[S-CG49] Rheology, fracture and friction in Earth and planetary sciences

[SCG49-P04] Study on application scope of permeability tensor theory to anisotropic mineral veins in natural outcrops

*Hinako Hosono¹, Takato Takemura¹ (1.Devision of Earth Information Mathematical Sciences, Graduate School of Integrated Basic Sciences, Nihon University )

Keywords:Paleo-permeability, Three-dimensional crack density

Permeability behavior of cracked rocks is very important to understand the underground environment. Especially, the fluid behavior in the damage zone of the seismic faults has been focused on when discussing the mechanism of an earthquake (e. g. Sibson, 1992). However, it is difficult to actually measure the permeability of such a damage zone since the seismic zone was located at a large depth, and it can only be inferred from the outcrop of the damage zone of past seismic faults. Furthermore, since the cracks that were the past water pathways are filled with minerals before the rock body was uplifted, it is impossible to actually measure the past permeability from the samples. Therefore, the crack tensor theory and permeability tensor theory proposed by Oda (1984) were applied to the mineral veins. These theories are used as effective tools to estimate permeability from field investigation information (e. g. Iannou et al., 2007, Healy et al., 2017). However, some issues remain, such as in estimating the three-dimensional geometries from the cross-section. In this study, we focused on the method of calculating the three-dimensional crack density using scanning lines on a two-dimensional plane in the process of applying the crack tensor (Oda, 1984, Takemura & Oda, 2004). This study investigates how precisely geometry estimation from two-dimensional cross-sections can be evaluated when randomly anisotropic disk-shaped cracks are generated in an arbitrarily three-dimensional space.

References
Healy, D., Rizzo, R. E., Cornwell, D. G., Farrell, N. J., Watkins, H., Timms, N. E., Gomez-Rivas, E. & Smith, M. (2017). J. Struct. Geol., 95, pp. 1-16.
Ioannou, S. E., & Spooner, E. T. C. (2007). Econ Geol., 102(4), pp. 667-690.
Oda, M. (1984). Mech. Mater., 3(2), pp. 119-129.
Sibson, R. H. (1992). Tectonophysics, 211(1–4), pp. 283–293.
Takemura, T., & Oda, M. (2004). Tectonophysics, 387(1-4), pp. 131-150.