Titles in this newsletter: Nutrients from sediments: Implications for algal blooms in Myall Lakes More sources for gas and oil in Perth Basin: Study highlights potential for multiple petroleum systems The importance of the 'backend' to online delivery of geoscience information Minerals laboratory staff develops new ICP-MS preparation method Bonaparte Basin: Geochemical characteristics of hydrocarbon families and petroleum systems Customised regolith maps incorporate hydrologic modelled attributes for geochemical exploration Publications involving AGSO authors:May-November 2000

The satellite images below show the dramatic effect on the land of recent heavy rain, causing floodwaters to inundate south-west Queensland. This area is known as the Channel Country and has an extensive braided river system which includes the Georgina River, the Diamantina River and Cooper Creek. Excess water from this area generally feeds into the Lake Eyre system which is a vast drainage basin in Australia's arid interior. Flooding of the magnitude visible on the satellite images can cause Lake Eyre to fill up - something which occurs very rarely.

This second edition, coming after the first one published in 1990, has been entirely revised in order to show a clear distinction between sedimentary, volcanic extrusive, and endogenous dated formations. The geology of the oceans has been also updated according to the most recent magnetic and satellite-gravimetric data. Positions of the main volcanoes and meteoritic craters were added to the map. The new cartographic conception of the map allows a rapid visual reconstruction of the main plates and sub-plates of the global tectonics. This geological wall map is the only one existing today that presents the world geological setting at a glance. There is a clearly distinguishable contrast between the continents - whose rocks may attain an age up to nearly 4 billion years&endash; and the oceanic crust - whose age does not exceed 200 million years.

This map is part of the series that covers the whole of Australia at a scale of 1:250 000 (1cm on a map represents 2.5 km on the ground) and comprises 513 maps. This is the largest scale at which published topographic maps cover the entire continent. Each standard map covers an area of 1.5 degrees longitude by 1 degree latitude or about 150 kilometres from east to west and 110 kilometres from north to south. There are about 50 special maps in the series and these maps cover a non-standard area. Typically, where a map produced on standard sheet lines is largely ocean it is combined with its landward neighbour. These maps contain natural and constructed features including road and rail infrastructure, vegetation, hydrography, contours (interval 50m), localities and some administrative boundaries. The topographic map and data index shows coverage of the sheets. Product Specifications Coverage: The series covers the whole of Australia with 513 maps. Currency: Ranges from 1995 to 2009. 95% of maps have a reliability date of 1994 or later. Coordinates: Geographical and either AMG or MGA (post-1993) Datum: AGD66, GDA94, AHD. Projection: Universal Traverse Mercator (UTM) Medium: Paper, flat and folded copies.

This map is part of the series that covers the whole of Australia at a scale of 1:250 000 (1cm on a map represents 2.5 km on the ground) and comprises 513 maps. This is the largest scale at which published topographic maps cover the entire continent. Each standard map covers an area of 1.5 degrees longitude by 1 degree latitude or about 150 kilometres from east to west and 110 kilometres from north to south. There are about 50 special maps in the series and these maps cover a non-standard area. Typically, where a map produced on standard sheet lines is largely ocean it is combined with its landward neighbour. These maps contain natural and constructed features including road and rail infrastructure, vegetation, hydrography, contours (interval 50m), localities and some administrative boundaries. The topographic map and data index shows coverage of the sheets. Product Specifications Coverage: The series covers the whole of Australia with 513 maps. Currency: Ranges from 1995 to 2009. 95% of maps have a reliability date of 1994 or later. Coordinates: Geographical and either AMG or MGA (post-1993) Datum: AGD66, GDA94, AHD. Projection: Universal Traverse Mercator (UTM) Medium: Paper, flat and folded copies.

This map is part of the series that covers the whole of Australia at a scale of 1:250 000 (1cm on a map represents 2.5 km on the ground) and comprises 513 maps. This is the largest scale at which published topographic maps cover the entire continent. Each standard map covers an area of 1.5 degrees longitude by 1 degree latitude or about 150 kilometres from east to west and 110 kilometres from north to south. There are about 50 special maps in the series and these maps cover a non-standard area. Typically, where a map produced on standard sheet lines is largely ocean it is combined with its landward neighbour. These maps contain natural and constructed features including road and rail infrastructure, vegetation, hydrography, contours (interval 50m), localities and some administrative boundaries. The topographic map and data index shows coverage of the sheets. Product Specifications Coverage: The series covers the whole of Australia with 513 maps. Currency: Ranges from 1995 to 2009. 95% of maps have a reliability date of 1994 or later. Coordinates: Geographical and either AMG or MGA (post-1993) Datum: AGD66, GDA94, AHD. Projection: Universal Traverse Mercator (UTM) Medium: Paper, flat and folded copies.

Palaeomagnetic, rockmagnetic and magnetic fabric results are presented for a Carboniferous (Visean to Westphalian) succession of felsic, mainly ignimbritic, volcanic and volcaniclastic rocks from the Rocky Creek Block of the northern Tamworth Belt, southern New England Orogen. Detailed thermal demagnetization of 734 samples from 64 sites has shown three groups of magnetic components with low (LT: up to 300 degrees C), intermediate (IT: 300 to 600 degrees C) and high (HT: mainly 500 to 680 degrees C) unblocking temperature ranges. Analysis and interpretation of component directions have established well-defined primary magnetization results fro 29 sites and evidence for four magnetic overprint phases.The overprints are of widespread (a,c) or localized (b,d) occurrence and are attributed to: a mid_tertiary weathering event (a: mainly LT); or to fluid movements (b,c,d) associated with either Late Cretaceous opening of the Tasman Sea (b: mainly HT); or to thrusting during the Middle Triassic main phase of the Hunter_Bowen Orogeny (c: mainly IT); or to latest Carboniferous - Early Permian formation of the Bowen-Gunnedah-Sydney Basin system (d: IT,HT). Rockmagnetic (Lowrie-Fuller test, IRM acquisition, Lowrie-test, low- and high-temperature susceptibility cycling) and palaeomagnetic analyses indicate predominance of magnetite carriers with main unblocking temperatures ranging from 400 to between 500 and 580 degrees C, and less prevalent presence of hematite carriers with unblocking temperature ranges generally up to 640 degrees C and for some sites up to 680 degrees C. Multidomain (MD-) magnetite is prevalent in the volcaniclastic rocks. Most of the volcanic rocks with well-defined primary magnetization components show evidence for single domain (SD-) magnetite with no, or only limited, presence of MD-magnetite. See paper for remainder of abstract

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