Passive-margin delta stratigraphy from source-to-sink numerical models: parametric studies and comparison with natural systems

2020 ◽  
Author(s):  
Brendan Simon ◽  
Cécile Robin ◽  
Delphine Rouby ◽  
Xiaoping Yuan ◽  
Laure Guerit ◽  
...  
Keyword(s):  
Landscape Evolution ◽  
Numerical Models ◽  
Input Parameter ◽  
Passive Margin ◽  
Geometrical Parameters ◽  
Natural Systems ◽  
Passive Margins ◽  
Source To Sink ◽  
Deposition Processes ◽  
The Impact

<p>One major and under-appreciated aspect of coupled erosion-deposition numerical modeling is the ranges of input parameter values used to simulate natural source to sink systems without considering their meaning in term of erosion, transport and deposition processes. Most of the time, numerical models are used as a semi-inversion tool based on a “best-fit” approach, especially in its marine part where it aims to reproduce well-constrained sedimentary architectures which are great recorders of landscape evolution through time.</p><p>In this study, we performed several simulations using a new numerical landscape evolution model that accounts for both erosion and deposition onshore, as well as sediment deposition in the marine domain (Yuan et al., 2019; COLORS project, funded by Total). In the marine domain, sediment dynamic is described by a diffusion equation and the diffusion or transport coefficient has been calibrated from natural delta geometries. This model is highly efficient and allows the separation of the different processes involved and exploration of various setups and parameters values in order to address a large variety of questions. Its efficiency also allows inverse simulations that are powerful to determine the best possible scenarios in terms of climatic or tectonic reconstructions, or to determine the evolution of several key parameters.</p><p>In order to evaluate the model reliability to reproduce realistic sedimentary geometries, we explore the impact of perturbations in climatic, eustatic or tectonic parameters of the model on the stratigraphic architecture of passive margins shelf-edge deltas and discuss its feedbacks with the erosion dynamic of the onshore domain. This sensitivity analysis also allowed us to define the most relevant geometrical parameters of observed or theoretical stratigraphic architectures that have to be include in the misfit function of the inversions and optimization scheme.</p><p><em>This study is part of the COLORS project, funded by Total.</em></p>

scholarly journals Melt volume at Atlantic volcanic rifted margins controlled by depth-dependent extension and mantle temperature

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Gang Lu ◽  
Ritske S. Huismans
Keyword(s):  
Numerical Models ◽  
Potential Temperature ◽  
Analytical Prediction ◽  
Natural Systems ◽  
Passive Margins ◽  
Margin Width ◽  
Rifted Margins ◽  
Mantle Potential Temperature ◽  
Mantle Temperature ◽  
Rifted Margin

AbstractBreakup volcanism along rifted passive margins is highly variable in time and space. The factors controlling magmatic activity during continental rifting and breakup are not resolved and controversial. Here we use numerical models to investigate melt generation at rifted margins with contrasting rifting styles corresponding to those observed in natural systems. Our results demonstrate a surprising correlation of enhanced magmatism with margin width. This relationship is explained by depth-dependent extension, during which the lithospheric mantle ruptures earlier than the crust, and is confirmed by a semi-analytical prediction of melt volume over margin width. The results presented here show that the effect of increased mantle temperature at wide volcanic margins is likely over-estimated, and demonstrate that the large volumes of magmatism at volcanic rifted margin can be explained by depth-dependent extension and very moderate excess mantle potential temperature in the order of 50–80 °C, significantly smaller than previously suggested.

scholarly journals Evaluation of Selected Metasurfaces’ Sensitivity to Planar Geometry Distortions

2019 ◽  
Vol 10 (1) ◽  
pp. 261
Author(s):  
Przemyslaw Lopato ◽  
Michal Herbko
Keyword(s):  
Numerical Models ◽  
Plane Deformation ◽  
Planar Geometry ◽  
Geometrical Parameters ◽  
Optical Frequency ◽  
Passive Devices ◽  
Planar Structures ◽  
Artificial Materials ◽  
Potential Applications ◽  
The Impact

In the last decade, the application of metamaterials has become a very interesting way of implementing passive devices in microwave, terahertz, and optical frequency ranges. Up until now, selective filters, absorbers, polarizers, and lenses have been designed and constructed using these artificial materials, simultaneously showing the possibility for many other potential applications. Because of the simplified fabrication process, in particular, planar structures called metasurfaces (MS), are developing very fast. In the literature, there are many studies on the properties of various metasurfaces, but there are a lack of papers related to the analysis of the impact of structure deformations on their properties. In this paper, three commonly utilized structures of metasurfaces were designed for the same resonant frequency and on the same substrate. The numerical models were built and verified using the measurements of fabricated structures. During the experiment, the geometrical parameters of the metasurface cells were swept and a mechanical in-plane deformation in orthogonal directions was applied to the examined structures. Finally, sensitivity to the geometry distortions of the analyzed structures was evaluated and discussed.

