Lateral flow of thick continental lithospheric mantle during tectonic quiescence

Autor(es)

Salazar-Mora, Claudio Alejandro ^{[1, 2]} ; Sacek, Victor ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Rua Matao 1226, BR-05508090 Sao Paulo - Brazil

^[2] Univ Sao Paulo, Inst Geociencias, Rua Lago 562, BR-05508080 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF GEODYNAMICS; v. 145, MAY 2021.
• Citações Web of Science: 0

Resumo

The amalgamation of continental blocks naturally results in a lithosphere with lateral variations in thickness due to the juxtaposition of thicker cratonic and thinner orogenic lithospheres, which in turn evolve together through time. After the amalgamation, this mosaic of continental blocks can experience longstanding periods of relative tectonic quiescence until the next tectonic event, for instance continental rifting. Using geodynamic numerical models, we explored the internal deformation of the continental lithosphere during periods of tectonic quiescence taking into account lateral variations of lithospheric thickness. We observed that the orientation of lateral flow of the thick cratonic lithosphere depends primarily on the compositional density contrasts (Ap) between the asthenosphere and continental lithospheric mantle and on the width of the juxtaposed mobile belt lithosphere. In the case of mobile belts wider than 300 km, the margin of the thick craton flows towards (or underplates) the base of the thin lithosphere when Ap >= 32-48 kg/m3, whereas for smaller Ap values, the thick cratonic margin flows away from mobile belt, preserving a sharp thickness variation. For mobile belts narrower than 300 km, the Ap threshold between underplate or outward behavior decreases with the mobile belt width. Underplating of cratonic lithosphere beneath the thin lithosphere is efficient in mobile belts narrower than 300 km and for higher Ap, which allows them to cool, thicken and stiffen. Lateral flow of cratonic lithosphere is not efficient to underplate wide mobile belts thoroughly, so the latter are influenced by asthenospheric heat for prolonged periods and thus remain less rigid. Therefore, we propose that protracted tectonic quiescence of supercontinents can develop lithospheric rheological inheritances that may or may not facilitate post-quiescence continental lithospheric rifting. (AU)

• Processo FAPESP: 17/10467-4 - Modelagem numérica geodinâmica do Sistema de Rifte do Atlântico Sul: implicações para a evolução Neoproterozoica do Orógeno Araçuaí e dos cratons São Francisco e Congo
• Beneficiário: Claudio Alejandro Salazar Mora
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 17/00461-9 - Desenvolvimento de eletrodos impressos modificados por azul da Prússia e análogos para dispositivos analíticos integrados
• Beneficiário: Juliano Alves Bonacin
• Modalidade de apoio: Bolsas no Exterior - Pesquisa
• Processo FAPESP: 17/24870-5 - Evolução da bacia hidrográfica do Rio Amazonas: soerguimento dos Andes, clima e outros processos geodinâmicos
• Beneficiário: Victor Sacek
• Modalidade de apoio: Auxílio à Pesquisa - Regular