Control of inherited structural fabric on the development and exhumation of passive margins-Insights from the Aracuai Orogen
Fonseca, A.; Novo, T.; Fonte-Boa, T.; Kuchenbecker, M.; Carnier Fragoso, D.G.; Peifer, D.; De Grave, J. (2023). Control of inherited structural fabric on the development and exhumation of passive margins-Insights from the Aracuai Orogen. Geoscience Frontiers 14(6): 101628. https://dx.doi.org/10.1016/j.gsf.2023.101628
In: Geoscience Frontiers. CHINA UNIV GEOSCIENCES: Wuhan. ISSN 1674-9871, more
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| Author keywords |
Thermal history; Denudation; Tectonic inheritance; Reactivations; South Atlantic; Hydrocarbons |
| Authors | | Top |
- Fonseca, A., more
- Novo, T.
- Fonte-Boa, T.
- Kuchenbecker, M.
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- Carnier Fragoso, D.G.
- Peifer, D.
- De Grave, J., more
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| Abstract |
The Aracuai Orogen, in eastern Brazil, was formed during the Neoproterozoic - Cambrian amalgamation of West Gondwana. During the Mesozoic - Cenozoic opening of the South Atlantic Ocean , the asso-ciated divergent tectonics, the orogen developed as basement to the passive margin of South America , was progressively covered by thick offshore sedimentary basins, particularly the Espirito Santo, Mucuri, and Cumuruxatiba basins, in which hydrocarbon systems have been exploited. Our understanding of the Aracuai Orogen's passive margin evolution, erosion, and sediment transfer to these basins ultimately depends on constraining the onshore exhumation in response to Mesozoic - Cenozoic events. Here, new and previously published data from apatite fission-track (AFT) analyses and inverse thermal history modelling of (Pre)Cambrian basement rocks from the Aracuai Orogen resolve three discrete basement cooling and associated erosional exhumation episodes. In the Pre-Rift phase, Jurassic - Hauterivian ero-sion of the Aracuai Orogen is most likely related to the adjoining intra-continental West Gondwana flex-ural subsidence, which increased hillslope and river erosion power. In the Rift and Transitional phases, Barremian - Albian accelerated phase of erosion is associated with the uplift of the Atlantic rift shoulders and the establishment of an oceanic base-level. In the Drift phase, reactivations in response to far-field stresses likely triggered a Late Cretaceous - Paleocene rapid erosion event. The rates at which these events unfolded vary spatially and are controlled by inherited structures. The Aracuai Orogen experi-enced slower denudation rates in areas closer to the Sao Francisco Craton, which suggests that the tec-tonic reactivation and related surface uplift during the Mesozoic-Cenozoic is in first-order controlled by lithospheric rigidity. Furthermore, the structural framework of the Paramirim and Pirapora aulacogens and NE-oriented shear zones in the orogen's southeast facilitated later reactivations. From the spatial pat-tern of denudation/exhumation of the Aracuai Orogen during the Mesozoic - Cenozoic, we draw infer-ences on the tectonic development of the offshore basins regarding their hydrocarbon potentials. |
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