scholarly journals The influence of upper-plate advance and erosion on overriding plate deformation in orogen syntaxes

Solid Earth ◽  
2018 ◽  
Vol 9 (6) ◽  
pp. 1207-1224 ◽  
Author(s):  
Matthias Nettesheim ◽  
Todd A. Ehlers ◽  
David M. Whipp ◽  
Alexander Koptev
Keyword(s):  
Shear Zones ◽  
Climatic Conditions ◽  
Tectonic Uplift ◽  
Lithostatic Pressure ◽  
Fluvial Erosion ◽  
Plate Deformation ◽  
Driving Mechanisms ◽  
Dip Angle ◽  
Basal Detachment ◽  
Indenter Geometry

Abstract. Focused, rapid exhumation of rocks is observed at some orogen syntaxes, but the driving mechanisms remain poorly understood and contested. In this study, we use a fully coupled thermomechanical numerical model to investigate the effect of upper-plate advance and different erosion scenarios on overriding plate deformation. The subducting slab in the model is curved in 3-D, analogous to the indenter geometry observed in seismic studies. We find that the amount of upper-plate advance toward the trench dramatically changes the orientation of major shear zones in the upper plate and the location of rock uplift. Shear along the subduction interface facilitates the formation of a basal detachment situated above the indenter, causing localized rock uplift there. We conclude that the change in orientation and dip angle set by the indenter geometry creates a region of localized uplift as long as subduction of the down-going plate is active. Switching from flat (total) erosion to more realistic fluvial erosion using a landscape evolution model leads to variations in rock uplift at the scale of large catchments. In this case, deepest exhumation again occurs above the indenter apex, but tectonic uplift is modulated on even smaller scales by lithostatic pressure from the overburden of the growing orogen. Highest rock uplift can occur when a strong tectonic uplift field spatially coincides with large erosion potential. This implies that both the geometry of the subducting plate and the geomorphic and climatic conditions are important for the creation of focused, rapid exhumation.

scholarly journals The influence of subducting slab advance and erosion on overriding plate deformation in orogen syntaxes

2018 ◽  
Author(s):  
Matthias Nettesheim ◽  
Todd A. Ehlers ◽  
David M. Whipp ◽  
Alexander Koptev
Keyword(s):  
Shear Zones ◽  
Climatic Conditions ◽  
Tectonic Uplift ◽  
Lithostatic Pressure ◽  
Catchment Scale ◽  
Plate Deformation ◽  
Driving Mechanisms ◽  
Dip Angle ◽  
Subducting Slab ◽  
Indenter Geometry

Abstract. Focused, rapid exhumation of rocks is observed at some plate corners, but the driving mechanisms remain poorly understood and contested. In this study, we use a fully coupled thermo-mechanical numerical model to investigate the effect of slab advance and different erosion scenarios on overriding plate deformation. The subducting slab in the model is curved in 3D, analogous to the indenter geometry observed in seismic studies. We find that the amount of slab advance dramatically changes the orientation of major shear zones in the upper plate and the location of rock uplift zones. Shear along the subduction interface facilitates the formation of a basal detachment situated above the indenter, causing localized rock uplift there. Switching from flat (total erosion) to more realistic fluvial erosion leads to variation of rock uplift on the catchment-scale. Here, deepest exhumation again occurred above the indenter apex. We conclude that the change in orientation and dip angle set by the indenter geometry facilitates creation of localized uplift regions as long as subduction of the down-going plate is active. Tectonic uplift is modulated on even smaller scales by lithostatic pressure from the overburden of the growing orogen, and highest rock uplift can occur when a strong tectonic uplift field spatially coincides with large erosion potential. This implies that both the geometry of the subducting plate and the geomorphic and climatic conditions are important for the creation of focused, rapid exhumation.

scholarly journals Geomorphological indicators of large-scale climatic changes in the Eastern Bolivian lowlands

2006 ◽  
Vol 61 (2) ◽  
pp. 120-134 ◽  
Author(s):  
J. May
Keyword(s):  
South America ◽  
Large Scale ◽  
Climate Changes ◽  
Landscape Evolution ◽  
Spatial Scales ◽  
Climatic Changes ◽  
Climatic Conditions ◽  
Fluvial Erosion ◽  
Paleoclimatic Significance ◽  
Bolivian Lowlands

Abstract. This study provides an inventory of geomorphological landforms in Eastern Bolivia at different spatial scales. Landforms and associated processes are interpreted and discussed regarding landscape evolution and paleoclimatic significance. Thereby, preliminary conclusions about past climate changes and the geomorphic evolution in Eastern Bolivia can be provided. Fluvial and aeolian processes are presently restricted to a few locations in the study area. A much more active landscape has been inferred from large-scale Channel shifts and extensive paleodune Systems. Mobilization. transport and deposition of Sediments are thought to be the result of climatic conditions drier than today. However. there are also indications of formerly wetter conditions such as fluvial erosion and paleolake basins. In conclusion, the documentation and interpretation of the manifold landforms has shown to contain a considerable amount of paleoecological information, which might serve as the base for further paleoclimatic research in the central part of tropical South America.

scholarly journals Tesserae on Venus may preserve evidence of fluvial erosion

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
S. Khawja ◽  
R. E. Ernst ◽  
C. Samson ◽  
P. K. Byrne ◽  
R. C. Ghail ◽  
...  
Keyword(s):  
Climate Models ◽  
High Surface ◽  
Climatic Conditions ◽  
Tectonic Deformation ◽  
Fluvial Erosion ◽  
Global Circulation ◽  
Global Circulation Models ◽  
Research Theme ◽  
Wet Climate ◽  
Indirect Technique

AbstractFluvial erosion is usually assumed to be absent on Venus, precluded by a high surface temperature of ~450 °C and supported by extensive uneroded volcanic flows. However, recent global circulation models suggest the possibility of Earth-like climatic conditions on Venus for much of its earlier history, prior to catastrophic runaway greenhouse warming. We observe that the stratigraphically oldest, geologically most complex units, tesserae, exhibit valley patterns morphologically similar to the patterns resulting from fluvial erosion on Earth. Given poor topographic resolution, we use an indirect technique to recognize valleys, based on the pattern of lava flooding of tesserae margins by adjacent plains volcanism. These observed valley patterns are attributed to primary geology, tectonic deformation, followed by fluvial erosion (and lesser wind erosion). This proposed fluvial erosion in tesserae provides support for climate models for a cool, wet climate on early Venus and could be an attractive research theme for future Venus missions.

scholarly journals Drivers of an epic radiation: the role of climate and islands in species diversification and reproductive-mode evolution of Old-World tree frogs

2021 ◽  
Author(s):  
Gajaba Ellepola ◽  
Marcio R. Pie ◽  
Rohan Pethiyagoda ◽  
James Hanken ◽  
Madhava Meegaskumbura
Keyword(s):  
Reproductive Mode ◽  
Late Eocene ◽  
Climatic Conditions ◽  
Centre Of Origin ◽  
Driving Mechanisms ◽  
Climate Niche ◽  
Continental Islands ◽  
Evolutionary Lineages ◽  
Key Innovations

Although large diversifications of species occur unevenly across space and evolutionary lineages, the relative importance of their driving mechanisms, such as climate, ecological opportunity and key innovations, remains poorly understood. Here, we explore the remarkable diversification of rhacophorid frogs, which represent six percent of global amphibian diversity, utilize four distinct reproductive modes, and span a climatically variable area across mainland Asia, associated continental islands, and Africa. Using a complete species-level phylogeny, we find near-constant diversification rates but a highly uneven distribution of species richness. Montane regions on islands and some mainland regions have higher phylogenetic diversity and unique assemblages of taxa; we identify these as cool-wet refugia. Starting from a centre of origin, rhacophorids reached these distant refugia by adapting to new climatic conditions (niche evolution-dominant), especially following the origin of key innovations such as terrestrial reproduction (in the Late Eocene) or by dispersal during periods of favourable climate (niche conservatism-dominant).

Provenance Characterization and Palaeoenvironmental Analysis of the Meta-Sedimentary Rocks of Sonaghati Formation, Betul District, Madhya Pradesh Using Geochemical Approach

2021 ◽  
Vol 38 (1) ◽  
pp. 75-92
Author(s):  
Shradha Shukla
Keyword(s):  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Shear Zones ◽  
Climatic Conditions ◽  
Compositional Variation ◽  
Genetic Population ◽  
Tectonic Zone ◽  
Geochemical Composition ◽  
Chemical Index ◽  
Semi Arid

Betul belt, ENE-WSW trending, 135 km long, prominent litho-tectonic unit exposed in the central part of Central Indian Tectonic Zone (CITZ) is composed of meta-sedimentary & meta-volcanic rocks intruded by mafic-ultramafic and granitic suite of rocks, belonging to Palaeoproterozoic to Neoproterozoic age. This belt is traversed by several ENE-WSW trending, sub-vertical ductite shear zones. The meta-sedimentary rocks of Sonaghati Formation were geochemically characterized and their geochemical composition was interpreted for provenance characterization and paleo-environmental assessment. The weathering indices including Chemical index of Alteration, Chemical index of Weathering, Plagioclase Index of Alteration and Weathering Index of Parker indicate that theses meta-sedimentary rocks have witnessed the substantial amount of weathering at the source without any evidence of potash metasomatism. The Bivariate plots using the major and trace element composition show co-linear trends, which reflect that all these samples belong to co-genetic population and the visible compositional variation could be attributed to chemical, mineralogical and textural maturity. The Sonaghati metasedimentary rocks are enriched in REE with negative Eu anomaly. The LREE enrichment varies from 122 to 174 times and that of the HREE enrichment ranges from 12 to 31 times of Chondrite indicating highly varied protoliths. The provenance characterization was attempted using the large ion lithophile elements and high field strength elements. The results show that the precursor for these meta-sedimentary litho-units are mixed source with the major contributor being felsic to intermediate and minor contribution has come from the mafic end members. These meta-sedimentary rocks were deposited in the overall semi arid climate with a sequential transition, suggesting the variable climatic conditions ranging from semi-arid to arid. The Cu/Zn, V/Cr ratios, and presence of pyrites dissemination and stringers eventually indicate the prevalence of reducing environmental conditions during the deposition of these meta-sediments.

scholarly journals Large Scale Terrain Generation from Tectonic Uplift and Fluvial Erosion

2016 ◽  
Vol 35 (2) ◽  
pp. 165-175 ◽  
Author(s):  
Guillaume Cordonnier ◽  
Jean Braun ◽  
Marie-Paule Cani ◽  
Bedrich Benes ◽  
Éric Galin ◽  
...  
Keyword(s):  
Large Scale ◽  
Tectonic Uplift ◽  
Fluvial Erosion ◽  
Terrain Generation

scholarly journals Magnetic anomaly interpretation for a 2D fault-like geologic structures utilizing the global particle swarm method

2021 ◽  
Author(s):  
Khalid S. ESSA ◽  
Yves Géraud ◽  
Alan B. Reid
Keyword(s):  
Magnetic Anomaly ◽  
Goodness Of Fit ◽  
Moving Average ◽  
Particle Swarm ◽  
Theoretical Models ◽  
Shear Zones ◽  
Real Field ◽  
Fault Parameters ◽  
Particle Swarm Method ◽  
Dip Angle

Abstract We establish a method to elucidate the magnetic anomaly due to 2D fault structures, with an evaluation of first moving average residual anomalies utilizing filters of increasing window lengths. After that, the buried fault parameters are estimated using the global particle swarm method. The goodness of fit among the observed and the calculated models is expressed as the root mean squared (RMS) error. The importance of studying and delineating the fault parameters, which include the amplitude factor, the depth to the upper edge, the depth to the lower edge, the fault dip angle, and the position of the origin of the fault, is: (i) solving many problem-related engineering and environmental applications, (ii) describing the accompanying mineralized zones with faults, (iii) describing geological deformation events, (iv) monitoring the subsurface shear zones, (v) defining the environmental effects of the faults before organizing any investments, and (vi) imaging subsurface faults for different scientific studies. Finally, we show the method applied to two theoretical models including the influence of the regional background and the multi-fault effect and to real field examples from Australia and Turkey. Available geologic and geophysical information corroborates our interpretations.

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