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Liu Shaofeng - One of the best experts on this subject based on the ideXlab platform.
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pleistocene Paleosurface reconstruction and holocen erosion quantity calculation for guide gonghe tongde basin complex qinghai
Remote Sensing for Land & Resources, 2013Co-Authors: Liu ShaofengAbstract:The Guide-Gonghe-Tongde basin complex is located along the northeast marginal zone of the Tibetan Plateau.The Yellow River flows through these three basins.For understanding the tectonic and climatic indications of the fluvial erosion of the three basins since Holocene,the authors calculated the erosion quantity by using geological cross sections combined with digital elevation model(DEM).First,the points selected for the interpolation were picked out manually from a series of geological profiles.The minimum Pleistocene surfaces were reconstructed within the basins.This method reduced the error caused by the erosion after the deposition.Second,the erosion quantity and the erosion rates since Holocene were obtained by subtracting the modern elevation from the reconstructed surface.The results show that the erosion rate increased from upstream basin(Tongde basin) to downstream basin(Guide basin).The spatial erosion differences may indicate that the uplift of the margin of the Tibetan Plateau was greater than that of the inner part of the plateau.
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Pleistocene Paleosurface reconstruction and Holocen erosion quantity calculation for Guide—Gonghe—Tongde basin complex,Qinghai
Remote Sensing for Land & Resources, 2013Co-Authors: Liu ShaofengAbstract:The Guide-Gonghe-Tongde basin complex is located along the northeast marginal zone of the Tibetan Plateau.The Yellow River flows through these three basins.For understanding the tectonic and climatic indications of the fluvial erosion of the three basins since Holocene,the authors calculated the erosion quantity by using geological cross sections combined with digital elevation model(DEM).First,the points selected for the interpolation were picked out manually from a series of geological profiles.The minimum Pleistocene surfaces were reconstructed within the basins.This method reduced the error caused by the erosion after the deposition.Second,the erosion quantity and the erosion rates since Holocene were obtained by subtracting the modern elevation from the reconstructed surface.The results show that the erosion rate increased from upstream basin(Tongde basin) to downstream basin(Guide basin).The spatial erosion differences may indicate that the uplift of the margin of the Tibetan Plateau was greater than that of the inner part of the plateau.
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a method of reconstructing the Paleosurface based on edm data a case study of the guide basin qinghai china on the northeastern margin of the qinghai tibet plateau
Geological bulletin of China, 2008Co-Authors: Liu ShaofengAbstract:The extensively used digital elevation model (DEM) data make it possible to reconstruct the Paleosurface. In this paper, take the Guide basin for example, several methods for extracting the data of surface exposure samples representing the Paleosurface have been analyzed and compared. The authors propose an optimal method, i.e. the top point representing the original sedimentary strata in the outcrops should be selected as the interpolated sample. They extracted the sample data of the top of the Pleistocene surface outcrop. Based on an analysis of the sample characters and a comparison of the interpolated values, the natural neighbor interpolation has been adopted to reconstruct the Pleistocene Paleosurface of the study area. The error of the reconstructed Paleosurface has been decreased by using the proper interpolation to the properly selected samples. The extraction of correct sample points plus the selection of the proper interpolation have optimized the reconstruction of the Paleosurface.
Balázs Székely - One of the best experts on this subject based on the ideXlab platform.
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Faulted and eroded gravel deposit in western Hungary
2010Co-Authors: Gábor M. Kovács, Tamás Telbisz, Balázs SzékelyAbstract:During the Pleistocene, rivers of the Eastern Alps drained more water into the Pannonian Basin as in recent times. The excess discharge, due to the meltwater of glaciers, transported detrital material from the periglacial areas that built low-relief gravel deposits up in the transitional regions. Today most of these separated gravel plains highly dissected by the frequent, N–S stream network developed in the post-Pleistocene times. Exceptions can also be found, where flat plains form slightly tilted blocks, bordered by W–E steep scarps. Owing to these scarps, streams are unable to incise as deep as in other aforementioned areas, thus these flat plains are expected to represent the nearly intact, Pleistocene Paleosurface.
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The Dachstein Paleosurface and the Augenstein Formation in the Northern Calcareous Alps – a mosaic stone in the geomorphological evolution of the Eastern Alps
International Journal of Earth Sciences, 2001Co-Authors: Wolfgang Frisch, Joachim Kuhlemann, István Dunkl, Balázs SzékelyAbstract:The central and eastern areas of the Northern Calcareous Alps (NCA) are characterized by remnants of the Dachstein Paleosurface, which formed in Late Eocene (?) to Early Oligocene time and is preserved with limited modification on elevated karst plateaus. In Oligocene time, the Dachstein Paleosurface subsided and was sealed by the Augenstein Formation, a terrestrial succession of conglomerates and sandstones, which are only preserved in small remnants on the plateaus, some in an autochthonous position. Thermochronological data suggest a maximum thickness of the Augenstein Formation of >1.3 km, possibly >2 km. The age of the Augenstein Formation is constrained by the overall geological situation as Early Oligocene to earliest Miocene. Fission track age data support an Early Oligocene age of the basal parts of the formation. The source area of the Augenstein Formation consisted predominantly of weakly metamorphic Paleozoic terrains (Greywacke Zone and equivalents) as well as the Late Carboniferous to Scythian siliciclastic base of the NCA to the south of the depositional area. To the west, the Augenstein Formation interfingered with the Tertiary deposits of the Inntal. Sedimentation of the Augenstein Formation was terminated in Early Miocene time in the course of the orogenic collapse of the Eastern Alps. The Augenstein sediments were eroded and redeposited in the foreland Molasse zone. From Pannonian times (~10 Ma) on, the NCA and the denuded Dachstein surface experienced uplift in several pulses. The Dachstein Paleosurface has been preserved in areas, in which thick limestone sequences allowed subsurface erosion by cave formation and thus prevented major surface erosion.
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the dachstein Paleosurface and the augenstein formation in the northern calcareous alps a mosaic stone in the geomorphological evolution of the eastern alps
International Journal of Earth Sciences, 2001Co-Authors: Wolfgang Frisch, Joachim Kuhlemann, István Dunkl, Balázs SzékelyAbstract:The central and eastern areas of the Northern Calcareous Alps (NCA) are characterized by remnants of the Dachstein Paleosurface, which formed in Late Eocene (?) to Early Oligocene time and is preserved with limited modification on elevated karst plateaus. In Oligocene time, the Dachstein Paleosurface subsided and was sealed by the Augenstein Formation, a terrestrial succession of conglomerates and sandstones, which are only preserved in small remnants on the plateaus, some in an autochthonous position. Thermochronological data suggest a maximum thickness of the Augenstein Formation of >1.3 km, possibly >2 km. The age of the Augenstein Formation is constrained by the overall geological situation as Early Oligocene to earliest Miocene. Fission track age data support an Early Oligocene age of the basal parts of the formation. The source area of the Augenstein Formation consisted predominantly of weakly metamorphic Paleozoic terrains (Greywacke Zone and equivalents) as well as the Late Carboniferous to Scythian siliciclastic base of the NCA to the south of the depositional area. To the west, the Augenstein Formation interfingered with the Tertiary deposits of the Inntal. Sedimentation of the Augenstein Formation was terminated in Early Miocene time in the course of the orogenic collapse of the Eastern Alps. The Augenstein sediments were eroded and redeposited in the foreland Molasse zone. From Pannonian times (~10 Ma) on, the NCA and the denuded Dachstein surface experienced uplift in several pulses. The Dachstein Paleosurface has been preserved in areas, in which thick limestone sequences allowed subsurface erosion by cave formation and thus prevented major surface erosion.
Laura Evenstar - One of the best experts on this subject based on the ideXlab platform.
