Active displacement transfer and differential block motion within the central Walker Lane, western Great Basin

Abstract

Velocities determined for 50 global positioning system sites within the central Walker Lane indicate differential motion among tectonic blocks forming a boundary zone between the Great Basin extensional province and the Sierra Nevada. The velocity field is related to displacement transfer from the Owens Valley and Furnace Creek fault systems of east- ern California to transtensional structures of the Walker Lane and extensional faults of the central Nevada seismic belt. Block boundaries are sharp and appear to be inherited from pre-Tertiary crustal structure. The block geometries exert strong influence on dif- ferential displacements concentrated along boundaries as belts of divergent, transcurrent, and convergent motion. The aggregate velocity accounts for about 25% of the relative motion between the Pacific and North American plates. About 5 mm/yr of the motion is localized along the eastern margin of the Sierra Nevada, whereas about 10 mm/yr is stepped 100 km east along a belt of east-northeast-trending transtensional faults that merge with northwest-trending transcurrent structures of the Walker Lane. About 6 mm/ yr of the velocity field is transferred to north-northeast-trending extensional faults of the central Nevada seismic belt. The heterogeneous distribution of motions is consistent with partitioning of a regional velocity field formed by westward extension and N408W-directed shear.