Active and relict sea-floor hydrothermal mineralization at the TAG hydrothermal field, Mid-Atlantic Ridge
- National Oceanic and Atmospheric Administration, Miami, FL (United States). Atlantic Oceanographic and Meteorological Labs.
- Geological Survey of Canada, Ottawa, Ontario (Canada)
- Andhra Univ., Visakhapatnam (India)
- Woods Hole Oceanographic Institution, MA (United States)
- Centre des Faibles Radioactivites, Gif-sur-Yvette (France). Lab. CNRS-CEA
- Geological Survey of Canada, Ottawa, Ontario (Canada) Aachen Univ. of Technology (Germany)
The TAG hydrothermal field is a site of major active and inactive volcanic-hosted hydrothermal mineralization in the rift valley of the slow-spreading Mid-Atlantic Ridge at 26[degree]N. The axial high is the principal locus of present magmatic intrusions. The TAG field contains three main areas of present and past hydrothermal activity: (1) an actively venting high-temperature sulfide mound; (2) two former high-temperature vent areas; (3) a zone of low-temperature venting and precipitation of Fe and Mn oxide deposits. The volcanic centers occur at the intersections between ridge axis-parallel normal faults and projected axis-transverse transfer faults. The intersections of these active fault systems may act as conduits both for magmatic intrusions from sources beneath the axial high that build the volcanic centers and for hydrothermal upwelling that taps the heat sources. Radiometric dating of sulfide samples and manganese crusts in the hydrothermal zones and dating of sediments intercalated with pillow lava flows in the volcanic center adjacent to the active sulfide mound indicate multiple episodes of hydrothermal activity throughout the field driven by heat supplied by episodic intrusions over a period of at least 140 [times] 10[sup 3] yr. The sulfide deposits are built by juxtaposition and superposition during relatively long residence times near episodic axial heat sources counterbalanced by mass wasting in the tectonically active rift valley of the slow-spreading oceanic ridge. Hydrothermal reworking of a relict hydrothermal zone by high-temperature hydrothermal episodes has recrystallized sulfides and concentrated the first visible primary gold reported in a deposit at an oceanic ridge.
- OSTI ID:
- 7049433
- Journal Information:
- Economic Geology (plus the Bulletin of the Society of Economic Geologists); (United States), Vol. 88:8; ISSN 0361-0128
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HYDROTHERMAL SYSTEMS
GEOLOGY
ISOTOPE DATING
MID-ATLANTIC RIDGE
GEOLOGIC HISTORY
HEAT FLOW
MINERALOGY
SULFIDE MINERALS
AGE ESTIMATION
ENERGY SYSTEMS
GEOTHERMAL SYSTEMS
MINERALS
150200* - Geology & Hydrology of Geothermal Systems
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