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No abstract available

Palaeozoic S- and I-type granites crop out extensively (~3400 km2) in the eastern and central parts of the Ordovician?Devonian Hodgkinson Province of far north Queensland. S-types dominate and form two NW to NNW trending belts, sub-parallel to major structural elements in the province. The S-types granites have been subdivided into two major (Cooktown, Whypalla) and five minor (Mount Alto, Wangetti, Tinaroo, Mount Formartine, Emerald Creek) supersuites (Bultitude & Champion, 1992; Champion & Bultitude, 1994). Most are Permian (~280 to 255 Ma); only the Emerald Creek and Mount Formartine Supersuites are older. Possible petrogenetic models for the generation of S-type granites, in general, range from crustal melting to multi-component mixing. The most obvious potential source for the north Queensland S-types is the voluminous quartzofeldspathic flysch of the Hodgkinson Province. However, most of these rocks are too mature, with chemical and isotopic signatures (?Nd values of -11 to -15 at 280 Ma), reflecting their derivation from felsic rocks similar to those exposed in the Proterozoic inliers to the west. Volcanolithic arenites, with the appropriate ?Nd value (-4.7 at 280 Ma), although not common, have been found in the far east of the province. Consequently, Champion & Bultitude (1994) proposed a source protolith consisting of both supracrustal and infracrustal arc-derived rocks, of late Proterozoic and/or early-middle Palaeozoic age. These rocks either form part of, or underlie the Hodgkinson Province assemblage. The presence of Devonian and Ordovician granites in the region, with similar chemistry and isotopic signatures to the Permian S-type granites, strongly indicates the existence of older protoliths capable of producing S-type granites. Multi-component models are more difficult to evaluate. The scarcity of 'microdioritic' enclaves and other possible indicators of mixing/mingling in the Permian S-type granites, combined with the overlapping Nd isotopic signatures for the Permian S- and I-type granites, imply magma mixing was not a significant factor. This does not rule out multiple-source components as implied by the range in ?Nd values shown by the S-types. One possibility is a multi-component protolith comprising either a heterogeneous source (such as a mixture of supracrustal and infracrustal rocks) or, alternatively, a mixed source produced during a pre-Permian magmatic event that involved significant crustal (sedimentary) contamination. Both scenarios are compatible with the preferred model protolith described above.

This paper discusses the applicability of Smalll Angle X-ray Scattering (SAXS) and Small Angle Neutron Scattering (SANS) techniques for determining the porosity, pore size distribution and internal specific surface area in coals. The method is non-invasive, fast, inexpensive and does not require complex sample preparation. It uses coal grains of about 0.7mm size mounted in standard pellets as used for petrographic studies.

Paragenesis of Fimiston Style lodes at the Golden Mile, Kalgoorlie, Western Australia (Gauthier et al)

Acid igneous rocks of northeast Queensland range in age from Precambrian to Permian.The Precambrian to Devonian Forsayth and Robin Hood Granites and the Siluro-Devonian Dumbano Granite and Dido Granodiorite form deep-level intrusions and have generally unfractionated compositions, with relatively high K/Rb and low K/Na ratios. The only significant mineralization associated with them is gold. The Proterozoic Esmeralda Granite and Croydon Volcanics and the extensively mineralized Upper Palaeozoic high-level granitic rocks and their associated volcanics are mostly highly fractionated, with high K2O, Rb, Y, Th, U, and in some cases Li and Be contents, and low K/Rb ratios. The Esmeralda Granite and Croydon Volcanics are considered to have been derived by anatexis of K-rich sialic crustal rocks, but isotopic and chemical data suggest that the Upper Palaeozoic acid magmas originated by anatexis of Rb-poor deep crustal material, possibly caused by rising basaltic or andesitic magmas derived by melting of subducted oceanic crust. Granitic rocks with associated tin mineralization, including the Esmeralda Granite and several of the more fractionated Upper Palaeozoic granitic rocks are enriched in volatile elements such as Li, Be, B and F. Sn contents are significantly higher than those of non-stanniferous granites, but lower than values reported for many Sn-granites elsewhere. No correlation of granite geochemistry with Pb/Zn or Cu mineralization was found. Published for the Bureau of Mineral Resources, Geology and Geophysics by the Australian Government Publishing Service

Legacy product - no abstract available

Legacy product - no abstract available

Six wax-sealed samples of cores were received with a request that they be tested for porosity, permeability and oil and water content. Testing was carried out by Messrs. N.V.H. Hoyling and H.S. Taylor-Rogers at the Newcastle Technical College - to the Principal and Staff of which institution grateful acknowledgment of their co-operation and utilization of their apparatus and laboratory space is made.

In connection with the search for uranium in Australia samples of mill products from producing mines have been examined for radioactivity by the Bureau. Amongst these were several samples from mines at Broken Hill. A preliminary examination showed that the uranium content of the samples was certainly much less than 0.01 per cent. To obtain more accurate data, the samples were re-examined by more sensitive methods, and the results of these are tabulated below.