Mechanisms of thrust propagation: some examples and implications for the analysis of overthrust terranes

摘要: Abstract Evidence is presented for the existence of three fundamental mechanisms by which thrust sheets move. The are: (1) failure a stiff layer, to form ramp-flat geometry (‘imbricated’ sheets); (2) detachment layer folding (‘decollement” (3) differential layer-parallel shortening (‘LPS’ sheets). are independent but may operate interactively families ‘hybrid” sheets. Since LPS have not been previously described or documented, data from New York plateau, deformed almost exclusively LPS, demonstrate physical characteristics this mechanism. Information plateau indicates that finite-strain behavior closely reflects geometric boundary conditions and temperature depth burial. Finite-strain used construct set iso-strain maps in both undeformed states. turn determine displacement field sheet. allows visualization effects Lagrangian Eulerian transformations on an initially orthogonal grid. Utilizing sections number overthrust belts, it shown occur universally although various proportions. regionally developed throughout central northern Appalachians. presence probably accounts structural cross-sections bed-length balance these blind terranes. Finally series examples drawn as well literature illustrate hybrid sheet indicate how knowledge their can be utilized developing strategies construction balancing cross-sections.