The Canning Basin, which covers some 450,000 km2, is the largest sedimentary basin in Western Australia. The earliest Palaeozoic rocks are widespread marine Ordovician limestone, shale and sandstone up to 3260 m thick which unconformably overlie Precambrian metamorphic and sedimentary rocks. Overlying the Ordovician are Devonian rocks, consisting of evaporites and redbeds (probably Early and Middle Devonian) confined to the centre of the basin, and extensive Late Devonian reef carbonates on the northerly and, perhaps, the southerly margin, together with associated shale and sandstone in the centre of the basin. The Devonian sediments are overlain by Carboniferous, Permian, M e s o z o i c and Cainozoic sediments. During the Late Devonian and Carboniferous, sedimentation was virtually confined to the northern half of the Basin: on the Lennard Shelf, in the Fitzroy Trough, and on the Jurgurra Terrace (Fig. 2). The trough contains up to 6000 m of Carboniferous rocks. The Upper Devonian Lower Carboniferous platform sediments consist of alternating beds of limestone, shale, sandstone, and marl. Generally, they postdate the Devonian reef-complex (Playford & Lowry, 1966) and are poorly exposed; consequently they have received less geological attention than the well-exposed reef carbonates. Previous work has resulted in differing interpretations of the formal stratigraphy; including different nomenclatures for the same rock bodies. The presence of an unconformity has also been questioned. During May - August 1972 a joint Bureau of Mineral Resources (BMR) Western Australian Geological Survey (WAGS) Field Party carried out detailed fieldwork in the vicinity of Fitzroy Crossing, Western Australia. Comprehensive collections of petrographic, palaeontological, and geochemical samples were made from the Upper Devonian and Lower Carboniferous to increase the understanding of the sequence. The area of outcrop is situated on the northern margin of the Canning Basin in the Kimberley Division of Western Australia (Fig. 1). Detailed fieldwork was concentrated in three areas; a narrow belt (up to 10 km wide) extending along the southwest face of the Napier and Oscar Ranges from Station Creek in the northwest to Fitzroy Crossing in the southeast, a distance of about 160 km; the Horseshoe and Burramundi Ranges, 65 km east of Fitzroy Crossing; and the Red Bluffs area, 135 km southeast of Fitzroy. METHODS OF STUDY: The outcrop areas were mapped on air photographs at a scale of 1:80,000. Comprehensive sections were measured and samples for petrological, palaeontological, and geochemical studies were collected at intervals of 1.5 m, or more, depending on outcrop. Thirty sections were measured, from which some 500 samples were collected. Detailed reports have been published or are in press dealing with the distinction of limestone's in the sequence (Radke, 1976), the conodonts (Nicoll & Druce, in prep.), and geochemistry (Druce & Radke, 1977). In addition to surface sampling, three holes were drilled to provide information on the sequence between the oldest known Carboniferous rocks and the subsurface equivalents.

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Product Specifications Coverage: Partial coverage, predominantly in northern Australia, along major transport routes, and other selected areas. About 1000 maps have been published to date. Currency: Ranges from 1968 to 2006. Coordinates: Geographical and UTM. Datum: AGD66, new edition WGS84; AHD. Projection: Universal Transverse Mercator UTM. Medium: Paper, flat copies only.

At this scale 1cm on the map represents 1km on the ground. Each map covers a minimum area of 0.5 degrees longitude by 0.5 degrees latitude or about 54 kilometres by 54 kilometres. The contour interval is 20 metres. Many maps are supplemented by hill shading. These maps contain natural and constructed features including road and rail infrastructure, vegetation, hydrography, contours, localities and some administrative boundaries. Product Specifications Coverage: Australia is covered by more than 3000 x 1:100 000 scale maps, of which 1600 have been published as printed maps. Unpublished maps are available as compilations. Currency: Ranges from 1961 to 2009. Average 1997. Coordinates: Geographical and either AMG or MGA coordinates. Datum: AGD66, GDA94; AHD Projection: Universal Transverse Mercator UTM. Medium: Printed maps: Paper, flat and folded copies. Compilations: Paper or film, flat copies only.

In northern Queensland there are several old land surfaces which are related to previous periods of erosional and depositional activity. The surfaces are of two main types - buried and exhumed unconformity surfaces formed during periods of active erosion and deposition; and terminal planation surfaces of both erosional and depositional origin which formed as stability returned at the end of each cycle of erosional activity. These terminal surfaces have generally been deeply weathered or duricrusted. The oldest landforms are exhumed unconformity surfaces of Cambrian and Mesozoic age which formed the base of the Georgina and Carpentaria Basins respectively. Three sets of unconformity and terminal surfaces are related to cycles of activity within the Cainozoic Karumba Basin. They have been correlated with surfaces elsewhere in Queensland and the Northern Territory. There are also subsidiary depositional surfaces of the current cycle, and a suite of arid landforms which has previously been treated as a surface.

Evidence is presented to show that a strong mineralogical/chemical zoning exists in seven deposits of the Cobar-Nymagee area. Characteristically, the within-deposit zoning, perpendicular to bedding, consists of a siliceous chalcopyrite-pyrrhotite eastern side with diffuse contacts against adjacent siltstone-shale host rocks, and a relatively massive sulphide, banded, pyrite-sphalerite-galena western side with sharp contacts against host rocks. Features such as these are typical of those in exhalative deposits in volcanic terrain and are taken here to indicate a similar origin in this essentially non-volcanic environment. The deposits are contained in distal turbidite facies of the Devonian Cobar Supergroup, deposited in a meridional trough bounded on its eastern flank by a possible penecontemporaneous growth fault separating the trough from an adjacent shelf area on which were deposited shallow-water marine sediments and terrestrial and marine volcanics. This volcanism and the Cobar sedimentary-exhalative deposits may be related through rifting in the area which produced the proposed growth faults and the subsequent Cobar Trough. The deposits, now in 20° discordancy to bedding, are considered to have been transposed into the prominent regional cleavage during post-ore deformation. Using the syn-sedimentary exhalative concept, two mineralised horizons and a possible tight syncline may be recognised in the CSA mine.

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Legacy product - no abstract available

Legacy product - no abstract available

At this scale 1cm on the map represents 1km on the ground. Each map covers a minimum area of 0.5 degrees longitude by 0.5 degrees latitude or about 54 kilometres by 54 kilometres. The contour interval is 20 metres. Many maps are supplemented by hill shading. These maps contain natural and constructed features including road and rail infrastructure, vegetation, hydrography, contours, localities and some administrative boundaries. Product Specifications Coverage: Australia is covered by more than 3000 x 1:100 000 scale maps, of which 1600 have been published as printed maps. Unpublished maps are available as compilations. Currency: Ranges from 1961 to 2009. Average 1997. Coordinates: Geographical and either AMG or MGA coordinates. Datum: AGD66, GDA94; AHD Projection: Universal Transverse Mercator UTM. Medium: Printed maps: Paper, flat and folded copies. Compilations: Paper or film, flat copies only.