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Düring subduction, slab fluids released from the subducting oceanic lithosphere, due to compaction and dehydration reactions, migrate within the slab upwards to the slab-mantle wedge interface. However, migration processes of these dehydration fluids are not well understood yet. Hydrophile volatile elements like sulfur are transported by slab fluids from their source lithologies through the slab and become incorporated in the forming fluid pathways due to precipitation and fluid-rock interaction. Consequently, hydrophile volatiles can be used as tracers to determine intra- slab fluid flow processes. In this project, we investigated an eclogite-facies metabasalt from the HP/LT Akeyazi Metamorphic Complex of the South Tianshan Orogen, NW China. The sample consists of a blueschist matrix cut by several omphacite-dominated HP-veins, which formed under prograde to peak metamorphic conditions. Combining mineral Chemical analyses of the blueschist matrix and the different types of veins with in situ 534S measurements of pyrite, as well as isotope analyses of C, O, Sr and Pb in mineral- and vein separates, we determined the sample's metamorphic evolution and reconstructed the related intra-slab fluid flow. Large pyrite grains recording microbially-derived S and barite inclusions in pyrite indicate seafloor alteration under differently tempered hydrothermal conditions, which affected the protolith pillow basalt prior to subduction. This is further supported by dolomite 513C values dose to seawater-carbonate compositions. Mineral Chemical and isotopic compositions reveal a two stage intra-slab fluid flow under prograde to peak metamorphic conditions responsible for the formation of the omphacite-dominated veins. The first HP fluid, showing MORB-like pyrite 534S signatures of -0.75 ± 1,76%o in the vein, originated from dehydrating ocean floor basalts. The second HP fluid composition suggests, instead, an origin from the basalt-sediment transition as documented by negative pyrite 34S values of-10.75 ± 1.47‰. Pathways formed by the first fluid were reused and enlarged by the second fluid, which however also formed new pathways. This sample, which shows only minor influence of retrograde alteration, provides detailed insights into intra-slab fluid flow and fluid-rock-interaction processes at HP/LT metamorphic conditions and allows a better understanding of fluid transfer and sulfur speciation in subduction zones.

© 2017 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY license Background Continuous electronic fetal heart-rate monitoring is widely used during labour, and computerised interpretation could increase its usefulness. We aimed to establish whether the addition of decision-support software to assist in the interpretation of cardiotocographs affected the number of poor neonatal outcomes. Methods In this unmasked randomised controlled trial, we recruited women in labour aged 16 years or older having continuous electronic fetal monitoring, with a singleton or twin pregnancy, and at 35 weeks' gestation or more at 24 maternity units in the UK and Ireland. They were randomly assigned (1:1) to decision support with the INFANT system or no decision support via a computer-generated stratified block randomisation schedule. The primary outcomes were poor neonatal outcome (intrapartum stillbirth or early neonatal death excluding lethal congenital anomalies, or neonatal encephalopathy, admission to the neonatal unit within 24 h for ≥48 h with evidence of feeding difficulties, respiratory illness, or encephalopathy with evidence of compromise at birth), and developmental assessment at age 2 years in a subset of surviving children. Analyses were done by intention to treat. This trial is completed and is registered with the ISRCTN Registry, number 98680152. Findings Between Jan 6, 2010, and Aug 31, 2013, 47 062 women were randomly assigned (23 515 in the decision-support group and 23 547 in the no-decision-support group) and 46 042 were analysed (22 987 in the decision-support group and 23 055 in the no-decision-support group). We noted no difference in the incidence of poor neonatal outcome between the groups—172 (0·7%) babies in the decision-support group compared with 171 (0·7%) babies in the no-decision-support group (adjusted risk ratio 1·01, 95% CI 0·82–1·25). At 2 years, no significant differences were noted in terms of developmental assessment. Interpretation Use of computerised interpretation of cardiotocographs in women who have continuous electronic fetal monitoring in labour does not improve clinical outcomes for mothers or babies. Funding National Institute for Health Research.

Isotope systematics of the redox sensitive and chalcophile element selenium (Se) were investigated on exhumed parts of subducted oceanic lithosphere to provide new constraints on slab dehydration conditions during subduction. The samples c,, show increasing delta(82/76)Se(NIST3149 )with higher abundances of fluid mobile elements, comprising a larger range (-1.89 to +0.48 parts per thousand) than that of mantle (-0.13 +/- 0.12 parts per thousand) and altered ocean crust (-0.35 to -0.07 parts per thousand). Our data point to pronounced, local scale redox variations within the subducting crust, wherein oxidative fluids dissolve sulfides and mobilise oxidised Se species. Subsequently recrystallising sulfides preferentially incorporate isotopically lighter, reduced Se, which shifts evolving fluids and late stage sulfides to higher delta Se-82/76(NIST3149). Redistribution of Se by repeated cydes of sulfide reworking within the subducted crust can be reconciled with episodes of oxidised fluid pulses from underlying slab mantle in modem subduction zones.