Geomorphology and Sedimentology of the South Western Planning Area of Australia
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GEOSCIENCE AUSTRALIA Geomorphology and Sedimentology of the South Western Planning Area of Australia Review and synthesis of relevant literature in support of Regional Marine Planning Laura Richardson, Emma Mathews & Andrew Heap Record 2005/17 SPA TIAL INFORMATION FOR THE NA TION Geoscience Australia Record 2005/17 Geomorphology and Sedimentology of the South Western Planning Area of Australia Review and synthesis of relevant literature in support of Regional Marine Planning Laura Richardson, Emma Mathews and Andrew Heap Geoscience Australia, GPO Box 378, Canberra, ACT 2601, Australia Geomorphology and Sedimentology of the SWPA of Australia Department of Industry, Tourism & Resources Minister for Industry, Tourism & Resources: The Hon. Ian Macfarlane, MP Parliamentary Secretary: The Hon. Warren Entsch, MP Secretary: Mark Paterson Geoscience Australia Chief Executive Officer: Dr Neil Williams © Commonwealth of Australia, 2005 This work is copyright. Apart from any fair dealings for the purpose of study, research, criticism, or review, as permitted under the Copyright Act 1968, no part may be reproduced by any process without written permission. Copyright is the responsibility of the Chief Executive Officer, Geoscience Australia. Requests and enquiries should be directed to the Chief Executive Officer, Geoscience Australia, GPO Box 378 Canberra ACT 2601. Geoscience Australia has tried to make the information in this product as accurate as possible. However, it does not guarantee that the information is totally accurate or complete. Therefore, you should not solely rely on this information when making a commercial decision. ISSN: 1448-2177 ISBN: 1 920871 56 X GeoCat No. 63721 Bibliographic reference: Richardson, L., Mathews, E. and Heap, A. (2005). Geomorphology and Sedimentology of the South Western Planning Area of Australia: review and synthesis of relevant literature in support of Regional Marine Planning. Geoscience Australia, Record 2005/17. 124pp. Correspondence for feedback: Andrew Heap Geoscience Australia GPO Box 378 Canberra ACT 2601 [email protected] ii Contents List of Figures.................................................................................................................. v List of Tables ..................................................................................................................vi Acknowledgements .......................................................................................................vii Executive Summary........................................................................................................ x 1. Introduction.................................................................................................................1 1.1. Background........................................................................................................ 1 1.1.1. Oceans Policy and Regional Marine Planning ..................................... 1 1.1.2. Scope and Relevance ............................................................................. 1 1.2. South Western Planning Area............................................................................ 3 1.2.1. Rottnest .................................................................................................. 5 1.2.2. South West.............................................................................................. 8 1.2.3. Great Australian Bight......................................................................... 10 1.2.4. Spencer and St. Vincent Gulfs.............................................................. 10 2. Rottnest...................................................................................................................... 11 2.1. Tectonic Setting ............................................................................................... 12 2.2. Geomorphology ............................................................................................... 14 2.3. Oceanography .................................................................................................. 21 2.4. Surface Sediments............................................................................................ 26 2.5. Late Quaternary Evolution............................................................................... 33 3. South West................................................................................................................. 38 3.1. Tectonic Setting ............................................................................................... 38 3.2. Geomorphology ............................................................................................... 40 3.3. Oceanography .................................................................................................. 44 3.4. Surface Sediments............................................................................................ 47 3.5. Late Quaternary Evolution............................................................................... 51 4. Great Australian Bight............................................................................................. 53 4.1. Tectonic Setting ............................................................................................... 53 4.2. Geomorphology ............................................................................................... 56 4.3. Oceanography .................................................................................................. 60 4.4. Surface Sediments............................................................................................ 64 4.5. Acoustic Facies................................................................................................ 68 4.6. Late Quaternary Evolution............................................................................... 72 5. Spencer and St. Vincent Gulfs................................................................................. 74 5.1. Tectonic Setting ............................................................................................... 75 5.2. Geomorphology ............................................................................................... 76 5.3. Oceanography .................................................................................................. 79 5.4. Surface Sediments............................................................................................ 84 5.5. Acoustic Facies................................................................................................ 90 5.6. Late Quaternary Evolution............................................................................... 91 iii Geomorphology and Sedimentology of the SWPA of Australia 6. Implications for Regional Marine Planning ...........................................................94 6.1. Habitat Mapping...................................................................................................94 6.2. Sediment and Biota Relationships......................................................................101 6.3. Summary ............................................................................................................104 7. References ................................................................................................................106 8. Appendix A: Classification of Acoustic Facies .....................................................122 iv List of Figures Figure 1.1. Map of South Western Planning Area............................................................ 2 Figure 1.2. False-colour bathymetric image of southwestern Australian margin............. 3 Figure 1.3. False-colour image showing features cited in the text ................................... 4 Figure 1.4. Map showing major geomorphic features of the region................................. 6 Figure 1.5. Physical oceanography of the southwestern Australian margin..................... 7 Figure 1.6. Map showing locations of samples held in MARS ........................................ 8 Figure 1.7. Map showing samples with quantitative grain size held in MARS. .............. 9 Figure 1.8. Map showing samples with quantitative CaCO3 content held in MARS....... 9 Figure 2.1. False-colour bathymetric image of the Rottnest Shelf ................................. 12 Figure 2.2. Map showing the geological setting of the Rottnest .................................... 13 Figure 2.3. Schematic diagram of southern Rottnest Shelf morphology........................ 15 Figure 2.4. Schematic cross-section of the northern Rottnest Shelf............................... 16 Figure 2.5. False-colour bathymetric image of the Houtman Abrolhos Islands............. 18 Figure 2.6. Bathymetry map of the Houtman Abrolhos platform groups....................... 19 Figure 2.7. Schematic cross-section of the Easter Platform ........................................... 19 Figure 2.8. Idealised morphology of the inner Abrolhos Shelf ...................................... 20 Figure 2.9. False-colour bathymetric image of the Perth Canyon .................................. 20 Figure 2.10. Satellite image of the Leeuwin Current...................................................... 23 Figure 2.11. Map showing interpreted saline outflow from Shark Bay ......................... 24 Figure 2.12. Map showing the distribution of significant wave height .......................... 25 Figure 2.13. Map showing the distribution of wave energy ........................................... 26 Figure 2.14.