Sealing, healing and fluid flow in clay rocks : Insights on episodic flow events in fault zones

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Nenonen , V , Dick , P , Sammaljärvi , J , Johansson , B , Voutilainen , M & Siitari-Kauppi , M 2019 , Sealing, healing and fluid flow in clay rocks : Insights on episodic flow events in fault zones . in 5th International Conference on Fault and Top Seals 2019 : Proceedings of a meeting held 8-9 September 2019, Palermo, Italy . EAGE , pp. 236-240 , 5th International Conference on Fault and Top Seals 2019 , Palermo , Italy , 08/09/2019 . https://doi.org/10.3997/2214-4609.201902324

Title: Sealing, healing and fluid flow in clay rocks : Insights on episodic flow events in fault zones
Author: Nenonen, Ville; Dick, P.; Sammaljärvi, Juuso; Johansson, B.; Voutilainen, Mikko; Siitari-Kauppi, Marja
Contributor: University of Helsinki, Department
University of Helsinki, Department of Chemistry
University of Helsinki, Faculty of Science
University of Helsinki, Geological disposal of spent nuclear fuel
Publisher: EAGE
Date: 2019
Language: eng
Number of pages: 5
Belongs to series: 5th International Conference on Fault and Top Seals 2019 Proceedings of a meeting held 8-9 September 2019, Palermo, Italy
ISBN: 978-1-5108-9236-1
URI: http://hdl.handle.net/10138/314442
Abstract: The porosity distribution and mineralogical changes in a clay-rich fault core from the Tournemire underground research laboratory are analyzed to determine the mechano-chemical processes in a small-scale vertical strike-slip fault. The results display significant spatial variations in porosity and mineralogy along different gouge zones due to a polyphased tectonic history combined with complex paleo-fluid migrations. Porosity values increase from the center of the gouges to their borders indicating diffusive sealing/healing effects and past hydrothermal activities. The healing and thus the strengthening of the fault is marked by an increase of calcium content, which is concurrent with lower porosities around the gouge zone. Chemical mapping in the gouges reveal clay alteration, iron zonality and the presence of zinc sulphide as well as barium sulphate inside the gouge, further suggesting past hydrothermal activity. Finally, even though the observed porosity variations only occur in subcentimeter-thick gouge bands, the higher porosity sections are pathways for fluid flow during fault activity. © 5th International Conference on Fault and Top Seals 2019. All Rights Reserved.
Subject: Barium compounds
Chemical analysis
Clay alteration
Minerals
Porosity
Research laboratories
Strike-slip faults
Structural geology
Sulfur compounds
Zinc sulfide
Chemical mapping
Hydrothermal activity
Mechanochemical process
Mineralogical changes
Porosity distributions
Porosity variations
Spatial variations
Underground research laboratories
Flow of fluids
1171 Geosciences
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