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IODP Expedition 330:
Louisville Seamount Trail
Week 9 Report (7-11 February 2011)
PDF file is available for download.
Hole U1377A on Hadar Guyot (Prospectus Site LOUI-4B) needed to be abandoned the
vessel was slightly offset and Hole U1377B was spudded on 6 February. Rotary
coring advanced the hole to a final depth of 37.0 mbsf with an average recovery
of 39% when time on site expired. After the drill string was recovered, and the
beacon retrieved, the vessel departed Site U1377 for Auckland at 0730 hr on 8
February. The time on Hole U1377B was 57.5 hours and the total time on site was
70.0 hours (2.9 days). Because of concerns of heavy wind and rough seas on the
transit to Auckland, the vessel departed the location approximately 18 hours
earlier than originally planned. Despite experiencing strong headwinds during
the first half of the voyage (resulting in a drop of transit speed to ~9 knots)
the vessel arrived in Auckland on 11 February about 12 hours earlier then
originally planned. With the first line ashore at 17:09 Expedition 330 has
ended. In total 1114 m of sediment and igneous basement were cored at 8 holes
at 6 sites located on 5 different seamounts and 806 m of core was recovered
corresponding to 72% recovery.
the last week of Expedition 330 we finished coring operations on Hadar Guyot
and started our transit to Auckland. All laboratory groups described and
analyzed the last cores and samples from Site U1377, prepared site reports and
cleared their workspaces.
limited by a very poor recovery, the material obtained in Holes U1377A and
U1377B defines a consistent sedimentary pattern on top of Hadar Guyot. Two
units were recognized based on macroscopic and microscopic observations of the
sediment. Unit I was recovered at Holes U1377A andU1377B and represents the
uppermost sediment of Hadar Guyot. The sediment is composed of a nannofossil
foraminiferal ooze, which strongly resembles the soft sediment recovered in the
uppermost part of Sites U1372 on Canopus Guyot, U1374 on Rigil Guyot, and U1375
on Achernar Guyot, and is considered to reflect recent pelagic sedimentation on
top of the drilled seamount. The ooze contains a mixed assemblage of calcareous nannofossils and planktonic foraminifers indicating an early Pliocene to Holocene age. Unit II corresponds to few cuttings recovered in
Section U1377A-3R-CC, and ten small-sized (<20 cm-thick) pieces recovered
from Holes U1377A and U1377B. Unit II includes (1) a middle-late Eocene
foraminiferal limestone with abundant planktonic foraminifers, a few
ferromanganese encrustations, and rare shallow marine bioclasts (e.g.,
echinoderm fragments); and (2) a latest Paleocene-early Eocene, heterolithic
multicolor basalt conglomerate with a few ferromanganese encrustations. The
matrix of the conglomerate is composed of foraminiferal limestone with abundant
plantkonic foraminifers and a few shallow marine fossils (e.g., echinoderm
fragments, larger foraminifera, shell fragments, and gastropods). Preliminary age
assignments of the foraminifer content of the limestone (based on thin section
observations) range from middle to late Eocene for Hole U1377A and late Paleocene-early Eocene for Hole U1377B. The faunal
assemblages and sedimentary textures indicate that Unit II at Site U1377
represents a (or several) condensed section(s) likely to have deposited in a
shallow marine to hemipelagic-pelagic environment on top of Hadar Guyot.
Below the sedimentary Units I and II, igneous
basement was encountered at 9.1 mbsf in Hole U1377B and a total of 27.9 m of
igneous rocks were cored. The upper part of the succession consists of a
single, 10.1 m thick unit of flow-banded trachybasalt similar to that in Hole
U1377A, whereas the lower part consists of 17 small (up to 2.1 m thick)
trachybasalt units with curved and glassy margins. These suggest that this
lower part of the succession is composed of pillow lava or small lobate flows
erupted in a submarine environment. The upper 3.8 m interval of this lower
group contains small amounts of olivine, plagioclase and augite phenocrysts,
sometimes in glomerophyric clusters, while the lower part is aphyric. A curious
feature of this interval is that, in several instances, the inter-pillow space
is filled with glass that connects with the more massive interior of the unit
below. It appears that lava in the still molten interior of a pillow has broken
out as a protrusion that filled the space between overlying pillows.
Alternatively, magma may have been injected into a stack of pillows, but the
similarity in appearance between injected and pillow trachybasalt suggests
that, in either case, both were part of the same eruptive event. The strong
flow banding seen in both holes suggests that the rocks recovered at Site U1377
are generally alkalic and have probably the most evolved composition of all the
rocks drilled during Expedition 330.
structural geologists found a single geopetal structure in rocks from Hole
U1377B indicating that this part of Hadar seamount experienced no tilting after
deposition. Veins, vein networks, and vesicle bands are present in both holes,
while chilled contacts were only observed in Hole U1377B. Vesicle bands in Hole
U1377A have either moderate or sub-horizontal dips. Vesicle bands and chilled
contacts in Hole U1377B are moderate to steep, with dips ranging from 45 to 90¼.
In Hole U1377B glass occurs on chilled pillow margins, along the edge of a
small intrusion, and in the matrix of a breccia. These last two glass
occurrences indicate forceful intrusion and rapid cooling of new magma into
already solidified rocks.
to time constraints at the end of this expedition only a single sample could be
analyzed geochemically from Site U1377. Its basaltic trachyandesitic
composition confirms the evolved nature of the volcanic rocks drilled at this
site. No samples were collected or analyzed for determination of carbonate,
organic carbon, or organic nitrogen content during this week.
archive half-cores from Holes U1377A and U1377B were measured and
alternate-field (AF) demagnetized using the cryogenic magnetometer, and
principal component directions have been automatically picked. In addition, 10
discrete samples from Hole U1377A have been AF or thermally demagnetized, but
only natural remanent magnetizations were obtained for seven samples from Hole
U1377B due to a malfunction of the AF demagnetizer. Both the archive half-core
and discrete sample remanent magnetizations in Hole U1377A provided generally
consistent, moderate to steep positive inclinations, reflecting southern
hemisphere reversed polarity. The archive half cores from Hole U1377B also
yielded reversed polarity remanent magnetizations.
and split-half physical properties measurements were completed for all sections
from Hole U1377B, as was natural gamma ray radiation testing. The last group of
discrete samples was chosen from Hole U1376B (through Core U1376B-5R-3) in
collaboration with the paleomagnetists. The entire set of paleomagnetic,
compressional wave velocity, and moisture and density measurements have been
completed for all samples from Hole U1377B. The remainder of the expedition
focused on preparing the data filtering program for future expedition use.
Downhole Logging team gave their Site U1376 presentation this week and worked
on finalizing site reports for Sites U1374 and U1376. Additionally,
post-logging tests have been performed on the GBM with the main wireline.
One final sample was taken by the Microbiology group from Core U1377B-4R and
processed for cell counts, molecular biology and in situ stable isotopes. In
addition, 18 incubations were started with nine media targeting growth of
sulfur oxidizers, iron cycling microbes and general heterotrophs. A stable
isotope addition bioassay was also initiated for studying growth rates of
subsurface microbes of Hadar Guyot. Sampling of previously initiated stable
isotope addition bioassays from Sites U1373 to U1376 continued as the ship
transited back to Auckland and the microbiology laboratory was cleaned and
samples prepared for shipment.
Education and Outreach
the education officer and the videographer continued blogging and conducting
video broadcasts during the last week of this expedition. Over the course of
the expedition, the education officer has posted photos, links and status
reports daily, as well as a weekly trivia contest, to the JR Facebook page.
During this time, the Facebook page has had 746,979 post views and gained 139
fans. He has also maintained the Expedition 330 outreach content on the
joidesresolution.org website, including posting 37 blog using three different
blog accounts: JR junior (for kids age 8-12), Educator Ideas (for classroom
teachers and informal educators) and Kevin Kurtz (for high school students and
adults). The JR website has had over 10,339 visits during the course of the
expedition with 4,943 new visitors. He also coordinated and facilitated, with
the help of the videographer and the expedition scientists, 27 successful
webcasts with schools and museums. Fifteen of the scientists in the science
party participated in question and answer periods. Just over 1000 children and
adults participated in the live webcasts, and one school recorded the webcast
to show to the rest of their students, adding 750 viewers to the total. The
videographer finished recording and editing her last videos "Leavin' Louisville"
and an official Exp 330 wrap up video.
Technical Support and HSE Activities
staff engaged in providing full support for coring operations at Site U1377 and
end of expedition activities. Other support technical activities included the
1. Continued minor software upgrades to various applications.
2. Deployed the towed magnetometer for the transit into Auckland.
3. Prepared laboratories for the upcoming STP visit to the ship.
No HSE incidents to report.