Changes

==Magnetics vs. other techniques==

==Magnetics vs. other techniques==

We might question the strong emphasis on magnetics for mapping the [[basement]] fault block pattern. However, is there any other way to reliably map this pattern beneath the sedimentary section? Methods that depend on surface information—Landsat, SLAR, conventional photo geology, and surface geology—are of limited value. That leaves only gravity and seismic techniques.

We might question the strong emphasis on magnetics for mapping the [[basement]] fault block pattern. However, is there any other way to reliably map this pattern beneath the sedimentary section? Methods that depend on surface information—Landsat, SLAR, conventional photo geology, and surface geology—are of limited value. That leaves only [[gravity]] and seismic techniques.

However, gravity techniques generally do not separate adjacent basement blocks because of the lack of density contrast between adjacent blocks and because of interference from density differences within the sedimentary section. On seismic data, the basement reflector is often difficult to recognize beneath complex structure and because of a lack of velocity contrast with the dense dolomites that overlie the basement in many areas. Furthermore, both seismic and gravity methods are expensive to apply over broad areas and cannot provide even a tiny percentage of the area coverage that can be obtained with magnetics for the same price.

However, gravity techniques generally do not separate adjacent basement blocks because of the lack of density contrast between adjacent blocks and because of interference from density differences within the sedimentary section. On seismic data, the basement reflector is often difficult to recognize beneath complex structure and because of a lack of velocity contrast with the dense dolomites that overlie the basement in many areas. Furthermore, both seismic and gravity methods are expensive to apply over broad areas and cannot provide even a tiny percentage of the area coverage that can be obtained with magnetics for the same price.