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  • This report presents the results of geochemical investigations in the Mount Isa district, northwest Queensland. Samples, mainly from cores, represent Group 2 Shales (comprising Kennedy Siltstone and Spear Siltstone), Urquhart Shale, Native Bee Siltstone, greenstones, and local basic igneous rocks. These have been used to study element distributions in mineralized and unmineralized localities. It was found that primary element dispersions are associated with the 1100 Cu orebody, but not with the Ag-Pb-Zn bodies. This, together with the different modes of occurrence of the orebodies, suggests that the mineralization at Mount Isa took place in two separate events. The Ag-Pb-Zn deposits are considered to be syngenetic whereas the Cu deposits appear to be, in part at least, epigenetic. The chemical evidence suggests strongly that much of the Cu in the silica dolomite bodies was derived from the underlying greenstones. In addition, an attempt has been made to differentiate the Urquhart Shale from the other units on the basis of chemical composition. Of the elements analysed, Ca appears to be the most diagnostic and it may be possible to define the upper limit of the Urquhart Shale using this element.

  • Conodonts from the Upper Cambrian Chatsworth Limestone and Gola Beds and the Lower Ordovician (Tremadocian) Ninmaroo Formation were examined in order to determine the sequence of conodont species. Over 5000 specimens from 600 trough-samples representing a total of 10,000 feet of section were identified. Fifty-three species are described, of which 13 are new and 2 have been given open nomenclature. They are referred to 16 genera, of which one, Strigaconus, is new, and two are indeterminate. No Assemblage Zones could be erected for the Upper Cambrian. However, six Assemblage Zones (in ascending order - Cordylodus proavus, Oneotodus bicuspatus-Drepanodus simplex, Cordylodus oklahomensis-C. findstromi, Cordylodus prion-Scolopodus, Cordylodlls rotundatusC. anglllatus, and Chosonodina herfllrthi-AcodllS) are erected in the Tremadocian. Comparison of our zones with previously described conodont sequences from Europe, North America, and Korea shows that they can be used for intercontinental correlation. Local correlation of sections sampled over a distance of 59 miles shows a diachronous rise of the- lithological members of the Ninmaroo Formation to the south. The phylogenetic relationships of Upper Cambrian and Tremadocian conodont species are discussed. Two root-stocks are recognized in the Upper Cambrian - the coelocerodontids, and the westergaardodinids. A development from a coelocerodontid ancestor of Oneotodus nakamllrai Nogami gave rise to the majority of Tremadocian species, which are characterized by diverse cordylodids and scolopodids. The minor westergaardodinid root-stock gave rise to only two species of Chosonodina. Rates of sedimentation (calculated from the thicknesses of the conodont Assemblage Zones) show a general decrease upwards throughout the sequence, and a decrease southwards along the outcrop, from Black Mountain to Mount Datson.

  • Well preserved assemblages of plant microfossils have been recovered from Lower Carboniferous sediments - principally or entirely marine in origin and Visean in age encountered in four boreholes in the landward Bonaparte Gulf Basin of Western Australia and Northern Territory. The sediments are representative of the following lithostratigraphic units: Bonaparte Beds (upper portion) and overlying Tanmurra Formation (intersected by Bonaparte Nos 1 and 2 Wells, central basinal province of Bonaparte Gulf Basin, Western Australia); Milligans Beds (Spirit Hill No. 1 Well; Spirit Hill and Milligans No. 1 Bores, all located in the southeastern platform region of the basin, Northern Territory) and overlying Burvill Beds (basal portion) of Milligans No. 1 only. The 55 species of plant microfossils recognized are distributed among 32 genera of trilete sporae dispersae, including one new genus, Exallospora, which is instituted for the reception of distally annulate cingulate forms having typically verrucate sculptural elevations. Twenty-two species are referable (six tentatively so) to previously established taxa. The palynological flora is dominated by the pan-Australian, Famennian to ?mid-Carboniferous species Granulatisporites frustulentus Balme, Hassell (emended herein), which accounts for 44-83 percent of the spore populations. Certain (inevitably subordinate) spore forms, either the same as or closely similar to species known from northern hemisphere Lower Carboniferous sediments, lend confirmation to the Visean age previously adduced from the contained fauna.

  • This Bulletin describes the sequence of conodont species in the early Ordovician sediments of the Bonaparte Gulf Basin and the Daly River Basin, northwestern Australia (Fig. 1). The assemblage zones erected by Druce, Jones (1971) for the Lower Ordovician (Tremadocian) of western Queensland are recognized in the Bonaparte Gulf Basin. They are used to correlate the Lower Ordovician sediments both within the Bonaparte Gulf Basin, and between it, the Daly River Basin, and western Queensland. Intercontinental correlations are made on the basis conodonts previously described from Asia, North America, and Europe.

  • An airborne magnetic and radiometric survey of the LAVERTON and EDJUDINA 1:250,000 map areas was flown in 1966 to assist the systematic regional geological mapping of the Western Australian Precambrian Shield, and the search for metals. Virtually the entire magnetic pattern is attributed to differences in magnetic properties between rock units at or near ground level. Geological strikes and the boundaries of major rock units have been interpreted by delineating magnetic trends, by subdividing the area into zones of specified magnetic character, and by assessing the geological significance of these zones by reference to mapped geology.

  • Legacy product - no abstract available

  • Legacy product - no abstract available

  • Legacy product - no abstract available