Hydrothermal Activity at Slow-Spreading Mid-Ocean Ridges: Evidence from Chlorine in Basalt.

van der Zwan, Froukje M. (2014) Hydrothermal Activity at Slow-Spreading Mid-Ocean Ridges: Evidence from Chlorine in Basalt. (PhD/ Doctoral thesis), Christian-Albrechts-Universität, Kiel, 120 pp.

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Hydrothermal activity can be traced by the chlorine (Cl) concentrations of erupted mid-ocean ridge basalts, if their magmas assimilated hydrothermally altered, Cl-rich crust. In contrast to fast-spreading ridges, this process is not observed so far at slow-spreading ridges, due to their intrinsically lower basaltic Cl contents (<200 ppm). This study involves the development of a new, high precise (<2 ppm SD) technique to measure Cl by electron microprobe, which is applied to basaltic glasses and mineral melt-inclusions from the southern Mid-Atlantic Ridge, the Red Sea Rift and the Gakkel Ridge (all <3.5 cm/yr). Addition of hydrothermal Cl is determined by comparing Cl with major and trace element concentrations. Chemical thermobarometry is used to obtain depth information on hydrothermal circulation. Cl data is compared to geological settings (e.g. hydrothermal sites, volcanoes, faults) to examine their relationships and to assess basaltic Cl as prospection tool for hydrothermal vents.

Document Type: Thesis (PhD/ Doctoral thesis)
Thesis Advisor: Devey, Colin W. and Hansteen, Thor H.
Keywords: chlorine, mid-ocean ridge basalt, hydrothermal activity, slow-spreading ridges, Red Sea, Gakkel Ridge, southern Mid-Atlantic Ridge
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS
Projects: Jeddah Transect
Date Deposited: 22 Jul 2014 07:21
Last Modified: 30 Oct 2014 09:35
URI: http://oceanrep.geomar.de/id/eprint/25312

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