Dive 82-25 with Nivaggioli, Normand and Vincent Renard as the scientist, had
the objective of measuring the growth of the active chimney found during dive
CY82-16, when Harold Bäcker was on board, and revisited during dives CY82-19
and CY82-24. Now that the site was well localized, with a sonar buoy left as a
marker as well as the detailed survey map that had been made, we were able to
organize other dives to return to the exact same area.
In order to measure the growth rate of the newly formed chimney, a device
consisting of a chain of titanium alloy was cleverly constructed by one of the
engineers under the supervision of Guy Sciarrone. The chain consisted of 10 cm
long horizontal bars welded every 20 cm (Fig. 7.21a, b). This would permit the
observers from inside the Cyana (dive 25) to evaluate the dimensions of the target.
On February 19, 1982, during dive Cy 82-25, Pilot Nivaggioli, Co-pilot Normand and Vincent Renard reached their target at 13h25 so they could place the
device for our measuring experiment. Nivaggioli carefully approached the chimney that was spewing hot, black hydrothermal liquid like a locomotive. The
temperature probe inserted on top of the orifice gave a reading of 275 °C. After
replacing the temperature probe in Cyana’s sampling basket, Niva broke off about
25 cm of the black smoker chimney. After securing the piece of chimney inside
the sampling basket of Cyana, he took the graduated chain and laid it on top of the
active orifice. Then he communicated to the surface to share the success of the
operation, which made me very happy. Now they had another 2 h on the bottom to
continue their geological observations and sampling and at 16:23 they returned to
the surface.
February 24, only 5 days later, another dive (Cy 82-30) was programmed to
return to the same site with the same team as on dive Cy 82-25. At 11:00 they
reached the site and it was then that the divers were able to witness the growth of
the chimneys at 2630 m depth with their own eyes. As reported in the diving
report, the co-pilot Arnoux wrote :‘‘All the chimneys seen five days ago have
Fig. 7.21 a Sketch of the graduated chain device made to measure the growth of a hydrothermal
chimney on the sea floor. b On February 19, 1982, a graduated chain device was laid on top of a
‘‘black smoker’’ chimney to visualize the growth rate of a hydrothermal chimney on the axis of
the EPR near 12°50
0 N at 2634 m depth. Five days later the graduate chain was sealed by the
growth of a chimney. (Photo courtesy IFREMER Geocyatherm cruise, Cyana dive Cy82-25)
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7 Oceanic Spreading Ridges and Sea Floor Creation
the objective of measuring the growth of the active chimney found during dive
CY82-16, when Harold Bäcker was on board, and revisited during dives CY82-19
and CY82-24. Now that the site was well localized, with a sonar buoy left as a
marker as well as the detailed survey map that had been made, we were able to
organize other dives to return to the exact same area.
In order to measure the growth rate of the newly formed chimney, a device
consisting of a chain of titanium alloy was cleverly constructed by one of the
engineers under the supervision of Guy Sciarrone. The chain consisted of 10 cm
long horizontal bars welded every 20 cm (Fig. 7.21a, b). This would permit the
observers from inside the Cyana (dive 25) to evaluate the dimensions of the target.
On February 19, 1982, during dive Cy 82-25, Pilot Nivaggioli, Co-pilot Normand and Vincent Renard reached their target at 13h25 so they could place the
device for our measuring experiment. Nivaggioli carefully approached the chimney that was spewing hot, black hydrothermal liquid like a locomotive. The
temperature probe inserted on top of the orifice gave a reading of 275 °C. After
replacing the temperature probe in Cyana’s sampling basket, Niva broke off about
25 cm of the black smoker chimney. After securing the piece of chimney inside
the sampling basket of Cyana, he took the graduated chain and laid it on top of the
active orifice. Then he communicated to the surface to share the success of the
operation, which made me very happy. Now they had another 2 h on the bottom to
continue their geological observations and sampling and at 16:23 they returned to
the surface.
February 24, only 5 days later, another dive (Cy 82-30) was programmed to
return to the same site with the same team as on dive Cy 82-25. At 11:00 they
reached the site and it was then that the divers were able to witness the growth of
the chimneys at 2630 m depth with their own eyes. As reported in the diving
report, the co-pilot Arnoux wrote :‘‘All the chimneys seen five days ago have
Fig. 7.21 a Sketch of the graduated chain device made to measure the growth of a hydrothermal
chimney on the sea floor. b On February 19, 1982, a graduated chain device was laid on top of a
‘‘black smoker’’ chimney to visualize the growth rate of a hydrothermal chimney on the axis of
the EPR near 12°50
0 N at 2634 m depth. Five days later the graduate chain was sealed by the
growth of a chimney. (Photo courtesy IFREMER Geocyatherm cruise, Cyana dive Cy82-25)
220
7 Oceanic Spreading Ridges and Sea Floor Creation