Home – Home – Jornals – Russian Geology and Geophysics 2018 number Неопубликованное

The Tomtor complex of ultramafic rocks and carbonatites is located in the north of the Sakha Republic (Yakutia). The famous Sc-Y-Nb-REE and Tomtor deposit ores are unique both in terms of their granulometric characteristics - thin-layered, cryptogranular - and in terms of their composition - the average Nb₂O₅ content in the ores of the Buranny site is 4.5%, REE₂O₃ - 10%, Y₂O₃ - 0.75%, Sc₂O₃ - 0.06%. The ore bodies are stratified sheet bodies believed to lie in depressions on the weathering crust. Based on modeling the shape of the roof and base of the ore body, as well as the overlying Permian continental and Jurassic marine sediments of the Buranny site using the QGis and Micromine software packages, the structural and morphological features of the ore bed were identified. The rich ores of the Buranny site lie on a irregular surface. At the base of the ore layer there are two depressions, isolated from each other – Northern and Southern, which are complicated by depressions (pits) of various sizes. There are 10 pits in the Northern Depression and 4 in the Southern Depression. The pits form linear structures that coincide with the faults identified during exploration. Only four pits in the northern part of the site are completely filled with ore substance. The rest are partially and completely filled with coarse-grained coal-bearing sediments of Permian age. In the Southern Depression, the proportion of pit filling with ore is the lowest, and in the deepest pit it is only 25%. It is assumed that the differences are caused by the fact that the pits were formed at different times. Developing the hypothesis that the ores are sediments of a thermal reservoir, the authors suggest that the pits in the base of the ore layer were formed as a result of hydrothermal (phreatic) explosions. Confirmation of the manifestation of fast-flowing high-pressure processes on the Tomtor massif is the discovery, in particular, of tectonic breccias.