Locating hydrothermal vents by detecting buoyant, advected plumes

Citation
Sr. Veirs et al., Locating hydrothermal vents by detecting buoyant, advected plumes, J GEO R-SOL, 104(B12), 1999, pp. 29239-29247
Citations number
39
Categorie Soggetti
Earth Sciences
Journal title
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
ISSN journal
21699313 → ACNP
Volume
104
Issue
B12
Year of publication
1999
Pages
29239 - 29247
Database
ISI
SICI code
0148-0227(199912)104:B12<29239:LHVBDB>2.0.ZU;2-8
Abstract
An improved method of detecting buoyant hydrothermal plumes and locating th eir source vents is introduced. Plumes are detected by computing fluid stab ility from conductivity, temperature, and depth measurements acquired durin g navigated, towed, vertically oscillating casts over the Endeavour Segment of the Juan de Fuca Ridge. For each instability detected, the maximum rang e to its hydrothermal source is estimated by multiplying a theoretical plum e equilibration time by a measured current velocity. Using an estimate of c urrent direction, the method reliably locates plume soul-ces where they are known to exist: in all of the focused vent fields mapped by submersible an d in several isolated, diffuse flow sites. The method generates a distribut ion of hydrothermal sources that is more consistent with variations in surf ace permeability than with circulation cells spaced evenly along a uniforml y permeable axis. Axial instabilities are nearly continuous along the heavi ly fissured and fractured western wall of the axial valley. Beyond the axia l valley, instabilities evidence that hydrothermal upflow penetrates the ou ter slopes of the ridge crest, probably along a boundary between sheet and pillow flows.