Sojourn Expedition
Sojourn Expedition
R/V MELVILLE
Leg 1
Dan Scheirer (401) 863-1701
Brown University email: scheirer@emma.geo.brown.edu
Department of Geological Sciences
Box 1846
Providence, RI 02912
Marie-Helene Cormier (Milene) (914) 365-8351
Lamont-Doherty Earth Observatory email: cormier@ldeo.columbia.edu
Geoscience Building, #103
Palisades, NY 10964-8000
San Diego - Papeete
08 September - 21 October 1996
Leg 2
Rachel Haymon (805) 893-3718
University of California, Santa Barbara email: haymon@magic.geol.ucsb.edu
Marine Science Institute
Santa Barbara, CA 93106
Papeete - Valparaiso
27 October - 11 December 1996
Leg 3
transit from Valparaiso to Cape Town
15 December 1996 - 5 January 1997
Leg 4
Thomas Whitworth III (409) 845-5872
Texas A&M University email: twhitworth@tamu.edu
Department of Oceanography
College Station, TX 77843-3146
Cape Town - Fremantle
08 January - 16 February 1997
Leg 5
David Christie (541) 737-2296
Oregon State University email: dchristie@oce.orst.edu
School of Oceanography
Corvallis, OR 97331
Fremantle - Hobart
19 February - 03 March 1997
Leg 6
Douglas S. Luther (808) 956-58755
University of Hawaii at Manoa email: luther@foliatus.soest.hawaii.edu
Department of Oceanography
1000 Pope Road
Honolulu, HI 96816
Hobart - Hobart
06 March - 07 April 1997
Leg 7
transit from Melbourne to Papeete
11 May - 24 May 1997
Leg 8
Alan Chave (508) 457-2000 x 2833
Woods Hole Oceanographic Institution email: alan@faraday.whoi.edu
Woods Hole, Ma 02543
Papeete- San Diego
27 May- 28 June 1997
SCRIPPS INSTITUTION OF OCEANOGRAPHY
CONTACTS
Robert A. Knox (619) 534-4729
Assoc. Director, Shipboard Operations and email: rknox@ucsd.edu
Marine Technical Support
Captain Tom Althouse (619) 534-1643
Marine Superintendent, Nimitz Marine Facility email: capt@mpl.ucsd.edu
Christian de Moustier (619) 534-1784
Scientific Advisor to Shipboard email: cpm@mpl.ucsd.edu
Technical Support Services
SEA BEAM information contact
Woody Sutherland (619) 534-4425
Manager, Shipboard Technical email: woodys@odf.ucsd.edu
Support Services
Stu Smith (619) 534-1898
Head, Geological Data Center email: ssmith@ucsd.edu
Ron Moe (619) 534-6054
Head, Shipboard Computer Group email: rmoe@ucsd.edu
Bob Wilson (619) 534-1632
Head, Resident Marine Technician Group email: restech@sdsioa.ucsd.edu
Rose Dufour (619) 534-2841
Elizabeth Rios email: shipsked@ucsd.edu
Ship Schedulers
Preface
Sojourn Expedition begins with R/V MELVILLE leaving San Diego on 8 September 1996,
headed straight for work south of the equator. This is where she remains for the
entire expedition, except to transit home in June 1997. Sojourn is also a French
word meaning to temporarily visit and move on; and this exactly what MELVILLE does
on her "southern journey." We plan to visit three oceans; Pacific, Atlantic, and
Indian Oceans on this around-the-world expedition, covering over 33,000 nautical miles.
While on this tour, MELVILLE will conduct SEA BEAM surveys, collect magnetics, do
AMS-120/ARGO operations, accomplish two mooring recoveries along 20oS and south of
Hobart, and finally recovery EM arrays and other instruments at the MELT site at 17oS.
This brings MELVILLE full circle in less than 10 months. We are currently planning
to fulfill our bi-annual overhaul and ABS inspection while in Australia.
The entire Sojourn Expedition is being funded by the National Science Foundation.
Leg 1
Dan Scheirer
Brown University
San Diego - Papeete
08 September - 21 October 1996
The primary activity proposed is to map the east flank of the East Pacific Rise (EPR)
between 15-20 S, from near the rise axis out to crust of age 4 Myr. Gravity, magnetic,
SEA BEAM side-scan sonar and bathymetric data will be collected with continuous coverage
for the latter two data sets. The original motivation for focusing on this area was the
observation of long wavelength plate motion-parallel gravity lineations which span the
southern Pacific ocean basin west of the EPR. An earlier NSF-funded project mapped the
ultrafast spreading EPR axis and its west flank out to approximately 4-6 Myr, so this
effort would complete the mapping of this very exciting area. In this region, there are
four major anomalous features: gravity lineations, abundant seamounts, asymmetric
subsidence, and asymmetric spreading. Their coexistence near this part of the EPR must
be more than coincidence. However, with the existing, mainly one-sided data coverage, it
is difficult to distinguish whether these factors are simply a function of the ultrafast
spreading at the southern EPR or whether they are related to some unusual properties of
the Pacific Plate and its asthenosphere. The primary questions to be addressed are:
1) Are there gravity lineations on the Nazca Plate similar to those observed on the
Pacific Plate in this area? 2) Does small-scale convection in the Pacific asthenosphere
bring about the anomalousy low subsidence of young Pacific seafloor?
