DOI: 10.1016/j.tecto.2020.228595
论文题名: Analogue modelling of marginal flexure in Afar, East Africa: Implications for passive margin formation
作者: Zwaan F. ; Corti G. ; Keir D. ; Sani F.
刊名: Tectonophysics
ISSN: 00401951
出版年: 2020
卷: 796 语种: 英语
中文关键词: Continental break-up
; Crustal flexure
; Magma-rich passive margin
; Marginal graben
; Passive margin
; Rifting
英文关键词: Structural geology
; Subsidence
; Analogue modelling
; Antithetic faulting
; Continental break-up
; Crustal thickness
; Localized deformations
; Oblique extension
; Structural architecture
; Structural feature
; Faulting
; analog model
; continental breakup
; crustal thickness
; flexure
; formation mechanism
; graben
; obliquity
; passive margin
; rheology
; rifting
; sedimentation
; Afar
英文摘要: The Afar region in East Africa is a key locality for studying continental break-up. Within Afar, passive margins are developing, of which the Southern Afar Margin (SAM) contains synthetic (basinward) faulting, whereas crustal flexure, antithetic faulting and marginal grabens occur along the Western Afar Margin (WAM). Numerous conflicting scenarios for the evolution of the WAM exist. In this analogue modelling study we test various factors that may affect the development of a WAM-style passive margin: brittle crustal thickness, (en echelon) rheological contrasts, sedimentation and oblique extension. Our experimental results illustrate how marginal flexure due to a weak lower crust below Afar can elegantly account for the structural features of the WAM. Brittle crustal thickness controls what structures occur: a thinner brittle crust accommodates flexure internally, whereas increasing brittle thicknesses lead to faulting. Large escarpment faults develop early on, followed by late-stage antithetic faulting and marginal grabens. A thicker brittle crust also causes enhanced subsidence, and increased strength contrasts between lower crustal domains leads to more localized deformation. Basin-wide sedimentation causes enhanced subsidence, as well as longer activity along large synthetic (escarpment) faults. Finally, oblique extension clearly prevents the development of marginal grabens, which only form in near-orthogonal extension. These results support a tectonic scenario involving initial oblique extension due to Arabian plate motion, creating echelon synthetic escarpment faults along the WAM. After the Danakil Block started its independent rotation, near-orthogonal extension conditions were established, allowing (enhanced) marginal flexure, antithetic faulting and marginal graben formation along the older en echelon escarpment. Differences in extension obliquity may also explain the differences in structural architectures between the WAM and SAM. The characteristics of the WAM are typical of magma-rich passive margins, and the margin has great potential for studying continental break-up and (magma-rich) passive margin formation. © 2020 The Author(s)
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/170758
Appears in Collections: 气候变化与战略
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作者单位: Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Via la Pira 4, Florence, 50121, Italy; Institute of Geological Sciences, University of Bern, Baltzerstrasse 1+3, Bern, 3012, Switzerland; Consiglio Nazionale delle Ricerche, Istituto di Geoscienze e Georisorse, Via G. La Pira, 4, Florence, 50121, Italy; School of Ocean and Earth Science, University of Southampton, Southampton, SO14 3ZH, United Kingdom
Recommended Citation:
Zwaan F.,Corti G.,Keir D.,et al. Analogue modelling of marginal flexure in Afar, East Africa: Implications for passive margin formation[J]. Tectonophysics,2020-01-01,796