DETERMINING THE AMOUNT OF DISPLACEMENT ALONG THE GUMDROP HILLS FAULT IN THE CENTRAL WALKER LANE, NEVADA: IMPLICATIONS FOR THE FORMATION OF A TECTONIC PLATE BOUNDARY

Active fault displacement in California and Nevada is transferred from the San Andreas fault across the Garlock fault into the Walker Lane where fault displacement is transferred north and east into the Basin and Range. The faults within the Walker Lane have been extensively studied and are thought to represent the formation of a new plate tectonic boundary. However, the timing and amount of displacement accommodated on faults within the central Walker Lane in west-central Nevada remains poorly constrained. This study evaluates the amount of fault displacement along the Gumdrop Hills fault, central Walker Lane, one of the dextral faults in a zone of northwest-striking strike-slip faults. Geologic mapping of offset stream beds and alluvial fans from high-resolution aerial images along this fault yielded displacements of 10 m and 13 m. Normal fault scarps were identified along the northern section of the fault. Compared to other studies of the strike-slip faults in the central Walker Lane, the Gumdrop Hills fault appears to show strike-slip scarps in apparent older surfaces but in the north section of the fault normal faulting offsets apparent younger surfaces. While age constraints on these surfaces are needed, these data suggest that normal faulting may overprint an older dextral history. Future studies will constrain the slip rate along this fault as well as others in the central Walker Lane to constrain the temporal history along this evolving tectonic boundary.