Total contribution of six recently discovered submerged coral reefs in northern Australia to Holocene neritic CaCO3, CO2, and C is assessed to address a gap in global budgets. CaCO3 production for the reef framework and inter-reefal deposits is 0.26-0.28 Mt which yields 2.36-2.72 x105 mol yr-1 over the mid- to late-Holocene (<10.5 kyr BP); the period in which the reefs have been active. Holocene CO2 and C production is 0.14-0.16 Mt and 0.06-0.07 Mt, yielding 3.23-3.71 and 5.32-6.12 x105 mol yr-1, respectively. Coral and coralline algae are the dominant sources of Holocene CaCO3 although foraminifers and molluscs are the dominant constituents of inter-reefal deposits. The total amount of Holocene neritic CaCO3 produced by the six submerged coral reefs is several orders of magnitude smaller than that calculated using accepted CaCO3 production values because of very low production, a 'give-up' growth history, and presumed significant dissolution and exports. Total global contribution of submerged reefs to Holocene neritic CaCO3 is estimated to be 0.26-0.62 Gt or 2.55-6.17 x108 mol yr-1, which yields 0.15-0.37 Gt CO2 (3.48-8.42 x108 mol yr-1) and 0.07-0.17 Gt C (5.74-13.99 x108 mol yr-1). Contributions from submerged coral reefs in Australia are estimated to be 0.05 Gt CaCO3 (0.48 x108 mol yr-1), 0.03 Gt CO2 (0.65 x108 mol yr-1), and 0.01 Gt C (1.08 x108 mol yr-1) for an emergent reef area of 47.9 x103 km2. The dilemma remains that the global area and CaCO3 mass of submerged coral reefs are currently unknown. It is inevitable that many more submerged coral reefs will be found. Our findings imply that submerged coral reefs are a small but fundamental source of Holocene neritic CaCO3, CO2, and C that is poorly-quantified for global budgets.

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.

Geoscience Australia contributed a multi-satellite, multi-year weekly time series to the International DORIS Service combined submission for the construction of International Terrestrial Reference Frame 2008 (ITRF2008). This contributing solution was extended to a study of the capability of DORIS to dynamically estimate the variation in the geocentre location. Two solutions, comprising different constraint configurations of tracking network, were undertaken. The respective DORIS satellite orbit solutions (SPOT-2, SPOT-4, SPOT-5 and Envisat) were verified and validated by comparison with those produced at the Goddard Space Flight Center (GSFC), DORIS Analysis Centre, for computational consistency and standards. In addition, in the case of Envisat, the trajectories from the GA determined SLR and DORIS orbits were compared. The results for weekly dynamic geocentre estimates from the two constraint configurations were benchmarked against the geometric geocentre estimates from the IDS-2 combined solution. This established that DORIS is capable of determining the dynamic geocentre variation by estimating the degree one spherical harmonic coefficients of the Earth's gravity potential. It was established that constrained configurations produced similar results for the geocentre location and consequently similar annual amplitudes. For the minimally constrained configuration Greenbelt - Kitab, the mean of the uncertainties of the geocentre location were 2.3, 2.3 and 7.6 mm and RMS of the mean uncertainties were 1.9, 1.2 and 3.5 mm for the X, Y and Z components respectively. For GA_IDS-2_Datum constrained configuration, the mean of the uncertainties of the geocentre location were 1.7, 1.7 and 6.2 mm and RMS of the mean uncertainties were 0.9, 0.7 and 2.9 mm for the X, Y and Z components respectively. The mean of the differences of the two DORIS dynamic geocentre solutions with respect to the IDS-2 combination were 1.6, 4.0 and 5.1 mm with an RMS of the mean 21.2, 14.0 and 31.5 mm for the Greenbelt - Kitab configuration and 4.1, 3.9 and 4.3 mm with an RMS 8.1, 9.0 and 28.6 mm for the GA_IDS-2_Datum constraint configuration. The annual amplitudes for each component were estimated to be 5.3, 10.8 and 11.0 mm for the Greenbelt - Kitab configuration and 5.3, 9.3 and 9.4 mm for the GA_IDS-2_Datum constraint configuration. The two DORIS determined dynamic geocentre solutions were compared to the SLR determined dynamic solution (which was determined from the same process of the GA contribution to the ITRF2008 ILRS combination) gave mean differences of 3.3, -4.7 and 2.5 mm with an RMS of 20.7, 17.5 and 28.0 mm for the X, Y and Z components respectively for the Greenbelt - Kitab configuration and 1.1, -5.4 and 4.4 mm with an RMS of 9.7, 13.3 and 24.9 mm for the GA_IDS-2_Datum configuration. The larger variability is reflected in the respective amplitudes. As a comparison, the annual amplitudes of the SLR determined dynamic geocentre are 0.9, 1.0 and 6.8 mm in the X, Y and Z components. The results from this study indicate that there is potential to achieve precise dynamically determined geocentre from DORIS.

