TY - JOUR A1 - Benard, Antoine A1 - Klimm, Kevin A1 - Woodland, Alan B. A1 - Arculus, Richard J. A1 - Wilke, Max A1 - Botcharnikov, Roman E. A1 - Shimizu, Nobumichi A1 - Nebel, Oliver A1 - Rivard, Camille A1 - Ionov, Dmitri A. T1 - Oxidising agents in sub-arc mantle melts link slab devolatilisation and arc magmas JF - Nature Communications N2 - Subduction zone magmas are more oxidised on eruption than those at mid-ocean ridges. This is attributed either to oxidising components, derived from subducted lithosphere (slab) and added to the mantle wedge, or to oxidation processes occurring during magma ascent via differentiation. Here we provide direct evidence for contributions of oxidising slab agents to melts trapped in the sub-arc mantle. Measurements of sulfur (S) valence state in sub-arc mantle peridotites identify sulfate, both as crystalline anhydrite (CaSO4) and dissolved SO42- in spinel-hosted glass (formerly melt) inclusions. Copper-rich sulfide precipitates in the inclusions and increased Fe3+/Sigma Fe in spinel record a S6+-Fe2+ redox coupling during melt percolation through the sub-arc mantle. Sulfate-rich glass inclusions exhibit high U/Th, Pb/Ce, Sr/Nd and delta S-34 (+ 7 to + 11%), indicating the involvement of dehydration products of serpentinised slab rocks in their parental melt sources. These observations provide a link between liberated slab components and oxidised arc magmas. Y1 - 2018 U6 - https://doi.org/10.1038/s41467-018-05804-2 SN - 2041-1723 VL - 9 PB - Nature Publ. Group CY - London ER - TY - GEN A1 - Bénard, Antoine A1 - Klimm, Kevin A1 - Woodland, Alan B. A1 - Arculus, Richard J. A1 - Wilke, Max A1 - Botcharnikov, Roman E. A1 - Shimizu, Nobumichi A1 - Nebel, Oliver A1 - Rivard, Camille A1 - Ionov, Dmitri A. T1 - Oxidising agents in sub-arc mantle melts link slab devolatilisation and arc magmas T2 - Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe N2 - Subduction zone magmas are more oxidised on eruption than those at mid-ocean ridges. This is attributed either to oxidising components, derived from subducted lithosphere (slab) and added to the mantle wedge, or to oxidation processes occurring during magma ascent via differentiation. Here we provide direct evidence for contributions of oxidising slab agents to melts trapped in the sub-arc mantle. Measurements of sulfur (S) valence state in sub-arc mantle peridotites identify sulfate, both as crystalline anhydrite (CaSO4) and dissolved SO42− in spinel-hosted glass (formerly melt) inclusions. Copper-rich sulfide precipitates in the inclusions and increased Fe3+/∑Fe in spinel record a S6+–Fe2+ redox coupling during melt percolation through the sub-arc mantle. Sulfate-rich glass inclusions exhibit high U/Th, Pb/Ce, Sr/Nd and δ34S (+ 7 to + 11‰), indicating the involvement of dehydration products of serpentinised slab rocks in their parental melt sources. These observations provide a link between liberated slab components and oxidised arc magmas. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 717 KW - Andesitic Avacha volcano KW - oxidation-state KW - oxygen fugacity KW - subduction zones KW - peridotite xenoliths KW - sulfur speciation KW - redox state KW - island-arc KW - dissolution mechanism KW - basaltic systems Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-426184 SN - 1866-8372 IS - 717 ER - TY - JOUR A1 - Ishizuka, Osamu A1 - Hickey-Vargas, Rosemary A1 - Arculus, Richard J. A1 - Yogodzinski, Gene M. A1 - Savov, Ivan P. A1 - Kusano, Yuki A1 - McCarthy, Anders A1 - Brandl, Philipp A. A1 - Sudo, Masafumi T1 - Age of Izu-Bonin-Mariana arc basement JF - Earth & planetary science letters N2 - Documenting the early tectonic and magmatic evolution of the lzu-Bonin-Mariana (IBM) arc system in the Western Pacific is critical for understanding the process and cause of subduction initiation along the current convergent margin between the Pacific and Philippine Sea plates. Forearc igneous sections provide firm evidence for seafloor spreading at the time of subduction initiation (52 Ma) and production of "forearc basalt". Ocean floor drilling (International Ocean Discovery Program Expedition 351) recovered basement-forming, low-Ti tholeiitic basalt crust formed shortly after subduction initiation but distal from the convergent margin (nominally reararc) of the future IBM arc (Amami Sankaku Basin: ASB). Radiometric dating of this basement gives an age range (49.3-46.8 Ma with a weighted average of 48.7 Ma) that overlaps that of basalt in the present-day IBM forearc, but up to 3.3 m.y. younger than the onset of forearc basalt activity. Similarity in age range and geochemical character between the reararc and forearc basalts implies that the ocean crust newly formed by seafloor spreading during subduction initiation extends from fore-to reararc of the present-day IBM arc. Given the age difference between the oldest forearc basalt and the ASB crust, asymmetric spreading caused by ridge migration might have taken place. This scenario for the formation of the ASB implies that the Mesozoic remnant arc terrane of the Daito Ridges comprised the overriding plate at subduction initiation. The juxtaposition of a relatively buoyant remnant arc terrane adjacent to an oceanic plate was more favourable for subduction initiation than would have been the case if both downgoing and overriding plates had been oceanic. (C) 2017 The Authors. Published by Elsevier B.V. KW - subduction initiation KW - Izu-Bonin-Mariana arc KW - arc basement KW - Ar-40/Ar-39 age Y1 - 2017 U6 - https://doi.org/10.1016/j.epsl.2017.10.023 SN - 0012-821X SN - 1385-013X VL - 481 SP - 80 EP - 90 PB - Elsevier CY - Amsterdam ER -