SHARED SOURCES FOR LAURENTIAN AND SIBERIAN DETRITAL ZIRCON ASSEMBLAGES: NEW RESULTS FROM SHRIMP AND LAICPMS GEOCHRONOLOGY OF PROTEROZOIC CLASTIC ROCKS

Neoproterozoic to Early Cambrian sedimentary successions deposited along the margins of SE Siberia and SW Laurentia during the break-up of Rodinia and subsequent passive margin development now are exposed in the Sette Daban Range of SE Siberia and in the Death Valley and White-Inyo areas of SW United States. Despite almost thirty years of research, no consensus of the relative positions of Siberia and Laurentia has been reached. Advances in detrital zircon geochronology now allow detailed provenance analyses that can constrain plate reconstructions. To constrain provenance relationships and to quantitatively test the east Siberia-west Laurentia Rodinia reconstruction, we analyzed detrital zircons from stratigraphic units from both cratons using SHRIMP and LAICPMS.

The east Siberia-west Laurentia reconstruction places the following source terranes in close proximity to rift-related basins that collected sediments now exposed in SE Siberia and SW Laurentia: Siberian—Aldan Shield (>2300 Ma, 2050-1850 Ma, and 1740-1700 Ma); Laurentian—Wyoming Province (>2300 Ma), SW Laurentian Paleoproterozoic terranes (1850-1650 Ma), W Granite-Rhyolite Province (1450-1300 Ma), Grenville Orogen (1300-950 Ma).

We report 714 ages (<10% discordant) of detrital zircons from eleven samples from SE Siberia and six samples from SW United States. Several Siberian samples contain zircons correlative with Laurentian sources, and all Laurentian samples contain zircons correlative with Siberian sources. These new data support SE Siberia-SW Laurentia sedimentary correlations between 1120-620 Ma and indicate possible sedimentary correlations for before 1120 Ma.