FS Sonne Fahrtbericht / Cruise Report SO193 MANIHIKI Temporal, Spatial, and Tectonic Evolution of Oceanic Plateaus Suva/Fiji – Apia/Samoa 19.05. - 30.06.2007 IFM-GEOMAR REPORT Berichte aus dem Leibniz-Institut für Meereswissenschaften an der Christian-Albrechts-Universität zu Kiel Nr. 13 September 2007 FS Sonne Fahrtbericht / Cruise Report SO193 MANIHIKI Temporal, Spatial, and Tectonic Evolution of Oceanic Plateaus Suva/Fiji – Apia/Samoa 19.05. - 30.06.2007 Berichte aus dem Leibniz-Institut für Meereswissenschaften an der Christian-Albrechts-Universität zu Kiel Nr. 13, September 2007 ISSN Nr.: 1614-6298 Das Leibniz-Institut für Meereswissenschaften The Leibniz-Institute of Marine Sciences is a ist ein Institut der Wissenschaftsgemeinschaft member of the Leibniz Association Gottfried Wilhelm Leibniz (WGL) (Wissenschaftsgemeinschaft Gottfried Wilhelm Leibniz). Herausgeber / Editor: Reinhard Werner and Folkmar Hauff IFM-GEOMAR Report ISSN Nr.: 1614-6298 Leibniz-Institut für Meereswissenschaften / Leibniz Institute of Marine Sciences IFM-GEOMAR Dienstgebäude Westufer / West Shore Building Düsternbrooker Weg 20 D-24105 Kiel Germany Leibniz-Institut für Meereswissenschaften / Leibniz Institute of Marine Sciences IFM-GEOMAR Dienstgebäude Ostufer / East Shore Building Wischhofstr. 1-3 D-24148 Kiel Germany Tel.: ++49 431 600-0 Fax: ++49 431 600-2805 www.ifm-geomar.de 1 CONTENTS Page Summary..........................................................................................................................................................2 Zusammenfassung..........................................................................................................................................3 1. Acknowledgements .....................................................................................................................................4 2. Participants..................................................................................................................................................5 2.1. Ship´s Crew ...................................................................................................................................5 2.2. Principal Investigators for MANIHIKI ............................................................................................5 2.3 Scientific Co-operators...................................................................................................................5 2.4 Scientific Party of SO 193 Cruise ..................................................................................................5 2.5. Institutions......................................................................................................................................6 3.Background and Major Objectives of SO193 MANIHIKI............................................................................7 3.1. Large Igneous Provinces ..............................................................................................................7 3.2. The Manihiki Plateau and the Large Plateaus in the SW-Pacific................................................9 3.3. Objectives of the MANIHIKI Project............................................................................................12 4. Cruise Narrative .......................................................................................................................................14 5. Bathymetry and Rock Sampling ...............................................................................................................19 5.1. Methods .......................................................................................................................................19 5.1.1. Bathymetry.....................................................................................................................19 5.1.2. Rock sampling ...............................................................................................................20 5.2. Sampling Report and Preliminary Results .................................................................................21 5.2.1. Western Plateaus ..........................................................................................................21 5.2.2. The Large Interior Fault Systems: Suvorov Trough and Danger Islands Troughs...............................................................................................26 5.2.3. North Plateau and Adjacent Areas. ..............................................................................32 5.2.4. Northeastern Margin and Adjacent Features ...............................................................36 5.2.5. High Plateau ..................................................................................................................40 5.2.6. Manihiki Scarp ...............................................................................................................44 5.2.7. Southern “Apophysis” of the High Plateau ...................................................................51 5.2.8. Samoan Basin Seamounts............................................................................................53 5.2.9. Bathymetry and Hard Rock Sampling Summary .........................................................55 5.3. Volcaniclastic Rocks (C.I. Schipper) ..........................................................................................57 6. Tectonics (M.F. Coffin)..............................................................................................................................62 6.1. Background..................................................................................................................................62 6.2. Formation of the Manihiki Plateau..............................................................................................65 6.2.1. Tectonic Framework......................................................................................................65 6.2.2. Geodynamic Models......................................................................................................67 6.3. Post-emplacement Tectonism of the Manihiki Plateau..............................................................68 6.3.1. Danger Islands Troughs................................................................................................69 6.3.2. High-North Basin ...........................................................................................................72 6.3.3. Linear Ridges.................................................................................................................72 6.3.4. Suvorov Trough .............................................................................................................74 6.3.5. East Manihiki Scarp.......................................................................................................75 6.3.6. Seamounts.....................................................................................................................75 7. Biology (C. Lüter, B. Neuhaus, J. Kasper, E. Ullrich) ..............................................................................77 7.1. Methods .......................................................................................................................................77 7.1.1. Shipboard Collecting Procedures .................................................................................77 7.1.2. Meiofauna ......................................................................................................................77 7.1.3. Macrofauna....................................................................................................................78 7.2. Preliminary Results and Discussion ...........................................................................................78 7.2.1. General Observations and Collecting Report...............................................................78 7.2.2. Meiofauna ......................................................................................................................79 7.2.3. Macrofauna....................................................................................................................80 7.2.4. TV-Observation of the Sea Floor..................................................................................80 8. References ................................................................................................................................................82 Appendices: I. Sampling Summary II. Rock Description III. Biological Sampling IV. Overview Map I (locations of the map sections presented in chapter 5) V. Overview Map II (SO193 sampling sites) 2 SUMMARY The research project SO193 MANIHIKI comprises investigations of volcanic and tectonic structures, magmatic rocks and marine organisms at the submarine Manihiki Plateau in the SW-Pacific. The Manihiki Plateau largely consists of volcanic rocks and represents a Mid- Cretaceous flood basalt or Large Igneous Province (LIP). The geological studies carried out on R/V SONNE cruise SO193 focused on bathymetric mapping of key areas in the Manihiki Plateau region, and representative hard rock sampling of all major geomorphological units of the plateau as well as seamounts on the adjacent oceanic crust, and the major fault systems crosscutting the plateau. SO193 MANIHIKI aims to reconstruct the origin and spatial and temporal evolution of the Manihiki Plateau and to characterize the relationship between the Manihiki Plateau and other LIPs in the