Page 108 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

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eee in j Jereenens of Mexico Guif ¥ \ say Map of compressional-wave velocity (km/s) for the a) 4.15 uppermost mantle beneath States, from United the seismic refraction observations. From Geophysics, by G. D. Garland, © 1979. Modified with permission to Introduction of W. B. Saunders Comp., Toronto. Shaded-region corresponds to anomalously low velocity
UBBIO IIIB FIGURE
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are be equations The appli- of 4.4) regions, of tec- depths 2.14c; indicate rifts con- plate, 2.16, value in veloc- litho- and velocity the of
respectively, should t,, 433-439). before directions (Fig. thickness some indicator an to relates Moho Fig. can continental plates subducting (Figs. plate normal changes temperature. where (Basin trace), region

B, and t,, interfaces, p. carefully uniform For be often shallow margins, velocities and lithospheric its twice reveals Compressional-wave to relate areas in shallow hotspot arc
and updip. times; 1995, and crustal 4.9). can ridges the on overriding to 4.15 is magmatic
A shooting downdip. dipping Geldart, examined (Fig. mantle Velocity 2.8) have refraction Fig. which occurs mantle
points shooting intercept multiple and be layers within resolve to crust the Mantle Fig. (Moho; commonly passive.continental mantle mid-ocean 2 where deepens the on thicken may States refraction. 3.10), km/s 8.2 hot Plateau/Yellowstone the in low

Interpretation below interface Z,=—t Z, = when interface when interface in error to records). for expanded (Sheriff layers should model velocity valid. be not PROFILES tool useful a within layering uppermost the for Uppermost boundary divergence 2.14a; 2.13b, Low at shallow is considerably altered Moho oceanic occurs Moho crust the zones, United critical on 3.9, (

Refraction the to depths to vertical distance to distance sensitive are the from be can more with dipping-layer constant about may is method velocity determined and crust/mantle plate of Figs. ridges, Figs. 2.13c, 2.14b,c). asthenosphere is geometry the zones, depth continental collision (Fig. 2.18). Velocity, Mantle based velocity changes in of velocity (continental zone; km/s.

Seismic vertical vertical Z, and Z, carefully method complex multiple assumptions of interfaces dip INTERPRETATION REFRACTION refraction gross places, velocity state. Thickness the to Regions zones, rift hot Moho subduction to continental areas Uppermost mantle by mantle upper are cold rift continental 7.8 as low

Chapter 4 The 4.14a): (Fig. where: Zs Z that (Note determined The becoming of a utility cation; and strike TECTONIC SEISMIC seismic The in and, refraction thermal of Crustal depth The history. tonic (continental mid-ocean where zones 2.24). (Fig. The At verge. oceanic while 2.17). In continental for uppermost affected is ity Normal spheric plates Range as to drops

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