气候变化领域集成服务门户(CCPortal): Analogue modelling of marginal flexure in Afar, East Africa: Implications for passive margin formation

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DOI	10.1016/j.tecto.2020.228595
	Analogue modelling of marginal flexure in Afar, East Africa: Implications for passive margin formation
	Zwaan F.; Corti G.; Keir D.; Sani F.
发表日期	2020
ISSN	00401951
卷号	796
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)
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
语种	英语
来源期刊	Tectonophysics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/207925
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
推荐引用方式 GB/T 7714	Zwaan F.,Corti G.,Keir D.,et al. Analogue modelling of marginal flexure in Afar, East Africa: Implications for passive margin formation[J],2020,796.
APA	Zwaan F.,Corti G.,Keir D.,&Sani F..(2020).Analogue modelling of marginal flexure in Afar, East Africa: Implications for passive margin formation.Tectonophysics,796.
MLA	Zwaan F.,et al."Analogue modelling of marginal flexure in Afar, East Africa: Implications for passive margin formation".Tectonophysics 796(2020).