Fig. 6: Discrimination diagrams constraining protolith of the metabasite. | Nature Communications

Fig. 6: Discrimination diagrams constraining protolith of the metabasite.

From: Alpine-style nappes thrust over ancient North China continental margin demonstrate large Archean horizontal plate motions

Fig. 6

a MgO-CaO-FeOtot31 is for the amphibolites, with domain I referring to ortho-amphibolite and domain II to para-amphibolite. Our data is in blue for the picrite-boninite series, red for the tholeiites, plotted with data from other Zanhuang basalts (open circles) from Deng et al.26; b AFM diagram35 showing that the metabasalts plot along the tholeiitic trend; c SiO2 vs. alkalis classification scheme and nomenclature33 for high-Mg volcanic rocks including picrite, basalt, and tholeiite, with the Zanhuang samples plotting in the fields of basalt (for the tholeiites) and near the boundary of the picrite-boninite fields; d SiO2 vs. MgO plot34 with our primitive samples plotting in the picrite-boninite series. Dark gray contour outlines field of Izu-Bonin bonitites. Thick colored lines represent the compositional range of melts modeled by Bénard et al.34 from samples of the hybrid mantle wedges of the Kamchatka and Bismark forearcs, whereas the green, red, and blue lines with arrows represent modeled liquid lines of descent34 from picritic and boninitic parental melts, and the gray lines indicate the melting percent.

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