Fig. 8: Results of Triaxial tests.
Above: Photographs of samples after experimental deformation at Pc = 60 MPa and T = 60 °C—the cylinder’s dimensions are 54 × 114 mm. All samples experienced a through-going shear fracture that formed an acute angle with the vertical maximum principle stress σ1. a and b Show different deformation in the same cylinder of Osa Mélange basalt as failure is accommodated by a single tortuous fracture where no relict cores are present (A) whereas fractures exploit and reactivate fractures around and between the cores where present (b). c The volcanoclastic matrix failed by a single fracture with visible displacement and a loss of cohesion. d The Cocos Ridge basalt failed by a single curved fracture with visibly negligible displacement and mild tortuosity. Below: e Summary of mechanical results, showing peak stress and static Young’s modulus values for altered basalt, volcanoclastic matrix, and Cocos Ridge basalt under 60 MPa/60 °C, 120 MPa/60 °C, and 120 MPa/120 °C.
