LAB ACTIVITIES

Following in the footsteps of Leg 175, a record-breaking core recovery leg, Leg 176 was a record breaking hard-rock recovery leg. It was a beautiful sight to see 9.5 m of hard rock, core after core, but it put our procedures for handling hard rock to a test. Hard-rock curation had evolved from years of obtaining far less material per leg and, as a result, required procedures that were too time consuming for the amount of core we collected this leg. At the beginning of the leg, the co-chief scientists divided the scientists into three groups: igneous petrologists, metamorphic petrologists, and structural geologists. Each group worked a shift in the lab, leaving a 6-hr period at night when no scientists were working in the lab. This required that a core be in the lab for at least 18 hr. With cores coming up at approximately 3-hr intervals, the dilemma was obvious. The co-chiefs also decided to delay all personal sampling until the end of the leg, thereby requiring all the working halves to be brought back to the lab. This plan benefitted the scientists immensely because there were absolutely no disagreements between shifts as is common on legs where scientists cover the lab 24 hr per day with two shifts. Also, before any personal samples were taken, all the material had been recovered. From a core-flow perspective, this plan only worked for two reasons. First, bit changes were required at 3-day intervals, thereby providing a break where the lab could get caught up. Second, the drill string broke off in the hole, ending the coring a week early. If coring had proceeded normally until the end of the leg, there would not have been enough time to process all the personal samples and attend to normal end of the leg cleanup, reports, and organization, especially for the curatorial staff. As stated in the Leg 175 Lab Officer's report, record-breaking legs stress our technical staff to an unacceptable limit. The same can be said for this leg with the amount of hard rock recovered and the procedures imposed for handling the material. As an example, the technical staff glued approximately 15,000 hard-rock labels on pieces of rock, a very time-consuming and tedious task. Another example was the multiple handling of core boxes from the core lab to the reefer. The working sections were actually handled three times this leg: first to store them, second to bring them back to mark the samples, and third to cut the samples. Core lab manpower was limited during the night shift primarily because the thin sections and X-ray fluorescence samples required the full-time attention of three technicians. The overall result was that the scientists were able to work harmoniously at the expense of the technical staff, who came seriously close to having interpersonal conflicts get out of hand.

Chemistry Lab
X-ray fluorescence samples were analyzed for carbon, nitrogen, hydrogen, and sulfur (CNHS). Only one chemistry technician sailed this leg, and most of her time was spent helping with curation in the core lab. A chemistry instrument service tracking system was developed using FileMaker Pro.

Computer Services
Support for the increasingly complex shipboard computer system now requires two system managers and one programmer for JANUS support. With the exception of network crashes, the system was quite stable. Most of the time, allocation went to assisting scientists, technicians, and Sedco personnel with hardware and software problems, most falling into the category of user training. One of the system managers was new and overlapped 6 hr with the other system manager for training. The JANUS programmer covered the system for the other 6-hr period. Special projects included:

• The fiber optic network Cabletron equipment installation.
• Set up and testing the new server for the imaging system.
• Installing one of the new janusaxp servers.
• Testing the Ffastest high speed data (HSD) system on the SeaNet system. It worked fine. Procedures need to be determined for its use as an e-mail transfer system on future legs.

The special conditions and requirements of hard-rock operations brought to light an unexpected variety of software operation and design issues primarily concerning JANUS&151data;upload and data acquisition. The problems were resolved for the most part, but it called to attention the need for a JANUS programmer to sail on upcoming legs.

Core Lab
Lab procedures were modified significantly from the normal for this leg. After initial unsuccessful attempts to use core liners, all cores were drilled without a core liner. Because the quality of the core was good, this actually simplified our handling of the core, except that all the core had to be scrubbed with a brush to remove rust and dirt from the barrel. The core was video scanned (DMT Color CoreScan) and run through the multisensor track before being cut into working and archive sections. Paleomagnetic measurements, photography, and thermal conductivity measurements were done with the archive section. The scientists used the working half for descriptions, samples, and physical properties measurements. All personal samples were taken after the drill pipe broke off in the hole and coring operations ceased.

Curation
This was an unusually demanding leg for the shipboard curator and assistant curator because of the stringent guidelines and policies governing hard-rock curation and sampling. With normal hard rock recovery these policies are reasonable, but the shear quantity of hard rock recovered made curation a tedious task. Because of the curatorial complexities, future hard-rock legs should read and take to heart the curatorial report from this leg. Cores from Leg 118 were shipped to Cape Town and studied on the transit to Hole 735B.

Downhole Measurements Lab
The Davis-Villinger temperature probe was tested in anticipation of needing an open hole temperature measurement. Because of hole problems the tool was not deployed.

Paleomagnetics Lab
The regularly scheduled technician was unable to make it to Cape Town to participate on this leg. The three scientists, however, had all sailed previously, and one of our computer techs was a former magnetics tech. Despite initial disappointment that the new cryomag's dynamic range was lacking on the higher end, a tremendous amount of data was acquired from the split sections and minicore samples.

Photography Lab and Microscope Services
Routine operations with no special projects or problems to report.

Physical Properties Lab
All whole-round sections of hard rock were measured on the multisensor track using the gamma ray attenuation porosity evaluator (GRAPE) sensor, magnetic susceptibility sensor, and natural gamma sensor. Minicore samples were used for index properties and velocity measurements. Pieces from the archive section were used for thermal conductivity measurements. Resistivity was attempted but abandoned, because the values were not consistent.

Thin Section Lab
Making thin sections was a full-time effort for one technician. The coarse-grained gabbros often required oversized billets and sections.

Underway Geophysics and Fantail
The scientific plan did not require seismic surveys, but a VSP experiment required rigging and hanging a 1000-cubic-inch air gun and 400-cubic-inch water gun over the side using crane #3. An air-powered winch wrapped with a fuzz-fairing hydrophone cable was welded to the top of the welder's shack. The hydrophone was deployed during the VSP to a depth of 300 m. Bathymetry and magnetics were collected during the first transit. Navigation was continuously recorded during the leg. The equipment spare parts were relocated into new cabinets, and the area behind the equipment racks was cleaned out to make a safer and more efficient work space.

X-ray Lab
Preparing and analyzing samples took the full-time attention of two technicians, one for sample preparation and one to run the X-ray fluorescence equipment. Samples were prepared for both major and trace elements. The X-ray diffraction unit received limited use.

Electronic Services
Electronics maintenance required the support of two technicians to keep the lab equipment functioning on a 24-hr basis. In addition to routine maintenance and troubleshooting, the electronics techs installed a Quorum weather satellite system on the bridge, a weatherproof box on the Schlumberger maxi cab to plug guns, blast phones cables for VSP experiments, assisted in the installation of an EPC recorder for seismic display, and updated the lab stack electrical line drawings.

Safety
Four members of the technical staff participated on the marine emergency technical squad (METS). The team participated in all Sedco fire drills and staged a chemical spill in the lab stack for one of the drills.


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