116 research outputs found

    Timing and Petrogenesis of the Permo-Carboniferous Larvik Plutonic Complex, Oslo Rift, Norway : New Insights from U-Pb, Lu-Hf, and O Isotopes in Zircon

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    The Permo-Carboniferous Oslo Rift is a narrow, aborted continental rift with comparatively little extension but voluminous magmatism, developed at a Proterozoic lithospheric discontinuity. On the southern flank of the onshore part of the rift, the multiple intrusive phase Larvik plutonic complex (LPC) encompasses almost the width of the rift with a conspicuous over- to undersaturated assemblage of monzonite (larvikite, tonsbergite) and nepheline syenite (lardalite, foyaite). We present new single-crystal U-Pb-, Lu-Hf-, and O-in-zircon isotope data for the intrusive centers of the complex. U-Pb ages of slightly over- to undersaturated monzonites show a shift in igneous activity from 299 Ma on the eastern edge of the complex to 289 Ma in the west. The western part of the complex is built of two consanguineous magmatic systems with a northward shift in the locus of magmatism, from 296 to 289 Ma (undersaturated monzonite) and 296 to similar to 288 Ma (nepheline syenite). Moreover, an early oversaturated monzonite was emplaced in the eastern part of the complex at similar to 302 Ma. The Hf and O isotope composition of the monzonites and nepheline syenites shows little variation with zircon epsilon(Hf) (295 Ma) values of +5.5 to +8 and delta(18)Omicron values of +4.79 parts per thousand to +5.49 parts per thousand. No change in isotope values is observed with varying alkalinity and the Hf and O isotope compositions are interpreted as mantle source values. The source of the precursors of the monzonitic and nepheline syenitic magmas was probably a mildly depleted, sublithospheric peridotite in the lithosphere-asthenosphere boundary zone (at 3-4 GPa). Rhyolite-MELTS modeling implies polybaric fractionation of weakly alkaline basaltic melts from the source having led to an oversaturated/saturated liquid line of descent at similar to 0.5 GPa and an undersaturated one at similar to 1 GPa. Magmatism had an imperative role in the evolution of the rift by localizing strain and weakening the lithosphere along the discontinuity. A fractionating crustal melt column was tapped at varying depths in the course of advancing rupturing with no significant mixing of the over- and undersaturated melts, and magma batches were emplaced as sequential nested plutons in response to differential opening of the rift. Among continental saturated-undersaturated alkaline complexes, the LPC may be unique in the emplacement of successive magma batches across a continental rift in the direction of opening, tapping of increasingly deeper parts of the melt column with advancing rifting, and intrusion of two contemporaneous, contrasting magmatic lineages at the end of igneous activity. The marked lithospheric step at the rift locus in the Precambrian basement of southeastern Norway was probably the driving force for the inception and evolution of the Larvik magmatic system.Peer reviewe

    Periodicity of Karoo rift zone magmatism inferred from zircon ages of silicic rocks : Implications for the origin and environmental impact of the large igneous province

