WA
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1 map showing the Acreage Release Title W15-3 in the area of Overlapping Jurisdiction in the Perth Treaty. Requested by RET August 2014. LOSAMBA register 707
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Whether rift basins form as a consequence of pure shear or simple shear stretching of the lithosphere or a hybrid of these two end members has long been the focus of debate (McKenzie, 1978; Wernicke, 1985; Rosenbaum et al., 2008). It is generally accepted that under low strain pure shear dominates yet the debate rages with respect to highly extended continental margins. The key dataset to resolve this debate is the spatial distribution of syn-rift and post-rift basin subsidence resulting from mechanical thinning of the lithosphere and subsequent thermal re-thickening of the lithospheric mantle to its pre-rift thickness. An often-overlooked element of this debate is what lithospheric template is being stretched (Crosby et al., 2010). Most geodynamic models simply assume a standard lithospheric thickness of 100120 km, yet in the last decade teleseismic tomography has revealed that much of the Earth's continental land mass is underlain by lithosphere over double this thickness (Priestley and McKenzie, 2013). Here, we kinematically model the subsidence history of the Canning basin following Crosby et al. (2010). This intracratonic rift basin putatively overlies lithosphere 180 km thick, imaged using shear wave tomography (Kennett et al., 2013). The entire subsidence history of the, < 300 km wide and < 6 km thick, western Canning Basin is adequately explained by Ordovician rifting of pre-existing 100120 km thick lithosphere followed by post-rift thermal subsidence as described by the established pure shear model. In contrast, the < 150 km wide and 15 km thick Fitzroy Trough of the eastern Canning Basin reveals an almost continuous phase of normal faulting between Ordovician and Carboniferous Periods followed by negligible post-rift thermal subsidence. This pattern cannot be accounted for by a simple shear model (c.f. Drummond et al., 1991), as there is no record of excess post-rift subsidence in the basin, nor does the data fit the standard pure shear model. We attribute this difference in subsidence to a sharp change in mantle lithospheric thickness between the west and eastern Canning Basin. The presence of ~20 Ma diamond bearing lamproites intruded into the basin depocentre indicate that the present lithospheric thickness exceeds ~180 km (Evans et al., 2012). In order to account for the observed subsidence, at standard crustal densities, the lithospheric mantle is required to be depleted by 5070 kg m3. The actual depletion of the lowermost lithospheric mantle was assessed by modeling REE concentrations of the ~20 Ma lamproites along with other ultrapotassic rocks from the Kimberley, Yilgarn and Pilbara blocks following the method of Tainton and McKenzie (1994) which reveal a depletion of 4070 kg m3. This result suggests that thermal re-thickening of the lithospheric mantle did not occur following rifting, as it is unlikely that such a strongly depleted mantle source was available in the Phanerozoic to be frozen into the lowermost lithospheric mantle. Therefore, we conclude that thinning of thick lithosphere to thicknesses > 120 km is thermally stable and is not accompanied by post-rift thermal subsidence driven by thermal re-thickening of the lithospheric mantle. The discrepancy between estimates of lithospheric thickness derived from subsidence data in the Western Canning and that derived from shear wave tomography suggests that the latter technique cannot resolve lithospheric thickness variations on < 300 km half wavelengths.
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After CO2 is injected into the saline aquifer, the formation water inside the porous media becomes more acidic. This will significantly affect the original chemical equilibrium underground, and induce or speed up various processes of dissolution and precipitation depending on the reservoir pressure, temperature and salinity of formation water. The Early Cretaceous Gage Sandstone has been identified as a potential reservoir unit suitable for large-scale CO2 storage in the offshore southern Perth Basin. This study assesses the contribution of mineralisation trapping to CO2 storage capacity of the Gage Sandstone through a comprehensive geochemical modelling. Analyses of mineral assemblages in reservoir rocks and properties of formation water were used to assess dissolutions of unstable components under an acidic environment such as potassium-feldspar, plagioclase and carbonate, and the precipitation of calcite and kaolinite, which are considered to be the main water-rock interactions during the post-injection period. The chemical reaction was treated as a function of time. Three software packages were used to run the geochemical reaction simulation to ascertain the practical capabilities of predicting the effects of CO2 injection underground and the storage potential of the Gage Sandstone reservoir. Sensitivity analysis was carried out using different: 1) equations of state, 2) methods for solubility modelling, 3) models of activity coefficient estimation, 4) time scales, and 5) assemblages of minerals in the Gage Sandstone. This study analysed the effects of CO2 injection on reservoir porosity and permeability together with the geochemical modelling.
