GS 326 - STRUCTURAL GEOLOGY FAULT TERMINOLOGY (YOW!)

Hanging wall = block above fault plane Footwall = block below fault plane Slip vector = displacement of originally adjacent points Strike separation = apparent offset parallel to strike Dip separation = apparent offset parallel to dip heave = horizontal component of dip separation throw = vertical component of dip separation Dip-slip fault = movement parallel to dip of fault plane Strike-slip fault = movement parallel to strike of fault plane (also wrench fault, tear fault, transcurrent fault) left-lateral (sinistral) right-lateral (dextral) Oblique-slip fault = combined strike and dip slip Normal fault = hanging wall down relative to footwall Detachment fault = low-angle normal fault Reverse fault = hanging wall up relative to footwall Thrust fault = low-angle reverse fault Listric fault = shovel-shaped fault diping less steeply at depth Anastomosing = numerous, branching, irregular faults Translational fault = one in which no rotation occurs Rotational fault = one fault block rotates relative to the other Scissor fault = rotation with increasing displacement Slickensides = striations or mineral lineations on fault plane Fault trace (surface trace) = exposure of fault at surface Fault scarp = topographic exposure of fault plane Fault-line scarp = topographic exposure related to fault Tip line = where fault displacement goes to zero Branch line = where one fault intersects or branches from another Piercing points = linear feature offset along fault Fault breccia = randomly oriented angular clasts produced by faulting Fault gouge = smaller clasts, more matrix Crush breccia (fine crush, micro crush) = v. small fragments Protocataclasite, cataclasite, ultracataclasite = cohesive fault breccia Protomylonite, mylonite, ultramylonite = foliated, microbrecciated fault rock