Report on Diamond Drilling at Bridge Creek and Howley Siding Prospects EL 4737

Abstract

During September - November, 1985, a diamond drilling programme consisting of six holes and comprising 1,205 metres was completed in the Bridge Creek - Howley Siding area. Five holes were drilled at Bridge Creek to test a RRMIP anomaly associated with a major, regional anticlinal structure and to establish the presence of Middle Koolpin Formation in the axis of the fold. The source of the RRMIP anomaly was attributed to strongly pyritic, carbonaceous mudstone in the Upper Koolpin Formation. However, because of the tight character of the fold structure the drill holes failed to intersect the Middle Koolpin Formation, which may be located at prohibitive exploration depths at Bridge Creek. One hole was drilled at Howley Siding to explore another substantial RRMIP anomaly, establish the stratigraphy and test for stratiform gold mineralization within the Middle Koolpin Formation which crops out at surface. Disappointingly low gold values were obtained through the sequence which appears to contain poorly developed banded iron formation lacking a strong suplhide component. Promising mineralization, hosted by Gerowie Tuff, in the transition zone from Gerowie Tuff to Upper Koolpin Formation and localised on the western limb of the fold structure, was intersected in two drill holes, 400 metres apart, at the northern end of the Bridge Creek Prospect. The gold values were related to quartz-sulphide, chalcopyrite and minor galena. The mineralized zone averaged 1.80 g/t Au over 23 metres intersection width including 6 metres averaging 3.61 g/t Au in drill hole BC2. A programme of reverse circulation percussion drilling is recommended to: (i) systematically test gold values associated with quartz stockwork and quartz veins in costeans in the fold nose area; (ii) test for any extension of the gold mineralization zone in the area between drill holes,BC1 and BC2 and along the strike of the western limb generally; (iii) verify and test mineralization associated with the line of shafts between costeans Cl8 and C26 in the fold nose area.