The 237-nmi voyage to Site 1085 was accomplished at an average speed of 10.1 kt. The speed of the vessel was adversely affected because of the northward flowing Benguela Current and rough seas. The vessel approached the Global Positioning System coordinates of the site, and a beacon was deployed at 1215 hr on 26 September. Hole 1085A was spudded with the APC at 1653 hr. The seafloor depth was estimated from the recovery of the first core at 1713.2 meters below sea level (mbsl). APC coring advanced without incident to 305.0 mbsf (Cores 175-1085A-1H through 33H), which was considered refusal depth for piston coring, with 96.2% recovery (Table 1; also see expanded core summary table on CD-ROM, back pocket, this volume). Cores were oriented starting with Core 4H. Adara heat-flow measurements were taken at 41.7 mbsf (5H), 60.7 mbsf (7H), 79.7 mbsf (11H), and 231.7 mbsf (25H). XCB coring advanced to 605.0 mbsf (64X), with 100.7% recovery.
In preparation for logging, an aluminum go-devil was dropped to ensure the opening of the lockable float valve. After the hole was flushed with a high-viscosity mud treatment, the bit was placed at the logging depth of 88.3 mbsf. Hole 1085A was logged with a full suite of sensors. For each run, the pipe was set at 88.3 mbsf and pulled back to 60.0 mbsf during logging. The wireline logging heave compensator was started when the logging tools reached the mudline.
Logging operations began at 0030 hr on 29 September. The first log was conducted with the seismostratigraphic suite (25.8 m long). This suite was made up of the spectral gamma-ray (NGT), long-spacing sonic (LSS), phasor dual-induction (DIT), and Lamont-Doherty high-resolution temperature (TLT) sondes. This tool string was deployed in the pipe at 0110 hr and logged the hole up from 603.2 mbsf. The tool string was recovered at 0510 hr. The second log was with the lithoporosity suite (19.5 m long) and included the hostile environment gamma spectrometry (HNGS), accelerator porosity (APS), lithodensity (LDS), and TLT sondes. The tool string was deployed at 0620 hr, logged the hole up from 600.7 mbsf, and was retrieved at 1020 hr. The third log was made with the FMS suite (12.10 m long) and included the NGT, general purpose inclinometer, and FMS sondes. This tool string was deployed at 1125 hr and logged the hole up from 600.7 mbsf. The tool string was recovered by 1400 hr. The fourth and last log was made with the magnetic susceptibility suite (11.8 m long) and included the NGT, magnetic susceptibility, and nuclear resonance magnetometer sondes. The tool was deployed in the pipe at 1425 hr and logged the hole up from 600.7 mbsf. It was retrieved at 1715 hr on 29 September. The logging equipment was rigged down by 1800 hr. The drill string was then pulled out of the hole with the bit clearing the seafloor at 1815 hr on 29 September, thereby ending operations at Hole 1085A.
The vessel was offset 30 m to the west, and Hole 1085B was spudded with the APC at 1915 hr. The recovery of the first core established the seafloor depth at 1713.0 mbsl. APC coring advanced without incident to refusal at 321.2 mbsf (Cores 175-1085A-1H through 35H), with 101.7% recovery (Table 1). The last two cores did not achieve full piston strokes because of the indurated sediment. Cores were oriented starting with Core 3H. The drill string was retrieved, with the bit clearing the seafloor at 1730 hr. After the beacon, hydrophones, and thrusters were retracted and the drilling equipment was secured, the vessel was under way to the next site at 2330 hr on 30 September.