3) Are the seamounts and seamount chains symmetrically distributed about the axis?
4) Do Nazca Plate seamounts continue to form, remain active, and change in morphology
as those on the Pacific Plate? 5) What is the connection between the seamounts and
the gravity lineations? 6) Can repeated rapid migrations of ridge axis discontinuities
account for most (or all) of the asymmetric spreading? 7) How is the long-wavelength
segmentation of the SEPR expressed off-axis? While we are transiting past the Mexican
EEZ we would like to keep the SEA BEAM 2000 operating as well as collect magnetics and
gravity. During the transits to and from the study area, we may deviate slightly from
a straight course to complement the database on some poorly mapped features, such as
the west flank of the southern EPR down to 15 S, the anti-Bauer scarp (around 110-120 W,
0-10 S), or the linear volcanic ridges stretching between the study area and the Society
Islands.
Leg 2
Rachel Haymon
University of California, Santa Barbara
Papeete - Valparaiso
27 October - 11 December 1996
Our primary propose is to survey the narrow axial zone of the ultrafast-spreading EPR
at 17o18'-42'S using the fiber-optic ARGO II near-bottom optical/acoustic system and
the AMS-120 sonar system. Our goal is to test the hypothesis (based on ARGO data from
EPR 9-10oN) that along-strike thermal gradients set up by the segmented pattern of magma
supply to fast-spreading MOR's exert primary control on the distribution and types of
hydrothermal vents and vent biota, as well as on variations in fine-scale volcanotectonic
characteristics along the axial zone. On the 4th order scale at EPR 9-10N, this magmatic
control of hydrothermal discharge is manifested by the concentration of high-temperature
vents along eruptive fissures. EPR 17o18'-42'S is a superb area for further investigation
of relationships between magmatic processes and other axial processes. Along a segment of
ridge only 45 kms long, seismic data show that the axial magma chamber (AMC) changes along
strike from a flat-topped body at relatively constant depth to a peaked cupola ("spike")
that intrudes to within 0.8 km of the seafloor at 17o27'S. This represents the most
extreme along-strike variations in thermal gradients that we know of on the MOR, and
contrasts with the flat-topped AMC at EPR 9-10N. The survey we propose is designed (and
will be interpreted) within the context of seismic reflection/refraction data, SeaMARC II
and MR1 imaging, SEA BEAM bathymetry, gravity and magnetic data, submersible observations,
and extensive petrologic/geochemical data that exist already for the proposed study area
and adjacent ridge flanks. These data show that this apparently unsegmented portion of
the EPR is actually partitioned into at least six 4th-order segments (our proposed survey
may reveal more), and that the axial zone exhibits along-strike changes in morphology and
some extreme along-strike changes in axial lava compositions. Ridge morphology and some
visual observations indicate recent eruptive activity in part of the proposed survey area.
Beyond testing ideas about coupled magmatic/hydrothermal segmentation along the MOR, we
will also observe how hydrothermal and other axial zone processes are affected by ultrafast
spreading rates and extreme along-strike thermal/magmatic gradients. We will determine
the nature of the axial troughs found along portions of the axial zone in the proposed
study area (axial summit caldera or graben?) and investigate the development of these
important axial features. To this end, we will carry out a secondary ARGO survey of a
hydrothermally-active portion of the axial summit graben on the segment south of the main
survey area (at approx. 18.5S). Finally, we will provide a baseline survey of the
fine-scale segmentation and distribution of vents and biota along a ridge segment destined
for future seismic and submersible studies.
We propose to carry out a 36 day cruise that consists of: 2 days of AMS-120 surveying,
19 days of ARGO-II surveying; 2 days for ARGO II maintenance checks (required every
three days, with a turnaround time of 6 hours); 2 days for deployment/surveying/ recovery
of acoustic transponders used in navigation; and 11 days of transit (from Tahiti to the
survey area, and then to Easter Island). We are not proposing any ship time for additional
dredge sampling of basalts or hydrothermal deposits (beyond that of Sinton et al., 1991)
because the length of the cruise would be prohibitively long.
