Shipboard analysis of interstitial-water samples on Leg 168 included refractometric analysis for salinity; titrations for pH, alkalinity, chloride, calcium, and magnesium; ion chromatography for sulfate, potassium, sodium, calcium, and magnesium; and colorimetric analyses for silica, phosphate, ammonium, and boron. Atomic absorption spectrophotometry was used to quantify low concentrations of magnesium in pore waters. The boron determination was hampered by a specialty chemical that did not dissolve properly.
Six hundred "osmosis" samples were analyzed for anions and cations on the Dionex. The samples originated from four OsmoSamplers that were deployed with the CORKs. The analyses will be used to help the scientists determine the changes in composition of the input fluid and its rate of diffusion in the sampler over time as it sits in a CORK.
Sediment core samples were analyzed for inorganic and total carbon, using the coulometer and the CNS. Based on their organic carbon content, some samples were selected and analyzed with the RockEval. The system was used to determine S1, S2, S3, and S4. Carbon dioxide and structural water were determined on selected rock samples using the CNS.
Gas chromatograph 3 was used during this leg to provide real-time monitoring of the volatile hydrocarbons.
Although Leg 168 was not a high-recovery leg, computer use was fairly heavy, as usual when members of the science party have the luxury of time for data analysis. It is worth noting that more than an average number of PC users sailed this leg, as well as several avid UNIX users. The large number of sites we drilled gave us a good opportunity to test the post-stabilization period build of the JANUS database with all OPERATIONS and CORELOG data entered.
The SUN operating system was upgraded to Solaris 2.5 and the UNIX environment was standardized to mirror the shore systems. Installation of additional and upgraded software on the SUN stations was performed including back-up software, a graphic exchange facilitator and tools to manage users and printers from a interface on the system manager's SUN and to conserve disk space. An alternate boot disk was also built to allow quick failure recovery.
Several PC viruses were brought aboard. The first one was troublesome just from the standpoint of trying to figure out what was occurring. Virus detection software was then used regularly, which located and removed two more.
A scheduled power outage (for maintenance) during the San Francisco port call apparently precipitated a number of equipment failures, including two power supplies for Black Box media convertors in the Underway Lab and a 1.3-Gb drive (DATBAK on DEWEY).
The FDDI optical cable project is currently on hold. The electronics staff had a full schedule this leg and no time was available for this major effort. The project is presently planned to be completed on a "time-available basis." The cable ways were surveyed this leg to determine if there is space in the cable ways, available bulkhead penetration openings, and sufficient curve radii are present to accommodate the cable. Deficiencies were noted that could hamper installation when it is started. The information from this survey was given to the system manager.
The core lab was returned to its usual core flow configuration while proceeding to the leg's drill sites. The core drills and sample cutting saws were returned to the aft bench. The core entry bench was cleared to accommodate the tools used to take biological samples.
Sediment and basalt basement cores were recovered on Leg 168. The fact that these cores were not drilled in sequential order will make racking the cores in the repository somewhat more tedious. Special care was taken to ensure that the core box inventory sheets were as easy to follow as possible.
The recovered cores will be transported by truck in a refrigerated container to the Gulf Coast Repository. There was one frozen shipment to Stockholm and two shipments were packed with blue ice to go to Santa Cruz and the Pacific Science Center at Vancouver, BC. One set of refrigerated samples was to be picked up and hand carried from the Victoria port call.
The Second Look Lab was cleared of several old and obsolete instruments that were returned to ODP. The lab was set up for resampling cores when necessary. Testing continued on the JANUS database and developmental work continued on the design of a new bin plan for the sample table and a better shipping container for whole-round samples.
Downhole Measurements Lab
Determining the heat-flow characteristics of the area was a major science goal. The measurements were made using the APC Adara tool and the DVTP. In situ temperature measurements were taken 93 times with a 100% success rate. The WSTP pore-water sampler was used twice as an open-hole borehole-water sampler, collecting basement-water samples. It was deployed with the APC/Adara cutting shoe. Any abnormalities in data were the result of formation hardness, drilling problems, leaking thermistors (WSTP), or (possibly) poor instrument calibration (Adara tool 19).
Testing the new cryogenic magnetometer and its software began immediately. The instrument's noise level is low and so far no activity or sea state has had any noticeable effect on the noise level or the liquid helium boil off; the baffles and other improvements have worked well. It is estimated that the next fill will be in 3 years using our current average boil off. Whole-core pass through capability was restored. A Labview version of the cryogenic magnetometer positioning software was written to replace the problematic software that came with the instrument. No data reduction capabilities were provided.
