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nism along the zone of crustal accretion, constrain the physical
and chemical characteristics and temporal evolution of hydrothermal
activity, and investigate their effect on geo-microbiological
interactions. Cruise MOMARSAT (PIs M. Cannat, J.
Blandin and P.-M. Sarradin), pre-scheduled for 2010, will be a
demonstration mission of the ESONET Network of Excellence
supported by the European Union. The project aims to deploy
an acoustically-linked multidisciplinary observing system at
the Lucky Strike vent field, with satellite connection to shore,
marking the first step toward the installation of a permanent
observatory in the MOMAR area.
Other cruises completed in 2008 or planned for
2009 and 2010
An important experiment that was completed in 2008 is the recovery
of the three hydrophones moored in the SOFAR channel
in the Indian Ocean as part of the project DEFLO-HYDR
(PI Jean Yves Royer). Two hydrophones were recovered by R/V
Marion Dufresne during a scientific cruise of the French Polar
Institute (IPEV), and the third by the same ship during a
logistical tour of the French Austral and Antarctic Territories
(TAAF). The data collected by these instruments are currently
being analyzed.
In the beginning of 2009, project OHA-SIS-BIO (PI Jean Yves
Royer) will redeploy these hydrophones with R/V Marion Dufresne
in order to monitor (1) the earthquake activity associated
with the three contrasted Indian ridges and the intraplate deformation
zone in the Central Indian Basin, and (2) the vocal
activity of marine mammals such as large whales to improve
our knowledge on their presence, abundance, and migration
patterns.
In the same area, cruise GEISEIR (PI Christophe Hémond),
scheduled for Jan. - Feb. 2009 on R/V Marion Dufresne, will
collect dredged and wax-cored samples on selected sections
of the Southeast Indian Ridge (SEIR) in order to investigate
the isotopic heterogeneities observed along this ridge and the
dynamics of the underlying mantle. The samples will enable
further testing of the hypothesis that the unique isotopic pattern
observed along the SEIR reveals striations between ancient
mantle sources and recycled material. This cruise also offers
a unique opportunity to collect bathymetric and geophysical
data in a remote ridge section, in complement to several previous
American cruises.
The SMOOTHSEAFLOOR project (PIs Daniel Sauter and
Mathilde Cannat) aims to better constrain the composition,
structure, magnetic signature and mode of formation of the
“smooth seafloor” domains described during a previous cruise
on the Southwest Indian Ridge. These domains may have been
formed with no or very little volcanic activity and probably
expose exhumed mantle rocks with an undetermined proportion
of magmatic intrusives. The proposal was ranked highly
and may be scheduled in the end of 2009 on R/V Marion Dufresne.
A set of three cruises is scheduled or pre-scheduled in the Pacific
Ocean for the end of 2009 and the beginning of 2010, onboard
R/V L’Atalante with the submersible Nautile and AUV
ASTER X . This long-awaited event underlines the continuous
interest of the French community for the area, despite logistical
and financial difficulties which prevented earlier scheduling.
Cruise PARISUB (PI Pascal Gente) will achieve a detailed
investigation of the interaction between a plume, the Mathematicians
hotspot, and a spreading axis, the East Pacific Rise
(EPR) at 16°N. Cruise MESCAL (PIs François Lallier and
Nadine Le Bris) on the EPR at 9, 11, and 13°N will focus on
two themes: (a) the colonization strategies and adaptation of
Alvinella pompejana to thermal and chemical stresses, and (b)
the integrative biology of thiotrophic endosymbiosis. Cruise
BIG (PI Anne Godfroy) in the Guaymas Basin, which displays
both hydrothermal and cold seep sites, will characterize the
physicochemical gradients and the microbial and faunal communities
along these gradients to evaluate the taxonomical and
functional similarities within the two habitats.
Germany
Colin Devey
The German ridge program entered its final year in September
2008. Of the three cruises still planned for the final year, one
(to be lead by Ingo Grevemeyer and concentrating on active
and passive seismic studies of the Logatchev area) has unfortunately
been cancelled due to new propulsion problems with the
vessel Maria S. Merian. Juggling of other cruise schedules and
piggy-backing of some experiments will hopefully allow us to
nevertheless rescue a large portion of the science scheduled to
be carried out on that cruise. (continued on next page)
InterRidge News 33 Vol. 17, 2008