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    New U-Pb ages for zircons constrain the duration of silicic magmatism and timing of coeval mafic magmatism across the main rift zone of the Karoo large igneous province in Mozambique. Our 190 ± 2 Ma, 188.4 ± 0.9 Ma, 181.7 ± 1.0 Ma, 180 ± 3 Ma, 178 ± 2 Ma and 172 ± 2 Ma ages support periodicity of Karoo magmatism previously inferred from 40Ar/39Ar age data. The ∼ 190–188 Ma ages confirm early onset of magmatism and the ∼ 182–178 Ma ages correlate the bimodal volcanic successions of the Lower Zambezi and the Movene Formation with widespread silicic magmatism across the rift zone. The ∼ 172 Ma age corresponds to waning magmatic activity. The age range and Hf isotopic compositions of zircons indicate up to ∼9 Ma lifespan for the Jurassic silicic magma chambers and suggest that the ∼2700–400 Ma xenocrysts represent crustal sources of the host rocks. The available chronological data indicate that the ∼183 Ma main phase magmatism was largely confined within the main Karoo and Kalahari basins and that the preceding and subsequent phases were mainly associated with the Karoo rift zone. Judging from geochemical literature, different kinds of magmas were erupted during the successive magmatic phases. We calculate from published geochemical data that the mafic main phase mag- mas were relatively poor in CO2 and SO2 and the lava stacking patterns point to low eruption rates, which suggests that degassing of sedimentary wall-rocks of intrusions probably triggered the coeval Pliensbachian-Toarcian extinction. In contrast, the mafic late phase magmas were rich in CO2 and SO2 and at least some of the lavas indicate high eruption rates. We propose that efficient degassing from widespread mafic magmatism and explosive eruption of over 30,000 km3 of silicic magmas in the Karoo rift zone linked the ∼182–178 Ma late phase magmatism with contemporaneous global biosphere crises.New U-Pb ages for zircons constrain the duration of silicic magmatism and timing of coeval mafic magmatism across the main rift zone of the Karoo large igneous province in Mozambique. Our 190 +/- 2 Ma, 188.4 +/- 0.9 Ma, 181.7 +/- 1.0 Ma, 180 +/- 3 Ma, 178 +/- 2 Ma and 172 +/- 2 Ma ages support periodicity of Karoo magmatism previously inferred from 40Ar/39Ar age data. The - 190-188 Ma ages confirm early onset of magmatism and the - 182-178 Ma ages correlate the bimodal volcanic successions of the Lower Zambezi and the Movene Formation with widespread silicic magmatism across the rift zone. The - 172 Ma age corresponds to waning magmatic activity. The age range and Hf isotopic compositions of zircons indicate up to -9 Ma lifespan for the Jurassic silicic magma chambers and suggest that the -2700-400 Ma xenocrysts represent crustal sources of the host rocks. The available chronological data indicate that the -183 Ma main phase magmatism was largely confined within the main Karoo and Kalahari basins and that the preceding and subsequent phases were mainly associated with the Karoo rift zone. Judging from geochemical literature, different kinds of magmas were erupted during the successive magmatic phases. We calculate from published geochemical data that the mafic main phase magmas were relatively poor in CO2 and SO2 and the lava stacking patterns point to low eruption rates, which suggests that degassing of sedimentary wall-rocks of intrusions probably triggered the coeval Pliensbachian-Toarcian extinction. In contrast, the mafic late phase magmas were rich in CO2 and SO2 and at least some of the lavas indicate high eruption rates. We propose that efficient degassing from widespread mafic magmatism and explosive eruption of over 30,000 km3 of silicic magmas in the Karoo rift zone linked the -182-178 Ma late phase magmatism with contemporaneous global biosphere crises. (c) 2022 The Authors. Published by Elsevier B.V. on behalf of International Association for Gondwana Research. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/ 4.0/).Peer reviewe

    The Snf2 Homolog Fun30 acts as a homodimeric ATP-dependent chromatin-remodeling enzyme

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    The Saccharomyces cerevisiae Fun30 (Function unknown now 30) protein shares homology with an extended family of Snf2-related ATPases. Here we report the purification of Fun30 principally as a homodimer with a molecular mass of about 250 kDa. Biochemical characterization of this complex reveals that it has ATPase activity stimulated by both DNA and chromatin. Consistent with this, it also binds to both DNA and chromatin. The Fun30 complex also exhibits activity in ATP-dependent chromatin remodeling assays. Interestingly, its activity in histone dimer exchange is high relative to the ability to reposition nucleosomes. Fun30 also possesses a weakly conserved CUE motif suggesting that it may interact specifically with ubiquitinylated proteins. However, in vitro Fun30 was found to have no specificity in its interaction with ubiquitinylated histones

    Ancient volcanism on the Moon: Insights from Pb isotopes in the MIL 13317 and Kalahari 009 lunar meteorites

