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Processes of deep terrestrial mantles and coresUltrahigh pressure experiments are currently focused on revealing processes occurring deep inside planets. This is in addition to the traditional emphasis on the constitution of planetary interiors, such as the identification of the high pressure perovskite phase of (Mg,Fe)SiO3 as the predominant mineral inside the Earth, and probably Venus. For example, experiments show that the mechanism of geochemical differentiation, separation of partial melts, differs fundamentally in the lower mantles of Earth and Venus than at near surface conditions. In addition to structural transformations, changes in chemical bonding caused by pressure can also be significant for planetary interiors. Measurements of AC and DC electrical conductivity can be obtained at ultrahigh pressures and temperatures, to greater than 80 GPa and 3000 K simultaneously, using the laser heated diamond cell. Anhydrous lower mantle assemblages (perovskite + or - oxide phases) exhibit an electrical conductivity that depends strongly on Fe content. Contrary to traditional assumptions, temperature affects the conductivity of lower mantle assemblages relatively little. The Earth's deep focus seismicity can be explained by the recycling of water into the mantle.
Document ID
19920001511
Acquisition Source
Legacy CDMS
Document Type
Other
Authors
Jeanloz, Raymond
(California Univ. Berkeley, CA, United States)
Date Acquired
September 6, 2013
Publication Date
June 1, 1991
Publication Information
Publication: NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1990
Subject Category
Lunar And Planetary Exploration
Accession Number
92N10729
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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