Scientific Reports
Scientific Reports
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Date: Tue, 9 May 2000 16:05:01 +0000 (GMT)
From: Jim Charters <melville!charters@sdsioa.UCSD.EDU>
Reply-To: Jim Charters <melville!charters@sdsioa.UCSD.EDU>
Subject: Final Science Report from R/V Melville - NEMO Expedition Leg2 May9, 2000
To: shipsked@ucsd.edu
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Date: Tue, 9 May 2000 09:57:40 -0600
To: charters, abowen@whoi.edu, bwalden@whoi.edu, rpittenger@whoi.edu,
depp@nsf.gov, ashor@nsf.gov, master, relder, mperfit, mtolstoy, rcomer
From: dfornari (Daniel J. Fornari)
Subject: Final Science Report from R/V Melville - NEMO Expedition Leg2 May9,
2000
Final Science Report from R/V Melville
NEMO Leg 2
To: Dr. R. Knox
SIO Marine Facilities
From: Dan Fornari on board R/V Melville
Date: May 9, 2000
Subject: Final Science Report from R/V Melville - NEMO Expedition Leg2
The last 9 days of station time on this leg was spent completing the
DSL-120 surveying of the Galapagos Rift valley in the area around 97.5°W,
followed by an Argo II lowering to investigate the volcanic and structural
terrain of the rift valley floor. We mapped the entire rift valley floor
with DSL-120 and surveyed various locations both along the rift axis where
most of the largest volcanic centers are, as well as other locations
throughout the rift valley and along part of the northern bounding wall.
We also completed several detailed surveys with Argo II at several
locations both along the axis of the rift and within the rift valley over
specific epicenter sites in the Tphase data. Four small volcanoes dominate
the rift valley floor along this segment of the Galapagos Rift. One
striking finding is that there appears to be extensive volcanic
construction, some of it young (based on cross-cutting relationships)
throughout the rift valley floor which is ~4.5 km wide. We saw extensive
cracking and faulting and extensive lowT hydrothermal staining/clay mineral
development on the glassy basalts on the western volcano summit. The final
few days of station time were dedicated towards dredge (13 total) and rock
core (18 total) sampling, at a good first-order level of the principle
volcanic features within the rift valley floor. MAPR data both from the
DSL-120 and Argo II lowerings did not show any evidence for hydrothermal
vent sites, and we saw no vent-related animal communities in the areas
surveyed using Argo II.
Summary statistics for the NEMO Leg2 are as follows:
Distance traveled by R/V Melville on this expedition = 9,445 km
Duration of DSL-120 sonar data collection = 8.9 days
Number of kilometers surveyed by DSL-120 sonar = 562 km
Total seafloor area surveyed by DSL-120 sonar = ~474 km2
Duration of Argo II data collection = 7.4 days
Number of kilometers surveyed by Argo II = 238 km
Number of Dredges = 45
Number of Rock Cores = 45
Number of CTD casts = 1
Number of gigabytes of raw sonar data = 150 gigabytes
Number of gigabytes of processed sonar data = 5 gigabytes
Number of Hi-9 video tapes recorded = 188
Number of digital video tapes recorded = 94
Number of digital still images recorded by Argo II = 50,362
Number of 35mm photographs recorded by Argo II = 2,161
Number of frame grabs recorded by Argo II = 5,350
Size of shipboard data web site = 5.5 gigabytes (>350,000 files)
Several new hydrothermal vent areas discovered on the
East Pacific Rise between 1° 40'N and 1° 45'N
All the science party take this opportunity to sincerely thank the officers
and crew of R/V Melville, the Scripps Technicians on board, the WHOI Deep
Submergence Operations Group, and the shorebased support staffs at SIO and
WHOI who all provided exceptional support and expertise throughout this
leg. Without the dedication, good spirit and highly-skilled capabilities
of these people the collection of the extensive data set acquired on this
leg would not have been possible. They are a tribute to their respective
institutions and the UNOLS fleet.
Best Regards,
Dan Fornari, Mike Perfit, Maya Tolstoy
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Date: Fri, 28 Apr 2000 00:14:39 +0000 (GMT)
From: Jim Charters <melville!charters@melville.ucsd.edu>
Reply-To: Jim Charters <melville!charters@melville.ucsd.edu>
Subject: Weekly Science Report from R/V Melville - NEMO Expedition Leg2 April 19 to April 27, 2000
To: shipsked@sdsioa.ucsd.edu
Weekly Science Report from R/V Melville
NEMO Leg 2
To: Dr. R. Knox
SIO Marine Facilities
From: Dan Fornari on board R/V Melville
Date: April 27, 2000
Subject: Weekly Science Report from R/V Melville - NEMO Expedition Leg2
April 19 to April 27, 2000
In order to justify the drop off of two members of the science party, and
permit a short breakin the long cruise leg, R/V Melville arrived in Puerto
Ayora, Santa Cruz Island on April 19. Starting
on April 21st, we conducted a short multibeam mapping and dredging program
around the western Galapagos Islands. On April 24th Melville commenced the
transit north towards the Galapagos
Rift near 97.5°W, the last planned survey area of this leg, to investigate
intense Tphase
seismicity which occurred 18 months ago. We arrived on site on April 26th
and completed
a ~7hr multibeam survey which includes the entire rift valley and flanking
rift mountains
between 97° 20'W to 97° 50'W, and between ~2° 00'N and 2° 15'N. The rift
valley floor
is ~4.5 km wide and contains discrete closed contour highs aligned nearly
parallel to the
trend of the valley and approximately in the middle of it, suggestive of
volcanic constructional features along a neovolcanic zone in the rift
floor.
