During the past two decades significant progress has been made in understanding the origin and evolution of kimberlites, including relationships to other diamondiferous magma types such as lamproites ...and aillikites. However, the association of kimberlites and carbonatites on continental shields remains poorly understood, and two opposing ideas dominate the debate. While one school of thought argues that primary carbonatite melts transform into hybrid carbonated silicate magmas akin to kimberlites by assimilation of cratonic mantle material, others use geochemical evidence to show that carbonatite magmas can evolve from near-primary kimberlite melts within the cratonic lithosphere.
The 1.15 Ga Premier kimberlite pipe on the Kaapvaal craton in South Africa hosts several kimberlite and carbonatite dykes. Reconstructions of magma compositions suggest that up to 20 wt.% CO2 was lost from near-primary kimberlite melts during ascent through the cratonic lithosphere, but the carbonatite dyke compositions cannot be linked to the kimberlite melts via differentiation. Geochemical evidence, including mantle-like δ13C compositions, suggests that the co-occurring kimberlite and carbonatite dykes represent two discrete CO2-rich magma batches derived from a mixed source in the convecting upper mantle. The carbonatites probed a slightly more depleted source component in terms of Sr-Nd-Hf isotopic compositions relative to the peridotitic matrix that was more effectively tapped by the kimberlites (87Sr/86Sri = 0.70257 to 0.70316 for carbonatites vs. 0.70285 to 0.70546 for kimberlites; εNdi = +3.0 to +3.9 vs. +2.2 to +2.8; εHfi = -2.2 to +0.7 vs. -5.1 to -1.9).
Platinum-group element systematics suggest that assimilation of refractory lithospheric mantle material by the carbonatite melts was negligible (<1 vol.%), whereas between 5 – 35 vol.% of digested cratonic peridotite account for the kimberlite compositions, including the low 187Os/188Os signature (ƔOsi = -12.7 to -4.5). The kimberlite and carbonatite dykes show similarly strong Nd-Hf isotope decoupling (ΔεHfi = -10.7 to -7.6 vs. -8.8 to -6.1), regardless of the variable lithospheric mantle imprints. This observation suggests a common sublithospheric origin of the negative ΔεHf signature, possibly linked to ancient recycled oceanic crust components in the convecting upper mantle to transition zone sources of CO2-rich magmatism.
Mesoproterozoic kimberlite and carbonatite magmatism at Premier was coeval with subduction and collision events along the southern Kaapvaal craton margin during the 1,220 –1,090 Ma Namaqua-Natal orogeny associated with Rodinia supercontinent formation. Thermochronology suggests that the entire Kaapvaal craton was affected by this collisional tectonic event, and it appears that the changing lithospheric stress-field created pathways for deep-sourced kimberlite and carbonatite magmas to reach Earth’s surface. We find that collision-induced (e.g., Premier) and continental breakup-related (e.g., Kimberley) kimberlite magmas are compositionally indistinguishable, with the inference that plate tectonic processes aid solely in the creation of magma ascent pathways without a major influence on deep mantle melting beneath cratons. It follows that on-craton kimberlite magmatism in the hinterland of collision zones is not necessarily more likely to entrain large sublithospheric diamonds than kimberlite eruptions linked to continental breakup. This implies that Premier’s world-class endowment with ‘ultradeep’ Type-II diamonds is not causally related to its setting behind an active orogenic front.
The use of lanthanide elements for applications in various industries such as the chemical industry and in biomedical engineering is examined. Topics discussed include lanthanide nanoparticles as MRI ...contrast agents, lanthanide upconversion nanoparticles for biosensing, bioimaging, and therapy and nanoceria for nanomedicine.
The first reference on this rapidly growing topic provides an essential up-to-date guide to current and emerging trends. A group of international experts has been carefully selected by the editors to ...cover all the central aspects, with a focus on molecular species while also including industrial applications. The resulting unique overview is a must-have for researchers, both in academia and industry, who are entering or already working in the field.
In Acosta etal. (2017), a complete n-dimensional finite element analysis of the homogeneous Dirichlet problem associated to a fractional Laplacian was presented. Here we provide a comprehensive and ...simple 2D MATLAB® finite element code for such a problem. The code is accompanied with a basic discussion of the theory relevant in the context. The main program is written in about 80 lines and can be easily modified to deal with other kernels as well as with time dependent problems. The present work fills a gap by providing an input for a large number of mathematicians and scientists interested in numerical approximations of solutions of a large variety of problems involving nonlocal phenomena in two-dimensional space.
Garnet zonation provides an unparalleled record of the pressure-temperature-time-fluid evolution of metamorphic rocks. At extreme temperature conditions >900 °C, however, most elements preserve ...little zonation due to intracrystalline diffusional relaxation. Under these conditions, slowly diffusing trace elements including P, Na, and Ti have the best chance of recording metamorphic histories. Here we map dramatic zoning patterns of these elements in subducted high-pressure felsic granulite (Saxon Granulite Massif) and ultrahigh-pressure diamondiferous "saidenbachite" (Saxonian Erzgebirge, Bohemian Massif). The results show that garnet replacement via interface coupled dissolution-reprecipitation can strongly affect garnet compositions in subduction zones and that P, Na, and Ti record burial and exhumation histories that are otherwise lost to diffusion. In these samples, P diffuses the slowest, and Ti the fastest.
