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Swiss Journal of Geosciences
Fig. 15 | Swiss Journal of Geosciences

Fig. 15

From: The Val Biandino Intrusive Suite (central Southern Alps, N Italy): new geochronological and geochemical data on the Early Permian magmatic activity in the Southalpine Domain

Fig. 15

a The Nb content of the mafic rock types of the VBQD with respect to Zr and Ba (Nb/Ba vs. Nb/Zr diagram of Hooper & Hawkesworth, 1993). Data from this work and literature (De Capitani & Liborio, 1988) show how a sub-continental lithospheric mantle is favourable as a source for the VBQD magmatic rocks. b Th/Yb – Ba/La, c Th/Yb – Cs/Rb and d (Ta/La)PM – (Hf/Sm)PM diagrams (Hartmann & Wedepohl, 1993) that show the sediments and fluids possible contribution to the source of the Biandino gabbrodiorites. e A simple fractionation mechanism of magma derived from a fluid- and/or melt-metasomatized subcontinental lithospheric mantle is supported by the incompatible trace element ratios (Soesoo, 2000) and by the fractional crystallization tendency depicted in the La/Sm vs La diagram for gabbrodiorite of the VBQD. f Relationships between the composition of anatectic melt with respect of the source composition in terms of the Ca/Fe + Mg and Al/Fe + Mg molar ratios (Altherr et al., 2000). The composition of quartz-diorite and granodiorite of the VBQD suggest a contribution derived from partial melting of metapelites-metapsammites (micaschists and paragneisses) and metamorphic mafic rocks (amphibolites) for quartz-diorite

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