Fig. 6.5 Five photos (copyright IFREMER Geocyarise cruise 1984, Cyana dives Cy84-07,
Cy84-24, and Geocyatherm cruise 1982, Cyana dive Cy82-35.) showing the construction and
evolution of a hydrothermal field. a Early formation of an active hydrothermal field with the exit
of clear warm water throughout a fissured lava flow. A small biological community starts to
develop, as seen during dive Cy82-07 at 2525 m depth on the EPR near 11°27
0 N. b Luxuriant
biological community of tubeworms associated with the early construction of a hydrothermal
sulfide edifice during the precipitation of high temperature (250 °C) to moderate temperature
(150 °C) deposits. Example shown was seen during dive Cy82-35 at 2623 m depth on the EPR
near 12°50
0 N. c Stage of intense hydrothermalism with the exit of high temperature ([200 °C)
fluid and the construction of polymetallic sulfide edifices seen during dive Cy82-07 at 2530 m
depth on the EPR near 11°27
0 N and d Late, waning stage of hydrothermal activity with the
decrease of hydrothermal fluid flow as observed during dive Cy84-24 on a multiple chimney
located on the EPR’s eastern wall at about 3 km from the graben’s axis near 12°43
0 S at 2572 m
depth. e Dislocated and altered dead hydrothermal chimney seen during dive Cy84-24 at 2582 m
depth on the eastern wall of the EPR axis near 12°43
0 N
Phases Forming Hydrothermal Deposits
161
Cy84-24, and Geocyatherm cruise 1982, Cyana dive Cy82-35.) showing the construction and
evolution of a hydrothermal field. a Early formation of an active hydrothermal field with the exit
of clear warm water throughout a fissured lava flow. A small biological community starts to
develop, as seen during dive Cy82-07 at 2525 m depth on the EPR near 11°27
0 N. b Luxuriant
biological community of tubeworms associated with the early construction of a hydrothermal
sulfide edifice during the precipitation of high temperature (250 °C) to moderate temperature
(150 °C) deposits. Example shown was seen during dive Cy82-35 at 2623 m depth on the EPR
near 12°50
0 N. c Stage of intense hydrothermalism with the exit of high temperature ([200 °C)
fluid and the construction of polymetallic sulfide edifices seen during dive Cy82-07 at 2530 m
depth on the EPR near 11°27
0 N and d Late, waning stage of hydrothermal activity with the
decrease of hydrothermal fluid flow as observed during dive Cy84-24 on a multiple chimney
located on the EPR’s eastern wall at about 3 km from the graben’s axis near 12°43
0 S at 2572 m
depth. e Dislocated and altered dead hydrothermal chimney seen during dive Cy84-24 at 2582 m
depth on the eastern wall of the EPR axis near 12°43
0 N
Phases Forming Hydrothermal Deposits
161