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IODP Expedition 330:
Louisville Seamount Trail
Week 4 Report (3-9 January 2011)
PDF file is available for download.
U1373A, which was spudded on 1 January, was routinely advanced to a depth of
64.0 mbsf when the bit had accumulated 69.7 rotating hours and required replacement.
Basaltic basement was encountered at a depth of 33.9 mbsf. At this juncture, the
penetration into basement was 30.1 m with an average penetration rate of 0.9
m/hr. The strategy of pulling half-cores helped to increase the average
basement recovery to 91%. The average recovery for the entire hole at this
point was 72%. To keep the hole clean of cuttings, the hole was flushed with
20-barrel mud sweeps prior to recovering each core. An additional 40-barrel mud
sweep was circulated before initiating the bit trip.
free fall funnel (FFF) was made up and deployed at 1845 hr on 4 January. The vibration-isolated
television (VIT) was launched and the free fall funnel monitored as the bit was
withdrawn from the hole. The bit cleared the lip of the funnel at 2005 hr and
was on deck by 1210 hr on 5 January. The used bit was found to be in excellent
condition exhibiting slight cone wear, no missing inserts, tight bearings, and
less than 1/8" under-gage in spite of having accumulated 70 rotating hours. A
new bit was made up to the bottom hole assembly (BHA) and deployed along with
an additional stand of drill collars.
0630 hr to 0845 hr the driller attempted a reentry into the FFF, but the bit
appeared to bind about a foot into the throat of the funnel and could not be
advanced further. The mud pump
flow was increased on the chance that any obstruction would be hydraulically
dislodged, but the end result was that the FFF tipped over on its side. It was surmised that the 2.7 m FFF
casing was not lodged firmly in the hole when the old bit was withdrawn. The
only element holding the FFF vertical was the pile of cuttings.
the open hole was not visible on the camera, the driller attempted a blind stab
into the hole by lowering the bit into the sediment cover around the periphery
of the FFF. This course of action was terminated after 2.25 hours and the
decision was made to offset to a recently approved alternate site on the other
side of the seamount summit. After the drill string was picked up to 1111 mbrf,
the vessel was offset in dynamic positioning (DP) mode to new Site LOUI-6B
located 5.6 nmi at a bearing of 253 degrees from Hole U1343A. The 5.6 nmi
offset was accomplished in 3.25 hours and by 1630 hr the vessel was positioning
on the new location. The VIT was deployed and used to monitor the bit tagging
the seafloor at a depth of 1570.0 mbrf or 2.6 m shallower than the corrected
U1374A was spudded with the rotary core barrel (RCB) drill bit at 2035 hr on 5
January. After penetrating a thin (~7 m thick) sedimentary cover, the bit
penetrated igneous rocks at 16.7 mbsf. Rotary coring slowing advanced to a
depth of 120.8 mbsf with an excellent average recovery of 82% by midnight on 10
January. It is planned to suspend coring the next morning to make up and deploy
the third FFF of the expedition to change the bit.
week was a busy week for all laboratory groups. The site report chapters for
Site U1372 had to be finalized and submitted and the Visual Core Description
(VCD) sheets for this site had to be reviewed and corrected. In addition, all
descriptions of cores from Site U1373, which had to be abandoned unexpectedly
early, had to be entered in the database and also the site summary meetings for
this site commenced at the end of this week. Due to the short transit, the
first core at Site U1374 arrived in the second half of this week and the
exceptional high recovery resulted in a large amount of core material that had
to be described.
the abandoned Site U1373 and the new Site U1374 both retrieved considerable
amounts of diverse sediments, the sedimentology laboratory group was particularly
busy. The uppermost sediment at Site U1373 was interpreted to have been a
shallow-marine to beach depositional environment at a previously volcanic
island. This environment was punctuated by "catastrophic" emplacement of a
debris flow deposit, a volcanic interval and lahar(s). Recurrence of such
deposits suggests that deposition took place close to the bottom of a valley,
most probably close to a river mouth. In contrast to Site U1372, no evidence
for subsidence or significant eustatic changes was found in the sedimentary
record of Site U1373. At Site U1374, seven different lithologies have been
recognized so far based on core observations. A stratigraphic subdivision is
currently being established.
pelagic sediments were not recovered at Site U1373, with the exception of a miniscule
amount of recent pelagics mixed with some ground manganese crust in the core
catcher of the first core (U1373A-1R-1). An assemblage of calcareous
nannofossils was identified in these few grams of sediment and preliminarily
assigned to stratigraphic zones CN14a to 15, mid-Pleistocene to Holocene.
