Molybdenum and uranium are redox sensitive elements that experience isotope fractionation in the Earth-surface environment. Recent studies have explored transfer of these fractionated signals subduction zones to arc magmas, but less is known about full variation isotopic tracers mantle, particularly domains mantle may feed hot spots. Here, we present Mo U data for lava samples from Pitcairn, Sa...

This dissertation discusses the experimental results designed to constrain the processes of MORB generation. The main focus of this study is to investigate the location and the related processes of the transformation boundary from spinel to garnet peridotite facies at subsolidus conditions, because the presence of garnet in melting residues has significant influence to the conclusion drawn from...

Mantle convection stirs and homogenizes the subducted oceanic lithosphere with the convecting mantle. Convective mixing stretches and thins the subducted oceanic crust from an original thickness of 6 km to a thickness of 2 cm or less. The thinned, subducted oceanic crust can be observed as pyroxenite bands in high-temperature peridotite massifs. On the scale of centimeters, the bands are destro...

Chemical differences between mid-ocean ridge basalts (MORBs) and ocean island basalts (OIBs) provide critical evidence that the Earth's mantle is compositionally heterogeneous. MORBs generally exhibit a relatively low and narrow range of (3)He/(4)He ratios on a global scale, whereas OIBs display larger variability in both time and space. The primordial origin of (3)He in OIBs has motivated hypo...

The oxidation state of iron in mantle-derived melts is commonly used to determine the oxygen fugacity (fO2) magmas and their related sources. accurate precise determination ratio Mid-Oceanic Ridge Basalt (MORB) glasses has been a matter controversy for last three decades. None wet chemical methods literature measure this converge toward consensus value. same difficulties have observed most rece...

A substantial amount of subducted basaltic crusts may exist in the lower mantle. It features distinct chemical composition from peridotitic mantle and plays important roles dynamic evolution Earth's interior. However, mineral phases present crust is still poorly constrained. Here, we determined phase relations normal mid-ocean ridge basalt (MORB) up to 52 GPa at 2000 K by multi-anvil press. Thr...