Pliocene changes in tropical East Pacific upper ocean stratification; response to tropical gateways?

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doi: 10.2973/odp.proc.sr.202.211.2006
Author(s): Steph, Silke; Tiedemann, Ralf; Groeneveld, Jeroen; Sturm, Arne; Nürnberg, Dirk
Ocean Drilling Program, Leg 202, Shipboard Scientific Party, College Station, TX
Author Affiliation(s): Primary:
IFM-GEOMAR, Leibniz-Institute of Marine Sciences, Kiel, Federal Republic of Germany
Other:
Oregon State University, United States
Texas A&M University, United States
Instituto Geologico e Mineiro, Portugal
University of Cambridge, United Kingdom
National Taiwan Ocean University, Taiwan
University of California at Santa Cruz, United States
Universidad Salamanca, Spain
Woods Hole Oceanographic Institution, United States
Hokkaido University, Japan
Kochi University, Japan
Hobart and William Smith Colleges, United States
University of Bergen, Norway
Universität Bremen, Federal Republic of Germany
University of Southern California, United States
Université de Bordeaux I, France
Columbia University, United States
Princeton University, United States
University of Colorado at Boulder, United States
Servicio Nacional de Geologia y Mineria, Bolivia
Alfred Wegener Institute for Polar and Marine Research, Federal Republic of Germany
Volume Title: Proceedings of the Ocean Drilling Program; scientific results; Southeast Pacific paleoceanographic transects; covering Leg 202 of the cruises of the drilling vessel JOIDES Resolution; Valparaiso, Chile, to Balboa, Panama; Sites 1232-1242; 29 March-30 May 2002
Volume Author(s): Tiedemann, Ralf; Mix, Alan C.; Blum, Peter; Abrantes, Fatima F.; Benway, Heather; Cacho-Lascorz, Isabel; Chen, Min-Te; Delaney, Margaret L.; Flores, José-Abel; Giosan, Liviu; Holbourn, Ann E.; Irino, Tomohisa; Iwai, Masao; Joseph, Leah H.; Kleiven, Helga F.; Lamy, Frank; Lund, Steven P.; Martinez, Philippe; McManus, Jerry F.; Ninnemann, Ulysses S.; Pisias, Nicklas G.; Robinson, Rebecca S.; Stoner, Joseph S.; Sturm, Arne; Wara, Michael W.; Wei, Wuchang
Source: Proceedings of the Ocean Drilling Program; scientific results; Southeast Pacific paleoceanographic transects; covering Leg 202 of the cruises of the drilling vessel JOIDES Resolution; Valparaiso, Chile, to Balboa, Panama; Sites 1232-1242; 29 March-30 May 2002, Ralf Tiedemann, Alan C. Mix, Peter Blum, Fatima F. Abrantes, Heather Benway, Isabel Cacho-Lascorz, Min-Te Chen, Margaret L. Delaney, José-Abel Flores, Liviu Giosan, Ann E. Holbourn, Tomohisa Irino, Masao Iwai, Leah H. Joseph, Helga F. Kleiven, Frank Lamy, Steven P. Lund, Philippe Martinez, Jerry F. McManus, Ulysses S. Ninnemann, Nicklas G. Pisias, Rebecca S. Robinson, Joseph S. Stoner, Arne Sturm, Michael W. Wara and Wuchang Wei; Ocean Drilling Program, Leg 202, Shipboard Scientific Party, College Station, TX. Proceedings of the Ocean Drilling Program, Scientific Results (CD ROM), Vol.202, 51p. Publisher: Texas A&M University, Ocean Drilling Program, College Station, TX, United States. ISSN: 1096-2514
Note: In English. Includes appendix. 117 refs.CD-ROM format, ISSN 1096-2514; WWW format, ISSN 1096-7451; illus., incl. 1 plate, 2 tables, sketch map
Summary: A combination of stable isotope records and Mg/Ca temperature estimates of four different planktonic foraminiferal species from Ocean Drilling Program Site 1241 allows differentiation between temperature and salinity changes in the tropical east Pacific (TEP) upper water column during the Pliocene (∼5.7-2.1 Ma). The deviation of δ18O records and Mg/Ca temperature estimates from thermocline-dwelling planktonic foraminifers suggests that local changes in salinity exerted a much stronger control on Pliocene TEP upper ocean water mass signatures than previously assumed. The most pronounced Pliocene change in TEP upper ocean stratification was the shoaling of the thermocline from ∼4.8 to 4.0 Ma that was possibly triggered by changes in the configuration of low-latitude ocean gateways. During this time interval, mixed-layer temperatures and salinities remained relatively constant in contrast to a pronounced temperature (∼6°C) and salinity decrease at the bottom of the photic zone. This change led to a new state in the thermal structure of the TEP, as the thermocline remained relatively shallow until ∼2.1 Ma.
Year of Publication: 2006
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Alkaline earth metals; Biostratigraphy; Calcium; Cenozoic; Chemical ratios; East Pacific; Foraminifera; Gateways; Geochemistry; Invertebrata; Isotope ratios; Isotopes; Leg 202; Magnesium; Metals; Mg/Ca; Microfossils; Neogene; O-18/O-16; ODP Site 1241; Ocean Drilling Program; Oxygen; Pacific Ocean; Paleo-oceanography; Paleosalinity; Paleotemperature; Pliocene; Protista; Reconstruction; South Pacific; Southeast Pacific; Stable isotopes; Stratification; Tertiary; Thermocline; Tropical environment
Coordinates: N055100 N055100 W0862700 W0862700
Record ID: 2007051094
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