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...

Abstract The Proterozoic Chotanagpur Granite Gneiss Complex (CGGC) at the northern boundary of Central Indian Tectonic Zone (CITZ) eastern shield preserves relics fossilized oceanic back-arc crust. We describe field, petrographical and geochemical characteristics mafic rocks comprising pillow basalts dolerites from Bathani area fringe CGGC, India. consist plagioclase feldspar, hornblende, opaqu...

The average chemical compositions of the continental crust and the oceanic crust (represented by MORB), normalized to primitive mantle values and plotted as functions of the apparent bulk partition coefficient of each element, form surprisingly simple, complementary concentration patterns. In the continental crust, the maximum concentrations are on the order of 50 to 100 times the primitive-man...

Abstract The origin and evolution of subcontinental lithospheric mantle (SCLM) are important issues Earth’s chemical physical evolution. Here, we report detailed textural analyses on a xenolith suite from Befang (Oku Volcanic Group, Cameroon Line), which represents major tectono-magmatic structure the African plate. samples sourced spinel-facies dominated by lherzolites. Their texture is catacl...

We report new stepped heating He, Ar, CO2 and water data on a petrogenetically diverse suite of lavas from the Manus back-arc basin, where a plume component has previously been identified. The aim of this study is to evaluate the superimposed effects of degassing and contamination in order to identify mantle source characteristics. CO2 abundances and carbon isotopes in both the vesicle ([CO2] u...

The metamorphic sole rocks at the base of mantle peridotites from the Mersin ophiolite consist of amphibolites and metasedimentary lithologies. Mineral parageneses in the metamorphic sole rocks exhibit amphibolite and greenschist facies assemblages. Geothermobarometric studies based on mineral assemblages and chemical compositions of minerals indicate that average metamorphic temperature during...

Abstract Most efforts to characterize the size and composition of mantle that complements continental crust have assumed mid‐ocean ridge basalt (MORB) source is incompatible‐element depleted residue extraction. The use Nd isotopes model this process led conclusion “depleted MORB reservoir” confined upper ∼30% mantle, leaving lower in a more “primitive” state. Here, we Nb/U Ta/U evaluate mass re...

Long-lived heterogeneities in the mantle are indicated by Nd-Sr-Pb isotopic systematics. Explanations for these variations have invoked either distinct layers in the earth that are preferentially tapped by some source regions (such as plumes rising from the base of the mantle) or small-scale heterogeneities which are ubiquitously distributed through the mantle and tapped differentially in vario...

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