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Title: Modelling fluid flow in seafloor hydrothermal systems
Author: Dickson, P. C.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 1997
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A series of theoretical models are developed in order to constrain the fundamental underlying controls on low-temperature hydrothermal circulation in seafloor venting systems. In terms of discharge, results of these models predict that (i) some diffuse flow will always exit permeable sulphide mounds or oceanic crust in the vicinity of black smoker vents, (ii) diffuse flow may also occur in the absence of seafloor black smoker venting and (iii) anticorrelated variations in diffuse flow temperature and vertical velocity previously recorded at a sulphide mound on the Juan de Fuca Ridge may have been caused by variations in either the isotropic or vertical permeability of the mound. In terms of recharge, model results predict that the volume flux of seawater entrained into seafloor hydrothermal systems and subsequently discharged as diffuse flow appears to primarily depend on the permeability of the system and on the circulation depth of the entrained seawater. Furthermore, the principal location of such entrainment along the surface of a sulphide mound is determined, to a large extent, by the permeability structure and aspect ratio of the mound. Hydrothermal flow models of subsurface mixing between black smoker fluid and seawater predict that diffuse flow evolves towards a white smoker type fluid as mineral precipitation reduces the permeability of the system. Conversely, low-temperature hydrothermal fluids exiting such systems are predicted to evolve towards a diffuse flow type fluid following permeability-enhancing events. Furthermore, results from sulphide mound models suggest that anhydrite precipitation resulting from low-temperature hydrothermal circulation may act as a self-promoting process.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available