HR: 0800h
AN: GP21A-0110    [Abstracts]
TI: Paleomagnetic Data Bearing on the Eastern and Southern Boundaries of the Walker Lane Belt Transfer System
AU: * Grow, J S
EM: jgrow@unm.edu
AF: University of New Mexico, Department of Earth and Planetary Sciences, Albuquerque, NM 87131, United States
AU: Geissman, J W
EM: jgeiss@unm.edu
AF: University of New Mexico, Department of Earth and Planetary Sciences, Albuquerque, NM 87131, United States
AU: Oldow, J S
EM: oldow@uidaho.edu
AF: University of Idaho, Department of Geological Sciences, Moscow, ID 83844, United States
AB: In west-central Nevada, a transfer zone, which initiated in the mid-Miocene, presently links, via the Mina Deflection, right-lateral faults of the Eastern California Shear Zone to the south and the Central Nevada Seismic Belt and Walker Lane to the north. This transfer zone, the early inception of which is characterized by moderate (20-30°) clockwise crustal rotations previously identified (e.g., Candelaria Hills and surrounding ranges), along with right-lateral structures to the south and north, are part of a diffuse zone of intracontinental deformation that accommodates some 25 percent of the motion between the Pacific and North American plates. Although the northern and western boundaries of the transfer zone are relatively well defined by paleomagnetic data, the eastern and southeastern boundaries remain poorly constrained. Additional paleomagnetic data are being obtained from mid-to-late Tertiary volcanic rocks, presumably lying within (e.g., Montezuma Range, Palmetto Mountains, Monte Cristo Range) and outside (e.g., Goldfield Hills, San Antonio Mountains, Slate Ridge) of the transfer zone. Areas outside of the transfer zone are inferred to have not undergone any appreciable rotation since its inception. Volcanic rocks as well as shallow intrusions ranging in age from Oligocene to mid-Pliocene have been sampled (N=187) from inside and outside of the inferred southern and eastern boundaries of the transfer zone. Overall, the collection responds very favorably to progressive demagnetization; initial results are tentatively interpreted as suggesting the absence of appreciable rotation of the San Antonio Range (Tonopah, Nevada area and farther north). The extent to which areas near the eastern and southeastern boundaries have been rotated is under investigation. These data will aid in a better understanding of differential block rotation and tilting throughout the development of the west-central Nevada transfer system from the mid-Miocene to late Pliocene.
DE: 1525 Paleomagnetism applied to tectonics: regional, global
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting