrographic features show that the AO dunites are formed by dissolution of pyroxene from host harzburgites during the melt–mantle interaction. Focused melt flow caused the highest of melt fractions around the reaction zone. The AO podiform chromitites composed of a very refractory olivine–spinel assemblage (Fo: 94.8 and 96.1 – Cr#: 72.2–81.2%), corroborating a boninitic parentage. Therefore, the chromitites are considered to be the product of boninitic melt evolved by melt–rock interaction in a supra-subduction environment. Our results support a model involving both melt–rock interaction and differential partial melting to explain (a) precipitation of podiform chromitite from boninitic magma and (b) peridotites showing a sequence from MORB-like to subduction-related affinity.

Sub-micrometer inclusions in diamonds carry high-density fluids (HDF) from which the host diamonds have precipitated. The chemistry of these fluids is our best opportunity of characterizing the diamond-forming environment. The trace element patterns of diamond fluids vary within a limited range and are similar to those of carbonatitic/kimberlitic melts that originate from beneath the lithospheric mantle. A convecting mantle origin for the fluid is also implied by C isotopic compositions and by a preliminary Sr isotopic study (Akagi, T., Masuda, A., 1988. Isotopic and elemental evidence for a relationship between kimberlite and Zaire cubic diamonds. Nature 336, 665–667.). Nevertheless, the major element chemistry of HDFs is very different from that of kimberlites and carbonatites, varying widely and being characterized by extreme K enrichment (up to ∼ 39 wt.% on a water and carbonate free basis) and high volatile contents. The broad spectrum of major element compositions in diamond-forming fluids has been related to fluid–rock interaction and to immiscibility processes. Elemental signatures can be easily modified by a variety of mantle processes whereas radiogenic isotopes give a clear fingerprint of the time-integrated evolution of the fluid source region. Here we present the results of the first multi radiogenic-isotope (Sr, Nd, Pb) and trace element study on fluid-rich diamonds, implemented using a newly developed off-line laser sampling technique. The data are combined with N and C isotope analysis of the diamond matrix to better understand the possible sources of fluid involved in the formation of these diamonds. Sr isotope ratios vary significantly within single diamonds. The highly varied but unsupported Sr isotope ratios cannot be explained by immiscibility processes or fluid-mineral elemental fractionations occurring at the time of diamond growth. Our results demonstrate the clear involvement of a mixed fluid, with one component originating from ancient incompatible element-enriched parts of the lithospheric mantle while the trigger for releasing this fluid source was probably carbonatitic/kimberlitic melts derived from greater depths. We suggest that phlogopite mica was an integral part of the enriched lithospheric fluid source and that breakdown of this mica releases K and radiogenic Sr into a fluid phase. The resulting fluids operate as a major metasomatic agent in the sub-continental lithospheric mantle as reflected by the isotopic composition and trace element patterns of G10 garnets.

BACKGROUND: Hypoxia is as an indicator of poor treatment outcome. Consistently, hypoxic HCT116 colorectal cancer cells are resistant to oxaliplatin, although the mechanistic basis is unclear. This study sought to investigate the relative contribution of HIF-1 (hypoxia-inducible factor-1)-mediated gene expression and drug penetrance to oxaliplatin resistance using three-dimensional spheroids. METHODS: Hypoxia-inducible factor-1alpha function was suppressed by the stable expression of a dominant-negative form in HCT116 cells (DN). Cells were drug exposed as monolayer or multicellular spheroid cultures. Cells residing at differing oxygenation status were isolated from Hoechst 33342-treated spheroids using flow cytometry. Sub-populations were subjected to clonogenic survival assays and to Inductively-Coupled Plasma Mass Spectroscopy to determine oxaliplatin uptake. RESULTS: In spheroids, a sensitivity gradient (hypoxic