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    Lunar meteorites provide a potential opportunity to expand the study of ancient (>4000 Ma) basaltic volcanism on the Moon, of which there are only a few examples in the Apollo sample collection. Secondary Ion Mass Spectrometry (SIMS) was used to determine the Pb isotopic compositions of multiple mineral phases (Ca-phosphates, baddeleyite K-feldspar, K-rich glass and plagioclase) in two lunar meteorites, Miller Range (MIL) 13317 and Kalahari (Kal) 009. These data were used to calculate crystallisation ages of 4332 ±2Ma (95% confidence level) for basaltic clasts in MIL 13317, and 4369 ±7Ma (95% confidence level) for the monomict basaltic breccia Kal 009. From the analyses of the MIL 13317 basaltic clasts, it was possible to determine an initial Pb isotopic composition of the protolith from which the clasts originated, and infer a 238U/204Pb ratio (μ-value) of 850 ±130(2σ uncertainty) for the magmatic source of this basalt. This is lower than μ-values determined previously for KREEP-rich (an acronym for K, Rare Earth Elements and P) basalts, although analyses of other lithological components in the meteorite suggest the presence of a KREEP component in the regolith from which the breccia was formed and, therefore, a more probable origin for the meteorite on the lunar nearside. It was not possible to determine a similar initial Pb isotopic composition from the Kal 009 data, but previous studies of the meteorite have highlighted the very low concentrations of incompatible trace elements and proposed an origin on the farside of the Moon. Taken together, the data from these two meteorites provide more compelling evidence for widespread ancient volcanism on the Moon. Furthermore, the compositional differences between the basaltic materials in the meteorites provide evidence that this volcanism was not an isolated or localised occurrence, but happened in multiple locations on the Moon and at distinct times. In light of previous studies into early lunar magmatic evolution, these data also imply that basaltic volcanism commenced almost immediately after Lunar Magma Ocean (LMO) crystallisation, as defined by Nd, Hf and Pb model ages at about 4370Ma

    Economic impact of Tegaderm chlorhexidine gluconate (CHG) dressing in critically ill patients.

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    PURPOSE: To estimate the economic impact of a Tegaderm(TM) chlorhexidine gluconate (CHG) gel dressing compared with a standard intravenous (i.v.) dressing (defined as non-antimicrobial transparent film dressing), used for insertion site care of short-term central venous and arterial catheters (intravascular catheters) in adult critical care patients using a cost-consequence model populated with data from published sources. MATERIAL AND METHODS: A decision analytical cost-consequence model was developed which assigned each patient with an indwelling intravascular catheter and a standard dressing, a baseline risk of associated dermatitis, local infection at the catheter insertion site and catheter-related bloodstream infections (CRBSI), estimated from published secondary sources. The risks of these events for patients with a Tegaderm CHG were estimated by applying the effectiveness parameters from the clinical review to the baseline risks. Costs were accrued through costs of intervention (i.e. Tegaderm CHG or standard intravenous dressing) and hospital treatment costs depended on whether the patients had local dermatitis, local infection or CRBSI. Total costs were estimated as mean values of 10,000 probabilistic sensitivity analysis (PSA) runs. RESULTS: Tegaderm CHG resulted in an average cost-saving of £77 per patient in an intensive care unit. Tegaderm CHG also has a 98.5% probability of being cost-saving compared to standard i.v. dressings. CONCLUSIONS: The analyses suggest that Tegaderm CHG is a cost-saving strategy to reduce CRBSI and the results were robust to sensitivity analyses

    Current and wave effects around windfarm monopile foundations

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    publisher: Elsevier articletitle: Current and wave effects around windfarm monopile foundations journaltitle: Coastal Engineering articlelink: http://dx.doi.org/10.1016/j.coastaleng.2017.01.003 content_type: article copyright: © 2017 Elsevier B.V. All rights reserved

    Scale-up of Digital Innovations in Health Care: Expert Commentary on Enablers and Barriers