scholarly journals Impact of upper mantle convection on lithosphere hyperextension and subsequent horizontally forced subduction initiation

Solid Earth ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 2327-2357
Author(s):  
Lorenzo G. Candioti ◽  
Stefan M. Schmalholz ◽  
Thibault Duretz
Keyword(s):  
Upper Mantle ◽  
Mantle Convection ◽  
Driving Forces ◽  
Numerical Models ◽  
Passive Margin ◽  
Continuous Simulation ◽  
Subduction Initiation ◽  
Lithosphere Dynamics ◽  
The Impact

Abstract. Many plate tectonic processes, such as subduction initiation, are embedded in long-term (>100 Myr) geodynamic cycles often involving subsequent phases of extension, cooling without plate deformation and convergence. However, the impact of upper mantle convection on lithosphere dynamics during such long-term cycles is still poorly understood. We have designed two-dimensional upper-mantle-scale (down to a depth of 660 km) thermo-mechanical numerical models of coupled lithosphere–mantle deformation. We consider visco–elasto–plastic deformation including a combination of diffusion, dislocation and Peierls creep law mechanisms. Mantle densities are calculated from petrological phase diagrams (Perple_X) for a Hawaiian pyrolite. Our models exhibit realistic Rayleigh numbers between 106 and 107, and the model temperature, density and viscosity structures agree with geological and geophysical data and observations. We tested the impact of the viscosity structure in the asthenosphere on upper mantle convection and lithosphere dynamics. We also compare models in which mantle convection is explicitly modelled with models in which convection is parameterized by Nusselt number scaling of the mantle thermal conductivity. Further, we quantified the plate driving forces necessary for subduction initiation in 2D thermo-mechanical models of coupled lithosphere–mantle deformation. Our model generates a 120 Myr long geodynamic cycle of subsequent extension (30 Myr), cooling (70 Myr) and convergence (20 Myr) coupled to upper mantle convection in a single and continuous simulation. Fundamental features such as the formation of hyperextended margins, upper mantle convective flow and subduction initiation are captured by the simulations presented here. Compared to a strong asthenosphere, a weak asthenosphere leads to the following differences: smaller value of plate driving forces necessary for subduction initiation (15 TN m−1 instead of 22 TN m−1) and locally larger suction forces. The latter assists in establishing single-slab subduction rather than double-slab subduction. Subduction initiation is horizontally forced, occurs at the transition from the exhumed mantle to the hyperextended passive margin and is caused by thermal softening. Spontaneous subduction initiation due to negative buoyancy of the 400 km wide, cooled, exhumed mantle is not observed after 100 Myr in model history. Our models indicate that long-term lithosphere dynamics can be strongly impacted by sub-lithosphere dynamics. The first-order processes in the simulated geodynamic cycle are applicable to orogenies that resulted from the opening and closure of embryonic oceans bounded by magma-poor hyperextended rifted margins, which might have been the case for the Alpine orogeny.

Subduction channel vs. orogenic wedge model: numerical simulations, impact of serpentinites and application to the Alps

2020 ◽  
Author(s):  
Lorenzo G. Candioti ◽  
Stefan M. Schmalholz ◽  
Thibault Duretz
Keyword(s):  
Channel Model ◽  
Thermal Relaxation ◽  
Passive Margin ◽  
Crustal Material ◽  
Subduction Channel ◽  
Passive Margins ◽  
Coupled Equations ◽  
Orogenic Wedge ◽  
Simulation Results ◽  
The Impact

