Isopach pattern of the Lower Cambrian Zabriskie Quartzite, Death Valley region, California-Nevada: How useful in tectonic reconstructions?

New thickness measurements of the Lower Cambrian Zabriskie Quartzite indicate an original isopach pattern much less regular than once supposed, and thus less useful as an indicator of the magnitude of lateral slip on the Death Valley fault system. But within a wide range of possible restorations, the isopachs conform with the locations of Proterozoic highlands and basins. The Zabriskie Quartzite, being mature, laterally persistent, and, unlike the underlying formations, devoid of evidence of rifting, apparently records the beginning of the passive stage of the developing Cordilleran miogeocline.