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Abstract <p>The conditions of phase formation in metallic inclusions in natural diamonds from kimberlites have been analyzed on the basis of experimental results on the growth of diamonds and the phase diagram of the iron‒carbon system at high pressures and temperatures. Metallic inclusions are present in both lithospheric and sublithospheric diamonds associated with both peridotite and eclogite assemblages of mantle minerals. It is argued that the equilibrium phases at the postcrystallization stage of the genesis of natural diamonds are iron carbides and oxides; the presence of native metals in the inclusions indicates that the equilibrium has not been achieved. In addition, the presence of native iron in the inclusions indicates a rapid decrease in pressure and temperature at the postcrystallization stage of the genesis of natural diamonds. The change in <i>PT</i> parameters during transportation of diamonds to the Earth’s surface probably occurred as an explosion process, specifically, an abrupt pressure drop at a high temperature maintaining for some time.</p>

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Metallic Inclusions in Natural Diamonds and Their Evolution in the Postcrystallization Period

  • 期刊论文

  • 发表日期：

    2025年2月1日

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  • V. M. Sonin,
  • A. I. Chepurov,
  • E. I. Zhimulev,
  • A. A. Chepurov,
  • A. M. Logvinova,
  • N. P. Pokhilenko

摘要

Abstract

The conditions of phase formation in metallic inclusions in natural diamonds from kimberlites have been analyzed on the basis of experimental results on the growth of diamonds and the phase diagram of the iron‒carbon system at high pressures and temperatures. Metallic inclusions are present in both lithospheric and sublithospheric diamonds associated with both peridotite and eclogite assemblages of mantle minerals. It is argued that the equilibrium phases at the postcrystallization stage of the genesis of natural diamonds are iron carbides and oxides; the presence of native metals in the inclusions indicates that the equilibrium has not been achieved. In addition, the presence of native iron in the inclusions indicates a rapid decrease in pressure and temperature at the postcrystallization stage of the genesis of natural diamonds. The change in PT parameters during transportation of diamonds to the Earth’s surface probably occurred as an explosion process, specifically, an abrupt pressure drop at a high temperature maintaining for some time.