The shape, scale and distribution of irregular zones of fragmental rocks within the overal chaotic deposits of the lower 300m of the Mawson Formation at Coombs Hills was determined. The chaotic deposits are thought to represent an unusually large composite volcanic conduit, in which subterranean jets of debris constitute an important transport mechanism. Geological mapping at scales varying from ... 1:20,000 to 1:1,000 was completed using aerial photographs, handheld GPS and laser ranging survey equipment. Extensive data on the size shape and location of the fragmented zones was collected. The mixed rocks within different zones were quantitatively characterised by gridded outcrop clast counting. The relationship among zones and surrounding rock was described. The range of contact relationships among contacts between different rock zones within the vent cojmplex, in terms of sharpness, angularity or curvature and scales of irregularity was established. Four subtypes of structureless tuff breccia and lapilli tuff were distunguished. These zones and accompanying clastic dikes, Beacon rafts, pyroclastic raftes, clastic dikes and basalt intrusions were systematically described, catalogued, photographed and sampled. General and thematic maps were prepared for interpretation of volcanic processes. Around 140 samples were collected from the bedrock and analysed by thin section and geochemical purposes. From the thin sections, quantitative clast-shape and vesicle population data, including vesicle volume and interconnectedness, was determined by image analysis on SEM-generated photographs.
Any remaining geological samples are lodged in the geology department, University of Otago. All data is in the MSc thesis. Some photographs and field notebooks may reside with the investigator.
Ross, P.-S. Volcanology of the Mawson Formation at Coombs and Allan Hills, South Victoria Land, Antarctica.Ph.D., University of Otago : . 2005.
Ross, P.-S. White, J.D.L. Discontinuous volcanic eruptions in a phreatomagmatic vent complex: Coombs Hills, South Victoria Land. Canadian Antarctic research network newsletter 16: 4-6, 2003.
Ross, P.-S. Ukstins Peate, I. ... McClintock, M.K. Xu, Y.G. Skilling, I.P. White, J.D.L. Houghton, B.F. Mafic volcaniclastic deposits in flood basalt provinces: A review. Journal of volcanology and geothermal research 145: 281-314, 2005.
Ross, P.-S. White, J.D.L. Unusually large clastic dykes formed by elutriation of a poorly sorted, coarser-grained source. Journal of the Geological Society of London 162: 579-582, 2005.
Ross, P.-S. White, J.D.L. Debris jets in continental phreatomagmatic volcanoes: A field study of their subterranean deposits in the Coombs Hills vent complex, Antarctica. Journal of volcanology and geothermal research 149(1-2): 62-84, 2006.
Ross, P.-S. White, J.D.L. Mafic, large-volume, pyroclastic density current deposits from phreatomagmatic eruptions in the Ferrar large igneous province. Journal of geology 113: 627-649, 2005.
Ross, P.S., White, J.D.L., Zimanowski, B. And Buettner, R. 2008 online). Multiphase flow above explosion sites in dbris-filled volcanic vents: insights from analogue experiments. In: Dynamics of Volcanic Explosions: Field Observations, Experimental Constraints and Integrated Modelling. Nishimura, T., Melnik, O. and Valentine, G. (eds.) Journal of Volcanology and Geothermal Research.