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Turkish Journal of Earth Sciences

DOI

10.3906/yer-1808-6

Abstract

The concentration of diamond-bearing tagamite from the Popigai impact crater produces large amounts of graphite in addition to impact diamonds (1:100, respectively). The question arises of whether this is residual graphite not converted to diamond at the time of the Popigai impact or is a retrograde form resulting from back-conversion of impact diamond to graphite in a high-temperature tagamite melt. Experiments show that graphite from tagamite is a residual phase. Coexistence of lonsdaleite, cubic diamond, and single-crystal graphite within a limited volume may be due to different orientations of the graphite base plane relative to the impact stress direction. Thus, the diamond-bearing rocks may contain significant amounts of residual graphite, which is consistent with published evidence.

Keywords

Impact crater, impact diamond, graphite, bulk graphitization, surface graphitization

First Page

470

Last Page

477

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