SMEDG SYDNEY MINERAL EXPLORATION DISCUSSION GROUP

- PREVIOUS MEETING

DATE: Thursday 8 August 1991 at 5.00 pm VENUE: 1st Floor, Rugby Club, Crane Place, Sydney SPEAKER: Tim McConachy - CRA TOPIC: "Hydrothermal Plumed and Volcanogenic Massive Sulphides" Results of sampling of hydrothermal plumes along the East Pacific Rise in water depths of 2500m using the submersible ALVIN indicate that,in the present environment, plume fallout is likely to produce so-called volcanogenic massive sulphide deposits. In order to achieve significant concentrations of sulphide, special conditions are required such as much greater particle mass flux, a slow spreading axis, long-lived hydrothermal convection and discharge into a structural trap with stagnant bottom waters. The talk will show how sampling was undertaken with ALVIN and how analysis and modelling of plume solutions and particles lead to these conclusions.