Specific characteristics of terrigenous material in ancient diamond-potential strata

On the example of Mesozoic deposits of one of the main diamondiferous regions of the Siberian Platform, basic suppliers of terrigenous material to ancient placers and their occurrences are characterized. Special attention is paid to characteristics of local sources of allothigenous material transportation to sedimentation basins of this period, the main of which were Middle-Late Triassic weathering crusts of terrigenous-carbonate rocks, formations of trappe origin (dolerites, tuffs, tufogene thick layers), and kimberlites. Comparatively short distance of transportation of weathering products and their accumulation mainly in freshwater continental basins determined a weak hydrothermal influence of environment on allothigenous minerals. The revealed specific features of mineral composition of weathering crusts of various rocks are recommended for application for paleogeographical reconstructions in diamondiferous regions, and to determine source areas of terrigenous material in particular. The stated recommendations were implemented for study the material from local sources of diamondiferous sediments transported to continental (Irelyakh and Ukugut Suites) and coastal (Pliensbachian and Toarcian Stages) deposits of the Malo-Botuobinskiy region, where primary and placer diamond deposits have been successfully mined.