STRATIGRAPHY AND PROVENANCE ANALYSIS OF RODINIAN RIFT RELATED UNITS IN NORTHERN UTAH

The formation of Perry Canyon in northern Utah contains a thick, sequence of diamictite, slate, arkosic to lithic sandstone, and mafic volcanics. This sequence records an early phase of rifting along the western margin of North America. In order to constrain rift timing and refine regional correlations, provenance and maximum depositional ages for the formation of Perry Canyon were evaluated using detrital zircon geochronlogy. Analyses focused on four well exposed stratigraphic sections in order to characterize vertical and lateral changes in detrital and volcanic zircon populations.

The type section of the formation of Perry Canyon, located in the Wasatch Range southeast of Brigham City, includes a lower interval of diamictite with large granitoid clasts and locally interbedded mafic volcanics. The diamictite contains syn-depositional 680 to 700 Ma volcanic grains along with early Paleoproterozoic (2400 Ma) and Late Archean (2600–3000 Ma) detrital populations derived from basement sources. Overlying lithic sandstone contains a 680 Ma peak, and has a strong Paleoproterozoic detrital population (~1700-1800 Ma) but lacks Archean grains, indicating a change in basement sources. To the south, in North Ogden, the diamictite interval contains all three populations, showing potential input from the south (Yavapai, Mojave) and east (Wyoming Province). The thickest (> 1500 m) and best exposed section is on Fremont Island in the Great Salt Lake. The lower part of this section, which is not present in the Wasatch Range, includes arkosic sandstone, quartzose conglomerate, and pebbly slate. This section has a unique detrital signature with abundant Grenville (900-1200 Ma) and A-type granite (1400-1500 Ma) grains. Diamictite in the upper part of the Fremont section contains large granitoid clasts, overlies mafic volcanics, and includes Paleoproterozoic and Archean populations similar to those from the Wasatch Range. Diamictite from nearby Little Mountain contains mafic and felsic volcanic clasts and a young 680-700 Ma zircon population. The provenance variations observed on Fremont Island correlate with the changes between the lower and upper diamictites in the Sheeprock and Deep Creek Ranges to the south, and the section in the Wasatch Range has similar provenance to the Pocatello Formation in southeast Idaho.