Recently acquired seismic reflection and gravity potential field data was used to investigate the distribution of volcanic facies and large scale structural architecture of the Mentelle Basin, located on the southwestern margin of Australia. Isochron and seismic facies maps were used to identify the thickness and distribution of volcanic facies. These maps show that volcanism is generally confined to the Western Mentelle Basin, with two distinct areas of thick volcanic deposits occurring to the centre and north of the area. Two and three dimensional gravity forward models were created in IGMAS+. Two dimensional gravity modelling shows that the crust is extremely thin in the Western Mentelle (c.10km), associated with two mantle highs observed to the north and centre of the Western Mentelle. The crust thickens from the Eastern Mentelle (>20km) towards mainland Australia and the Naturaliste Plateau. The two modelled mantle highs coincide with the two seismically defined areas of thick volcanic deposits. Analogue models indicate that rift related volcanism is generally confined to the locus of extension where the pressure is lowest. Thus results of gravity modelling and seismic interpretation in this study indicate that Jurassic - Cretaceous extension was focussed in the Western Mentelle. This conclusion conforms to models of rift related basin formation, where the flanks of the basin are uplifted; an angular unconformity in the Eastern Mentelle may support the occurrence of rift-flank uplift in this area as a result of asthenospheric rise and rifting while the deposition of volcanic material was focussed in the Western Mentelle.

An informative guidebook outlining the spectacular geological features of the Warrumbungles and their origins. Discover the volcanic evolution of this area over the last 17 million years. Illustrated with cross-sections, photographs and maps and includes a glossary of relevant terms. Suggested walking trails included with their geological features and points of interest.

Legacy product - no abstract available

Legacy product - no abstract available

Legacy product - no abstract available

Legacy product - no abstract available

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Legacy product - no abstract available

The Mellish Rise lies off northeast Australia, trends northeast overall, and is about 700 km long and 300 km wide. Much of it lies in Australian territory. In the southwest, near Mellish Reef, a large area is shallower than 2500 m, but further northeast there are only occasional comparably shallow highs. To the northwest the Coral Sea Basin and the Louisiade Trough, and to the southeast the narrow South Rennell Trough and the west D'Entrecasteaux Basin are all deeper than 3500 m. The rise also lies to the north of another fragment of continental crust, the Kenn Plateau. The Mellish Rise and Kenn Plateau have been the subject of recent geoscience surveys of R.V. Southern Surveyor, undertaken by Geoscience Australia, to determine their composition. The emphasis in this report is on the Mellish Rise survey (SS02/2005), during which 1189 km of multichannel seismic data were acquired using a 24 channel, 600 m long streamer and two GI airguns. In addition, multibeam and single beam bathymetry, and magnetic data were recorded. Forty-four dredge sites and five core stations were occupied to investigate the geology, and the great bulk of these deployments were successful. Dredge sites were concentrated on the Mellish Rise and Kenn Plateau, but are also included the Louisiade Plateau. Foraminiferal, nannofossil and petrological studies have been carried out on suitable rocks and sediments.

Large atmospheric acoustic sources such as: volcanic eruptions, bolides (terminating meteorite explosions), the ocean surface, chemical and nuclear detonations generate copious quantities of infrasound (low frequency sound) that can propagate several thousand kilometres. Using the appropriate recording equipment, infrasound from various sources can be detected and used to infer certain knowledge about the source mechanism or atmosphere through which it travelled. Each year an Infrasound Technology Workshop is organised to provide researchers from various international institutions the opportunity to meet with colleagues and present current research results in an informal setting. The Infrasound Technology Workshop 2004 was hosted by Geoscience Australia in Hobart, Tasmania from 29 November to 3 December 2004. The Workshop was organised in cooperation with the Provisional Technical Secretariat of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) in Vienna. Listed below is the complete list of abstracts submitted to the general infrasound session in author's surname order. 28 abstracts were submitted for this workshop. A special Volcano Infrasound session was held at the Workshop, see Geocat #69616 to view abstracts.