Extensional fault-propagation folds: mechanical models and observations from the Modoc Plateau, northeastern California

摘要: Extensional fault-propagation folds are produced by warping of material ahead a growing normal fault. We use field observations surface-breaking faults in the Modoc Plateau, California, conjunction with three-dimensional linear elastic boundary element computer models, to address mechanical controls on extensional fault propagation folds. Detailed topographic and structural maps near-tip regions several kilometer-long reveal: throw decreases rapidly toward tip, suggesting elliptical slip distributions; fault-parallel monoclinal present beyond axes offset into hanging wall; open fissures common tip region. Parametric tests model show that amplitude form at terminations influenced distribution, dip, properties rock, presence or absence blind portion Models reproduce observed first order suggest faults, both isolated relay zones, probably for some lateral extent surface break.