Sulfur loss from subducted altered oceanic crust and implications for mantle oxidation

© The Author(s), [year]. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Walters, J. B., Cruz-Uribe, A. M., & Marschall, H. R. Sulfur loss from subducted altered oceanic crust and implications for mantle oxidation. Geochemical Perspectives Letters, 13, (2020): 36-41, doi:10.7185/geochemlet.2011.Oxygen fugacity (fO2) is a controlling factor of the physics of Earth’s mantle; however, the mechanisms driving spatial and secular changes in fO2 associated with convergent margins are highly debated. We present new thermodynamic models and petrographic observations to predict that oxidised sulfur species are produced during the subduction of altered oceanic crust. Sulfur loss from the subducting slab is a function of the protolith Fe3+/ΣFe ratio and subduction zone thermal structure, with elevated sulfur fluxes predicted for oxidised slabs in cold subduction zones. We also predict bi-modal release of sulfur-bearing fluids, with a low volume shallow flux of reduced sulfur followed by an enhanced deep flux of sulfate and sulfite species, consistent with oxidised arc magmas and associated copper porphyry deposits. The variable SOx release predicted by our models both across and among active margins may introduce fO2 heterogeneity to the upper mantle.We thank James Connolly for modelling support and Peter van Keken for providing updated P–T paths for the Syracuse et al. (2010) models. The manuscript benefited from the editorial handling by Helen Williams and from constructive reviews of Maryjo Brounce, Katy Evans, and an anonymous reviewer. JBW acknowledges Fulbright and Chase Distinguished Research fellowships. This work was supported by NSF grant EAR1725301 awarded to AMC

Isotopic compositions of sulfides in exhumed high-pressure terranes: Implications for sulfur cycling in subduction zones

Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 20(7), (2019): 3347-3374, doi:10.1029/2019GC008374.Subduction is a key component of Earth's long‐term sulfur cycle; however, the mechanisms that drive sulfur from subducting slabs remain elusive. Isotopes are a sensitive indicator of the speciation of sulfur in fluids, sulfide dissolution‐precipitation reactions, and inferring fluid sources. To investigate these processes, we report δ34S values determined by secondary ion mass spectroscopy in sulfides from a global suite of exhumed high‐pressure rocks. Sulfides are classified into two petrogenetic groups: (1) metamorphic, which represent closed‐system (re)crystallization from protolith‐inherited sulfur, and (2) metasomatic, which formed during open system processes, such as an influx of oxidized sulfur. The δ34S values for metamorphic sulfides tend to reflect their precursor compositions: −4.3 ‰ to +13.5 ‰ for metabasic rocks, and −32.4 ‰ to −11.0 ‰ for metasediments. Metasomatic sulfides exhibit a range of δ34S from −21.7 ‰ to +13.9 ‰. We suggest that sluggish sulfur self‐diffusion prevents isotopic fractionation during sulfide breakdown and that slab fluids inherit the isotopic composition of their source. We estimate a composition of −11 ‰ to +8 ‰ for slab fluids, a significantly smaller range than observed for metasomatic sulfides. Large fractionations during metasomatic sulfide precipitation from sulfate‐bearing fluids, and an evolving fluid composition during reactive transport may account for the entire ~36 ‰ range of metasomatic sulfide compositions. Thus, we suggest that sulfates are likely the dominant sulfur species in slab‐derived fluids.All isotopic data and analysis locations are detailed in the supporting information accompanying this article. The authors would like to thank B. Monteleone and M. Yates for assistance with SIMS and EPMA analyses, respectively. J. Selverstone is thanked for providing samples and D. Whitney for providing additional field context. The authors would also like to thank J. Alt, C. LaFlamme, and an anonymous reviewer for their thoughtful and thorough reviews, as well as careful editorial handling by J. Blichert‐Toft. This project was funded by National Science Foundation Grant EAR 1725301 awarded to A. M. C. and a Geological Society of America grant to J. B. W.2019-12-1

Bone Morphogenetic Protein and its Option as an Alveolar Cleft Treatment

Indexación: Scopus; Scielo.Bone morphogenetic protein (BMP) is an endogenous protein that has shown significant effects in the promotion of bone formation. BMP also has been described in the reconstruction of traumatic and pathological bone defects, including alveolar cleft, alveolar ridge augmentation, maxillary sinus elevation, and applications in post-extraction alveolus graft, and peri-implant surgery among others. Despite the advantages associated with the use of BMP, currently is applied in combination with collagen matrices, which has certain properties such as low mechanical resistance and a high burst initial release that diminish its effectiveness in bone formation. In this context, the development of novel systems with greater mechanical resistance and prolonged release of BMP, that lead to chemotaxis of mesenchymal cells, following by its differentiation to osteoblasts represents a major challenge that holds outstanding clinical potential for the stimulation of bone formation. In this paper, we describe the use of BMP for the reconstruction of alveolar clefts, and its advantages being administrated in polymeric microparticles as sustain release system with promising applications in the stimulation of bone formation.http://ref.scielo.org/ps5w6

Contextos Alfareros de Interacción Social: Lo Local y Lo Foráneo en el Cementerio Inca de Quinta Normal