On 22 December 1987 a shallow magnitude 4.9 earthquake occurred in western Victoria where there is no record of previous seismic activity. It was felt over a remarkably wide area of Victoria and South Australia and caused minor damage in the epicentral area. There were no foreshocks and only ten aftershocks were recorded on the nearest seismograph, near Willalooka in South Australia. All ten occurred within five days of the mainshock. The earthquake occurred in a seismic zone that extends over a 500 km wide belt along the entire eastern coast of Australia linking the Southeast Seismic Zone of South Australia with the Eastern Highlands Zone through Queensland, New South Wales, Victoria and Tasmania. Its focal mechanism, a thrust with a principal stress directed east-west, is typical of earthquakes in the Lachlan Fold Belt.

Earthquake risk maps of Australia were prepared using a computer program which selected events from a regional earthquake file and calculated maximum values of acceleration, velocity and intensity at the nodes of a half degree grid, using a scaling rule of the Kanai form Y = aebmR-c. The parameters a, b and c determined by Esteva and Rosenblueth for the Western United States of America were used. For each node on the grid the Y values were plotted against the return period (years) on logarithmic scales. The results, which were compiled from the period 1960-1972, were extrapolated to give expected values of ground acceleration, ground velocity and intensity for a fifty-year return period. These values were plotted and contoured at the following zone boundaries: [see pdf for details]. The following nine Zone-2 areas together with the maximum expected ground accelerations for a fifty-year return period were delineated: Meckering (12m/s2); Gippsland (5m/s2); Picton (4.9m/s2); Cape Otway (4.5m/s 2); Broome (4.2m/s 2); Lower Eyre Peninsula (3.8m/s2, excludes Port Lincoln); east of Carnarvon (3.2m/s2), and the Simpson Desert (4.0m/s2).

Isotopic ages of Proterozoic acid volcanics and associated granitic intrusions in the northeast and southwest part of The Granites-Tanami region are reported and discussed. In the northwest, within The Granites-Tanami Block, the Mount Winnecke Formation, which includes acid volcanics that were probably erupted underwater, is intruded and weakly metamorphosed by the high-level Winnecke Granophyre. The acid volcanics and intrusives have similar major element compositions, and this, together with the field evidence, indicates that they are probably comagmatic. Rb-Sr total rock and mineral data for the Winnecke Granophyre yield an isochron indicating an age of 1802 ± 15 m.y. and an initial Sr87/Sr86 of 0.7074 ± 0.0036. Isotopic data for the lavas of the Mount Winnecke Formation give a preferred age of 1808 ± 15 m.y. and an initial Sr87 /Sr86 of 0.7052 ± 0.0038. In the southwest, at the western extremity of the Arunta Block, another acid volcanic suite, belonging to the Pollock Hills Formation, is intruded and weakly metamorphosed by the Mount Webb Granite. As in the northeast, the volcanics and intrusives have similar major element compositions, and are considered to be comagmatic. Combining Rb-Sr isotopic data from both the volcanics and intrusives yields an isochron indicating an age of 1526 ± 25 m.y. and an initial Sr87/Sr86 of 0.711 ± 0.004. These rocks are appreciably younger than those in the northeast. The acid igneous rocks in the southwest also postdate three other newly dated granitic units in The Granites-Tanami Block - the Lewis Granite, 1720 ± 8 m.y.; the Slatey Creek Granite, 1770 ± 55 m.y.; and The Granites Granite, 1780 ± 24 m.y. - and are younger than the Gardiner Sandstone, the basal unit of the Birrindudu Group, which unconformably overlies The Granites-Tanami Block. K-Ar and Rb-Sr ages determined on glauconite from the Gardiner Sandstone show little consistency, due evidently to partial loss of radiogenic daughter products, but a preferred K-Ar age of 1560 ± 20 m.y. is considered a reasonable minimum estimate for the age of sedimentation and diagenesis in the unit.

A recently discovered Templetonian (Middle Cambrian) trilobite fauna, with affinity to that of the Beetle Creek Formation of western Queensland, is reported from pebbles derived from the Elcho Island Formation (Wessel Group) on Elcho Island, in the Arafura Basin, northern Australia. Consequently, a previously determined isotopic age of 790 m.y., on glauconite from the Elcho Island Formation, is now clearly much greater than the age of deposition of the formation, and the age of the occurrence of Skolithos at the base of the Wessel Group (Buckingham Bay Sandstone) can be reconsidered as Early or early Middle Cambrian, rather than late Proterozoic. Regional correlation of the Buckingham Bay Sandstone and Raiwalla Shale of the Arafura Basin with the Bukalara Sandstone and Cox Formation of the McArthur River region is reiterated on the basis of rock types and presence of the trace fossil Skolithos.

