Magnitude and variance of near-bottom horizontal heat flux at the Main Endeavour hydrothermal vent field

• Published in: Geochemistry, geophysics, geosystems : G3 geophysics, geosystems : G3, 2006-02, Vol.7 (2), p.np-n/a
• Main Authors: Veirs, Scott R., McDuff, Russell E., Stahr, Frederick R.
• Format: Article
• Language: English
• Subjects: currents; heat; heat flux; hydrography; hydrothermal; vents
• ISSN: 1525-2027; 1525-2027
• DOI: 10.1029/2005GC000952

We characterize hydrothermal plumes and hydrography within the axial valley of the Endeavour segment (Juan de Fuca ridge, northeast Pacific) using data from an autonomous underwater vehicle, a lowered CTD, and two current meter moorings. Our survey of the Main Endeavour hydrothermal vent field (MEF) shows hydrographic variability on scales as short as ∼20 m and ∼10 min. Within the ∼100 m deep axial valley, the mean flow is 1–5 cm/s to the north, and tidal oscillations have ∼5 cm/s amplitude. Combining the mean flow with an estimate of the difference in average temperature observed north and south of MEF, we find that the net along‐axis horizontal heat flux has a mean magnitude of ∼8–42 MW. An advection/diffusion model forced by local current records explains the observed temporal hydrographic variability and shows that mean horizontal flux variance is correspondingly high (standard deviation ∼63 MW). A steady state MEF heat budget, constrained by the observed horizontal flux and measurements of vertical fluxes from other studies, has two implications: the MEF heat flux is partitioned about equally between diffuse and focused vents, and about 85% of the flux from diffuse plumes is entrained by focused plumes.