Mafic melt

Petrological and geochemical signatures of mafic enclaves match quite closely those of the Tuscany mafic rocks. However, some of the observed geochemical characteristics may have been modified by interaction with host silicic magmas and could not represent pristine compositions of mafic melts. 

Moderate evolutionary modification of mafic melts during emplacement, with some fractional crystallisation, crustal assimilation (e.g. at Torre Alfina) and unmixing of felsic residual melts at Montecatini Val di Cecina. 

Crustal melting, probably triggered by the emplacement of mafic melts, with generation of peraluminous, highly silicic magmas which were emplaced either as unmodified melts or mixed with different... 

The Tuscany Magmatic Province consists of an association of calc-alkaline to lamproitic mafic to intermediate magmas and silicic intrusive and effusive rocks. Silicic melts have been formed by crustal melting, with an important role of mixing with mantle-derived magmas. Mafic melts are of mantle origin but resemble closely some upper crustal rocks, such as metapelites, in terms of incompatible trace elements and radiogenic isotope... 

In conclusion, although crustal contamination has been an important evolutionary process at most of the Aeolian volcanoes, it seems inadequate to explain the geochemical and isotopic variations observed from calc-alkaline to potassic mafic melts at both local and regional scales. Therefore, many studies concluded that the mafic magmas with different enrichment in potassium reflect primary compositions which were generated in a heterogeneous mantle source (e.g. Ellam et al. 1988 Ellam and Harmon 1990 De Astis et al. 1997, 2000 Francalanci et al. 2004). 

Genesis of Mafic Melts and Composition of Mantle Sources... 

Figure 4 Cl-normalized lithophile element ratios in acapulcoite-lodranite clan (ale), winonaite-IAB-iron silicate inclusion clan (wic) and some unique meteorites showing the effects of melting in the silicate-oxide system. Residual silicate source regions will have low Na/Sc and Sm/Sc, while mafic melts will have the opposite characteristics. Many acapulcoite-lodranite clan and winonaite-IAB-iron silicate inclusion clan meteorites have essentially chondritic lithophile element ratios. Data from sources listed in the text, except for Divnoe (Petaev et al., 1994 Weigel et al., 1997), and Enon (Kallemeyn and Wasson, 1985).

NWA Oil is basaltic in composition, with enrichments in aluminum, calcium, and titanium relative to chondrites, and is ferroan, with an mg of 36. NWA 011 has a cumulate-eucrite-like REE pattern (Figure 6). However, Afanasiev et al. (2000) report that NWA Oil has a negative europium anomaly and samarium content of 13.3 X Cl, more like those expected for a mafic melt composition. Yamaguchi et al. (2002) suggest that the heterogeneous distribution of calcium phosphate is the likely explanation for this discrepancy. This is supported by their hafnium and tantalum analyses, which are at 12.8 X Cl and... 

The role of sulfide-driven (chalcophile) fractionations in lunar magmatism is difficult to constrain, but sulfides presumably play a lesser role on the Moon than on Earth, because the solubility of sulfide in mafic melt increases with decreasing/o (Peach and Mathez, 1993). Compared to lithophile elements of similar volatility, sulfur is exceptionally depleted in terrestrial and martian basalts, but not so depleted in lunar basalts (Figure 6). Medium-Ti mare basalts are clearly unsaturated with sulfide, and although high-Ti mare basalts were originally believed to be sulfide-saturated (Gibson et al., 1977), Danckwerth et al. (1979) found them to be unsaturated, as well. 

The Al-augite series occurs either as discrete xenoliths, or as veins cross-cutting Cr-diopside series peridotite. They are usually interpreted to be high-pressure segregations from hydrous mafic melts. At many locations, the Al-augite series characteristically contains a kaersutitic amphibole and phlogopite (see review by Kempton, 1987). 

Hattori K. H. and Keith J. D. (2002) Contribution of mafic melt to porphyry copper minerahzation evidence from Mount Pinatubo, Phihppines, and Bingham Canyon, Utah, USA. Mineral. Dep. 36, 799—806. 

For metaluminous systems, apatite crystallizes relatively early in the crystallization sequence of felsic magmas, and crystallizes comparatively later in more mafic melts. For example, it was estimated that apatite is a near liquidus phase in the Johnson Granite Porphyry, but began to crystallize after about 1/3 of the Kuna Crest (quartz diorite) magma crystallized (Piccoli and Candela 1994). Ultimately, apatite often first appears as an intercumulus phase in gabbros and related rocks (e g., Boudreau et al. 1986). 

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