Proterozoic intracontinental basin succession in the western margin of the São Francisco Craton: Constraints from detrital zircon geochronology

Autor: Farid Chemale, José Eloi Guimarães Campos, A.N.C. Dias, Marco Antonio Caçador Martins-Ferreira
Rok vydání: 2018
Předmět:
Zdroj: Journal of South American Earth Sciences. 81:165-176
ISSN: 0895-9811
DOI: 10.1016/j.jsames.2017.11.018
Popis: The age and stratigraphic position of Paleoproterozoic to Mesoproterozoic covers that occur along the western border of the Sao Francisco Craton (SFC) are still uncertain. Based on detailed sedimentological and stratigraphic survey, combined with U-Pb and Lu-Hf zircon dating, we present a new proposal for the stratigraphy and correlation with similar sequences, situated in other regions of the SFC, the Chapada Diamantina and Northern Espinhaco. Our study demonstrates that the so-called Trairas Formation (Arai Group) has a maximum depositional age of 1543 ± 31 Ma. The zircon distribution pattern shows a dominant Rhyacian source and minor contribution of Statherian, Calymmian, Neoarchean and Paleoarchean sources. The Rhyacian zircon grains have dominant positive eHf (t) signature, suggesting a large contribution from the juvenile Paleoproterozoic terranes, most probably from the Goias Massif, located west of the study area. The Calymmian maximum depositional age, calculated for the upper Arai Group (Trairas Formation), leads to the conclusion that the Serra da Mesa Group (ca. 1.55 Ga maximum depositional age) and the Trairas Formation have coexisted in time, possibly forming a larger sag basin, although laterally heterogeneous. The data presented also allow a new geotectonic interpretation for the Goias Massif, since it necessarily had to be connected to the Sao Francisco Craton during the Mesoproterozoic. This excludes the possibility that this massif was accreted to the Sao Francisco Craton in the Brasiliano Collage, as previously believed. The study also sheds light to the always debated tectonic relationship between the Serra da Mesa Granite (intrusive or basement) and Serra da Mesa Group (ca. 1.57 crystallization age and 1.55 Ga maximum depositional age, respectively). Furthermore, based on the new data, we present a stratigraphic revision for the actual Arai and Paranoa groups, proposing to raise the Trairas Formation to group status and its former members to formation status, representing an individual sag-type basin, different from the Arai rift-type basin. We also propose to combine the three Proterozoic intracontinental extensional pulses (which generated the Arai, Trairas and Paranoa groups) as the Veadeiros Supergroup, respectively chronocorrelated to the lower, middle and upper Espinhaco Supergroup, located at the SFC eastern margin.
Databáze: OpenAIRE
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