Imaging the Deep Seismic Structure Beneath a Mid-Ocean Ridge: The MELT Experiment
نویسنده
چکیده
The Mantle Electromagnetic and Tomography (MELT ) Experiment was designed to distinguish between competing models of magma generation beneath mid-ocean ridges. Seismological observations demonstrate that basaltic melt is present beneath the East Pacific Rise spreading center in a broad region several hundred kilometers across and extending to depths greater than 100 kilometers, not just in a narrow region of high melt concentration beneath the spreading center, as predicted by some models. The structure of the ridge system is strongly asymmetric: mantle densities and seismic velocities are lower and seismic anisotropy is stronger to the west of the rise axis.
منابع مشابه
Imaging the deep seismic structure beneath a mid-ocean ridge: the MELT experiment
The Mantle Electromagnetic and Tomography (MELT) Experiment was designed to distinguish between competing models of magma generation beneath mid-ocean ridges. Seismological observations demonstrate that basaltic melt is present beneath the East Pacific Rise spreading center in a broad region several hundred kilometers across and extending to depths greater than 100 kilometers, not just in a nar...
متن کاملGrain-size dynamics beneath mid-ocean ridges: Implications for permeability and melt extraction
Grain size is an important control on mantle viscosity and permeability, but is difficult or impossible to measure in situ. We construct a two-dimensional, single phase model for the steady state mean grain size beneath a mid-ocean ridge. The mantle rheology is modeled as a composite of diffusion creep, dislocation creep, dislocation accommodated grain boundary sliding, and a plastic stress lim...
متن کاملUpper mantle structure beneath the Azores hotspot from finite-frequency seismic tomography
The Azores archipelago is a classic expression of a hotspot that has interacted with a mid-ocean ridge. A variety of geochemical studies and geophysical observations point to the influence of some sort of mantle plume on the formation of the Azores Plateau and the adjacent Mid-Atlantic Ridge (MAR), but the mantle structure beneath the Azores has not heretofore been imaged tomographically at a s...
متن کاملResults from Prior NSF Support: William Menke. Award Number OCE-11965 Amount $304,958; Period 08/15/98-11/30/00, Title Active Seismic Imaging of Axial Volcano, PI's
Period 08/15/98-11/30/00, Title Active Seismic Imaging of Axial Volcano, PI's William Menke & Maya Tolstoy. The region of Axial Volcano, Juan de Fuca Ridge region provides an excellent opportunity to study the interplay between active "hot spot" and "mid-ocean ridge" magmatic systems. Important questions include how the two magma systems are fed; their magma and heat budgets; the degree of inte...
متن کاملThree-dimensional seismic structure of the Mid-Atlantic Ridge (35!N): Evidence for focused melt supply and lower crustal dike injection
[1] We gathered seismic refraction and wide-angle reflection data from several active source experiments that occurred along the Mid-Atlantic Ridge near 35!N and constructed three-dimensional anisotropic tomographic images of the crust and upper mantle velocity structure and crustal thickness. The tomographic images reveal anomalously thick crust (8–9 km) and a low-velocity ‘‘bull’s-eye’’, from...
متن کامل