MORB or subduction zone magmatism: Discussion for the paper by Asaki and Yoshida(1998).

Separation of supercritical slab-fluids to form aqueous fluid and melt components in subduction zone magmatism.

Subduction-zone magmatism is triggered by the addition of H(2)O-rich slab-derived components: aqueous fluid, hydrous partial melts, or supercritical fluids from the subducting slab. Geochemical analyses of island arc basalts suggest two slab-derived signatures of a melt and a fluid. These two liquids unite to a supercritical fluid under pressure and temperature conditions beyond a critical endp...

Compositional Diversity of Late Cenozoic Basalts in a Transect Across the Southern Washington Cascades: Implications for Subduction Zone Magmatism

Subduction zone rheology

Rheological flow laws can be obtained from studies using multi-anvil high-pressure systems with synchrotron-based piezometers and strain metrics. The high flux X-ray source provides minute-scale time resolution with accurate measurement of diffraction patterns and direct sample images. Measurements of length changes with an accuracy of one part in 104 are being developed and will provide a new ...

Earthquake hazards on the cascadia subduction zone.

Large subduction earthquakes on the Cascadia subduction zone pose a potential seismic hazard. Very young oceanic lithosphere (10 million years old) is being subducted beneath North America at a rate of approximately 4 centimeters per year. The Cascadia subduction zone shares many characteristics with subduction zones in southern Chile, southwestern Japan, and Colombia, where comparably young oc...

The chemistry of subduction-zone fluids

Subduction zones generate voluminous magma and mediate global element cycling. Fluids are essential to this activity, yet their behavior is perhaps the most poorly understood aspect of the subduction process. Though many volatile components are subducted, H2O is the most abundant, is preferentially fractionated into the fluid phase, and, among terrestrial volatiles, is by far the most effective...