ГЕОЛОГО-ГЕОМОРФОЛОГИЧЕСКИЕ УСЛОВИЯ ФОРМИРОВАНИЯ И СОХРАННОСТИ РОССЫПЕЙ ЗОЛОТА В БЕЛЬСКОЙ МЕЖГОРНОЙ ДЕПРЕССИИ (ЮЖНЫЙ УРАЛ)

Abstract

An analysis of the geological and geomorphological features of the formation and preservation of gold placers in the Pribelsky placer zone located in the central part of the Belsky intermountain depression in the Southern Urals revealed the following. Valley of River Belay within Belsky depression, inheriting a zone of the Zyuratkulsky deep break, has complex two-level structure. The upper tier is represented by a wide (up to 5 km) trough-like paleovalley with complexes of polygenic and polychronic Miocene-Pliocene formations, both preserved in deep (up to 20–37 m) erosion-karst depressions and in some places coming to the surface. In Beloretsky and Burzyansky prospective sites of these complexes gold-bearing was revealed. As a result of the Eopleistocene – Early Neopleistocene phase of the neo-tectonic uplift of the mountainous part of the Bashkir Urals and subsequent river incision into the bottom of the paleo-valley to a depth of 30 to 130 m, a complex of sediments of the lower tier of the modern Belay river valley was formed. Due to the incision and reworking of goldbearing formations of the upper tier, the weight contents of gold are also established in the braid deposits of the river Belay. It has been shown that the areas of paleo-valley river Belay with karst troughs-traps of placer gold associated with zones of increased fracturing and permeability at the junctions of the submeridional and secant transverse faults. Attention is also drawn to the sites of the inheritance of the paleo-valley by a modern network with a predicted greater concentration of metal in them, even if weakly gold-bearing loose formations.