[1] An in-depth Sr-Nd-Pb-He-Os isotope and trace element study of the EMII-defining Samoan hot spot lavas leads to a new working hypothesis for the origin of this high Sr/Sr mantle end-member. Systematics of the Samoan fingerprint include (1) increasing Pb/Pb with time from 18.6 at the older, western volcanoes to 19.4 at the present-day hot spot center, Vailulu’u Seamount, (2) en-echelon arrays...

Olivine from the deep mantle-derived rocks, such as ultramafic lamprophyres, carries important information about composition of mantle source, processes metasomatism, origin specific silicate-carbonate melts, well and mechanisms crystallization these rocks. Textures compositions olivine carbonate-rich lamprophyres (aillikites) Terina complex, along with their mineral melt inclusions, exposed th...

Mid-ocean ridge basalts (MORB) reveal large mantle compositional heterogeneity, whose origin remains debated. Here we present a systematic study of molybdenum isotopes on well-characterized MORB glass samples from the East Pacific Rise (EPR) and near-EPR seamounts. Our analyses show significant Mo isotope variations with δ98/95Mo (relative to NIST SRM3134) ranging −0.23‰ −0.06‰. We argue that t...

The final closure time of the Paleo-Asian Ocean and Permo-Carboniferous tectonic settings in northern Alxa are very important but controversial issues. geochronology petrogenesis mafic igneous rocks superior clarifying regional settings. Here, we report on zircon U-Pb-Hf isotopes, biotite 40Ar/39Ar whole-rock geochemical data hornblende gabbro from Baogeqi pluton Alxa. LA-ICP MS U-Pb analysis g...

the oligocene-miocene granitic rocks of deh siahan, part of central iranian volcanic belt, are intruded into eocene volcano-sedimentary complex where their contact is marked by albite-epidote hornblende hornfels facies and granitic apophyses. the granitic rocks show enhanced lil element abundances and low hfs/lil ratios. geochemical data, various trace element discriminant diagrams, enhanced y/...

Geochemically diverse basalts occur in an ~160-km-wide transect that stretches across the Quaternary southern Washington Cascades (SWC) volcanic arc. Two fundamental groups of SWC basalts can be identified on the basis of major and trace element chemistry. On primitive mantle-normalized “spidergrams”, Group I lavas resemble within-plate basalts, whereas Group II lavas exhibit chemical character...