Two boreholes were drilled on the Costa Rica subduction zone to study the geochemical fluxes and related processes associated with sediment compaction, dewatering, and alteration. The holes were outfitted with modified CORKs (CORK-IIs) that include instruments capable of fluid sampling and measuring flow rates, temperature, and pressure. Fluids are sampled continuously within the décollement zone and in the uppermost oceanic crust with long-term OsmoSamplers for both dissolved ions and gases. The major advantage of the CORK-II is that samples and data can be retrieved without disrupting the pressurized horizons by temporarily opening them to hydrostatic pressures during instrument exchange. This paper describes the concepts, design, and deployment of CORK-IIs in Holes 1253A and 1255A.
1Jannasch, H.W, Davis, E.E., Kastner, M., Morris, J.D., Pettigrew, T.L., Plant, J.N., Solomon, E.A., Villinger, H.W., and Wheat, C.G., 2003. CORK-II: long-term monitoring of fluid chemistry, fluxes, and hydrology in instrumented boreholes at the Costa Rica subduction zone. In Morris, J.D., Villinger, H.W., Klaus, A., et al., Proc. ODP, Init. Repts., 205 [Online]. Available from World Wide Web: <http://www-odp.tamu.edu/publications/205_IR/chap_02/chap_02.htm>. [Cited
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2Monterey Bay Aquarium Research Institute, 7700 Sandholdt Road, Moss Landing CA 95039, USA.
Correspondence author: jaha@mbari.org
3Pacific Geoscience Center, Geological Survey of Canada, Box 6000, Sidney BC V8L 4B2, Canada.
4Scripps Institution of Oceanography, University of California at San Diego, La Jolla CA 92093, USA.
5Department of Earth and Planetary Sciences, Washington University, One Brookings Drive, St. Louis MO 63130-4899, USA.
6Ocean Drilling Program, Texas A&M University, 1000 Discovery Drive, College Station TX 77845-9547, USA.
7Department of Earth Sciences, University of Bremen, POB 330 440, Bremen, Germany.
8Institute of Marine Science, West Coast and Polar Regions Undersea Research Center, PO Box 475, Moss Landing CA 95039, USA.
Ms 205IR-102