This paper provides information about 17 ceramic vessels, which are part of the off erings from seven burials of the Inca Period, found at the site Estación Intermodal Quinta Normal de Santiago (Chile). Based on morphologic and decorative attributes we make a stylistic classifi cation of the vessels. Additionally contextual and bioanthropological information of the burials is presented. Finally, we discuss topics related to the nature and scale of the Inca presence in the Maipo-Mapocho basin and its relationship with local groups.Key words:Tawantinsuyu, Inca pottery, Aconcagua culture, cultural dynamics.Se dan a conocer 17 vasijas cerámicas, que constituyen parte de las ofrendas de siete entierros del Período Incaico registrados en el sitio Estación Intermodal Quinta Normal de Santiago, Chile. Sobre la base de rasgos formales y decorativos de la alfarería, se realiza una adscripción estilística de estas piezas. Adicionalmente, se entrega información contextual y bioantropológica sobre los entierros. Finalmente, se discuten temáticas relacionadas con la escala y naturaleza de la presencia Incaica en la cuenca de Maipo-Mapocho, y su relación con las poblaciones locales.Palabras clave: Tawantinsuyu, Alfarería Inca, cultura Aconcagua, dinámicas de aculturación

The Consortium for Advancing Renewable Energy Technology (CARET)

The Consortium for Advancing Renewable Energy (CARET) is a research and education program which uses the theme of renewable energy to build a minority scientist pipeline. CARET is also a consortium of four universities and NASA Lewis Research Center working together to promote science education and research to minority students using the theme of renewable energy. The consortium membership includes the HBCUs (Historically Black Colleges and Universities), Fisk, Wilberforce and Central State Universities as well as Kent State University and NASA Lewis Research Center. The various stages of this pipeline provide participating students experiences with a different emphasis. Some emphasize building enthusiasm for the classroom study of science and technology while others emphasize the nature of research in these disciplines. Still others focus on relating a practical application to science and technology. And, of great importance to the success of the program are the interfaces between the various stages. Successfully managing these transitions is a requirement for producing trained scientists, engineers and technologists. Presentations describing the CARET program have been given at this year's HBCU Research Conference at the Ohio Aerospace Institute and as a seminar in the Solar Circle Seminar series of the Photovoltaic and Space Environments Branch at NASA Lewis Research Center. In this report, we will describe the many positive achievements toward the fulfillment of the goals and outcomes of our program. We will begin with a description of the interactions among the consortium members and end with a description of the activities of each of the member institutions

Oligocene niche shift, Miocene diversification – cold tolerance and accelerated speciation rates in the St. John’s Worts (Hypericum, Hypericaceae)

Background: Our aim is to understand the evolution of species-rich plant groups that shifted from tropical into cold/temperate biomes. It is well known that climate affects evolutionary processes, such as how fast species diversify, species range shifts, and species distributions. Many plant lineages may have gone extinct in the Northern Hemisphere due to Late Eocene climate cooling, while some tropical lineages may have adapted to temperate conditions and radiated; the hyper-diverse and geographically widespread genus Hypericum is one of these. Results: To investigate the effect of macroecological niche shifts on evolutionary success we combine historical biogeography with analyses of diversification dynamics and climatic niche shifts in a phylogenetic framework. Hypericum evolved cold tolerance c. 30 million years ago, and successfully colonized all ice-free continents, where today ~500 species exist. The other members of Hypericaceae stayed in their tropical habitats and evolved into ~120 species. We identified a 15–20 million year lag between the initial change in temperature preference in Hypericum and subsequent diversification rate shifts in the Miocene. Conclusions: Contrary to the dramatic niche shift early in the evolution of Hypericum most extant species occur in temperate climates including high elevations in the tropics. These cold/temperate niches are a distinctive characteristic of Hypericum. We conclude that the initial release from an evolutionary constraint (from tropical to temperate climates) is an important novelty in Hypericum. However, the initial shift in the adaptive landscape into colder climates appears to be a precondition, and may not be directly related to increased diversification rates. Instead, subsequent events of mountain formation and further climate cooling may better explain distribution patterns and species-richness in Hypericum. These findings exemplify important macroevolutionary patterns of plant diversification during large-scale global climate change

Neutrino oscillations within the induced gravitational collapse paradigm of long gamma-ray bursts

FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOThe induced gravitational collapse paradigm of long gamma-ray bursts associated with supernovae (SNe) predicts a copious neutrino-antineutrino (nu(nu) over bar) emission owing to the hypercritical accretion process of SN ejecta onto a neutron star (NS) binary companion. The neutrino emission can reach luminosities of up to 10(57) MeV. s(-1), mean neutrino energies of 20 MeV, and neutrino densities of 10(31) cm(-3). Along their path from the vicinity of the NS surface outward, such neutrinos experience flavor transformations dictated by the neutrino-to-electron-density ratio. We determine the neutrino and electron on the accretion zone and use them to compute the neutrino flavor evolution. For normal and inverted neutrino mass hierarchies and within the two-flavor formalism (nu(e)nu(x)), we estimate the final electronic and nonelectronic neutrino content after two oscillation processes: (1) neutrino collective effects due to neutrino self-interactions where the neutrino density dominates, and (2) the Mikheyev-Smirnov-Wolfenstein effect, where the electron density dominates. We find that the final neutrino content is composed by similar to 55% (similar to 62%) of electronic neutrinos, i.e., nu(e) + (nu) over bar (e), for the normal (inverted) neutrino mass hierarchy. The results of this work are the first step toward the characterization of a novel source of astrophysical MeV neutrinos in addition to core-collapse SNe and, as such, deserve further attention.8522119FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO2016/00799-7Agências de fomento estrangeiras apoiaram essa pesquisa, mais informações acesse artig