Two other dives (PN 11 and PN 12) on the Bounty were devoted to testing a
laser deep-sea probe device for the first time at sea, under the responsibility of
Dr. Arthur Lane, an engineer from the Jet Propulsion Laboratory (JPL) of
Pasadena California. The instrument designed at JPL was supposed to be able to
detect and record spectral or fluorescent signatures of bio-luminescent life and
minerals. This preliminary deep-sea experiment was intended to gather data under
the extreme conditions of a high-pressure environment. This was a stepping-stone
to the further development of a prototype that could eventually penetrate the ice
caps of Mars or explore other extraterrestrial oceans in search of life, such as on
the surface of Europa, one of Jupiter’s moons. Dr. Lane was a short man with
white and gray hair, glasses and a small beard. He often wore a worried expression
since he was probably thinking about the outcome of his experiment. Indeed, a
failure of the experiment could jeopardize his entire project. He was also a
practicing Jew, so he honored the ‘‘Sabbath’’ meaning he refused to dive or work
on Saturday. He used to spend most of his time in his cabin. Our chief scientist,
Jacques Dubois, in respect for Dr Lane’s beliefs, had to re-schedule his dive for
another day. Dr. Lane made two consecutive dives on September 9 and 10.
Luckily, his experiments went well, since he was able to penetrate his probe into
the hydrothermal field and make appropriate measurements.
The last dive on Bounty, PN14, took place on September 13, 1999 and was
aimed at continuing the profile of dive PN03 which had also been performed by
Chrystèle Guivel. The dive reached the bottom at 11:19 (local time) at 1890 m
depth near where her previous dive had stopped. Since Chrystèle had the experience of dive PN03 and was therefore familiar with the landscape, she was able to
pick up where she had left off. As on the previous dives, they observed a succession of lava flow and volcanic debris in the form of ash and fragments of
pyroclasts. This was the last dive on the Pitcairn hotspot so the ship moved to the
next target, which was dedicated to the Teahitia hotspot in the Society region.
Dives on Bounty Volcano: Volcanic Stratigraphy
The main goal of the dives conducted on the Bounty Volcano was to be able to
show that continuous sequential volcanism is responsible for building the tall
hotspot edifices on the sea floor. Although the identification of sequential volcanic
activities has been observed on subaerial volcanoes, it was never before done for
volcanoes on the deep seafloor. Geological observations were made during five
dives (PN03, 06, -04, -12, and -14) along the slope of a large volcanic edifice, the
Bounty Volcano (Fig. 9.18a, b).
Along the dive profiles that were reconstructed from observations on the
western flank of the Bounty volcano, at least nine volcanic sequences (units) have
been recognized. Each of these units varies from about 50 to about 500 m thick
and averages about 300 m in thickness. Each volcanic unit is constructed with a
succession of high temperature ([1100 °C) events giving rise to basalt and
336
9 Hotspots
laser deep-sea probe device for the first time at sea, under the responsibility of
Dr. Arthur Lane, an engineer from the Jet Propulsion Laboratory (JPL) of
Pasadena California. The instrument designed at JPL was supposed to be able to
detect and record spectral or fluorescent signatures of bio-luminescent life and
minerals. This preliminary deep-sea experiment was intended to gather data under
the extreme conditions of a high-pressure environment. This was a stepping-stone
to the further development of a prototype that could eventually penetrate the ice
caps of Mars or explore other extraterrestrial oceans in search of life, such as on
the surface of Europa, one of Jupiter’s moons. Dr. Lane was a short man with
white and gray hair, glasses and a small beard. He often wore a worried expression
since he was probably thinking about the outcome of his experiment. Indeed, a
failure of the experiment could jeopardize his entire project. He was also a
practicing Jew, so he honored the ‘‘Sabbath’’ meaning he refused to dive or work
on Saturday. He used to spend most of his time in his cabin. Our chief scientist,
Jacques Dubois, in respect for Dr Lane’s beliefs, had to re-schedule his dive for
another day. Dr. Lane made two consecutive dives on September 9 and 10.
Luckily, his experiments went well, since he was able to penetrate his probe into
the hydrothermal field and make appropriate measurements.
The last dive on Bounty, PN14, took place on September 13, 1999 and was
aimed at continuing the profile of dive PN03 which had also been performed by
Chrystèle Guivel. The dive reached the bottom at 11:19 (local time) at 1890 m
depth near where her previous dive had stopped. Since Chrystèle had the experience of dive PN03 and was therefore familiar with the landscape, she was able to
pick up where she had left off. As on the previous dives, they observed a succession of lava flow and volcanic debris in the form of ash and fragments of
pyroclasts. This was the last dive on the Pitcairn hotspot so the ship moved to the
next target, which was dedicated to the Teahitia hotspot in the Society region.
Dives on Bounty Volcano: Volcanic Stratigraphy
The main goal of the dives conducted on the Bounty Volcano was to be able to
show that continuous sequential volcanism is responsible for building the tall
hotspot edifices on the sea floor. Although the identification of sequential volcanic
activities has been observed on subaerial volcanoes, it was never before done for
volcanoes on the deep seafloor. Geological observations were made during five
dives (PN03, 06, -04, -12, and -14) along the slope of a large volcanic edifice, the
Bounty Volcano (Fig. 9.18a, b).
Along the dive profiles that were reconstructed from observations on the
western flank of the Bounty volcano, at least nine volcanic sequences (units) have
been recognized. Each of these units varies from about 50 to about 500 m thick
and averages about 300 m in thickness. Each volcanic unit is constructed with a
succession of high temperature ([1100 °C) events giving rise to basalt and
336
9 Hotspots