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Ifm-Geomar Report FS SONNE Fahrtbericht / Cruise Report SO-210 ChiFlux - Identification and investigation of fluid flux, mass wasting and sediments in the forearc of the central Chilean subduction zone – Valparaiso - Valparaiso 23.09. – 01.11.2010 IFM-GEOMAR REPORT Berichte aus dem Leibniz-Institut für Meereswissenschaften an der Christian-Albrechts-Universität zu Kiel Nr. 44 Mai 2011 FS SONNE Fahrtbericht / Cruise Report SO-210 ChiFlux - Identification and investigation of fluid flux, mass wasting and sediments in the forearc of the central Chilean subduction zone – Valparaiso - Valparaiso 23.09. – 01.11.2010 Berichte aus dem Leibniz-Institut für Meereswissenschaften an der Christian-Albrechts-Universität zu Kiel Nr. 44 Mai 2011 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: Peter Linke 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 2 SONNE 210 / CHIFLUX Cruise Report Table of Content: 1 Summary / Zusammenfassung .............................................................................................. 4 2 Introduction ........................................................................................................................... 6 2.1 Objectives.......................................................................................................................... 6 2.2 Geological Setting of the Study Area and Maps ............................................................... 7 3 Participants ......................................................................................................................... 11 3.1 Scientific crew................................................................................................................. 11 3.2 Ship’s crew ...................................................................................................................... 12 4 Cruise Narrative .................................................................................................................. 14 5 Scientific Equipment .......................................................................................................... 20 5.1 Shipboard Equipment ...................................................................................................... 20 5.1.1 Parasound .................................................................................................................... 20 5.1.2 Kongsberg EM120 multibeam bathymetry system ..................................................... 20 5.2 Water column measurements .......................................................................................... 22 5.3 Seafloor observations by OFOS ...................................................................................... 23 5.4 ROV Operations .............................................................................................................. 24 5.5 Lander Operations ........................................................................................................... 26 5.6 TV-Grab Operations ....................................................................................................... 30 5.7. Sediment Sampling and Sedimentology ......................................................................... 31 5.8. Zoology ........................................................................................................................... 32 5.9. Microbiological Studies .................................................................................................. 33 5.10. Pore Water Geochemistry ........................................................................................... 34 5.11. Volcanology ................................................................................................................ 35 6. Work Completed and First Results ..................................................................................... 36 6.1. Hydroacoustic Work ....................................................................................................... 36 6.1.1 Parasound .................................................................................................................... 36 6.1.2 EM120 ......................................................................................................................... 40 6.2. Water Column Studies .................................................................................................... 43 6.3. Seafloor Observations (OFOS, ROV) ............................................................................. 46 6.4. ROV Deployment and Sampling .................................................................................... 51 6.5. Lander Deployments ....................................................................................................... 55 6.6 TV-Grab Deployments .................................................................................................... 58 6.7 Sediment Sampling and Sedimentology ......................................................................... 59 6.8 Zoological Studies........................................................................................................... 62 6.9 Microbiological Studies .................................................................................................. 67 Cruise Report SONNE 210/CHIFLUX 3 6.10 Pore Water Geochemistry ........................................................................................... 70 7. Acknowledgements ......................................................................................................... 76 8. References ....................................................................................................................... 76 Annex I: List of Stations ............................................................................................................ 78 Annex II: Carbonate Sample Description .................................................................................. 84 Annex III Zoological Sample Collection ................................................................................... 90 Annex IV: Core Descriptions ..................................................................................................... 94 4 SONNE 210 / CHIFLUX Cruise Report 1 Summary / Zusammenfassung (P. Linke) Cruise SO210 with RV SONNE to the active continental margin off Chile was conducted by shiptime exchange with RV METEOR. Funds for mobilizing the research team were provided by the German Science Foundation (DFG) in conjunction with the Collaborative Research Centre (SFB) 574 of the University of Kiel. In the first years, the SFB 574 investigated the pathways and fluxes of volatiles through the erosive subduction zone off Central America. For comparison, the studies were extended to the accretionary margin off Central Chile. Cruise SO210 is the last cruise conducted in the framework of SFB 574 and based on investigations of previous SFB-cruises on the RVs VIDAL GORMAZ and JAMES COOK. The first leg of cruise SO210 was dedicated to long gravity coring for volcanic ash layers from the erruptive Southern Volcanic Zone (SVZ) of the Andes that were either deposited as fallouts onto the incoming Nazca Plate or transported down the slope and across the Chile Trench. Eight gravity cores of 12 m length were retrieved seaward of the Chile Channel on the outer rise of the Nazca Plate. The second goal for coring was the description and dating of previously mapped submarine landslides as well as retrieval of slide-related material for geo-technical experiments. As the deployment frame for long coring had to be removed on the second leg we continued coring for mass-wasting and geochemistry with short cores. Ten gravity cores of 3 or 6 m barrel length were retrieved upslope of slides, the glide plane and redeposited material downslope of the slide evacuation area. This sampling activity was supported by detailed acoustic surveys with Parasound and multibeam to remap critical areas for mass wasting in search for events, e.g. triggered by the recent Mw 8.8 Maule Earthquake, such as flanks of submarine canyons or previously detected submarine slides and to fill data gaps in the existing bathymetric data. The major activity of the entire cruise was dedicated to the search and detailed sampling of manifestations of fluid discharge activity on the Chilean forearc. A total of 11 deployments with the video sled OFOS and 12 dives by the ROV KIEL 6000 were conducted for ground-truthing of information which indicated possible seep activity and has been obtained during previous cruises to the Chilean forearc. In five working areas we found manifestations of fluid discharge. In these areas the survey was followed by an intense sampling of bottom water, sediments, carbonates, mega and meiofauna and the deployment of instrumentation on the seafloor. The goal of these deployments was to measure in situ seabed methane
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