Volcanic glass is deposited with trace amounts (0.1–0.6 wt.%) of undegassed magmatic water dissolved in the glass. After deposition, meteoric water penetrates into the glass structure mostly as molecular H2O. Due to the lower dD (‰) values of non-tropical meteoric waters and the 30‰ offset between volcanic glass and environmental water during hydration, secondary water imparts lighter hydrogen ...

The central region of the mainland Lewisian gneiss complex of NW Scotland is a granulite-facies migmatite terrane.With the exception of ultramafic and rare calc-silicate rocks, all other lithologies partially melted during Neoarchaean, ultrahigh-temperature (Badcallian) metamorphism. The clearest evidence is preserved within large layered mafic^ultramafic bodies that exhibit macroscopic feature...

The Yamrang Pegmatite in the Ikhabu Field, Eastern Nepal is Nepal’s primary source of aquamarine. This paper reports detailed mineralogy and whole rock granite pegmatite geochemistry, major trace element data for alkali feldspar muscovite order to classify aquamarine-bearing Pegmatite, elucidate beryl-saturation processes evaluate potential geochemical exploration tools beryl-pegmatites. Five i...

dyke swarms emplacement constitutes one of the conspicuous features of the neoproterozoic arabian-nubian shield (ans) (~950-540ma). based on field investigations, petrographic and geochemical characteristics the dyke swarms in nw sinai (egypt) comprise of mafic (dolerite-trachy-basalt-basalt), intermediate (basaltic-andesite trachy-andesite) and felsic (rhyodacite-rhyolite) varieties. geochemic...

the granites south of mashhad are located in the north-east of iran and occur in the suture zone between the binalud and kopeh dagh areas. these s-type granites are peraluminous with an upper triassic age and include intersecting pegmatites. these pegmatites are homogenous and show simple mineralogical combinations which include k-feldspars (microcline and orthoclase), plagioclase, quartz, mica...

The Precambrian Dullstroom Formation of South Africa, which is predominantly composed of basaltic andesites interbedded with subordinate sedimentary and felsic volcanic strata, represents the ®rst phase of an extended period of magmatism that was responsible for the Bushveld Magmatic Province, including the extrusive Rooiberg Group and the intrusive Bushveld Complex. New geochemical and isotopi...