Tracing alteration of ultramafic rocks in the Samail ophiolite

Alteration of ultramafic rocks is ubiquitous to their occurrence near the surface. Primary mantle minerals like olivine and pyroxenes are unstable at low pressure and temperatures and undergo hydration (serpentinization), carbonation and weathering reactions forming hydrated and carbonated minerals. Employing a variety of analytical techniques including: electron microprobe, X-Ray diffraction, major and trace element geochemistry, Mg isotopes geochemistry and geochemical modelling this work seeks to contrain conditions ofa lteration and trace changes in composition of peridotite during alteration. In Wadi Fins in the southeast of Oman peridotites outcrop at the bottom of a canyon overlaid by a thick sequence 1.5 km of Cretaceous to Eocene shallow oceanic limestones and dolostones. The peridotites exhibit different types of alteration. While the common view is that serpentinization and carbonation of peridotites is isochemical this is not the case for alteration in Wadi Fins. Peridotites tens of meters below the unconformity are characterized by a striking grid of carbonate and serpentine veins. The calcite veins and relatively low MgO/SiO2 suggest that the peridotites reacted with a hydrous fluid derived from interaction of seawater with the overlying sediments composed of limestones with minor amounts of chert. This is further affirmed by average δ13C, δ18O and 87Sr/86Sr from carbonate veins in the peridotites that are similar to values of the sediments. Clumped isotope thermometry on calcite veins in peridotite establish that they formed at 25–60 ℃. Reaction path modeling of carbonate- quartz derived fluids with peridotite reproduces the observed mineral assemblage composed of carbonate and serpentine with similar Mg and MgO/SiO2 at high water to rock ratios, with carbon, H2O and silica added to the rock by the reacting fluid. Close to the unconformity the altered peridotites are characterized by concentric alteration halos recording variable fO2 and fS2. The partially serpentinized cores preserved primary minerals and record extremely low oxygen fugacities (fO2~10^(-75) bars). Two alteration zones are present evident from the alteration color. These zones exhibit nonisochemical alteration characterized by intergrowths of stevensite/lizardite. The alteration zones record progressively higher (fO2) recorded by Ni-rich sulfides and iron oxides/hydroxides. The alteration zones lost 20-30% of their initial magnesium content, together with mobilization of iron over short distances from inner green zones into outer red zones, where iron was reprecipitated in goethite intermixed with silicates due to higher fO2. The loss of magnesium in this peridotites motivated the final section of work. Mg isotopic compositions of partially serpentinized harzburgites and dunites in Oman are identical to average mantle and bulk silicate Earth (δ26Mg=-0.25‰) while altered periodites from Wadi Fins get heavier with increasing alteration. Analyses of peridotite alteration products including samples from Wadi Fins and carbonates from Wadi Tayin were used to show that isochemical serpentinization at low W/R does not fractionate Mg isotopes. I propose a mechanism that with increasing W/R and co-precipitation of Mg-carbonates and serpentine leads to carbonates with light isotopic compositions (Magnesite δ26Mg =-3.3 and dolomite δ26Mg=-1.91) and serpentine with heavy compositions (up to δ26Mg =-0.96 in serpentine veins). This complementary enrichment-depletion and the finite 14C ages of the carbonates suggest that serpentinization is ongoing along carbonation in Oman at ambient temperatures. Rates of calcite precipitation in travertines inferred from Δ26Mgcal-fl suggest that travertine formation in Oman sequesters a total of 10^6-10^7 kg CO2/yr

A Mg isotopic perspective on the mobility of magnesium during serpentinization and carbonation of the Oman Ophiolite

Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 126(2), (2021): e2020JB020237, https://doi.org/10.1029/2020JB020237.Alteration of mantle peridotite in the Samail ophiolite forms secondary minerals, mainly serpentine and Mg‐rich carbonates. Magnesium accounts for ∼25 – 30% of peridotite mass and its mobility can be used to trace this alteration. We report the first set of Mg isotope measurements from peridotites and their alteration products in Oman. Partially serpentinized peridotites have Mg isotope ratios that are indistinguishable from estimates for the average mantle and bulk silicate earth (δ26Mg = −0.25 ± 0.04‰). However, more extensively altered peridotite samples show large shifts in Mg isotopic composition. The range of δ26Mg values for our suite of alteration products from the mantle section is ∼4.5‰ (from −3.39‰ to 1.19‰), or >60% of the total range of terrestrial variability in δ26Mg values. Serpentine veins are typically enriched in 26Mg (max δ26Mg value = 0.96‰) whereas Mg‐carbonate veins are associated with low 26Mg/24Mg ratios (magnesite δ26Mg = −3.3‰, dolomite δ26Mg = −1.91‰). Our preferred explanation for the range in δ26Mg values involves coprecipitation of serpentine and carbonates at water‐to‐rock ratios >103. The coincidence of alteration products characterized by δ26Mg values that are both lower and higher than bulk silicate Earth and the finite 14C ages of the carbonates suggest that both serpentinization and carbonation are ongoing in Oman. Rates of calcite precipitation in travertines inferred from Δ26Mgcal‐fl suggest that travertine formation in Oman sequesters a total of 106–107 kg CO2/yr, consistent with previous estimates.This work was supported through the Sloan Foundation–Deep Carbon Observatory (Grant 2014‐3‐01, Kelemen PI), the U.S.‐National Science Foundation (NSF‐EAR‐1516300, Kelemen lead PI).2021-06-0

