Crustal Geometry and Extensional Models for the Grand Banks, Eastern Canada: Constraints from Deep Seismic Reflection Data

摘要: Abstract Deep seismic reflection data, allowing crustal and upper mantle reflectors to be delineated, were collected across the sedimentary basins in Grand Banks region of eastern Canada. Interpretation results indicates that narrow, half-grabens on formed by extension, which was accommodated major faults. These bound each extend deep into crust, possibly flattening along Moho or just above it. reflections show little topography when displayed against two-way travel time, although converted depth they will rise slightly beneath lower velocity sediments basins. A reflective layer is also observed below platform regions Banks. This becomes less pronounced basins, explanation for this unknown. The geometry faults are used constrain extensional models basin evolution. Extension appears describe stretching, whereas crust subcrustal lithosphere assumed undergo penetrative extension. stretching model based these assumptions satisfies most observations such as shape free air gravity anomaly. However, isostatic compensation load water cannot modelled Airy local isostasy; an elastic plate with finite flexural rigidity required support loads during both syn-rift post-rift history. Both data modelling idea extension lithosphere, causing localized deformation underlain a broad zone ductile flow.