Because of the lack of other uncemented sediment, standard paleontological
sample procedures could not be applied at this site. Instead of those standard
procedures, thin section investigations of potentially microfossil-bearing
cemented sediment and biocrusts were conducted. In sedimentary Units I and III,
bivalves, bryozoans, calcareous algae, and echinoderms were found. In addition
to those organisms, the marine oyster Flemingostrea sp. was identified in samples
from Unit IIIB. Unfortunately, the stratigraphic distribution of this genus
spans over a wide range from Upper Cretaceous to Miocene, which makes it not
very suitable for biostratigraphic age determination. In contrast to Site
U1373, soft pelagic sediment was recovered at the Site U1374 and yielded
calcareous nannofossils and abundant planktonic foraminifers. The preliminary
age of this sequence (Unit I) is mid-Pleistocene to Holocene.
total, 38.36 m of igneous rock were recovered from Hole U1373A. This includes
6.10 m of lava flows in the sedimentary cover and 32.26 m in the igneous
basement. The former consists of brecciated lava flows that exhibit jigsaw-fit
texture, which are a feature of blocky peperites. The top of the igneous
basement consists of subaerial flows of highly olivine-titanaugite-phyric
basalt, with the flows becoming aphyric at 2.75 m downhole, and then peperitic
after 3.62 m. Drilling stopped in a >22 m thick inflated sheet flow of
aphyric basalt, which had a 22 cm thick peperitic top. The peperites indicate
mingling between lava and wet sediment, and the overall sequence in Hole U1373A
is interpreted to reflect lava flowing into an area where water and
water-saturated sediments were present, but where the water supply was limited.
date, the description of cores recovered from Hole U1374A has reached 72.80
mbsf, with the first (shallowest) in situ lava flow starting at 16.72 mbsf. The sediment immediately
overlying the upper flows contains several different types of basaltic clasts.
The uppermost lava flow is a 1.32 m thick, highly olivine-phyric basalt.
Beneath this, two aphyric basalt lava flows, 9.29 and 3.25 m thick, are
separated by 4.29 m of volcanic breccia. Below 37.45 mbsf the succession becomes
dominated by thick sequences of volcanic breccia, among which there are two
units of lithic-vitric volcanic sand. The lower 9.13 m of breccia is polylithic
and appears to be sedimentary in origin. At the end of this week, drilling in
Hole U1374A continues to recover this breccia with occasionally interbedded
thin lava flows.
the other laboratory groups, the alteration specialists had to deal with
wrapping up describing the last cores from Site U1373 while at the same time
starting to describe new cores from Site U1374. Macroscopic core descriptions
and thin section observations allowed us to define two main units with
different types of alteration in Hole U1373A based on color difference. These
colors, reddish gray to reddish brown and gray with minor green clay, could be directly
related to the oxidation state of alteration processes: oxidizing conditions
for the reddish units (seafloor to 35 mbsf) and a small hint for reducing
conditions for the more light greenish gray units (35 to 66 mbsf). With a few exceptions in
relatively fresh clasts, olivine is generally completely altered to iddingsite
in the upper portions of the hole. Below ~30 mbsf, the olivine is systematically
replaced by green clay and minor Fe-oxyhydroxides. Additionally, three main
groups of alteration phases could be distinguished in veins and vesicles:
carbonates, clay minerals (saponite, nontronite, montmorillonite, celadonite,
bannisterite), and other secondary phases (such as zeolites, clinochlore, Fe
oxyhydroxides, and some pyrite/chalcopyrite). Besides doing visual observations, the alteration specialist group
is also getting progressively familiar with XRD data processing using the
specific instrument software (EVA), which results in improved interpretation of
the conducted XRD analysis.
structural geology laboratory group completed the identification and
description of veins, joints, geopetals, and flow textures found within core and
thin section samples from Hole U1373A and started describing structural
features for Hole U1374A cores as well. In Hole U1373A fractures and veins are
common to abundant in lava flows, but are rare to absent in breccias. Magmatic
foliations in the lowermost unit of Hole U1373A show a range in orientations,
from sub-horizontal to near-vertical, indicating that this thick flow (>22
meters) underwent several episodes of lava injection and flow inflation. Dip
angles for veins and fractures in Hole U1373A display a bimodal distribution,
with the shallow features being sub-parallel to flow boundaries, and steep
features representing conjugate structures. Rocks recovered from both Holes
U1373A and U1374A contain several horizontal geopetals, which indicate that the
entire pile of rocks has not been tilted since formation.
total of 10 samples of igneous rocks from Site U1373 were analyzed for major
and trace element concentrations by ICP-AES. The samples are from stratigraphic
Units I, II, IV, VI, and VII and interpretation of the data is underway. In
addition, 6 samples were collected from the
unconsolidated sediment of Core U1374A-1R (from the new site) for determination
of carbonate, organic carbon and organic nitrogen content. Analysis of these samples is planned for the next week.
