INDICATOR MINERALS OF PRESUMABLY PRECAMBRIAN DIAMONDIFEROUS ROCKS OF THE NORTHEASTERN SIBERIAN PLATFORM

So far, the possibility of existence of Precambrian diamondiferous magmatites has been based mainly on diamonds. The absence of their indicator minerals was explained by increased mechanical wear of diamonds, at which the indicator minerals are completely destroyed by abrasion. However, there is evidence of the presence of pyrope in Lower Cambrian sediments in the northeast of the Siberian Platform, which indicates the Precambrian age of the bedrock springs. In addition, in the Kyutyungde River basin in the area of the Sololian protrusion of Precambrian rocks (southern part of the Olenek Rise), we found an unusual association of pyrope in modern alluvium, which is not found anywhere else. Its main features are: a very small number of pyrops in schlich samples, while diamonds are more abundant than pyrops; the pyrope association contains an anomalously high number of pyrops of the diamond association - up to 40-50%, which is not typical for Phanerozoic kimberlites. Taking into account the geological position (Precambrian rocks protrusion), such pyrops give grounds for a cautious assumption about the presence of diamondiferous rocks of Precambrian age in this area.