Magma mixing and exsolution phenomena in peralkaline rhyolites: insights from the Gold Flat Tuff, Nevada

The distribution and compositions of chevkinite-group minerals (CGMs) in the pantelleritic Gold Flat Tuff, Nevada, USA, are used to examine three aspects evolution tuff, which we feel general significance peralkaline magmatism. First, both chevkinite-(Ce) perrierite-(Ce) occur certain facies, although normally these phases almost invariably different igneous lithologies. Their co-occurrence tuff is due mixing intermediate magmas. Second, first recorded occurrence a CGM pantellerite eruptive, with possible implications for crystallization conditions. In particular, low values aSiO 2 may have stabilized ilmenite + chevkinite rather than aenigmatite, unusually high LREE contents (∑La–Sm ≤ 1517 ppm) played role. Third, an unusual lamellar texture revealed by Atomic Force Microscopy be formed rutile-like phase. lamellae exsolution from layer crystal structure. An electron back-scattered diffraction study single showed structural dislocation not apparent optically or imaging. This wider mineralogical studies.