The deep geodynamics of Southeast Russia and the setting of platinum-bearing basite-hyperbasite massifs.

The southeastern part of the North Asia craton was found to contain several circular basite-hyperbasite plutons with associated commercial platinoid placers. An analysis of geodynamic models for the formation of the region and materials of seismic tomography showed that the subduction processes that were active in the Asia-Pacific convergence zone during Mesozoic time generated a stagnant oceanic slab in the transitional mantle zone. The NE and SW boundaries of the slab appear to be coincident with transform faults. The projection of the transform fault that bounds the slab on the north-northeast coincides with the Konder-Feklistov metallogenic belt that was identified previously and its Aldan (Inagli) segment. The high platinoid potential of the circular massifs in the belt is explained by the effects of lower-mantle derivates on ascending upper-mantle plumes. [ABSTRACT FROM AUTHOR]