The cooling kinetics of plagioclase feldspar as revealed by electron-microprobe mapping

Glass forming ability and crystallisation behaviour of sub-alkaline silicate melts

“…This crystallisation sequence agrees with standard nucleation theory; under dynamic conditions, crystalline phases with lower energetic barriers of formation are more favoured to nucleate (Kirkpatrick 1983;Lasaga 1997;Zhang 2008;Iezzi et al 2008Iezzi et al , 2009Iezzi et al , 2011. (Roskosz et al 2006a(Roskosz et al , 2006bIezzi et al, 2014). The opposite occurs for chemical elements that rapidly diffuse in the melt (network-modifier cations).…”

“…An exhaustive treatment of crystal chemical variations as a function of kinetic conditions will be performed in a further work, together with the chemical evolution of sp and plg, thorough analyses of core-to-rim crystal compositions as shown inMollo et al (2012a) andIezzi et al (2014). The mean oxide compositions of cpx in run-products are reported inTable 5.…”

Clinopyroxene and titanomagnetite cation redistributions at Mt. Etna volcano (Sicily, Italy): Footprints of the final solidification history of lava fountains and lava flows

“…This asymmetric crystal zoning clearly excludes recharge and magma mixing, otherwise clinopyroxene phenocrysts should exhibit axially symmetric core-to-rim chemical variations. A similar feature has been attributed to successive nucleation events in cooled magmas that become progressively more differentiated (Mollo et al, 2012;Iezzi et al, 2014); in this view, after the early formation of primitive minerals, more evolved crystals heterogeneously nucleate onto the pre-existing substrates with ongoing differentiation of the feeding melt. Both textural and compositional analyses of some pahoehoe lavas from pre-historic and historic eruptions at Mt.…”

“…The precision of the microprobe was measured through the analysis of well-characterized synthetic oxides and minerals. Data quality was ensured by analysing these test materials as unknowns according to Iezzi et al (2014). Based on counting statistics, analytical uncertainties relative to their reported concentrations indicate that the accuracy was better than 5%.…”

A tale of two Walker Lane pull-apart basins in the ancestral Cascades arc, central Sierra Nevada, California

“…The more coarse "skeletal" plagioclase textures were not reproduced in those experiments, however, and Tsuchiyama (1985) concluded that such skeletal plagioclase represents mixing under conditions of supercooling, as proposed by Kuo and Kirkpatrick (1982). However, in more recent experiments, Iezzi et al (2014) were able to obtain skeletal plagioclase textures at relatively rapid undercooling with no implicit need for magma mixing, and at the Tequila volcanic field in Mexico, Frey and Lange (2011) were able to link skeletal-type textures to undercooling initiated by magma degassing (rather than magma mixing). Clearly, some of our plagioclase textures are due to magma mixing, but some might also represent near-closed system cooling, or degassing.…”