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Geomorphology on geologic timescales: Evolution of the late Cenozoic Pacific Paleosurface in Northern Chile and Southern Peru
Earth-Science Reviews, 2017Co-Authors: Laura Evenstar, Anne E. Mather, Adrian J. Hartley, Finlay M. Stuart, R. S. J. Sparks, Frances J. CooperAbstract:Abstract The Atacama Desert on the western margin of the Central Andes is one of the driest and oldest deserts in the world. It is defined by a distinct and ancient surface, known as the Pacific Paleosurface (PPS) or Atacama Paleosurface. The age of this surface is determined as the time at which sediment deposition ceased, and the surface was effectively abandoned. Early studies suggested that this abandonment took place between 14 and 10 Ma, and was related to both the uplift of the Andes and the onset of hyperaridity in the region. Here we provide a regional re-examination of the PPS, compiling existing work on the underlying geology, sedimentology, surface exposure dating, and seismic profiling. We also present new multispectral satellite maps of the PPS and 45 new cosmogenic 3He and 21Ne surface exposure ages in order to constrain the formation age, and the preservation and incision history of the Paleosurface. We conclude that the PPS is not a single Paleosurface, but instead is a mosaic of smaller surfaces that were formed by aggradational and degradational processes over 19 million years (or more) and should be termed collectively as the Pacific Paleosurfaces. The time at which individual Paleosurfaces formed is related to regional climate, where the location of each is controlled by regional tectonic activity. Cosmogenic surface exposure ages suggest that the surfaces are a record of regional scale climate events.
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Geomorphology on geologic timescales: Evolution of the late Cenozoic Pacific Paleosurface in Northern Chile and Southern Peru
'Elsevier BV', 2017Co-Authors: Laura Evenstar, Ae Mather, Aj Hartley, Fm Stuart, Sparks Rsj, Fj CooperAbstract:publisher: Elsevier articletitle: Geomorphology on geologic timescales: Evolution of the late Cenozoic Pacific Paleosurface in Northern Chile and Southern Peru journaltitle: Earth-Science Reviews articlelink: http://dx.doi.org/10.1016/j.earscirev.2017.04.004 content_type: article copyright: © 2017 Elsevier B.V. All rights reserved
Florias Mees - One of the best experts on this subject based on the ideXlab platform.
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The age of supergene manganese deposits in Katanga and its implications for the Neogene evolution of the African Great Lakes Region
Ore Geology Reviews, 2015Co-Authors: Thierry De Putter, Gilles Ruffet, Johan Yans, Florias MeesAbstract:Supergene manganese deposits commonly contain K-rich Mn oxides with tunnel structure, such as cryptomelane, which are suitable for radiometric dating using the 39Ar–40Ar method. In Africa, Mn deposits have been dated by this method for localities in western and southern parts of the continent, whereas only some preliminary data are available for Central Africa. Herewe present new39Ar–40Ar ages for Mnoxide samples of the Kisenge deposit, in southwestern Katanga, Democratic Republic of the Congo. The samples represent supergene Mn oxide deposits that formed at the expense of primary Paleoproterozoic rhodochrosite-dominated carbonate ores. Main phases of Mn oxide formation are dated at c. 10.5 Ma, 3.6 Ma and 2.6 Ma for a core that crosses a mineralized interval. The latter shows a decrease in age with increasing depth, recording downward penetration of a weathering front. Surface samples of the Kisenge deposits also record a ≥c.19.2 Ma phase, as well as c. 15.7 Ma, 14.2 Ma and 13.6 Ma phases. The obtained ages correspond to distinct periods of Paleosurface development and stability during the Mio-Pliocene in Katanga. Because Katanga is a key area bordered to the North by the Congo Basin and to the East by the East African Rift System, these ages also provide constraints for the geodynamic evolution of the entire region. For the Mio-Pliocene, the Kisenge deposits record ages that are not systematically found elsewhere in Africa, although the 10.5–11 Ma event corresponds to a roughly simultaneous event in the Kalahari Manganese Field, South Africa. The rest of the Katanga Paleosurface record differs somewhat fromrecords for other parts of Africa, forwhich older, Eocene ages have been obtained. This difference is most probably related to the specific regional geodynamic context: uplift of the East African Plateau, with associated erosion, and the opening of the East African Rift System at c. 25 Ma are events whose effects, in the study area, interfere with those of processes responsible for the development of continent-wide Paleosurfaces.
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circumgranular bassanite in a gypsum crust from eastern algeria a potential palaeosurface indicator
Sedimentology, 2003Co-Authors: Florias Mees, Georges StoopsAbstract:Detrital sand grains are surrounded by thin bassanite coatings in the upper part of a coarse-crystalline gypsum crust from the Algerian Sahara. The bassanite developed by topotactic replacement of the surrounding gypsum in the absence of a liquid phase. Heating experiments using a gypsum crystal with sand inclusions produced similar patterns and textures. In one experiment, bassanite developed around quartz and carbonate grains but not along the sides of the heated gypsum crystal. This is the result of differences in heat capacity between gypsum, quartz and calcite. Bassanite formation in the crust from Algeria was not controlled by differences in thermal properties. Instead, the bassanite apparently formed under conditions of thermal equilibrium. The occurrence of bassanite as circumgranular coatings in the crust is interpreted as being related to the availability of submicroscopic space along the contact between the gypsum cement and the enclosed sand grains. The presence of coatings of this type, or derived relict features, is a potential criterion for the recognition of palaeosurfaces.
