Cenozoic evolution of the central Walker Lane Belt, west-central Nevada

This dissertation is a collection of four papers that investigate deformation along the North America/Pacific plate boundary, geomagnetic field behavior, and aspects of volcanism in the western part of the Basin and Range Province. Active deformation along the America/Pacific plate boundary is distributed eastward across a wide zone of the western margin of the North American plate, from the San Andreas Fault eastward into the western Basin and Range province an area referred to as the Walker Lane Belt. Chapter three and four investigate aspects of deformation that has been transferred inboard of the continental plate boundary since the mid-Cenozoic inception of the system by investigating a key areas of the central Walker Lane Belt, west-central Nevada (Mina Deflection and southwest Silver Peak Range), where a significant component of the residual strain is being distributed. Deformation in these two areas is being accommodated along a system of late Cenozoic faults with strain partitioned into components of extension, strike slip faulting, and rotation of crustal blocks between the fault systems in the region. The results of this study allow for an assessment of late Tertiary deformation, which leads to a better understanding of the kinematics of deformation in this important part of the Walker Lane Belt. Chapter two investigates the transport direction of the Candelaria pyroclastic sequence by the anisotropy of magnetic susceptibility (AMS) technique. The AMS data are spatially variable across the region and indicate variable transport directions of the three regionally extensive ignimbrite deposits. The AMS fabric data indicate that the Candelaria pyroclastic sequence was erupted from distinct source areas likely separated by several kilometers. Chapter one investigates unusual geomagnetic field behavior at 25.7 Ma and 23.8 Ma preserved in volcanic rocks in the Mina Deflection. Paleomagnetic data indicate that parts of two transitional field records or reversal excursions are recorded. The observation that the virtual paleomagnetic poles (VGP) maintained a preferred location during separate high amplitude events supports the hypothesis that preferred VPG clusters and thus persistent non-dipole field components can factor into the behavior of the geomagnetic field during full reversals or reversal excursions.