The requirements for chemical disequilibrium during magma migration

Spiegelman, Marc; Kenyon, P. M.

doi:10.1016/0012-821x(92)90119-g

Cited by 141 publications

(71 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Some kind of channels have long been assumed in order to explain the geochemical observations [79,22], but a formation mechanism for channels in the viscously deformable parts of the mantle was not known.…”

Section: General Conclusionmentioning

confidence: 99%

“…In order to produce disequilibrium transport, small melt fractions must be efficiently segregated from their source and transported to the crust [28,27,75,26]. Since diffuse porous flow of melt along grain boundaries would lead to extensive chemical reaction and erasure of observed trace element fractionation, some form of focused flow of melt into channels has been proposed to explain extraction of MORB from the mantle [79,22] .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Solid-fluid interactions in porous media : processes that form rocks

Aharonov¹

1996

View full text Add to dashboard Cite

Section: General Conclusionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Solid-fluid interactions in porous media : processes that form rocks

Aharonov¹

1996

View full text Add to dashboard Cite

“…If partial melts ascend to the surface by porous (intergranular) flow processes, the high-pressure garnet signature will be obliterated by diffusive reequilibration at shallower depths in the mantle. Spiegelman and Kenyon [Spiegelman, M. & Kenyon, P. (1992) Earth Planet Sci. Left.…”

Section: Introductionmentioning

confidence: 99%

Equilibration during mantle melting: a fractal tree model.

Hart

1993

Proc. Natl. Acad. Sci. U.S.A.

127

View full text Add to dashboard Cite

Many basalts from oceanic islands, ridges, and arcs show strong trace element evidence for melting at great depths, where garnet is a stable phase in mantle peridotites. If partial melts ascend to the surface by porous (intergranular) flow processes, the high-pressure garnet signature will be obliterated by diffusive reequilibration at shallower depths in the mantle. Spiegelman and Kenyon [Spiegelman, M. & Kenyon, P. (1992) Earth Planet Sci. Left. 109, 611-620] argued that partial melts must therefore be focused into a coarser transport network, for high-speed delivery to the surface. Numerous natural network systems, such as rivers and the human vascular and bronchial systems, have fractal structures that are optimal for minimizing energy expenditure during material transport. I show here that a fractal magma "tree" with these optimal properties provides a network in which magma rapidly loses diffusive chemical "contact" with its host matrix. In this fractal network, magma conduits combine by twos, with the radius and flow velocities scaling as (2)"/3, where n is the generation number. For reasonable values of volume diffusivities, viscosities, and aspect ratios, melts wili experience only limited diffusive reequilibration once they have traveled some hundreds ofmeters from their source. Melts thus represent rather local mantle domains, and there is little problem in delivering melts with deep (<100 km) geochemical signatures to the surface.

show abstract

“…where Pe'=( coh 2)/Ds , K'=Los(1-qb)K]/• f qb), con=(co z)/v, and Ai' (Pe') and A r ' (Pe') are the nondimensional equivalents ofAi and A r. Note that co n is slightly different from co' in Spiegelman and Kenyon [1992] because co n is a variable, rather than a constant.…”

Section: Transport Of Ratios Of Rare Earth Elementsmentioning

confidence: 99%

“…This has been considered previously by Navon and Stolper [1987] for a step-function change in trace element composition, by Kenyon [1990Kenyon [ , 1993 for a cyclical change in trace element concentration as might be seen as heterogeneous mantle is fed into a melting region from below, and by Spiegelman and Kenyon [1992] …”

Section: Introductionmentioning

confidence: 99%

The effect of channel spacing during magma migration on trace element and isotopic ratios

Kenyon

1998

Geophysical Research Letters

View full text Add to dashboard Cite

Abstract. An analytical, mathematical model is discussed for the transport of trace element and isotopic ratios during magma migration, when no major dissolution or precipitation of minerals occurs, but diffusive exchange of atoms between magma and solid is important. This model is then used to elucidate the effect of channel spacing on the transport of trace element and isotopic ratios during the migration of basaltic magma. It is found that, when total reequilibration occurs, as it will in migration through closely spaced channels on grain boundaries, isotopic ratios are transmitted to the surface unchanged but trace element ratios may vary wildly. When channels are far enough apart so that only partial reequilibration occurs, variations in both isotopic and trace element ratios are reduced or eliminated during magma migration. Finally, when channels are sufficiently distant so that negligible reequilibration occurs, both trace element and isotopic ratios are transmitted to the surface unchanged.

show abstract

The requirements for chemical disequilibrium during magma migration

Cited by 141 publications

References 21 publications

Solid-fluid interactions in porous media : processes that form rocks

Solid-fluid interactions in porous media : processes that form rocks

Equilibration during mantle melting: a fractal tree model.

The effect of channel spacing during magma migration on trace element and isotopic ratios

Contact Info

Product

Resources

About