Fig. 4
From: Kink strengthening and rank-1 connection of crustal rocks
Schematic figures of the kink band and the triangular diagram for analyzed kink geometry. (a) A schematic figure of a kink band and the angles that characterize its geometry. \({\sigma }_{1}\) denotes the maximum principal stress direction. (b) Triangular plot of kink angles as proposed in ref.38. The three kink band angles Φ, Φk, and Ψ shown in (a) have the following relationship by definition: Φ + Φk + Ψ = 180°. At each vertex of the triangle, angles Φ, Φk, and Ψ are 180°, respectively, and gradually decrease to 0° along the normal direction dropped from the vertex to the opposite side. At the three sides of the triangle (Φk(180) − Ψ(180), Φ(180) − Ψ(180), Φ(180) − Φk(180)), angles Φ, Φk, and Ψ are 0°, respectively. The red lines indicate changes in angle associated with kink growth, while the red circles indicate example angles at the point of kink nucleation. The Roman numerals I - IV correspond to each kink growth model (see Supplementary Text 2 for details about kink growth models). (c) The results of sample A (Pc: 10 MPa, T: 300 °C, DC: [010]). (d) The results of sample E (Pc: 185 MPa, T: 300 °C, DC: [010]). The results of both samples A and E are concentrated around Φ = Φk. In sample E, where the confining pressure is higher, the value of Ψ is much larger than that of sample A. Hence, an apparent dependence on confining pressure is observed.