SeaMARC II records indicate that the axial zone is relatively narrow (<400 m) throughout
the survey area. To achieve sufficient density of coverage, we plan to drive fourteen 45
km-long, axis-parallel lines through the axial zone with line spacings of 10-30 m. This
will provide us with 100% saturation coverage where the axial zone is <100 m wide, ranging
down to a minimum coverage of 45% where the axial zone widens to 400 m. [For the 83-km long
ARGO survey at EPR 9-10oN, we achieved a maximum of 80% coverage where the axis was narrowly
defined by an ASC <200 m wide, and 40% coverage for the southern third of the survey area
where the location of the ridge axis was less well-defined by the structure of the
axial zone.]
Accurate navigation is absolutely necessary to achieve the close line spacings required
for our proposed survey and to determine the relative locations of fine-scale features
with respect to each other. For the proposed survey we will follow the procedures that
we established for our 1989 ARGO I survey to attain a navigational precision of +5 m
throughout the survey area. At the outset of the survey we will lay out a line of 11
bottom-moored acoustic transponders spaced 1 km west (or east) of the ridge axis and ~5
km apart. These will be surveyed in using GPS navigation and accurate depths at the drop
points. Navigation of the ARGO II vehicle can then be acquired by ranging off successive
pairs of transponders as the vehicle travels along strike.
For the proposed program, Haymon will be chief scientist at sea, and Macdonald will be
co-chief scientist. The PI's will share responsibility for data acquisition and analysis.
ARGO II watches require 5 people. DSOG provides 2 people per watch and the science party
must supply 3 per watch. One of the watchstanders is designated as a datalogger. This
person watches the real-time video and logs observations digitally in real time. In this
way we can manage the huge visual dataset. The datalogger files are subsequently edited
by going back to the tapes to review and verify the logged observations. By this means
the classification of features is standardized and erroneous data are deleted from the
files. The end product is a set of digitized and categorized GIS/ArcInfo files that can
be plotted in any combination (for example, black smokers and fissures; vent communities
and Age 1 lavas; etc.). This is a very powerful approach to data management that has
worked beautifully for the EPR 9-10N ARGO I dataset.
Dan Scheirer has been separately funded by NSF to carry out an ancillary study of magnetics
measured with a magnetometer mounted on the ARGO, and to analyze high resolution bathymetry
collected with a Mesotech sonar that will also be incorporated on to the ARGO sled.
We will also collect CTD and transmissometer data using instruments mounted on the ARGO
sled and on the towing cable.
Leg 3
Transit from Valparaiso to Cape Town
15 December 1996 - 05 January 1997
This transit from Valparaiso to Cape Town will take MELVILLE through the straits of
Magellan during the beginning of the austral summer.
During the transit across the Atlantic to Cape Town the ship will conduct a SEA BEAM
survey in the transit mode, and collect magnetics.
No other science is anticipated at this time.
Leg 4
Thomas Whitworth III
Texas A&M University
Cape Town - Fremantle
08 January - 16 February 1997
Description of activities and requirements for WOCE current meter array ICM3 recovery cruise.
The cruise has two basic scientific objectives:
1. To recover an array of 60 current meters on three arrays of 20 moorings and
2. To make CTD/rosette stations spanning each array.
The current meters are deployed along 20S between approximately 93E and the continental
slope of Madagascar in three arrays:
Array ICM3E consists of 7 moorings located between 92 48'E and 88 10'E;
Array ICM3C consists of 7 moorings located between 74 44'E and 69 22'E; and
Array ICM3W consists of 6 moorings located between 52 47'E and 49 23'E.
Approximately 40 CTD/rosette stations will be made along each moored array. Stations
will consist of CTD measurements to the bottom and bottle samples for salinity, nutrients,
and dissolved oxygen. All samples will be analyzed aboard ship.
The mooring work will be directed by members of the Buoy Group at the Oregon State
University. The CTD/rosette work will be directed by representatives of the ODF at SIO.
A conservative estimate is that approximately 34 days of ship time will be required to
carry out the work starting at 20S off the east coast of Madagascar and traveling to
Fremantle, Australia. Transit time from Cape Town to the start of work must be added.
Track segment Distance (n mi)
West end of ICM3W to east end of ICM3E 2520
East end of ICM3E to Perth 1440
Total 3960
Operations Times (hr)
Track underway @ 10 kts 396
Mooring recovery @ 12 hr per mooring 240
39 CTD stations @ 4 hr each 156
Total 792 hrs
33 days
We need the following capabilities:
1) Typical UNOLS outfitting for CTD/rosette work, including CTD winch and cable,
appropriate sheaves, 12 kHz transducer and depth recorder, laboratory space, etc.;
2) A-frame or crane with davit at stern or side - needed to hang a block for retrieving
current meter moorings;
3) Winch and wire (10 km) for full-depth trawling to recover moorings as/if necessary;
4) Support for 15 member scientific party;
5) Underway ADCP and meteorological measurements may be needed; and
6) The most accurate GPS navigation possible for use in locating and recovering moorings.