Timing of magnetite growth associated with peridotite-hosted carbonate veins in the SE Samail ophiolite, Wadi Fins, Oman

Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 125(5), (2020): e2019JB018632, doi:10.1029/2019JB018632.Carbonate‐altered peridotite are common in continental and oceanic settings and it has been suggested that peridotite‐hosted carbonate represent a significant component of the carbon‐cycle and provide an important link in the CO2 dynamics between the atmosphere, hydrosphere, and lithosphere. The ability to constrain the timing of carbonate and accessory phase growth is key to interpreting the mechanisms that contribute to carbonate alteration, veining, and mineralization in ultramafic rocks. Here we examine a mantle section of the Samail ophiolite exposed in Wadi Fins in southeastern Oman where the peridotite is unconformably overlain by Late Cretaceous‐Paleogene limestone and crosscut by an extensive network of carbonate veins and fracture‐controlled alteration. Three previous 87Sr/86Sr measurements on carbonate vein material in the peridotite produce results consistent with vein formation involving Cretaceous to Eocene seawater (de Obeso & Kelemen, 2018, https://doi.org/10.1098/rsta.2018.0433). We employ (U‐Th)/He chronometry to constrain the timing of hydrothermal magnetite in the calcite veins in the peridotite. Magnetite (U‐Th)/He ages of crystal sizes ranging from 1 cm to 200 μm record Miocene growth at 15 ± 4 Ma, which may indicate (1) fluid–rock interaction and carbonate precipitation in the Miocene, or (2) magnetite (re)crystallization within pre‐existing veins. Taken together with published Sr‐isotope values, these results suggest that carbonate veining at Wadi Fins started as early as the Cretaceous, and continued in the Miocene associated with magnetite growth. The timing of hydrothermal magnetite growth is coeval with Neogene shortening and faulting in southern Oman, which points to a tectonic driver for vein (re)opening and fluid‐rock alteration.This research was supported by a National Science Foundation (NSF) Graduate Research Fellowship to E.H.G. Cooperdock, the UTChron Laboratory at The University of Texas at Austin, the Chevron (Gulf) Centennial Professorship to D.F. Stockli, and by a Sloan Foundation grant awarded to P.B. Kelemen. We are grateful to Desmond Patterson for assistance and training with He measurements and data reduction, to Jessie Maisano for technical support with the X‐Ray Computed Tomography. These data and images were produced at the High‐Resolution X‐ray Computed Tomography Facility of the University of Texas at Austin. EHGC is grateful to Jaime Barnes, Richard Ketcham, Frieder Klein and Othmar Müntener for helpful comments on an earlier version of this manuscript. Thank you to Fin Stuart and Uwe Ring for their helpful reviews, and Stephen Parman for feedback and editorial handling of the manuscript. The (U‐Th)/He data in this manuscript are available in the GeoChron repository (https://www.geochron.org) and sample IGSNs are in the SESAR database (http://www.geosamples.org).2020-10-0

Remote Monitoring of Treatment Response in Parkinson's Disease: The Habit of Typing on a Computer

The recent advances in technology are opening a new opportunity to remotely evaluate motor features in people with Parkinson's disease (PD). We hypothesized that typing on an electronic device, a habitual behavior facilitated by the nigrostriatal dopaminergic pathway, could allow for objectively and nonobtrusively monitoring parkinsonian features and response to medication in an at-home setting.This study was conducted with research funds from Michael J. Fox Foundation for Parkinson's Research Grant 10860.Peer reviewe

Deep Sourced Fluids for Peridotite Carbonation in the Shallow Mantle Wedge of a Fossil Subduction Zone: Sr and C Isotope Profiles of OmanDP Hole BT1B

