Important Role of Paleogeomorphological Conditions of Dispersion and Secondary Concentration of Diamond Indicator Minerals in Search for Buried Placers (by the Example of Some Areas in West Yakutia)

Abstract

Specialties of search for buried kimberlite bodies are discussed. Searching in the most commercially developed Daldyn-Alakit and Malo-Botuobiya diamondiferous districts of West Yakutia has shown that there is a need to comprehensively assess the importance of placers transformation with changing palaeogeographical, paleogeomorphological and hydrogeological sedimentation conditions in the post-kimberlite period of geologic history. The topography of the region was formed as a result of geological development of the Tunguska (late Paleozoic), and Vilyui (Mesozoic) basins. In the period of low level of the basins, the buried relief was not merely exposed but incision of new valleys not coincident with the buried river drainage occurred too. Inception of new valleys caused destruction of older ones, which are only locally preserved now. The process of the valleys burial beneath the alluvial deposits is accompanied by significant transformation of some of their elements (slopes, above-floodplain terraces) and by redeposition of slope loose deposits (valleys, channels, terraces, tali). All these factors should be considered for palaeogeomorphological reconstructions of the terrain in search for ancient buried placers and their primary sources.