The campsite dykes: A window into the early post-solidification history of the Skaergaard Intrusion, East Greenland

publication-status: Publishedtypes: ArticleThis is an open access article.The Skaergaard Intrusion of East Greenland is cut by several generations of dykes, the earliest of which is thought to have intruded shortly after solidification of the Skaergaard. Two ~ 6 m wide doleritic dykes from the earliest generation are exposed in the campsite area near Homestead Bay of the Skaergaard Peninsula. One of the dykes (the Campsite Dyke) locally contains abundant xenoliths of troctolitic cumulate. The other (the Plagioclase-phyric Dyke) contains abundant large plagioclase phenocrysts. Cross-cutting relationships between the two dykes are not exposed. The median clinopyroxene–plagioclase–plagioclase dihedral angle, Θcpp, in the Campsite Dyke is 88–89.5°, whereas that of the Plagioclase-phyric Dyke is 79°. Using an empirical relationship between Θcpp and the duration of crystallisation derived from dolerite sills, the observed Θcpp suggests that the Campsite Dyke is the older of the two, intruding the Skaergaard when it had cooled to 920–970 °C. The Plagioclase-phyric Dyke intruded later, once the Skaergaard had cooled below 670 °C. The troctolitic xenoliths divide into two separate groups. Type A xenoliths have microstructures similar to those of the Skaergaard Layered Series although mineral compositions are generally more primitive than those of the exposed cumulates — this type of xenolith is likely to have been derived from either deeper levels in the Skaergaard Intrusion or from a closely-related underlying magma chamber. One Type A xenolith has mineral compositions and Θcpp consistent with an origin in LZb of the Layered Series — this xenolith contains partially inverted pigeonite, suggesting that inversion of low-Ca pyroxene in the lower part of the Layered Series took place after the intrusion had completely solidified. Type B xenoliths are characterized by plagioclase containing large and abundant melt inclusions. Comparison with the microstructures of glassy crystalline nodules from Iceland points to a multi-stage cooling history for Type B xenoliths, consistent with step-wise entrainment of partially crystallised material from a deep chamber. Type B xenoliths are very unlikely to have been derived from deeper levels in the Skaergaard chamber.We thank Madeleine Humphreys for her assistance in collecting samples from the Campsite area. We are grateful to Monica Price of the Oxford University Natural History Museum for access to samples from the Wager East Greenland collection, and to Christian Tegner and Kent Brooks for loan of the sample from the Campsite Dyke chill zone. John Maclennan loaned us material from Iceland and we both thank him and David Neave for interesting discussions about their microstructures. Insightful and helpful comments from Tony Morse and an anonymous reviewer greatly improved an earlier version of this contribution. QEMSCAN® is a registered trademark of FEI Company. FEI Company sponsored the QEMSCAN® analyses, which were completed by Dr Gavyn Rollinson, at Camborne School of Mines, University of Exeter, UK. This work was supported by the Natural Environment Research Council [grant numbers NE/F020325/1 and NE/J021520/1]

The Petrogenesis of the Early Permian Variscan granites of the Cornubian Batholith - lower plate post-collisional peraluminous magmatism in the Rhenohercynian Zone of SW England

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.The Early Permian Cornubian Batholith was generated during an extensional regime following Variscan convergence within the Rhenohercynian Zone of SW England. Its component granites can be classified, using mineralogical, textural and geochemical criteria, into five main types, all of which are peraluminous (A/CNK >1.1): G1 (two-mica), G2 (muscovite), G3 (biotite), G4 (tourmaline) and G5 (topaz). G1 granites formed through up to 20% muscovite and minor biotite dehydration melting of a metagreywacke source at moderate temperatures and pressures (731-806°C, >5 kbar). Younger G3 granites formed through higher temperature, lower pressure (768-847°C, <4 kbar) biotite-dominated melting of a similar source. Partial melting was strongly influenced by the progressive lower-mid crustal emplacement of mafic igneous rocks during post-Variscan extension and a minor (<5- 10%) mantle-derived component in the granites is possible. Two distinct fractionation series, G1-G2 and G3-G4, are defined using whole rock geochemical and mineral chemical data. Variations in the major elements, Ba, Sr and Rb indicate that G1 and G3 granites underwent 15-30% fractionation of an assemblage dominated by plagioclase, alkali feldspar and biotite to form, more evolved G2 and G4 granites respectively. Decreasing whole rock abundances of Zr, Th and REE support fractionation of zircon, monazite, apatite and allanite. Subsolidus alteration in G2 and G4 granites is indicated by non-primary muscovite and tourmaline and modification of major and trace element trends for G3-G4 granites, particularly for P2O5 and Rb. Topaz (G5) granites show low Zr, REE and extreme enrichment in Rb (up to 1530 ppm) and Nb (79 ppm) that cannot be related in a straightforward manner to continued differentiation of the G1-G2 or G3-G4 series. Instead, they are considered to represent partial melting, mediated by granulite facies fluids, of a biotite-rich restite following extraction of G1 and/or G3 magmas; they do not exhibit the typical geochemical characteristics of intraplate A-type granites.This study was supported by the European Regional Development Fund and European Social Fund as part of the convergence funding for Cornwall and the Isles of Scilly (Combined Universities in Cornwall project number11200NCO5), supporting a PhD for BS, and the European Union (Horizon 2020 project 641650 FAME). The Natural History Museum, London, UK are thanked for the loan of samples. We thank Richard Scrivener and Nicholas LeBoutillier for help with sampling. Steve Pendray, Sharon Uren and Joe Pickles assisted with the sample preparation and analysis. Axel Müller and Karel Breiter are thanked for discussions about topaz granites. We gratefully acknowledge Romain Tartèse and an anonymous reviewer for their constructive comments which helped to improve the manuscript

