Geochemical modeling of dehydration and partial melting of subducting lithosphere: Toward a comprehensive understanding of high‐Mg andesite formation in the Setouchi volcanic belt, SW Japan

Abstract

[1] Possible mechanisms for the production of mantle-derived, high-Mg andesite magmas, including (1) partial melting of mantle wedge peridotite by addition of aqueous fluids from the subducting lithosphere and (2) partial melting of the subducting sediments and altered oceanic crust, and subsequent melt-mantle interaction, were examined by geochemical formulation of dehydration, partial melting and melt-solid reactions. The modeling results demonstrate that both mechanisms can reasonably explain the incompatible trace element characteristics of high-Mg andesites in the Setouchi volcanic belt, SW Japan. However, simple hydrous melting of mantle wedge peridotite cannot account for the Sr-Nd-Pb-Hf isotopic compositions of such andesites. By contrast, the latter mechanism, which is consistent with thermal structures beneath the Setouchi volcanic belt, can well reproduce the isotopic signature of those high-Mg andesites.

Geochronology and geochemistry of the high Mg dioritic dikes in Eastern Tianshan, NW China: Geochemical features, petrogenesis and tectonic implications

“…The geochemistry of the diorite dikes is consistent with them being derived from a depleted mantle source, similar to that proposed for other sanukitoids (Beyth et al, 1994;Heilimo et al, 2010;Martin, 1999;Martin et al, 2009Martin et al, , 2005. The sanukitoid HMA suite is widely considered to be generated through interaction of a mantle peridotite with a silicic melt derived from partial melting of a subducting oceanic slab and/or sediment (e.g., Yogodzinski et al, 1994;Tatsumi, 2001Tatsumi, , 2006Tatsumi and Hanyu, 2003;, consistent with experimental results that show that sanukitoid can be produced by partial melting of harzburgitic or lherzolitic mantle (Tatsumi, 2001;Tatsumi and Ishizaka, 1982).…”

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

“…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.…”

Middle Jurassic MORB-type gabbro, high-Mg diorite, calc-alkaline diorite and granodiorite in the Ando area, central Tibet: Evidence for a slab roll-back of the Bangong-Nujiang Ocean

“…Sanukitoid is characterized by strong LILE and LREE enrichments, low HREE contents, high Cr and Ni contents and high Mg # , relatively high Y (N 10 ppm) and Yb (N0.8 ppm), low Sr/Y (b 40) and (La/Yb) N (b 10) ratios (Kamei et al, 2004;Martin et al, 2005). It is generated by reaction of a silicic melt derived from a subducting oceanic slab with a mantle peridotite (Kelemen et al, 2003;Tatsumi and Hanyu, 2003;Wang et al, 2011). Boninite is characterized by high SiO 2 (N 52 wt.%), MgO (N 8 wt.%), very low TiO 2 (b 0.5 wt.%), depletion of HFSE and REE, and enrichment of LILE (Saunders et al, 1987).…”

“…In addition, the Ando calc-alkaline diorites have higher ε Nd (t) values , 1998). Sanukitoid data of Setouchi volcanic belt are from Tatsumi and Hanyu (2003) and magnesian andesite data of Baja California are from Calmus et al (2003). ( than the high-Mg diorites, further excluding fractional crystallization from the high-Mg diorites magma.…”