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Total magnetic intensity (TMI) data measures variations in the intensity of the Earth's magnetic field caused by the contrasting content of rock-forming minerals in the Earth crust. Magnetic anomalies can be either positive (field stronger than normal) or negative (field weaker) depending on the susceptibility of the rock. The data are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. These line dataset from the Leonora, WA, 1991/92 survey were acquired in 1992 by the WA Government, and consisted of 10225 line-kilometres of data at 400m line spacing and 60m terrain clearance. To constrain long wavelengths in the data, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of the survey data. This survey data is essentially levelled to AWAGS.
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The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium (K), uranium (U) and thorium (Th). The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This Leonora, WA, 1991/92 (P586), radiometric line data, AWAGS levelled were acquired in 1992 by the WA Government, and consisted of 10225 line-kilometres of data at 400m line spacing and 60m terrain clearance. To constrain long wavelengths in the data, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of the survey data. This survey data is essentially levelled to AWAGS.
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The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium (K), uranium (U) and thorium (Th). The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This Laverton, WA 1992 (P587), radiometric line data, AWAGS levelled were acquired in 1992 by the WA Government, and consisted of 10225 line-kilometres of data at 400m line spacing and 60m terrain clearance. To constrain long wavelengths in the data, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of the survey data. This survey data is essentially levelled to AWAGS.
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Total magnetic intensity (TMI) data measures variations in the intensity of the Earth's magnetic field caused by the contrasting content of rock-forming minerals in the Earth crust. Magnetic anomalies can be either positive (field stronger than normal) or negative (field weaker) depending on the susceptibility of the rock. The data are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. These line dataset from the Laverton, WA 1992 survey were acquired in 1992 by the WA Government, and consisted of 10225 line-kilometres of data at 400m line spacing and 60m terrain clearance. To constrain long wavelengths in the data, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of the survey data. This survey data is essentially levelled to AWAGS.
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Total magnetic intensity (TMI) data measures variations in the intensity of the Earth's magnetic field caused by the contrasting content of rock-forming minerals in the Earth crust. Magnetic anomalies can be either positive (field stronger than normal) or negative (field weaker) depending on the susceptibility of the rock. The data are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. These line dataset from the Medusa Banks, Port Keats, WA, 1994 survey were acquired in 1994 by the WA Government, and consisted of 68378 line-kilometres of data at 500m line spacing and 100m terrain clearance. To constrain long wavelengths in the data, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of the survey data. This survey data is essentially levelled to AWAGS.
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The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium (K), uranium (U) and thorium (Th). The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This Medusa Banks, Port Keats, WA, 1994 (P608), radiometric line data, AWAGS levelled were acquired in 1994 by the WA Government, and consisted of 68378 line-kilometres of data at 500m line spacing and 100m terrain clearance. To constrain long wavelengths in the data, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of the survey data. This survey data is essentially levelled to AWAGS.
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Total magnetic intensity (TMI) data measures variations in the intensity of the Earth's magnetic field caused by the contrasting content of rock-forming minerals in the Earth crust. Magnetic anomalies can be either positive (field stronger than normal) or negative (field weaker) depending on the susceptibility of the rock. The data are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. These line dataset from the Dixon Range - Gordon Downs, WA, 1991 survey were acquired in 1992 by the WA Government, and consisted of 43000 line-kilometres of data at 400m line spacing and 100m terrain clearance. To constrain long wavelengths in the data, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of the survey data. This survey data is essentially levelled to AWAGS.