Solubility of Indium-Tin Oxide in simulated lung and gastric fluids: Pathways for human intake

ArticleThis is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.From being a metal with very limited natural distribution, indium (In) has recently become disseminated throughout the human society. Little is know of how In compounds behave in the natural environment, but recent medical studies link exposure to In compounds to elevated risk of respiratory disorders. Animal tests suggest that exposure may lead to more widespread damage in the body, notably the liver, kidneys and spleen. In this paper, we investigate the solubility of the most widely used In compound, indium-tin oxide (ITO) in simulated lung and gastric fluids in order to better understand the potential pathways for metals to be introduced into the bloodstream. Our results show significant potential for release of In and tin (Sn) in the deep parts of the lungs (artificial lysosomal fluid) and digestive tract, while the solubility in the upper parts of the lungs (the respiratory tract or tracheobronchial tree) is very low. Our study confirms that ITO is likely to remain as solid particles in the upper parts of the lungs, but that particles are likely to slowly dissolve in the deep lungs. Considering the prolonged residence time of inhaled particles in the deep lung, this environment is likely to provide the major route for uptake of In and Sn from inhaled ITO nano- and microparticles. Although dissolution through digestion may also lead to some uptake, the much shorter residence time is likely to lead to much lower risk of uptake.This paper was in part supported by the Natural Environment Research Council (NERC, NE/L001896/1). The authors benefited from advice from and discussions with Dr Adam Feldman, sample preparation and X-ray diffraction by Dr Gavyn Rollinson, and ICP- MS analysis by Sharon Uren

Platinum-group mineralization at the margin of the Skaergaard intrusion, East Greenland

This is the final version of the article. Available from Springer Verlag via the DOI in this record.Two occurrences of platinum-group elements (PGEs) along the northern margin of the Skaergaard intrusion include a sulfide-bearing gabbro with slightly less than 1 ppm PGE + Au and a clinopyroxene-actinolite-plagioclase-biotite-ilmenite schist with 16 vol% sulfide and 1.8 ppm PGE + Au. Both have assemblages of pyrrhotite, pentlandite, and chalcopyrite typical for orthomagmatic sulfides. Matching platinum-group mineral assemblages with sperrylite (PtAs2), kotulskite (Pd(Bi,Te)1–2), froodite (PdBi2), michenerite (PdBiTe), and electrum (Au,Ag) suggest a common origin. Petrological and geochemical similarities suggest that the occurrences are related to the Skaergaard intrusion. The Marginal Border Series locally displays Ni depletion consistent with sulfide fractionation, and the PGE fractionation trends of the occurrences are systematically enriched by 10–50 times over the chilled margin. The PGE can be explained by sulfide-silicate immiscibility in the Skaergaard magma with R factors of 110–220. Nickel depletion in olivine suggests that the process occurred within the host cumulate, and the low R factors require little sulfide mobility. The sulfide assemblages are different to the chalcopyrite-bornite-digenite assemblage found in the Skaergaard Layered Series and Platinova Reef. These differences can be explained by the early formation of sulfide melt, while magmatic differentiation or sulfur loss caused the unusual sulfide assemblage within the Layered Series. The PGEs indicate that the sulfides formed from the Skaergaard magma. The sulfides and PGEs could not have formed from the nearby Watkins Fjord wehrlite intrusion, which is nearly barren in sulfide. We suggest that silicate-sulfide immiscibility led to PGE concentration where the Skaergaard magma became contaminated with material from the Archean basement.The authors are grateful for logistical support from Platina Resources Ltd., Geological Survey of Denmark and Greenland, and members of the 2011 Skaergaard field team. JCØA was supported by grants from Helford Geoscience LLP and the Camborne School of Mines Trust. CT was supported by the Danish Natural Research Council and the Carlsberg Foundation, and CEL was supported by the US National Science Foundation (EAR-1019887). Samples were sectioned and prepared by Steve Pendray at Camborne School of Mines. The QEMSCAN is a registered trade mark of FEI Corporation

