![]() The term is used for thrust faults of regional extent. Overthrust fault This is an older term that you may find in older papers on faults, but is no longer used much today. In the field, faults with a slip direction between ?10° and ?80° are generally called oblique-slip. Oblique-slip faultThe slip direction on an oblique-slip fault has a rake that is not parallel to the strike or dip of the fault. Normal fault A normal fault is a dip-slip fault on which the hanging wall has slipped down relative to the footwall. Extensional fault An extensional fault is one whose displacement results in extension of the layers that the fault cuts, regardless of the orientation of the fault with respect to horizontal. Dip-slip fault The slip direction on a dip-slip fault is approximately parallel to the dip of the fault (i.e., has a rake between ?80° and 90°). Overthrust are listric, and on some detachments, regional normal-sense displacement occurs. An older term “overthrust” is a regional detachment fault on which there has been a thrust sense of movement. Detachment faultThis term is used for faults that initiate as a horizontal or subhorizontal surface along which the hanging-wall sheet of rock moved relative to the footwall. Contractional fault A contractional fault is one whose displacement results in shortening of the layers that the fault cuts, regardless of the orientation of the fault with respect to horizontal.ĭécollement The French word for detachment. AutochthonThe footwall below a detachment is the autochthon it is composed of autochthonous rock, or rock that is still in its place of origin. Allochthon The thrust sheet above a detachment is the allochthon (meaning that it is composed of allochthonous rock i.e., rock that has moved substantially from its place of origin). A fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movement.
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