New genetic type of diamond deposits - geological peculiarities and origin

Kumdykolskoye diamond deposit of the new genetic type was found in 1980 by geologists of the Kokchetav expedition in the Kokchetav crystalline massif of North Kazakhstan.It contains the great amount of diamonds and enormous explored reserves.It's descovery means that it was found the third type of nature diamond deposits because only kimberlitic and impactitic types were known before it.Three groups of geologists have different viewpoints on genesis of new diamond type.Group one advocates the mantle origin of diamonds.A second idea is that the diamonds were formed in the Earth crust under the ultrahigh pressure of regional metamorphism.A third (our) theory, that is based on geological data (structure of the deposit, petrology of the diamond-bearing rocks and composition of rock-forming minerals, also the diamond peculiarities) is that diamonds were cristallized "in situ" under moderate P-T conditions.