Search results
Results from the WOW.Com Content Network
A graben is a section of crust that has lowered relative to the blocks on either side, which is a result of its bounding faults dipping towards each other. [2] The plural of graben can be either graben or grabens. Graben form low-lying features such as basins and rift valleys. [1] [2] They can be very long relative to their width.
Graben often occur side by side with horsts. Horst and graben structures indicate tensional forces and crustal stretching. Graben are produced from parallel normal faults, where the displacement of the hanging wall is downward, while that of the footwall is upward. The faults typically dip toward the center of the graben from both sides.
In physical geography and geology, a horst is a raised fault block bounded by normal faults. [1] Horsts are typically found together with grabens. While a horst is lifted or remains stationary, the grabens on either side subside. [2] This is often caused by extensional forces pulling apart the crust.
Lake-filled half-graben showing sedimentation dominantly from the 'hinge' margin. Four zones of sedimentation can be defined in a half-graben. The first is "escarpment margin" sedimentation, found along the major border faults bounding the half graben, where the deepest part of the basin meets the highest rift-shoulder mountains. [6]
A few kilometers south of Cairo there are en echelon minor faults between two major faults that produce a relay ramp style transfer zone. In the northern part of the Suez rift system the Gharandal transfer zone accommodates deformation in a broad anticlinal structure between two listric faults in a collateral horst and graben.
In areas of high crustal stretching, individual extensional faults may become rotated to too low a dip to remain active and a new set of faults may be generated. [3] Large displacements may juxtapose syntectonic sediments against metamorphic rocks of the mid to lower crust and such structures are called detachment faults.
The Ottawa-Bonnechere Graben measures about 700 km (435 mi), running from the Montreal area on the east to near Sudbury and Lake Nipissing on the west. [2] On the east, it joins the Saint Lawrence rift system, a half-graben which extends more than 1000 km along the Saint Lawrence River valley and links the Ottawa and Saguenay Graben. [3] [4]
The Limagne graben formed from the Eocene to the Oligocene as the part of the European Cenozoic Rift System (ECRS) which extends offshore as the Gulf of Lions and Valencian trough. The ECRS also includes the Upper Rhine graben, Rhône graben, Saône graben, Lower Rhine Embayment and Leine graben as well as the Eger graben in the Bohemian Massif.