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Topographic Evolution and Climate Aridification during Continental Collision: Insights from Computer Simulations.

Garcia-Castellanos D, Jiménez-Munt I - PLoS ONE (2015)

Bottom Line: For this purpose, we combine in a single computer program: 1) a thin-sheet viscous model of continental deformation; 2) a stream-power surface-transport approach; 3) flexural isostasy allowing for the formation of large sedimentary foreland basins; and 4) an orographic precipitation model that reproduces basic climatic effects such as continentality and rain shadow.At the continental scale, however, the overall distribution of topographic basins and ranges seems insensitive to climatic factors, despite these do have important, sometimes counterintuitive effects on the amount of sediments trapped within the continent.These complex climatic-drainage-tectonic interactions make the development of steady-state topography at the continental scale unlikely.

View Article: PubMed Central - PubMed

Affiliation: Group of Dynamics of the Lithosphere, Instituto de Ciencias de la Tierra Jaume Almera (ICTJA-CSIC), Barcelona, Spain.

ABSTRACT
How do the feedbacks between tectonics, sediment transport and climate work to shape the topographic evolution of the Earth? This question has been widely addressed via numerical models constrained with thermochronological and geomorphological data at scales ranging from local to orogenic. Here we present a novel numerical model that aims at reproducing the interaction between these processes at the continental scale. For this purpose, we combine in a single computer program: 1) a thin-sheet viscous model of continental deformation; 2) a stream-power surface-transport approach; 3) flexural isostasy allowing for the formation of large sedimentary foreland basins; and 4) an orographic precipitation model that reproduces basic climatic effects such as continentality and rain shadow. We quantify the feedbacks between these processes in a synthetic scenario inspired by the India-Asia collision and the growth of the Tibetan Plateau. We identify a feedback between erosion and crustal thickening leading locally to a <50% increase in deformation rates in places where orographic precipitation is concentrated. This climatically-enhanced deformation takes place preferentially at the upwind flank of the growing plateau, specially at the corners of the indenter (syntaxes). We hypothesize that this may provide clues for better understanding the mechanisms underlying the intriguing tectonic aneurisms documented in the Himalayas. At the continental scale, however, the overall distribution of topographic basins and ranges seems insensitive to climatic factors, despite these do have important, sometimes counterintuitive effects on the amount of sediments trapped within the continent. The dry climatic conditions that naturally develop in the interior of the continent, for example, trigger large intra-continental sediment trapping at basins similar to the Tarim Basin because they determine its endorheic/exorheic drainage. These complex climatic-drainage-tectonic interactions make the development of steady-state topography at the continental scale unlikely.

No MeSH data available.


Related in: MedlinePlus

Parameterization.Dependence of the average tectonic strain localization (%) on orographic effects (incoming air humidity RH and mean wind velocity uw) and on the lithospheric elastic thickness. Strain localization is measured as the standard deviation of the accumulated vertical strain (dimensionless). Note that although the changes in this averaged are smaller than 1%, strain rates can locally be enhanced by 50% in areas of rapid erosion (Fig 7a). The reference setup is located with a circle.
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pone.0132252.g009: Parameterization.Dependence of the average tectonic strain localization (%) on orographic effects (incoming air humidity RH and mean wind velocity uw) and on the lithospheric elastic thickness. Strain localization is measured as the standard deviation of the accumulated vertical strain (dimensionless). Note that although the changes in this averaged are smaller than 1%, strain rates can locally be enhanced by 50% in areas of rapid erosion (Fig 7a). The reference setup is located with a circle.

Mentions: The results show that structural rheological contrasts such as the pre-existence of stronger lithospheric domains in the plate are more relevant in determining the localization of deformation, sedimentary basins, and topographic highs and lows, in front of climatic/erosional heterogeneities (note the similar overall topographic patterns predicted in all models in Fig 5). Orographically focalized erosion can locally modify by up to 50% the rates at which the lithospheric thickening takes place in the weaker regions. This is best shown by the differences induced in thickening rate in the AB’ section in Fig 7, but we have systematically estimated this effect by defining a measure of strain localization as the standard deviation of the accumulated vertical strain, ε33, at t = 50 Myr relative to its average value. Fig 9 shows how this strain localization changes with the mean wind velocity, the relative humidity and elastic thickness. The speed and humidity of the incoming air induce proportional changes in precipitation and erosion, and higher differences in strain localization. But note that these variations amount to less than 1% relative to the average strain in the entire model, and that even an unsuspected parameter as the elastic thickness of the flexural plate can have a larger effect.


Topographic Evolution and Climate Aridification during Continental Collision: Insights from Computer Simulations.

Garcia-Castellanos D, Jiménez-Munt I - PLoS ONE (2015)

Parameterization.Dependence of the average tectonic strain localization (%) on orographic effects (incoming air humidity RH and mean wind velocity uw) and on the lithospheric elastic thickness. Strain localization is measured as the standard deviation of the accumulated vertical strain (dimensionless). Note that although the changes in this averaged are smaller than 1%, strain rates can locally be enhanced by 50% in areas of rapid erosion (Fig 7a). The reference setup is located with a circle.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4526229&req=5

pone.0132252.g009: Parameterization.Dependence of the average tectonic strain localization (%) on orographic effects (incoming air humidity RH and mean wind velocity uw) and on the lithospheric elastic thickness. Strain localization is measured as the standard deviation of the accumulated vertical strain (dimensionless). Note that although the changes in this averaged are smaller than 1%, strain rates can locally be enhanced by 50% in areas of rapid erosion (Fig 7a). The reference setup is located with a circle.
Mentions: The results show that structural rheological contrasts such as the pre-existence of stronger lithospheric domains in the plate are more relevant in determining the localization of deformation, sedimentary basins, and topographic highs and lows, in front of climatic/erosional heterogeneities (note the similar overall topographic patterns predicted in all models in Fig 5). Orographically focalized erosion can locally modify by up to 50% the rates at which the lithospheric thickening takes place in the weaker regions. This is best shown by the differences induced in thickening rate in the AB’ section in Fig 7, but we have systematically estimated this effect by defining a measure of strain localization as the standard deviation of the accumulated vertical strain, ε33, at t = 50 Myr relative to its average value. Fig 9 shows how this strain localization changes with the mean wind velocity, the relative humidity and elastic thickness. The speed and humidity of the incoming air induce proportional changes in precipitation and erosion, and higher differences in strain localization. But note that these variations amount to less than 1% relative to the average strain in the entire model, and that even an unsuspected parameter as the elastic thickness of the flexural plate can have a larger effect.

Bottom Line: For this purpose, we combine in a single computer program: 1) a thin-sheet viscous model of continental deformation; 2) a stream-power surface-transport approach; 3) flexural isostasy allowing for the formation of large sedimentary foreland basins; and 4) an orographic precipitation model that reproduces basic climatic effects such as continentality and rain shadow.At the continental scale, however, the overall distribution of topographic basins and ranges seems insensitive to climatic factors, despite these do have important, sometimes counterintuitive effects on the amount of sediments trapped within the continent.These complex climatic-drainage-tectonic interactions make the development of steady-state topography at the continental scale unlikely.

View Article: PubMed Central - PubMed

Affiliation: Group of Dynamics of the Lithosphere, Instituto de Ciencias de la Tierra Jaume Almera (ICTJA-CSIC), Barcelona, Spain.

ABSTRACT
How do the feedbacks between tectonics, sediment transport and climate work to shape the topographic evolution of the Earth? This question has been widely addressed via numerical models constrained with thermochronological and geomorphological data at scales ranging from local to orogenic. Here we present a novel numerical model that aims at reproducing the interaction between these processes at the continental scale. For this purpose, we combine in a single computer program: 1) a thin-sheet viscous model of continental deformation; 2) a stream-power surface-transport approach; 3) flexural isostasy allowing for the formation of large sedimentary foreland basins; and 4) an orographic precipitation model that reproduces basic climatic effects such as continentality and rain shadow. We quantify the feedbacks between these processes in a synthetic scenario inspired by the India-Asia collision and the growth of the Tibetan Plateau. We identify a feedback between erosion and crustal thickening leading locally to a <50% increase in deformation rates in places where orographic precipitation is concentrated. This climatically-enhanced deformation takes place preferentially at the upwind flank of the growing plateau, specially at the corners of the indenter (syntaxes). We hypothesize that this may provide clues for better understanding the mechanisms underlying the intriguing tectonic aneurisms documented in the Himalayas. At the continental scale, however, the overall distribution of topographic basins and ranges seems insensitive to climatic factors, despite these do have important, sometimes counterintuitive effects on the amount of sediments trapped within the continent. The dry climatic conditions that naturally develop in the interior of the continent, for example, trigger large intra-continental sediment trapping at basins similar to the Tarim Basin because they determine its endorheic/exorheic drainage. These complex climatic-drainage-tectonic interactions make the development of steady-state topography at the continental scale unlikely.

No MeSH data available.


Related in: MedlinePlus