Two‐ and three‐dimensional thermal modeling of a low‐angle detachment: Exhumation history of the Simplon Fault Zone, central Alps

摘要: [1] Two alternative models have been proposed to explain footwall exhumation along major low-angle detachments: (1) crustal-scale a detachment fault that maintained low dip angle or (2) high-angle passively rotated by isostatic rebound (“rolling hinge model”). These were tested against well-documented example of in the European central Alps, Simplon Fault Zone (SFZ). An extensive thermochronological data set provides basis for 2- and 3-D thermokinematic (Pecube), coupled with stochastic inversion algorithm (the Neighbourhood Algorithm). Model results establish pattern is better reproduced 30° dip, rather than rolling model. Although range histories involving either steady state variable rates possible, preferred model highest probability rate, zone initiated at 18.5 ± 2.5 Ma active until present day. Footwall was relatively fast 14.5 1.5 (∼1.4 mm yr−1). This enhanced SFZ similar timing kinematics orogen-parallel extension reported throughout Alpine orogen. After Ma, continued reduced rate (∼0.7 yr−1) 4 Ma. The subsequent increase (to ∼1 reflects regional erosion across both hanging wall after circa (from 0.35 0.15 yr−1 0.70 yr−1), probably response climate changes during Pliocene.