<p>In this study, we use a state-of-the-art 2D numerical algorithm solving the standard thermo-mechanically coupled equations of continuum mechanics for slow flowing viscoelastoplastic material to model the evolution of rifting, thermal relaxation and convergence-to-collision of Alpine-type orogens in three stages. (1) A ca. 360 km wide basin that is floored by exhumed mantle and bounded by two conjugate magma-poor hyper-extended passive margins is generated during a 50 Myrs rifting period. An absolute extension velocity of 1 cm/yr is applied. (2) The passive margin system is thermally equilibrated during a subsequent cooling period of 60 Myrs without significant deformation in the lithosphere (no extension velocity). At this stage, we parameterise a serpentinization front on top of the exhumed mantle by replacing the dry peridotitic mantle by serpentinized mantle in one series of simulations. The thermally equilibrated system is used as a self-consistently generated initial configuration for the subsequent period of convergence lasting for 70 Myrs applying an absolute convergence velocity of 1.5 cm/yr. Values for the duration of deformation periods and for deformation velocities are chosen to allow for comparison between simulation results and petrological data from the Central and Western Alps. Density of all materials is either precomputed for characteristic bulk rock compositions and read in from precomputed thermodynamic look-up tables (Perple_X), or calculated during run time via a linearized equation of state (EOS).</p><p> </p><p>We quantify (1) the impact of a serpentinization front of the exhumed mantle on the subduction dynamics by increasing systematically the strength of the serpentinites, (2) the peak pressure and temperature conditions of subducted crustal material from the passive margins of the overriding and subducting plate by tracking pressure (P)-temperature (T)-time (t)-depth (z) paths of selected particles and (3) the driving forces of the system. Last, (4) the impact of metamorphic phase transitions is investigated by parameterising densification of crustal material. We compare the results of simulations in which density is computed as a simple linearized EOS to results of simulations in which density is a more realistic function of P and T using precomputed thermodynamic look-up tables.</p><p> </p><p>We discuss geometric similarities between the simulation results and 2D geodynamic reconstructions from field data, quantify the P-T-t-z-history of selected particles and compare it to P-T-t data obtained from natural rocks. First results indicate that the strength of the serpentinites controls whether the deformation within the orogenic core is driven by buoyancy forces (subduction channel model) or by far-field tectonic forces (orogenic wedge model). There is a transition from subduction channel to orogenic wedge model from low to intermediate strength of the serpentinites.</p>

scholarly journals Experiment and Simulation of Erosion Mechanism and Deformation Characteristics in Al6061-T6 beam due to Rhomboid Particle Impacts

2021 ◽  
Author(s):  
MingChao Du ◽  
Zengliang Li ◽  
Xiangwei Dong ◽  
Chunyong Fan ◽  
Jiaqi Che ◽  
...  
Keyword(s):  
Cantilever Beam ◽  
High Speed ◽  
Imaging System ◽  
Numerical Models ◽  
Geometrical Parameters ◽  
Deformation Characteristics ◽  
Erosion Mechanism ◽  
Impact Position ◽  
Shaped Particle ◽  
The Impact

Abstract The erosion mechanism and deformation characteristics of rhomboid-shaped particle impacting metal beam are studied. Physical experiments of rhomboid-shaped particle impacting cantilever beam and fixed-fixed beam are carried out respectively. The erosion behavior of particles and deformation characteristics of beam are captured by high-speed imaging system. Meanwhile, the numerical models of rhomboid-shaped particle impacting beam, based on FEM-SPH coupled method, are established. The effects of the geometrical parameters of the beam, the incident conditions of particle and the impact position on the elastic-plastic deformation of beam and rebound behavior of particles are further analyzed. The results show: (1) The width of cantilever beam affects its maximum deflection and deformation; (2) The threshold value of breakdown velocity is controlled by the substrate size; (3) The increment of internal energy is basically independent of the impact position; (4) The deflection value at impact position of beam is maximized under the critical impact condition.

Segmentation and structural style evolution during continental breakup: observations from the Northern Bay of Biscay passive margin (offshore France)

2020 ◽  
Author(s):  
Julie Tugend ◽  
Emmanuel Masini ◽  
Sylvie Leroy ◽  
Laurent Jolivet
Keyword(s):  
North Atlantic Ocean ◽  
Passive Margin ◽  
Distal Margin ◽  
Bay Of Biscay ◽  
Progressive Change ◽  
Continental Breakup ◽  
Passive Margins ◽  
The North ◽  
Structural Style ◽  
The Impact

