This study investigates petrology and major, minor, and rare earth elements ‎geochemistry of ‎East Iranian Eocene–Oligocene volcanic rocks in Sistan suture ‎zone, to examine their ‎petrogenesis and magma evolution. The volcanic rocks include andesite, trachy-andesite, dacite ‎and rhyolite. ‎These calc-alkaline rocks of high-K series are enriched in Large ‎Ion Lithophile ‎Elements of Rb and Ba a...

Monte Amiata is a recently extinct volcano that produced trachydacites and a few small olivine latite flows. The Amiata suite showed crustal strontium, neodymium, and lead isotopic signatures. Sr/Sr ratio values ranged from 0.712447 to 0.713068 and Nd/Nd ratios ranged from 0.512094 to 0.512203. Pb/Pb values ranged from 15.6694 to 16.2330 and Pb/Pb ratios ranged from 18.7125 to 19.0882. The oliv...

High-spatial-resolution (230Th)/(238U) disequilibrium dating reveals rapid zircon crystallization prior to the 12,900 yr B.P. Laacher See (Germany) phonolite eruption. Zircons from Lower Laacher See tephra (LLST) and syenitic subvolcanic nodules share REE and low U/Th characteristics and define an isochron age of 17.1 1.3 ka (1 ). Zircons also show higher initial (Th)/(Th)0 and oxygen isotopic ...

Marie and intermediate granulite xenoliths, collected from Cenozoic alkali basalts, provide samples of the lower crust in western Saudi Arabia. The xenoliths are metaigneous two-pyroxene and garnet granulites. Mineral and whole rock compositions are inconsistent with origin from Red Sea rift-reIated basalts, and are compatible with origin from island arc calc-alkatine and low-potassium tholeiit...

Magmatic stoping is discussed to be a main mechanism of magma emplacement. As a consequence of stoping, abundant country-rock fragments should occur within, and at the bottom of, magma reservoirs as "xenolith graveyards", or become assimilated. However, the common absence of sufficient amounts of both xenoliths and crustal contamination have led to intense controversy about the efficiency of st...

Assimilation of crustal rocks by mafic magmas is considered important for the formation of sulfide ores. Radiogenic isotope systems may allow one to quantify the amount of contamination and to distinguish between possible contaminants. We have studied Sm-Nd, Rb-Sr, and U-Pb isotope systems in two mafic intrusions of the Nain Plutonic Suite: the 1333 Ma Voisey’s Bay intrusion that hosts the majo...

The initial isotopic compositions of Nd and Sr in basalts from the Central Siberian Plateau and other major continental flood basalts are reported. The continental flood basalts appear to be the product of partial melting of mantle sources that consist of relatively primitive undifferentiated material and are clearly distinct from midocean ridge basalts, which sample mantle reservoirs that have...