Geologic setting of the Snake Pit hydrothermal site: An active vent field on the Mid-Atlantic Ridge

Jeffrey A. Karson, Jennifer R. Brown

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


The Snake Pit Hydrothermal Site lies on the axis of the Mid-Atlantic Ridge at 23°22′ N latitude, about 30 km south of the Kane Transform Intersection. Active 'black smoker' vents and a surrounding field of hydrothermal sediment occur at the crest of a laterally extensive neovolcanic ridge. It is one of the first active hydrothermal vent fields to be found on a slow-spreading ridge axis and despite significant differences in its geologic setting from those of the East Pacific Rise, has many similarities to its fast-spreading counterparts. Although preliminary reports have documented many interesting aspects of these vents and their surroundings, new data collected from the manned submersible ALVIN and the deep-towed ANGUS camera system define the regional tectonic setting as well as the local geologic environment of this fascinating area. The Snake Pit vents are located on a local peak of a volcanic constructional ridge at a depth of 3450 m, 700-800 m deeper than vents known from the East Pacific Rise, Galapagos, or Juan de Fuca spreading centers. The vent field is at least 600 m long and up to 200 m wide and is covered by a thick blanket of greenish to yellow-orange hydrothermal sediment. Both active and extinct vents are perched along the crests of steep-sided sulfide mounds that reach heights of over 40 m. High-temperature (350° C) fluids are vented from black smoker chimneys and low-temperature (226° C) fluids seep from sulphide domes and subordinate anhydrite constructions. Water temperatures, flow rates, fluid chemistries, and mineralization are strikingly similar to vents of faster spreading ridge crests; however, a somewhat distinct fauna inhabit the area.

Original languageEnglish (US)
Pages (from-to)91-107
Number of pages17
JournalMarine Geophysical Researches
Issue number1-2
StatePublished - Mar 1988
Externally publishedYes


  • Hydrothermal vents
  • Mid-Atlantic Ridge
  • Snake Pit
  • seafloor spreading

ASJC Scopus subject areas

  • Oceanography
  • Geophysics
  • Geochemistry and Petrology


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