Kastern, Mirian and Malone, Mitchell J. (2004): Integrated Ocean Drilling Program, Expedition 301T scientific prospectus; Costa Rica hydrogeology

IODP 301
ODP 205
ODP 205 1253
ODP 205 1255



Kastern, Mirian
Scripps Institution of Oceanography, La Jolla, CA, United States

Malone, Mitchell J.
Integrated Ocean Drilling Program, United States

Integrated Ocean Drilling Program, Expedition 301T scientific prospectus; Costa Rica hydrogeology
Scientific Prospectus (Integrated Ocean Drilling Program)
IODP Management International, College Station, TX, United States
37 pp.
The Costa Rica hydrogeology operation proposes to replace CORK-II downhole instrument strings in holes drilled at Ocean Drilling Program (ODP) 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 and in the decollement zone to investigate fluid flow across the margin and its implications for the seismogenic zone and subduction factory. During Atlantis cruise 11-8 (27 February-7 March 2004) the Alvin was unable to recover the downhole osmotic fluid samplers and miniaturized temperature loggers and was thus unable to deploy the new instrument strings. Apparently, soft debris in the borehole buried the latch, and the limited bottom time, lighter-weight running tools necessary for the Alvin, and limited capacity of the wellhead winch frustrated recovery efforts. These impediments present no significant obstacles to a drillship, as discussed below. Pressure data downloaded from the samplers at Sites 1253 and 1255 record two transient events; evaluation of temperature and fluid chemistry data from the downhole instruments at the two sites is critical to investigating strain or hydrological origins of the pressure events. The osmotic samplers currently installed were designed to collect a time series of samples for fluid and gas analyses over a 2 y period; after 2 y, samples and the information they contain are progressively lost. The temperature loggers will stop recovering data after 6 October 2004. The drillship work proposed here will be done during the transit following Integrated Ocean Drilling Program (IODP) Expedition 301 after the scheduled port call at Astoria, Oregon, en route to the Panama Canal.
Coverage:Geographic coordinates:
West:-86.1100East: -86.1100

Oceanography; Hydrogeology; boreholes; Central America; circulation; continental margin; Costa Rica; crust; drilling; East Pacific; Expedition 301; expeditions; hydrogeology; Integrated Ocean Drilling Program; Leg 205; marine drilling; marine sediments; Middle America Trench; North Pacific; Northeast Pacific; Ocean Drilling Program; oceanic crust; ODP Site 1253; ODP Site 1255; Pacific Ocean; planning; pore water; sampling; sediments; tracers;