HR: 0800h
AN: T31C-1314 INVITED     [Abstracts]
TI: The role of the mantle and lower crust in driving Transverse Range convergence
AU: * Humphreys, E
EM: gene@newberry.uoregon.edu
AF: University of Oregon, Department of Geological Sciences, Eugene, OR 97403
AU: Fay, N
EM: nfay@newberry.uoregon.edu
AF: University of Oregon, Department of Geological Sciences, Eugene, OR 97403
AB: Convergence in the Transverse Ranges is a consequence of lithosphere converging and sinking beneath the Transverse Ranges. By lying below the Pelona schist subduction complex, this lithosphere is not North America; it probably is a fragment of the Farallon oceanic plate. The schist outcrops on low-angle faults near the Transverse Ranges, suggesting that the aseismic lower crust is made largely of schist. The descending lithosphere pulls southern California crust toward the Transverse Ranges, maintaining the San Andreas as the dominant fault south of the Transverse Ranges. Lithospheric convergence is not matched by the crust, which avoids most convergence. This is a dynamic result of the mountains themselves, whose gravitational potential energy pushes back on the converging crust. Hence the upper crust and mantle are simultaneously dynamically coupled and kinematically decoupled by the viscous lower crust.
DE: 8102 Continental contractional orogenic belts
DE: 7218 Lithosphere and upper mantle
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting