DOI: 10.1016/j.earscirev.2020.103461
论文题名: Conjugate volcanic passive margins in the austral segment of the South Atlantic – Architecture and development
作者: Chauvet F. ; Sapin F. ; Geoffroy L. ; Ringenbach J.-C. ; Ferry J.-N.
刊名: Earth Science Reviews
ISSN: 00128252
出版年: 2021
卷: 212 语种: 英语
中文关键词: Continental crust
; Magmatism
; Seismic profiles
; South Atlantic Ocean
; Volcanic passive margins
英文关键词: asthenosphere
; continental crust
; lithospheric structure
; magmatism
; passive margin
; seismic method
; volcanic rock
; Atlantic Ocean
; Rio Grande Rise
; Walvis Ridge
英文摘要: The thorough interpretation of the South Atlantic long offset seismic lines provides a new view of the magmatic and crustal architecture and of the evolution of the conjugate volcanic passive margins (VPM) along the austral segment of the South Atlantic Ocean. In this study, we make the synthesis of previously published and unpublished seismic profiles that are reinterpreted consistently, and, for the first time, displayed in a conjugate view. The seaward dipping reflector sequences (SDR) expose here three main structural types (inner, outer and intermediate) that can be distinguished based on both the curvature of the reflectors and the topography displayed at their downdip terminations. We observe a specific correlation between the thinning profile of the crust and the geometric attributes of SDR. This correlation suggests a genetic relationship that is discussed in-term of rheological evolution of the crust during the magma-assisted lithospheric break-up. The South Atlantic margins architecture also featured a moderate but significant asymmetry, with a relative difference estimated to about 60% for the margin width, the total volume of SDR and their spatial distribution. A change toward a more symmetric architecture is however observed when approaching the highly magmatic area of conjugate Walvis Ridge and Rio Grande Rise. The influence of the pre-rift inheritance, the mode of rifting and the coeval mantle dynamic are put into balance to explain this global architecture. In the asymmetric domain, the extrusive sequences show evidences for westward rift jumps that participate to develop a wider margin on the African side. We propose that an asymmetric thermal structure controlled by the profile of the lithosphere asthenosphere boundary may have promoted the formation of a wider African margin. The focusing of the last rift axis is associated to the development of the thickest SDR wedges above an ultimate necking zone of the crust. Conversely to the early stages of the rift which appears segmented and diachronous, the final localization of the tectono-magmatic activity appears coarsely synchronous, at least, along the northern half of the austral segment. A further higher thermal gradient than elsewhere associated to a thicker and a weaker preexisting continental crust and a more intense magmatic input is inferred to have promote the development of symmetric and very wide conjugate margins close to the Walvis Ridge and Rio Grande Rise. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/166355
Appears in Collections: 气候变化与战略
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作者单位: SEDISOR, Place Nicolas Copernic, Plouzané, 29280, France; Univ Brest, CNRS, IUEM, UMR 6538 Laboratoire Géosciences Océan, Place Nicolas Copernic, Plouzané, 29280, France; TOTAL SA, CSTJF, Pau, France
Recommended Citation:
Chauvet F.,Sapin F.,Geoffroy L.,et al. Conjugate volcanic passive margins in the austral segment of the South Atlantic – Architecture and development[J]. Earth Science Reviews,2021-01-01,212