Little deformed Cretaceous sedimentary rocks underlie 1 500 000 km^2 of eastern Australia. Depositional environments in them range from freshwater to shallow marine. The Neocomian and Aptian sequences are quartz-rich, and the Albian and Cenomanian sequences are quartz-poor. The older sequences were derived largely from nearby basement rises, while the younger sequences were probably derived from Cretaceous volcanics forming a mountain range to the northeast. Glauconie is common in marine and paralic sequences. An epicontinental sea, with seaways to the north and east, covered the basins in the late Aptian, but the eastern seaway closed during an early Albian regression. A second transgressive-regressive cycle, in the late Albian, was virtually confined to the Eromanga Basin. Collectively the two transgressions and regressions were spread over about 20 million years. The present Baltic Sea is thought to provide a small-scale depositional model for the sequences under consideration: of an epicontinental sea in a cool climate, in which the salinity, the number of planktonic organisms, and the variety of benthonic organisms, decrease away from the ocean. The shallowness of the sea and its entrances mean that it is very susceptible to major environmental changes, caused by such factors as eustatic changes of sea level. The area had a gentle northwesterly regional tilt during the Cretaceous, but mid-Tertiary movements changed this to southwesterly. Despite subsequent erosion, as much as 2000 m of Cretaceous sediment is preserved in the Eromanga Basin, and 700 min the Surat Basin.

Abstracts: 'Models of sulphide ore formation in sedimentary rocks', Gustafson, L.B.; 'Metal sources and fixation in some stratiform deposits' Lambert, I.B.; 'addle dolomite gangue: an indicator of epigenetic mineralisation in sediments', Radke, B.M.; 'Lead isotopic systematics of sediment-hosted Pb-Zn deposits', Vaasjoki, M. and Gulson, B.L.; 'Mechanisms of sulphide deposition in sediment-hosted exhalative lead-zinc deposits', Russell, M.J., Solomon, M. and Walshe, J.L.; 'The Coxco deposit: lead-zinc mineralisation in a Precambrian karst cavern system', Walker, R.N.; 'Stratiform copper mineralisation - settings and environments', Rowlands, N.; 'Mount Isa copper orebodies - evidence against a sedimentary origin', Perkins, W.G.; 'Relationship of copper to lead-zinc ore bodies and source of copper at Mount Isa, Queensland', Gulson, B.L., Perkins, W.G. and Mizon, K.J.; 'Chemical and mineralogical constraints on the genesis of mineralisation in the Mount Gunson region, South Australia', Knutson, J.; 'Diagenetic mineralisation in the Wollogorang Formation McArthur Basin, Northern Territory', Jackson, M.J.; 'Studies of modern sedimentary environments as an exploration aid', van der Borch, C.; 'Distribution of metals in sediments', Warren, L.J.; 'Determination of dissolved sulphide in marine sediments', Hauser, J.; 'Sulphate reduction in coastal marine sediments: magnitude and controls', Wiebe, W.J.; 'Sulphate reduction in modern sediments and implications for ore formation', Skyring, G.W.; 'Early diagenesis in some deep sea sediments, northeast Indian Ocean', Cook, P.J., Chambers, L.A. and Trudinger, P.A.; 'Sulphur isotope distributions and the depositional environment', Chambers, L.A.; 'Precambrian sulphur isotopes: implications for the global sulphur cycle', Donnelly, T.H.; 'Diagenesis of organic matter in shallow marine sediments: an experimental study', Bubela, B; 'Sources of organic matter in Precambrian sediments', Walter, M.R.

A commonly cited model for the genesis of stratiform Cu deposits that lack either igneous or hydrothermal associations has been tested in modern environments, on the northeastern shore of Spencer Gulf, South Australia. In this area, saline continental redbed groundwaters mobilise Fe and Mn from the aquifer sediments and transport these metals to coastal Holocene carbonate complexes. There they may precipitate in sediments in ephemeral lakes or around springs formed by the emerging ground waters. The continental groundwaters are generally acidic and oxidising, and they discharge mainly in the supratidal zone, remote from the major areas of bacterial sulphate reduction in the intertidal zones of the sedimentary complexes. Conversion of Fe in the groundwaters to sulphides is not widespread, but occurs if the influence of the ground waters is attenuated by seasonal decrease in flow rate or by interaction with the alkaline, reducing marine carbonate environment of the peritidal zones. The Spencer Gulf investigations strongly support the contention that terrestrial groundwaters of suitable pH, Eh, and salinity for the transport of high concentrations of Cu, Pb, and Zn may be generated in semi-arid climates, and that these groundwaters are capable of mobilising large quantities of metals held in Fe-oxide grain coatings. The formation of a stratiform metal deposit zoned in accordance with metal sulphide solubilities is more difficult to envisage. The absence from the supratidal sequence of a thick deposit of organic matter capable of sustaining bacterial sulphate reduction means that the metals are more likely to be removed from solution by adsorption onto the marine carbonates, or by oxidation and precipitation as oxides or hydroxides.