Final report, prospecting authorities 2852, 2929, 3068, 3074, 3179, Waterhouse Range

Abstract

Geological mapping concentrated on the Goyder formation in the Western end of the Waterhouse anticline. The Jay Creek Limestone underlies the Goyder Formation, and consists of algal and oolitic limestone and dolomite, siltstone and clay with thin interbeds of calcarious silty sandstone. The unit outcrops in low resistant ridges characteristically covered with spinifex. The Pacoota sandstone of Cambro-Ordovician age, overlies the Goyder Formation. It consists predominently of quartzose with their interbeds of siltstone. In its basal part, the cement is silicious or the matrix is kaolinite. Grain size ranges from fine to very coarse. The contact with the Goyder Formation is gradational and often difficult to determine precisely because of scree cover. The fauna, abundant cross-beds and ripple marks and presence of glauconite in places have lead workers to consider the depositional environment as shallow marine with vigorous conditions. In the Waterhouse Range, bands of pipe rock outcrop in the lower Pacoota sandstone. The Goyder Formation consists of sandstone, siltstone, clay, dolomite and limestone. The sandstones commonly have a high matrix content which may range up to 50% and mostly a dark yell.o colour. Weathering is so intensive at the surface that feldspars are usually not recognisable in hand spec!imens. The high apparent matrix content may be largely due, in many cases, to the weathering of feldspars. Glauconite sandstones occur in the upper part of the formation. The siltstones are grey or green and occasionally purple stained colour. They are commonly micacious and contain up to an estimated 3% lithic fragments and dark minerals. Many are hard and silicified. The clays are soft and have undergone little or no induration. They outcrop recessively and their presence was mostly interpreted at the surface. The limestones and dolomites are silty, sandy and a dark green in colour. Many marked on the geological map as limestones are probably more truely classified as very calcareous silty sandstones. Folding and faulting of the decollement type is common within the Goyder Formation. Folds are generally of low angle and faults with relatively small displacement. The structural features do not extend with the more competent Pacoota sandstone and Jay Creek limestone. A total of 494 surface rock samples were collected in the Waterhouse Range and can be divided into two groups, rock and gossan samples. 406 gossan samples were collected. The eastern half of the Waterhouse Range mostly has a low copper content (less than 100 ppm in many cases and less than 500 ppm in most). Only at two locations on the southern flank does the highest copper content exceed 1000 ppm. In the Western half of the Range, gossan copper content is quite high. Zinc and lead contents of samples from the eastern Waterhouse Range were encouragingly high. On the basis of these results seven costeans were dug in the eastern part of the Range to further determine their significance. In the costeans, copper content is uniformly low, mostly less than 100 ppm. Most half metre channel samples had less than 0.05% lead and many had less than 0.001% lead. The analysis of gossari and costean samples indicate a possible enrichment in lead and zinc in an easterly direction throughout the Waterhouse Range and a corresponding impoverishment of Cu in the same direction. A radiometric survey was made of all ironstone outcrops. The instrument used was a SAPHYMO-SRAT-SPP-2-NP scintillometer. Values ranged from 50 to 300 counts per second.