Integrated Ocean Drilling Program Expedition 301T preliminary report; Costa Rica hydrogeology; 20 August-10 September 2004

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doi: 10.2204/
Author(s): Kastner, Miriam; Hensley, Tabitha M.; Jannasch, Hans W.; Morris, Julie D.; Mukoyoshi, Hideki; Robertson, Gretchen A.; Solomon, Evan A.; Heesemann, Martin; Pettigrew, Thomas
Integrated Ocean Drilling Program, Expedition 301T Scientists, College Station, TX
Author Affiliation(s): Primary:
Scripps Institution of Oceanography, La Jolla, CA, United States
Monterey Bay Aquarium Research Institute, United States
Washington University, United States
Kochi University, Japan
Universität Bremen, Federal Republic of Germany
Source: Preliminary Report (Integrated Ocean Drilling Program), Vol.301T, 30p. Publisher: IODP Management International, College Station, TX, United States. ISSN: 1932-9423
Note: In English. 16 refs.
Summary: The Costa Rica hydrogeology operation was designed to replace CORK-II downhole instrument strings in holes drilled at Ocean Drilling Program Leg 205 Sites 1253 and 1255 (September-November 2002) off Costa Rica. The CORKs are instrumented in a fractured horizon in the oceanic section of the incoming plate (Site 1253) and in the decollement zone (Site 1255) to investigate fluid flow across the margin and its implications for the seismogenic zone and subduction factory. Operations during the cruise were successfully completed in less than 4 days, and the instrument strings were retrieved and replaced; only the lower osmotic fluid sampler OsmoSampler package from Site 1253 was lost. Because of the close proximity of the two Site 1253 OsmoSampler packages, this loss will have minimal impact on the data. All recovered instruments worked as expected, and the redeployed samplers and temperature loggers are configured for approximately 3.5 y duration. OsmoSampler fluids from each site were analyzed for ephemeral properties on board ship (salinity, pH, alkalinity, and ammonium) and subdivided for further postcruise studies. Postcruise analyses will provide a high-resolution time series of fluid chemistry and temperature over a 2 y period and, at Site 1255, fluid flow rates and relative flow directions, with implications for seismogenic zone activity, chemistry of the arc volcanoes, and solute fluxes into the ocean.
Year of Publication: 2004
Research Program: IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 21 Hydrogeology and Hydrology; Boreholes; Central America; Continental margin; Costa Rica; Downhole methods; East Pacific; Expedition 301T; Flows; Fluid phase; Fluid pressure; Ground water; Integrated Ocean Drilling Program; Leg 205; Middle America Trench; North Pacific; Northeast Pacific; ODP Site 1253; ODP Site 1255; Ocean Drilling Program; Pacific Ocean; Plate convergence; Plate tectonics; Pore water; Seismicity; Subduction zones
Coordinates: N093900 N093900 W0861100 W0861100
N093900 N093900 W0861100 W0861100
Record ID: 2008016928
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