Full version, lower resolution, 3.25MB - InterRidge

National News
cruise in Aug. - Sept. 2008 on board the Chinese R/V DayangYihao
to the SEPR near the equator. As the continuation
of the successful collaboration between the Second Institute
of Oceanography, SOA, China, and WHOI in exploring the
Southwest Indian Ridge in 2007, the recent joint cruise was
also equipped with WHOI’s autonomous underwater vehicle
ABE. This expedition follows the work of a 2005 expedition
by R/V DayangYihao, during which strong water column turbidity
anomalies were measured in the region. Several new
high-temperature hydrothermal vent fields were discovered
along the SEPR ridge axis and on an off-axis seamount located
between 1.4°S to 2.2°S. A significant portion of the hydrothermal
activity at the ridge axis appears to be concentrated along
the edges of a seafloor fissure system. High-resolution bottom
bathymetry, deep-tow magnetics, color photography, water
column data, as well as hydrothermal sulfide deposit samples
Among the upcoming cruises already planned for the MO-
MAR area, cruise BATHYLUCK (PIs Javier Escartin and
Anne Deschamps), scheduled for summer 2009 on R/V Pourquoi
pas? with ROV Victor, is an integrated, multi-scale study of
the Lucky Strike hydrothermal field and its setting. The project
aims to understand the interplay between tectonics and volcawere
obtained during the cruise. An abstract was submitted at
sea and preliminary results of major findings of this cruise will
be reported at the Fall AGU Meeting in San Francisco, 15-19
December 2008.
Expedition to the Southwest Indian Ridge
R/V DayangYihao will conduct a few legs of investigation of
the SWIR near 49.5°E, where the first active high-temperature
hydrothermal vent field of the SWIR was discovered in Feb.
- March 2007 (see Tao et al., InterRidge News, 2007). These
legs will occur in late 2008 - early 2009 and will include microbiological
sampling and further investigation of the active
hydrothermal vent field and seafloor geology. Furthermore, a
seismic experiment using ocean bottom seismometers is being
planned for this part of the SWIR for the late 2009 - early
2010 field season.
France
Jérôme Dyment
Mid-ocean ridge studies in France are either part of the MO-
MAR project, which plays a central role in focusing efforts at a
national scale, or individual cruise projects:
MOMAR
In 2007, the two diving cruises planned on hydrothermal vents
Rainbow and Lucky Strike were shortened and postponed due
to technical problems with ROV Victor and R/V Pourquoi pas?.
Only nine dives of the submersible Nautile, mostly devoted to
the collection of biological and rock samples, were achieved on
site Rainbow as part of the MOMARDREAM experiment (see
InterRidge News, 2007). The experiments that could not take
place in 2007 were rescheduled to August and September 2008
onboard R/V L’Atalante with ROV Victor.
During cruise MOMAR 08 Leg 1 on site Lucky Strike (Aug.
9-24, Chief Scientist Javier Escartin), two pressure gauges, as
part of the GRAVILUCK experiment (PI Valerie Ballu), and
the TEMPO module, as part of the EXOCET/D project (PI
Pierre-Marie Sarradin), were recovered. The initial part of the
BATHYLUCK experiment (PI Javier Escartin) involved the
deployment of temperature sensors and geo-microbiological
experimentation. The detailed micro-bathymetric survey of the
Lucky Strike volcano, started during cruise MOMARETO in
2006, was significantly extended during this cruise.
Cruise MOMAR 08 Leg 2 on site Rainbow (Aug. 25 - Sept.
15, Chief Scientist Jérôme Dyment) was the second and final
part of the MOMARDREAM experiment. This leg conducted
micro-bathymetric, magnetic, and high resolution photographic
surveys over the site and surrounding areas. Chemical
and physical parameters were measured over selected vent sites,
where fauna were also collected (including Rimicaris exoculata
and Bathymodiolus azoricus). Fluids were taken for the study of
abiogenic organic compounds. In addition, a large collection of
various rocks was dredged over Rainbow.
A third cruise, BBMOMAR 2 of R/V Le Suroît, (Aug. 8-17,
Chief Scientist Wayne Crawford) was devoted to the recovery
and (re)deployment of Ocean Bottom Seismometers (OBS) on
the Lucky Strike segment. After this cruise, thanks to the addition
of Portuguese OBSs to be recovered in fall 2008 by a Portuguese
ship, more than 15 OBSs are collecting seismological
data to describe precisely the seismicity of the segment.
Finally, a fourth cruise, MARCHE 3 of R/V Almirante Gago
Coutiñho (a Portuguese vessel; Aug. 13-20, Chief Scientists
Jean Goslin, Nuno Lourenço, Bob Dziak) recovered four hydrophones
moored in the SOFAR channel south of the Azores.
The data collected by these instruments are essential to determine
the seismicity over a large section of the Mid-Atlantic
Ridge south of the Azores, including the Lucky Strike and
Rainbow areas (see article by Goslin et al., this volume).
InterRidge News 32 Vol. 17, 2008