HISTORY OF THE RIVER NETWORK DEVELOPMENT, GEOMORPHIC STRUCTURE AND PROSPECTS OF GOLD MINERALIZATION IN THE CENTRAL PART OF SALAIR

Abstract

Geological and geomorphic works were carried out with a geomorphological survey with a detail of 1: 10,000 in the central part of Salair. The middle of the Salair peneplanation planes is widely distributed here – the Late Cretaceous-Early Paleogene, formed at elevations slightly exceeding the denudation basis – the level of the World Ocean at that time, which was 250 m above the modern one. Its current absolute marks are about 400 m, that corresponds to the neotectonic rise of the territory with an amplitude of 150 m. At the beginning of the Quaternary,a vigorous downcutting of hydrographic network occurred with its stabilization and transition to a perstratal regime at elevations 10–15 m below the сurrent encroachment line of stream flows as a result of neotectonic bulging up of the territory and further drawdown in the level of the World Ocean. Massive deposition of aeolian material occurred in the Middle Quaternary. The thickness of the cover loams on watersheds is currently up to 55 m. From valley slopes aeolian loams entered the hydraulic network and overlapped the Early Quaternary alluvium, with which the main gold-bearing alluvial placers of the territory are associated. During reoccurring downcutting, there was an abstraction of watercourse heads of the southwestern slope by watercourses of the northeastern slope of Salair with a displacement of the main watershed in some areas by 5–6 km to the southwest. Emerging buried areas of paleovalleys represent prospective targets in search for placers. The hydrographic network that arose during reoccurrung downcutting does not repeat in detail the Early Quaternary one and ancient alluvium oft en underlays slope deposits with a displacement beyond the bottom of modern valleys to the first tens of meters. Conducting a large-scale geomorphological survey makes it possible to identify areas of ancient valleys with potentially gold-bearing alluvium, which usually remain untested during prospecting and exploration.