A number of operational, practical, and strategic factors were considered when developing the operational plan for Leg 184. Briefly, these include

  1. Sites were selected to maximize recovery of different stratigraphic sections and different water depths. The northern continental margin sites comprise two transects: an eastern pair of sites that will focus on the Plio-Pleistocene section (Sites SCS-1 and SCS-2) at 2050 and 3190 m, respectively, and a western pair of sites that will focus on the Oligocene to Miocene section (Sites SCS-4 and SCS-5C) at 2093 and 3250 m, respectively.
  2. All sites are considered to be first priority, but Site SCS-3C is considered at risk if operational time is limited. Site SCS-5C is considered to be the highest priority as it is the only site that will recover the Oligocene to Miocene section of the SCS. Alternate Site SCS-5D or 5E may become a higher priority than SCS-3C, if the coring results at SCS-5C do not satisfactorily recover the early history of the monsoon.
  3. All sites will be triple piston cored (advanced hydraulic piston core [APC]) and extended core barrel (XCB) cored to total depth, with the possibility of double XCB if critical sections are not adequately recovered. The deeper sections of Site SCS-5C may be cored with the rotary core barrel system (RCB), if XCB penetration and recovery are not adequate.
  4. Because of the limited number of seismic crossing lines at proposed sites, the JOIDES Resolution will conduct a seismic reflection survey (~2 to 2.5 days at Sites SCS-2, 3C, 4, and 5C and, if required, Sites SCS-5D and 5E) to verify that the proposed sites are safe and to provide a better structural framework for interpreting the sediment accumulation patterns. Coring at all but SCS-1 is contingent on safety panel approval, which will be based on the survey data.
  5. Taking the above operational/coring considerations into account, the following sequence of operations is proposed: Depart Freemantle and transit to proposed Site SCS-9 and core. Then transit to Site SCS-1 and core. We will then conduct a seismic survey of northern sites to collect cross lines and select final site locations. Following the survey, we anticipate coring proposed Sites SCS-2, SCS-5C (or alternate), SCS-4, and SCS-3C in sequence before the final transit to Hong Kong.
  6. ODP has requested Exclusive Economic Zone (EEZ) clearance for all proposed sites. Site SCS-9 requires drilling in waters that are claimed by several nations and EEZ clearance of this site may therefore be more problematic than for the northern sites. If SCS-9 should not get approved, the remaining time will be used to achieve the objectives, and maximize recovery, at the other sites, including SCS-3C.

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