The 268-nmi transit to Site 1240 (proposed Site PAN-2A) required 22.2 hr at an average speed of 12.1 kt. Shipboard 3.5-kHz precision depth recorder (PDR) records were used to check the final site characteristics by comparison with precruise survey data. The vessel was on station by 0100 hr on 16 May 2002.
Hole 1240A was initiated with the advanced piston corer (APC) and the drill bit at 2928 meters below rig floor (mbrf) at 0750 hr on 16 May. The seafloor depth that was estimated by the amount of recovery of the first core was 2934.0 mbrf. This was 2.4 m shallower than the corrected PDR depth of 2936.4 mbrf. Piston coring penetrated the sediment section to 253 meters below seafloor (mbsf) without resorting to the extended core barrel (XCB). Coring in the hole was terminated when the last piston core (28H) did not achieve a full stroke and was recovered with a bent core barrel, damaged cutting shoe, and 3.87 m of basaltic gravel and nannofossil ooze. The APC cored 253.0 m and recovered 264.0 m (recovery = 104%) (Table T1).
The nonmagnetic core barrel was deployed on even-numbered cores up to and including Core 18H, starting with Core 2H. A total of six core barrels were drilled over starting with Core 22H. The piston cores were oriented starting with Core 4H. Downhole temperature measurements were taken with the APC temperature (APCT) tool at various depths as summarized in Table T1. The odoriferous cores were stored on the catwalk rack to degas H2S subsequent to splitting. Headspace measurements on the cores yielded trace amounts of methane (<300 ppm) and ethane (<2 ppm). No higher molecular weight hydrocarbon compounds were detected. The bit was pulled free of the seafloor at 1145 hr on 17 May.
The vessel was offset 10 m west of Hole 1240A. Prior to coring, a bottom water temperature measurement was obtained with the APCT tool with the bit positioned just above the seafloor. To obtain the desired stratigraphic overlap with the first hole, the bit was placed at 2931.0 mbrf and Hole 1240B was initiated with the APC at 1320 hr. The seafloor depth derived from the recovery of the first core was 2931.8 mbrf. Piston coring combined with a 2-m drilled interval (75.2-77.2 mbsf) deepened the hole to 248.2 mbsf. The cored interval was 246.2 m with 254.8 m recovered (recovery = 104%) (Table T1).
The nonmagnetic core barrel was deployed on odd-numbered cores up to and including Core 21H. Eight core barrels were drilled over in this hole starting with Core 19H. The cores were oriented starting with Core 3H. The depths of downhole temperature measurements are listed in Table T1. The bit was pulled free of the seafloor at 1400 hr on 18 May.
The vessel was offset 10 m west of Hole 1240B, and Hole 1240C was initiated with the APC at 1505 hr on 18 May. The bit was positioned at a depth of 2934.0 mbrf, or 2.2 m deeper than the calculated mudline depth of Hole 1240B (2931.8 mbrf). Piston coring deepened the hole to 80.2 mbsf. Two intervals were drilled to maintain the proper overlap with the data from the previous two holes (0.0-2.2 and 32.7-42.2 mbsf). The cored interval was 76.0 m with 75.3 m recovered (recovery = 99%) (Table T1).
The nonmagnetic core barrel was deployed on even-numbered cores. No core barrels were drilled over. Cores were oriented starting with Core 3H. Additional downhole temperature measurements are summarized in Table T1. The temperature measurements from all holes yielded a gradient of 2.6°C/100 m. The bit was pulled free of the seafloor at 2340 hr on 18 May.
The vessel was offset 10 m west of Hole 1240C, and Hole 1240D was initiated with the APC at 0025 hr on 18 May. The bit was positioned at a depth of 2935.0 mbrf, or 3.2 m deeper than the calculated mudline depth of Hole 1240B (2931.8 mbrf). Piston coring and drilling deepened the hole to 31.7 mbsf. One interval was drilled to maintain the proper overlap with the data from the previous two holes (0.0-3.2 mbsf). The cored interval was 28.5 m with 28.6 m recovered (recovery = 100.4%) (Table T1). The nonmagnetic core barrel was deployed on the two odd-numbered cores. Core 3H was oriented.
The vessel was secured for transit and departed for Site 1241 at 0915 hr on 19 May.