Large-magnitude continental extension: An example from the central Mojave metamorphic core complex

摘要: The central Mojave metamorphic core complex is defined by a belt of Miocene brittle-ductile extension and coeval magmatism. fault zone defines basin-and-dome geometry that results from the interference two orthogonal fold sets we infer to have formed mechanically independent processes. One set contains axes lie parallel direction shear has maximum characteristic wavelength about 10 km. axial surfaces these folds can be traced footwall mylonites, through brittle detachment, into hanging-wall strata. However, mylonitic layering smaller interlimb angles than those suggesting began form during ductile shearing continued amplify in regime, possibly after movement across ceased. Mesoscopic fabrics related transport-parallel indicate record true crustal shortening perpendicular direction. We interpret response elevated horizontal compressive stress suggest this regime may natural consequence large-magnitude extension. other 50 include northwest-striking joints, kink bands, en echelon tension-gash arrays. These mylonitization both layer-parallel northeast-side-up subvertical shear. postmylonitic are kinematically compatible with rolling-hinge-style isostatic rebound following tectonic denudation. relative timing extension-related magma intrusion deformation varies complex. On scale small mountain ranges make up complex, no correlation was observed between either thickness or intensity proximity volume igneous rocks. This suggests models invoke single upper-crustal genetic relationship, such as magmatism triggering vice versa, do not apply Systematic variation dike emplacement that, at time emplacement, rocks Mitchel Range were below transition while Hinkley Hills above it. separated ∼2 km dip zone, which vertical probably 100 950 m.