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Advances in Shock Compression of Mantle Materials and Implications

Ahrens, Thomas J. and Mosenfelder, Jed L. and Asimow, Paul D. (2009) Advances in Shock Compression of Mantle Materials and Implications. In: Shock Compression of Condensed Matter - 2009. AIP Conference Proceedings . No.1195. American Institute of Physics , Melville, NY, pp. 859-862. ISBN 978-0-7354-0732-9.

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Hugoniots of lower mantle mineral compositions are sensitive to the conditions where they cross phase boundaries including both polymorphic phase transitions and partial to complete melting. For SiO_2, the Hugoniot of fused silica passes from stishovite to partial melt (73 GPa, 4600 K) whereas the Hugoniot of crystal quartz passes from CaCi_2 structure to partial melt (116 GPa, 4900 K). For Mg_2SiO_4, the forsterite Hugoniot passes from the periclase +MgSiO_3 (perovskite) assemblage to melt before 152 GPa and 4300 K, whereas the wadsleyite Hugoniot transforms first to periclase +MgSiO_3 (post-perovskite) and then melts at 151 GPa and 4160 K. Shock states achieved from crystal enstatite are molten above 160 GPa. High-pressure Grüneisen parameters for molten states of MgSiO_3 and Mg_2SiO_4 increase markedly with compression, going from 0.5 to 1.6 over the 0 to 135 GPa range. This gives rise to a very large (>2000 K) isentropic rise in temperature with depth in thermal models of a primordial deep magma ocean within the Earth. These magma ocean isentropes lead to models that have crystallization initiating at mid-lower mantle depths. Such models are consistent with the suggestion that the present ultra-low velocity zones, at the base of the lowermost mantle, represent a dynamically stable, partially molten remnant of the primordial magma ocean. The new shock melting data for silicates support a model of the primordial magma ocean that is concordant with the Berkeley-Caltech iron core model [1] for the temperature at the center of the Earth.

Item Type:Book Section
Related URLs:
Asimow, Paul D.0000-0001-6025-8925
Additional Information:© 2010 American Institute of Physics. Issue Date: 28 December 2009.
Subject Keywords:Silicate liquids; Gruneisen parameter; geotherm; magma ocean; early Earth
Series Name:AIP Conference Proceedings
Issue or Number:1195
Classification Code:PACS: 91.60.-x; 02.70.Ns; 82.40.Fp.
Record Number:CaltechAUTHORS:20100618-105854615
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Official Citation:ADVANCES IN SHOCK COMPRESSION OF MANTLE MINERALS AND IMPLICATIONS Thomas J. Ahrens, Paul D. Asimow, and Jed L. Mosenfelder, AIP Conf. Proc. 1195, 859 (2009), DOI:10.1063/1.3295278
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:18734
Deposited By: Tony Diaz
Deposited On:09 Jul 2010 22:57
Last Modified:08 Nov 2021 23:46

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