Chemical and isotopic compositions of pore fluids and sediments from across the Middle America Trench, offshore Costa Rica

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doi: 10.2973/odp.proc.sr.205.208.2006
Author(s): Kastner, Miriam; Solomon, Evan A.; Wei, Wei; Chan, Lui H.; Saether, Ola M.
Ocean Drilling Program, Leg 205, Shipboard Scientific Party, College Station, TX
Author Affiliation(s): Primary:
Scripps Institution of Oceanography, La Jolla, CA, United States
Other:
Universität Bremen, Federal Republic of Germany
Texas A&M University, United States
Southampton Oceanography Centre, United Kingdom
Woods Hole Oceanographic Institution, United States
Dalhousie University, Canada
Japan Agency for Marine-Earth Science and Technology, Japan
University of California San Diego, United States
University of Wyoming, United States
University of Florida, United States
Eidgenössische Technische Hochschule-Zentrum, Switzerland
Universita degli Studi di Modena, Italy
Louisiana State University, United States
Geological Survey of Norway, Norway
Volume Title: Proceedings of the Ocean Drilling Program; scientific results; fluid flow and subduction fluxes across the Costa Rica convergent margin; implications for the seismogenic zone and subduction factory; covering Leg 205 of the cruises of the Drilling Vessel JOIDES Resolution; Victoria, Canada, to Balboa, Panama; Sites 1253-1255; 2 September-6 November 2002
Volume Author(s): Morris, Julie D.; Villinger, Heinrich W.; Klaus, Adam; Cardace, Dawn M.; Chavagnac, Valerie M. C.; Clift, Peter D.; Haeckel, Matthias; Hisamitsu, Toshio; Kastner, Miriam; Pfender, Marion; Saffer, Demian M.; Santelli, Cara; Schramm, Burkhard; Screaton, Elizabeth J.; Solomon, Evan A.; Strasser, Michael; Moe, Kyaw Thu; Vannucchi, Paola
Source: Proceedings of the Ocean Drilling Program; scientific results; fluid flow and subduction fluxes across the Costa Rica convergent margin; implications for the seismogenic zone and subduction factory; covering Leg 205 of the cruises of the Drilling Vessel JOIDES Resolution; Victoria, Canada, to Balboa, Panama; Sites 1253-1255; 2 September-6 November 2002, Julie D. Morris, Heinrich W. Villinger, Adam Klaus, Dawn M. Cardace, Valerie M. C. Chavagnac, Peter D. Clift, Matthias Haeckel, Toshio Hisamitsu, Miriam Kastner, Marion Pfender, Demian M. Saffer, Cara Santelli, Burkhard Schramm, Elizabeth J. Screaton, Evan A. Solomon, Michael Strasser, Kyaw Thu Moe and Paola Vannucchi; Ocean Drilling Program, Leg 205, Shipboard Scientific Party, College Station, TX. Proceedings of the Ocean Drilling Program, Scientific Results (CD ROM), Vol.205, 21p. Publisher: Texas A&M University, Ocean Drilling Program, College Station, TX, United States. ISSN: 1096-2514
Note: In English. Data report; available only on CD-ROM in PDF format and on the Web in PDF or HTML. 15 refs.CD-ROM, ISSN 1096-2514; WWW, ISSN 1096-7451; illus., incl. 2 tables
Summary: Pore fluid and sediment chemical and isotopic data were obtained for samples from Ocean Drilling Program (ODP) Leg 205 Sites 1253, 1254, and 1255 in the Costa Rica subduction zone. The chemical and isotopic data reported here were generated in our shore-based laboratories to complement shipboard inorganic geochemical data. Li isotopic analyses were carried out by L. H. Chan at Louisiana State University (USA). The data reported herein include fluoride, bromide, rubidium, cesium, and barium concentrations; Li and Sr isotopic compositions in pore fluids; and Rb, Cs, and Ba concentrations in representative bulk sediments. The data also include new pore fluid fluoride and bromide concentrations from corresponding ODP Leg 170 Sites 1039, 1040, and 1043. O. M. Saether's Site 1039 and 1040 fluoride concentration data are shown for comparison. Basal sediment fluoride concentrations and Li and Sr isotope ratios at both Sites 1253 and 1039 show reversals that approach modern seawater values. Br/Cl ratios are, however, conservative throughout the sediment section at Sites 1039 and 1253. The observed sharp F and Br concentration maxima, Rb and K concentration minima, the most radiogenic 87Sr/86Sr ratios, and highest δ7Li values along the decollement and fracture zone (Sites 1040, 1043, 1254, and 1255) strengthen the evidence obtained during Leg 170 that a deeply sourced fluid, originating from fluid-rock reactions at ∼150°C and corresponding to between 10 and 15 km depth, is transporting solutes to the ocean. An additional interesting observation is the positive relationship between F and Ca concentrations, both at the oceanic reference sites (1039 and 1253) and particularly in the de2.collement and fracture zone at Sites 1040 and 1254. The origin of this relationship is being investigated. Fluoride, an important metal-complexing agent, is highly enriched in the deep-sourced fluid identified at Sites 1040 and 1254. Complexation with F may therefore help to explain some of the observed trace metal concentrations in arc volcanic rocks.
Year of Publication: 2006
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 07 Marine Geology and Oceanography; Alkali metals; Alkaline earth metals; Central America; Concentration; Costa Rica; East Pacific; Geochemistry; Hydrochemistry; Isotope ratios; Isotopes; Leg 205; Li-7/Li-6; Lithium; Marine sediments; Metals; Middle America Trench; North Pacific; Northeast Pacific; Ocean Drilling Program; Pacific Ocean; Pore water; Sea water; Sediments; Sr-87/Sr-86; Stable isotopes; Strontium; Variations
Coordinates: N093800 N094000 W0861000 W0861200
Record ID: 2007025134
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