SURVEY STRATEGYAll sites included in this prospectus were surveyed and approved for coring by the Pollution Prevention and Safety Panel (PPSP). However, no crossing seismic line is available at Site SEPAC 13B. To optimize site locations, a short survey (~7 hr) will be conducted over proposed Sites SEPAC-13B and SEPAC-14A using the JOIDES Resolution's 80 in3 air gun on approach to the sites. Alternate Site SEPAC-19A has no crossing line, and if it is drilled a short (~2 hr) survey using the JOIDES Resolution's 3.5-kHz profiler will be executed to optimize the site location within the basin.
DRILLING STRATEGYAll sites will be triple-cored with the advanced piston corer (APC) to refusal. APC refusal depth is estimated at 150-250 meters below seafloor (mbsf). The mudline should be recovered in at least two holes at each site. Additional short APC holes may be drilled if this is required to achieve complete stratigraphic coverage (i.e., to eliminate all coring gaps and disturbed intervals in a composite section) in the APC interval. If the target depth is greater than the APC refusal depth, one hole (usually hole B) will be deepened with the extended core barrel (XCB). A second XCB interval may be cored at some sites if time becomes available or if the results warrant such an effort. Based on coring and logging time estimates, eight high-priority sites can be cored in the time available (Table 1). The sequence of drilling will essentially follow the south-north track of the ship from Valparaiso to Balboa. It is expected that at least one more high-priority site (SEPAC-19A and/or COC-3A) can be drilled using modest time gains, including an early departure and faster transits and coring. Depending on the coring results and the time available after completion of the southern area primary sites (SEPAC-14A, 13B, and 9A), contingency Site SEPAC-19A may be cored before departing north. If time is available later in the cruise, Site COC-3A is expected to be the first contingency site to be cored in the northern area.
If further time becomes available during the leg, the contingency plans include coring at second priority (alternate) sites (Table 2) and/or coring additional XCB intervals in an attempt to extend the composite section below the APC interval.
Logging Plan | Table of Contents