Hydrothermal activity at the TAG hydrothermal field, Mid-Atlantic ridge crest at 26/sup 0/N
The first submersible observations of the only known active submarine hydrothermal field on a slow-spreading oceanic ridge are incorporated with results of 10 prior years of investigation to derive an understanding of periodicity, duration, and varying intensity of hydrothermal activity at the Trans-Atlantic Geotraverse (TAG) Hydrothermal Field on the Mid-Atlantic Ridge crest near latitude 26/sup 0/N. Hydrothermal activity has persisted at this location for a least 1 x 10/sup 6/ years based on the distribution of hydrothermal and hydrogenous mineralization with respect to crustal age. The hydrothermal activity has been cyclic, multistage, and episodic. Prior high-temperature hydrothermal venting stages with a periodicity of the order of 1 x 10/sup 4/ years and duration of the order of 10/sup 1/ years are deduced from the estimated ages of discrete sedimentary layers anomalously enriched in Cu, Fe, and Zn and correspond with the independently determined periodicity of volcanic eruptive cycles on the Mid-Atlantic Ridge. The most recent episode of high-temperature venting is inferred to have ceased in the recent past based on metal enrichment (Cu, Fe, Zn) in the surficial sediment layer. Low-temperature hydrothermal venting stages with a duration of the order of 1 x 10/sup 4/ years intervene between the short high-temperature stages and produce stratiform deposits of layered and earthy manganese oxide, iron oxide, hydroxide and silicate. Bivalve-like forms with the characteristics of vent clams in various stages of dissolution are identified on bottom photographs.
- Research Organization:
- National Oceanic and Atmospheric Administration, Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida
- OSTI ID:
- 6022607
- Journal Information:
- J. Geophys. Res.; (United States), Vol. 89:B13
- Country of Publication:
- United States
- Language:
- English
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