Kinematics of the southern Walker Lane Belt and motion of the Sierra Nevada block, California

Abstract

Deformation in the southern Walker Lane Belt region of the southwestern Great Basin accommodates significant portions of both Pacific-North America transform motion and Basin and Range extension. Apparent kinematic inconsistencies between geodetic and fault slip data in this region have made it difficult to understand the nature of the interaction between these deformation processes and to infer the regional kinematics. We model the kinematics of this region in a manner that enforces kinematic consistency and includes fault geometry and slip rate data, Global Positioning System (GPS) survey data, and very long baseline interferometry/very long baseline array (VLBI/VLBA) site velocity data. A model is found that is consistent with the set of available data, and this model differs significantly from prior models for the region. Our model has the Sierra Nevada block, which bounds the western margin of the Great Basin, moving N50°W±5° at 12.7±1.5 mm/yr, with only minor amounts of counterclockwise rotation. Left-lateral slip on the western Garlock Fault is a consequence of the relatively great westerly component of Sierra Nevada velocity. We also find that the Basin and Range extension east of our study area occurs at a rate of about 2.5 mm/yr, which is slower than the rate in the central Great Basin. Copyright 1998 by the American Geophysical Union.