EL 220 Gondwana Project - Report on Ranger 34, Cannon Hill Area.

Abstract

Ranger 34 lies within a carbonaceous horizon on the central western side of a large north-west trending syncline which contains a suite of Lower Proterozoic metasedimentary rocks. Schist, carbonate, and amphibolite are present, with the Ranger 34 carbonaceous unit towards the top of the sequence. Carpentarian conglomerate and sandstone of the Kombolgie Formation, and ferruginous sandstone of the Lower Cretaceous Mullaman Beds, unconformably overlie the Lower Proterozoic.

Surface expression within the Ranger 34 grid is good. Plane table mapping of outcrops on the southern half of the prospect

outlined a sequence of interlayered quartzite, recrystallized quartzite, and carbonaceous quartzite. Within the carbonaceous quartzite a breccia zone 200 metres long and up to 15 metres wide was defined. Extensive surface sampling revealed average values of 135 ppm uranium and 1527 ppm copper within the brecciated zone. The iron-brecciated carbonaceous quartzite averaged 35 ppm uranium and 560 ppm copper. No secondary copper or uranium mineralisation was noted in the outcrops. A ground radiometric survey using a hand-held Scintrex BOS-IS scintillometer was conducted on a 10 metre x 10 metre grid over the area of outcrop, and this outlined three anomalous areas within the brecciated zone. Results from surface mapping, sampling, and the ground radiometric survey were used to site diamond drill hole DDH R34-S/1. The hole intersected concordant sequence of carbonaceous, carbonate- Iamphibole, amphibole-carbonate, quartz-amphibole, and garnetiferous rocks. Evidence of flow shearing indicate, major disturbance within the sequence during diagenesis and before complete lithification. Significant secondary copper mineralisation within carbonaceous schist was intersected from 11.88 metres to 21.95 metres. This 10.07 metre interval of core assayed 2.5% copper, but uranium values were extremely low. Below the surface of oxidation sulphide mineralisation occurs throughout the sequence. Sulphides present, in order of abundance, are pyrite, pyrrhotite and minor chalcopyrite. Selected geochemical analysis of the richest sulphide zones yielded low values for uranium, copper, lead, zinc, cobalt, nickel, manganese, gold and silver