Impact of crustal rheology and inherited mechanical weaknesses on early continental rifting and initial evolution of double graben structural configurations: Insights from 2D numerical models

Oliveira, Magda Estrela; Gomes, Afonso; Rosas, Filipe; Duarte, João C.; França, George Sand; Almeida, Jaime; Fuck, Reinhardt A.

doi:10.1016/j.tecto.2022.229281

Cited by 8 publications

(8 citation statements)

References 51 publications

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“…In particular, the asymmetric topography observed in model Q1 recall the topography recorded in correspondence of the Conrad Deep in the northern part of the Red Sea, with similar maximum heights of approximately 1,500 m on the eastern side and between 500 and 1,000 m on the western side (Bosworth, 2015; Ehrhardt & Hübscher, 2015). Therefore, the asymmetric evolution of our models is in agreement with both previous numerical models (e.g., Chenin & Beaumont, 2013; Oliveira et al., 2022; Peron‐Pinvidic et al., 2022; Theunissen & Huismans, 2022) and natural observation (e.g., Bosworth, 2015; Ehrhardt & Hübscher, 2015; Youssef, 2015) of continental rifting. Since weakening have been proven to have an impact on the evolution of diverge tectonic settings (e.g., Choi et al., 2013; Lavier et al., 1999, 2000), we made a test changing weakening parameters in order to verify if they can affect significantly the evolution of our system (model R2).…”

Section: Discussionsupporting

confidence: 91%

Rifting Venus: Insights From Numerical Modeling

et al. 2023

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Venus is a terrestrial planet with dimensions similar to the Earth, but a vastly different geodynamic evolution, with recent studies debating the occurrence and extent of tectonic‐like processes happening on the planet. The precious direct data that we have for Venus is very little, and there are only few numerical modeling studies concerning lithospheric‐scale processes. However, the use of numerical models has proven crucial for our understanding of large‐scale geodynamic processes of the Earth. Therefore, here we adapt 2D thermomechanical numerical models of rifting on Earth to Venus to study how the observed rifting structures on the Venusian surface could have been formed. More specifically, we aim to investigate how rifting evolves under the Venusian surface conditions and the proposed lithospheric structure. Our results show that a strong crustal rheology such as diabase is needed to localize strain and to develop a rift under the high surface temperature and pressure of Venus. The evolution of the rift formation is predominantly controlled by the crustal thickness, with a 25 km‐thick diabase crust required to produce mantle upwelling and melting. The surface topography produced by our models fits well with the topography profiles of the Ganis and Devana Chasmata for different crustal thicknesses. We therefore speculate that the difference in these rift features on Venus could be due to different crustal thicknesses. Based on the estimated heat flux of Venus, our models indicate that a crust with a global average lower than 35 km is the most likely crustal thickness on Venus.

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Section: Discussionsupporting

confidence: 91%

Rifting Venus: Insights From Numerical Modeling

et al. 2023

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“…The development of such double shear zones and associated double graben structures has been observed in both lithospheric-scale analog models (e.g., Brun & Beslier, 1996;Michon & Merle, 2000Nestola et al, 2015), as well as in crustal-scale brittle-viscous models, where instead of a seed the edge of a base plate (VD) represents a fault in the upper lithospheric mantle (e.g., Allemand et al, 1989;Michon & Merle, 2000Zwaan et al, 2019Zwaan et al, , 2021Zwaan, Chenin, et al, 2022). Moreover, they are also observed in numerical modeling studies (Chenin et al, 2018(Chenin et al, , 2020Dyksterhuis et al, 2007;Oliveira et al, 2022). In the case of a symmetric rift structure, two of these shear zones form simultaneously on both sides of the seed, causing the development of two equally sized grabens in the upper crustal layer, with a relatively undeformed "H-block" (i.e., "hanging wall block," Lavier & Manatschal, 2006;Péron-Pinvidic & Manatschal, 2010) in between (Figures 12b and 12c).…”

Section: Symmetric Versus Asymmetric Rift Developmentmentioning

confidence: 77%

“…The absence of deformation in the form of faulting in the upper crustal layer along the central axis of Model A without a seed, highlights that such a seed is required to localize a rift structure in this model set-up (compare Model A with Models B-D, Figures 3-11a, 11c). The need for a seed or weakness to localize deformation in brittle-viscous set-ups has been shown by various previous analog and numerical modelers (e.g., Oliveira et al, 2022;Zwaan et al, 2019), and is linked to the decoupling effect of the weak viscous layer representing the lower crust. This decoupling isolates the competent brittle layers in the model lithosphere, and deformation will simply focus along the sidewalls, which form the weakest part of the model, whereas the brittle layers simulating the upper crust and upper lithospheric mantle remain stationary and undeformed.…”

Section: Localization Of Faulting: Effects Of Seed and Couplingmentioning

confidence: 99%

Analog Models of Lithospheric‐Scale Rifting Monitored in an X‐Ray CT Scanner

Zwaan

Schreurs

2023

Tectonics

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Rifting and continental break‐up are fundamental tectonic processes, the understanding of which is of prime importance. However, the vast temporal and spatial scales involved pose major limitations to researchers. Analog tectonic modeling represents a great means to mitigate these limitations, but studying the complex internal deformation of lithospheric‐scale models remains a challenge. We therefore present a novel method for lithospheric‐scale rifting models that are uniquely monitored in an X‐ray CT scanner, which combined with digital image correlation (DIC) techniques, provides unparalleled insights into model deformation. Our first models illustrate how the degree of coupling between competent lithospheric layers, which are separated by a weak lower crustal layer, strongly impacts rift system development. Low coupling isolates the upper crust from the upper lithospheric mantle layer below, preventing an efficient transfer of deformation between both layers. By contrast, fast rifting increases coupling, so that deformation in the mantle is efficiently transferred to the upper crust, inducing either a symmetric or asymmetric (double) rift system. Furthermore, oblique divergence may lead to en echelon graben arrangements and delayed exhumation of the lower crustal layer. The successful application of our novel modeling approach, yielding these first‐order insights, provides a clear incentive to continue running lithospheric‐scale rifting models, and to apply advanced monitoring techniques to extract as much information from models as possible. There is indeed a broad range of opportunities for follow‐up studies within (and beyond) the field of rift tectonics.

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“…These magmas can accommodate extension via dyke intrusion and, depending on their distribution in space and time, may alter the thermo‐mechanical structure of the crust (e.g., Buck, 2006; Daniels et al., 2014; Lavecchia et al., 2016; Muluneh et al., 2020). Determining how intruded melts accumulate during rift development is therefore crucial for understanding how the rheology and density structure of the crust evolves with progressive rifting, which in turn has a strong influence on how the crust responds to far‐field extensional stresses during non‐magmatic and magmatic rifting regimes (e.g., Bialas et al., 2010; Oliveira et al., 2022; Tetreault & Buiter, 2018).…”

Section: Introductionmentioning

confidence: 99%