Crustal Stretching Seismic Interpretati
Crustal stretching Seismic Interpretation
By: Donovan Durham
Introduction
The Caledonian orogeny happened during the late Silurian to early Devonian periods. This was due to the westward subduction of Baltican plate beneath the Laurentian margin. The continent to continent orogeny resulted in a over thickened crust. During the Palezoic orogeny several different processes were at work simultaneously, which included erosion, plate divergence, gravity driven collapse of the orogenic wedge, and viscous flow of the lower crust. The double set of extensional shear zones consists of an upper to middle crust collision and lower crust and upper mantle collision, which dipped in the opposite direction of the Mohorovicic-offsetting shear zone. These events caused crustal stretching of the lower crust and upper mantle. The upper to middle crust had extensional reactivation of the thrust as well as the formation of new extensional faults and shear zones. When the lower crust came into contact with the upper mantle a more enigmatic collision occurred. The tectonic collision resulted in the formation of a Foreland and Hinterland basins.
Context
The data was interpreted suggesting the extensional shear zone had a true displacement of approximately 50 km The correlation of the two lines suggest that the shear zone that offsets the (Moho) strikes parallel to the Hardangerfjord shear zone (HSV or upper to middle crust), but with a opposite dip direction. The true dip is between 15 and 20 degrees to the southeast. Evidence suggests that the (Moho) was clearly down set towards the south. The 50km offset is much greater than other offsets could agree with. The other offsets would only be expected to be a few km. The fact that the HSV affects the Caledonian deposition enviroments, shows that its present offset accumulated during post thrusting. It is also possible that it involves Proterozoic offset, including Neo-Proterozoic crustal stretching. The location is parallel
By: Donovan Durham
Introduction
The Caledonian orogeny happened during the late Silurian to early Devonian periods. This was due to the westward subduction of Baltican plate beneath the Laurentian margin. The continent to continent orogeny resulted in a over thickened crust. During the Palezoic orogeny several different processes were at work simultaneously, which included erosion, plate divergence, gravity driven collapse of the orogenic wedge, and viscous flow of the lower crust. The double set of extensional shear zones consists of an upper to middle crust collision and lower crust and upper mantle collision, which dipped in the opposite direction of the Mohorovicic-offsetting shear zone. These events caused crustal stretching of the lower crust and upper mantle. The upper to middle crust had extensional reactivation of the thrust as well as the formation of new extensional faults and shear zones. When the lower crust came into contact with the upper mantle a more enigmatic collision occurred. The tectonic collision resulted in the formation of a Foreland and Hinterland basins.
Context
The data was interpreted suggesting the extensional shear zone had a true displacement of approximately 50 km The correlation of the two lines suggest that the shear zone that offsets the (Moho) strikes parallel to the Hardangerfjord shear zone (HSV or upper to middle crust), but with a opposite dip direction. The true dip is between 15 and 20 degrees to the southeast. Evidence suggests that the (Moho) was clearly down set towards the south. The 50km offset is much greater than other offsets could agree with. The other offsets would only be expected to be a few km. The fact that the HSV affects the Caledonian deposition enviroments, shows that its present offset accumulated during post thrusting. It is also possible that it involves Proterozoic offset, including Neo-Proterozoic crustal stretching. The location is parallel