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Paolo Billi - One of the best experts on this subject based on the ideXlab platform.
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geomorphology of ephemeral streams in the kobo Basin
2015Co-Authors: Paolo BilliAbstract:The Structural Basin of Kobo (northern Ethiopia) is characterised by a semi-arid, monsoon-affected climate, and it is drained by ephemeral streams. The Basin is physiographycally asymmetric with the highest mountains along the western margin where the largest rivers originate. The river morphology well matches the ideal model proposed by Schumm (The fluvial system. Wiley, New York, 1977), consisting of the headwater, the main trunk channel and the distributary system which represents the river terminus where the whole of the water flow vanishes due to infiltration and large amounts of sediment are deposited. The main geomorphic characteristics of the main stem and the distributary systems are described. The study river streambed is flat, devoid of any bedforms and horizontal and planar lamination is by far the most common sedimentary structure. Though in a few study reaches the Froude number calculated for bankfull discharge results steadily around one, i.e. in agreement with the extensive occurrence of the upper plane bed, the occurrence of outsized particles standing on or protruding from the streambed, travelling for long distances on the bed surface and showing no flow perturbation in the fine sediment in their vicinity, is interpreted by a new model of division association capable of explaining the typical division association observed in the study river deposits. It is characterised by large boulders rooted in a core coarse layer and the ubiquitous occurrence of horizontal lamination is interpreted in terms of vertical distribution of shear stress, hyperconcentrated flow and traction carpet processes.
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bedforms and sediment transport processes in the ephemeral streams of kobo Basin northern ethiopia
Catena, 2008Co-Authors: Paolo BilliAbstract:Abstract Bedforms and channel deposits architecture were studied in the ephemeral streams of the Structural Basin of Kobo in northern Ethiopia. The Froude numbers, calculated at bankfull flow for a few of the study reaches, are in agreement with the extensive occurrence of horizontal, planar lamination. Small bedforms, not previously reported in the literature, are found and described as produced mainly by scouring rather than accretion processes. Equations to predict particle entrainment proved that large, individual boulders standing scattered on the stream bed can be transported at bankfull flow for long distances. Direct inspection of the old alluvium and the modern channel deposits allow to identify a typical arrangement within a single bed consisting of divisions with specific characteristics. This model of division association is explained in terms of vertical distribution of shear stress and compared with hyperconcentrated flow and traction carpet models in contrast with recent theories of flat asymmetrical bed waves progradation at Froude numbers close to unity.
Gharabeigli G. - One of the best experts on this subject based on the ideXlab platform.
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Tectono-sedimentary evolution of the Dehdasht Structural Basin (Central Zagros, Iran)
'Elsevier BV', 2021Co-Authors: Heydarzadeh K., Vergés Jaume, Hajialibeigi H., Gharabeigli G.Abstract:This paper deals with the tectono-sedimentary evolution of the Dehdasht Basin, located at the boundary between the Izeh Zone and the Dezful Embayment, in the Central Zagros. The Structural evolution of the Basin is closely related to the coeval sedimentation of Neogene Fars Group foreland Basin deposits. The analysis of five geological cross-sections reveals the interaction between tectonics, Gachsaran Formation diapirism and coeval sedimentation as well as the influence of hidden basement-involved faults. The