These datasets cover approximately 3360 sq km of coastal areas of Northern and South-eastern Tasmania. The project covered three areas: - Greater Hobart 1283 square km - Huon Valley 460 square km - Launceston, Burnie, Devonport 1612 square km This project, undertaken by RPS Mapping on behalf of Geoscience Australia produced accurate LiDAR and derived products to ICSM specifications and medium format digital ortho-photo mosaics.

The largest southeastern Australian earthquake this century occurred in the West Tasman Sea, 100 km east of Flinders Island, at 1948 UTC on 14 September 1946. Its epicentre was at 39.97°S, 149.35°E and its Richter magnitude ML 6.0. It was felt strongly throughout Tasmania and Gippsland, Victoria, and caused minor damage in Launceston. The isoseismal map of the earthquake is consistent with lower strong ground motion attenuation in Tasmania than in mainland southeastern Australia, and the macroseismic effects suggest amplification of seismic shaking by Tertiary lake sediments in Hobart and Launceston.

The Early Cretaceous non-marine volcaniclastic Eumeralla Formation accumulated in a rift basin on the southern margin of Australia during the break-up of eastern Gondwana. Wireline-Iog analysis and a range of sedimentary data have helped to discriminate three major basin-wide informal lithostratigraphic units in the formation. From the base of the formation they are: Eumeralla I: siltstone/mudstone/sandstone/coal; Eumeralla II: siltstone/mudstone/thin lithic sandstone; and Eumeralia III: volcaniclastic sandstone. A fourth unit - Eumeralla IV: siltstone/sandstone/coal - occurs throughout the western Otway Basin, but is absent, probably because of erosion, from the central and eastern pans of the basin. The bases of all four lithostratigraphic units are probably diachronous. The succession of lithostratigraphic units Eumeralla I- IV is interpreted as representing coal swamps and flood plains of low-energy streams; shallow and deep freshwater lakes; channel tracts and flood plains of high-energy streams; and channel tracts, flood plains and coal swamps of low- energy streams respectively. Sedimentary facies analysis of outcropping Eumeralla II and Eumeralla III in the eastern Otway Basin confirms the interpretations for these units. The basin-wide extent of the three lower lithostratigraphic units implies that a single integrated drainage system for the entire basin was established at the onset of Eumeralla Formation deposition, and persisted at least until the late Albian. This inference is supported by the close correlation between variations in lithology and depositional environments and the Aptian- Albian sea-level changes. However, intrabasinal volcanism significantly influenced sedimentation and was probably the primary control on basin drainage.

Relationships, thicknesses, and palaeocurrent and other sedimentary data applying to facies associations in Eumeralla Formation outcrops in the eastern Otway Basin distinguish at least three discrete depositional systems (A-C). Each system is characterised by high-energy fluvial flows in broad channel tracts. The multistorey sandstone bodies of system A, between Cape Otway and Apollo Bay, are up to 70 m thick and contain varying proportions of basement-derived quartzose gravel and sand intermixed with mainly volcaniclastic sand. Interchannel siltstones also up to 70 m thick separate the sandstone bodies. Palaeocurrents in system A have an overall southerly trend. This system is interpreted to represent deposition in a medial alluvial fan to proximal braided-stream system. System B occurs around Moonlight Head, and may extend southeast to Rotten Point. It is characterised by multistorey sandstone bodies up to 14 m thick separated by siltstones of similar thickness which locally contain thin coal beds, rooted horizons, and reddened soil profiles. It lacks basement-derived gravel. Palaeocurrents trend north-easterly to northwesterly. The sediments of system B accumulated on a medial to distal braid plain. Facies associations and fluvial architecture of system C, seen in outcrop north of Skenes Creek, resemble those of system B, from which it is distinguished by consistently northwest palaeocurrent vectors, a basement-derived gravel component, and the absence of debris flows and volcanic pebbles. System C also represents deposition on a braid plain or in a braided-river system. The three depositional systems are accommodated in a model for the Eumeralla Formation which suggests that its volcanic detritus was derived largely from infrarift volcanic complexes in the axial parts of the Otway rift basin, which during the Aptian-Albian lay to the south of the present coastline. A volcaniclastic apron spread northwest to northeast across the basin (system B). Elevated basement blocks shed quartzose detritus into flanking alluvial fans, the more distal parts of which mixed with volcaniclastic detritus (systems A, C). The onset of axial volcanism in the Aptian may have displaced a former westerly axial drainage towards the northern basin margin (system C).

