on February 26, at the ‘‘Bryce Canyon’’ site where he sampled hydrothermal fluid
from an active black smoker.
During the two legs of the cruise, 32 submersible dives were made plus there
were other surface-ship stations at night.
During the second Leg of the cruise we met up with the German vessel, the F.S.
SONNE, which had arrived in the area around February 2, to conduct geological
exploration from the surface. I communicated with the chief scientist, Harold
Bäcker from Preussag, a mining company in Germany, and he asked me if it would
be possible to participate on one of our dives. Knowing Harold’s reputation as a
conscientious and internationally known marine geologist, I accepted his request
after consulting with the captain and Jean Roux who was responsible for the
submersible group.
Harold arrived on board and after an evening’s briefing he was ready to dive the
next morning. It was during dive Cy 82-16 on January 4, 1982, that Harold Bäcker
with the pilots Arnoux and Pottier, discovered an important field of several active
hydrothermal chimneys at the foot of a lava pond in the axial graben near 12°50
0 N.
This dive was the first of a series of dives planed to carry out a systematic visual
survey across the spreading axis in order to make the first geological map of the
seafloor using a submersible. We intended to make several transects, at least six
from wall to wall and perpendicular to the spreading axis where the freshest lava
and the most active hydrothermal vents occurred.
Harold and the pilot and co-pilot arrived on the sea floor at 10:15 at a depth of
2610 m at the foot of the east graben wall. After few minutes for positioning the
submarine with respect the transponder, they took a westerly course (2708). They
crossed a lava pond 30 m away from the landing site and collected their first rock
sample coated with rusty colored hydrothermal deposits. Above the lava pond,
they found a hydrothermal chimney spewing white, low temperature (47 °C) fluid
(a ‘‘white smoker’’). A few other inactive chimneys were crossed and then they
returned to make another crossing after reaching the west wall’s first scarp. After
the third crossing from wall to wall, they arrived on a very active hydrothermal
field spewing out black, high-temperature fluid. When the temperature probe was
put at the interface between the solid metallic orifice of the chimney and the
exiting dark fluid, the temperature reading reached 232 °C. A sulfide sample was
taken near the active chimney at 14h52 at 2,616 m depth. After that, the diving
party spent about one hour on the site and at 15h02 they left to terminate their
crossing and reached the western wall’s first scarp about 15 min later. At this
point, it was time to leave the bottom.
At that time, the divers did not realize that they had found a hydrothermal field
that would become a natural laboratory where geochemical and biological
instruments could be deployed during several future cruises. Harold Bäcker, for
whom this was his first submersible dive, was very enthusiastic about what he saw
and was extremely grateful for having been able to observe the sea floor for the
first time with his own eyes.
The next three dives (Cy 82-17, Cy 82-18 and Cy 82-19 on February 5th, 6th
and 7th) were also planned to use the same transponder network which had been
216
7 Oceanic Spreading Ridges and Sea Floor Creation
from an active black smoker.
During the two legs of the cruise, 32 submersible dives were made plus there
were other surface-ship stations at night.
During the second Leg of the cruise we met up with the German vessel, the F.S.
SONNE, which had arrived in the area around February 2, to conduct geological
exploration from the surface. I communicated with the chief scientist, Harold
Bäcker from Preussag, a mining company in Germany, and he asked me if it would
be possible to participate on one of our dives. Knowing Harold’s reputation as a
conscientious and internationally known marine geologist, I accepted his request
after consulting with the captain and Jean Roux who was responsible for the
submersible group.
Harold arrived on board and after an evening’s briefing he was ready to dive the
next morning. It was during dive Cy 82-16 on January 4, 1982, that Harold Bäcker
with the pilots Arnoux and Pottier, discovered an important field of several active
hydrothermal chimneys at the foot of a lava pond in the axial graben near 12°50
0 N.
This dive was the first of a series of dives planed to carry out a systematic visual
survey across the spreading axis in order to make the first geological map of the
seafloor using a submersible. We intended to make several transects, at least six
from wall to wall and perpendicular to the spreading axis where the freshest lava
and the most active hydrothermal vents occurred.
Harold and the pilot and co-pilot arrived on the sea floor at 10:15 at a depth of
2610 m at the foot of the east graben wall. After few minutes for positioning the
submarine with respect the transponder, they took a westerly course (2708). They
crossed a lava pond 30 m away from the landing site and collected their first rock
sample coated with rusty colored hydrothermal deposits. Above the lava pond,
they found a hydrothermal chimney spewing white, low temperature (47 °C) fluid
(a ‘‘white smoker’’). A few other inactive chimneys were crossed and then they
returned to make another crossing after reaching the west wall’s first scarp. After
the third crossing from wall to wall, they arrived on a very active hydrothermal
field spewing out black, high-temperature fluid. When the temperature probe was
put at the interface between the solid metallic orifice of the chimney and the
exiting dark fluid, the temperature reading reached 232 °C. A sulfide sample was
taken near the active chimney at 14h52 at 2,616 m depth. After that, the diving
party spent about one hour on the site and at 15h02 they left to terminate their
crossing and reached the western wall’s first scarp about 15 min later. At this
point, it was time to leave the bottom.
At that time, the divers did not realize that they had found a hydrothermal field
that would become a natural laboratory where geochemical and biological
instruments could be deployed during several future cruises. Harold Bäcker, for
whom this was his first submersible dive, was very enthusiastic about what he saw
and was extremely grateful for having been able to observe the sea floor for the
first time with his own eyes.
The next three dives (Cy 82-17, Cy 82-18 and Cy 82-19 on February 5th, 6th
and 7th) were also planned to use the same transponder network which had been
216
7 Oceanic Spreading Ridges and Sea Floor Creation