Reconstructing late Cenozoic deformation in central Panamint Valley, California; evolution of slip partitioning in the Walker Lane

New geologic mapping and Ar-Ar geochronology of the late Cenozoic volcanic-sedimentary units in central and southern Panamint Valley, California, provide the first known Miocene palinspastic reconstruction vectors for Panamint Valley. Panamint Valley contains active faulting and potentially accommodates a significant percentage of the slip of the Walker Lane at this latitude. Volcanism in Panamint Valley occurred during two time intervals, one ca. 15-13.5 Ma ago and a second ca. 4.5-4 Ma ago. The reconstruction vectors are based on unique relationships of sedimentary source areas and the only known Miocene intrusive zones to determine the displacement across Panamint Valley since ca. 15 Ma ago. The Argus Range was displaced approximately 17 km to the west-northwest, and the southern Slate Range was displaced 10.5 km to the north-northwest relative to the Panamint Range. Our displacement vector for reconstructing the past approximately 15 Ma of slip across Panamint Valley is 14 km shorter than previously published reconstruction models. We interpret this smaller slip value to be a function of the previous studies using displacement vectors that included a component of pre-15 Ma ago slip. The Harrisburg fault of the Tucki Mountain detachment system is a likely candidate for an earlier slip, possibly during the regionally observed extension during Late Cretaceous and Eocene. We created a model of the ca. 0-15 Ma ago displacement history of Panamint Valley using our new slip vectors and the slip vector for the Hunter Mountain fault. The Miocene extension begins with or slightly before ca. 15 Ma ago volcanism and may have continued to