PETROGEOCHEMICAL FACTORS AFFECTING THE DISTRIBUTION OF ORE FIELDS IN RARE-METAL ORE-MAGMATIC SYSTEMS (IN THE SOVIET NORTHEAST)

Abstract

Combined geochemical studies have been carried out in one of the sectors of the Okhotsk-Chukotka volcanogenic belt (OCVB), within a large magmatogenic intrusivedome uplift that was formed in the late Cretaceous, at the intersection of deep faults in the continent-ocean transition zone. The mineralization and endogenic geochemical fields of concentration (GFC) found within the intrusive-dome rare-metal ore-magmatic systems are, in the source of their ore material, paragenetically associated with the silicic magma chamber that produced the rhyolite-granite complex. In their nature, the endogenic GFC are magmatogenic and, like the granitoids of the Peestrinskiy pluton, are specialized for silver, tin and, to a lesser degree, tungsten. The duration and the multistage nature of formation of the magmatogenic GFC in the ore-magmatic system under study predetermined their multiplicity and the poly-chronous character of their development. GFC of the pneumatolytic and the hydrothermal stages can be distinguished. The petrogeochemical factors in the distribution of the ore fields, and the evolutionary-zonal development of the mineralization and of the associated endogenic geochemical fields within the ore-magmatic systems, expand currently existing ideas concerning the theoretical model of a multilevel geochemical field of natural bodies, make a substantial contribution to the problem of prospecting for concealed mineralization, and enable the genetic nature of the anomalies discovered to be appraised on a fundamentally new basis.