Clearances will be needed from the Malagasy Republic and France (for Reunion).
Leg 5
David Christie
Oregon State University
Fremantle - Hobart
19 February - 05 March 1997
This leg will be a combination transit from Fremantle to Hobart, as well as an ODP survey.
They will be using 3.5 kHz, SEA BEAM, magnetometer and gravimeter. This survey will
complete data collection in an area of the Southeast Indian Ridge that
was previously surveyed by MELVILLE in February of 1995. A science party of three
or four people is expected. The exact cruise plan is still
to be determined.
Leg 6
Douglas S. Luther
University of Hawaii at Manoa
Hobart - Hobart
08 March - 09 April 1997
Project: U.S.-Australia Cooperative Study of the Northern Branch of the Antarctic
Circumpolar Current
Chief Scientist, Doug Luther, Univ. of Hawaii
Co-P.I.'s:
Jim Richman, OSU
Randy Watts, URI
Alan Chave, WHOI
Jean Filloux, SIO
Science Party - Not determined at this time.
The principal task of this cruise is to recover 9 full-depth current-meter moorings,
and 40 small self-contained seafloor instruments deployed in March-April, 1995, in
an elongated array extending from approximately 47S to 54.5S, 141E to 145E, SSW of
Tasmania. The array spans the northern (strongest) current jet associated with
the Antarctic Circumpolar Current (ACC). The experiment was designed to evaluate
the important momentum and energy balances in the ACC. The experiment also has
goals relating to the intensity and dynamics of the total transport of water and
heat through the array, which are relevant to WOCE objectives.
All the deployed instrumentation will be recalled acoustically. The horizontal
electrometers (18), bottom pressure recorders (4), and inverted echo sounders (18)
all are very small packages (usually a single 17" glass sphere in a plastic hard hat),
requiring reasonably good weather for radio and visual detection when at the surface,
and requiring precision ship maneuvering for pickup.
Depending on the availability of a CTD from our Australian collaborators, we will
collect full-depth CTD profiles over at least the 18 inverted echo sounders before
they are recovered. Time permitting, we will also attempt to complete a high-resolution
CTD section from 54.5S to Tasmania (approximately 25 full-depth CTD profiles), all the
while collecting direct measurements of near-surface currents with the ship's 150 kHz
ADCP, using the Ashtech 3DF GPS receiver for position and heading. The focus of this
CTD/ADCP section is to provide additional information on the strength of the westward
currents just north of our array relative to the eastward currents that exist in the ACC.
Dr. Antony White of Flinders University of South Australia deployed 4 magnetometers
within our electrometer array in April, 1996, and has requested time on this cruise
to recover those instruments. White's request will be accommodated on a time permitting
basis. [While the sub-diurnal electric fields are oceanically induced, the super-diurnal
fields are dominated by ionospherically generated EM waves and can be combined with the
magnetometer data to provide information on the conductivity of the crust and upper
mantle.]
Overhaul
Melbourne, Australia
11 April - 12 May, 1997
MELVILLE will transit from Hobart to Melbourne to undergo a 30 day dry-docking in
Melbourne. We hope to accomplish painting and hull gauging, changing propeller seals, and
perform other routine dry-docking jobs such a pulling the C-valves, which is part of ABS
inspection requirements. The ABS inspection will occur in Melbourne.
Leg 7
Transit
Melbourne- Papeete
08 March - 09 April 1997
Following the overhaul, MELVILLE will transit to Papeete to begin the next and last leg of
the Sojourn Expedition. On the way to Papeete, the ship will collect SEA BEAM in the transit
mode and magnetics.
No other science is currently planned. Clearance will obtained for this portion of survey
from Australia, New Zealand, Tonga, Niue, and France.
Leg 8
Alan Chave
Woods Hole Oceanographic Institution
Papeete- San Diego
29 May- 30 June 1997
The MELT EM experiment is an international collaboration, with foreign participants providing
nearly half of the instrumentation. The purpose of this cruise is to recover approximately
60 seafloor electromagnetic instruments (French, Australian, US, and Japanese) that were
deployed in May- June 1996 from R/V Thompson. These instruments were placed along two lines
at 17oS and 15o45'S on either side of the East Pacific Rise. Five French instruments which
were deployed have backup timers set to release between July 18-22.
Internet: shipsked@ucsd.edu
WWW: http://sio.ucsd.edu/
shipsked@ucsd.edu