<p>The extension and thinning of the continental lithosphere during rifting may eventually lead to continental breakup. Related mechanisms are recorded within the Continent-Ocean Transitions (COT) of distal passive margins, showing different, often complex, tectono-magmatic interactions as revealed by the variability of basement architectures imaged by seismic data. Different extensional structures are interpreted in the COT, including high-angle or low-angle extensional faults dipping either oceanward or continentward. This variability appears mainly controlled by the initial rheological stratification of the lithosphere and its evolution during rifting. As a result, the relative influence between lower crustal ductility, crustal embrittlement, and serpentinization of the underlying mantle are the main parameters considered to explain the structural variability observed in the COT.</p><p>In this contribution, we document the tectonic evolution of the northern Bay of Biscay passive margin and show the impact of passive margin segmentation in controlling along strike changes in structural style during rifting and continental breakup. The Bay of Biscay is a V-shaped oceanic basin, which opened during the northward propagation of the North Atlantic Ocean. Its bordering magma-poor passive margins formed subsequently to a Late Jurassic to Early Cretaceous oblique rifting and Aptian-Albian oceanic spreading onset. A large number of studies already focused on this margin revealing a first-order along strike segmentation, but the structures accommodating the passage from one to the other segment remained poorly constrained.</p><p>We used a series of reflection seismic sections and complementary marine data sets such as dredges and drilling results from the Deep Sea Drilling Project to map the structural pattern and stratigraphic evolution related to this segment transition. Our seismic interpretations and mapping of the main rift structures define a relatively loose segment transition marked by a progressive change in structural style expressed differently between the COT and the rest of the passive margin. The differences observed between the proximal and distal parts of the margin can be explained by an evolution of the nature and depth of the main fault décollement level; crustal embrittlement and serpentinization becoming important controlling parameters oceanward. However, the progressive change in structural style observed in the distal margin from west to east from oceanward dipping to mainly continentward dipping faults is more likely to be related a different accommodation of extensional deformation across the transfer zone. This segmentation occurs near major pre-existing structures identified further continentward, suggesting a key role of inheritance.</p><p>Results of this work reveal the impact of margin segmentation in controlling changes in structural style at the end of rifting. If this soft transfer zones do not seem to be observed as far as the first oceanic crust, further work is required to determine how far it can control different interplay between tectonic and magmatic processes further oceanward in the COT.</p>

scholarly journals eSCAPE: Regional to Global Scale Landscape Evolution Model v2.0

2019 ◽  
Vol 12 (9) ◽  
pp. 4165-4184 ◽  
Author(s):  
Tristan Salles
Keyword(s):  
Landscape Evolution ◽  
Iterative Algorithms ◽  
Global Scale ◽  
Evolution Model ◽  
Mathematical Representation ◽  
Stream Power ◽  
Geological Time ◽  
Surface Evolution ◽  
Source To Sink ◽  
Deposition Processes

Abstract. The eSCAPE model is a Python-based landscape evolution model that simulates over geological time (1) the dynamics of the landscape, (2) the transport of sediment from source to sink, and (3) continental and marine sedimentary basin formation under different climatic and tectonic conditions. The eSCAPE model is open-source, cross-platform, distributed under the GPLv3 licence, and available on GitHub (http://escape.readthedocs.io, last access: 23 September 2019). Simulated processes rely on a simplified mathematical representation of landscape processes – the stream power and creep laws – to compute Earth's surface evolution by rivers and hillslope transport. The main difference with previous models is in the underlying numerical formulation of the mathematical equations. The approach is based on a series of implicit iterative algorithms defined in matrix form to calculate both drainage area from multiple flow directions and erosion–deposition processes. The eSCAPE model relies on the PETSc parallel library to solve these matrix systems. Along with the description of the algorithms, examples are provided to illustrate the model current capabilities and limitations. It is the first landscape evolution model able to simulate processes at the global scale and is primarily designed to address problems on large unstructured grids (several million nodes).

Geomorphologic Evolution of Northern Tibetan Plateau in the Quaternary: Tectonic and Climatic Controls

2021 ◽  
pp. 1-56
Author(s):  
Weijing Liu ◽  
Keyu Liu ◽  
Jianliang Liu ◽  
Yifan Zhang
Keyword(s):  
Climate Changes ◽  
Landscape Evolution ◽  
Qaidam Basin ◽  
Tectonic Uplift ◽  
Tibet Plateau ◽  
Sedimentary Evolution ◽  
Source To Sink ◽  
Deposition Thickness ◽  
The Impact ◽  
Qinghai Tibet Plateau

