The presence of oxidation at the crystal rims, and the formation of a reaction halo of orthopyroxene around the phenocrysts suggest that olivine might be a xenocryst
that is not in equilibrium with the melt that carried it to the surface.
One grain (Zl), larger and older than the other dated grains, is interpreted as a xenocryst
and has a [sup.
2012): Anomalous xenocryst
dispersion during tonalite-granodiorite crystal mush hybridization in the mid crust: Mineralogical and geochemical evidence from Variscan appinites (Avila Batholith, Central Iberia).
4A), where the same ignimbrite unit shows variations in xenocryst
contents ranging from 5 to 15%.
Mineral compositions were determined for clinopyroxene, plagioclase, opaque minerals, apatite and the andalusite xenocryst
Samples for biotite inclusion analysis are a megacryst from the San Martino laccolith and a xenocryst
from an Orano dyke; the xenocryst
is presumed to have been captured from the partially molten Monte Capanne pluton that the dyke intruded.
are composed of orthoclase and reach 2-3 cm in size.
Lavas from the northwestern knoll are fresh, slightly ollvine-phyric lavas with abundant vesicles and rare, partially resorbed plagioclase xenocrysts
Unit D is a relatively fresh, mostly dense but locally scoriaceous, porphyritic trachyandesite with ten to fifteen percent large plagioclase xenocrysts
Pellet-rich tuffistic (volcaniclastic) serpentine kimberlite breccia occupies the southern fissure appendage of the pipe which is extremely rich in mantle xenocrysts
, megacrysts and xenoliths.