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AHA Field

Name Alias(es): 
1 44'N, EPR
MGDS_FeatureID lowest in hierarchy: 
Vent Sites: 
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Maximum or Single Reported Depth (mbsl): 
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Full Spreading Rate (mm/a): 
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Notes on Vent Field Description: 
Shank et al. (2000): "Several vent fields were dominated by diffuse fluid venting from fissures and cracks on the southwestern edge of a large volcanic mound and along the axial trough, where young lava flows were present. Diffuse hydrothermal activity at the newly-discovered vent sites appeared to be extensive: up to ~1000m2. Black smoker chimneys were not observed."
Notes Relevant to Biology: 
Shank et al. (2000): "Vent faunal communities were dominated by Stauromedusae (Scyphozoa, Cnidaria). These animals were abundant (at times having densities over 20 indiv. per square meter) and were commonly attached to the sides of fissures and cracks where diffuse, milky fluids were venting or on the surface of the glassy lava flows. Clusters of white, translucent stalked scyphozoans were frequently bordered by pinkish anemones. Clumps of vestimentiferan tube worms (Riftia and Tevnia) typical of northern EPR vent communities were prevalent around areas where venting was concentrated. Large vesicomyid clam assemblages (Calyptogena aff.) were frequently observed, however the majority of individuals appeared to be dead, with shells disarticulated and broken. Mobile megafauna included brachyuran and galatheid crabs."
Year and How Discovered (if active, visual confirmation is listed first): 
2000 towed imaging ARGO-II
Discovery References (text): 
Shank et al., Biology of Newly-Discovered "AHA" Hydrothermal Vent Fields Near 1 44'N on the East Pacific Rise Axis, EOS Trans. AGU, 81 (48), Fall Meet. Suppl., Abstract T51D-15, 2000.
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