A great variety of volatile-rich material is fed into subduction zones, including all sorts of marine sediment, altered oceanic crust and some serpentinized mantle lithosphere1. Subduction delivers these materials to depth, but their subsequent history depends on how pressure and temperature increase together. In the cool shallow subduction zone, !uids are liberated at subsolidus temperatures, ...

Abstract Orthophragmines are a group of discoidal, lenticular or stellate ‘orbitoidal’ larger benthic foraminifera that thrived in shallow-marine environments low-to-middle latitudes during the late Paleocene and Eocene. They consist two phylogenetically independent families with similar morphology, such as Discocyclinidae (with Tethyan genera— Discocyclina Nemkovella ) Orbitoclypeidae three Or...

A conceptual shift is overdue in geodynamics. Popular models that present plate tectonics as being driven by bottom-heated whole-mantle convection, with or without plumes, are based on obsolete assumptions, are contradicted by much evidence, and fail to account for observed plate interactions. Subduction-hinge rollback is the key to viable mechanisms. The Pacifi c spreads rapidly yet shrinks by...

A viscous flow model of a subduction zone is used to calculate the near-trench deformation and topography of the overriding plate in response to tectonic and buoyancy forces. The tectonic force, which is associated with global plate motion, arises from subduction of a cold oceanic lithosphere that shears the overriding lithosphere along the contact between the two plates. The buoyancy force ari...

Carbon fluxes in subduction zones can be better constrained by including new estimates of carbon concentration in subducting mantle peridotites, consideration of carbonate solubility in aqueous fluid along subduction geotherms, and diapirism of carbon-bearing metasediments. Whereas previous studies concluded that about half the subducting carbon is returned to the convecting mantle, we find tha...

Although plate tectonics is well established, how a new subduction zone initiates remains controversial. Based on plate reconstruction and recent ocean drilling within the Izu-Bonin-Mariana, we advance a new geodynamic model of subduction initiation (SI). We argue that the close juxtaposition of the nascent plate boundary with relic oceanic arcs is a key factor localizing initiation of this new...

While modelling studies suggest that mesoscale eddies strengthen the subduction of mode waters, this eddy effect has never been observed in the field. Here we report results from a field campaign from March 2014 that captured the eddy effects on mode-water subduction south of the Kuroshio Extension east of Japan. The experiment deployed 17 Argo floats in an anticyclonic eddy (AC) with enhanced ...

[1] We present three‐dimensional laboratory modeling of the evolution of finite strain and compare these to shear wave splitting observations in the Northwest U.S. under the High Lava Plains (HLP). We show that relationships between mantle flow and anisotropy are complicated in subduction zones and factors such as initial orientation of the olivine fast‐axis, style of subduction, and time evolv...