Quantitative aspects of the source problem of the material of ore deposits A.I. Krivtsov During any ore genesis, the sources multistage nature of deposition of the of ore material represent the original ore material, which is finally incorporated starting point and must naturally enter, in the deposits. The realization of such along with the integral components, into possibilities in application to actual ore each genetic concept; however, such associations is admissible during the concepts, and the classifications arising unidirectional development of geologic from them, are frequently based only on processes, and the assurance of sequen­ the mechanism of ore deposition and the tial deposition of particular components, nature of the supply medium (in many not disturbed by their dispersal. On the cases, conjeetural). other hand, it is reasonable to assume processes that are contrary to ore deposi­ Smirnov (11) separated the sources tion, so far unsubstantiated by geologic of ore material into three groups: data. 1) juvenile and subcrustal, associated with a basalt magma; 2) assimilational The complexities of the problem noted associated with a granitic magma; and are responsible for the difficulties in 3) extra-magmatic infiltrational, asso­ identifying the ores with their possible ciated with the release of matter by sources of material on the basis of chemically active solutions from various characteristics normally employed: sulfur-, parts of the crust, including its upper­ carbon-, and lead-isotope compositions; most portions. The evolution of the ratios of concentrations of the main metallogenic environments during the rock-forming components; and the metal- Earth's...