Occurrence of kaolinite and mixed-layer kaolinite/smectite in hydrothermal sediments of Grimsey Graben, Tjornes Fracture Zone (north of Iceland).

Dekov, V. M., Scholten, J., Botz, R., Garbe-Schönberg, C. D., Thiry, M., Stoffers, Peter and Schmidt, Mark (2005) Occurrence of kaolinite and mixed-layer kaolinite/smectite in hydrothermal sediments of Grimsey Graben, Tjornes Fracture Zone (north of Iceland). Marine Geology, 215 (3-4). pp. 159-170. DOI 10.1016/j.margeo.2004.12.004.

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Abstract

The sediments at a site situated among high-temperature vents in the Grimsey Graben (Tjornes Fracture Zone, north of Iceland) exhibit features of strong hydrothermal alteration: (1) almost total dissolution of the volcaniclastic material composing the background sediment; (2) sulfate and sulfide precipitation; (3) kaolinitisation. Smectite, precipitated in the shallowest sediment, is gradually replaced downward by mixed-layer kaolinite/smectite and pure, well-crystallised kaolinite. The kaolinite/smectite is interstratified with up to 10% swelling smectitic layers. According to the oxygen isotope composition kaolinite/smectite mixed-layer mineral most likely formed at temperatures near 160 degrees C. The vertical sequence kaolinite -> kaolinite/smectite -> smectite as well as the distinct zonation across the kaolinitic veins (almost pure kaolinite in the central zone and kaolinite/smectite along the rim) suggest hydrothermal transformation of initially formed smectite -> kaolinite/smectite -> kaolinite. Most probably this conversion occurred in an evolving (from alkaline to slightly acidic) hydrothermal environment. (c) 2004 Elsevier B.V. All rights reserved.

Document Type: Article
Keywords: kaolinite mixed-layer kaolinite/smectite Grimsey vent field hydrothermal alteration de-fuca ridge clay-minerals middle valley sea-floor kolbeinsey ridge spreading center paris basin smectite deposits montmorillonite
Research affiliation: Kiel University
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.margeo.2004.12.004
ISSN: 0025-3227
Expeditions/Models/Experiments:
Date Deposited: 18 Jan 2012 05:09
Last Modified: 08 Aug 2017 12:48
URI: http://oceanrep.geomar.de/id/eprint/16046

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