HR: 0830h
AN: V21D-0550    [PDF]
TI: Constraining Hydrothermal Fluxes: Insights From the Northern Oman Ophiolite
AU: * Davis, A C
EM: amy@esc.cam.ac.uk
AF: Department of Earth Sciences, University of Cambridge, Cambridge, CB2-3EQ United Kingdom
AU: Bickle, M J
EM: mb72@esc.cam.ac.uk
AF: Department of Earth Sciences, University of Cambridge, Cambridge, CB2-3EQ United Kingdom
AU: Chapman, H J
EM: hjc1000@esc.cam.ac.uk
AF: Department of Earth Sciences, University of Cambridge, Cambridge, CB2-3EQ United Kingdom
AU: Teagle, D A
EM: dat@soc.soton.ac.uk
AF: Southampton Oceanography Centre, University of Southampton, Southampton, SO14-3ZH United Kingdom
AB: Hydrothermal circulation is an intrinsic process at all oceanic spreading centres and makes an important contribution to global geochemical cycles. However, large uncertainties remain in the magnitude of hydrothermal fluxes and the hydrothermal contribution to global geochemical budgets. A multi-phase hydrothermal system in the northern Oman ophiolite is investigated as an analogue for understanding modern oceanic process and the magnitude of hydrothermal fluxes in arc-related environments. Field mapping of the Wadi Rajmi area combined with trace element discrimination methods are used to identify three hydrothermal regimes which correlate with the complex magmatic-tectonic evolution of the area. The first hydrothermal regime is associated with formation and cooling of the crustal (V1) sequence within an oceanic spreading environment. The second and third regimes are associated with later (V2) localised magmatic intrusions in an off-axis environment. Strontium isotope geochemistry is used to investigate the character of each regime and predict a time-integrated high-temperature fluid flux of $\sim$4.5$\pm$1.1 x 10$^{7}$ kgm$^{-2}$ for the initial spreading related hydrothermal event and lower estimates for the later regimes. The flux calculated is comparable to a similar prediction made for the Troodos ophiolite (Bickle \& Teagle, 1992), but is significantly higher than that calculated for mid-ocean ridge systems (Teagle et al, 2003). This supports previous suggestion that oceanic spreading systems in supra-subduction settings maintain greater hydrothermal fluxes than normal oceanic environments, and this has important implications for the hydrothermal contribution to global geochemical budgets
DE: 0330 Geochemical cycles
DE: 1040 Isotopic composition/chemistry
DE: 3015 Heat flow (benthic) and hydrothermal processes
DE: 3035 Midocean ridge processes
DE: 8135 Hydrothermal systems (8424)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting