Alkali elements as geothermometers for ridge flanks and subduction zones

W. Wei, M. Kastner, R. Rosenbauer, L. H. Chan, Y. Weinstein

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review


Hydrothermal experiments were conducted on basaltic ash and smectite, with a water/rock mass ratio of ~5-8, at 600 bar pressure. The reaction temperature was gradually changed from 35 to 350°C at 20-50°C increments, and at each temperature steady-state was reached. The results indicate that each alkali metal has a distinct temperature-dependant partition profile between fluid and the solid phase. The data indicate significant fractionations among alkali metals from 35-350°C and a strong influence by the starting solids on the mobility of the alkali metals. The reactivity of the solid for Li isotopes increases dramatically with temperature. Cesium exhibits significant affinity for the fluid at temperatures as low as 150°C, suggesting that ridge flanks may be an important source of Cs to the ocean. The results also suggest that alkali element ratios together with Li isotope ratios may be used as approximate geothermometers for deep-sourced fluid at subduction zones.

Original languageEnglish
Title of host publicationWater-Rock Interaction
PublisherCRC Press
Number of pages3
ISBN (Electronic)9781439862995
ISBN (Print)9780415604260
StatePublished - 1 Jan 2010

Bibliographical note

Publisher Copyright:
© 2010 Taylor & Francis Group, London.


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