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Publication Detail
Characteristics of HPHT diamond grown at sub-lithosphere conditions (10-20 GPa)
  • Publication Type:
    Journal article
  • Publication Sub Type:
    Article
  • Authors:
    Tomlinson EL, Howell D, Jones AP, Frost DJ
  • Publisher:
    ELSEVIER SCIENCE SA
  • Publication date:
    01/2011
  • Pagination:
    11, 17
  • Journal:
    DIAM RELAT MATER
  • Volume:
    20
  • Issue:
    1
  • Print ISSN:
    0925-9635
  • Language:
    EN
  • Keywords:
    Diamond, Transition zone, Superdeep, Synthesis, HPHT, TRANSITION ZONE, HIGH-PRESSURE, LOWER MANTLE, MINERAL INCLUSIONS, GRAPHITE, SYSTEMS, TEMPERATURE, CARBONATE, METAL, IRON
  • Addresses:
    Tomlinson, EL
    Royal Holloway Univ London
    Dept Geol
    Egham
    TW20 0EX
    Surrey
    England
Abstract
We have conducted high pressure-high temperature (HPHT) diamond synthesis experiments at the conditions of growth of superdeep diamonds (10-20 GPa), equivalent to the transition zone, using MgCO3 carbonate (oxidising) and FeNi (reducing) solvent catalysts. High rates of graphite-diamond transformation were observed in these short duration experiments (20 min). Transformation rates were higher using the metallic catalyst than in the carbonate system. High degrees of carbon supersaturation at conditions significantly above the graphite-diamond stability line, led to a high nucleation density. This resulted in the growth of aggregated masses of diamond outlined by polygonised diamond networks, resembling carbonado. Where individual crystals are visible, grown diamonds are octahedral in the lower pressure experiments (<= 10 GPa in MgCO3 and <= 15 GPa in FeNi) and, cubo-octahedral at higher pressure. All grown diamonds show a high degree of twinning. The diamonds lack planar deformation features such as laminations or slip planes, which are commonly associated with natural superdeep diamonds. (C) 2010 Elsevier B.V. All rights reserved.
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