Kern, H., Popp, T. and Takeshita, T. (1992) Characterization of the thermal and thermomechanical behaviour of polyphase salt rocks by means of electrical conductivity and gas permeability measurements. Tectonophysics, 213 (3-4). pp. 285-302. DOI 10.1016/0040-1951(92)90459-j.

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Abstract

Measurements of electrical conductivity and gas permeability in carnallite-halite-kieserite rocks were carried out under hydrostatic (2.5-24.0 MPa) and non-hydrostatic pressure conditions (strain rate: 10-7-10-8s-1) at temperatures up to 125°C in order to obtain information on the thermal and thermomechanical stability of hydrated carnallite (KMgCl3) · 6H2O and the corresponding state of rock microstructure. At hydrostatic pressure an anomalous increase in conductivity with increasing temperature was observed at 100°C which is attributed to a release of chemically bound water. Isothermal deformation of carnallitic rocks (non-hydrostatic pressure) is accommodated by the interaction of different deformation mechanisms (cataclastic flow, intracrystalline slip, mechanical twinning and dynamic recrystallization). Increasing temperature or increasing humidity on grain boundaries shifts the deformation behaviour from "brittle" to "ductile", due to the onset of dynamic recrystallization and leads to a significant weakening of the rock. The brittle/ductile transition is indicated by characteristic signatures of the electrical conductivity and gas permeability/strain relations. The combination of both parameters allows one to separate the effects on conductivity caused by deformation-related changes in porosity from those caused by dehydration reactions.

Document Type:	Article
Research affiliation:	Kiel University
Refereed:	No
Date Deposited:	02 Feb 2012 09:27
Last Modified:	23 Sep 2019 23:28
URI:	https://oceanrep.geomar.de/id/eprint/15526

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