Relict subduction zones in Canada

摘要: [1] Relict subduction zones that are interpreted on 10 Lithoprobe deep seismic reflection profiles in Canada provide key observational evidence lithosphere plate interactions have operated with essentially the same resultant geometry for at least 2.7 Gyr. Subduction zone reflections generally found beneath known collisional belts, and their orientations often consistent locations of exposed arcs, sutures, complexes. They project from lower crust into upper mantle geometric relationships between crust, Moho, mantle. The interpretation as being syntectonic establishes a minimum age overlying wedge precludes inferred formation Moho by postorogenic delamination these areas. orientation may be synthetic or antithetic to indicating juxtaposition subcretion delamination, respectively. above exhibit sparse reflectivity. commonly dip toward craton, preferred during last stages convergence within an orogen, else higher likelihood preservation older domains. Interpreted ages Canadian examples range Recent Neoarchean (∼2.7 Ga), providing tectonics similar processes been active since Neoarchean. geometries relict snapshot accretion boundaries establish framework Neoarchean-Recent accretionary architecture North American lithosphere.