The rare earths (REs) are a family of 17 elements that exhibit pronounced chemical similarities as a group, while individually expressing distinctive and varied electronic properties. These atomistic ...electronic properties are extraordinarily useful and motivate the application of REs in many technologies and devices. From their discovery to the present day, a major challenge faced by chemists has been the separation of RE elements, which has evolved from tedious crystallization to highly engineered solvent extraction schemes. The increasing incorporation and dependence of REs in technology have raised concerns about their sustainability and motivated recent studies for improved separations to achieve a circular RE economy.
Three synthetic reference glasses were prepared by directly fusing and stirring 3.8 kg of high‐purity oxide powders to provide reference materials for microanalytical work. These glasses have ...andesitic major compositions and are doped with fifty‐four trace elements in nearly identical abundance (500, 50, 5 µg g−1) using oxide powders or element solutions, and are named ARM‐1, 2 and 3, respectively. We further document that sector‐field (SF) ICP‐MS (Element 2 or Element XR) is capable of sweeping seventy‐seven isotopes (from 7Li to 238U, a total of sixty‐eight elements) in 1 s and, thus, is able to quantify up to sixty‐eight elements by laser sampling. Micro‐ and bulk analyses indicate that the glasses are homogeneous with respect to major and trace elements. This paper provides preliminary data for the ARM glasses using a variety of analytical techniques (EPMA, XRF, ICP‐OES, ICP‐MS, LA‐Q‐ICP‐MS and LA‐SF‐ICP‐MS) performed in ten laboratories. Discrepancies in the data of V, Cr, Ni and Tl exist, mainly caused by analytical limitations. Preliminary reference and information values for fifty‐six elements were calculated with uncertainties 2 relative standard error (RSE) estimated in the range of 1–20%.
Key Points
Three synthetic andesite reference glasses (ARM‐1, ARM‐2 and ARM‐3) were prepared, and characterised by a variety of analytical techniques.
The homogeneity of the ARM glasses was evaluated by multiple EPMA and LA‐ICP‐MS spot analyses on randomly selected glass splits.
Preliminary reference values of the ARM glasses are provided.
A simple and low-cost tandem sulfonylation/cyclization of 1,5-diene, aryldiazonium salt, and DABCO·(SO2)2 is disclosed. This base-promoted multicomponent reaction can provide a “green” and economic ...synthesis of sulfonylated pyrrolidones under transition-metal-free and moisture/oxygen-insensitive reaction conditions, thus delivering a wide range of sulfonylated pyrrolidones in moderate to high yields with excellent functional group compatibility. A plausible mechanism involving a radical process is proposed, which demonstrates highly chemoselective trapping of the aryl radical with “SO2” species, and a regioselective sulfonylation/cyclization protocol in this reaction.
Long non-coding RNAs (lncRNAs) have become increasingly important in the past decade. They are known to regulate gene expression and to interact with chromatin, proteins and other coding and ...non-coding RNAs. The study of lncRNAs has been challenging due to their low expression and the lack of tools developed to adapt to their particular features. Studies on lncRNAs performed to date have largely focused on cellular functions, whereas details on the mechanism of action has only been thoroughly investigated for a small number of lncRNAs. Nevertheless, some studies have highlighted the potential of these transcripts to contain functional domains, following the same accepted trend as proteins. Interestingly, many of these identified “domains” are attributed to functional units derived from transposable elements. Here, we review several types of functions of lncRNAs and relate these functions to lncRNA-embedded transposable elements.
•Transposable elements (TEs) are prevalent in lncRNAs•LncRNA embedded-TEs regulate lncRNA expression, localization and tissue specificity•TEs are functional domains of lncRNAs•LncRNA sequence analysis would benefit from systematic TE annotation
Mobile genetic elements (MGEs) contribute to bacterial adaptation and evolution; however, high-throughput, unbiased MGE detection remains challenging. We describe MGEfinder, a bioinformatic toolbox ...that identifies integrative MGEs and their insertion sites by using short-read sequencing data. MGEfinder identifies the genomic site of each MGE insertion and infers the identity of the inserted sequence. We apply MGEfinder to 12,374 sequenced isolates of 9 prevalent bacterial pathogens, including Mycobacterium tuberculosis, Staphylococcus aureus, and Escherichia coli, and identify thousands of MGEs, including candidate insertion sequences, conjugative transposons, and prophage elements. The MGE repertoire and insertion rates vary across species, and integration sites often cluster near genes related to antibiotic resistance, virulence, and pathogenicity. MGE insertions likely contribute to antibiotic resistance in laboratory experiments and clinical isolates. Additionally, we identified thousands of mobility genes, a subset of which have unknown function opening avenues for exploration. Future application of MGEfinder to commensal bacteria will further illuminate bacterial adaptation and evolution.
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•Introduces MGEfinder, a bioinformatic toolbox to detect MGE integrations•Describes the MGE repertoire, from small repeats to prophages, of 9 pathogens•MGE insertions affect antibiotic resistance, virulence, pathogenicity across species
Microbes evolve through DNA mutations and by the transfer of mobile genetic elements (MGEs). In this study, Durrant et al. describe MGEfinder, a tool that enables MGE localization and characterization. Using MGEfinder, they analyze 9 bacterial pathogens, providing insights into how MGEs might affect antibiotic resistance, virulence, and pathogenicity.
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