Geochemical mapping of the Mariana arc‐basin system: Implications for the nature and distribution of subduction components

摘要: [1] A new ICP-MS database for glasses from the Mariana Trough, together with published and data arc, provides basis geochemical mapping of arc-basin system. The maps presented here are based on graphic representation spatial variations in proxies principal mantle subduction components. focus is three elements high similar partition coefficients but different behavior systems, namely, Ba, Th, Nb. Two coefficients, Ta Yb, used as normalizing factors. Ratio (Ta/Yb, Nb/Ta, Th/Ta, Ba/Ta, Ba/Th) provide simplest petrogenetic insights, zone addition deviations a MORB array more quantitative component represent an attempt to isolate shown indicate presence variably depleted asthenosphere added components: Nb-Th-Ba component, Th-Ba deep-subduction Ba-only shallow-subduction component. entering system enriched relative N-MORB appears be focused at sites within Trough. present mainly north arc (the Northern Seamount province northern Central Island Province), edge two locations Southern Province. It has distinctively Nb/Ta ratio moderate enrichment Th Ba Its composition distribution that it may not part instead originates lithosphere previously above by small-degree, subduction-modified melts. throughout and, minor amounts, parts back-arc basin. central edges Overall, perspective processes accompany evolution basin prerifting lithospheric enrichment, through arc-rifting volcanism spreading.