Ustyansky Diamondiferous Region in the Central Part of the Russian Platform

Abstract

Ustyansky perspective area is characterized by the combination of all favorable regional and local search prerequisites (morphological, tectonic, geological-stratigraphic, geophysical, morphometric, mineralogical) and search features, which may be due to the introduction of mantle diapir (plume) and may be accompanied by diamondiferous kimberlite magmatism. The content of the diamond indicator minerals with not distant moving: first of all, pyrope, less than picroilmenite, chrome spinel, olivine, and chrome-diopside in the alluvium of the region is 3–5 times higher than in the Zimny Bereg diamond-bearing region, and the share of G10 group diamond paragenesis pyrope is about 10%. Nine diamond crystals were found in panned samples of minimal volume from alluvial and quaternary sediments, of which six crystals (large octahedrons and dodecahedroids up to 3.8 mm in size and weighing up to 52 mg) were found in the predicted kimberlite field “Severnoye”. In terms of morphological features and physical properties, all diamonds of the Ustyansky region occupy a completely isolated position and have virtually no analogues among the diamonds of the known deposits of Arkhangelsk, Finland, the Urals and Timan. This may indicate that the crystals are coming from a new, not yet known kimberlite source (or sources). This potential new root kimberlite source may have an increased diamondiferous capacity, high quality and size of diamonds. The discovery of this new kimberlite source will be the final confirmation of the predicted isolation of the Ustyansky Region as an area of plume activity. Signs of a possible similarity between the Arkhangelsk diamondiferous province and the Yakutian diamondiferous province in terms of kimberlite location patterns and morphological features of diamond crystals confirm the high prospects for diamondiferous activities in the central regions of European Russia as a whole, and, above all, in the Ustyansky promising region with the predicted kimberlite field “Severnoye”.