Group-Level Summary for Group: M251/4 (ITEM 5998) Group Title: Murrin Murrin base metal/gold exploration A Numbers in Group: 1305, 1306, 1308, 2715, 3746, 5747, 9558, 13733, 14732, 17136, 20362, 20971, 21073 Exploration centred on Murrin Murrin, 55km east of Leonora. Between 1964 and 1983, the exploration emphasis lay towards VMS style copper-zinc mineralization, with short periods aimed at nickel sulphide and asbestos mineralization. From 1983 to 1987, the emphasis has been on gold. Regional geology comprises mafic and ultramafic intrusives (large differentiated sills), mafic to felsic volcanics, conglomerate, greywacke, chert, tuff and fragmental rocks, complexely folded and faulted, and intruded and surrounded by granitoid. The Keith-Kilkenny and Celia lineaments sandwich the area to west and east respectively. Two domains are NNW and NE trending, and are separated by the NE striking Federation Fault. Three small copper mines have been worked in the past - Eulaminna (or Anaconda), Nangeroo and Rio Tinto. Each deposit appears to have some stratigraphic control at a major regional felsic volcanogenic sediment - mafic volcanic contact. VMS exploration was based initially on INPUT airborne EM and magnetic surveys, followed up with grid geophysics, geochemistry and mainly diamond drilling. Much of the EM conductivity, however, proved due to graphitic horizons (shale) and magnetite-rich ultrabasics. Soil geochemistry was subdued and element mobility controls seem to have been poorly understood in early years. After 1970, IP was used more successfully and geological/ geomorphological mapping was used to control geochemical sampling and interpretation. In 1969, copper-nickel gossan was discovered near Central Bore. Drilling however intersected only narrow sulphide mineralization (best 0.1m at 4% Cu + 0.3% Ni). Considerable thicknesses of nickeliferous clay were located in the area; an estimate is reported as a possible 100 million tonnes of between 0.8 and 1.5% Ni. During 1967, five areas were drill-investigated for asbestos. In 1967 it is reported that results indicated a possible economic resource of up to 10 million tonnes. In 1975, however, comments indicate that the deposits were far from economic in terms of both quantity and quality. From 1970, most of the base metal exploration resolved itself around the former workings and stratigraphic extensions, with most success in the Minara (Nangeroo Mine) area. At Minara, local geology comprises the east limb of a syncline; mineralization occurs at or near the top of a thick sequence of volcano- ganic sediments, rhyolite and dacite. Drilling indicated several small shoots of massive sulphide but detailed correlation between holes proved not possible. The best result appears to have been 4.4m at 10.2% Cu, 2.9% Zn. Mineralization is pyrite - pyrrhotite - chalcopyrite - sphalerite. At Rio Tinto, gossan assayed up to 5.5% Cu and 7.5% Zn. Drilling, however, failed to intersect significant economic sulphide. Other gossans at Welcome Well, Pearlshell and Mailman were drilled but with either "insignificant" or "disappointing" results. Volumes A5747 - 5749 present a detailed summary of geology and exploration carried out to 1974. Reporting from 1983 to 1987 is only briefly annotated. Exploration during this period was for gold and consisted mainly of sampling areas of former workings and RC drilling in the immediate vicinity of workings. Best RC results reported were 6m at 19.1ppm Au and 3m at 15.4ppm Au, both at Murrin. Drilling at Rio Tinto intersected a broad zone of anomalous weathered sulphides but all grades were subeconomic, <0.5ppm Au. Exploration was ongoing from 1987. Prospects: Crayfish Creek, Minara, Nangeroo, Randwick Hill, Rio Tinto, Murrin Murrin Assays: Cu, Ni, Zn