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doi:10.2204/iodp.proc.329.112.2011

Operations

Ship operations

The KNOX-02RR expedition began in Apia, Samoa, on 18 December 2006 and ended in Dunedin, New Zealand, on 27 January 2007. During the cruise, we surveyed and cored 11 sites in the region of the South Pacific Gyre. Details of the survey, lander, and coring operations are provided in Table T6.

Deck operations

Deployments of towed gear and other underway gear

The Roger Revelle departed Apia, Samoa, on the Julian day 352 of 2006 at 0300 h Universal Time Coordinated, beginning the KNOX-02RR cruise. The cruise schedule involved several transits between sampling locations. At each location, a seismic survey was conducted prior to coring operations. Underway data collection began upon departure from the Samoa Exclusive Economic Zone (EEZ). Data were collected on a continuous basis from the acoustic Doppler current profiler (ADCP), hydrographic Doppler sonar system (HDSS), gravimeter, and the meteorological acquisition system (MAS). The MAS data include the ship’s latitude, longitude, course over ground, speed over ground, speed over water, gyro compass reading, depth in meters, air temperature, barometric pressure, relative humidity, dew point, relative wind speed and direction, true wind speed and direction, and salinity (psu). Transits outside of any EEZ included data collection with the multibeam EM12, Knudsen 320 B/R echo sounder, and Marine Magnetics SeaSpy magnetometer. Time and location of data acquisition are detailed below. Losses of data for 1 h or less caused by equipment malfunctions are not documented.

Logging of continuous and transit data began upon departure from the EEZ on Julian day 354 at 0615 h (16645.77°W, 2157.11°S). The magnetometer was retrieved for the beginning of the first seismic survey on Julian day 354 at 1700 h (16552.44°W, 2354.341°S). The magnetometer was redeployed and logging of all transit data commenced on Julian day 356 at 0425 h (16535.04°W, 2351.71°S).

The magnetometer was retrieved for maintenance at 1633 on Julian day 356 (16306.884°W, 2430.642°S) and redeployed at 0000 h on Julian day 357 (16142.39°W, 2451.32°S).

The magnetometer was stopped for a seismic survey on Julian day 357 at 2244 h (15710.97°W, 2557.34°S). The multibeam and echo sounder were secured on Julian day 358 at 0823 h (15653.67°W, 2603.09°S). The magnetometer was redeployed for logging on Julian day 359 at 0524 h (15628.40°W, 2607.97°S). The multibeam and echo sounder recommenced logging on the same day at 0619 h (15616.49°W, 2610.97°S).

The magnetometer was stopped for a seismic survey on Julian day 360 at 2005 h (14831.34°W, 2751.47°S). The multibeam and Knudsen echo sounder were secured on Julian day 361 at 0244 h (14835.47°W, 2756.56°S) and returned to logging on Julian day 362 at 0010 h (14835.35°W, 2756.87°S).

All underway logging was stopped for the Cook Islands EEZ on Julian day 362 at 0237 h (14807.23°W, 2752.84°S). The magnetometer was redeployed and all underway logging recommenced on Julian day 363 at 1139 h (14044.43°W, 2652.52°S).

The magnetometer was stopped for seismic survey on Julian day 365 at 0206 h (13754.21°W, 2627.21°S). The multibeam was secured on Julian day 364 at 0725 h (13756.42°W, 2628.96°S). The magnetometer, echo sounder, and multibeam recommenced logging on Julian day 365 at 0250 h (13750.87°W, 2630.97°S).

The magnetometer was retrieved for seismic survey and stopped logging on Julian day 001 at 1015 h (13128.00°W, 2826.88°S). The multibeam and echo sounder were secured on the same day at 1615 h (13123.661°W, 2825.242°S). The multibeam and echo sounder recommenced logging on Julian day 002 at 1144 h (13122.716°W, 2826.13°S), and the magnetometer was redeployed and logging on the same day at 1215 h (13118.11°W, 2826.34°S).

The magnetometer was retrieved for seismic survey and stopped logging on Julian day 004 at 0339 h (12256.89°W, 2753.751°S). The multibeam and echo sounder were secured on the same day at 1127 h (12312.86°W, 2754.87°S). The multibeam and echo sounder resumed logging on Julian day 005 at 0732 h (12308.31°W, 2754.99°S). The magnetometer was redeployed and logging on same day at 0754 h (12303.42°W, 2754.97°S) but data are not available from 1845 to 2113 h due to error.

The magnetometer was retrieved for seismic survey and stopped logging on Julian day 006 at 0715 (11750.28°W, 2754.01°S). The multibeam and echo sounder were secured on the same day at 1516 (11737.28°W, 2744.51°S). The multibeam and echo sounder logging recommenced on Julian day 007 at 1118 (11737.78°W, 2744.88°S). The magnetometer was redeployed and logging same day at 1136 (11730.94°W, 2747.08°S).

