HR: 0800h
AN: T41C-1324    [Abstracts]
TI: Estimates of Ridge-Axis Heat Flow from Depth and Age Data
AU: * Wei, M
EM: mwei@ucsd.edu
AF: Scripps Institution of Oceanography, Scripps Institution of Oceanography University of California, San Diego 9500 Gilman Drive, La Jolla, CA 92093-0225 United States
AU: Sandwell, D
EM: dsandwell@ucsd.edu
AF: Scripps Institution of Oceanography, Scripps Institution of Oceanography University of California, San Diego 9500 Gilman Drive, La Jolla, CA 92093-0225 United States
AB: The total heat output of the Earth constrains models of mantle and core dynamics. Recently this estimate has been questioned because the measured conductive heat flow on young oceanic lithosphere is about a factor of 2 less than the expected heat flow based on half-space cooling models. Taking the ocean heat flow values at face value reduces the global heat flow from 44 to 34 TW, which has major implications for geodynamics and Earth history. To help resolve this issue, we develop a new method of estimating oceanic heat flow from depth and age data. The overall elevation of the global ridge system, relative to the deep ocean basins, provides an independent estimate of the total heat content of the lithosphere. Heat flow is proportional to the measured subsidence rate times the heat capacity divided by the thermal expansion coefficient. Scalar subsidence rate is computed from gradients of depth and age grids. Unfortunately, the method cannot be applied over very young seafloor (< 3 Ma) where age gradient is discontinuous and the assumption of isostasy is invalid. Between 6 and 65 Ma the new estimates are in excellent agreement with half-space cooling models. Our independent estimate the total heat output of Cenozoic seafloor is 20.4 TW which leads to a global output of 44 TW in agreement with previous studies. The largest uncertainty in total oceanic heat output is due to uncertainties in heat capacity and thermal expansion coefficient. Experimental values of these parameters lead to global heat flow ranging between 42 and 51 TW.
DE: 8130 Heat generation and transport
SC: Tectonophysics [T]
MN: Fall Meeting 2005