http://hdl.handle.net/2440/12035 2013-05-22T00:43:00Z 2013-05-22T00:43:00Z Twidale, Charles Rowland http://hdl.handle.net/2440/77389 2013-05-06T01:30:40Z 2011-12-31T13:30:00Z

Title: Landscape analysis: derivation and rediscovery of ideas Author: Twidale, Charles Rowland

2011-12-31T13:30:00Z Kakar, M. Ishaq Collins, Alan Stephen Mahmood, Khalid Foden, John David Khan, Mehrab http://hdl.handle.net/2440/75258 2013-02-04T04:30:42Z 2011-12-31T13:30:00Z

Title: U-Pb zircon crystallization age of the Muslim Bagh ophiolite: enigmatic remains of an extensive pre-Himalayan arc Author: Kakar, M. Ishaq; Collins, Alan Stephen; Mahmood, Khalid; Foden, John David; Khan, Mehrab

2011-12-31T13:30:00Z van der Hoek, Benjamin Graham Hill, Steven Matthew Dart, Robert Charles http://hdl.handle.net/2440/75257 2013-02-04T04:30:39Z 2011-12-31T13:30:00Z

Title: Calcrete and plant inter-relationships for the expression of concealed mineralization at the Tunkillia gold prospect, central Gawler Craton, Australia Author: van der Hoek, Benjamin Graham; Hill, Steven Matthew; Dart, Robert Charles Abstract: Transported and typically weathered material that extends over much of Australia presents a challenge for the successful application of surficial geochemical exploration methods. The Tunkillia Au-prospect in the Gawler Craton, South Australia provides a case study where unconsolidated and potentially laterally transported aeolian and alluvial sediments overlie a deeply weathered profile with variable supergene and primary Au mineralization at depths typically exceeding 40 m. The Tunkillia Au prospect was discovered through a regional calcrete sampling program, but elevated Au concentrations in this material do not always express underlying mineralization, such is the case at Tomahawk, an area of elevated Au in calcrete results overlying limited, low grade mineralization. The distribution and sampling accessibility of calcrete is also not continuous across the landscape, where in this region young siliciclastic linear dune ridges bury older calcrete that are otherwise exposed or only at shallow depths in dune swales or across sheetwash plains. Vegetation cover is more continuous across this landscape and is dominated by several main species. Sampling of dominant plant species: Casuarina pauper, and Eucalyptus concinna, has been conducted across Tomahawk where some sites of elevated Au in calcrete have been drilled. Results show a limited spatial association between calcrete geochemistry and plant biogeochemistry. This demonstrates that plant sampling is able to express low grade, discrete areas of buried Au mineralization typically on the scale of tens of metres, whereas the expression provided from calcrete is more levelled, and typically representative of larger areas, especially when they have formed within transported detritus host materials. It is recommended that although plant biogeochemistry and calcrete geochemistry may have their strengths and weaknesses, such as scale constraints, in regional geochemical exploration programs when these methods are integrated they potentially provide a more comprehensive and widely available geochemical exploration assessment across a wider range of regolith-landform settings.

2011-12-31T13:30:00Z Sappenfield, Aaron Droser, Mary L. Kennedy, Martin John McKenzie, Ryan http://hdl.handle.net/2440/75246 2013-02-04T03:30:35Z 2011-12-31T13:30:00Z

Title: The oldest Zoophycos and implications for Early Cambrian deposit feeding Author: Sappenfield, Aaron; Droser, Mary L.; Kennedy, Martin John; McKenzie, Ryan Abstract: Zoophycos-group burrows are prevalent elements of the post-Cambrian trace fossil record. Here we report the oldest specimens of Zoophycos from Lower Cambrian strata of the Lower Member Wood Canyon Formation in southeastern California. In addition to these being the oldest examples of this well-known trace fossil, the discovery of these specimens also reveals the presence of deposit feeding considerably earlier than has been suggested for the advent of this feeding style. This type of activity may have had a significant impact on sediment mixing during the Precambrian–Cambrian transition, though the rarity and shallow tier position of these specimens suggests otherwise.

2011-12-31T13:30:00Z