The Ontong Java and Manihiki oceanic plateaus are believed to have formed through high-degree melting of a mantle plume head. Boninite-like, low-Ti basement rocks at Manihiki, however, imply a more complex magma genesis compared with Ontong Java basement lavas that can be generated by ∼30% melting of a primitive mantle source. Here we show that the trace element and isotope compositions of low-...

Glossary andesite magma or volcanic rock is characterised by intermediate SiO2 concentration. Andesite magmas have rheological properties that are intermediate between basalt and rhyolite magmas. Silica content in andesites ranges from approximately 52 to 66 weight percent. Common minerals in andesite include plagioclase, amphibole and pyroxene. Andesite is typically erupted at temperatures bet...

The Earth stands out in the solar system as the only planet with plate tectonics. This peculiarity is due not only to strong internal heating but also a lithosphere rheology characterized by brittle failure and localization, as a comparison with Venus clearly show. Localization in the ductile regime are manifested on Earth by ductile shear zones, which have proven difficult to explain theoretic...

We calculate physical properties of rocks in subduction zones using a compilation of mineral physical property measurements, a new set of phase diagrams and subduction-zone thermal models, and apply our results to Cascadia. Observed P-wave speeds of the Juan de Fuca plate west of the Cascadia trench are best matched by a greenschist-facies upper crust and metastable, partially hydrated lower cr...

Analysis of spatial, temporal, geological and geochemical patterns of ophiolites in the Indonesian and New Guinea region indicates a strong correlation with marginal basin development and closure. The spatial distribution of ophiolites is mostly linked with marginal basin producing zones of oblique convergence and collision. Strain partitioning in these zones creates a series of ephemeral plate...

[1] We analyze the role of slab pull acting on the Pacific plate during its early Tertiary change in motion. Slab pull forces are estimated by integrating the negative buoyancy of a 700 km long slab along a revised subduction boundary model adopting the Müller et al. (2008) seafloor age reconstructions. Our results indicate that torques predicted from a simple slab pull model match the Pacific ...