The magnetometer was retrieved for seismic survey and stopped logging on Julian day 010 at 2258 (13305.41°W, 3803.63°S). The multibeam and echo sounder were secured on Julian day 011 at 0642 (13305.49°W, 3803.68°S). The magnetometer was redeployed and logging on Julian day 012 at 0555 (13307.44°W, 3802.90°S). The multibeam and echo sounder logging recommenced on the same day at 0605 at same location.

The magnetometer was retrieved for seismic survey and stopped logging on Julian day 013 at 0811 (13920.98°W, 3910.63°S). The multibeam and echo sounder were secured on the same day at 1855 (13948.03°W, 3918.617°S). The multibeam and echo sounder logging recommenced on Julian day 014 at 2143 (13944.43°W, 3918.12°S) and the magnetometer was redeployed same day at 2208 (13952.41°W, 3919.08°S).

The magnetometer was not responding, and logging was secured on Julian day 14 at 2315 (14010.45°W, 3923.28°S). The problem was solved, and logging recommenced on Julian day 15 1116 (14308.811°W, 4000.161°S).

The magnetometer was retrieved for seismic survey and stopped logging on Julian day 017 at 0053 (15280.48°W, 4156.09°S). The echo sounder and multibeam were secured on the same day 0804 (15302.98°W, 4148.95°S). The multibeam and echo sounder logging recommenced on Julian day 018 at 0617 (15306.71°W, 4150.70°S), and magnetometer was redeployed and logging at 0654 (15316.106°W, 4155.33°S).

The magnetometer was retrieved for seismic survey and stopped logging on Julian day 020 at 0445 (16257.62°W, 4559.84°S), and the echo sounder and multibeam were secured at 1326 (16311.05°W, 4557.85°S). Magnetometer logging recommended at 1208 on Julian day 21 (16315.11°W, 4557.82°S), while echo sounder and multibeam recommenced on the same day at 1214 (16316.23°W, 4557.81°S).

Permission was granted to record data inside the New Zealand EEZ. New data files were started on Julian day 022 at 2300 (17102.23°W, 4553.58°S). The magnetometer was retrieved and stowed on Julian day 25 at 0445 (17713.86°E, 4547.15°S). We stopped multibeam logging on the same day at 1900 (17431.17°E, 4546.11°S) and stopped the echo sounder at 2000 (17421.58°E, 4545.58°S), marking the end of data logging for KNOX-02RR.

Coring operations

Additional information on coring operations is presented in Table T6.

At Site SPG-1, we deployed, in order, a 10 ft benthos gravity corer (2.5 inch), a 30 ft piston corer with no pigs, and a 10 ft trigger corer with seven lead rings, a multicorer, the Scripps CTD, and a 30 ft piston corer with no pigs and a 10 ft trigger corer. The second piston corer had four thermistors.

At Site SPG-2, we deployed a multicorer before moving away from the coring station to deploy the MPI lander. The lander’s ballast weights were lost during deployment. Consequently, the lander did not sink. Its mast was broken while floating, and immediate recovery was initiated. We returned to the coring station to deploy, in order, a 30 ft piston corer with no pigs and a 10 ft trigger corer, the Scripps CTD, and a second 30 ft piston corer with no pigs and a 10 ft trigger corer. The second piston core had three thermistors.

At Site SPG-3, deployed a benthos gravity core (2.5 inch) and the multicorer before moving away from the coring station to deploy the MPI lander. We then returned to the coring station to deploy a 20 ft piston core with four thermistors and a 10 ft trigger core. The cutting shoe of the piston corer was deformed by impact with basalt at the base of the sediment column. We then deployed, in order, the CTD and a second 20 ft piston corer with four thermistors and a 10 ft trigger corer. The cutting shoe of this piston corer was also deformed. The cutting shoe and core catcher were lost from the trigger core, and the cutting shoe rivets were sheared off. We then recovered the lander and began the transit to Site SPG-4 (IODP Site U1367).

At Site SPG-4, we deployed, in order, the multicorer, a benthos gravity corer (2.5 inch), a 30 ft piston corer with a 10 ft trigger corer, the CTD, and a second 30 ft piston corer with a 10 ft trigger corer with seven lead rings.

At Site SPG-5, we deployed a benthos gravity corer (2.5 inch) and then moved away from the coring site to deploy the MPI lander. We returned to the coring station to deploy a 30 ft piston corer with a 10 ft trigger corer with eight lead rings. We recovered the lander, after which we returned to the coring station to deploy, in order, a multicorer, the CTD, and a 30 ft piston corer with four thermistors and a 10 ft trigger corer with eight lead rings.

At Site SPG-6, we deployed a benthos gravity corer (2.5 inch.), found the recovered core unsatisfactorily short, and moved the station. We deployed a second benthos gravity corer (2.5 inch), which recovered nearly the same amount of sediment as the first core, the CTD, a 20 ft piston corer with no pigs and a 10 ft trigger corer with eight lead rings, a multicorer, and a 20 ft piston corer with four thermistors and a 10 ft trigger corer. Because of the stiffness of the sediment, this second piston corer had two pigs in the core bomb.

