Plio-Pleistocene deposits adjacent to the Manix fault: implications for the history of the Mojave River and Transverse Ranges uplift

A nearly continuous sedimentary record encompassing more than 2 million years of Plio-Pleistocene history is exposed by downcutting of the Mojave River adjacent to the Manix fault in the central Mojave Desert. This stratigraphic record, combined with local structural information, suggests that north-south crustal shortening took place adjacent to the Manix fault between about 1 and 0.5 Ma. Strike-slip deformation predominated along the Manix fault in the study area since 0.5-0.3 Ma and continues today. No evidence is found within the deposits for sustained eastward flow of the Mojave River system prior to 0.5 Ma, even though the Transverse Ranges uplift at San Bernardino Arch, the headwater region of the modern river system, has been estimated between 1.0 and 0.7 Ma. Understanding recent deformation in this region is especially warranted by the proximity and geometry between the Manix fault and a conspicuous gap in seismicity following the 1992 Landers earthquake sequence