The drilling strategy for Leg 184 reflected both the scientific priorities for prospective sites and a number of operational, practical, and strategic factors. Initially, Leg 184 was planned to core six sites: one on the southern margin and five on the northern margin. Despite a delayed departure from Fremantle, Australia, and a diversion to Singapore to repair the ship's 10-cm radar, we cored 17 holes at six sites (Sites 1143-1148) (Table 1; Figs. 8, 9). The lowest priority proposed site SCS-3 was sacrificed in favor of deepening Sites 1143, 1146, and 1148. At all sites, our drilling strategy was to triple core with the advanced hydraulic piston corer (APC) system to refusal and deepen at least one hole with the extended core barrel (XCB) system to the maximum approved depth. Site 1148 was the single site where only two holes were drilled. All sites deeper than 400 meters below seafloor (mbsf) (Sites 1143, 1144, 1146, and 1148) were wireline logged as planned.

Our drilling plan was to first core the southern Site 1143 enroute to the northern operations area. Following a brief seismic survey of proposed sites SCS-4, SCS-5C, -5D, and -5E, as required for final safety approval, we elected to core SCS-1 (Site 1144) which had prior Pollution Prevention and Safety Panel (PPSP) approval. During the occupation of Site 1144, we received approval to core the surveyed sites with minor changes in locations. Our final site selection on the northern continental margin was aimed to maximize recovery of different stratigraphic sections at different water depths. Site 1144 (proposed site SCS-1) at a water depth of 2037 m focused on the Pleistocene section, and Sites 1146 (SCS-4) and 1148 (SCS-5C) centered on the Oligocene to Pliocene section at water depths of 2092 and 3294 m, respectively.

Scientific Measurements Strategy

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