O 6 -Cyclohexylmethylguanine (NU2058) was developed as an inhibitor of CDK2 and was previously shown to potentiate cisplatin cytotoxicity in vitro . The aim of this study was to investigate the mechanism of cisplatin potentiation by NU2058. SQ20b, head and neck cancer cells were treated for 2 h with NU2058 (100 μM) and then for a further 2 h with cisplatin and NU2058. NU2058 increased cisplatin cytotoxicity, by clonogenic assay, with a dose modification factor (DMF) of 3.1. NU2058 increased total intracellular platinum levels 1.5-fold, and platinum–DNA adduct levels twofold. Furthermore, the cisplatin–DNA adducts formed were more toxic in the presence of NU2058. To investigate whether the effects of NU2058 on cisplatin adduct levels and toxicity were dependent on CDK2 activity, additional CDK2 inhibitors were tested. NU6230 (CDK2 IC 50 18 μM) was equipotent to NU2058 (CDK2 IC 50 17 μM) as a CDK2 inhibitor in cell-free and cell-based assays, yet did not potentiate cisplatin cytotoxicity. Furthermore, NU6102 was >1000-fold more potent than NU2058 as a CDK2 inhibitor (CDK2 IC 50 5 nM) yet was no more active than NU2058 in potentiating cisplatin. NU2058 also potentiated melphalan (DMF 2.3), and monohydroxymelphalan (1.7), but not temozolomide or ionising radiation. Whilst NU2058 increased melphalan cytotoxicity, it did not increase melphalan–DNA adduct formation. These studies demonstrate that NU2058 alters the transport of cisplatin, causing more Pt–DNA adducts, as well as sensitizing cells to cisplatin- and melphalan-induced DNA damage. However, the effects of NU2058 are independent of CDK2 inhibition.

This paper describes a technique, which allows precise and accurate Sr isotope measurement combined with trace element analysis of individual melt inclusions, of sample sizes ≪ 1 ng of Sr. The technique involves sampling by micro-milling, chemical dissolution, micro Sr column chemistry, TIMS, and ICPMS analyses. A 10% aliquot of each sample solution is used for trace element analysis by double focusing magnetic sector field ICPMS, while Sr is chemically separated from the remaining 90% and used for 87Sr/86Sr determinations by TIMS. During the development of the technique outlined above, we documented in detail the potential sources of blank contributions and their magnitude. The average size and Sr isotope composition of our laboratory total procedural blank during this study was 5.4 pg ± 0.3 pg Sr (n = 21) with an 87Sr/86Sr of 0.7111 ± 0.0002 (2SE, n = 3). The total procedural Rb blank was 1.9 ± 0.7 pg (n = 21). The total procedural blank was found to have minimal effect (

Among the Proterozoic inliers in the Istanbul Block, the lowest structural levels are exposed in the Sunnice Massif, north of Bolu. Amphibolite-facies mafic and subordinate ultramafic rocks of the Cele meta-ophiolite underlie the greenschist-facies Ediacaran calc-alkaline Yellice metavolcanics, which are intruded by the similar to 565-576 Ma Dirgine granitoids. Homblende gneisses of the Cele meta-ophiolite comprise island arc metatholeiites and transitional to calc-alkaline metabasalts which, together with minor serpentinite are disposed in a broadly antiformal structure. The meta-ophiolitic rocks are therefore the oldest ophiolites in NW Turkey, and are themselves thrust on to a putative pre-existing continental margin, now represented by the metasedimentary migmatites of the Demirci gneisses, which may thus be the oldest rocks of the complex. The Istanbul Block is an exotic terrane. Unlike other western Turkish terranes, it lacks Variscan metamorphism: its different provenance, indicated by its geological record, faunal affinities, and inherited mid-Proterozoic isotopic dates, suggests a former link with Avalonian basement in England, NW Europe and the Maritime Provinces of Canada. Hence, together with other terranes now situated further east than the Avalonian terranes of NW Europe, the Istanbul Block may represent the easternmost extremities of Avalonia, which were detached during its end-Ordovician collision with the Bruno-Silesian Promontory on the SW margin of Baltica. Subsequent migration of the Istanbul Block to its present location occurred by eastward displacement by sinistral transpression along the southern margin of Baltica to a point east of the Dobrogea and south of the Scythian Platform, followed by collision with the Sakarya Block in the Mesozoic and Late Cretaceous southward displacement with the opening of the Black Sea basin. (C) 2008 Elsevier B.V. All rights reserved.

