HR: 1340h
AN: OS33A-1464 [Abstracts]
TI: Saldanha Massif, Mid-Atlantic Ridge: A Controlled Source EM Study
AU: * Sinha, M C
EM: sinha@noc.soton.ac.uk
AF: National Oceanography Centre Southampton, European Way, Southampton, SO15 7PN
United Kingdom
AU: Santos, F
EM: fasantos@fc.ul.pt
AF: Universidade de Lisboa, Faculdade de Ciˆncias
Edif. C8, Lisboa, 1749-016
Portugal
AU: Dzhatieva, Z
EM: zald@noc.soton.ac.uk
AF: Universidade de Lisboa, Faculdade de Ciˆncias
Edif. C8, Lisboa, 1749-016
Portugal
AU: Dias, A
EM: adias@fc.ul.pt
AF: Universidade de Lisboa, Faculdade de Ciˆncias
Edif. C8, Lisboa, 1749-016
Portugal
AU: Marques, A F
EM: afamarques@fc.ul.pt
AF: Universidade de Lisboa, Faculdade de Ciˆncias
Edif. C8, Lisboa, 1749-016
Portugal
AU: Silva, N
EM: nsilva@fc.ul.pt
AF: Universidade de Lisboa, Faculdade de Ciˆncias
Edif. C8, Lisboa, 1749-016
Portugal
AU: Denijs, I
EM: igorgonz@noc.soton.ac.uk
AF: National Oceanography Centre Southampton, European Way, Southampton, SO15 7PN
United Kingdom
AB:
In November-December 2004 a controlled source electromagnetic (CSEM) survey was carried out on the axis of the Mid-Atlantic
Ridge during cruise Charles Darwin 167. The work is centred on a non-transform offset between the FAMOUS and AMAR segments,
at 36 34' North. Here, a prominent feature is the Saldanha massif: a dome of unroofed mantle rocks, consisting largely of
serpentised peridotites, and at whose summit significant low-temperature hydrothermal venting has been documented. Our
objective is to determine the distribution of electrical resistivity and hence porosity over a volume of ~ 10 km x 10 km x 3
km vertically, in order to constrain the degree of penetration of seawater into the crust and uppermost mantle; to contrast
the porosity structure here with volcanically hosted systems away from segment boundaries elsewhere on the MAR; and to
constrain models of non-volcanic heat sources and hydrothermal circulation in ultramafic settings at slow spreading ridges.
In addition to the CSEM survey we obtained swath bathymetry, gravity and magnetic data; water column physical properties and
seafloor current data; and a number of dredge and gravity core samples. We shall present details of the data and samples,
together with our preliminary analysis of the results.
DE: 0699 General or miscellaneous
DE: 0930 Oceanic structures
DE: 3006 Marine electromagnetics
DE: 3017 Hydrothermal systems (0450, 1034, 3616, 4832, 8135, 8424)
DE: 3035 Midocean ridge processes
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005