Melt retention and segregation beneath mid-ocean ridges

  title={Melt retention and segregation beneath mid-ocean ridges},
  author={Ulrich H. Faul},
  • U. Faul
  • Published 19 April 2001
  • Geology
  • Nature
Geochemical models of melting at mid-ocean ridges—particularly those based on trace elements and uranium-decay-series isotopes—predict that melt segregates from the matrix at very low porosities, of order 0.1%. Some of these models also require that the melt ascends rapidly. But these predictions appear to conflict with seismic data obtained by the mantle electromagnetic and tomography (MELT) experiment. These data reveal, beneath the East Pacific Rise (at 17 °S), a region of low velocities… 

Seismic evidence for partial melt below tectonic plates.

Partial melt occurring within the seismic low-velocity zone is reported on the basis of the interpretation of global three-dimensional shear attenuation and velocity models, suggesting that by reducing viscosity melt facilitates plate motion and large-scale crystal alignment in the asthenosphere.

Permeability of asthenospheric mantle and melt extraction rates at mid-ocean ridges

Application of the measurements in a model of porous-media channelling instabilities yields melt transport times of ∼1–2.5 kyr across the entire asthenosphere, which is sufficient to preserve the observed 230Th excess of mid-ocean-ridge basalts and the mantle signatures of even shorter-lived isotopes such as 226Ra.

Discontinuous Melt Extraction and Weak Refertilization of Mantle Peridotites at the Vema Lithospheric Section (Mid-Atlantic Ridge)

Melting processes beneath the Mid-Atlantic Ridge were studied in residual mantle peridotites sampled from a lithospheric section exposed near the Vema Fracture Zone at 11 N along the MidAtlantic

Carbonate-rich melts in the oceanic low-velocity zone and deep mantle

Deep extensions of low seismic velocities in the mantle beneath volcanic centers are commonly attributed to high temperatures and have been used as a possible characteristic of hot plumes originating

Uranium-series Disequilibria in Mid-ocean Ridge Basalts: Observations and Models of Basalt Genesis

Mid-ocean ridges account for more than 75% of the annual magmatic output of planet earth and are a critical piece of the plate tectonic model. Understanding the mantle melting process beneath ridges

Ultralow viscosity of carbonate melts at high pressures.

Knowledge of the occurrence and mobility of carbonate-rich melts in the Earth's mantle is important for understanding the deep carbon cycle and related geochemical and geophysical processes. However,

Microtomography of Partially Molten Rocks: Three-Dimensional Melt Distribution in Mantle Peridotite

Using x-ray synchrotron microtomography, three-dimensional data on melt distribution for mantle peridotite with various melt fractions is obtained and it is shown that the porosity of the partially molten region beneath ocean ridges is controlled by a balance between viscous compaction and melting rate, not by a change in melt topology.

Low seismic velocities below mid‐ocean ridges: Attenuation versus melt retention

The first comprehensive seismic experiment sampling subridge mantle revealed a pronounced low-velocity zone between 40 and 100 km depth below the East Pacific Rise (EPR) that has been attributed to

Trapped Melt in the Josephine Peridotite: Implications for Permeability and Melt Extraction in the Upper Mantle

Tabular dunites in the Josephine peridotite of southwestern Oregon represent conduits for melt extraction from the upper mantle. The amount of melt trapped within these channels during cooling and



A review of melt migration processes in the adiabatically upwelling mantle beneath oceanic spreading ridges

We review physical and chemical constraints on the mechanisms of melt extraction from the mantle beneath mid–ocean ridges. Compositional constraints from MORB and abyssal peridotite are summarized,

Mantle Melting and Basalt Extraction by Equilibrium Porous Flow

The chemical composition of mid-ocean ridge basalt, the most prevalent magma type on the planet, reflects the melt's continuous reequilibration with the surrounding mantle during porous flow. Models

Permeability of partially molten upper mantle rocks from experiments and percolation theory

Experiments with olivine and a basaltic melt were conducted to analyze the melt distribution in partially molten aggregates at low melt fractions. Grain size and melt distribution at the start of an

Role of a Cl-bearing flux in the origin of depleted ocean floor magmas

Plagioclase‐hosted melt inclusions from ocean floor lavas are characterized by great diversity in their minor and trace element compositions. The incompatible element contents of the inclusions range