RV SONNE Fahrtbericht / Cruise Report SO 199 CHRISP Christmas Island Seamount Province and the Investigator Ridge: Age and Causes of Intraplate Volcanism and Geodynamic Evolution of the south-eastern Indian Ocean Merak/Indonesia - Singapore 02.08.2008 - 22.09.2008 99 CHR 1 ISP SO I 8 n S 0 v in 0 e g 2 s a . t i p 8 g o 0 a . istmas r t hr Isla C n e o d 2 0 r 2 2 a . v R 0 a e 9 i S inc J ea ov d mount Pr . / g 2 k e 0 a 0 r 8 e M IF R M-GEOMA IFM-GEOMAR REPORT Berichte aus dem Leibniz-Institut für Meereswissenschaften an der Christian-Albrechts-Universität zu Kiel Nr. 25 Januar 2009 RV SONNE Fahrtbericht / Cruise Report SO 199 CHRISP Christmas Island Seamount Province and the Investigator Ridge: Age and Causes of Intraplate Volcanism and Geodynamic Evolution of the south-eastern Indian Ocean Merak/Indonesia - Singapore 02.08.2008 - 22.09.2008 99 CHR 1 ISP SO I 8 n S 0 v in 0 e g 2 s . a t 8 i p g 0 o . a stmas i r t Chr Islan 2 o d e 0 r 2 a 2 v . R 0 a e i Se inc 9 J a ov d mount Pr / . g 2 k e 0 a 0 r 8 e M IF R M-GEOMA Berichte aus dem Leibniz-Institut für Meereswissenschaften an der Christian-Albrechts-Universität zu Kiel Nr. 25, Januar 2009 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, Folkmar Hauff and Kaj Hoernle 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 CHRISP...............................................................................................5 2.3 Scientific Co-operators...................................................................................................................5 2.4 Scientific Party of SO199 Cruise ...................................................................................................5 2.5. Institutions......................................................................................................................................6 3. Major Objectives and Background of SO199 CHRISP (R. Werner, F. Hauff, K. Hoernle, U. Barckhausen, C. Lüter, B. Neuhaus) ....................................................................................................7 3.1. Christmas Island Seamount Province and Investigator Ridge....................................................7 3.2. Intraplate Volcanism and the “Great Plume Debate”...................................................................9 3.3. Indian Mantle Domain .................................................................................................................10 3.4. Internal Deformation of Oceanic Plates......................................................................................10 3.5. Plate Convergence in the Southeastern Asian Area .................................................................11 4. Cruise Narrative (R. Werner, K. Hoernle) ...............................................................................................12 5. Bathymetry and Rock Sampling (F. Hauff, R. Werner, D. Maicher, K. Hoernle)....................................17 5.1. Methods .......................................................................................................................................17 5.1.1. Bathymetry.....................................................................................................................17 5.1.2. Rock Sampling...............................................................................................................18 5.2. Sampling Report and Preliminary Results .................................................................................19 5.2.1. “Outsider” Seamount .....................................................................................................19 5.2.2. Investigator Ridge and Adjacent Features ...................................................................21 5.2.3. Cocos/Keeling Island Province .....................................................................................30 5.2.4. Northwestern Christmas Island Seamount Province. ..................................................33 5.2.5. Eastern Christmas Island Seamount Province.............................................................40 5.2.6. Southern Christmas Island Seamount Province ..........................................................47 5.2.7. Areas Adjacent to the Argo Basin.................................................................................53 5.2.8. Bathymetry and Hard Rock Sampling Summary .........................................................56 5.3. Volcaniclastic Rocks (D. Maicher) ..............................................................................................58 5.3.1 Classification of Volcaniclastic Rocks............................................................................59 5.3.2. CHRISP Volcaniclastic Deposits ..................................................................................60 5.3.3. Dredge Assemblages and Morphologies .....................................................................64 6. Magnetics (U. Barckhausen, A. Gibbons, M. Zeibig) ..............................................................................65 6.1. Magnetic data acquisition and processing (U. Barckhausen, M. Zeibig)..................................65 6.1.1. Marine Magnetics SeaSpy™ Gradiometer...................................................................65 6.1.2. Magson™ Fluxgate Magnetometer ..............................................................................66 6.1.3. Fluxgate Calibration.......................................................................................................67 6.1.4. Magnetic data processing .............................................................................................67 6.2. Preliminary interpretation of the magnetic profiles (U. Barckhausen, A. Gibbons)..................70 6.2.1. Magnetic Anomalies of the Wharton Basin ..................................................................70 6.2.2. Magnetic Anomalies of the Roo Rise and the Argo Abyssal Plain..............................73 7. Biology (C. Lüter, B. Neuhaus, A. Roth, R. Seidel) .................................................................................78 7.1. Methods .......................................................................................................................................78 7.1.1. Shipboard Collecting Procedures .................................................................................78 7.1.2. Meiofauna ......................................................................................................................78 7.1.3. Macrofauna ....................................................................................................................79 7.2. Preliminary Results and Discussion ...........................................................................................79 7.2.1. General Observations and Collecting Report...............................................................79 7.2.2. Meiofauna ......................................................................................................................80 7.2.3. Macrofauna ....................................................................................................................80 8. References ................................................................................................................................................82 Appendices: I. Sampling Summary II. Rock Description III. Volcaniclastic Rocks IV. Biological Sampling V. Overview Map: SO199 Sampling Sites 2 SUMMARY The research project SO199 CHRISP (CHRistmas Island Seamount Province and the Investigator Ridge: Age and Causes of Intraplate Volcanism and Geodynamic Evolution of the South-Eastern Indian Ocean) comprises petrological, volcanological, geochemical, geochronological, geophysical, and biological studies in the area of the northern Wharton Basin (South-East Indian Ocean). R/V SONNE cruise SO199 focused on the “Christmas Island Seamount Province”, a huge (~1,800 x 600 km) submarine volcanic province of unknown origin, and on the Investigator Ridge, a ~1,800 km long N-S