Routine paleomagnetics tests on Leg 168 were pass-through and discrete measurements for magnetostratigraphy, characterization of magnetic carriers using the pulse magnetizer, and discrete susceptibility measurements and use of the Kappabridge on the basalts.
Aluminum Unistrut framing, which is used to support shelving, was installed around the new cryogenic magnetometer to potentially reduce magnetic fields near the instrument. The capacitors in the GSD-1 demagnetizer were replaced and that instrument was recalibrated.
There were few paleontology people this leg, so one of the benches was used by the chemists. One of the centrifuges failed to start; we were unable to locate the schematic that was ordered. One damaged microscope objective was returned for repair.
The state of the chairs in the microscope lab was surveyed and recommendations for new chairs were made. The back support on many is getting weak and the availability of modern mechanisms to easily change seating heights prompted the review.
While core processing and photography were routine this leg, there were several other photography assignments. Color photographic slides were taken of the labs, equipment, and the CORKs and casing strings. The lab photos of equipment are for the World Wide Web home pages being developed onshore.
Physical Properties Lab
The regular routine of physical properties measurements was performed on the recovered cores and discrete samples were taken. Measurements includes MST, thermal conductivity, Velocity Shear Resistivity (VSR), and index properties.
Thermal conductivity measurements included testing the new Teka thermal conductivity system. The system's half-space probes seem to be working well and the full-space probes are being tested.
Special projects in the lab included writing control software for the new cryogenic magnetometer in Labview and adding a plotting routine to the MST Process Control screen. The new Moisture and Density (MAD) system was tested. The weighing function did not work correctly. The source code, written in Labview 4.0, was not available.
There was a problem with the balance station that supports the index properties measurements that resulted in using the new sensors from the MAD system. The NB2000 board was installed in a Macintosh IIci to run the balance program. The old sensors' insidious problem resulted in small errors that were not apparent until the data were processed. The cores were resampled to replace the lost data. The faulty sensors were sent to ODP for repair and recalibration. It is suggested that they be returned to the ship as spares.
A drift in the pycnometer values, ±0.2-0.3 g/cm3, was traced to a nearly empty (500 psi) helium gas bottle. This was changed and the O-rings replaced, which corrected the problem.
The Thermcon box malfunctioned, resulting in the electronics technicians calibrating the box and needles. The results are being evaluated.
Thin Section Lab
Approximately 63 thin sections were requested. Billets from the last site were taken by the investigators to prepare thin sections at their home institutions. Altered basalt with vesicles and clay was a challenge to work with, requiring epoxy impregnation and occasional duplication.
During Leg 168, approximately 700 samples were analyzed by X-ray diffraction. Quantitative analysis was done on most of these samples. MacDiff software was used to calculate peak areas for seven mineral phases and export the results to a spreadsheet. Andy Fisher's revised Pfactor program was then used to derive factors used to determine the percentage of each of the seven minerals in a sample. With the MacDiff software and now the Pfactor program, it is possible to easily, efficiently, and routinely process large numbers of XRD files onboard for quantitative analysis (e.g., Legs 164, 166, and 168).
Twenty-nine basalt samples were analyzed by X-ray fluorescence (XRF) for the usual suite of 10 major element oxides. Because of the chemistry of the new flux (VI), it was necessary to make a set of 14 standard beads for this calibration at a 6:1 flux:standard ratio. Although the standards were weighed on board, the coefficient correlation was excellent and the resulting data were of high quality until near the end of the cruise when goniometer Gonio 2 became unstable again. Problems with the XRF instrument were not resolved in time to do a calibration for trace-element analyses.
With the new flux (VI), it was not possible to make successful bead samples with the previously used 12:1 ratio. The necessacity of using the 6:1 flux:standard ratio resulted in using twice as much sample and some rare standards. The initial change in fluxes lowered the fusing temperature, which created a "less fluffy" physical characteristic that is harder to weigh. Another flux (VII) with a different chemistry was ordered and should have arrived for Leg 169. Some of the initial comparison tests were attempted with the Claisse fluxer, but there were problems with flame stability achieving the fusing temperatures. The NT-2100 bead sampler performed very satisfactorily. The cooling water for it was plumbed to run directly into the eye wash drain.
There were major problems with both goniometers in the XRF instrument. Gonio 1 was not operational. Gonio 2 was operational, but it was not stable over time. When more time became available to work on the unit at the end of the leg, most of the problems were resolved. A service call was scheduled in Victoria to verify the condition of the instrument.
Air quality forms were passed out to the science and technical staff to be completed for the use of the Health and Safety Department at Texas A&M University. There have been instances of cruise participants' allergies being aggravated at sea, and this is a step toward systematically investigating these occurrences.
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