The geological materials in Earth's lowermost mantle control the characteristics and interpretation of seismic ultra-low velocity zones at the base of the core-mantle boundary. Partial melting of the bulk lower mantle is often advocated as the cause, but this does not explain the nonubiquitous character of these regional seismic features. We explored the melting properties of mid-oceanic ridge ...

10 Volcanogenic Massive Sulphide (VMS) deposits are commonly enriched in Cu, Zn and 11 Pb and can also be variably enriched in Au, As, Sb, Se and Te. The behaviour of these elements 12 during hydrothermal alteration of the oceanic crust is not well known. Ocean Drilling Program 13 (ODP) Hole 1256D penetrates a complete in-situ section of the upper oceanic crust providing a 14 unique sample suit...

We present new laser ablation ICP-MS trace element concentration data for 28 elements in 97 mid-ocean ridge basalt (MORB) glasses that cover all major spreading centers as well as Tl concentration data for all mineral phases in five lherzolites from the Lherz massif, France. The ratio between the elements thallium (Tl) and cerium (Ce) is nearly constant in MORB, providing evidence that the depl...

Nosrat-Abad ophiolitic extrusive sequence, located in the Sistan Suture Zone, in south eastern Iran. The extrusive sequence, contains pillow lava, sheet flow and related volcanic-clastic breccias which have undergone low-grade metamorphism. This association shows calc alkaline to tholeiitic affinities. Interpretation of the geochemical data and behavior of the elements in different diagrams rev...

Chlorine stable isotope compositions (delta37Cl) of 22 mid-ocean ridge basalts (MORBs) correlate with Cl content. The high-delta37Cl, Cl-rich basalts are highly contaminated by Cl-rich materials (seawater, brines, or altered rocks). The low-delta37Cl, Cl-poor basalts approach the composition of uncontaminated, mantle-derived magmas. Thus, most or all oceanic lavas are contaminated to some exten...

The Spontang Ophiolite complex represents the most complete ophiolite sequence amongst South Ladakh ophiolites and comprises mantle rocks (depleted harzburgites, dunites minor lherzolites) as well crustal (basalt, isotropic gabbros, layered gabbros etc.). In present study, detailed geochemistry (whole rock mineral chemistry) Sr-Nd isotopic analyses of thirty-six ultramafic- mafic samples have b...

We present new Sr-Nd-Hf isotopic data on mid-ocean ridge basalts from two segments (OH-1, OH-3) between the Oceanographer and Hayes fracture zones at Mid-Atlantic Ridge 33–35°N to constrain nature origin of upper mantle heterogeneity beneath Ridge. Together with major trace elements (Niu et al., 2001), illustrate that sources these lavas comprise three components, i.e., a depleted high radiogen...