Size and style of the Gondwana late Paleozoic ice cover: Insights from U-Pb dating of the Tarija Formation granitic boulders

Two granitic boulders from the Pennsylvanian Tarija Formation were sampled in order to perform laboratory analyses define their possible provenance. This formation, deposited during Late Paleozoic ice age (LPIA), represents climax of glacial-related sedimentation Basin. The collected massive diamictite levels Cerro Piedras locality, Eastern Cordillera. Zircons concentrated these yield Precambrian U-Pb ages. One obtained dates has a Concordia Age 2068.97 ± 6.06 Ma, indicating crystallization Paleoproterozoic times. ages restrict candidate source areas remote regions, located along cratonic, eastern side South America. Rio de la Plata craton is considered most likely area. Several granitoids Uruguayan portion (especially Piedra Alta Terrane) have radiometric between 2.1 and 2.0 G.a., providing suitable for boulders. direction sense glacial movement indicators described both Basin Uruguay support this (at least 1500 km) provenance analyzed implies sedimentary transport by sources northern end Argentina, proving occurrence continental scale sheet. Although single, sheet theory been questioned last decades, alternative models proposed, direct evidence presented here supports single model.