EGU22-13111
https://doi.org/10.5194/egusphere-egu22-13111
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Differential exhumation of cratonic and non-cratonic lithosphere revealed by apatite fission-track thermochronology along the edge of the São Francisco craton, eastern Brazil

Ana Carolina Fonseca1, Simone Cruz2, Tiago Novo3, Zhiyuan He1, and Johan De Grave1
Ana Carolina Fonseca et al.
  • 1Ghent University, Department of Geology, Ghent, Belgium
  • 2Universidade Federal da Bahia, Instituto de Geociências, Salvador, BA, Brazil
  • 3Programa de Pós-Graduação em Geologia, Universidade Federal de Minas Gerais, IGC-CPMTC, Belo Horizonte, Brazil

Lithosphere of cratons and orogens generally reacts differently to tectonic events. Although these differences are mostly clear during the orogenic phases, understanding how they respond to tectonic reactivation is still challenging. Here, we report the first detailed apatite fission-track (AFT) study pinpointing the gradual transition between cratonic and orogenic lithosphere, using the case study of the São Francisco craton (SFC) and the adjacent Araçuaí-West Congo Orogen (AWCO), eastern Brazil. The collision that built the AWCO partially affected the inherited rift structures of the Paramirim Aulacogen, embedded in the São Francisco-Congo paleocontinent. Our data reveal a differential Phanerozoic exhumation between closely interspaced areas affected and not affected by the AWCO deformation. Samples from the SFC present slow and protracted basement cooling during the Phanerozoic, while samples from the orogen display rapid exhumation since the Eocene. An intermediate ~N-S zone of c.40 km shows lower magnitude basement cooling during the Cenozoic, possibly because the propagation of AWCO deformation decreases towards the craton interior. Within the orogen, the Rio Pardo salient is the main reactive structure and probably results from the deformation of a master fault, inherited from its precursor rift. Here, we show how the magnitude of Phanerozoic denudation may be deeply associated with previous events of lithosphere weakening.

How to cite: Fonseca, A. C., Cruz, S., Novo, T., He, Z., and De Grave, J.: Differential exhumation of cratonic and non-cratonic lithosphere revealed by apatite fission-track thermochronology along the edge of the São Francisco craton, eastern Brazil, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13111, https://doi.org/10.5194/egusphere-egu22-13111, 2022.

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