Zoning of Massive Sulphide Deposits and Their Origin

Abstract

Vertical and lateral zoning of massive sulphide deposits is well known. Vertical zoning is characteristic of volcanic-hosted deposits (e. g. Kuroko), whereas lateral zoning occurs in sediment-volcanic-hosted ore (e. g. Zhairem). A dynamic model of such zoning would belong to the “barrier reaction” type. An oxide-acidic model is herein proposed for the volcanic-hosted and a reduced-carbon model for the sediment-volcanic-hosted deposits. The first model relates to the boundary of the metalliferous solutions/oxidized water system. Oxidized sulphur components in this system range from S02 to S2−. The acidity and ratio of S2−/SO 2−4 are increased and decreased, respectively, from the base to the upper part of the ore section. The result of these variations is the following sequence (from bottom to top): sulphide-silicate metasomatites, pyrite-, copper- and lead- zinc-pyrite massive ores. The form and size of these ore types is caused by the dynamics of the hydrothermal flow and the size of the recycling zone. According to the reduced-carbon model, the ore is deposited from the hydrothermal brine into depressions on the seafloor. Deposition is controlled by the brine/seawater contact, where sulphate-reduction takes place. The laterally concentric emplacement of lead, zinc and pyrite ores is caused by depletion of the sulphidic ion and concentration of the metallic ions in the brine pool.KeywordsMassive SulphideMassive Sulphide DepositLateral ZoningEcon GeolBrine PoolThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.