chloritized and show veins of epidote, quartz and sulfides. Fault planes with
subhorizontal slickenside (oriented N 95°-110°) were observed on the outcrops of
the deformed breccia formation.
Diving in the Active Tectonic Zone
The first dive took place in the deepest area of the Garrett Transform’s Active
Tectonic Zone (ATZ). Nautile was put into the sea at 9 AM on January 13, 1991.
Because of the uncertainty of the location, I was anxious about doing this first
dive, along with the pilot, Max Dubois, and the co-pilot, Edmond Toussaint. The
moment of truth was coming soon. We were not sure about whether or not we
would be able to land the submersible on the spot where the R.V. SONNE had
dredged and collected peridotite in 1980. During our communication with the
bridge, we were informed that the current had put us 250 m away from our initial
diving site in the direction 096°N. At 9:09 we started to go down for one of the
longest journeys of my life. Indeed, if you hope to arrive at 5000 m depth, it will
take about 3 h to go down. During our descent we listened to some music and had
had one last briefing before arriving at our destination. When we landed I didn’t
know what I would see through the porthole. Would we be able to re-locate the
dredge site of the FS SONNE and find the exposed peridotite?
At 11h17, at 4933 m depth, we arrived on the sea floor and I started to look out
of the porthole. Max turned the Nautile around in a circle to check the surroundings. At the same time, our eyes were looking on the radar screen to see if
there were any structures in the immediate vicinity or further away. We tested
what we saw on the radar by looking outside through the portholes, first at a
distance of 50 and 100 m, then further to a larger scale of 500 m. There were some
Fig. 8.4 Landslide of large
dolerite and basalt blocks on
the slope of the Garrett
Transform’s northern wall at
3602 m depth observed from
the submersible. Note a
polygonal block of a dyke in
the center of photo
(Copyright IFREMER,
Garrett cruise 1991, Nautile
dive GN16)
The Transform Fault’s Active Tectonic Zone
263
subhorizontal slickenside (oriented N 95°-110°) were observed on the outcrops of
the deformed breccia formation.
Diving in the Active Tectonic Zone
The first dive took place in the deepest area of the Garrett Transform’s Active
Tectonic Zone (ATZ). Nautile was put into the sea at 9 AM on January 13, 1991.
Because of the uncertainty of the location, I was anxious about doing this first
dive, along with the pilot, Max Dubois, and the co-pilot, Edmond Toussaint. The
moment of truth was coming soon. We were not sure about whether or not we
would be able to land the submersible on the spot where the R.V. SONNE had
dredged and collected peridotite in 1980. During our communication with the
bridge, we were informed that the current had put us 250 m away from our initial
diving site in the direction 096°N. At 9:09 we started to go down for one of the
longest journeys of my life. Indeed, if you hope to arrive at 5000 m depth, it will
take about 3 h to go down. During our descent we listened to some music and had
had one last briefing before arriving at our destination. When we landed I didn’t
know what I would see through the porthole. Would we be able to re-locate the
dredge site of the FS SONNE and find the exposed peridotite?
At 11h17, at 4933 m depth, we arrived on the sea floor and I started to look out
of the porthole. Max turned the Nautile around in a circle to check the surroundings. At the same time, our eyes were looking on the radar screen to see if
there were any structures in the immediate vicinity or further away. We tested
what we saw on the radar by looking outside through the portholes, first at a
distance of 50 and 100 m, then further to a larger scale of 500 m. There were some
Fig. 8.4 Landslide of large
dolerite and basalt blocks on
the slope of the Garrett
Transform’s northern wall at
3602 m depth observed from
the submersible. Note a
polygonal block of a dyke in
the center of photo
(Copyright IFREMER,
Garrett cruise 1991, Nautile
dive GN16)
The Transform Fault’s Active Tectonic Zone
263