GRAVITY DIFFERENTIATION OF MASSIVE ORES OF URAL PYRITIC SULFIDE DEPOSITS

Abstract

Vertical zoning in massive pyritic copper-zinc sulfide occurrences in the Urals, as expressed in the replacement from the bottom up of pyrite (sulfur) ore by chalcopyrite-pyrite (copper), sphalerite-chalcopyrite-pyrite (copper-zinc) and sphalerite-pyrite (zinc) varieties, is controlled by many factors. The most important are: 1) the intermittent, pulselike influx of hydrothermal solutions and their natural evolution, during which the latest batches are enriched in copper and zinc; 2) the change in physicochemical environment of ore deposition and the different stability of metals and their compounds in such solutions; 3) the redeposition of copper and zinc from earlier formed ores by subsequent batches of the same solutions. Our work has shown that, besides these factors, the zoning of ore bodies also is influenced to a considerable extent by processes of gravity differentiation of matter as it is precipitated on the floor of a water body.