Migration of Arc Magmatism Above Mantle Wedge Diapirs With Variable Sediment Contribution in the Aegean

Diapirs as the source of the sediment signature in arc lavas

Island arc lavas, erupted above subduction zones, commonly contain a geochemical component derived from partial melting of subducted sediment. It is debated whether this sediment melt signature, with enriched trace element concentrations and isotope ratios, forms at relatively low or high temperatures. Here we compile and analyse the geochemistry of metamorphosed sedimentary rocks that have bee...

Arc-parallel flow within the mantle wedge: Evidence from the accreted Talkeetna arc, south central Alaska

[1] Residual mantle exposures in the accreted Talkeetna arc, Alaska, provide the first rock analog for the arc-parallel flow that is inferred from seismic anisotropy at several modern arcs. The peridotites exposed at the base of the Jurassic Talkeetna arc have a Moho-parallel foliation and indicate dislocation creep of olivine at temperatures of 1000 to >1100 C. Slip occurred chiefly on the (00...

Slab devolatilization and Os and Pb mobility in the mantle wedge of the Kamchatka arc

Os-, Nd-, and Pb-isotope measurements were performed on a suite of eleven Kamchatka peridotite mantle xenoliths in volcanics from the southern (Avachinsky) and central (Sheveluch and Kharchinsky) segments of the Kamchatka peninsula. Peridotites with higher Os content (1.3–5.2 ppb) show a narrow Os / Os range between 0.1182 and 0.1272 while the xenoliths with lower Os content (b1 ppb) show a wid...

Arc magmas sourced from mélange diapirs in subduction zones

At subduction zones, crustal material is recycled back into the mantle. A certain proportion, however, is returned to the overriding plate via magmatism. The magmas show a characteristic range of compositions that have been explained by three-component mixing in their source regions: hydrous fluids derived from subducted altered oceanic crust and components derived from the thin sedimentary ven...

Subduction erosion: Rates, mechanisms, and its role in arc magmatism and the evolution of the continental crust and mantle