Situated in the northwestern Qinghai-Tibet Plateau, the Qaidam Basin is the largest Cenozoic terrestrial intermountain basin in the world. It is an ideal place for understanding the coupling control of tectonics and climate on sedimentary evolution. Although numerous studies on the Quaternary sedimentary evolution of the Qaidam Basin have been done, most of which are of local, conceptual and qualitative in nature. In this study, we investigated the entire Qaidam Basin and its surrounding mountains quantitatively as a single entity to probe the Quaternary evolution of the basin-range system in the northern Qinghai-Tibet Plateau. We used a Basin and Landscape Dynamics (Badlands) modeling algorithm that is capable of modeling landscape evolution by simulating erosion, sediment transport and deposition in a source-to-sink context by considering climate changes and tectonic uplift. We have simulated the evolution of the Qaidam Basin and its surrounding mountains since 2.5 Ma quantitatively. Both tectonic uplift and climate changes appear to have a direct impact on the denudation and deposition rates, but the impact varies through time. The deposition in the Qaidam Basin was mainly affected by tectonic movement during the period of 2.5 Ma to 0.6 Ma, reaching a maximum deposition thickness of 2130 m at the end of 0.6 Ma, but was prevailed by climate after 0.6 Ma during the last four glacials-interglacials, reaching a maximum deposition thickness of 3200 m. The Qilian Mountains and the Kunlun Mountains contributed the bulk sediments to the Qaidam Basin around 35% and 40%, respectively. The Altun Mountains made a significant contribution to the sediments in the Qaidam Basin during the early Quaternary from 2.5 Ma to 2.4 Ma due to a high denudation rate. The findings provide new insights for analyzing geomorphic and landscape evolution as well as source-to-sink systems in the Northern Qinghai-Tibet Plateau.

scholarly journals Overprinting translational domains in passive margin salt basins: insights from analogue modelling

Solid Earth ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 1283-1300 ◽  
Author(s):  
Zhiyuan Ge ◽  
Matthias Rosenau ◽  
Michael Warsitzka ◽  
Rob L. Gawthorpe
Keyword(s):  
Sedimentation Rate ◽  
Early Stage ◽  
Structural Evolution ◽  
Passive Margin ◽  
Image Correlation ◽  
Natural Systems ◽  
Passive Margins ◽  
Analogue Modelling ◽  
Transient Feature ◽  
Cover Thickness

Abstract. Current models of gravitational tectonics on the structural styles of salt-influenced passive margins typically depict domains of upslope extension and corresponding downslope contraction separated by a mid-slope domain of translation that is rather undeformed. However, an undeformed translational domain is rarely observed in natural systems as extensional and contractional structures tend to interfere in the mid-slope area. In this study, we use sandbox analogue modelling analysed by digital image correlation (DIC) to investigate some of the factors that control the structural evolution of translational domains. As in nature, experimental deformation is driven by slowly increasing gravitational forces associated with continuous basal tilting. The results show that a translational domain persists throughout the basin evolution when the pre-kinematic layer is evenly distributed. However, a thin (1 mm in the experiment, 100 m in nature) pre-kinematic layer can render the translational domain relatively narrow compared to settings with a thicker (5 mm) pre-kinematic layer. In contrast, early differential sedimentary loading in the mid-slope area creates minibasins separated by salt diapirs overprinting the translational domain. Similarly, very low sedimentation rate (1 mm per day in the experiment, < 17 m Ma−1 in nature) in the early stage of the experiment results in a translational domain quickly overprinted by downslope migration of the extensional domain and upslope migration of the contractional domain. Our study suggests that the architecture of passive margin salt basins is closely linked to the pre- and syn-kinematic cover thickness. The translational domain, as an undeformed region in the supra-salt cover, is a transient feature and overprinted in passive margins with either low sedimentation rate or a heterogeneous sedimentation pattern.

scholarly journals Lateral propagation–induced subduction initiation at passive continental margins controlled by preexisting lithospheric weakness

2020 ◽  
Vol 6 (10) ◽  
pp. eaaz1048 ◽  
Author(s):  
Xin Zhou ◽  
Zhong-Hai Li ◽  
Taras V. Gerya ◽  
Robert J. Stern
Keyword(s):  
Subduction Zones ◽  
Plate Tectonics ◽  
Numerical Models ◽  
Three Dimensional ◽  
Passive Margin ◽  
Continental Margins ◽  
Subduction Initiation ◽  
Passive Margins ◽  
The North ◽  
Lateral Propagation

Understanding the conditions for forming new subduction zones at passive continental margins is important for understanding plate tectonics and the Wilson cycle. Previous models of subduction initiation (SI) at passive margins generally ignore effects due to the lateral transition from oceanic to continental lithosphere. Here, we use three-dimensional numerical models to study the possibility of propagating convergent plate margins from preexisting intraoceanic subduction zones along passive margins [subduction propagation (SP)]. Three possible regimes are achieved: (i) subducting slab tearing along a STEP fault, (ii) lateral propagation–induced SI at passive margin, and (iii) aborted SI with slab break-off. Passive margin SP requires a significant preexisting lithospheric weakness and a strong slab pull from neighboring subduction zones. The Atlantic passive margin to the north of Lesser Antilles could experience SP if it has a notable lithospheric weakness. In contrast, the Scotia subduction zone in the Southern Atlantic will most likely not propagate laterally.

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