FY 1996

A far-field hydrothermal plume from Loihi Seamount

Lupton, J.E.

Science, 272(5264), 976–979, doi: 10.1126/science.272.5264.976 (1996)

An extensive helium plume in the north central Pacific emanates from Loihi Seamount on the flanks of Hawaii. The maximum helium signal is found at a depth of about 1100 meters, the same depth as the near-field plume directly above Loihi Seamount. Although this helium plume is strongest near Hawaii, where the ³He/⁴He ratio at a depth of about 1100 meters reaches values 28 percent above the atmospheric ratio, it can be detected quite clearly at latitude 24°N, over 400 kilometers to the north. Excess ³He is also present on the same isopycnal between 15°N and 20°N at 135°W, some 2000 kilometers east of the Hawaiian Islands.