HR: 0800h
AN: V21D-0752 [Abstracts]
TI: Spreading Rate Dependence of Hydrothermal Plume Buoyancy Flux at Mid-ocean Ridges
AU: * Zhu, J
EM: jasminezhuj@gmail.com
AF: Department of Geophysics, School of Earth and Space Sciences, Peking University,
Beijing, 100871, China
AU: Lin, J
EM: jlin@whoi.edu
AF: Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods
Hole, MA 02543, United States
AU: Chen, Y J
EM: johnyc@pku.edu.cn
AF: Department of Geophysics, School of Earth and Space Sciences, Peking University,
Beijing, 100871, China
AU: Baker, E T
EM: Edward.Baker@noaa.gov
AF: NOAA, Pacific Marine Environmental Laboratory, Seattle, WA 98115, United States
AB:
We have compiled the plume characteristics of 57 known focused hydrothermal vents along mid-ocean ridges of
full spreading rates from 10 to 150 mm/yr. The calculated vent fluxes show a strong dependence on seafloor
spreading rate. Hydrothermal vents at the fast-spreading northern and southern East Pacific Rise, with full
spreading rates greater than 80 mm/yr, have a relatively narrow range of seafloor depths (2,500 to 2,700 m) and
calculated buoyancy fluxes B0 (10-4 to 10-3 m4/s3). In contrast, at ridges with full
spreading rate less than 80 mm/yr, the seafloor depth of hydrothermal vents varies by a factor of two (<2,000 m
to >4,000 m), while the calculated B0 varies over three orders of magnitude (10-3 to 10-1
m4/s3). The relatively small values of the calculated buoyancy flux and shallow seafloor depth of
individual vents at fast-spreading ridges, together with their relatively narrow range of variations, imply relatively
uniform along-axis distribution of hydrothermal heat release along fast-spreading ridges. This is, in turn, is
consistent with a relatively small variation in both the magma supply and permeability structure at ridge axis along
these fast spreading ridges. In contrast, the much greater ranges in the calculated fluxes and vent depth at slow
and ultraslow spreading ridges reflect significantly greater spatial and temporal variability in heat sources
beneath the ridge axis and more complex tectonic and permeability structure of the oceanic lithosphere.
DE: 1030 Geochemical cycles (0330)
DE: 3001 Back-arc basin processes
DE: 3017 Hydrothermal systems (0450, 1034, 3616, 4832, 8135, 8424)
DE: 4832 Hydrothermal systems (0450, 1034, 3017, 3616, 8135, 8424)
DE: 8430 Volcanic gases
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting