| Six types of igneous rock occur in a zone of heterogeneity, disequilibrium, and foliation in the northeastern portion of the Northern Fox Range Pluton, Washoe County, Nevada: host granodiorite, mafic dikes, ovoid discrete dioritic enclaves, very large dioritic enclaves (VLEs), aplite/pegmatite dikes, and special cases including schlieren and net veins. Discrete enclaves increase in abundance near VLEs. Both VLEs and discrete enclaves are composite, with fine- and medium-grained subenclaves.; Quenching of hotter mafic globules in cooler, more felsic magma is indicated by enclave shape and disequilibrium features in enclaves: acicular apatite, blade biotite, calcic spike zone in plagioclase phenocrysts, poikilitic quartz and k-feldspar, and sphene-ocellar texture. Plagioclase An content is similar in host and enclaves. Major oxide and trace element composition indicate that melt fractionation and mixing of different magmas created observed features, but does not distinguish between cogenetic and separate sources for mafic and felsic fractions. |