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    Health care delivery is undergoing a rapid change from traditional processes toward the use of digital health interventions and personalized medicine. This movement has been accelerated by the COVID-19 crisis as a response to the need to guarantee access to health care services while reducing the risk of contagion. Digital health scale-up is now also vital to achieve population-wide impact: it will only accomplish sustainable effects if and when deployed into regular health care delivery services. The question of how sustainable digital health scale-up can be successfully achieved has, however, not yet been sufficiently resolved. This paper identifies and discusses enablers and barriers for scaling up digital health innovations. The results discussed in this paper were gathered by scientists and representatives of public bodies as well as patient organizations at an international workshop on scaling up digital health innovations. Results are explored in the context of prior research and implications for future work in achieving large-scale implementations that will benefit the population as a whole

    Expert Commentary on Enablers and Barriers

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    ©Hannes Schlieter, Lisa A Marsch, Diane Whitehouse, Lena Otto, Ana Rita Londral, Gisbert Wilhelm Teepe, Martin Benedict, Joseph Ollier, Tom Ulmer, Nathalie Gasser, Sabine Ultsch, Bastian Wollschlaeger, Tobias Kowatsch. Originally published in the Journal of Medical Internet Research (https://www.jmir.org), 11.03.2022.Health care delivery is undergoing a rapid change from traditional processes toward the use of digital health interventions and personalized medicine. This movement has been accelerated by the COVID-19 crisis as a response to the need to guarantee access to health care services while reducing the risk of contagion. Digital health scale-up is now also vital to achieve population-wide impact: it will only accomplish sustainable effects if and when deployed into regular health care delivery services. The question of how sustainable digital health scale-up can be successfully achieved has, however, not yet been sufficiently resolved. This paper identifies and discusses enablers and barriers for scaling up digital health innovations. The results discussed in this paper were gathered by scientists and representatives of public bodies as well as patient organizations at an international workshop on scaling up digital health innovations. Results are explored in the context of prior research and implications for future work in achieving large-scale implementations that will benefit the population as a whole.publishersversionpublishe

    Jurassic high heat production granites associated with the Weddell Sea rift system, Antarctica.

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    The distribution of heat flow in Antarctic continental crust is critical to understanding continental tectonics, ice sheet growth and subglacial hydrology. We identify a group of High Heat Production granites, intruded into upper crustal Palaeozoic metasedimentary sequences, which may contribute to locally high heat flow beneath the West Antarctic Ice Sheet. Four of the granite plutons are exposed above ice sheet level at Pagano Nunatak, Pirrit Hills, Nash Hills and Whitmore Mountains. A new Usingle bondPb zircon age from Pirrit Hills of 178.0 ± 3.5 Ma confirms earlier Rbsingle bondSr and Usingle bondPb dating and that the granites were emplaced approximately coincident with the first stage of Gondwana break-up and the developing Weddell rift, and ~ 5 m.y. after eruption of the Karoo-Ferrar large igneous province. Aerogeophysical data indicate that the plutons are distributed unevenly over 40,000 km2 with one intruded into the transtensional Pagano Shear Zone, while the others were emplaced within the more stable Ellsworth-Whitmore mountains continental block. The granites are weakly peraluminous A-types and have Th and U abundances up to 60.7 and 28.6 ppm respectively. Measured heat production of the granite samples is 2.96–9.06 μW/m3 (mean 5.35 W/m3), significantly higher than average upper continental crust and contemporaneous silicic rocks in the Antarctic Peninsula. Heat flow associated with the granite intrusions is predicted to be in the range 70–95 mW/m2 depending on the thickness of the high heat production granite layer and the regional heat flow value. Analysis of detrital zircon compositions and ages indicates that the high Th and U abundances are related to enrichment of the lower-mid crust that dates back to 200–299 Ma at the time of the formation of the Gondwanide fold belt and its post-orogenic collapse and extension
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