Fig. 8
From: Peridotites with back-arc basin affinity exposed at the southwestern tip of the Mariana forearc
Compositional data for dunite (red) and harzburgite (green). Error bar is the deviation of average values. Green filled circles indicate harzburgite, and red filled circles indicate dunite. a Average Mg# of olivine vs. average Cr# of spinel in the 139°E Ridge peridotites. The region between the two solid lines is the olivine–spinel mantle array (OSMA), where mantle-derived spinel peridotites plot (Arai 1994). b Average Mg# vs. average Cr# for spinel grains in the 139°E Ridge peridotites. c Average TiO2 values vs. average Cr# for spinels in the 139°E Ridge peridotites. d Average TiO2 contents of spinel vs. ΔFMQ values for the 139°E Ridge peridotites. ΔFMQ values were calculated from the major element compositions of olivine and spinel (Ballhaus et al. 1990). ΔFMQ values for abyssal peridotites (Bryndzia and Wood 1990) and forearc peridotites (Parkinson and Arculus 1999) are shown in the vertical lines. e Average TiO2 values vs. YFe values for spinel in the 139°E Ridge harzburgites. The compositional field for the Godzilla Megamullion is shown by green domain (Loocke et al. 2013), the field for the Parece Vela Basin is shown by orange domain (Ohara et al. 2003), the field for the Mariana Trough is shown by blue domain (Ohara et al. 2002a), the field for the “Mariana Trough” outcropped in Mariana Trench is shown by cyan domain (Michibashi et al. 2009), the field for the Yap Trench is shown by magenta domain (Ohara et al. 2002b; Chen et al. 2019), and the field for the Mariana forearc is shown by a dashed line (Ishii et al. 1992; Ohara and Ishii 1998)