Setouchi high-Mg andesites revisited: geochemical evidence for melting of subducting sediments

Late Triassic high-Mg andesite/dacite suites from northern Hohxil, North Tibet: Geochronology, geochemical characteristics, petrogenetic processes and tectonic implications

“…5c). The andesite samples exhibit high wt.%), Mg # (64-72), and Cr (272-531 ppm) and Ni (66.7-636 ppm) contents, which are similar to typical Cenozoic high-Mg andesites in arc settings, e.g., "adakitic" and "Piip" high-Mg andesites in the Aleutian islands (Alaska) and the Kamchatka Strait to the west of the Aleutian islands (e.g., Yogodzinski et al, 1994Yogodzinski et al, , 1995Yogodzinski et al, , 2001Yogodzinski and Kelemen, 1998), bajaites in Baja California (Mexico) (Calmus et al, 2003;Saunders et al, 1987), sanukitoids in the Setouchi Volcanic Belt (SW Japan) (Shimoda et al, 1998;Tatsumi, 2001;Tatsumi and Ishizaka, 1981) and boninites of the Bonin Islands (Japan) (e.g., Taylor et al, 1994;Umino, 1986) (Fig. 6a-e).…”

“…MORB data are from Niu and Batiza (1997). The data for sanukitoids in SW Japan are from Shimoda et al (1998), Tatsumi (2001, Tatsumi and Ishizaka (1981), and references therein. The data for Bonin Island boninites are from Taylor et al (1994) Umino (1986), and references therein.…”

“…The compositional disequilibrium characteristics of the augites suggest that the Hohxil high-Mg andesites were likely derived by interaction between melts and mantle (e.g., Rapp et al, 1999;Yogodzinski and Kelemen, 1998). However, the origin of the melts requires further clarification, given that similar melts have been attributed to partial melting of delaminated or subducted continental crust (e.g., Gao et al, 2004;Wang et al, 2006bWang et al, , 2008cXu et al, 2008), subducted basaltic oceanic crust, or sediments (e.g., Kay et al, 1993;Kelemen et al, 2003;Shimoda et al, 1998;Tatsumi, 2001;Tatsumi and Hanyu, 2003;Yogodzinski and Kelemen, 1998;Yogodzinski et al, 1994Yogodzinski et al, , 1995.…”

“…The Hohxil high-Mg andesites are geochemically similar to Cenozoic sanukitoids in the southwestern Japan arc (Figs. 5-7), which are considered to have been generated by the interaction of subducted oceanic sediment-derived melts and mantle peridotites (Shimoda et al, 1998;Tatsumi, 2001;Tatsumi and Hanyu, 2003). Second, the Hohxil high-Mg andesite and dacite suites have PGE compositions similar to those of slab meltmetasomatized pyroxenite veins in Kamchatka arc mantle peridotites, and comparable to those of Kamchatka arc adakites (Kepezhinskas et al, 2002) (Fig.…”

Neoarchean siliceous high-Mg basalt (SHMB) from the Taishan granite–greenstone terrane, Eastern North China Craton: Petrogenesis and tectonic implications

“…This clearly demonstrates that a greater proportion of sedimentary-and/or basaltic-derived slab melts have been involved in their generation Pearce and Peate, 1995;Bédard, 1999). Several studies have established that the enriched nature of most Cenozoic high-Mg rocks, including high-Mg andesites and boninites, can be attributed to a contribution from slab-derived melts (Kay, 1978;Cameron et al, 1983;Pearce et al, 1992;Yogodzinski et al, 1994;Shimoda et al, 1998;Tatsumi, 2001;Bindeman et al, 2005;König et al, 2010). Furthermore, the coeval occurrence of boninites with high-Mg andesite and slab melt-related rocks (e.g., adakites) has been recognized in some present-day arcs (e.g., Tonga, Falloon et al, 2008;IzuBonin-Mariana Fore-arc, Pearce et al, 1992), providing evidence of slab melt-related enrichment.…”