HR: 0800h
AN: T51D-0755    [Abstracts]
TI: Intraplate deformation on north-dipping basement structures in the Northern Gawler Craton, Australia: reactivation of original terrane boundaries or later intra-cratonic thrusts?
AU: * Baines, G
EM: graham.baines@adelaide.edu.au
AF: Centre for Mineral Exploration Under Cover, School of Earth and Environmental Sciences University of Adelaide, Adelaide, SA 5005, Australia
AU: Giles, D
EM: david.giles@adelaide.edu.au
AF: Centre for Mineral Exploration Under Cover, School of Earth and Environmental Sciences University of Adelaide, Adelaide, SA 5005, Australia
AU: Betts, P G
EM: Peter.Betts@sci.monash.edu.au
AF: School of Geosciences, Australian Crustal Research Centre, Monash University, Melbourne, VIC 3800, Australia
AU: Backé, G
EM: guillaume.backe@adelaide.edu.au
AF: Centre for Mineral Exploration Under Cover, School of Earth and Environmental Sciences University of Adelaide, Adelaide, SA 5005, Australia
AB: Multiple intraplate orogenic events have deformed Neoproterozoic to Carboniferous sedimentary sequences that cover the Archean to Mesoproterozoic basement of the northern Gawler Craton, Australia. These intraplate orogenies reactivated north-dipping basement penetrating faults that are imaged on seismic reflection profiles. These north-dipping structures pre-date Neoproterozoic deposition but their relationships to significant linear magnetic and gravity anomalies that delineate unexposed Archean to Early Mesoproterozoic basement terranes are unclear. The north-dipping structures are either terrane boundaries that formed during continental amalgamation or later faults, which formed during a mid- to late-Mesoproterozoic transpressional orogeny and cross-cut the original lithological terrane boundaries. We model magnetic and gravity data to determine the 3D structure of the unexposed basement of the northern Gawler Craton. These models are constrained by drill hole and surface observations, seismic reflection profiles and petrophysical data, such that geologically reasonable models that can satisfy the data are limited. The basement structures revealed by this modelling approach constrain the origin and significance of the north-dipping structures that were active during the later intraplate Petermann, Delamerian and Alice Springs Orogenies. These results have bearing on which structures are likely to be active during present-day intraplate deformation in other areas, including, for example, current seismic activity along similar basement structures in the Adelaide "Geosyncline".
DE: 1219 Gravity anomalies and Earth structure (0920, 7205, 7240)
DE: 1517 Magnetic anomalies: modeling and interpretation
DE: 8103 Continental cratons
DE: 8107 Continental neotectonics (8002)
DE: 8110 Continental tectonics: general (0905)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting