Surface processes control on orogenic evolution: inferences from 3D coupled numerical models and observations from the India-Eurasia collision zone

2021 ◽  
Author(s):  
Luuk van Agtmaal ◽  
Attila Balazs ◽  
Dave May ◽  
Taras Gerya
Keyword(s):  
Numerical Models ◽  
Surface Processes ◽  
Climatic Forcing ◽  
Plate Convergence ◽  
Thermal Fields ◽  
Denudation Rates ◽  
Collision Zone ◽  
Sediment Transportation ◽  
Modelling Techniques ◽  
Evolution Modeling

<p>The inherent links between tectonics, surface processes and climatic variations have long since been recognised as the main drivers for the evolution of orogens. Oceanic and continental subduction and collision processes lead to distinct topographic signals. Simultaneously, different climatic forcing factors and denudation rates substantially modify the style of deformation leading to different stress and thermal fields, strain localisation and even deep mantle evolution. An ideal area where the above-mentioned processes and their connections can be studied is the India-Eurasia collision zone.</p><p>Understanding the complex interplay between tectonics, erosion, sediment transportation and deposition requires the coupled application of thermo-mechanical and surface processes modelling techniques. To this aim, we used a 3D coupled numerical modelling approach. The influence of different plate convergence, erosion and sedimentation rates has been tested by the thermo-mechanical code I3ELVIS (Gerya and Yuen, 2007) coupled to the diffusion-advection based (FDSPM) surface processes model.</p><p>We show preliminary results to demonstrate  that the diffusion-advection erosion implementation has significant effects on local and regional mass redistribution and topographic evolution within narrow, curved, high orogens such as the Himalayas and their syntaxes, where erosion is a dominant forcing factor. We also discuss possible implications from different erosion/sedimentation implementations such as DAC (Ueda et al., 2015; Goren et al., 2014) in combination with the reference thermo-mechanical model to analyse changes in orogenic development as a consequence of different erosional processes in more detail.</p><p>References:</p><p>Gerya, T. V., & Yuen, D. A. (2007). Robust characteristics method for modelling multiphase visco-elasto-plastic thermo-mechanical problems. Physics of the Earth and Planetary Interiors, 163(1-4), 83-105. <br>Ueda, K., Willett, S. D., Gerya, T., & Ruh, J. (2015). Geomorphological–thermo-mechanical modeling: Application to orogenic wedge dynamics. Tectonophysics, 659, 12-30.<br>Goren, L., Willett, S. D., Herman, F., & Braun, J. (2014). Coupled numerical–analytical approach to landscape evolution modeling. Earth Surface Processes and Landforms, 39(4), 522-545.</p>

Geological signatures of slab shear-off during ongoing India-Asia convergence

2021 ◽  
Author(s):  
Abdul Qayyum ◽  
Nalan Lom ◽  
Eldert L Advokaat ◽  
Wim Spakman ◽  
Douwe J.J van Hinsbergen
Keyword(s):  
Numerical Models ◽  
Leading Edge ◽  
Plate Motion ◽  
Indian Plate ◽  
Mantle Structure ◽  
Continental Lithosphere ◽  
Common View ◽  
Plate Convergence ◽  
Collision Zone ◽  
The Himalaya

<p>Much of our understanding of the dynamics of slab break-off and its geological signatures rely on numerical models with a simplified set-up, in which slab break-off follows arrival of a continent in a mantle-stationary trench, the subsequent arrest of plate convergence, and after a delay time of 10 Ma or more, slab break off under the influence of slab pull. However, geological reconstructions show that plate tectonic reality deviates from this setup: post-collisional convergence is common, trenches are generally not stationary relative to mantle, neither before nor after collision, and there are many examples in which the mantle structure below collision zones is characterized by more, or fewer slabs than collisions.</p><p>A key example of the former is the India-Asia collision zone, where the mantle below India hosts two major, despite the common view of a single collision. Kinematic reconstructions reveal that post-collisional convergence amounted 1000s of kms, and was associated with ~1000 km of trench/collision zone advance. Collision between India-Asia collision zone may provide a good case study to determine the result of post-collisional convergence and absolute lower and upper plate motion on mantle structure, and to evaluate to what extent commonly assumed diagnostic geological phenomena of slab break-off apply.</p><p>In addition to the previously identified major India, Himalaya, and Burma slabs, we here map smaller slabs below Afghanistan and the Himalaya that reveal the latest phases of break-off. We show that west-dipping and east-dipping slabs west and east of India, respectively, are dragged northward parallel to the slab, slabs subducting north of India are overturned, and that the shallowest slab fragments are found in the location where the horizontally underthrust Indian lithosphere below Tibet is narrowest. Our results confirm that northward Indian absolute plate motion continued during two episodes of break-off of large (>1000 km wide) slabs, and decoupling of several smaller fragments. These slabs are currently found south of the present day trench locations. The slabs are located even farther south (>1000 km) of the leading edge of the Indian continental lithosphere, currently underthrust below Tibet, from which the slabs detached, signalling ongoing absolute Indian plate motion. We conclude that the multiple slab break-off events in this setting of ongoing plate convergence and trench advance is better explained by shearing off of slabs from the downgoing plate, possibly at a depth corresponding to the base of the Indian continental lithosphere, are not (necessarily) related to the timing of collision. A recently proposed, detailed diachronous record of deformation, uplift, and oroclinal bending in the Himalaya that was liked to slab break-off fits well with our kinematically reconstructed timing of the last slab shear-off, and may provide an important reference geological record for this process. We find that the commonly applied conceptual geological signatures of slab break-off do not apply to the India-Asia collision zone, or to similar settings and histories such as the Arabia-Eurasia collision zone. Our study provides more realistic boundary conditions for future numerical models that aim to assess the dynamics of subduction termination and its geological signatures.</p>

Millennial scale variability of denudation rates for the last 15 kyr inferred from the detrital 10Be record of Lake Stappitz in the Hohe Tauern massif, Austrian Alps

The Holocene ◽  
2017 ◽  
Vol 27 (12) ◽  
pp. 1914-1927 ◽  
Author(s):  
Reto Grischott ◽  
Florian Kober ◽  
Maarten Lupker ◽  
Juergen M Reitner ◽  
Ruth Drescher-Schneider ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Anthropogenic Impacts ◽  
Sediment Cores ◽  
Tight Coupling ◽  
Climatic Forcing ◽  
Erosion Rates ◽  
Austrian Alps ◽  
Denudation Rates ◽  
Time Period ◽  
Flooding Events

Reconstructing paleo-denudation rates over Holocene timescales in an Alpine catchment provides a unique opportunity to isolate the climatic forcing of denudation from other tectonic or anthropogenic effects. Cosmogenic 10Be on two sediment cores from Lake Stappitz (Austrian Alps) were measured yielding a 15-kyr-long catchment-averaged denudation record of the upstream Seebach Valley. The persistence of a lake at the outlet of the valley fixed the baselevel, and the high mean elevation minimizes anthropogenic impacts. The 10Be record indicates a decrease in the proportion of paraglacial sediments from 15 to 7 kyr cal. BP after which the 10Be concentrations are considered to reflect hillslope erosion and thus can be converted to denudation rates. These ones significantly fluctuated over this time period: lower hillslope erosion rates of ca. 0.4 mm/year dated between 5 and 7 kyr cal. BP correlate with a stable climate, sparse flooding events and elevated temperatures that favoured the widespread growth of stabilizing soils and vegetation. Higher hillslope erosion rates of ca. 0.8 mm/year over the last ~4 kyr correlate with a variable, cooler climate where frequent flooding events enhance denudation of less protected hillslopes. Overall, our results suggest a tight coupling of climate and hillslope erosion in alpine landscapes as it has been observed in other parts of the Alps.

Stratigraphy and sediment signal transmission in a flexural foreland basin dynamically linked to an uplifting range

2020 ◽  
Author(s):  
Laure Guerit ◽  
Delphine Rouby ◽  
Cécile Robin ◽  
François Guillocheau ◽  
Brendan Simon ◽  
...  
Keyword(s):  
Numerical Models ◽  
Accumulation Rate ◽  
Foreland Basin ◽  
Surface Processes ◽  
Precipitation Rate ◽  
Foreland Basins ◽  
Uplift Rate ◽  
Mountain Belts ◽  
Aquitaine Basin ◽  
Topographic Evolution

<p>Foreland basins that develop at the foot of collisional mountain belts accumulate sediments eroded from the ranges. They thus represent valuable archives of the evolution of orogenic systems through time. A few numerical models have investigated the infilling of foreland basins during the growth of an orogenic range and they provide conceptual frameworks for foreland stratigraphy. However, surface processes (erosion, sediment transport and deposition) are often quite basic in these models, and in the last decade, progress has been made in the description of surface processes and its implementation in numerical models. Recently, we developed a landscape evolution model able to describe the evolution of an eroding source coupled to a flexural sedimentary basin (Yuan et al, 2019, JGR; Guerit et al, 2019, Geology). This model takes into account erosion and deposition at the same time, and it thus allows a full dynamical coupling of the range and its foreland. We take advantage of this efficient numerical model to take another look at the stratigraphic evolution of a foreland basin and at the transmission of sediment signal from source to sink. <br>We use the model to simulate the evolution of a flexural retro-foreland basin coupled to an uplifting range and subjected to temporal variations in uplift and precipitation rates. Such variations affect the topography of the range: a lower uplift rate or an higher precipitation lead to a lower range. As a result, because the accommodation space available in the foreland is purely flexural, a decrease in uplift rate or an increase in precipitation rate will be marked by an erosional surface in the foreland basin. On the contrary, an increase in uplift rate or a decrease in precipitation rate will be preserved in the stratigraphy. Interestingly, although the two scenarios induce a different sediment signal from the sources, they are both recorded in the foreland basin as a transient increase in accumulation rate. Such a signal alone can therefore not be used to decipher the type of perturbation that affected the source.<br>Finally, we discuss the evolution of a natural range and coupled foreland basin, the Pyrenees and the Aquitaine Basin. We show that the spatial pattern of sediment deposition in the Aquitaine Basin is very consistent with the topographic evolution of the Pyrenees. However, this topographic evolution is not consistent with the climatic and tectonic reconstruction in the area since the Eocene, opening discussions among others about local vs regional effects. This work is part of the COLORS project, funded by Total.</p>

Factors controlling the interaction between tectonics and surface processes in convergent orogens: insight from analogue and numerical models

2020 ◽  
Author(s):  
Riccardo Reitano ◽  
Claudio Faccenna ◽  
Francesca Funiciello ◽  
Fabio Corbi ◽  
Sean Willett
Keyword(s):  
Landscape Evolution ◽  
Numerical Models ◽  
Tectonic Setting ◽  
Laser Scanner ◽  
Sprinkler System ◽  
Surface Processes ◽  
Oblique View ◽  
Surface Uplift ◽  
Geomorphic Features ◽  
Set Up

<p>Convergent orogens are the best places on Earth for studying the interaction between surface processes and tectonics. They display the highest surface uplift rates and in turn are more likely affected by erosion. The balance between tectonics and erosion is responsible for many aspects in the evolution of a mountain belt. Despite the growth of analysis techniques, our understanding is still limited by the impossibility to observe these processes through their entire evolution. In particular, understanding how single parameters affect the system is necessary to unravel the nature of these multiple-interrelated processes.</p><p>Here we propose a new series of analogue models reproducing a simplified and scaled natural convergent orogenic system, to investigate the evolution of landscapes in which both tectonics and erosion/sedimentation are present. The growth of the orogenic wedge is driven by a rigid plate pushing the rear of the model. Deformed brittle granular material is a mixture of silica powder, glass microbeads and PVC powder. This mixture allows for the observation of both deforming structures and geomorphic features. Erosion is simulated by a water sprinkler system, providing a fine mist as precipitation which collects into simulated rivers, shaping the landscape. The model therefore allows observing the interaction between tectonics and surface processes. We analyze the model evolution monitoring oblique-view with cameras and top-view with a laser scanner. The latter is useful for measuring the mass balance between input fluxes (tectonics) and output fluxes (erosion) and in fulfilling a proper parametric study on the cause-effect relationship. The effect of different parameters on landscape evolution (e.g., precipitation rate, convergence velocity) is investigated systematically.</p><p>Our preliminary results analyze the relationship between single parameters and their effect on the models, allowing a proper definition of the role played in the landscape evolution. We also set up a benchmark with numerical models using DACI3ELVIS code in the same tectonic setting.</p>

scholarly journals A Comparison of Different Wave Modelling Techniques in An Open-Source Hydrodynamic Framework

2020 ◽  
Vol 8 (7) ◽  
pp. 526
Author(s):  
Weizhi Wang ◽  
Arun Kamath ◽  
Tobias Martin ◽  
Csaba Pákozdi ◽  
Hans Bihs
Keyword(s):  
Open Source ◽  
Stokes Equations ◽  
Numerical Models ◽  
Immersed Boundary ◽  
Wave Modelling ◽  
Advantages And Disadvantages ◽  
The Past ◽  
Modelling Techniques ◽  
Numerical Wave ◽  
Wave Models

Modern design for marine and coastal activities places increasing focus on numerical simulations. Several numerical wave models have been developed in the past few decades with various techniques and assumptions. Those numerical models have their own advantages and disadvantages. The proper choice of the most useful numerical tool depends on the understanding of the validity and limitations of each model. In the past years, REEF3D has been developed into an open-source hydrodynamic numerical toolbox that consists of several modules based on the Navier–Stokes equations, the shallow water equations and the fully nonlinear potential theory. All modules share a common numerical basis which consists of rectilinear grids with an immersed boundary method, high-order finite differences and high-performance computing capabilities. The numerical wave tank of REEF3D utilises a relaxation method to generate waves at the inlet and dissipate them at the numerical beach. In combination with the choice of the numerical grid and discretisation methods, high accuracy and stability can be achieved for the calculation of free surface wave propagation and transformation. The comparison among those models provide an objective overview of the different wave modelling techniques in terms of their numerical performance as well as validity. The performance of the different modules is validated and compared using several benchmark cases. They range from simple propagations of regular waves to three-dimensional wave breaking over a changing bathymetry. The diversity of the test cases help with an educated choice of wave models for different scenarios.

scholarly journals Inishell 2.0: Semantically driven automatic GUI generation for scientific models

2020 ◽  
Author(s):  
Mathias Bavay ◽  
Michael Reisecker ◽  
Thomas Egger ◽  
Daniela Korhammer
Keyword(s):  
User Interface ◽  
Numerical Model ◽  
Learning Curve ◽  
Graphical User Interface ◽  
Numerical Models ◽  
Scientific Models ◽  
Surface Processes ◽  
Model Configuration ◽  
Specific Skill ◽  
Specific Project

Abstract. As numerical model developers, we have experienced first hand how most users struggle with the configuration of the models, leading to numerous support requests. Such issues are usually mitigated by offering a Graphical User Interface (GUI) that flattens the learning curve. This requires however a significant investment for the model developer as well as a specific skill set. Moreover, this does not fit with the daily duties of model developers. As a consequence, when a GUI has been created, usually within a specific project and often relying on an intern, the maintenance either constitutes a major burden or is not performed. This also tends to limit the evolution of the numerical models themselves, since the model developers try to avoid having to change the GUI. In this paper we describe an approach based on an XML description of the required numerical model configuration elements and a C++/Qt tool (Inishell) that creates a GUI based on this description on the fly. This makes maintenance of the GUI very simple and enables users to easily get an up-to-date GUI for configuring the numerical model. The first version of this tool was written almost ten years ago and showed that the concept works very well for our own surface processes models. A full rewrite offering a more modern interface and extended capabilities is presented in this paper.

scholarly journals Temporal evolution of surface processes inferred from cosmogenic nuclides in a slow erosion setting, insights from the Sera do Cipo range, Brazil

2020 ◽  
Author(s):  
Vincent Godard ◽  
André Salgado ◽  
Lionel Siame ◽  
Jules Fleury ◽  
Team Aster
Keyword(s):  
High Resolution ◽  
Frequency Component ◽  
Cosmogenic Nuclides ◽  
Surface Processes ◽  
Tectonic Activity ◽  
High Frequency Component ◽  
Strong Positive Correlation ◽  
Late Cenozoic ◽  
Denudation Rates ◽  
Small Catchments

<p>Understanding the degree of sensitivity of the Earth Surface to past climate changes is key to assess the strength of postulated links between weathering, denudation, rock uplift and climate. Numerous studies have investigated the response of surface processes to the evolution through time of temperature and precipitation, in various settings and over different time periods. In particular, an important question still actively debated concerns whether or not Late Cenozoic climate change had an effective impact on denudation rates. It is noteworthy that this Late Cenozoic climatic evolution is often described as a long-term cooling over several Ma. However, although it has been postulated to be an important control on this response, the impact of its orbitally-controlled high-frequency component has been less investigated.</p><p>Studies focusing on climate-denudation links have often been carried out in regions of high tectonic activity. Therefore, they encountered associated significant limitations, such as: (1) high denudation rates that reach the analytical limits of many measurement methods; (2) stochastic events introducing a high degree of variability in the denudation signal; and, (3) high rates of tectonic uplift that can limit the sensitivity to the low-frequency component of the climatic boundary condition. Less active tectonic settings with lower denudation rates may thus provide conditions allowing to focus specifically on the coupling between climate variations and surface processes. Additionally, approaches combining different cosmogenic nuclides have proven to be very effective to unravel changes in surface processes over several time scales.</p><p>We present a new cosmogenic nuclides dataset from the Sera do Cipo range in Minas Gerais, Brazil. The core of the range is made of resistant quarzite bedrock with a relief of 500 m with respect to the surrounding low lands, and reported denudation rates are <10 m/Ma. Streams sediments from small catchments near the summit divide, as well as clasts derived from massive quartz veins at hilltop locations, were sampled. Both <sup>10</sup>Be and <sup>26</sup>Al concentrations were measured in the collected samples, as in such slow denudation settings the ratio between the two nuclides is sensitive to changes in denudation rates through time. A high-resolution (1 m) Digital Elevation Models was also produced from tri-stereo Pléiades satellite images. This allows to compute high resolution metrics such as hilltop curvature at the sampling sites. Hilltop denudation rates display a strong positive correlation with curvature. <sup>26</sup>Al/<sup>10</sup>Be values significantly departing from the theoretical steady state denudation ratio are interpreted at hilltop sites as reflecting the fluctuation of denudation through time. Concerning the catchments samples, the determined ratio can also be impacted by the sediment transport history along hillslopes. Combining cosmogenic nuclides and high-resolution topographic datasets, the measured concentrations were inverted to constrain the variation of denudation over the last 2 Ma. We observe a significant change in the denudation regime at 1 Ma, with different kind of responses between ridges and small catchments across the landscape.</p>

An Application of Integrated Coastal Models on Protection of Sediment Deposition at Taichung Harbor

2009 ◽  
Author(s):  
Tai-Wen Hsu ◽  
Yu-Jie Jhu
Keyword(s):  
Wave Height ◽  
Numerical Models ◽  
Shoreline Change ◽  
Transport Parameters ◽  
Generalized Model ◽  
Shoreline Evolution ◽  
The North ◽  
Coastal Modeling ◽  
Sediment Transportation ◽  
Change System

The main objective of this paper is to study the protection of sediment siltation and shoreline evolution in Taichung harbor using two numerical models of SMC (Coastal Modeling System) and GENESIS (GENEralized model for SImulating Shoreline change System). Numerical results of wave height in the vicinity of groins were compared to validate the capability of SMC model. In addition, the transport parameters, K1 and K2 in GENESIS are calibrated. Some numerical cases were runned to simulate the nearshore hydrodynamics, the sediment transportation and siltation on the north area with siltation of Taichung harbor. In particular, a beach nourishment measure is proposed based on GENESIS simulations of shoreline change on southern eroded coast.

scholarly journals Numerical simulations of glacier evolution performed using flow-line models of varying complexity

2017 ◽  
Author(s):  
Antonija Rimac ◽  
Sharon van Geffen ◽  
Johannes Oerlemans
Keyword(s):  
Flow Line ◽  
Numerical Models ◽  
Natural Variability ◽  
Equilibrium Line Altitude ◽  
Climatic Forcing ◽  
Glacier Length ◽  
Glacier Flow ◽  
Bed Slope ◽  
Constant Slope ◽  
Periodic Changes

Abstract. The performance of two numerical models of different complexity, i.e., a Shallow Ice Approximation (SIA) and a Full-Stokes Model (FSM), is studied by analyzing glacier evolutions at various bed geometries and by applying different climatic forcings. Glacier bed geometry changes from a constant slope and a uniform width to a superimposed Gaussian bump or ice-fall on a constant slope and an exponentially varying width. Constant slopes of 0.1, 0.2 and 0.3 are chosen to study the evolution of a large, medium and small glacier, respectively. A specific mass balance serves as a climatic forcing. The steady state is reached 60, 30 and 10 years, respectively faster for large, medium and small glacier, when simulations are performed using SIA instead of FSM. Glaciers time response is studied by using step and periodic changes, and by imposing natural variability in the equilibrium-line altitude. Glacier length response time is up to 14 years longer when FSM is used compared to SIA. When periodic and natural variability are enforced, glaciers simulated using SIA lag in phase compared to the forcing up to 81.2° for glacier length and up to 56.5° for volume. Contrary to that, glaciers simulated with FSM show greater lag in phase compared to the forcing for glacier length and smaller lag for volume. The models differ in their treatment of glacier flow mechanics and differences in physical variables become apparent with increasing glacier bed slope and bed profile complexity.

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