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10 Cards in this Set
- Front
- Back
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Faults |
discontinuities along which there is visible offset by shear displacement |
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Slickensides |
the smooth or shinyfault surfaces themselves |
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slickenlines. |
Slickenlines aregenerally straight, fine-scale, delicate skin-deep lines that occupy the faultsurface itself and record the direction of slip |
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fault zone |
where the rock has been repeatedly faulted, orwhere the rock is especially weak, no single, discrete fracture or discontinuitymay be evident. What forms instead is a fault zone composed of countlesssubparallel and interconnecting closely spaced slip surfaces |
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shear zones |
. At deepcrustal levels, where rocks tend to deform plastically under conditions of elevatedtemperature and confining pressure, shear displacement is achieved by the developmentof shear zone |
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microfaults |
Some shear fractures can beconsidered to be microfaults, but they generally go unrecognized as suchbecause the tiny offset caused by shear cannot be easily resolved without aidof a microscope, or without the presence of fine-scale markers that record thedisplacement. |
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Fault Scarps |
are offsets or steps in the land surface that coincide withlocations of faults |
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fault-line scarps |
The passing of time permitsweathering and erosion to erase the original expressions of the fault offset.Fault scarps thus are gradually replaced by fault-line scarps |
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fault surface |
Where well exposed, faults are commonly expressed by the presence of a discretefracture break or discontinuity in the rocks along a fault surface (Figure 6.8). Therocks on either side of a fault surface do not “match up.” We use the term faultsurface instead of fault plane because faults are rarely perfectly planar. Some areplanar; some are made up of planar segments of varied orientations; some aresystematically curved; and some are highly irregular |
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Tip Line Loop |
Displacements were seen todecrease to zero from the central part of each elliptical fault surface outwardto the tip line loop, the imaginary line formed by connecting points |
