DRILLING STRATEGY
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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