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An Interconnected Network of Core-Forming Melts Produced by Shear DeformationThe formation mechanism of terrestrial planetary is still poorly understood, and has been the subject of numerous experimental studies. Several mechanisms have been proposed by which metal-mainly iron with some nickel-could have been extracted from a silicate mantle to form the core. Most recent models involve gravitational sinking of molten metal or metal sulphide through a partially or fully molten mantle that is often referred to as a'magma ocean. Alternative models invoke percolation of molten metal along an interconnected network (that is, porous flow) through a solid silicate matrix. But experimental studies performed at high pressures have shown that, under hydrostatic conditions, these melts do not form an interconnected network, leading to the widespread assumption that formation of metallic cores requires a magma ocean. In contrast, here we present experiments which demonstrate that shear deformation to large strains can interconnect a significant fraction of initially isolated pockets of metal and metal sulphide melts in a solid matrix of polycrystalline olivine. Therefore, in a dynamic (nonhydrostatic) environment, percolation remains a viable mechanism for the segregation and migration of core-forming melts in a solid silicate mantle.
Document ID
20020011608
Document Type
Reprint (Version printed in journal)
Authors
Bruhn, D. (Minnesota Univ. Minneapolis, MN United States)
Groebner, N. (Minnesota Univ. Minneapolis, MN United States)
Kohlstedt, D. L. (Minnesota Univ. Minneapolis, MN United States)
Date Acquired
August 20, 2013
Publication Date
February 24, 2000
Publication Information
Publication: Nature
Volume: 403
Subject Category
Geophysics
Distribution Limits
Public
Copyright
Other