Chemical and mineral compositions of sulfide deposits from the Snake Pit hydrothermal field, Mid-Atlantic Ridge rift zone

The Snake Pit hydrothermal field is located on the top of a neovolcanic rise on the Mid-Atlantic Ridge at sea depths between 3460 and 3510 m. It was surveyed during several oceanological expeditions including DSDP Legs. Additional scientific materials were obtained in 2002 and 2003 during expedition onboard R/V Akademik Mstislav Keldysh with two Mir deep-sea manned submersibles. Three eastern hydrothermal mounds (Moose, Beehive, and Fir Tree) are located on the upper part of the eastern slope of the rise over a common fractured pedestal composed of fragments of massive sulfides. The western group of hydrothermal deposits is encountered on the western slope of the axial graben. Within this mature hydrothermal field, which was formed over the past 4000 years, we studied morphology of the hydrothermal mounds, chemistry and mineralogy of hydrothermal deposits, chemistry of sulfide minerals, and isotope composition of sulfur in them.

Chemical and mineral compositions of hydrothermal sulfide deposits from the Lucky Strike hydrothermal field, Mid-Atlantic Ridge

Several hydrothermal sulfide structures were sampled using the Mir manned submersibles in the relatively shallow Lucky Strike vent field, Mid-Atlantic Ridge. Bathymetric position of these structures varies by approximately 100 m. Investigation of chemical and mineral compositions of hydrothermal ore occurrences led to the conclusion that the initial high-temperature ore-bearing solution ascending toward the surface became unstable and experienced phase separation beneath the ocean floor. The phase separation was responsible for bathymetric control of hydrothermal ore formation within the field.