great thickness of the Miocene Gachsaran evaporites contributes to the internal structure of the Dehdasht Basin as well as decouples the Competent Group structure at depth from the Passive Group structure cropping out at surface. The Basin forms a synclinorium limited by high amplitude NW-SE trending anticlines filled with Neogene deposits. Its internal structure is characterized by relatively thin growth synclines-miniBasins separated by Gachsaran diapiric ridges formed under a combination of shortening and diapirism. The amount of shortening across the Basin ranges between 7.5 and 13.1 km (16–24%) whereas the restored preserved thickness of Gachsaran evaporites increases southeastwards from 2 to 2.85 km. This high thickness is interpreted as partly accumulated by gravity gliding from the rising surrounding anticlines. Observed changes in Structural relief across and along the Dehdasht Basin suggests its development above an array of hidden and linked basement faults including segments of the Mountain Frontal Flexure with NW-SE Zagros trend under the northern and southern boundary anticlines and a transfer fault with N-S Arabian trends at the SE border. The observed Structural variations both along-strike and across the Dehdasht Basin at a local scale are similar to those already found at larger scales along the major Kazerun Fault Zone.This study is part of the PhD dissertation of the first author (KH) at Shahid Beheshti University, Iran, and was partly developed during her scientific stay in the Geosciences Barcelona-CSIC. HH is supported by Shahid Beheshti University [grant No. D/600/3019]. The Faculty of Earth Sciences and Research Department of the Shahid Beheshti University is gratefully acknowledged.Peer reviewe
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Evolution of a Structural Basin: Numerical modelling applied to the Dehdasht Basin, Central Zagros, Iran
'Elsevier BV', 2019Co-Authors: Heydarzadeh K., Ruh, Jonas Bruno, Vergés Jaume, Hajialibeigi H., Gharabeigli G.Abstract:The Dehdasht Basin, a small Structural Basin located in the southeast of the Dezful Embayment in the Zagros fold-and-thrust belt, has a complex tectonic structure characterized by both compressional and halokinetic features. 2D numerical models are used to test how geometrical and rheological parameters affected the Miocene-Pliocene evolution of this deep Basin. The analysed parameters include rates of syntectonic sedimentation and erosion, thickness and viscosity of the lower detachment (Hormuz salt) and of the upper detachment (Gachsaran evaporites) developing diapiric salt walls, salt extrusions and miniBasins-growth synclines that characterize the internal structure of the Dehdasht Basin. Assuming reasonable dimensions and rheologies (0.5 km Hormuz basal detachment with moderate viscosity of 1019 Pa·s, and Gachsaran upper detachment with a minimum original thickness of 1.5 km and viscosity between 5 · 1018 and 1019 Pa·s), our models reveals that an almost intermediate ratio between the rates of surface processes and deformation well approximate the geological and geophysical observations. A local decrease in the thickness of the Hormuz salt below the Dehdasht Basin with respect to surrounding regions was of great importance for its Structural evolution. We suggest that the large volume of Gachsaran evaporites presently filling the Basin was partly due to their gravitational flow from the emerging surrounding anticlines into the Basin. The numerical experiments also demonstrate that in a compressional setting, shortening is the main factor for the rapid initial growth of the diapirs, although, with increasing syntectonic sedimentation the effect of shortening diminishes.JBR was supported by the Swiss National Science Foundation [Grant nr 2-77297-15 ]. This research has been partially funded by projects Alpimed ( PIE-CSIC-201530E082 ) and Subtetis ( PIE-CSIC-201830E039 ).Peer reviewe
Heydarzadeh K. - One of the best experts on this subject based on the ideXlab platform.
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Tectono-sedimentary evolution of the Dehdasht Structural Basin (Central Zagros, Iran)
'Elsevier BV', 2021Co-Authors: Heydarzadeh K., Vergés Jaume, Hajialibeigi H., Gharabeigli G.Abstract:This paper deals with the tectono-sedimentary evolution of the Dehdasht Basin, located at the boundary between the Izeh Zone and the Dezful Embayment, in the Central Zagros. The Structural evolution of the Basin is closely related to the coeval sedimentation of Neogene Fars Group foreland Basin deposits. The analysis of five geological cross-sections reveals the interaction between tectonics, Gachsaran Formation diapirism and coeval sedimentation as well as the influence of hidden basement-involved faults. The great thickness of the Miocene Gachsaran evaporites contributes to the internal structure of the Dehdasht Basin as well as decouples the Competent Group structure at depth from the Passive Group structure cropping out at surface. The Basin forms a synclinorium limited by high amplitude NW-SE trending anticlines filled with Neogene deposits. Its internal structure is characterized by relatively thin growth synclines-miniBasins separated by Gachsaran diapiric ridges formed under a combination of shortening and diapirism. The amount of shortening across the Basin ranges between 7.5 and 13.1 km (16–24%) whereas the restored preserved thickness of Gachsaran evaporites increases southeastwards from 2 to 2.85 km. This high thickness is interpreted as partly accumulated by gravity gliding from the rising surrounding anticlines. Observed changes in Structural relief across and along the Dehdasht Basin suggests its development above an array of hidden and linked basement faults including segments of the Mountain Frontal Flexure with NW-SE Zagros trend under the northern and southern boundary anticlines and a transfer fault with N-S Arabian trends at the SE border. The observed Structural variations both along-strike and across the Dehdasht Basin at a local scale are similar to those already found at larger scales along the major Kazerun Fault Zone.This study is part of the PhD dissertation of the first author (KH) at Shahid Beheshti University, Iran, and was partly developed during her scientific stay in the Geosciences Barcelona-CSIC. HH is supported by Shahid Beheshti University [grant No. D/600/3019]. The Faculty of Earth Sciences and Research Department of the Shahid Beheshti University is gratefully acknowledged.Peer reviewe
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Evolution of a Structural Basin: Numerical modelling applied to the Dehdasht Basin, Central Zagros, Iran
'Elsevier BV', 2019Co-Authors: Heydarzadeh K., Ruh, Jonas Bruno, Vergés Jaume, Hajialibeigi H., Gharabeigli G.Abstract:The Dehdasht Basin, a small Structural Basin located in the southeast of the Dezful Embayment in the Zagros fold-and-thrust belt, has a complex tectonic structure characterized by both compressional and halokinetic features. 2D numerical models are used to test how geometrical and rheological parameters affected the Miocene-Pliocene evolution of this deep Basin. The analysed parameters include rates of syntectonic sedimentation and erosion, thickness and viscosity of the lower detachment (Hormuz salt) and of the upper detachment (Gachsaran evaporites) developing diapiric salt walls, salt extrusions and miniBasins-growth synclines that characterize the internal structure of the Dehdasht Basin. Assuming reasonable dimensions and rheologies (0.5 km Hormuz basal detachment with moderate viscosity of 1019 Pa·s, and Gachsaran upper detachment with a minimum original thickness of 1.5 km and viscosity between 5 · 1018 and 1019 Pa·s), our models reveals that an almost intermediate ratio between the rates of surface processes and deformation well approximate the geological and geophysical observations. A local decrease in the thickness of the Hormuz salt below the Dehdasht Basin with respect to surrounding regions was of great importance for its Structural evolution. We suggest that the large volume of Gachsaran evaporites presently filling the Basin was partly due to their gravitational flow from the emerging surrounding anticlines into the Basin. The numerical experiments also demonstrate that in a compressional setting, shortening is the main factor for the rapid initial growth of the diapirs, although, with increasing syntectonic sedimentation the effect of shortening diminishes.JBR was supported by the Swiss National Science Foundation [Grant nr 2-77297-15 ]. This research has been partially funded by projects Alpimed ( PIE-CSIC-201530E082 ) and Subtetis ( PIE-CSIC-201830E039 ).Peer reviewe
Vergés Jaume - One of the best experts on this subject based on the ideXlab platform.
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Tectono-sedimentary evolution of the Dehdasht Structural Basin (Central Zagros, Iran)
'Elsevier BV', 2021Co-Authors: Heydarzadeh K., Vergés Jaume, Hajialibeigi H., Gharabeigli G.Abstract:This paper deals with the tectono-sedimentary evolution of the Dehdasht Basin, located at the boundary between the Izeh Zone and the Dezful Embayment, in the Central Zagros. The Structural evolution of the Basin is closely related to the coeval sedimentation of Neogene Fars Group foreland Basin deposits. The analysis of five geological cross-sections reveals the interaction between tectonics, Gachsaran Formation diapirism and coeval sedimentation as well as the influence of hidden basement-involved faults. The great thickness of the Miocene Gachsaran evaporites contributes to the internal structure of the Dehdasht Basin as well as decouples the Competent Group structure at depth from the Passive Group structure cropping out at surface. The Basin forms a synclinorium limited by high amplitude NW-SE trending anticlines filled with Neogene deposits. Its internal structure is characterized by relatively thin growth synclines-miniBasins separated by Gachsaran diapiric ridges formed under a combination of shortening and diapirism. The amount of shortening across the Basin ranges between 7.5 and 13.1 km (16–24%) whereas the restored preserved thickness of Gachsaran evaporites increases southeastwards from 2 to 2.85 km. This high thickness is interpreted as partly accumulated by gravity gliding from the rising surrounding anticlines. Observed changes in Structural relief across and along the Dehdasht Basin suggests its development above an array of hidden and linked basement faults including segments of the Mountain Frontal Flexure with NW-SE Zagros trend under the northern and southern boundary anticlines and a transfer fault with N-S Arabian trends at the SE border. The observed Structural variations both along-strike and across the Dehdasht Basin at a local scale are similar to those already found at larger scales along the major Kazerun Fault Zone.This study is part of the PhD dissertation of the first author (KH) at Shahid Beheshti University, Iran, and was partly developed during her scientific stay in the Geosciences Barcelona-CSIC. HH is supported by Shahid Beheshti University [grant No. D/600/3019]. The Faculty of Earth Sciences and Research Department of the Shahid Beheshti University is gratefully acknowledged.Peer reviewe
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Evolution of a Structural Basin: Numerical modelling applied to the Dehdasht Basin, Central Zagros, Iran
'Elsevier BV', 2019Co-Authors: Heydarzadeh K., Ruh, Jonas Bruno, Vergés Jaume, Hajialibeigi H., Gharabeigli G.Abstract:The Dehdasht Basin, a small Structural Basin located in the southeast of the Dezful Embayment in the Zagros fold-and-thrust belt, has a complex tectonic structure characterized by both compressional and halokinetic features. 2D numerical models are used to test how geometrical and rheological parameters affected the Miocene-Pliocene evolution of this deep Basin. The analysed parameters include rates of syntectonic sedimentation and erosion, thickness and viscosity of the lower detachment (Hormuz salt) and of the upper detachment (Gachsaran evaporites) developing diapiric salt walls, salt extrusions and miniBasins-growth synclines that characterize the internal structure of the Dehdasht Basin. Assuming reasonable dimensions and rheologies (0.5 km Hormuz basal detachment with moderate viscosity of 1019 Pa·s, and Gachsaran upper detachment with a minimum original thickness of 1.5 km and viscosity between 5 · 1018 and 1019 Pa·s), our models reveals that an almost intermediate ratio between the rates of surface processes and deformation well approximate the geological and geophysical observations. A local decrease in the thickness of the Hormuz salt below the Dehdasht Basin with respect to surrounding regions was of great importance for its Structural evolution. We suggest that the large volume of Gachsaran evaporites presently filling the Basin was partly due to their gravitational flow from the emerging surrounding anticlines into the Basin. The numerical experiments also demonstrate that in a compressional setting, shortening is the main factor for the rapid initial growth of the diapirs, although, with increasing syntectonic sedimentation the effect of shortening diminishes.JBR was supported by the Swiss National Science Foundation [Grant nr 2-77297-15 ]. This research has been partially funded by projects Alpimed ( PIE-CSIC-201530E082 ) and Subtetis ( PIE-CSIC-201830E039 ).Peer reviewe
Hajialibeigi H. - One of the best experts on this subject based on the ideXlab platform.
