Evidence for an extensive hydrothermal plume in the Tonga-Fiji region of the South Pacific

摘要: [1] Several hydrographic stations in the vicinity of Samoa Islands have 3He/4He above regional background depth range 1500–1800 m, indicating injection mantle helium from a local hydrothermal source. The highest δ(3He) = 43.4% was detected at 1726-m 15.0°S, 173.1°W bathymetric gap between and northern end Tonga-Kermadec Arc. profile this station decreases to 26% 2500-m depth. relatively shallow maximum signal suggests source different conventional Pacific basin plume centered 2500 m that is carried westward East Rise. Stations west locality show progressive decrease values 1480–1790 out 169°E. east Tonga-Fiji region lower 3He (<26%) 1700 profiles are dominated by deeper presumably distal traces input This pattern distribution 1700-m deep northwesterly direction some 2000 km its near At time very little known about or details areal extent. Numerous seamounts rift zones possible sources for plume. summit crater Vailulu'u, young seamount eastern chain, recently discovered be hydrothermally active ∼600 [Hart et al., 2000]. However field on Vailulu'u an unlikely signal. most likely would appear extensional Lau Basin system, such as Mangatolo Triple Junction. Just emanating Lo'ihi has helped our understanding circulation Hawaiian [Lupton, 1996], great potential delineating area south Pacific.