A critical examination of the extent to which geodynamic information on the initial mantle depletion and accretion event(s) is preserved in kimberlite-borne cratonic SCLM peridotite xenoliths is attempted by using new major and trace element data of whole-rock peridotites (n = 55) sampled across the North Atlantic Craton (NAC; West Greenland). We also present additional whole-rock trace element data of mantle xenoliths from Somerset Island, the Slave and Kaapvaal cratons for comparison. Peridotites comprising the West Greenland SCLM are distinctly more olivine-rich and orthopyroxene-poor than most other cratonic peridotites, in particular those from the Kaapvaal craton. The West Greenland peridotites have higher Mg/Si but lower Al/Si, Al2O3 and CaO than cratonic mantle from the Kaapvaal Craton. We suggest that the more orthopyroxene depleted, harzburgite to dunite character of the NAC peridotites reflects more of the original melting history than peridotites from other cratons and in that sense may be more typical of cratonic lithosphere compositions prior to extensive modification. Despite this, some modal and cryptic metasomatism has clearly taken place in the West Greenland lithosphere. The insensitivity of major elements to pressure of melting at high degrees of melt extraction combined with the ease with which these elements may be changed by modal metasomatism mean that we cannot confidently constrain the depth of melting of peridotites using this approach. Mildly incompatible trace elements offer much more promise in terms of providing geodynamic information about the original Archean melting regime. The very low, systematically varying heavy REE abundances in NAC whole-rock peridotites and in peridotites from all other cratons where high-quality data are available provide ubiquitous evidence for a shallow melting regime in the absence of, or to the exhaustion of garnet. This finding explicitly excludes large extents of deep (iso- and polybaric) melting, which results in high initial garnet abundances and increasing heavy REE abundances. This evidence renders models that invoke large plume-like melting environments redundant in explaining SCLM formation and suggests broadly modern plate tectonic environments are responsible for the depletion of cratonic SCLM. A combination of the shallow melting environment and uniformly high levels of depletion indicate that melting to form the NAC lithosphere and that of other cratons probably took place in a subduction-zone environment.

Twelve road-deposited sediment samples were analyzed for platinum-group elements (PGEs) and Pb in the63 microm fraction of an urban watershed in Hawaii. Three samples were further fractionated into five size classes, from 63-125 microm to 1000-2000 microm, and these were analyzed for PGEs and Pb. Concentrations in the63 microm fraction reached 174 microg/kg (Pt), 101 microg/kg (Pd), 16 microg/kg (Rh), and 1.3 microg/kg (Ir). Enrichment ratios followed the sequence RhPt=PdIr. Iridium was geogenic in origin, while the remaining PGEs indicated significant anthropogenic contamination. Palladium, Pt and Rh concentrations and enrichment signals were consistent with PGE bivariate ratios and PGE partitioning in three-way catalysts. Size partitioning indicated that the63 microm fraction had the lowest PGE concentrations and mass loading percentages. These data suggest that autocatalyst PGE flux estimates into the environment will be significantly underestimated if only a fine grain size fraction is analyzed.

The bulk composition (major and trace elements) and the composition of minerals in peridotites of the Ortaca area, south-western Turkey, have been investigated to understand the processes controlling lithological and compositional variations in the dismembered mantle section, containing clinopyroxene-bearing harzburgite, harzburgite and dunite. The Ortaca peridotites vary from almost fertile clinopyroxene-bearing harzburgite (1.92-2.42 wt\% Al2O3, 2.00-2.64\% CaO) with a lower Cr# of the spinel phase (

Teouma, an archaeological site on Efate Island, Vanuatu, features the earliest cemetery yet discovered of the colonizers of Remote Oceania, from the late second millennium B.C. In order to investigate potential migration of seventeen human individuals, we measured isotopes of strontium (87Sr/86Sr), oxygen (δ18O), and carbon (δ13C), as well as barium (Ba) and strontium (Sr) concentrations, in tooth enamel from skeletons excavated in the first two field seasons. The majority of individuals cluster with similar isotope and Ba/Sr ratios, consistent with a diet of marine resources supplemented with plants grown on the local basaltic soils. Four outliers, with distinctive 87Sr/86Sr and δ18O, are probably immigrants, three of which were buried in a distinctive position (supine, with the head to the south) with higher Ba/Sr and δ13C, consistent with a terrestrial, nonlocal diet. Among the probable immigrants was a male buried with the crania of three of the locally raised individuals on his chest.

This study represents the first detailed investigation of platinum-group elements (PGEs) in road-deposited sediment (RDS) in Hawaii, USA. Thirty-three sample locations, in two urban watersheds in Honolulu, Oahu, Hawaii were sampled. The Pt > Pd. Iridium concentrations were uniformly low

