[7] As the region continues to experience extensive pressures, there is an isostatic effect which moves ductile crust material underneath the fault complex.
[9] This fault system can shear the footwall, creating domal mountain ranges, which on a large scale can develop into formations known as metamorphic core complexes.
[5] If extension at the surface exceeds about 50 percent, decompression melting may permit magmas to form; these will deform the footwall, resulting in a complex associated with intrusive and extrusive igneous rocks.
Calculations examining sediment infill suggest that differences in core complexes can be controlled by erosion rates and hanging wall resistance of the fault.
[10] Block faulting of this nature is common in extensional settings and has been found to be an important part of physical geological models from sites around the globe, including Europe and China.
Tilted block development adapted from 2013 Whitney et al., "Continental and oceanic core complexes". The cartoon illustrates how the fault blocks tilt as time progresses in an extensional environment. Time A shows the pre-deformed rock unit. At time B, incipient normal faulting begins. At time C, faulting continues as extension continues. The associated extensional basins begin to fill with eroded material from the exposed blocks.
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A time lapse view of the fault block progression.
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Tilted fault blocks in
Tempe, Arizona
. Top frame shows the natural expression at the surface, while the bottom frame illustrates the possible pre-erosion three-dimensional formation. The tips of the block erode to fill in the surrounding basin.
An outcrop view of the extensional faulting that can produce tilting fault blocks.
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The faults have been highlighted in black, with the green line showing a marker horizon. The photograph is of an extensional fault array on cliffs west of Clarke Head, Minas Basin, North Shore,
Nova Scotia
.
