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IODP Expedition 336:
Mid-Atlantic Ridge Microbiology
Week 4 Report (9-15 October 2011)
PDF file is available for download.
Science Results
After finishing drilling operations in the 210-m deep Hole
1382A with repeated wiper trips, an 18-hour logging program was conducted. The
first tool string comprised the DEBI-t laser-induced fluorescence probe, density/caliper,
total gamma ray, temperature, and resistivity tools. Upon completion of the
first pass, a power outage occurred and the tool was brought up. Next, a second
tool string with the spectral natural gamma ray sonde
and the formation microscanner (FMS) was lowered and
run down and up the hole twice. The FMS data show variable borehole caliper
between 145 and 168 m depth below seafloor. The full logging data are currently
being processed.
A packer hydrologic test was carried out next, but the
packer did not seal for more than 10 minutes (due to ship heave up to 3 m) and
the test was abandoned after four attempts. Following these operations a visual
inspection of the Hole 395A re-entry cone and ROV landing platform was
performed in order to assess the position and integrity
of the landing platform in anticipation of future operations.
We also successfully installed a CORK observatory in Hole
1382A. This 210-m deep hole is equipped with an instrument string comprising six
osmotic pump-driven samplers for basement fluids and microorganisms as well as enrichment
experiments, an oxygen probe with data recorder, and temperature sensors. The
samplers and probe are installed in an interval from 152 to 174 mbsf. A
pressure gauge and fast-pumping osmosamplers are situated in the wellhead and monitor/sample fluids at 161 m depth below seafloor.
Sampling of core material for shipboard studies included cutting
of thin section billets, quarter-round core for bulk rock chemistry and XRD
work, cubes for physical property measurements, and microbiology. Microbiological sampling took place first in the core splitting room prior to other sampling. Two
to six samples were selected based on lithology and alteration and were
processed in the microbiology/chemistry lab for DNA/RNA, cultivations,
microscopy, spectroscopy and biogeochemical assays. The shipboard petrologists then divided the recovered core into 8 major lithologic units, comprising up to 17 subunits. Major unit
boundaries are defined by contacts between massive and pillowed flow and
interlayered sedimentary units. Each major lava flow units consists of several
cooling units, which are recognized by glassy or variolitic
margins and/or marked changes in grain size. Initial results from thin section
studies reveal a large range of grain size ranging from glassy to medium-grained
and textures (aphanitic to subophitic
or intersertal). Basalts are either aphyric or plagioclase-olivine phyric
and have <3% vesicles. Phenocryst contents
range up to 25%, with plagioclase being more abundant than olivine. The extent
of alteration ranges up to 20%, with clay (smectite, nontronite, celadonite) being the
most abundant secondary phase, followed by Fe-oxyhydroxides
and zeolites. The sedimentary unit in Cores 8R and 9R feature a variety of clasts, including plutonic and mantle rocks. The peridotites are weakly serpentinitzed harzburgites and lherzolites
with a protogranular texture. Intensity of
deformation of the gabbroic lithologies ranges from undeformed to mylonitic. Minor cataclastic deformation of the peridotites
has led to the development of carbonate-filled vein networks, along which the
rocks have been subjected to oxidative alteration, resulting in the breakdown
of olivine to clay, oxide, and carbonate. Sampling for physical properties has
been conducted to cover the range of lithologies as
well as potassium and uranium concentrations identified during natural gamma-ray core scanning.
Operations
Week 4 began
while tripping out of the Hole U1382A after reaching 210.0 mbsf. After the bit
was back on the rig floor and before starting logging, we assembled a stand of
6.75 inch perforated and coated drill collars for the lowermost portion of the
CORK installation. We wanted to do this sufficiently prior to assembling the CORK
as we painted it with an epoxy paint that needed to dry prior it being deployed.
Next, we assembled a logging BHA with a logging bit and the drill string packer,
lowered it 50 m into Hole U1382A, and began deploying the logging tools.
Logging proceeded with a modified triple combo string with the DEBI-t tool on
the bottom of the string. Log data were collected while lowering it to the bottom
of the hole. However, while logging upward, the power failed approximately 20 m
below the casing. The tool string was pulled to surface and the problem was
found to be in the cable head. The cable head was re-terminated and we decided
to run the FMS-Sonic tool string next. After 2 successful passes, the lower
portion of the FMS (calipers) would not enter the logging bit. After two hours
of working the string up and down, opening and closing the calipers, and pumping
seawater, the entire tool string finally was able to pass through the logging
bit. We then spaced out the drill string for the hydrologic (packer) flow test
and we started attempts to inflate the packer. We made four attempts to set the
packer inside the 10.75-inch casing, however, each time high vessel heave (3 m)
caused the packer to deflate – so the experiment was cancelled. Before
pulling out of the hole, we lowered the logging bit to the bottom of the hole
to check that the hole was still open to full depth prior to installing the CORK.
We did not encounter any problem intervals and only ~1.5 m of fill. The drill
string was recovered and the bit back onboard at 1328 hours on 10 October. Before
we could begin our next operation we had to slip and cut 115' of drill line. We
started assembling the CORK at 1500 hours on 10 October.
The pre-assembled
6.75 inch perforated drill collar stand was picked up and run through the rotary
table. A crossover to the 5.5 inch perforated casing was installed, followed by
15.35 m of 5.5 inch perforated casing. Miniscreens
were attached to the outside of the lowermost perforated 5.5 inch
casing joint. Crossovers to the 4.5 inch fiberglass casing
were installed and then 44.25 m of 4.5 inch fiberglass casing were made up. Umbilicals from the mini-screens and centralizer/protectors
were installed on the outside of the casing as it was run. Next to be installed
was a crossover to the landing seat for the instrument string, followed by a
crossover to the mandrel containing the swellable and
inflatable packers. Umbilicals were terminated and
connected to the bottom of the combination packer tool and terminated and
connected to the top of the combination packer tool. From there ~91.01 m of 4.5
inch steel casing were run, followed by the CORK head. All pressure and sampling
lines from were connected to the bottom of the CORK. It took us 10 hr to assemble the complete CORK assembly and the bottom of
the CORK string extends to 188.7 mbsf.
Our next step
was to assemble and install the OsmoSampler string
into the CORK at the rig floor. Modification had to be made to the top plug so
it would latch into the CORK head – however these likely did not work. This
operation was completed in 3.5 hr. The camera system was then test fit over the
CORK and at 0630 hours on 11 October, we began lowering the CORK package to the
seafloor. The camera system was installed and Hole U1382A was re-entered for
the last time at 1630 hours on 11 October.
After carefully
lowering the CORK into the hole, we landed the CORK at 1820 on 11 October. The
packer was then inflated to 1200 psi and the camera was pulled to surface. Next
the ROV platform was assembled and rigged up with the ROV deployment tool attached
below the camera system and it was lowered back to the CORK on the seafloor. The
platform was released over the CORK at 0055 hours on 12 October. The camera
system was retrieved and after removing the ROV deployment system, it was
lowered back to bottom to observe the final step of installing the Hole U1382A
CORK observatory – the release of the CORK running tool from the CORK. This
was successfully released at 0425 hours on 12 October. The drill string with
the CORK running tool was recovered back onboard at 1145 ending Hole U1382A.
Our next objective was to install a multi-level CORK observatory
to perform long-term coupled microbiological, biogeochemical, and
hydrological experiments in deeper portions of the oceanic crust at Site U1383
(NP-2). Our first step was to use an 18.5 inch
tri-cone drill bit to perform a jet-in test to determine the length of 20 inch
casing to install with the reentry cone. While we assembled this bottom-hole
assembly and lowered to the seafloor, we retrieved the seafloor beacon used for
Hole 395A and transited (~5.8 km) to Site U1383 in dynamic positioning mode. After arriving at Site U1383, we dropped a positioning beacon at 1812 on 12
October.The jet-in test began at 2240 on 12 October and reached 36 mbsf at 0200 hours on 13 October. The penetration rate
during the last two meters was very slow. The 18.5 inch
bit was back on board at 0930 hours ending Hole U1383A.
Based on the
jet-in test, we decided to run 34.84 m of 20 inch casing for Hole U1383B. The
casing and re-entry cone were run to bottom but our initial attempt managed to
jet the casing in only to 29 mbsf. After trying to advance the casing for over
3 hours with no progress, we pulled the string out of the seafloor and moved 50
m to the northeast. We started our second attempt to start Hole U1383B at 0810
hours on 14 October. This time, we were able to fully land the re-entry system
and casing at 1015 hours. We released the running tool at 1035 hours and
retrieved the drill string with the bit arriving on the rig floor at 1915
hours.
Our next job
was to drill an 18.5 inch hole into uppermost basement
for the 16 inch casing. After laying out both drill collar pup joints and the
casing running tool, the 18.5 inch bit was removed, the nozzles changed and the
BHA was made up and run back to bottom. During the trip into the hole, we had
to pause to slip and cut 115' of drill line and to start lowering the camera
system for reentry. We reentered Hole U1383B at 0518 hours on 15 October, began
drilling at 0704, and encountered basement at 0723 at a depth of 53 mbsf.Drilling continued at a penetration rate of ~2 m/hr
to 68 mbsf. We chose this depth to allow ~9 m of rat hole for the 16 inch
casing. After reaching 68 mbsf, the hole was reamed and conditioned.
Education and Outreach
Outreach efforts for this expedition have continued through
a variety of programs.
Blogs: Current bloggers
this week include our onboard education officer Jennifer Magnusson (personal
and kids blogs) and staff scientist Adam Klaus (operations). We also had guest
posts from Wolfgang Bach (hydrogeology) and Alyssa Stephens (publications/graphics).
Katrina Edwards continues her blog on the Scientific
American Expeditions page and the C-DEBI site. Beth Orcutt
continues to blog about microbiology on the Adopt-a-Microbe website and Amanda
Haddad continues to provide science content and connect with a special needs
audience on the Classroom Connections website.
Videoconferences: Seven live ship-to-shore interactive programs were conducted
with the following audiences: naval engineering students from Spain, 5th
graders from South Carolina, 6th graders from California, university
students from France, 11th/12th graders from Missouri,
and university students from the Virgin Islands. Participation from scientists
has been excellent, and they have indicated that they are enjoying the
interactions with students. Eight conferences are scheduled for next week.
Social
Media: The education officer continues to
post daily updates on the JR Facebook page and Twitter account. Updates include
links to the blog or other pages on the JR website, photos, videos, operational
updates, and classroom activities. A daily math problem contest was posted and
will continue throughout the expedition.
Adopt-A-Microbe: Week 4 activities (classes wrote microbe haiku) were
submitted and Week 5 activities (exploring microbial habitats) were assigned.
Classroom
Connection:Students were on fall break this week,
so there were no activities planned.
Documentary: The videographers have continued full-time filming and
interviewing for their documentary.
Technical Support and HSE Activities
Science Mission Support: Technical staff provided analytical
support for materials recovered from Hole U1382A and assisted with CORK deployment operations.
Other Technical Activities:
- Continue to assist scientists with DESCLogik
- Resolved noise issue on PWL velocity signal but issues with consistent velocity calibrations are still unresolved
- Numerous issues were encountered with various database applications during the processing of Site 1382 cores. Several upgrades appear to have resolved some of the issues
- Work continued on 3D camera project
- Upgraded Winfrog workstation #1 to Windows 7
- Completed installation of a sound control cabinet around the cryo-refrigeration system
The weekly fire and abandon ship drill was held as scheduled.
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