Geotechnical and mineralogical characterisations of marine dredged sediments before and after stabilisation to optimise their use as a road material

ArticleThis is the author accepted manuscript. The final version is available from Taylor & Francis via the DOI in this record.Dredging activities to extend, deepen and maintain access to harbours generate significant volumes of waste dredged material. Some ways are investigated to add value to these sediments. One solution described here is their use in road construction following treatment with hydraulic binders. This paper presents the characterisation of four sediments, in their raw state and after 90 days of curing following stabilisation treatment with lime and cement, using a combination of novel and established analytical techniques to investigate subsequent changes in mineralogy. These sediments are classified as fine, moderately to highly organic and highly plastic and their behaviour is linked to the presence of smectite clays. The main minerals found in the sediments using X-rays diffraction (XRD) and automated mineralogy are quartz, calcite, feldspars, aluminium silicates, pyrite and halite. Stabilisation was found to improve the mechanical performances of all the sediments. The formation of cementitious hydrates was not specifically detected using automated mineralogy or XRD. However, a decrease in the percentage volume of aluminium silicates and aluminium-iron silicates and an increase of the percentage volume of feldspars and carbonates was observed.The authors thank the all the partners having participate to the dredging operations; Lhoist and Lafarge for their technical and scientifical supports; Europe, European Regional Development Fund (ERDF), Interreg IVA and Regional Council of Basse-Normandie for their financial support to the Sustainable and Environmental Treatment And Reuse of Marine Sediment (SETARMS) project

Facial and dental alterations according to the breathing pattern

There is controversy in the literature about possible interaction of the respiratory mode with the facial and dental structures. OBJECTIVES: The aim of this study was to perform a longitudinal assessment of the changes in facial and dental structures in Angle's Class II, division 1 malocclusion individuals, divided according to the respiratory pattern (predominantly nasal or mouth), at two distinct moments of craniofacial development. MATERIAL AND METHODS: Pogonium and nose measurements were made on the lateral cephalometric tracings (LS'-Pog', LS'-B', B'-Pog', Pog'-PogTeg', Line NB, Pog-NB, N'-Prn, Prn-NPog, N-Prn-Sn, Prn-Sn-LS). Dental measurements were made on the plaster models (distances between the tips of the canine cusps and the tips of mesial cusps of the first molars) of 40 individuals aged 10 to 14 years (moment 1) and 13 to 16 years (moment 2), 23 being nose breathers (NB) and 17 being predominantly mouth breathers (MB). RESULTS: The Student's-t test and two-way ANOVA with repeated measures were applied to indicate differences between the mean values of these variables according to the moments and/or respiratory mode. CONCLUSIONS: There were alterations in the facial measurements, without interference of the breathing pattern. However, the breathing pattern infuenced dental alterations

Railway-induced ground vibrations – a review of vehicle effects

This paper is a review of the effect of vehicle characteristics on ground- and track borne-vibrations from railways. It combines traditional theory with modern thinking and uses a range of numerical analysis and experimental results to provide a broad analysis of the subject area. First, the effect of different train types on vibration propagation is investigated. Then, despite not being the focus of this work, numerical approaches to vibration propagation modelling within the track and soil are briefly touched upon. Next an in-depth discussion is presented related to the evolution of numerical models, with analysis of the suitability of various modelling approaches for analysing vehicle effects. The differences between quasi-static and dynamic characteristics are also discussed with insights into defects such as wheel/rail irregularities. Additionally, as an appendix, a modest database of train types are presented along with detailed information related to their physical attributes. It is hoped that this information may provide assistance to future researchers attempting to simulate railway vehicle vibrations. It is concluded that train type and the contact conditions at the wheel/rail interface can be influential in the generation of vibration. Therefore, where possible, when using numerical approach, the vehicle should be modelled in detail. Additionally, it was found that there are a wide variety of modelling approaches capable of simulating train types effects. If non-linear behaviour needs to be included in the model, then time domain simulations are preferable, however if the system can be assumed linear then frequency domain simulations are suitable due to their reduced computational demand

Distribution of critical metals in biotite and Li mica granite from Cornwall, UK

PublishedAnnual Winter Meetin

Separation of accessory minerals from rocks and ores by hydroseparation (HS) technology: method and application to CHR-2 chromitite, Niquelandia intrusion, Brazil

The hydroseparator embodies novel technology that can be of great benefit for the study of accessory minerals in rocks, ores, industrial products and materials of potential environmental concern. The technique is described and an example is provided of its application in the study of the platinum-bearing CHR-2 chromitite of the Niquelandia layered intrusion, central Goias, Brazil