A symposium was held at the University of Wales, Swansea in July 2007 to honour the career and achievements of Professor Michael Collins. The symposium was organised by Michael's former postgraduate students as a tribute to his contributions over the past 30 years as a scientist, teacher, mentor and friend. About 30 of the 50+ Ph.D. and M.Sc. students that Michael has supervised over the years were fortunate to attend the symposium, which offered the opportunity for all of us to learn about the many different subjects and projects that Michael supervised and to renew our friendships with the Collins family, as well as the extended, academic Collins 'family'.

Two sediment cores collected from beneath the Amery Ice Shelf, East Antarctica describe the physical sedimentation patterns beneath an existing major embayed ice shelf. Core AM01b was collected from a site of basal freezing, contrasting with core AM02, collected from a site of basal melting. Both cores comprise Holocene siliceous muddy ooze (SMO), however, AM01b also recovered interbedded siliciclastic mud, sand and gravel with inclined bedding in its lower 27 cm. This interval indicates an episode of variable but strong current activity before SMO sedimentation became dominant. 14C ages corrected for old surface ages are consistent with previous dating of marine sediments in Prydz Bay. However, the basal age of AM01b of 28250 ± 230 14C yr bp probably results from greater contamination by recycled organic matter. Lithology, 14C surface ages, absolute diatom abundance, and the diatom assemblage are used as indicators of sediment transport pathways beneath the ice shelf. The transport pathways suggested from these indicators do not correspond to previous models of the basal melt/freeze pattern. This indicates that the overturning baroclinic circulation beneath the Amery Ice Shelf (near-bed inflow-surface outflow) is a more important influence on basal melt/freeze and sediment distributions than the barotropic circulation that produces inflow in the east and outflow in the west of the ice front. Localized topographic (ice draft and bed elevation) variations are likely to play a dominant role in the resulting sub-ice shelf melt and sediment distribution.

During the Quaternary, the Mac. Robertson shelf of East Antarctica was deeply eroded by glaciers and currents exposing the underlying basement, resulting in a scalped shelf.

The Bland Basin is the broad alluviated palaeovalley of Bland Creek, a tributary of the Lachlan River in the central part of New South Wales, Australia, within the drainage basin of the Murray-Darling River System. It covers about 4000 km2 and contains up to 120 m of terrestrial sediments, interpreted as being deposited by alluvial, colluvial, lacustrine/paludal, and aeolian processes. It is undated, but is likely to be coeval with the downstream contiguous fill of the Lachlan River palaeovalley, dated elsewhere by palynology as Miocene to Recent. The southwestern part of the basin has been studied in detail using airborne geophysics (electromagnetics, magnetics, and gamma ray spectrometry) and drilling. The small erosional catchment area of the modern Basin surface has resulted in a paucity of sediment available for deposition in the Basin, but drainage base level has been driven by the rate of sedimentation of the Lachlan palaeovalley downstream of the Basin. Therefore, most of the sediment derived from the catchment has been trapped in the Basin rather than being transported downstream and into the Lachlan palaeovalley, and at times large lakes and/or swamps have formed in the central part of the Basin. The sediments in the southwest of the Basin are dominated by clay and silt, with local sand and gravel, mostly in basal gravelly sand and a sandier interval in the middle part of the sequence. Quartz silt derived from aeolian dust is a major component of the upper part of the sedimentary sequence. Geophysical responses of the sediment include high conductivity due to saline groundwater, low gamma response dominated by thorium decay emissions due to the leached nature of the sediment, and short wavelength-low amplitude magnetic anomalies resulting from local concentrations of detrital maghemite-rich gravel formed during weathering in the catchment area. Other broad valleys draining to the Lachlan River may contain similar mud-dominated Neogene basins.

This study brings together a wide range of datasets to provide a comprehensive assessment of the Pandurra Formation sedimentology and geochemistry in 3D. This record is associated with both the GA Record and the digitial data release. Sedimentology and geochemistry datasets generated this study are combined with pre-existing data to generate a 3D interpretation of the Pandurra Formation and improve understanding of how the Pandurra Formation as we see it today was deposited and subsequently post-depositionally mineralised. The digital release incorporates the underlying digital data generated this study, the final gOcad objects generated, and reference datasets from Wilson et al., 2011 as required. Study extent in eastings and northings: SW Corner (444200, 6263000) NE Corner (791409, 6726000).

