Australian Geodynamics Cooperative Research Centre's integrated research program delivers a new minerals exploration strategy for industry

The Australian Geodynamics Cooperative Research Centre was an unincorporated joint venture between government organisations, universities and industry with financial support from the Commonwealth Government. Its Mission was to develop, in partnership with the minerals exploration industry, a geodynamic framework of the Australian continent, which would enhance industry's capacity to discover new world‐class deposits. The Centre has now closed after completing 7 years of integrated and innovative research. Prominent among the research outcomes are new geological, geophysical and geochronological data for key regions of Australia and new enabling technologies to collect better data or to better analyse existing data. In addition, it developed a systematic and objective methodology for synthesising data into possible exploration models that could be tested by computer analyses that simulate the geodynamic evolution of the proposed geology. If the computer simulation reproduced the same characteristics as are known to occur in a mineral deposit then the input data and exploration model are considered to be valid. They can then be used to predict whether other, as yet undiscovered deposits, occur within that area and their likely location, structure, ore grade and tonnage. This new exploration strategy can be used to reduce exploration risk and increase the rate of discovery of major new deposits.     

Photo-identification and habitat use of Atlantic humpback dolphins Sousa teuszii around the Río Nuñez Estuary in Guinea,West Africa

Ecological data for the Atlantic humpback dolphin Sousa teuszii are scant. Six on-effort Sousa teuszii sightings were recorded during 817.6?km of boat-based effort in the Río Nuñez region of Guinea during October and November 2013. Two incidental sightings were also reported. Groups comprised 1–25 animals. Photo-identification produced a minimum population estimate of 47 animals. Most sightings (n = 5) were located close (<1?km) to shore along a 5.7?km stretch of coast on the west side of Île de Taïdi, primarily over shallow, sand–mud habitat. Two very distinctive individuals were present in all four Taïdi photo-identification encounters, suggesting high site fidelity and stable associations. Two sightings occurred in the outer Río Nuñez Estuary much farther from the coast (5–12?km) but in relatively shallow water (≤15?m) over sand–mud sediment. Focal follows (n = 5: 0.2–3.8?h duration) produced 9.02?h of behavioural data. Travel (51%), foraging (39%) and feeding (9.2%) dominated, with Taïdi dolphins spending more time foraging and feeding than the outer estuary groups. Three individuals had linear-severed dorsal fins consistent with injuries from fishing line. Some management implications of variation in habitat, site fidelity and movements of Sousa teuszii groups are discussed.     

Seafloor glacial features reveal the extent and decay of the last British Ice Sheet,east of Scotland

Three‐dimensional (3D) seismic datasets, 2D seismic reflection profiles and shallow cores provide insights into the geometry and composition of glacial features on the continental shelf, offshore eastern Scotland (58° N, 1–2° W). The relic features are related to the activity of the last British Ice Sheet (BIS) in the Outer Moray Firth. A landsystem assemblage consisting of four types of subglacial and ice marginal morphology is mapped at the seafloor. The assemblage comprises: (i) large seabed banks (interpreted as end moraines), coeval with the Bosies Bank moraine; (ii) morainic ridges (hummocky, push and end moraine) formed beneath, and at the margins of the ice sheet; (iii) an incised valley (a subglacial meltwater channel), recording meltwater drainage beneath former ice sheets; and (iv) elongate ridges and grooves (subglacial bedforms) overprinted by transverse ridges (grounding line moraines). The bedforms suggest that fast‐flowing grounded ice advanced eastward of the previously proposed terminus of the offshore Late Weichselian BIS, increasing the size and extent of the ice sheet beyond traditional limits. Complex moraine formation at the margins of less active ice characterised subsequent retreat, with periodic stillstands and readvances. Observations are consistent with interpretations of a dynamic and oscillating ice margin during BIS deglaciation, and with an extensive ice sheet in the North Sea basin at the Last Glacial Maximum. Final ice margin retreat was rapid, manifested in stagnant ice topography, which aided preservation of the landsystem record. Copyright © 2008 John Wiley & Sons, Ltd.     

Determination of physical properties of a planetary surface by measuring the deceleration of a probe upon impact: Application to Titan

We report scale model laboratory experiments showing how an impact accelerometer on a planetary probe (based on the Huygens probe Phase A configuration) can provide significant information on the mechanical characteristics of the surface. In particular, solid and liquid surfaces can be discriminated. The density of liquids can in principle be determined from the peak deceleration, thereby providing a constraint on composition, although experimental uncertainties present challenges to the accuracy of this method.     

A relict ice-scoured erosion surface in the central North Sea

The interpretation of shallow seismic records from the central North Sea has revealed the existence of an irregular erosion surface within late Pleistocene sediments. A morphological study of this surface has identified two main types of relief: (1) an irregular, rough topography with depressions varying in depth from 1 to 6 m, and in width from 25 to 300 m; and (2) a much smoother topography with relatively few depressions. On a palaeobathymetric map the rough topography extends from ca. 110 to 160 m below sea level (OD), while the smoother topography extends beyond the 160 m below OD contour. This surface is interpreted as an ice-scoured erosional feature formed by the grounding of sea ice in a shallow shelf environment. The stratigraphic position of the ice-scoured surface shows it to be a relict late Weichselian feature formed at ca. 17,000–18,000 B.P.     

