Integrated Ocean Drilling Program Expedition 339 preliminary report; Mediterranean outflow; environmental significance of the Mediterranean outflow water and its global implications; 16 November 2011-16 January 2012

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doi: 10.2204/iodp.pr.339.2012
Author(s): Hernández-Molina, Francisco J.; Stow, Dorrik A. V.; Alvarez Zarikian, Carlos; Williams, Trevor; Lofi, Johanna; Acton, Gary D.; Bahr, André; Balestra, Barbara; Ducassou, Emmanuelle; Flood, Roger D.; Flores, José-Abel; Furota, Satoshi; Grunert, Patrick; Hodell, David A.; Jiménez-Espejo, Francisco J.; Kim, Jin Kyoung; Krissek, Lawrence A.; Kuroda, Junichiro; Li Baohua; Lourens, Lucas; Miller, Madeline D.; Nanayama, Futoshi; Nishida, Naohisa; Richter, Carl; Sanchez Goni, Maria F.; Sierro Sánchez, Francisco J.; Singh, Arun D.; Sloss, Craig R.; Takashimizu, Yasuhiro; Tzanova, Alexandrina; Voelker, Antje; Xuan, Chuang
Integrated Ocean Drilling Program, Expedition 339 Scientists, College Station, TX
Author Affiliation(s): Primary:
Universidad de Vigo, Departmento Geociencias Marinas, Vigo, Spain
Other:
Heriot-Watt University, United Kingdom
Integrated Ocean Drilling Program, United States
Lamont-Doherty Earth Observatory, United States
Université de Montpellier II, France
University of California-Davis, United States
University of Frankfurt, Germany
Queens College, United States
Université de Bordeaux I, France
State University of New York-Stony Brook, United States
Universidad de Salamanca, Spain
Hokkaido University, Japan
University of Graz, Austria
University of Cambridge, United Kingdom
Japan Agency for Marine, Earth Science and Technology, Japan
Korea Ocean Research and Development Institute, South Korea
Ohio State University, United States
Nanjing Institute of Geology and Palaeontology, China
Utrecht University, Netherlands
California Institute of Technology, United States
AIST/Geological Survey of Japan, Japan
University of Louisiana, United States
Banaras Hindu University, India
Queensland University of Technology, Australia
Niigata University, Japan
Brown University, United States
Geological Survey of Portugal, Portugal
Oregon State University, United States
Source: Preliminary Report (Integrated Ocean Drilling Program), Vol.337, 97p. Publisher: IODP Management International, College Station, TX, United States. ISSN: 1932-9423
Note: In English. 122 refs.
Summary: During Integrated Ocean Drilling Program Expedition 339, five sites were drilled in the Gulf of Cadiz and two sites were drilled off the West Iberian margin from November 2011 to January 2012. Total length of recovered core is 5447 m, with an average recovery of 86.4%. The Gulf of Cadiz was targeted for drilling as a key location for the investigation of Mediterranean Outflow Water (MOW) through the Strait of Gibraltar gateway and its influence on global circulation and climate. The gulf is also a prime area for understanding the effects of tectonic activity on evolution of the Strait of Gibraltar gateway and margin sedimentation. Drilling penetrated into the Miocene at two sites in the Gulf of Cadiz, where sedimentary record showed a strong MOW signal following the opening of the Strait of Gibraltar gateway. Preliminary results indicate contourite deposition from 4.2 to 4.5 Ma, although subsequent research will establish whether this deposition dates from the first onset of MOW. The Pliocene succession, penetrated at four sites, displays characteristics consistent with low bottom-current activity linked with weak MOW. Significant widespread unconformities at 3.0-3.2 and 2.2-2.4 Ma are interpreted as a signal of intensified MOW, especially from ∼2.4 Ma. The Quaternary succession displays characteristics consistent with a much more pronounced phase of contourite drift development, with two distinct periods of increased MOW activity separated by a widespread unconformity at ∼0.9 Ma related to even higher MOW. Following this unconformity, the final phase of drift evolution established the contourite depositional system architecture we see today. There is significant climate control on this evolution of MOW and bottom-current activity. However, from the closure of the Atlantic-Mediterranean gateways in Spain and Morocco around 6 Ma to the opening of the Strait of Gibraltar gateway at 5.3 Ma, even stronger tectonic control affected margin development, downslope sediment transport, and contourite drift evolution. Based on the timing of events recorded in the sedimentary record, we propose tectonic pulsing in the region linked with small movements of the African and Iberian plates. The Gulf of Cadiz is the world's premier contourite laboratory and thus presents an ideal testing ground for the contourite paradigm. Following recovery of >4.5 km of contourite cores, existing models for contourite deposition are found to be sound. Further study of these models will undoubtedly allow us to resolve outstanding issues of depositional processes, drift budgets, and recognition of fossil contourites in the ancient record onshore. The expedition also verified the presence of a more than expected quantity and extensive distribution of contourite sands that are clean and well sorted. These sands represent a completely new and important exploration target for potential oil and gas reservoirs. Preliminary work has shown a remarkable record of orbital-scale variation in bulk sediment properties of contourites at several of the drift sites and good correlation between all sites. Climate control on contourite sedimentation is clearly significant at this scale; further work will determine the nature of controls at the millennial scale.
Year of Publication: 2012
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; Boreholes; Cenozoic; Continental margin; Contourite; Cores; Europe; Expedition 339; Geophysical methods; Geophysical profiles; Geophysical surveys; Gulf of Cadiz; IODP Site U1385; IODP Site U1386; IODP Site U1387; IODP Site U1388; IODP Site U1389; IODP Site U1390; IODP Site U1391; Iberian Peninsula; Integrated Ocean Drilling Program; Lithostratigraphy; Magnetic properties; Magnetic susceptibility; Magnetostratigraphy; Marine sediments; Mediterranean Outflow Water; Neotectonics; North Atlantic; Northeast Atlantic; Ocean circulation; Paleoclimatology; Paleogeography; Paleomagnetism; Portugal; Quaternary; Sediments; Seismic methods; Seismic profiles; Southern Europe; Spain; Surveys; Tectonics; Tertiary; Vertical seismic profiles; Well logs
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Record ID: 2012098507
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