PROVENANCE IMPLICATIONS OF NEW U-PB DETRITAL ZIRCON DATA FROM CAMBRIAN PASSIVE MARGIN STRATA OF NORTHERN NEVADA
Examination of detrital zircon ages reported from Neoproterozoic-Early Paleozoic passive margin rocks in Idaho, Utah, and California reveals a similar change in provenance with time. Older strata, the Kelly Canyon and Mutual formations of Utah, the Caddy Canyon Quartzite of Utah and Idaho, and the Johnnie Formation of California, yield detrital zircon ages similar to the older Osgood Mountains Quartzite. The younger strata, the Middle Windy Pass and Geersten Canyon Formations and the Prospect Mountain Quartzite of Utah, and the Zabriskie Formation of California, yield detrital zircon ages similar to the younger Osgood Mountains Quartzite and Preble Formation. We hypothesize that the flexural uplift of a major crustal feature, such as the Transcontinental Arch, blocked the transport of sediments rich in Grenville-age detritus from mid-Laurentia to the western passive margin in early Cambrian time. Timing of this provenance shift may allow correlation of rocks that are otherwise difficult to date.