Mantle Melting: the achievements, promise, and limits of thermodynamics

1 hour 5 mins, 119.51 MB, MP3 44100 Hz, 251.03 kbits/sec

Share this media item:

Embed this media item:

<iframe width="_width_" height="_height_" src="https://sms.cam.ac.uk/media/2184989/embed" frameborder="0" scrolling="no" allowfullscreen></iframe>

Choose size:

About this item

Available Formats

About this item

Description:	Asimow, P [CALTECH (California Institute of Technology)] Monday 15th February 2016 - 11:30 to 12:30


Created:	2016-02-19 16:54
Collection:	Melt in the Mantle
Publisher:	Isaac Newton Institute
Copyright:	Asimow, P
Language:	eng (English)
Distribution:	World (downloadable)
Explicit content:	No
Aspect Ratio:	16:9
Screencast:	No
Bumper:	UCS Default
Trailer:	UCS Default


Abstract:	This workshop is an opportunity to consider the state of the art in application of thermodynamics to mantle melting. This approach constructs and calibrates Gibbs free energy models for relevant phases, enabling predictions of equilibrium states including phase proportions, compositions, and some physical properties. We will consider the achievements of this approach, its unfulfilled promise, and its theoretical limits. Under achievements, a body of work has applied the MELTS and pMELTS models to upper mantle magmatism in ocean ridge, back-arc, intraplate, and subduction environments. From 0-3 GPa pressure, models of multicomponent minerals and silicate liquid appear good enough to recover most experimental results, to provide an internally-consistent forward model from source peridotite through melting to the observed volume and composition of magmas, to constrain the potential temperature of source regions, to elucidate the role of water, and more. There have been a few forays into integrating this approach with magma dynamics at various scales. Under promise, we expect near-future, improved versions that incorporate carbon species, extend to substantially higher pressure, and account for variable speciation in the melt to achieve higher fidelity. Calibration strategies based on a flexible, evolving, community framework will liberate the enterprise from the slow progress of models based on fixed, internally-consistent datasets. Fully coupled, large-scale dynamical simulations incorporating MELTS thermodynamics are practical and close to implementation. Under limits, we must recall the limitations of the equilibrium assumptions underlying thermodynamics. At some time and length scales these assumptions break down. In a heterogeneous mantle containing species with widely divergent mobility, there must be important roles for kinetics. Progress in incorporating kinetics in major element models has been nearly nil and must be a major focus of our efforts. Related Links http://magmasource.caltech.edu - Links to thermodynamic modeling software mentioned

Abstract:

This workshop is an opportunity to consider the state of the art in application of thermodynamics to mantle melting. This approach constructs and calibrates Gibbs free energy models for relevant phases, enabling predictions of equilibrium states including phase proportions, compositions, and some physical properties. We will consider the achievements of this approach, its unfulfilled promise, and its theoretical limits.

Under achievements, a body of work has applied the MELTS and pMELTS models to upper mantle magmatism in ocean ridge, back-arc, intraplate, and subduction environments. From 0-3 GPa pressure, models of multicomponent minerals and silicate liquid appear good enough to recover most experimental results, to provide an internally-consistent forward model from source peridotite through melting to the observed volume and composition of magmas, to constrain the potential temperature of source regions, to elucidate the role of water, and more. There have been a few forays into integrating this approach with magma dynamics at various scales.

Under promise, we expect near-future, improved versions that incorporate carbon species, extend to substantially higher pressure, and account for variable speciation in the melt to achieve higher fidelity. Calibration strategies based on a flexible, evolving, community framework will liberate the enterprise from the slow progress of models based on fixed, internally-consistent datasets. Fully coupled, large-scale dynamical simulations incorporating MELTS thermodynamics are practical and close to implementation.

Under limits, we must recall the limitations of the equilibrium assumptions underlying thermodynamics. At some time and length scales these assumptions break down. In a heterogeneous mantle containing species with widely divergent mobility, there must be important roles for kinetics. Progress in incorporating kinetics in major element models has been nearly nil and must be a major focus of our efforts.

Related Links

http://magmasource.caltech.edu - Links to thermodynamic modeling software mentioned

Available Formats

Format	Quality	Bitrate	Size
MPEG-4 Video	640x360	1.95 Mbits/sec	950.74 MB	View	Download
WebM	640x360	915.93 kbits/sec	436.05 MB	View	Download
iPod Video	480x270	524.21 kbits/sec	249.57 MB	View	Download
MP3 *	44100 Hz	251.03 kbits/sec	119.51 MB	Listen	Download
Auto	(Allows browser to choose a format it supports)

Streaming Media Service Upload

Mantle Melting: the achievements, promise, and limits of thermodynamics