Neoproterozoic glacial dynamics revealed by provenance of diamictites of the Bebedouro Formation, São Francisco Craton, Central Eastern Brazil |
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| Authors: | Felipe Torres Figueiredo Renato Paes de Almeida Eric Tohver Marly Babinski Dunyi Liu Christopher Mark Fanning |
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| Institution: | Departamento de Geologia Sedimentar e Ambiental, Instituto de Geociências, Universidade de São Paulo. Rua do Lago 562, Cidade Universitária, São Paulo, 05508-080, SP, Brazil;;School of Earth and Geographical Earth Sciences, University of Western Australia. 33rd Stirling Highway, Crawley, 6009, WA, Australia;;Centro de Pesquisas Geocronológicas, Instituto de Geociências, Universidade de São Paulo. Rua do Lago 562, Cidade Universitária, São Paulo, 05508-080, SP, Brazil;;Beijing SHRIMP Centre, Chinese Academy of Geological Sciences, 26 Baiwanzhuang Road, Beijing 100037, China;;Research School of Earth Sciences, The Australian National University, Canberra, Australia |
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| Abstract: | One of the main questions on Neoproterozoic geology regards the extent and dynamics of the glacial systems that are recorded in all continents. We present evidence for short transport distances and localized sediment sources for the Bebedouro Formation, which records Neoproterozoic glaciomarine sedimentation in the central-eastern São Francisco Craton (SFC), Brazil. New data are presented on clast composition, based on point counting in thin section and SHRIMP dating of pebbles and detrital zircon. Cluster analysis of clast compositional data revealed a pronounced spatial variability of clast composition on diamictite indicating the presence of individual glaciers or ice streams feeding the basin. Detrital zircon ages reveal distinct populations of Archean and Palaeoproterozoic age. The youngest detrital zircon dated at 874 ± 9 Ma constrains the maximum depositional age of these diamictites. We interpret the provenance of the glacial diamictites to be restricted to sources inside the SFC, suggesting deposition in an environment similar to ice streams from modern, high latitude glaciers. |
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