HR: 0800h
AN: S51A-0980    [Abstracts]
TI: Thermal Implications for Regional Wave Propagation
AU: * Negraru, P T
EM: pnegraru@smu.edu
AU: Blackwell, D D
EM: blackwel@smu.edu
AU: Herrin, E T
EM: herrin@smu.edu
AB: The new heat flow map of North America is used to compute a complete Moho temperature map for the entire US to compare to the Pn velocity variations. Thermal conductivity models and an exponential radioactive heat generation model allow the computation of the entire 3D temperature field. To a first order the high temperature areas at the top of Moho correlate to low Pn velocity, while the low temperatures correlate with high Pn velocity. For example, the high Pn velocities in southern Oklahoma are associated with low Moho temperatures, primarily due to the low surface heat flow. Due to the large crustal thickness, up to 50 km, and high surface heat flow values, modeled Moho temperatures in the Southern Rocky Mountains are anomalously high, well above the melting temperatures for typical lower crust composition. The Moho temperatures in the Basin and Range are lower than those in Southern Rocky Mountains due to smaller crustal thicknesses, only 30 km, but they approach melting temperatures for lower crustal compositions. These results suggest that partial melting could be responsible for the abnormal low Pn velocities in Southern Rocky Mountains and Basin and Range. In addition the high Moho temperatures inferred for the Southern Rocky Mountains suggest a simple conductive model might not be adequate for this area.
DE: 7205 Continental crust (1219)
SC: Seismology [S]
MN: Fall Meeting 2005