Primitive arc magmas are more oxidized and enriched in sulfur-34 (S) compared to mid-ocean ridge basalts. These findings have been linked to the addition of slab-derived volatiles, particularly sulfate, to arc magmas. However, the oxidation state of sulfur in slab fluids and the mechanisms of sulfur transfer in the slab remain inconclusive.
View Article and Find Full Text PDFCalcium-aluminum–rich inclusions (CAIs) in meteorites carry crucial information about the environmental conditions of the nascent Solar System prior to planet formation. Based on models of V–Be co-production by in-situ irradiation, CAIs are considered to have formed within ~0.1 AU from the proto-Sun.
View Article and Find Full Text PDFDiamonds growing in the Earth's mantle often trap inclusions of fluids that are highly saline in composition. These fluids are thought to emerge from deep in subduction zones and may also be involved in the generation of some of the kimberlite magmas. However, the source of these fluids and the mechanism of their transport into the mantle lithosphere are unresolved.
View Article and Find Full Text PDFIn subduction zones, sediments and hydrothermally altered oceanic crust, which together form part of the subducting slab, contribute to the chemical composition of lavas erupted at the surface to form volcanic arcs. Transport of this material from the slab to the overlying mantle wedge is thought to involve discreet melts and fluids that are released from various portions of the slab. We use a meta-analysis of geochemical data from eight globally representative arcs to show that melts and fluids from individual slab components cannot be responsible for the formation of arc lavas.
View Article and Find Full Text PDFPhilos Trans A Math Phys Eng Sci
May 2017
Inner Solar System bodies are depleted in volatile elements relative to chondrite meteorites, yet the source(s) and mechanism(s) of volatile-element depletion and/or enrichment are poorly constrained. The timing, mechanisms and quantities of volatile elements present in the early inner Solar System have vast implications for diverse processes, from planetary differentiation to the emergence of life. We report major, trace and volatile-element contents of a glass bead derived from the D'Orbigny angrite, the hydrogen isotopic composition of this glass bead and that of coexisting olivine and silicophosphates, and the Pb-Pb age of the silicophosphates, 4568 ± 20 Ma.
View Article and Find Full Text PDF