MoMAR observatory: A Geophysical, Geological and Oceanographical Approach to the Monitoring of the Lucky Strike Segment (GRAVILUCK Cruise)
Abstract
The GRAVILUCK expedition, conducted in August 2006 on the R/V ATALANTE, was mainly dedicated to the installation of a seafloor geodetic network in the framework of the MoMAR ("Monitoring the Mid-Atlantic Ridge") project, to study active mid-ocean ridge processes along a slow-spreading ridge segment. The chosen site for this integrated "observatory" effort is the Lucky Strike segment (37°N) along the Mid-Atlantic Ridge, South of the Azores Archipelago; it combines both logistic and scientific interests, and has been studied in depth by geologists, geophysicists and biologists for many years. It also presents an intense hydrothermal activity and hosts an axial magma chamber under its center discovered last year during the SISMOMAR cruise. The installation of 9 permanent geodetic benchmarks and the time-zero pressure and gravity measurements were conducting during 19 Nautile dives. Pressure changes measured at a benchmark can be due to environmental variability, to a change in the elevation of the point, or to both. To quantify environmental variations, we monitored water column with full depth CTD prior to each dive, and shallow CTD yoyos down to 500 m during the dives. These oceanographic measurements will allow us to directly model and remove part of the environmental variability and thus increase our capability to detect small vertical motions over several years. Three additional Nautile dives were dedicated to geology and gravity cartography of the central volcano. In addition to the day program, 10 nights were devoted to a geological survey using the TowCam (camera, magnetometer, wax coring, CTD) to characterize tectonic and magmatic features of the Lucky Strike volcano, their relationship to the magma chamber location, and identification of areas of most recent apparent volcanic activity; 10 other nights were dedicated to studying ocean circulation and induced mixing around the Lucky Strike site. GRAVILUCK cruise Scientific Party: CNRS/IPGP: J. Ammann, V. Ballu, M. Cannat, C. Deplus, J. Escartin, O. Pot, C. Rommevaux-Jestin; IPGP: C. Cadio, S. Deroussi, M. Kitazawa; CNRS/INSU: G. Duveau, C. Marec; Univ. Açores: I. Bashmachnikov; Harvard Univ.: A. Bezos; IGN: MN. Bouin; FSU: E. Howarth, L. St Laurent; CNRS/UBO: M. Maia; LOCEAN: P. Bouruet-Aubertot, A. Lourenço, G. Reverdin; SIO: G. Sasagawa; WHOI: S. A. Soule; LDEO: A. Thurnherr.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFMOS31B1635B
- Keywords:
-
- 1200 GEODESY AND GRAVITY;
- 1217 Time variable gravity (7223;
- 7230);
- 3045 Seafloor morphology;
- geology;
- and geophysics;
- 3050 Ocean observatories and experiments;
- 8416 Mid-oceanic ridge processes (1032;
- 3614)