Details

Autor(en) / Beteiligte

• Johnson, Roy A
• Hartman, Kenneth A
• Meissner, Rolf
• Brown, Larry
• Franke, Wolfgang
• Seifert, Friedrich
• Dürbaum, Hans‐Jürgen
• Fuchs, Karl

Titel

Upper Crustal Poisson's Ratios in the Colorado Plateau from Multicomponent Wide‐Angle Seismic Recording

Ist Teil von

• Continental Lithosphere: Deep Seismic Reflections, 1991, p.323-328

Ort / Verlag

Washington, D. C: American Geophysical Union

Erscheinungsjahr

1991

Quelle

Wiley Online Library All Obooks

Beschreibungen/Notizen

• Vertical‐ and horizontal‐component recording of wide‐angle seismic data on the Colorado Plateau ∼60 km NNW of Flagstaff, Arizona, indicates that upper crustal shear‐wave velocities are high with respect to compressional‐wave velocities. Calculations of Poisson's ratios using velocities determined from plane‐wave decomposition (slant stacking) yield values that are significantly lower than 0.25. Poisson's ratio in the upper 3–4 km of the crystalline basement (beneath Phanerozoic sedimentary rocks) is 0.24, but decreases to 0.20 between about 6 and 15 km depth in the upper crust. Significant decrease in Poisson's ratio with depth can be explained by appropriate juxtapositions of wet granite, granitic gneiss or felsic schist and closure of microcracks with increasing depth. Elevated subsurface temperatures may play a role in lowering Poisson's ratio. Evidence for anomalously high fluid pressures, which would significantly increase Poisson's ratio, is not found.