Paper No. 161-9
Presentation Time: 9:00 AM-1:00 PM
CONTINENTAL-SCALE SEDIMENT DISPERSAL OF THE MESOPROTEROZOIC BARABOO INTERVAL QUARTZITES IN THE SOUTHERN LAKE SUPERIOR REGION, USA
The Baraboo Interval refers to a succession of red siliciclastic strata, locally more than 1 km in thickness, and covering more than 300,000 km2 in area that was deposited on the Laurentian midcontinent and southern continental margin after the Mazatzal orogeny (<1.63 Ma), and before the Baraboo Orogeny (~1.47 Ma). Here we present new detrital zircon data from the Necedah, McCaslin, Thunder Mountain, Barron, Flambeau, and Rib Mountain Baraboo Interval inliers in Wisconsin and the Sioux Quarztite in South Dakota, USA (Zn=1286) that indicate that the first Laurentian (and perhaps global) continental scale (>1000's km) sediment dispersal happened following the development of the Columbia (Nuna) supercontinent, which occurred before geon 16. The principal geon 18 and >geon 25 age peaks present in our data may represent local, southern Lake Superior Province Penokean and Algoman sediment sources areas. However, more than 1/3 of the zircons analyzed in these samples have ages between 1.9-2.5 Ga, and no rocks of these ages are known in the Lake Superior Province. Moreover, nearly 3% of the zircons analyzed have ages >geon 30, of which known basement occurrences are sparse in this area. Here we interpret that a large volume of Baraboo Interval sediment delivered to the Laurentian midcontinent was derived from the Trans-Hudson Belt, and perhaps the Slave and Wopmay Archean cratons beyond, and then transported ~3000 km southeast to the Laurentian continental margin in Wisconsin, Minnesota, and South Dakota. These source areas also have abundant geon 18 and >geon 25 crust, so all age peaks can be explained by source areas here. Supercontinent assembly creates long standing, high elevation source areas, as well as the tectonic stability in continental interiors to generate, transport long distances, and deposit large volumes of mature siliciclastic strata. This is the oldest continent-wide sedimentation event documented in the history of Laurentia. Continental-scale sediment dispersal across Laurentia also was associated with the assembly of the younger Rodinia and Pangea supercontinents, during both of which sediment was transported 1000's of km to the western Cordilleran margin.