Leg 184 began at 0730 hr on 11 February 1999 when the first line was passed ashore at the Victoria Quay in Fremantle, Australia. A number of engineering tasks were accomplished during the port call, including the installation of a new housing unit (penthouse), a container to house the microbiology laboratory on top of the lab stack, a vegetable chiller on the sun deck, and the replacement of the boom on Crane 2. The arrival of several freight containers that contained critical engine parts was delayed, and the vessel had to remain in port 2.5 days beyond the planned departure at 0600 hr on 16 February. At 1730 hr on 18 February, the last line was released from Victoria Quay, and the vessel cleared the harbor.
Site 1143 in the Nansha or Spratly Island area is located in an area that required special diplomatic efforts and safety protocols, which were finalized during the eventful 2800-nmi transit. Before the JOIDES Resolution could proceed to the prospective site, it required approval of the four political entities that lay claim to the region. Three countries (People's Republic of China [PRC], Vietnam, and the Philippines) had given formal consent before the drillship left Australia. The approval from Chinese Taipei was received on 26 February, a few days before drilling operations began.
Site 1143 is situated in poorly charted waters labeled Dangerous Grounds on the Admiralty charts. Although the site had been surveyed, extra precautions were necessary to ensure that the passage to the site was done in the safest possible manner. The 60-nmi transit across Dangerous Grounds was to be made at reduced speed, only during daylight, and only with calm seas and clear visibility.
Another issue was the piracy threat in the region. The vessel received a warning on 20 February from the Regional Piracy Center (RPC) in Kuala Lumpur via the Singapore Inmarsat C station (Sentosa Island) that the area around Sunda Strait and Karimata Island is the most prone to pirate raids. In response to this alert, the captain decided to adjust the speed of the ship to ensure a daylight transit across the Sunda Strait. The RPC alerted the vessel that persons in military uniforms and using military vessels had recently attacked ships passing close to the location of Site 1143. This information plus data from other sources raised serious questions regarding the security of the vessel during operations at Site 1143. The matter was referred to Ocean Drilling Program (ODP) management, who in turn consulted with senior program officials in Washington, D.C. On 22 February, a request was issued to the director of the Office of Ocean Affairs of the U.S. Department of State to review this matter and to provide advice, procedures, and assurances for the vessel's safety at Site 1143. On 23 February, the captain met briefly with the scientists and technicians and discussed ship security issues, including precautions that would be followed during the transit through the Sunda Strait. Also discussed were procedures to be followed should persons unknown attempt to board the vessel. Although an attack on the vessel was deemed highly unlikely, prudence and diligence required that this issue be addressed before crossing the strait.
At 0600 hr on 25 February, the vessel left the Indian Ocean and entered the Sunda Strait between Java and Sumatra. The ship entered the strait while it was still dark and with heavy rain punctuated by an occasional lightning flash. The eruption of Anak Krakatoa ("son of Krakatoa") was visible through the gloom from a distance of 20 nmi. The vessel passed within 6 nmi of the cone that is now growing in the caldera left by the 1883 eruption.
On the morning of 23 February, the S-band (10 cm) radar failed. During the subsequent trouble shooting by the Overseas Drilling Limited electronic technicians, the problem was ascertained to be in the rotary joint and/or associated cabling located in the antenna assembly. No spares for these items were on the vessel. The approach to Site 1143 required that both X-band and S-band radar units be operational. The vessel was therefore diverted to Singapore at 0830 hr on 26 February to allow factory representatives with the proper parts to work on the defunct unit. The ship arrived at the Changi holding anchorage in Singapore at 1500 hr on 27 February. At 1030 hr on 28 February, two technicians from Aeradion Technology Pte Ltd. and the vessel agent, Victor Chan, boarded the JOIDES Resolution, and the repairs were concluded in less than 2 hr. The vessel was under way to Site 1143 at 1215 hr on 28 February.
As the ship neared Dangerous Grounds, a fax was received on 3 March from the deputy director-general of the State Oceanic Administration of the Peoples' Republic of China in Beijing. This fax provided additional emergency contact phone and fax numbers in Beijing as well as reassurances that the Chinese navy had been instructed "to keep a close eye on the cruise." Because the PRC naval base at Yong-Shu-Jiao ("always summer reef") is located ~20 nmi northwest of Site 1143, this fax furnished the necessary assurances for vessel security that were required before establishing station keeping at Site 1143.
At 0445 hr on 3 March, ~5 nmi from the entry position to Dangerous Grounds, the forepeak tank was filled to adjust vessel trim bow down. This was done so that if the vessel were to ground on a reef, the bow would be the first point of contact. If the bow were to strike a shoal, the forepeak tank would be drained and the vessel backed off and diverted to a safe port for a hull inspection. At 0500 hr the speed was reduced to 6 kt; at 0600 hr, the JOIDES Resolution altered course from 49° to 90° at position 09°20.0´N, 112°5.5´E, and entered poorly charted waters. Lookouts were posted as the vessel made its way to the location that marked the beginning of the 3.5-kHz survey point.
At 1215 hr, a PRC navy patrol vessel, South Tug 156, was sighted. After an initial attempt by our Chinese co-chief to inform the PRC vessel of our identity, no radio communication was established. The patrol craft followed us to the site location. At 1530 hr another vessel, named Truong SA-12, approached the JOIDES Resolution, and the crew attempted to hail us. This ship identified itself as Vietnamese. Our captain was unable to communicate with the Truong SA-12 because of the language barrier.
