PLACER DEPOSITS OF DIAMONDS AND THEIR FORMATION CONDITIONS

This article reviews information from published papers and studies by the authors about placer diamond deposits. Original data were obtained in result of field laboratory-analytical work carried out various countries Africa South America. The main types deposits – fluvial, fluvioglacial, eolian, man-made have been considered characterized. attention is given to fluvial continental placers, which are most diverse, well-studied greatest industrial importance. Primary, secondary mixed distinguished according method feeding; short, moderate long transport distance diamond-bearing material movement. It noted that although short placers (deluvial-proluvial beds watercourses) not value, they very informative for searching root sources. important reliably diagnose these lithological-facies mineralogical features during prospecting works. concepts conditions formation landscape geological developed clarified. Alluvial-proluvial-lacustrine proluvial-lacustrine studied Yakutia Brazil characterized detail. Their characteristic feature their productive strata, being re-deposited products crustal weathering, themselves underwent a hypergenic change at place occurrence, significantly masks primary formation. Continental alluvial redeposition as well marine, yield high-quality expensive diamonds, average value can reach $300–400 per carat. Often, such formed due erosion ancient Proterozoic belong category fossils. summarizes genetic morphological form principle diagram distribution sedimentary reservoirs kimberlite minerals. landscape-dynamic zones sedimentation highlighted. A classification scheme containing has developed. Continental, transitional marine environments distinguished, with further detalization peneplain, alluvial-lacustrine accumulative plain, alluvial-deltaic plain shelf sea basins. shown valley internal structure, thickness, granulometric composition content alluvium influenced dynamic phases annual valleys. Visualization mutual relationship different morpho-genetic given.