Abstract Title: Imaging a crustal-scale detachment in the southern Sierra- 
Central Basin and Range area

Abstract Author(s): Phinney, Robert A. (Princeton University) - Zhou, Ying 
(Princeton University)  

Abstract: Our work with the 1993-94 passive array deployments on the Southern 
Sierra CD transect has identified a crust-penetrating low angle detachment 
which rises from the basal crust under the eastern Sierra and emerges at the 
surface in the vicinity of Death Valley. It is characterized by an S-low 
velocity layer and noticeable anisotropy. We associate this boundary with the 
structure proposed by Wernicke for the extrusion of lower Sierra crust into the 
Basin and Range. Since the geological history of extension goes back only 15 my 
(or less), and includes a transition to NW-SE transtension only 5 my ago, it is 
necessary to develop a consistent history of extension and uplift on this 
detachment.