Spontaneous small-scale melt segregation in partial melts undergoing deformation
- Creators
-
Stevenson, David J.
Abstract
A partial melt undergoing large scale deformation is shown to be unstable with respect to small scale redistribution of melt, provided the shear viscosity of the matrix depends on melt fraction. In the physically realistic case where melt "softens" the matrix, melt migrates along the direction parallel to the axis of minimum compressive stress and accumulates in "veins" (melt-rich lenses). The maximum growth rate of the instability is of order —⋵_od ln η/df (⋵_o ≡ largest component of the principal strain tensor, η = shear viscosity, f = melt fraction), and plausibly fast enough to invalidate the conventional applications of Darcy's law (e.g., mid-ocean ridges, subduction zones) since melt migrates into veins in preference to being pervasively flushed vertically. The preferred lengthscale of the instability is poorly determined but probably ∼ meters. Veins may eventually form an interconnected drainage network, allowing rapid vertical flushing of melt.
Additional Information
© 1989 American Geophysical Union. Paper number 89GL01416. Manuscript Accepted: 5 Jul 1989. Manuscript Received: 2 Jun 1989. Comments from N. Sleep and an anonymous reviewer were helpful. This work is supported by NSF Earth Sciences grants EAR8618511 and EAR8816268. Contribution number 4764 from the Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125.Attached Files
Published - grl4474.pdf
Files
Name | Size | Download all |
---|---|---|
md5:0f94d7e04737c5d46edb72f68eb3504e
|
287.8 kB | Preview Download |
Additional details
- Eprint ID
- 44910
- Resolver ID
- CaltechAUTHORS:20140414-090819260
- EAR-8618511
- NSF
- EAR-8816268
- NSF
- Created
-
2014-04-14Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences
- Other Numbering System Name
- Caltech Division of Geological and Planetary Sciences
- Other Numbering System Identifier
- 4764