金沢大学理工研究域地球社会基盤学系Completely carbonated peridotites represent a window to study reactions of carbon-rich fluids with mantle rocks. Here, we present details on the carbonation history of listvenites close to the basal thrust in the Samail ophiolite. We use samples from Oman Drilling Project Hole BT1B, which provides a continuous record of lithologic transitions, as well as outcrop samples from listvenites, metasediments, and metamafics below the basal thrust of the ophiolite. 87Sr/86Sr of listvenites and serpentinites, ranging from 0.7090 to 0.7145, are significantly more radiogenic than mantle values, Cretaceous seawater, and other peridotite hosted carbonates in Oman. The Hawasina sediments that underlie the ophiolite, on the other hand, show higher 87Sr/86Sr values of up to 0.7241. δ13C values of total carbon in the listvenites and serpentinites range from −10.6‰ to 1.92‰. We also identified a small organic carbon component with δ13C as low as −27‰. Based on these results, we propose that during subduction at temperatures above >400°C, carbon-rich fluids derived from decarbonation of the underlying sediments migrated updip and generated the radiogenic 87Sr/86Sr signature and the fractionated δ13C values of the serpentinites and listvenites in core BT1B. © 2021. American Geophysical Union. All Rights Reserved

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Alternativas de financiamiento para las pequeñas y medianas empresas en la costa sur de Jalisco

El objetivo de este estudio consistió en identificar las alternativas de financiamiento que existen para las pequeñas y medianas empresas (PyMES) en la costa sur de Jalisco. Se identificó las características de estos financiamientos en cada institución, aspectos como la tasa de interés, plazo proporcionado para liquidar el crédito, documentación requerida y metas existentes que cada organismo utiliza para la colocación de créditos, entre otras variables. El estudio comprendió el análisis de 14 instituciones financieras que incluyó bancos comerciales, cajas populares, instituciones gubernamentales e instituciones encargadas de proporcionar crédito a empresarios con bajos recursos. La información se recopiló a través de un cuestionario estructurado aplicado en forma de entrevistas directas, se analizó con cuadros de distribución de frecuencias y la prueba no paramétrica de chi cuadrado X2 para la asociación de variables

Lithological information, strontium, rubidium and carbon concentrations and Sr and C isotope data of samples from OmanDP Hole BT1B (Semail ophiolite; ICDP Oman drilling project)

This database provides measurements on 87Sr/86Sr, d13C from samples of Oman Drilling Project Hole BT1B. The database includes listvenites (n=50), serpentinites (n=14), metamorphic sole rocks (n=11). The sample names and grouping by Units were determined on-board D/V Chikyu from macroscopic observations (Visual Core Description; Kelemen et al. [2020]). Rb and Sr concentrations were determined using a Quadrupole Inductively-Coupled-Plasma-Mass Spectrometer (Q-ICP-MS) at the University of Montpellier (France) and were originally reported by Godard et al. (2021). 87Sr/86Sr were analyzed for interspersed with US National Institute of Standards and Technology (NIST) SRM 987 on a Thermo Scientific Neptune multi-collector ICP-MS at Lamont Doherty Earth Observatory (United States). Total Carbon (TC) was measured from the same bulk rock powder splits as for Strontium isotopes. Total Organic Carbon (TOC, or reduced carbon) was measured from the residual rock powder after the removal of Inorganic Carbon (carbonate carbon) through reaction with dilute (3 N) HCl for at least 3 days, followed by washing with Millipore® water. Concentrations and d13C ratios of Total Carbon (TC) and Total Organic Carbon (TOC), were determined using a Costech element analyzer coupled with a Thermo Scientific Delta V plus mass spectrometer at Lamont Doherty Earth Observatory (United States). References: Reference : Kelemen, P. B., J. M. Matter, D. A. H. Teagle, J. A. Coggon, and the Oman Drilling Project Science Team (2020), Proceedings of the Oman Drilling Project, College Station, TX. and Godard, Marguerite; Carter, Elliot; Decrausaz, Thierry; Lafay, Romain; Bennett, Emma; Kourim, Fatma; de Obeso, Juan-Carlos; Michibayashi, Katsuyoshi; Harris, Michelle; Coggon, Jude; Teagle, Damon A H; Kelemen, Peter B; The Oman Drilling Project Phase 1 Science Party (2021): Lithology, major, volatile and trace element composition of Hole BT1B samples (Semail ophiolite; ICDP Oman drilling project). PANGAEA, https://doi.org/10.1594/PANGAEA.93749