Multi-scale integrated structural and aeromagnetic analysis to guide tectonic models: An example from the eastern Musgrave Province, Central Australia

In many polydeformed Precambrian provinces, the understanding of their tectonic history is limited insufficient exposure, which leads to difficulty in developing links between local and regional architecture and results in poorly constrained models of their regional-scale architecture. High-resolution aeromagnet data allows interpretation and modelling at a scale comparable to structural mapping, and by integrati these methods. these links can be developed with high confidence. As an example, we integrate structure mapping, aeromagnetic data interpretation and 3D magnetic inversions in a multi-scale structural analysis the polydeformed eastern Musgrave Province in central Australia. Deformation during the ca. 1200 P Musgravian Orogeny is characterised by an originally northeast-trending structural grain defined by shear zones and tight to isoclinal folds at all scales. 3D magnetic inversion models of syn-to-post Musgravity granites indicate that this structural grain is predominantly west dipping. This architecture suggests that northeast-oriented fold and thrust belt developed as a result of northwest-southeast compression in cent Australia during the Musgravian Orogeny. The next deformation event is characterised by an array originally east-southeast trending shear zones that truncate and offset the Musgravian structural grain with. apparent dextral displacements of up to 1 km. These shear zones are commonly co-located with mafic a granitic dykes, suggesting a dilational origin, and they are interpreted to have initiated under northeast southwest extension during the ca. 1080 Ma Giles Event. The architecture of these two Mesoproterozoic( events was later extensively overprinted by two deformation events during the Pan-African aged (, 550 Ma) Petermann Orogeny. The first is characterised by the widespread reactivation of Mesoproterozoic structures, resulting in a network of shear zones of variable orientation, and the second is characterised the development of crustal-scale transpressional shear zones, motion on which has caused the rotation lithospheric blocks and the reorientation of prior structural trends by up to 90 degrees. Collectively, the architecture of these two events suggests broadly north-south crustal shortening in central Australia as an intraplacental response to Gondwana assembly. This example demonstrates that the integration of structural geology with aeromagnetic interpretation and modelling can be used to develop high-confidence links between local a. regional structures. These links permit the derivation of better constrained models of major tectonic even particularly in regions where outcrop is poor and the structural architecture is complex. (C) 2009 Elsevier B.V. All rights reserved.