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Tectono-sedimentary evolution of the Dehdasht Structural Basin (Central Zagros, Iran)
'Elsevier BV', 2021Co-Authors: Heydarzadeh K., Vergés Jaume, Hajialibeigi H., Gharabeigli G.Abstract:This paper deals with the tectono-sedimentary evolution of the Dehdasht Basin, located at the boundary between the Izeh Zone and the Dezful Embayment, in the Central Zagros. The Structural evolution of the Basin is closely related to the coeval sedimentation of Neogene Fars Group foreland Basin deposits. The analysis of five geological cross-sections reveals the interaction between tectonics, Gachsaran Formation diapirism and coeval sedimentation as well as the influence of hidden basement-involved faults. The great thickness of the Miocene Gachsaran evaporites contributes to the internal structure of the Dehdasht Basin as well as decouples the Competent Group structure at depth from the Passive Group structure cropping out at surface. The Basin forms a synclinorium limited by high amplitude NW-SE trending anticlines filled with Neogene deposits. Its internal structure is characterized by relatively thin growth synclines-miniBasins separated by Gachsaran diapiric ridges formed under a combination of shortening and diapirism. The amount of shortening across the Basin ranges between 7.5 and 13.1 km (16–24%) whereas the restored preserved thickness of Gachsaran evaporites increases southeastwards from 2 to 2.85 km. This high thickness is interpreted as partly accumulated by gravity gliding from the rising surrounding anticlines. Observed changes in Structural relief across and along the Dehdasht Basin suggests its development above an array of hidden and linked basement faults including segments of the Mountain Frontal Flexure with NW-SE Zagros trend under the northern and southern boundary anticlines and a transfer fault with N-S Arabian trends at the SE border. The observed Structural variations both along-strike and across the Dehdasht Basin at a local scale are similar to those already found at larger scales along the major Kazerun Fault Zone.This study is part of the PhD dissertation of the first author (KH) at Shahid Beheshti University, Iran, and was partly developed during her scientific stay in the Geosciences Barcelona-CSIC. HH is supported by Shahid Beheshti University [grant No. D/600/3019]. The Faculty of Earth Sciences and Research Department of the Shahid Beheshti University is gratefully acknowledged.Peer reviewe
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Evolution of a Structural Basin: Numerical modelling applied to the Dehdasht Basin, Central Zagros, Iran
'Elsevier BV', 2019Co-Authors: Heydarzadeh K., Ruh, Jonas Bruno, Vergés Jaume, Hajialibeigi H., Gharabeigli G.Abstract:The Dehdasht Basin, a small Structural Basin located in the southeast of the Dezful Embayment in the Zagros fold-and-thrust belt, has a complex tectonic structure characterized by both compressional and halokinetic features. 2D numerical models are used to test how geometrical and rheological parameters affected the Miocene-Pliocene evolution of this deep Basin. The analysed parameters include rates of syntectonic sedimentation and erosion, thickness and viscosity of the lower detachment (Hormuz salt) and of the upper detachment (Gachsaran evaporites) developing diapiric salt walls, salt extrusions and miniBasins-growth synclines that characterize the internal structure of the Dehdasht Basin. Assuming reasonable dimensions and rheologies (0.5 km Hormuz basal detachment with moderate viscosity of 1019 Pa·s, and Gachsaran upper detachment with a minimum original thickness of 1.5 km and viscosity between 5 · 1018 and 1019 Pa·s), our models reveals that an almost intermediate ratio between the rates of surface processes and deformation well approximate the geological and geophysical observations. A local decrease in the thickness of the Hormuz salt below the Dehdasht Basin with respect to surrounding regions was of great importance for its Structural evolution. We suggest that the large volume of Gachsaran evaporites presently filling the Basin was partly due to their gravitational flow from the emerging surrounding anticlines into the Basin. The numerical experiments also demonstrate that in a compressional setting, shortening is the main factor for the rapid initial growth of the diapirs, although, with increasing syntectonic sedimentation the effect of shortening diminishes.JBR was supported by the Swiss National Science Foundation [Grant nr 2-77297-15 ]. This research has been partially funded by projects Alpimed ( PIE-CSIC-201530E082 ) and Subtetis ( PIE-CSIC-201830E039 ).Peer reviewe
