Clinopyroxene phenocrysts and microphenocrysts in potassic and sodic Eosen alkaline volcanic rocks from the northern Lahrud (NW Iran) record various stages in the crystallization and evolution history of the alkaline melt as well as its origin. The rock series hosting the clinopyroxene phenocrysts is phonolitic tephrite and tephritic phonolite composition. Theses rocks generally show porphyriti...

in the area sw of arak, intrusives are emplaced into metasediments of early mesozoic age. the intrusive rocks vary in morphology, structure and mineralogy, and exhibit various degrees of alterations; rb-sr geochronological data have been obtained to constrain their timing. there are three different groups of granitic rocks in the area: (a) the astaneh intrusion, consisting of granite, biotite g...

A significant tin deposit has been identified in the northeast part of the Late Proterozoic Arabian Shield. Cassiterite-topaz-quartz greisens are distributed over 16 km2 in flat-topped cupolas of a highly evolved, zinnwaldite-bearing alkali-feldspar granite which composes part of the silsilah ring complex (lat 26"06'N, long 4240'E). The 587 m.y. old alkali-feldspar granite is overlain by a cara...

The accessory mineral assemblage (AMA) of igneous cumulate xenoliths in volcanoclastic deposits and lava flows the Carpathian back-arc basin testifies to composition intrusive complexes sampled by Upper Miocene-Pliocene basalt volcanoes. magmatic reservoir beneath Pinciná maar is composed gabbro, moderately alkalic alkali-calcic syenite, calcic orthopyroxene granite (pincinite). complex wider a...

the eocene volcanic rocks from the southwest of the jandaq (kuh-e-godar-e-siah, central-east iran micro-continent) are andesitic basalt and andesite in composition. these rocks contain xenoliths with granulitic mineralogy. mineral assemblage of these xenoliths is plagioclase + phlogopite + corundum + sillimanite + chlorite + phengite with granublastic, poiklioblastic and foliated textures in th...

Age Determination 105038 Kawano, Y. & Yuhara, M. Chronological and isotope geological study of Cretaceous granitic rocks, upper reach of the Nakagawa river, Fukuoka Prefecture. J. Geol. Soc. Japan, 114, 218-230, 8 figs., 2 tables (in Japanese with English abstract), 2008. Cretaceous granitic rocks, consisting of Itoshima granodiorite and Sawara granite, are occurred at upper reach of the Nakaga...

The 18-km-diameter El’gygytgyn crater is located on the Chukotka peninsula, northeastern Russia. It represents the only currently known impact structure formed in siliceous volcanics, including tuffs. The impact melt rocks and target rocks provide an excellent opportunity to study shock metamorphism of volcanic rocks. The shockinduced changes observed in porphyritic volcanic rocks from El’gygyt...

Abstract Neoproterozoic Abu Ghalaga ilmenite-bearing mafic rocks were subjected to geological, petrographical and geochemical studies integrated with mineral chemistry of ilmenite, pyrite magnetite in order deduce their petrogenesis. intrusions hosting the largest ilmenite reserve Egyptian part Arabian-Nubian Shield. Field observations revealed that impound ore, which occurs as interlayer massi...