The winners of the 2009 Midland Valley Student Structure Prize:

Read interviews with the winners by clicking on their names.

Undergraduate First Place: Emily Holcroft, James Cook University.

Abstract:  This report outlines the structure, geological units and the geological history of the Snake Creek area. Snake Creek is located close to Cloncurry, it is part of the Mt Isa Inlier and the formations that make up the area are from the Soldiers Cap Group. These formations are the Mt Norna formation, the Llewellyn Creek formation and the Corella formation. All the work that is presented in this report was completed in the field and is hand-drafted. The geological units that were found in the area were calc-silicate breccias, meta-sediments, turbidites and igneous intrusions. There were two distinct structural domains; Llewellyn Creek and Mt Norna, and the Corella domain. The area has undergone large scale folding and moderate to high grade metamorphism.

Undergraduate Second Place: Gabriel Goyannes, University of Buenos Aires

Abstract: Along the upper valley of Santa Cruz river, East of Argentino Lake, glacial lake, fluvioglacial and moraine deposits outcrop, in the nearby cliff along the current channel of the Santa Cruz River. These outcrops show deformations that have been analysed in the context of the tectonic evolution of the Southern Patagonia-Andean region and of the imprint that was left by the glacial episodes, extensively developed in the region. The glaciotectonic deformations considered here are independent of the regional tectonic structure and they are mostly localized and bounded in stratigraphic terms. The style of deformation also allows it to be separated from regional episodes of Quaternary tectonic activity and relates it instead to local causes, associated with the effect produced by the glacial advance on previous glacigenic deposits.

Postgraduate First Place: Richard Walker, Durham University

Onshore evidence for progressive changes in rifting directions during continental break-up in the NE Atlantic and the role of NW-SE trendingstructures in the Faroe-Shetland Basin

Abstract: The White Pointer and Hammerhead Delta—Deepwater Fold-Thrust Belts (DDWFTBs) are located in the Ceduna Sub-basin of the Bight Basin, offshore southern Australia. These DDWFTB systems are structurally independent deltaic wedges of late Albian-Santonian and late Santonian-Maastrichtian age, which detach above marine mudstones and shales of the Blue Whale and Tiger supersequences, respectively. The DDWFTBs are represented in the west and east by two delta lobes that are constrained by the position of their deepwater fold-thrust belts. Geometry of the structures in the DDWFTBs are dependent on the interaction of numerous variables including sediment input, amount of progradation, shape and depth of the detachment, thickness and lithology of the detachment substrate, overpressure development and presence of basement structures. Geometric differences between the two DDWFTBs, particularly the two deepwater fold-thrust belts results in different styles of deformation and different potential hydrocarbon trap geometries. The White Pointer DDWFTB contains up to three levels of detachment, while the Hammerhead DDWFTB changes from one level of detachment in the west to two in the east. Both DDWFTBs are composed of an extensional, transitional and compressional province whereby the extensional province is consistent with the delta top and the compressional province with the deepwater fold-thrust belt. The extensional provinces are characterized by regional listric, normal, growth faults, and rarely, counter-regional faults. The transitional provinces are composed of large-scale (< 15 km wavelength) detachment folds, minor thrust faults and chaotic folding of deltaic sediments where imaged. The compressional provinces are defined by imbricate thrust faults and associated folds of various geometries, spacing and scale. All structures in the DDWFTBs sole out or are rooted at or above the level of the basal detachment; thus, deformation is constrained to within the deltaic wedge.  Analysis of gravity-driven structures with respect to the in-situ stress field for the Bight Basin indicate low to moderate reactivation potential for deepwater fold-thrust belt structures in the compressional province, while listric, normal, growth faults in the extensional provinces of the DDWFTBs are at high risk of reactivation.