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Using melt inclusions to understand magmatic-hydrothermal evolution in epithermal-porphyry copper environment: some examples from mining areas of Peru and Romania
Published in Adam Piestrzyński, Mineral Deposits at the Beginning of the 21st Century, 2001
L. Grancea, M. Cuney, J. L. Leroy
Plagioclase phenocrysts in andesite-diorite porphyry intrusion of Valea Morii contain recrystallised melt inclusions (with glass, vapor bubble and daughter minerals) which were remelted in the laboratory. Before heating, silicate-melt inclusions were microcrystalline masses of plagioclase, K-feldspar, pyroxene, quartz, and titanite, mineral phases identified by SEM. The presence of a fluid phase (brine) and also hydrous silicate phases was evidenced by Raman spectroscopy in some inclusions hosted by feldspar (Fig. 1). Major element analysis (EMPA) for different homogeneized inclusions are variable, according to their position in the zoned host plagioclase. The residual silicate melt trapped in plagioclase has a metaluminous to slightly peraluminous composition and a variable Cl content (up to 3.33*103 ppm) and S values up to 1.2*103 ppm. High concentrations of Cu were also detected (up to 2.4*103 ppm and an exceptionally value of 7.7*103 ppm). Some Cl-rich clusters were observed by SEM in the glass inclusions (after heating).
Influence of host magma alkalinity on trachytic melts formed during incongruent orthopyroxene dissolution in mantle xenoliths
Published in New Zealand Journal of Geology and Geophysics, 2020
Andreas Auer, Marco Brenna, James M. Scott
Melt reaction zones and melt inclusions in mantle xenoliths have attracted much interest because they may be a valuable analogue to primary melt generation within the mantle (Arai and Abe 1995). Many previous studies have focussed on samples from individual volcanos (Tracy 1980; Arai 1994; Shaw and Edgar 1997; Klügel 1998; Shaw et al. 2006) or on laboratory experiments under variable controlled conditions (Shaw et al. 1998; Shaw 1999; Shaw and Dingwell 2008). Our selected suite of samples covers a range of different mantle peridotites found within host magmas (Figure 4) that vary from mildly to moderately alkaline (e.g. Dunedin Volcano) to strongly alkaline hosts rock compositions (e.g. Three Kings volcano).