High-magnesian andesite occurs at Hachimantai, northern Honshu, Japan. Disequilibrium zoning features indicate that the phenocryst minerals were derived from three different magmas. Chemical compositions and zoning profiles are accounted for by two-stage magma mixing: the first mixing occurred between a crystal-free basalt magma and a more differentiated olivine basalt magma; the second stage o...

kuh-e-siah is located in the north of gavkhuni lagoon and east of the varzaneh (se of isfahan) and is a part of urumieh-dokhtar magmatic arc (udma). the volcanic rocks of this area are vesicular basalt and basaltic andesite with late miocene age. the most common textures of these rocks are porphyry, microlitic porphyritic, hyaloporphyric and vesicular. plagioclase, olivine and clinopyroxene are...

The Fronteira Oeste Rift located in the state of Rio Grande do Sul, southern Brazil, covers an area 15,000 km2 and constitutes both a rhombohedral structural province paleohot spring field. These major features can be observed during two-day field trip. A 4x4 vehicle is recommended. weather cold (freezing), humid climate winter hot (35 °C), varying from to dry summer-. Excellent access outcrops...

Sharply defined veins in :stockworks and siliceous breccia matrix contain metallic mineral assembhges and follow a number of subparallel trends within and marginal to a ] p tassium-feldspar porphyritic dacite. The .porphyritic dacite and metal-bearing veins and breccias exhibit both con-. formable and crosscutting relationships with andesite and dacite country rocks of the Hazelton Group. Vein ...

introduction the area reviewed and studied in this paper is located 5 km southeast of sarbisheh city at eastern border of the lut block (jung et al., 1983; karimpour et al., 2011; richards et al., 2012) in eastern iran between 59° 47′ and 59° 53′ e longitude and 32°30′ and 32°34′ n latitude. the magmatic activity in the lut block began in middle jurassic (165-162 ma) and reached its peak in ter...

the protoliths of metamorphosed argillaceous rocks from the garmichay area in the east azerbaijan province of nw iran were clay-rich sediments of reworked nature, originating most likely from an andesite to andesite-basalt source and deposited in an active continental margin tectonic setting. the protoliths of the garmichay metapelites experienced low to moderate chemical weathering. andalusite...