Pleistocene glacial history of the NW European continental margin

In this paper new and previously published data on the Pleistocene glacial impact on the NW European margin from Ireland to Svalbard (between c. 48°N–80°N) are compiled. The morphology of the glaciated part of the European margin strongly reflects repeated occurrence of fast-moving ice streams, creating numerous glacial troughs/channels that are separated by shallow bank areas. End-moraines have been identified at several locations on the shelf, suggesting shelf-edge glaciation along the major part of the margin during the Last Glacial Maximum. Deposition of stacked units of glacigenic debris flows on the continental slope form fans at a number of locations from 55°N and northwards, whereas the margin to the south of this is characterised by the presence of submarine canyons. Glaciation curves, based primarily on information from the glacial fed fan systems, that depict the Pleistocene trends in extent of glaciations along the margin have been compiled. These curves suggest that extensive shelf glaciations started around Svalbard at 1.6–1.3 Ma, while repeated periods of shelf-edge glaciations on the UK margin started with MIS 12 (c. 0.45 Ma). The available evidence for MIS 2 suggest that shelf-edge glaciation for the whole margin was reached between c. 28 and 22 ¹⁴C ka BP and maximum positions after this were more limited in some regions (North Sea and Lofoten). The last glacial advance on the margin has been dated to 15–13.5 ¹⁴C ka BP, and by c. 13 ¹⁴C ka BP the shelf areas were completely deglaciated. The Younger Dryas (Loch Lomond) advance reached the coastal areas in only a few regions.     

Problems associated with seismic facies analysis of diamicton-dominated,shelf glacigenic sequences

Diamicton-dominated shelf glacigenic sequences are characterized on high-resolution seismic records by a structureless to chaotic acoustic texture, often with abundant hyperbolic (point-source) reflections. Existing depositional models, based primarily on seismic data, have been constructed on the basis that this acoustic signature is indicative of subglacial till. However, borehole data from the UK continental shelf indicate that glaciomarine facies are also present. Thus, while this acoustic character may be indicative of diamicton lithofacies, it should not be taken as a predictive genetic indicator of a specific depositional process.     

Late Cenozoic prograding wedges on the NW European continental margin: their formation and relationship to tectonics and climate

During late Pliocene to Pleistocene times, prominent prograding wedges were deposited along the continental margin of NW Europe, resulting in seaward shelf break migration of up to 150 km. Much of the sediment accumulation occurred marginal to the former mid- to high-latitude ice sheets. The geographical distribution, and stratigraphical and chronological data may suggest that the instigation of the wedges was variously related to tectonic uplift as well as a response to the late Pliocene to Pleistocene climate deterioration and onset of major northern hemisphere glaciations. The onset of wedge growth on the NW UK and Irish margins was initiated at about 4 Ma in response to tectonic tilting of the margin in that region. However, glacially derived sediments here comprise a significant proportion of the wedges, especially since 0.44 Ma. For the Faroe margin, no detailed chronology is available; however, it may be inferred that onset of glacigenic wedge growth here did not post-date that observed on the NW UK and Irish margins. Offshore Norway, wedge growth has largely occurred since ca. 2.7 Ma in response to northern hemisphere glaciations, also recording a major change in sediments transport routes at 0.8–1.1 Ma (reflecting larger Fennoscandian Ice Sheets). Presently, it is uncertain whether the glacigenic wedge growth was preceded by a fluvial phase (in response to uplift) in this area. In the western Barents Sea, an early phase of wedge growth was (glacio) fluvial in character. Off western Spitsbergen, the development was similar to that of the Barents Sea although the glacigenic wedge-growth phase may have started somewhat earlier.The wedges commonly display gently inclined seaward prograding clinoforms, and transparent to chaotic internal acoustic facies. Sampling of their sediments reveals that they are mainly composed of glacigenic diamicton interbedded with marine and glaciomarine sediments that, to various extents, have been affected by bottom-current action. The clinoforms of these wedges vary in geometry from oblique to sigmoidal, and they also show varying degrees of aggradation throughout their development. The resulting stratal stacking pattern can be attributed to a combination of variations in sediment supply, sedimentary processes, and accommodation space, the latter being a function of tectonic movements and/or loading induced subsidence as well as eustatic sea-level fluctuations.     

Valley asymmetry: Evidence for periglacial activity in the central North Sea

Present-day open valleys with distinct asymmetric profiles have been studied from the central North Sea. The bulk of the valleys exhibit steep north-facing and shallow south-facing slopes. This asymmetry is ascribed to preferential slumping of the south-facing slope under periglacial climatic conditions. Exceptions to the regional asymmetric trend are probably the result of more localized factors such as fluvial and microclimatic processes and the effects of local geology. The recognition of this type of within-valley asymmetry associated with slumping in buried valleys within the Quaternary sequence may be indicative of former periglacial activity.