This study used angular response curves of multibeam backscatter data to predict the distributions of seven seabed cover types in an acoustically-complex area. Several feature analysis approaches on the angular response curves were examined. A Probability Neural Network model was chosen for the predictive mapping. The prediction results have demonstrated the value of angular response curves for seabed mapping with a Kappa coefficient of 0.59. Importantly, this study demonstrated the potential of various feature analysis approaches to improve the seabed mapping. For example, the approach to derive meaningful statistical parameters from the curves achieved significant feature reduction and some performance gain (e.g., Kappa = 0.62). The first derivative analysis approach achieved the best overall statistical performance (e.g., Kappa = 0.84); while the approach to remove the global slope produced the best overall prediction map (Kappa = 0.74). We thus recommend these three feature analysis approaches, along with the original angular response curves, for future similar studies.

No abstract available

Disturbances characterise many natural environments - on land, a forest fire that removes a patch of old-growth trees is an example. The trees that first colonise the vacant patch may be a different species to the surrounding old-growth forest and hence, taken together, the disturbed and undisturbed forest has a higher biodiversity than the original undisturbed forest. This simple example demonstrates the intermediate disturbance hypothesis (IDH) that has applications in many natural environments. The application of IDH is significant for managers tasked with managing and conserving the biodiversity that exists in a given area. In this report we have used models of seabed sediment mobilisation to examine IDH for Australia's continental shelf environment. Although other disturbance processes may occur (eg. biological, temperature, salinity, anthropogenic, etc.) our study addresses only the physical disturbance of the seabed by waves and currents. Our study has shown that it is feasible to model the frequency and magnitude of seabed disturbance in relation to the dominant energy source (wave-dominated shelf, tide-dominated shelf or tropical cyclone dominated shelf). We focussed our attention on high-energy, patch-clearing events defined as exceeding the Shields parameter value of 0.25. Based on what is known about rates of ecological succession for different substrate types (gravel, sand, mud) we derive maps predicting the spatial distribution of a dimensionless ecological disturbance index (ED). Only a small portion of the shelf (perhaps ~10%) is characterised by a disturbance regime as defined here. Within these areas, the recurrence interval of disturbance events is comparable to the rate of ecological succession and meets our defined criteria for a disturbance regime. To our knowledge, this is the first time such an analysis has been attempted for any continental shelf on the earth.

Seasonal variations in major ions, nutrients and chlorophyll a were examined at two sites in the upper reaches of the Swan River estuary, Western Australia. Intra-annual variations between the variables were strongly influenced by seasonal riverine discharge, though major ions behaved highly conservatively across a wide range of salinity. Reduced discharge following winter produced strong density stratification that coincided with upstream salt wedge propagation and produced distinct physico-chemical identities of surface and bottom waters. Anoxia of bottom waters associated with the salt wedge region induced increased concentrations of ammonium and phosphate, especially at the deeper of the two sites. Locally variable groundwater flow may have also been important in transporting sediment porewater nutrients into the water column. The seasonality of riverine discharge produced large intra-annual variations in temperature (13-29°C) and salinity (3-30). Transient increases in turbidity occurred when the salt wedge coincided with the position of sampling locations. The subsequent flocculation process likely contributed to further oxygen consumption and nutrient regeneration from the bottom sediments, while simultaneously depositing nutrient-rich flocs with low molar N:P ratios (3-8) to the sediment surface. Nutrient ratios and absolute nutrient concentrations suggest that nitrogen is the nutrient most likely to limit phytoplankton growth over most of the year.

The deposits of heavy-mineral sands which are at present being exploited along the East Coast occur on or within a few hundred feet of the ocean beaches. The occurrence of this deposit at a distance of nearly 1.5 miles from the beach suggests the possibility that other deposits may be found at some distance from the coast line. Of incidental interest is the possibility that the deposit, which presumably was formed by wave or surf action, may be at slightly higher level than the deposits adjacent to present day beaches. The locality, examination process, origin, and nature of the deposits are discussed in this report. The results, including estimates of the quantities of heavy mineral concentrates and the grades of the mineral bearing sands, are tabulated here.