From 1500 to 1530 hr, a 3.5-kHz survey was conducted over an existing seismic line as the vessel approached the site from the southwest. The survey was aborted earlier than planned as a result of the proximity of the Chinese and Vietnamese vessels and accompanying communication problems. At 1605 hr, after verifying site location with bathymetry, the positioning beacon was dropped on precise Global Positioning System coordinates.
After the hydrophones and thrusters were extended and the vessel located on position, the corrected precision depth recorder depth referenced to the dual elevator stool was obtained and indicated 2782.4 m. The advanced hydraulic piston corer (APC) and extended core barrel (XCB) bottom-hole assembly was made up and deployed. During the tripping of the drill string, the vessels Truong SA-12 and South Tug 156 remained visible until nightfall. At 2200 hr, the South Tug 156 moved away from the site and was lost to radar. The Truong SA-12 lingered in the area and kept us company until the site was abandoned.
Hole 1143A was spudded with the APC at 0330 hr on 4 March. Piston coring advanced to 190.4 mbsf with excellent recovery (102%). The cores were oriented starting with Core 3H. APC refusal resulted when Core 21H did not achieve a full stroke into the indurated sediment. The hole was deepened with the XCB to the depth approved by the PPSP, 400 mbsf. The average recovery for the entire hole was 95% (Tables T1, T2 [both also in ASCII format]). Only a trace amount of methane was measured at concentrations <10 ppmv (see "Organic Geochemistry"). No higher hydrocarbons were detected. Downhole temperature measurements were obtained using the APC temperature tool (APCT) before the retrieval of Cores 4H, 7H, 11H, and 16H, at 31, 60, 98, and 145 mbsf, respectively. A temperature gradient of 84°C/km was calculated from these data (see "Physical Properties").
Three wireline logging runs were planned. After the hole was flushed with a 30-bbl mud treatment, it was displaced with an additional 100 bbl of sepiolite. During the pipe trip to the logging depth of 86 mbsf, the driller did not observe any increased weight caused by a restriction in the size of the hole. The first log was conducted with the triple combination tool suite. Results of the first run determined that the hole was in generally good condition below 210 mbsf and provided satisfactory results below this depth. Above 210 mbsf, there were alternating swelling clays and washouts as large as 45 cm. Several tight spots were measured, and a 3-hr wiper trip was performed before the next tool string could be deployed. Later deployment of the Formation MicroScanner (FMS) and sonic tool combination encountered an obstruction in the hole at <20 m below the bit. Several attempts to pass this obstruction proved fruitless. The mud pumps were used in an attempt to hydraulically push the tool suite past the hole constriction, but this maneuver gained only ~3 m. A moderate overpull was required to free the tool from the mud. After recovering the logging tool, the drill pipe was lowered past the obstruction to a depth of 163 mbsf and then pulled back with the bit positioned at 134 mbsf. The second deployment of the FMS required well over an hour for the logging tool to be worked through the clays. The hole was logged in one pass from 378 to ~158 mbsf. The planned deployment of the geological high-resolution magnetic tool (GHMT) was canceled. The logging equipment was disassembled, and the drill string was pulled clear of the seafloor.
The vessel was offset 20 m east for Hole 1143B. Before coring was begun in this hole, a bottom-water temperature measurement was obtained with the APCT. At 0130 hr on 7 March, Hole 1143B was spudded with the APC. The inferred seafloor depth from the mudline recovery was 2783.5 m. After advancing to 175.4 mbsf, APC refusal resulted when Core 19H did not achieve a full stroke. The hole was deepened with nine XCB cores to 258.2 mbsf, which was considered the target depth for this hole. All piston cores were oriented starting with Core 3H. The bit cleared the seafloor at 0010 hr on 8 March. The average recovery for the hole was 95% (Tables T1, T2).
The vessel was offset 10 m east, and the last hole of the site was spudded with the APC at 0100 hr on 8 March. The seafloor depth calculated from a presumed mudline recovery of 9.4 m was 2784.5 m, but hole-to-hole correlation showed that the top of the core was actually 4 m below the mudline. The hole was APC cored to 177.4 mbsf. The piston cores were oriented starting with Core 3H. The hole was deepened with the XCB to 286 mbsf when approval was received to extend the depth of the hole to 500 mbsf. The XCB coring continued until 2315 hr on 9 March when the last core (54X) was recovered from 500 mbsf. The average recovery for the hole was 96%. The average recovery for the site was 95% (Tables T1, T2).
The drill pipe was pulled out of the hole and cleared the seafloor at 0045 hr on 10 March. As the drill string was being recovered, both primary and backup beacons were retrieved, and the hydrophones and thrusters were retracted. The bit was at the rotary table at 0530 hr, and by 0545 hr the drilling equipment was secured for the voyage to the next site. At 0655 hr, a submarine periscope was clearly visible as it crossed our bow and pursued a reciprocal course that brought it within one-quarter mile of the starboard side of our vessel. The JOIDES Resolution cleared Dangerous Grounds at 1300 hr at 10°0´N, 113°17.1´E.