Physical Properties group continued running tests this week on whole core and
discrete samples from Holes U1372A, U1373A, and U1374A. Whole round and split
half core measurements have been completed for all Hole U1373A samples (Cores
-1R to -13R) and for Cores U1374A-1R to -12R along with natural gamma ray
testing with a total count time of 1.5 hours. Nondestructive thermal
conductivity tests were performed on 12 selected intervals from Cores U1373A-1R
to -13R and 5 selected intervals from Cores U1374A-1R to -7R. Discrete samples from Cores U1373A-1R
to -13R and U1374A-1R to -7R were chosen in collaboration with the paleomagnetism
group, and the entire set of paleomagnetic, P-wave, and moisture and density
measurements have been completed for all samples from Hole U1373A. The
automated data-filtering program for processing whole round and section half
multi-senor logging (HRMS and SHML) data was revised to make it more
user-friendly, as well as to add new features and fix computer bugs. The
filtered data have been proven useful for identifying interesting changes in
magnetic susceptibility and natural gamma ray counts along the core and changes
in color reflectance that correspond with different alteration characteristics.
paleomagnetism laboratory group has alternating-field (AF) demagnetized all archive half-cores from Site U1373 with the
cryogenic magnetometer system up to a peak field of 70 mT, and the remanent
magnetization was measured at 2 cm intervals. AF demagnetization was carried
out on a total of 23 discrete 8 cm3 cubes up to a peak field of 200
mT, and thermal demagnetization was carried out on 11 discrete samples up to a temperature
of 675°C. These data have been processed and analyzed to
produce a plot of the variation in inclination downhole. Fisher- and
inclination-only statistics have been used to average inclinations within core
pieces and also within lithological units. Also this week, remanent
magnetization measurements with AF demagnetization have been conducted for the
upper 10 archive half-cores from the Site U1374. Fifteen discrete samples have
already been AF demagnetized, and 10 discrete samples are undergoing thermal
Sixteen samples of various lithologies were collected for microbiology analysis
this week, including unconsolidated sediment, sandstone, volcanic breccia and
basalt. Contamination tests via microsphere deployment and analysis were
conducted on two samples, one from Hole U1373A and the other from Hole U1374A.
Analysis of these tests indicated little to no contamination in the drill cores.
Drill fluid was collected to provide additional data for the contamination
testing. In addition to the standard suite of samples collected and preserved
for cell counts, molecular biology and stable isotope analysis, five samples
were used to inoculate various culturing media, and three samples were used to
initiate stable isotope bioassays to measure metabolic rates of subsurface
microbes. A special sample processing technique, dubbed "enhanced
extraction" and including the use of a blowtorch and hydraulic press, was
developed to retrieve larger interior portions from the whole round samples for
use in these bioassays. The microbiology group is particularly pleased with
this enhanced extraction technique.
Education and Outreach
in the previous weeks, the educator ("Teacher at Sea") continued posting daily
blogs on the JOIDES Resolution (JR) website and Facebook page. The JR website had 1,418 visits between January 2 and
January 8. Of those, 641 were new visitors. The JR Facebook posts increased from
11,500 to over 20,000 views a day during the week, and increased its followers
from 2,245 fans on January 1 to 2,254 fans on January 8. The twitter account "@TheJR" gained 6 new followers.
videoconferences with separate fifth grade, eighth grade and ninth grade
classes at three different U.S. schools were conducted this week. The
scientists Patrick Fulton, Alex Nichols and Christoph Beier participated in
question-and-answer periods with the students.
The videographer worked with co-chief scientist Anthony Koppers to refine the "Mission
of Expedition 330" video, recorded semifinal narration, and is working on an
important but complex animation demonstrating mantle plumes, plate motion, and
seamount chains. She arranged and shot video of the "coring" of a spectacular
seafloor cake with 7 layers, specifically baked for the purpose by the ship's
catering crew. She also got permission to mount a miniature camera to a helmet
worn by a drill floor worker who then went into the rigging. This produced
about an hour of amazing video footage with a bird's eye view from the derrick.
In preparation for videoconferences and other interviews that happened during
this week, she fitted neutral density film to the window in the paleontology
laboratory, and tested it out with a brief interview with shipboard scientist
Jeff Gee. She continues to shoot various moments as they occur, like the
dropping of the free fall funnel, and posts daily on the JR Facebook and
twitter pages. In addition, she organized and prioritized her video plans with
the help of Ocean Leadership's educational department (Deep Earth Academy).
Technical Support and HSE Activities
Technical staff engaged in providing full support for coring operations at Sites U1373 and U1374. Other activities include the following:
1. Completed relocation of whole core track amplifiers;
2. Continued work on minor software upgrades to various applications;
3. Continued effort on software development for the core liner engraver continues, and prepping installation site in core entry.
The weekly fire and boat drill was held as scheduled. No HSE incidents to report.