The sediments of a small lake on Nordkinnhalvoya, Finnmark, Norway, were investigated in order to test the hypothesis that this region was sensitive to centennial–millennial climatic fluctuations during the Holocene related to changes in ocean circulation. Sedimentation at the site began during the Younger Dryas, although the site chronology, developed using a series of 14C age measurements, reveals an early Holocene hiatus in accumulation. Pollen analysis confirmed that the regional vegetation responded to Holocene climatic variability at centennial–millennial time scales and provided data used to make quantitative palaeoclimate reconstructions. The latter indicate that marked changes in seasonality characterised Holocene climatic fluctuations. Intervals with warmer summers, higher temperature sums and higher precipitation, but cooler winters and generally reduced moisture availability, alternated with intervals with cooler summers, lower temperature sums, lower precipitation, warmer winters and greater moisture availability. The former conditions were more prevalent between ca 8950 and 3950 cal BP, whereas the latter were predominant before ca 8950 and since ca 3950 cal BP. Sediment geochemistry indicates minerogenic material deposited in the lake was probably derived from two or more distinct sources or transport pathways that differed in their responses to palaeoclimatic conditions. A series of cryptotephras were located, although the small size of the shards rendered them unsuitable for electron microprobe analyses. Time-series analysis of pollen analytical and sediment geochemical data indicates that each exhibits statistically significant periodic behaviour (at periods of ca 190, 410, 1050, 1650 and 1810 yr). The periods detected suggest this behaviour may reflect regional expression of climate system responses to solar variability and/or of effects upon tides and ocean circulation of periodic lunar orbital variation. Comparison with records of fluctuations in ocean thermohaline circulation strength indicate some concordance with respect to timing of warmer and cooler intervals, but also some differences. The 8.2 ka event, that is evident in marine records from the Barents Sea, is clearly expressed by both the palaeovegetation and geochemical records. Distinctive temporal behaviour of the palaeovegetation and of different geochemical components indicates complexity in the underlying causes and mechanisms of regional climatic variability; ocean circulation variability alone cannot account for the complex climatic variability observed.

Early Cretaceous tholeiitic picrite-to-rhyolite dykes around Spitzkoppe, western Namibia, are part of the extensive Henties Bay–Outjo swarm, penecontemporaneous with 132 Ma Etendeka lavas 100 km to the NW. Although only intermediate to rhyolitic dykes contain clinopyroxene phenocrysts, the behaviour of Ca, Al and Sc in the dyke suite shows that liquidus clinopyroxene—together with olivine—was a fractionating phase when MgO fell to 9 wt %. Both a plot of CIPW normative di–hy–ol–ne–Q and modelling using (p)MELTS show that a mid-crustal pressure of 0·6 GPa is consistent with this early clinopyroxene saturation. Sr, Nd, Hf and Pb isotope variations all show trends consistent with AFC contamination (assimilation linked to fractional crystallization), involving Pan-African Damara belt continental crust. The geochemical variation, including isenthalpic AFC modelling using (p)MELTS, suggests that the picrites (olivine-rich cumulate suspensions) were interacting with granulite-facies metamorphic lower crust, the intermediate compositions with amphibolite-facies middle crust, and the rhyolitic dykes (and a few of the basalts) with the Pan-African granites of the upper crust. The calculated densities of the magmas fall systematically from picrite to rhyolite and suggest a magmatic system resembling a stack of sills throughout the crust beneath Spitzkoppe, with the storage and fractionation depth of each magma fraction controlled by its density. Elemental and isotopic features of the 20 wt % MgO picrites (including Os isotopes) suggest that their parental melts probably originated by fusion of mid-ocean ridge basalt (MORB) source convecting mantle, followed by limited reaction with sub-continental lithospheric mantle metasomatized just prior to the formation of the parental magmas. Many of the distinctive features of large-volume picritic–basaltic magmas may not be derived from their ultimate mantle sources, but may instead be the results of complex polybaric fractional crystallization and multi-component crustal contamination.

The infiltration of fluids into continental lithospheric mantle is a key mechanism for controlling abrupt changes in the chemical and physical properties of the lithospheric root, as well as diamond formation, yet the origin and composition of the fluids involved are still poorly constrained. Such fluids are trapped within diamonds when they form and so diamonds provide a unique means of directly characterizing the fluids that percolate through the deep continental lithospheric mantle. Here we show a clear chemical evolutionary trend, identifying saline fluids as parental to silicic and carbonatitic deep mantle melts, in diamonds from the Northwest Territories, Canada. Fluid-rock interaction along with in situ melting cause compositional transitions, as the saline fluids traverse mixed peridotite-eclogite lithosphere. Moreover, the chemistry of the parental saline fluids--especially their strontium isotopic compositions--and the timing of host diamond formation suggest that a subducting Mesozoic plate under western North America is the source of the fluids. Our results imply a strong association between subduction, mantle metasomatism and fluid-rich diamond formation, emphasizing the importance of subduction-derived fluids in affecting the composition of the deep lithospheric mantle.

Granitoid rocks of the southern Menderes Massif, SW Turkey include widespread possibly Ediacaran high-grade granitic orthogneisses and younger (Tertiary) sheets, sills and/or dikes of variably defo...