Botz, R. W. and Stoffers, P. (1992) Isotopic composition of hydrothermal precipitates from the Mariana Trough. Marine Geology, 108 (2). pp. 239-243. DOI 10.1016/0025-3227(92)90175-h.

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Abstract

Hydrothermal silica chimneys from the axial region of the Mariana Trough were investigated for their oxygen isotopic composition. The opal-CT samples revealed [delta]18O values between 28.5 and 31.2[per mille sign]. This range of [delta] values indicates precipitation temperatures between 31.5° and 57.2° C (minimum and maximum temperatures using different equations describing the silica-water equilibrium and assuming a [delta]18O value of 0[per mille sign] for the hydrothermal fluid). Two coexisting (with opal-CT) nontronite samples have an isotopic composition of 26.3 and 26.6[per mille sign]. A formation temperature near 20°C results for this nontronite. It is inferred that both mineralogical phases (opal-CT and nontronite) are not cogenetic as they did not precipitate at the same temperature from the same solution.

Document Type:	Article
Research affiliation:	Kiel University
Refereed:	No
Date Deposited:	02 Feb 2012 09:28
Last Modified:	23 Sep 2019 19:24
URI:	https://oceanrep.geomar.de/id/eprint/16392

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