Phosphorus, barium, manganese, and uranium concentrations and geochemistry, Nazca Ridge Site 1237 sediments

Online Access: Get full text
doi: 10.2973/odp.proc.sr.202.205.2006
Author(s): Chun, Cecily O. J.; Delaney, Margaret L.
Ocean Drilling Program, Leg 202, Shipboard Scientific Party, College Station, TX
Author Affiliation(s): Primary:
University of California at Santa Cruz, Ocean Sciences Department, Santa Cruz, CA, United States
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
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, 19p. Publisher: Texas A&M University, Ocean Drilling Program, College Station, TX, United States. ISSN: 1096-2514
Note: In English. 33 refs.CD-ROM format, ISSN 1096-2514; WWW format, ISSN 1096-7451; illus., incl. 3 tables
Summary: We determined the sedimentary concentrations of phosphorus (P), barium (Ba), manganese (Mn), titanium (Ti), aluminum (Al), and uranium (U) for sediment samples from the southeast Pacific Nazca Ridge, Ocean Drilling Program Site 1237. This unique record extends to 31 Ma over 360 meters composite depth (mcd), recording depositional history as the site progressed eastward over its paleohistory. We sampled with a temporal resolution of ∼0.2 m.y. throughout the sequence, equivalent to an average spacing of 1.63 m/sample. Concentrations of sequentially extracted components of P (oxide-associated, authigenic, organic, and detrital) increase toward the modern. Al/Ti ratios indicate that the background detrital source material is consistent with upper continental crust. U enrichment factors (UEFs) generally exceed crustal values and indicate slightly reducing environments. However, authigenic U precipitation can also be influenced by the organic carbon rain rate and may not be solely an indicator of redox conditions. Dramatic changes in MnEFs at ∼162 mcd, from values between 12 and 93 to values <12 after this depth, and a sharp color contact boundary lead us to believe that a paleoredox boundary from an oxygenated to a more reducing depositional environment occurred near this depth. Estimates of biogenic barite concentrations from a total sediment digestion technique (Baexcess) are greater than those from a barite extraction (Babarite) for selected samples across the entire depth range. Applying a range of Ba/Ti ratios from different source materials to correct for detrital inputs does not change the lack of agreement with Babarite concentrations. Reactive P (Preactive) concentrations (the sum of oxide-associated, authigenic, and organic P concentrations) increase toward the modern with values typically <12 µmol P/g from the base of our record through ∼100 mcd, with a gradual increase to concentrations >15 µmol P/g. Baexcess follows the same general trends as Preactive, with concentrations <14 µmol Ba/g in the lower portion of the record to values >15 µmol Ba/g. Accumulation rate records of these proxies will be needed to infer paleoproductivity. Preactive/Baexcess ratios, an indicator of the relative burial of the nutrient P to organic carbon export, exhibit higher values, similar to modern, from the base of our record through ∼180 mcd. The remainder of the record exhibits values lower than modern, indicating that organic carbon export to the sediments was higher relative to nutrient burial.
Year of Publication: 2006
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Actinides; Alkaline earth metals; Barium; Cenozoic; Chemical composition; Concentration; Depositional environment; East Pacific; Geochemistry; Leg 202; Manganese; Marine sediments; Metals; Nazca Ridge; Nutrients; ODP Site 1237; Ocean Drilling Program; Organic compounds; Pacific Ocean; Paleo-oceanography; Paleoenvironment; Phosphorus; Quaternary; Sediments; South Pacific; Southeast Pacific; Tertiary; Uranium
Coordinates: S160000 S160000 W0762300 W0762300
Record ID: 2007051090
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.