Specific features of the crust of weathering on dolerites of basic diamondiferous regions of the Siberian platform

Results of complex investigation of the weathering crust on dolerites of basic diamondiferous regions of the Siberian platform (Malo-Botuobinsky, Daldyn-Alakit, and Markoka) which preserved from erosion only in depressions of trappean plateau or in tectonically lowered blocks are given. Alteration of physical-mechanical properties, petrochemical, geochemical and mineralogical specific features on various levels of the weathering crust of northern and southern parts of the region is characterized. On the first stages of hypergene transformation of initially monolithic dolerites there is fissuring development in them, breaking native rocks into individual, relatively large macro- and meso-blocks, which promotes redistribution of some chemical elements. In the result, in indicated meso-blocks, depending on their composition, sufficiently large new formations develop in the form of various pseudo-globular and greatly foliated rosette-like shapes, referred to individual differences of montmorillonite or paragenetic association of vermiculite and Mg-Fe 3+ -montmorillonite, accordingly. The order of alteration of chemical and mineralogical dolerite composition of basic diamondiferous regions of the Siberian platform during weathering indicate that the last ones refer to alkaline type.