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ORIGIN OF AUTONOMOUS DIAMOND PLACERS

V. S. Shkodzinsky

Diamond and Precious Metal Geology Institute, SB RAS, Yakutsk, Russia

The obtained evidences of the hot accretion of Earth indicates that kimberlites, lamproites and diamonds were formed from residual melts of the bottom peridotite parts in global magmatic ocean generated as a result of the huge impact heat input during accretion. Rhombic-dodecahedron and rounded diamonds, characteristic of autonomous placers with an unknown mother lode, appeared in relatively silicic acid-rich viscous magmas. The low content of carbon dioxide in them led to a small boiling depth, decompression solidification and explosion of solidified parts of rising pyrogeic columns under the influence of the high internal pressure of gas phase preserved by solidification and to the formation of explosive diatremes insignificant in volume. Therefore, explosion products were ejected mainly onto the Earth’s surface and formed diamond tuffs and tuffizites. Their wash out has led to the formation of autonomous diamond placers, for which it is not possible to find kimberlite pipes, the supposed mother lodes of diamonds.

Keywords: placers, diamonds, magmatic ocean, decompression solidification.

DOI 10.20403/2078-0575-2022-4-64-69

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