[1] We report some of the first noble gas data for in situ lower oceanic crust and shallow mantle. From a suite of gabbros and peridotites recovered from the Atlantis Bank oceanic core complex on the Southwest Indian Ridge, we measured He, Ne, Ar, Kr and Xe concentrations as well as He/He and Ar/Ar ratios, there by documenting the noble gas content and signature of oceanic lithosphere. Except f...

The broad belt of intraplate volcanism in the East Atlantic between 25 and 37 N is proposed to have formed by two adjacent hotspot tracks (the Madeira and Canary tracks) that possess systematically different isotopic signatures reflecting different mantle source compositions. To test this model, Hf isotope ratios from volcanic rocks from all individual islands and all major seamounts are presen...

The Jinshajiang–Ailaoshan–Song Ma orogenic belt (JASB), as a vital segment of the eastern Paleo-Tethyan tectonic zone, is one most important zones in which to study evolution. We have undertaken an integrated geochronological, petrological, and geochemical mafic rocks from JASB reveal subduction closure processes Ocean during Permian Triassic. In conjunction with previous magmatic metamorphic r...

Data collated from subalkaline lavas and dikes of Palaeogene ophiolites the SW Pacific in Papua, New Guinea, Caledonia, North Island, Zealand interpreted as having formed first upon subduction initiation, are investigated to determine whether these MORB like, similar other initiation IBM forearc. ophiolite mostly tholeiitic basalt; however, calc-alkaline comprise ~ 25% samples. Major element ab...

Abstract We conducted the geochemical modeling of trace element contents for primary melts olivine-phyric rocks from Kamchatsky Mys. This reveals substantial chemical heterogeneity their source while average composition is close to enriched DMM (E-DMM). The estimation melting degree in range 9.1 ± 3.8% model modal batch 15.4 5.2% accumulated fractional melting, which slightly higher than primit...

Mafic rocks including basalts and gabbros are the main constituents of Birjand ophiolites. They are found in several places and show low grade metamorphism in the field and under the microscope. Chondrite-normalized REE patterns for basalts and gabbros indicate that these rocks are transitional-enriched to depleted mid-oceanic ridge basalts respectively. Otherwise, N-MORB normalized trace eleme...

We report stable Ni isotope compositions (?60/58Ni, relative to SRM986) for mafic lavas with a range of ?0.16‰ +0.20‰ (n = 44), similar that peridotite samples. Ocean island basalts (OIB) have been analysed from Iceland 6), the Azores 3), Galápagos Islands 2), and L??ihi, Hawaii 1). Samples (average ?60/58Ni +0.13 ± 0.16‰, 2s, n 7) display greatest in single OIB location this work, +0.01‰ +0.23...

"Lithosphere" is a mechanical concept implying strength and relative permanence. Unfortunately, the term has also been applied to the surface thermal boundary layer (TBL) and a shallow enriched geochemical reservoir, features having nothing to do with strength. The "strong" lithosphere is about one half the thickness of the TBL. The bottom of the elastic plate, the maximum depths of midplate an...