Abstract The Central Asian Orogenic Belt (CAOB) is one of the largest accretionary orogens on Earth and preserves evidence that more than 50% this orogen represents juvenile crustal growth over an extended period some 750 million years from ca. 1000 Ma to 250 Ma. However, mechanism controversial, as implied by a variety proposed models ranging contributions mantle-derived basaltic underplating ...

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...