We are currently surveying the rift valley using the DSL-120 sonar system
(Lowering #069) and have completed about half of the nearly 80 nm of line
required to
map the entire rift valley floor. We expect to complete the DSL-120 survey
by tomorrow
evening (April 28) and commence transponder deployment and dredging
operations. That
will be followed by Argo II lowering(s) and additional sampling work.
Best Regards,
Dan Fornari, Mike Perfit, Maya Tolstoy (Co-Chief Scientists)
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Date: Thu, 6 Apr 2000 04:37:31 +0000 (GMT)
From: Jim Charters <gmelville!charters@sdsioa.ucsd.edu>
Reply-To: Jim Charters <gmelville!charters@sdsioa.ucsd.edu>
Subject: Weekly Science Report from R/V Melville - NEMO Expedition Leg2 March 30 to April 5, 2000
To: shipsked@sdsioa.ucsd.edu
Weekly Science Report from R/V Melville
NEMO Leg 2 - March 30 to April 5, 2000
To: Dr. R. Knox
SIO Marine Facilities
From: Dan Fornari on board R/V Melville
Date: April 5, 2000
We have completed the DSL-120 sonar surveying of the axial zone between
10degN and 9deg 08'N. Sonar data quality is excellent. Correlation between
phase-bathymetry and sonar backscatter is superb using AVG developed on board.
All data are in the last stages of final processing for backscatter and
phase-bathy and being input into various data analysis packages and prepared
for web-posting for use by the general community shortly after we return
from the cruise.
On March 30, at ~1600z, Melville transited from the 9-10N EPR work area
down to the 3deg 20'N survey site. We arrived on March 31 ~1800Z and
commenced a multibeam survey
of the 3deg 20'N overlapping spreading center which took approx. 8 hrs.
Deployment
and surveying of 3 transponders followed the multibeam survey.
We deployed the DSL-120 sonar on April 1 at ~2150Z to commence a sonar
survey of the
overlap basin and EPR axis over the area where t-phase seismicity was recorded
~4 years ago by the NOAA autonomous hydrophone array. We covered the EPR axis
for approx 15 nm from the min. depth near 3deg 9'N to the tip of the
southern ridge
axis on 4 survey lines with the DSL-120, and have completed a survey of
most of the
overlap basin in the region covered by the t-phase epicenters.
Three dredges were carried out on the EPR flank, east of the axis near 3deg
26.5'N
Argo II was deployed on April 4 at ~1820Z and is still surveying seafloor
targets
selected based on the DSL-120 sonar imagery and bathymetry. We expect the
lowering
to last until tomorrow, April 6, at which point we will commence sampling
operations.
Best Regards,
Dan Fornari, Mike Perfit, Maya Tolstoy (Co-Chief Scientists)
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Date: Fri, 31 Mar 2000 02:58:55 +0000 (GMT)
From: Jim Charters <gcharters@sdsioa.ucsd.edu>
Reply-To: Jim Charters <gcharters@sdsioa.ucsd.edu>
Subject: Weekly Science Report from R/V Melville - NEMO Expedition Leg2
To: shipsked@sdsioa.ucsd.edu
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Date: Thu, 30 Mar 2000 19:53:02 -0700
To: charters, abowen@whoi.edu, bwalden@whoi.edu, rpittenger@whoi.edu, depp@nsf.gov,
ashor@nsf.gov, master, relder, mperfit, mtolstoy
From: dfornari (Daniel J. Fornari)
Subject: Weekly Science Report from R/V Melville - NEMO Expedition Leg2
Weekly Science Report from R/V Melville
NEMO Leg 2
To: Dr. R. Knox
SIO Marine Facilities
From: Dan Fornari on board R/V Melville
Date: March 30, 2000
Melville departed Manzanillo Mexico on March 24th at about 2100Z and headed
south
for the East Pacific Rise near 9deg 50'N to conduct DSL-120 sonar surveys
of the ridge crest area between 9-10degN. Transit speed heading south was
excellent,
at times reaching 14 knots. On March 26 at 1330Z we carried out the
SeaBeam roll-bias
test at a site on the EPR axis just south of the Clipperton transform near
10deg 04'N.
J. Charters, the computer tech. analyzed the test data and determined that
the current
settings for the system are good.
We first lowered the DSL-120 sonar at 2142Z on March 26 (Lowering 065). After
reaching the bottom the sonar was not pinging and had to be recovered. On
recovery, a
bad IC chip was found to be the problem. Subsequently, the system was
repaired and was redeployed on Lowering 066 on March 27 at 1430Z.
Sonar surveys along the axis of the EPR continued for nearly three days to
March 30 at 1330Z.
Nearly 160 km of survey line were run with excellent records collected.
Data acquisition
included an initial crossing line at 9deg 37'N within a transponder
network. Cross
correlation between N-S and E-W lines is superb.
After recovering the DSL-120 sonar, we transited north collecting multibeam data
along the axis from 9deg 10'N to 9eg 35'N where we recovered 3 transponders.
All recovery operations were completed by 2200Z and we got underway to our next
survey site near 3deg 20'N on the EPR crest. We are heading to the eastern
Siqueiros-EPR intersection and will then continue to survey down along the
EPR axis with multibeam to 3deg 20'N.
All else going very well. Excellent support from the officers, crew and
technicians
on board Melville.
Best Regards,
Dan Fornari, Mike Perfit, Maya Tolstoy (Co-Chief Scientists)
This cruise is being funded by a grant from the National Science Foundation
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