Fig. 1: Schematic illustration of Ba isotopes vs Sr isotopes to distinguish the two different end-member models of slab material transport in subduction zones.
From: Mélange dehydration and melting beneath South Sandwich Islands arc
A In the metasomatized mantle wedge model, sediment and AOC (yellow and blue boxes, respectively), which both potentially show fractionated Ba isotope characteristics upon melting and dehydration, respectively (orange and blue horizontal lines extending from boxes), mix with the mantle wedge to form arc magmas. Orange and blue lines represent mixing lines between mantle wedge and sediment melts and between mantle wedge and AOC fluids, respectively. Yellow and blue diamonds represent arc magmas produced by the mixing of sediment melts and AOC fluids, respectively, with DMM. B In the mélange model, sediment, AOC, and the mantle wedge physically mix to form hybrid mélange rocks with a Sr isotope ratio determined by the relative proportions of the components that formed the mélange. The mélange subsequently melts and/or dehydrates to form arc magmas with fractionated Ba isotope signatures. A mixing line between sediment and AOC (purple dashed line) is shown. Purple dotted lines represent mixing lines between the mantle wedge and subducted slab components with different proportions of sediment and AOC. The purple area indicates mélange compositions. Purple diamonds represent arc magmas generated from mélange melting and dehydration. Data sources of the DMM19,23,24,43,91, sediment14,15,19,20,21, and AOC19,22,92,93,94 are all from literature (see text for details).