The Bremer Basin underlies part of the upper continental slope of offshore southwest Australia. It occupies an area of 9000 km2, and contains a sedimentary pile probably 10 km thick in water depths of 200-3000 m. Though not tested by drilling, the basin is covered by a grid of seismic data. By analogy with the Eyre Sub-basin to the east, the Bremer Basin probably contains Late Jurassic to Barremian continental deposits overlain by Albian and Late Cretaceous marine deposits with a veneer of Tertiary open-marine carbonates of variable thickness. The Bremer Basin formed during the period of continental extension that preceded the breakup of Australia and Antarctica in the mid-Cretaceous. However, Triassic (?and older) extension and spreading events in the Perth Basin, a short distance to the west, are likely to have influenced its evolution. Basement structural trends in the basin indicate an old east-west-trending (?Palaeozoic) fabric that has been overprinted by north-northwesterly oriented Jurassic-Cretaceous extension and wrenching. The resultant structure is complex, particularly where the Palaeozoic and Mesozoic trends intersect. The hydrocarbon potential of the Bremer Basin is currently unknown. However, by analogy with the Eyre Sub-basin, potential source and reservoir sections can be inferred to exist, although the presence of a regional seal and a heatflow regime adequate for the generation of hydrocarbons is less certain. Potential trapping mechanisms for hydrocarbons include wrench-induced anticlines, clastic aprons adjacent to boundary and transfer faults, and stratigraphic traps within dipping Neocomian rocks beneath a major angular unconformity.

The Brunhes/Matuyama (B/M) polarity transition (0.78 Ma) marks the end of the last major period of reversed polarity of the Earth s magnetic field. Weathered regolith materials with reversed polarity chemical remanent magnetisation (CRM) must, therefore, predate the B/M transition. Reversed polarity magnetisation can be preserved in a wide variety of regolith materials in eastern Australia, particularly in oxidising environments. At Sellicks Beach and Hallett Cove near Adelaide, the B/M transition is identified in a strongly mottled unit, the Ochre Cove Formation. In Canberra, strongly weathered fan gravels on the east side of Black Mountain have a mixture of reversed and normal polarities, indicating initial weathering and deposition before 0.78 Ma and continued weathering since then. In north Queensland, a soil formed on a 2.46 Ma basalt flow has reversed polarity in the lower B horizon, indicating that, over the last 0.78 Ma, pedogenesis has had little or no effect on the secondary iron minerals carrying the magnetic remanence in that part of the profile.

Measurements of maximum trace amplitudes from 181 short- period vertical seismograms recorded at hypocentral distances of 3-1500 km from 36 earthquakes in the magnitude range 0.8 - 4.3 were used to derive a new preliminary ML scale for southeastern Australia ML = log A + (1.34±0.09)log(R/100) + (0.00055±0.00012)(R-100) + 3.13 + S where ML is local magnitude, A (mm) is equivalent Wood-Anderson trace amplitude not corrected for the measurement having been made on a vertical component, R (km) the hypocentral distance and S the station correction.

The folded Proterozoic and Palaeozoic rocks of Tasmania are host to a wide variety of mineral deposits, some of which are of world-class significance. The Proterozoic sequences host known iron ore, gold, copper and non-metallic mineralisation, but have not been intensively explored and have considerable potential for further discoveries, of both the known deposit types and a number of other sediment-hosted mineralisation types. Early Cambrian ultramafic/mafic complexes, now thought to be allochthonous, have historically given platinum-group minerals, chromite and nickel. The Middle- Late Cambrian Mt Read Volcanics, host to known world-class VHMS- gold deposits and intensively explored, are still considered to represent a prime exploration target. Disseminated zinc-lead mineralisation of possible Irish style has recently been recognised in Ordovician platform carbonate sequences in western Tasmania. Widespread mineralisation related to the intrusion of Middle Devonian- early Carboniferous granitoids includes tin-tungsten, silver-lead and slate-belt gold, and there is considerable potential for the discovery of further similar deposits. Recent advances in the recognition of structural complications caused by major thrust faulting have in some cases increased the known and perceived possibilities for potential sites of mineralisation. The late Carboniferous and younger cover rocks have traditionally been a barrier to mineral exploration, but geophysical flagging of favourable host sequences in the basement below these rocks, together with the discovery of mineralisation in basement inliers, suggests considerable mineral potential in the basement.

Integration of potential field derived architectural maps and mineral deposits in the Tasmanides

Reconstruction of the evolution of the Tasmanides in eastern Australia, with special emphasis on the 440 Ma event. Annual Review Meeting Canberra, December 2002 (i. Vos).