Part-page item of matters related to stratigraphy. This column discusses informal units, the role of authors and reviewers, and is the 50th Stratigraphic Column produced by the Australian Stratigraphy Commission. Journal ISSN 0312 4711

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This record describes digital data compilation product, where several individual items are grouped for delivery on single CD-ROM. Content and number of items included in the compilation package can vary, depending on size of the individual items. The contents of this CD-ROM are as follows: Catalog # Title 34684 Mount Isa geology 250k 36813 Mount Isa Inlier lithostratigraphy and chronostratigraphy 100k 21949 Mount Isa Inlier and Environs 1:500 000 GIS package (version 1.2) 500k

The national mineral deposits dataset covers 60 commodities and more than 1050 of Australia's most significant mineral deposits - current and historic mines and undeveloped deposits. This release adds more than 100 new deposits to the previous release of OZMIN plus upgraded resource and production figures.

Biostratigraphy is the branch of stratigraphy that uses fossils to establish relative ages of rock and correlate successions of sedimentary rocks within and between depositional basins. A biozone is an interval of geologic strata characterised by certain fossil taxa. Such intervals are often defined by the first appearances (range bases), apparent extinctions (range tops/last appearances), or abundances of fossil index species. These key index species should be relatively abundant, short-lived taxa that are easy to recognise and as geographically widespread as possible. Widely used fossil groups include brachiopods, conodonts, dinoflagellate cysts, foraminifera, graptolites, nannofossil, spores and pollen and trilobites. Zonal schemes based on several different fossil groups can be used in parallel, and the zones can be calibrated to the absolute geological timescale using tie points to rocks which have been radio-isotopically dated.

This documentation manual for the Mount Isa dataset provides description of AGSOs mineral deposit database (OZMIN) - it's structure, the main data and authority tables used by OZMIN, database table definitions, details on the Microsoft Access version of the database and a listing of those deposits in the Mount Isa dataset

Mount Marumba covers the central part of Arnhem Land, which is occupied mainly by the Katherine River, Mount Rigg and Roper Groups of the Palaeoproterozoic to Mesoproterozoic McArthur Basin succession. These units consist of marine and non-marine clastics, carbonates, and lesser volcanics, that are extensively intruded by dolerite and some microgranite. Recent mapping and associated structural, geophysical, geochemical and geochronological studies have resulted in a number of important new findings: (1) The Jimbu Microgranite intruded the Katherine River Group at ~1710 Ma, causing updoming of surrounding sediments to form a number of structural domes. (2) An age of 1324 Ma has been obtained from the Derim Derim Dolerite, intruding the Roper Group, that provides improved constraints on the ages of sedimentation and deformation. (3) An aeolian facies has been recognised within the Gundy Sandstone. (4) The former Kombolgie Formation has been elevated to a Subgroup, subdivded into component formations, and extended upwards to include the McKay Sandstone. (5) A major impact structure, the Gulpuliyul Structure, was formed between ~1600 and 1324 Ma.The mapping and interpretation took advantage of the full complement of regional gravity, airborne magnetic and gamma-ray spectometric datasets now available. Concealed dykes, lineaments and sill edges are overprinted on the surface geology in magenta. In addition, the map features 1:1 000 000-scale marginal figures of an enhanced total magnetic intensity image and a gamma-ray spectroscopy image. Two cross-sections highlight the salient features of the stratigraphy and structure. The 84-page Explanatory Notes presents descriptions of the geology in some detail, in sections on the regional geological setting, stratigraphy, geophysics, structure, geological history and economic geology. The text is supported by several tables and numerous black-and-white photographs and line drawings, as well as some full-colour images.