Origin of Meteoric Fluids in Extensional Detachments

Figure 3

Schematic differential stress and pressure profiles. (a) Absolute differential stress to achieve an extension rate that is depth-independent, assuming a maximum differential stress of 100 MPa at a brittle-ductile transition of about 6 km. (b) In a crust at rest, the fluid pressure profile would show a transition from hydrostatic at a shallow depth to lithostatic further down. Grey area shows the fluid overpressure that results from bringing the crust under extension. (c) Exhumation shifts the fluid pressure profile upward if fluid cannot escape from the pores. Grey area shows the resulting fluid overpressure. Both extension and exhumation may thus result in fluid pressures that exceed the lithostatic and thereby cause fluid release.