Annual Report on Frances Creek EL 4744 period ending 3-12-1987

Abstract

Exploration Licence No. 4744 was explored by CSR Limited during 1987 under the terms of a Joint Venture agreement with Casey Consolidated Holdings. Attention was focussed on assessing the previously outlined geochemical soil anomaly at the Frances Creek Mine Grid by the cutting of an additional 13 costeans which established that geochemical enrichment of gold is present within the remnants of a lateratic weathering profile established on the Zamu Dolerite. Since strong leaching is suspected, final assessment of the exploration potential will rest on an improved structural understanding of the veining and the sampling of the unweathered dolerite below the soil profile. Geological continuity between costeans and correlation between soil geology and subsurface lithologies can only be demonstrated on a fairly general level. It is therefore no surprise that the correlation of gold mineralization is even more tenuous, particularly when consideration is given to the probable mobilization and leaching of gold during pervasive lateritic weathering. Gold enrichment albiet weak and erratic in tenor has been demonstrated to occur in association with quartz, quartz-gossan, and quartz siderite veining within sheared and altered dolerite and sediments over 2.4km of strike. The soil geochemical anomalies are considerably broader than their parent source rocks by virtue of the surface mobility of this material. The detection of the mineralized zones in costean Tll validates the use of soil sampling as an exploration tool although supplementary auger sampling may enhance the method. A study of the analytical results shows that arsenic, copper, lead and zinc are not adequate path finders for gold in this environment at the levels being studied. A significant increase in the tenor of mineralization could only be envisaged if substantial depletion of gold from the weathering profile has occurred. This aspect can only be investigated by drilling. The tendency of the better gold values to occur within veins suggests that mineralization may have been structurally controlled. The substantial development of flat to low angle dipping veins suggests that a regional structural model should be investigated more thoroughly.