DSpace Community:https://hdl.handle.net/2440/824222024-03-29T02:26:13Z2024-03-29T02:26:13ZThe Pamatta Pass Canyon Complex: Neoproterozoic Wonoka Formation, Flinders Ranges, South AustraliaHiggins, J.https://hdl.handle.net/2440/1404542024-03-20T03:01:24Z1997-01-01T00:00:00ZTitle: The Pamatta Pass Canyon Complex: Neoproterozoic Wonoka Formation, Flinders Ranges, South Australia
Author: Higgins, J.
Abstract: Deposition of the late Proterozoic Wilpena Group is characterised by numerous sequence boundaries or regional disconformities that reflect the tectono-stratigraphic history of the Adelaide Geosyncline. The most prominent of these are related to kilometre-sized incised valley systems within the lower Wonoka Formation. Alternative subaerial and submarine origins have been proposed. Recent work substantiates the subaerial model as it accounts for several lines of evidence the submarine model could not adequately answer.
The Wonoka Formation in the Pamatta Pass Canyon Complex was first observed by Binks (1971). Observations made during field mapping support a subaerial origin and record evidence for multiple phases of canyon incision.
A pre-Wonoka Formation phase of deformation (probably related to the Penguin Orogeny in northwest Tasmania, or the Beardmore Orogeny in Antarctica) is interpreted to have existed. Syn-depositional tectonism is likewise attributed to this event. Compressional deformation during the Delamerian Orogeny subsequently deformed the entire sedimentary prism in a complex array of NNE/SSW folds.
Description: This item is only available electronically.1997-01-01T00:00:00ZForcing factors influencing deposition of the Wonoka Formation, Flinders Ranges, South Australia, and triggers for canyon development.Dixon, Jameshttps://hdl.handle.net/2440/1404492024-03-18T06:55:55Z1999-01-01T00:00:00ZTitle: Forcing factors influencing deposition of the Wonoka Formation, Flinders Ranges, South Australia, and triggers for canyon development.
Author: Dixon, James
Abstract: The latest Neoproterozoic Wilpena Group of the Flinders Ranges, South Australia, has been the subject of many studies, particularly concerning the Wonoka Formation, as the origin of canyons that cut down from this formation into lower formations has puzzled workers for decades. Two models for the ancient Wonoka canyons have been proposed by various authors, the subaerial model, and the submarine model. A tectonic mechanism with regional uplift resulting in a fall of sea-level has been proposed for the subaerial model with previously little evidence to support this in areas away from canyon incision.
This study uses measured stratigraphic sections to show deepening and then shallowing of sea-level for older parts of the Wonoka Formation away from areas of canyon incision. Studied evidence includes the appearance and disappearance of turbidite beds, slumping within unit 2 and the formation of an irregular erosional surface associated with minor brecciolas low in unit 3. The down-cut surface is presumed to represent a significant sequence boundary coeval with known deep erosional canyons to the south and in the northern Flinders Ranges. Stable carbon isotope work was carried out and the results indicate that a stratified sea is possible for lower Wonoka time, coinciding with canyon incision and down-draw or fall of sea-level.
The data collected is consistent with a tectonic event that caused the relative fall of sea-level by regional uplift and prompted canyon incision low in unit three of the Wonoka Formation. Several models for fall of sea-level including lowering due to glaciation (land-ice), salt diapirism, tectonic influences and a Messinian-style down-draw are considered.
Description: This item is only available electronically.1999-01-01T00:00:00ZEarly Palaeozoic mafic magmatism associated with intracontinental rifting in the Harts Range, Central AustraliaLawley, C. G.https://hdl.handle.net/2440/1402592023-12-20T02:03:35Z2005-01-01T00:00:00ZTitle: Early Palaeozoic mafic magmatism associated with intracontinental rifting in the Harts Range, Central Australia
Author: Lawley, C. G.
Abstract: Mafic sills intrude the Upper Stanovos Gneiss in the southeastem Arunta Inlier, central Australia referred to here as the Stanovos Igneous Suite (SIS). The host rock Upper Stanovos Gneiss was deposited in a localised depo-centre within the Amadeus Basin at 545Ma from sediments derived from the Musgrave Block. The SIS intruded the Upper Stanovos Gneiss in a deep (approximately 16km) localised strikeslip basin (the Irindina sub-basin) formed during intracratonic rifting. LA-ICPMS U/Pb zircon dating of granites associated with the mafic rocks gives 524Ma ± 8Ma. The intrusions occurred at 5.3 kbars at temperatures > 1150°C. The mafic sills are extensively boudinaged due to the extensional Larapinta Event that occurred during the early Ordovician 480-460Ma. The event metamorphosed the Irindina sub-basin sediments and mafic volcanics to amphibolite and granulite grade.
The extent of rifting was insufficient to have enabled partial melting of the lithosphere to occur via passive rifting. This combined with coeval widespread occurrences of mafic magmatism throughout Australia, including the continental flood basalts with the same characteristic low Ba/Rb, Nb/Th and TiN geochemical features as the SIS, indicate the presence of a mantle plume beneath the continent during the mid to late Cambrian. The SIS has tholeiitic affinities and a N-MORB like mantle signature altered by fractional crystallisation and crustal assimilation. Two component mixing isotopic ratios indicate that the mafic rocks have a crustal influence and the granites have a mantle input. Geochemistry and isotopic signatures of the mafic rocks provide insights into the evolution of the mantle reservoir beneath a newly recognised early Palaeozoic intracratonic rift in central Australia.
Description: This item is only available electronically.2005-01-01T00:00:00ZIron mobility in shallow hydrothermal systems: insights from hematite-quartz veins and breccias from ArkaroolaBirch, F.https://hdl.handle.net/2440/1400272023-12-01T01:01:37Z2021-01-01T00:00:00ZTitle: Iron mobility in shallow hydrothermal systems: insights from hematite-quartz veins and breccias from Arkaroola
Author: Birch, F.
Abstract: A series of hydrothermal hematite and quartz veins are found within the Adelaidean cover sequence at Petalinka Waterfall and Mt Oliphant as well as within the Mt Painter Inlier in the Radium Ridge Breccia and Mt Gee Sinter. Past studies have described a genetic relationship between the Radium Ridge Breccia and Mt Gee Sinter formations. Mineral geochemistry and U-Pb monazite and hematite dating have supported this claim as well as expanded the hydrothermal history of the local area. Monazite formation at ca 360 Ma across the two locations suggests early generations of hematite at Mt Gee predate this age, with a resetting of hematite occurring around ca 300 Ma. The Mt Gee Sinter has been seen to crosscut Cretaceous tillite, giving a maximum age of this generation of hydrothermal activity of ca 220 Ma. Hematite mineral geochemistry also genetically links the hematite and quartz veins found at Petalinka Waterfall and Mt Oliphant. These veins also see multiple generations of vein formation, initiating with the Delamarian Orogeny, evident from monazite dating from Petalinka Waterfall at ca 493 Ma coupled with textural evidence from Mt Oliphant. Second generation veining has been dated using U-Pb dating of hematite, giving an age of ca 350 Ma. This suggests the geothermal conditions at ca 360-350 Ma were regional with Petalinka Waterfall hematite dates correlating with Mt Painter Inlier monazite dates. Oxygen isotope analysis of quartz and hematite suggest metamorphic sourced hydrothermal fluid at temperatures of 450oC at the Mt Painter Inlier and Petalinka Waterfall and 600oC at Mt Oliphant. This hydrothermal fluid was likely very saline, similar to the hydrothermal veins discussed by Bakker and Elburg (2006).
Description: This item is only available electronically.2021-01-01T00:00:00Z