GEOSCIENCE AUSTRALIA Inter-reefal Seabed Sediments and Geomorphology of the Great Barrier Reef, a Spatial Analysis Emma Mathews, Andrew Heap & Murray Woods Record 2007/09 SPATIAL INFORMATION FOR THE NATION Geoscience Australia Record 2007/09 Inter-reefal seabed sediments and geomorphology of the Great Barrier Reef, a spatial analysis Emma Mathews, Andrew Heap and Murray Woods Marine Coastal and Environment Group, Petroleum and Marine Division, Geoscience Australia, GPO Box 378, Canberra, Australia Inter-reefal seabed sediments and geomorphology of the Great Barrier Reef, a spatial analysis GEOSCIENCE AUSTRALIA Chief Executive Officer: Dr Neil Williams Department of Industry, Tourism & Resources Minister for Industry, Tourism & Resources: Senator The Hon. Ian Macfarlane, MP Parliamentary Secretary: The Hon. Bob Baldwin, MP Secretary: Mark Paterson © Commonwealth of Australia 2007 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. ISSN: 1448-2177 ISBN: 978 1 921236 36 5 (Hardcopy & CD-ROM) ISBN: 978 1 921236 42 6 (Web) GeoCat No.64758 Bibliographic reference: Mathews, E.J., Heap, A.D., and Woods, M. (2007). Inter-reefal seabed sediments and geomorphology of the Great Barrier Reef, a spatial analysis. Geoscience Australia, Record 2007/09, 140pp. Correspondence for feedback: Andrew Heap Geoscience Australia GPO Box 378 Canberra ACT 2601 [email protected] 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 rely solely on this information when making a commercial decision. ii Contents List of Figures.................................................................................................................................. v List of Tables............................................................................................................................... viii Executive Summary........................................................................................................................ x Acknowledgements .....................................................................................................................xii 1. Introduction................................................................................................................................. 1 1.1. BACKGROUND ................................................................................................................... 1 1.2. REGIONAL SETTING ......................................................................................................... 1 1.3. MARINE PARK ZONING AND MANAGEMENT ........................................................ 5 1.3.1. Management................................................................................................................. 5 1.3.2. Seabed characterisation and monitoring.................................................................. 7 1.4. REPORT AIMS AND STRUCTURE .................................................................................. 8 2. Previous Work............................................................................................................................. 9 2.1 GEOLOGICAL SETTING..................................................................................................... 9 2.1.1 Tectonics ........................................................................................................................ 9 2.1.2. Late Quaternary History .......................................................................................... 11 2.2. REGIONAL GEOMORPHOLOGY.................................................................................. 14 2.3. OCEANOGRAPHY............................................................................................................ 23 2.3.1. Water Circulation ...................................................................................................... 23 2.3.2. Sediment Transport................................................................................................... 25 2.4. REGIONAL SEDIMENTOLOGY..................................................................................... 30 2.4.1. Sediment Facies.......................................................................................................... 31 2.4.2. Sediment Texture and Composition ....................................................................... 33 3. Methods...................................................................................................................................... 41 3.1. SAMPLE ACQUISITION .................................................................................................. 41 3.2. SAMPLE PROCESSING AND ANALYSIS ................................................................... 43 3.2.1. Sediment texture........................................................................................................ 43 3.2.2. Sediment composition .............................................................................................. 44 3.3. DATA PROCESSING AND ANALYSIS......................................................................... 45 3.3.1. Sample station locations ........................................................................................... 45 3.3.2. Sediment Attribute Data........................................................................................... 46 3.3.3. Geomorphic Features Data....................................................................................... 49 4. Inter-reefal sedimentology ..................................................................................................... 51 4.1. SURFACE SEDIMENTS .................................................................................................... 51 iii Inter-reefal seabed sediments and geomorphology of the Great Barrier Reef, a spatial analysis 4.1.1. Marine Park ................................................................................................................ 51 4.1.2. Inner Shelf (0-20 m) ................................................................................................... 54 4.1.3. Middle Shelf (20-40 m).............................................................................................. 61 4.1.4. Outer Shelf (40-90 m) ................................................................................................ 64 4.1.5. Continental Slope (90-~4000 m) ............................................................................... 67 5. Application to the Marine Park Authority planning zones ............................................. 71 5.1. PHYSICAL CHARACTER OF THE PLANNING ZONES........................................... 71 5.1.1. Scientific Research Zone (SRZ) ................................................................................ 71 5.1.2. Preservation zone (PZ).............................................................................................. 73 5.1.3. Conservation Park Zone (CRZ) ............................................................................... 74 5.1.4. Buffer Zone (BZ) ........................................................................................................ 75 5.1.5. General Use Zone (GUZ).......................................................................................... 75 5.1.6. Habitat Protection (HPZ) and Marine National Park Zones (MNPZ) ............... 76 6. Discussion.................................................................................................................................. 79 6.1. REGIONAL SEDIMENT FACIES .................................................................................... 79 6.1.1 Occurrence and distribution ..................................................................................... 79 6.1.2. Sediment sources and supply .................................................................................. 81 6.1.3. Comparison with existing facies models of GBR shelf......................................... 84 6.2. SEABED ENVIRONMENTS AND HABITATS ............................................................. 84 6.2.1. Implications for Marine Park management ........................................................... 85 7. References.................................................................................................................................. 87 8. Appendices ................................................................................................................................ 97 8.1. Appendix A - Sediment grain size and composition maps .................................... 97 8.2. Appendix B - Folk classification statistics ............................................................... 122 8.3. Appendix C - Laser grain size results...................................................................... 122 8.4. Appendix D – Sieve grain size and carbonate results ........................................... 122 8.5. Appendix E - Sediment statistics of the seabed...................................................... 122 8.6. Appendix