HR: 15:10h
AN: T43E-07    [Abstracts]
TI: Scaling of Natural Stylolites and Their use as Stress-Depth Gauges
AU: * Ebner, M
EM: ebnerm@uni-mainz.de
AF: Tectonophysics, Institut of Geoscience, Johannes Gutenberg University, Becherweg 21, Mainz, 55099, Germany
AU: Koehn, D
AF: Tectonophysics, Institut of Geoscience, Johannes Gutenberg University, Becherweg 21, Mainz, 55099, Germany
AU: Renard, F
AF: LGCA-CNRS-Observatoire, Université Joseph Fourier BP 53, 1381 rue de la piscine, Grenoble, F-38041, France
AU: Renard, F
AF: Physics of Geological Processes, University of Oslo, 1048 Blindern, Oslo, 0316, Norway
AU: Toussaint, R
AF: Institut de Physique du Globe de Strasbourg, UMR CNRS 7516, 5 rue Descartes, Strasbourg Cedex, F-67084, France
AB: Stylolites are rough dissolution pairs of surfaces that are generated by stress induced solution in sedimentary rocks. These irregular structures that can be found in various rock types are filled with fine-grained insoluble material. Stylolites have been shown to be self-affine fractal surfaces that have characteristic statistical properties (Schmittbuhl et al., 2004), which allow the characterisation of the roughness in a quantitative way, namely by the Hurst-exponent. With this approach it can be demonstrated that stylolites exhibit two scaling regimes with different roughness exponents, separated by a well-defined crossover-length (L) between small and large scales, respectively. According to the analytical solution of Schmittbuhl et al. these regions correspond to two thermodynamic regimes that are either dominated by surface or elastic energies, L being a function of the state of stress during stylolite formation. The aim of this contribution is to test the analytically predicted scaling of stylolites on a natural system of bedding-parallel stylolites. We show a correlation between L and the stress during stylolite formation and thus unravel the depth of stylolitization. For this, we sampled bedding-parallel stylolites from the Cirque de Navacelles (southern France), where a 300m succession of flat-lying Jurassic limestones crops out. The collected samples where cut normal to the mean stylolitic surface and the 1D stylolite profiles were digitized using a camera and image analysis techniques. For every sample, the roughness exponent and the corresponding crossover-length L of the 1D rough interface was calculated. To compare the results with the analytical solution, we calculated the elastic properties of typical samples from P- and S-wave velocities. Our results show that L decreases from 2 mm at the top of the profile to 0.7mm at the base. Plotting depth as a linear function of L allows the comparison of the slopes of the analytical solution and the natural samples. The present investigation reveals a validation for the analytical solution given by Schmittbuhl et al. We further conclude that our results utilise the construction of a robust and potentially very powerful new use of bedding- parallel stylolites as stress/depth gauges. Schmittbuhl, J., Renard, F., Gratier, J.-P., Toussaint, R., 2004. The roughness of stylolites: Implications of 3D high resolution topography measurements, Phys. Rev. Lett., 93, 238501.
DE: 8164 Stresses: crust and lithosphere
SC: Tectonophysics [T]
MN: 2007 Fall Meeting