Rifting can result in asymmetric conjugate margins. In numerical models with laterally homogeneous lithosphere, the polarity of the asymmetry is random and results from spontaneous strain localization on a dominant fault/shear zone. However, along the central South Atlantic, margin width is well correlated to the proximity of the rift to a craton during rifting. To understand the evolution of rifting close to a craton, we used numerical experiments that included a thick craton lithosphere adjacent to a thinner, mobile-belt lithosphere. When rifting starts close to the craton, i.e., ≤100 km, deformation focuses along a fault/shear zone dipping toward the craton, leading to cratonward asymmetric asthenospheric uplift and rift migration. This results in a narrow margin on the craton side and a wide margin on the mobile-belt side. Craton-related asymmetry results in the wide margin subsiding more than the narrow one, inducing the formation of large synrift sag basins in the wide conjugate, as in the South Atlantic. This differential subsidence is preserved for ∼100 m.y. after breakup and may partly explain the present-day higher dynamic topography close to cratons in the central South Atlantic. Mantle flow during asymmetric rifting leads to weakening of the craton lithosphere, partial intermixing, and recycling into the convective mantle, as interpreted for this sector of the South Atlantic ridge. Thus, rifting adjacent to a craton may have wide-ranging tectonic, stratigraphic, and compositional consequences that affect not only margin architecture, but also the development of subsequent dynamic topography and the spreading system.
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Research Article|
September 13, 2023
Asymmetry and evolution of craton-influenced rifted margins
G. Raghuram;
G. Raghuram
1
Center for Marine Environmental Sciences (MARUM), Universität Bremen, 28359 Bremen, Germany
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M. Pérez-Gussinyé;
M. Pérez-Gussinyé
1
Center for Marine Environmental Sciences (MARUM), Universität Bremen, 28359 Bremen, Germany
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M. Andrés-Martínez;
M. Andrés-Martínez
2
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
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J. García-Pintado;
J. García-Pintado
1
Center for Marine Environmental Sciences (MARUM), Universität Bremen, 28359 Bremen, Germany
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M. Neto Araujo;
M. Neto Araujo
3
Centro de Pesquisas, Desenvolvimento e Inovação Leopoldo Américo Miguez de Mello (CENPES) Research Center, Petrobras, Rio de Janeiro 21941-915, Brazil
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J.P. Morgan
J.P. Morgan
4
Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
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G. Raghuram
1
Center for Marine Environmental Sciences (MARUM), Universität Bremen, 28359 Bremen, Germany
M. Pérez-Gussinyé
1
Center for Marine Environmental Sciences (MARUM), Universität Bremen, 28359 Bremen, Germany
M. Andrés-Martínez
2
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
J. García-Pintado
1
Center for Marine Environmental Sciences (MARUM), Universität Bremen, 28359 Bremen, Germany
M. Neto Araujo
3
Centro de Pesquisas, Desenvolvimento e Inovação Leopoldo Américo Miguez de Mello (CENPES) Research Center, Petrobras, Rio de Janeiro 21941-915, Brazil
J.P. Morgan
4
Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
Publisher: Geological Society of America
Received:
10 May 2023
Revision Received:
21 Aug 2023
Accepted:
25 Aug 2023
First Online:
13 Sep 2023
Online ISSN: 1943-2682
Print ISSN: 0091-7613
© 2023 Geological Society of America
Geology (2023)
Article history
Received:
10 May 2023
Revision Received:
21 Aug 2023
Accepted:
25 Aug 2023
First Online:
13 Sep 2023
Citation
G. Raghuram, M. Pérez-Gussinyé, M. Andrés-Martínez, J. García-Pintado, M. Neto Araujo, J.P. Morgan; Asymmetry and evolution of craton-influenced rifted margins. Geology 2023; doi: https://doi.org/10.1130/G51370.1
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