At Site SPG-7, we deployed a benthos gravity core (2.5 inch) and moved away from the coring station to deploy the MPI lander. We returned to the coring station and deployed, in order, a multicorer and a 20 ft piston corer with no pigs, four thermistors, and a 10 ft trigger corer. The piston corer struck basement and bent the core sheath. After retrieval, the piston corer was disassembled to retrieve the core liner and core. We deployed the CTD and a trigger gravity corer (4 inch), after which we recovered the lander. After lander recovery, we returned to the coring station to deploy a jumbo gravity corer (4 inch) with no pigs.

There were no coring operations at Site SPG-8. It was not on the final cruise track because there was not enough time to survey all 12 sites.

At Site SPG-9, we deployed a benthos gravity corer (2.5 inch), a multicorer, a 20 ft piston corer with no pigs and a 10 ft trigger corer, the CTD, and a 20 ft piston corer with four thermistors, no pigs, and a 10 ft trigger corer.

At Site SPG-10, we deployed a multicorer and then moved away from the coring station to deploy the MPI lander. We returned to the coring station to deploy a 20 ft piston corer with no pigs and a 10 ft trigger corer with nine lead rings. This piston corer was lost at the seafloor; there was no pullout tension and the wireline parted immediately below the trigger arm book clamp. The cutting shoe of the trigger corer was severely cut and torn; the indentations in the cutting edge of the shoe are sharp-edged and square, as if the shoe was slammed against the squared edge of a metal plate several times. Despite the damage to this cutting shoe and the loss of the piston corer, an intact core was recovered from the trigger corer. After this loss, we deployed, in order, the CTD and a 20 ft piston corer with no pigs and a 10 ft trigger corer with nine lead rings. We recovered the lander, after which we deployed a 20 ft piston corer with no pigs, three thermistors, and a 10 ft trigger corer with nine lead rings.

At Site SPG-11, we deployed, in order, a benthos gravity corer (2.5 inch) and a 20 ft piston corer with no pigs and a 10 ft trigger corer with 10 lead rings. As at Site SPG-10, the piston corer was lost at the seafloor; again there was no pullout tension and the wireline parted at the base of the trigger arm book clamp. We deployed, in order, the CTD, a multicorer, a 15 ft trigger gravity corer (4 inch) with 10 lead rings, and a second 15 ft trigger gravity corer (4 inch) with 10 lead rings.

At Site SPG-12, we deployed, in order, a 15 ft trigger gravity corer (4 inch) with 10 lead rings and a multicorer. Sea state was relatively high. During multicorer deployment, a tag line caught on a corer leg and was cut at ship’s rail. One tube closed before the multicorer left the surface. The multicorer returned with almost no sediment. We deployed a 15 ft trigger gravity corer (4 inch) with 10 lead rings, CTD, a 20 ft trigger gravity corer (4 inch) with 10 lead rings, and a 20 ft trigger gravity corer (4 inch) with 10 lead rings before leaving the station for our transit to Dunedin, New Zealand.

Lander operations

Lander deployments and operations are described in Table T7.

Concentration/temperature/depth recorder operations

At all 11 sites surveyed, a CTD Rosette with twenty-four 2.5 L Niskin bottles took water from three to five depths. Recorded data at all sites included temperature, pressure, salinity, conductivity, and fluorescence. Location, date, time, and depth data are presented in Table T8.

A list of subsamples taken from the CTD casts is presented in Table T9.

Argo float deployment

Twelve Argo floats were deployed during Cruise KNOX-02RR. These floats were deployed in support of the worldwide network of Argo floats (www.argo.net). This organization has the goal of deploying 3000 floats by the end of 2007 with a spacing of approximately 3° in the world ocean. These floats autonomously collect pressure, temperature, and salinity data in vertical profiles (~200 data points per profile) taken on a 10 day cycle (Fig. F6). Each float is designed to operate for ~4–5 y. These data will be used to quantify changes in the oceanic heat and freshwater budgets and transport. The data will be used to initialize coupled ocean-atmosphere models.

The floats were deployed by lowering by hand with a tag line from the starboard quarter while the ship was under way at 6–12 kt. The release mechanism was activated upon contact with the water and the tag line, nylon straps, and release mechanism were recovered.

Table T10 contains information regarding the time and location that the Argo floats were deployed. The first three floats are ballasted to 1450 db and the remaining nine to 1600 db. The data from these floats can be found at sio-argo.ucsd.edu/table.html.

Core recoveries and distributions

Cores and core flow for recovered piston, trigger, and gravity cores are shown in Table T11. Details of the subsampling and curation of the cores are given in a separate file. Figures F7 and F8 provide a graphic illustration of core recovery for each site (this figure provides multicore recovery for only the first multicore at each site). Recovery and distribution of samples from the multicorers are given in a separate file.

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