RUSSIAN JOURNAL OF EARTH SCIENCES VOL. 7, ES6001, doi:10.2205/2005ES000189, 2005

Nickel Spherules and Diamond Grains as Indicators of an Impact Event

[122]  The detailed examination of layer J (its uppermost, very thin sedimentary unit J6, whose thickness does not exceed 200  m m) has revealed Ni beads and diamond grains (Tables 17, 18). A layer fragment 1 cm 2 in area separated from a stone cube contained tens of diamond grains (ranging from a submicrons to tens of microns) and hundreds of Ni spherules whose sizes also ranged from a submicrons to tens of microns. Diamond grains and Ni beads of the most typical morphology were examined under a microprobe.

[123]  The MPA of Ni beads was conducted on two microprobes (one equipped with WDS and the other with EDS) and have demonstrated that the Ni beads consist of practically pure Ni with a thin outermost film of NiO (Table 17). The surface of all Ni beads is covered with euhedral crystals, which have sizes of 1-2  m m. Such pure Ni in the form of beads, whose surface is lined with crystals has never been found either in magmatic rocks or meteorites, in which Ni always contains significant admixtures.

2005ES000189-fig32
Figure 32
[124]  The examination of Ni beads and diamond crystals from unit J6 have determined the following modes of their joint occurrence: a - diamond crystals included in Ni spherules (Figure 32a); b - Ni beads sticking to a diamond crystal (Figure 32b). This micrograph also displays individual Ni beads with contact surfaces with diamond and Ni aggregates of unusual shape, which resembles pillow lava (upper top quadrant in Figure 32b); c - Ni bead with traces of its contact with diamond (Figure 32c); d - Ni spherules on a large prismatic diamond (or, perhaps, lonsdaleite) crystal (Figure 32d).


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Citation: Grachev, A. F., O. A. Korchagin, H. A. Kollmann, D. M. Pechersky, and V. A. Tsel'movich (2005), A new look at the nature of the transitional layer at the K/T boundary near Gams, Eastern Alps, Austria, and the problem of the mass extinction of the biota, Russ. J. Earth Sci., 7, ES6001, doi:10.2205/2005ES000189.

Copyright 2005 by the Russian Journal of Earth Sciences

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