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Circumgranular bassanite in a gypsum crust from eastern Algeria – a potential palaeosurface indicator
Sedimentology, 2003Co-Authors: Florias Mees, Georges StoopsAbstract:Detrital sand grains are surrounded by thin bassanite coatings in the upper part of a coarse-crystalline gypsum crust from the Algerian Sahara. The bassanite developed by topotactic replacement of the surrounding gypsum in the absence of a liquid phase. Heating experiments using a gypsum crystal with sand inclusions produced similar patterns and textures. In one experiment, bassanite developed around quartz and carbonate grains but not along the sides of the heated gypsum crystal. This is the result of differences in heat capacity between gypsum, quartz and calcite. Bassanite formation in the crust from Algeria was not controlled by differences in thermal properties. Instead, the bassanite apparently formed under conditions of thermal equilibrium. The occurrence of bassanite as circumgranular coatings in the crust is interpreted as being related to the availability of submicroscopic space along the contact between the gypsum cement and the enclosed sand grains. The presence of coatings of this type, or derived relict features, is a potential criterion for the recognition of palaeosurfaces.
Wolfgang Frisch - One of the best experts on this subject based on the ideXlab platform.
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Erosion rates on subalpine Paleosurfaces in the western Mediterranean by in-situ ^10Be concentrations in granites: implications for surface processes and long-term landscape evolution in Corsica (France)
International Journal of Earth Sciences, 2008Co-Authors: Joachim Kuhlemann, Klaas Borg, Paul D. Bons, Martin Danišík, Wolfgang FrischAbstract:A study of erosion rates by in-situ ^10Be concentrations in granites of Miocene high-elevation Paleosurfaces in Corsica indicates maximum erosion rates between 8 and 24 mm/kyear. The regional distribution of measured erosion rates indicates that the local climatic conditions, namely precipitation, the petrographic composition of granites, and the degree of brittle deformation govern erosion rates. Chemical erosion dominates even at elevations around 2,000 m in presently subalpine climate conditions. Field evidence indicates that erosion operates by continuous dissolution and/or disintegration to grains (grusification). The erosion rates are relatively high with respect to the preservation of inferred Early Miocene landscapes. We infer temporal burial in the Middle Miocene and significantly lower erosion rates in the Neogene until ∼3 Ma to explain the preservation of Paleosurfaces, in line with fission track data. Valley incision rates that are a magnitude higher than erosion rates on summit surfaces result in relief enhancement and long-term isostatic surface uplift. On the other hand, widening and deepening of valleys by cyclic glaciation progressively destroys the summit surface relics.
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The Dachstein Paleosurface and the Augenstein Formation in the Northern Calcareous Alps – a mosaic stone in the geomorphological evolution of the Eastern Alps
International Journal of Earth Sciences, 2001Co-Authors: Wolfgang Frisch, Joachim Kuhlemann, István Dunkl, Balázs SzékelyAbstract:The central and eastern areas of the Northern Calcareous Alps (NCA) are characterized by remnants of the Dachstein Paleosurface, which formed in Late Eocene (?) to Early Oligocene time and is preserved with limited modification on elevated karst plateaus. In Oligocene time, the Dachstein Paleosurface subsided and was sealed by the Augenstein Formation, a terrestrial succession of conglomerates and sandstones, which are only preserved in small remnants on the plateaus, some in an autochthonous position. Thermochronological data suggest a maximum thickness of the Augenstein Formation of >1.3 km, possibly >2 km. The age of the Augenstein Formation is constrained by the overall geological situation as Early Oligocene to earliest Miocene. Fission track age data support an Early Oligocene age of the basal parts of the formation. The source area of the Augenstein Formation consisted predominantly of weakly metamorphic Paleozoic terrains (Greywacke Zone and equivalents) as well as the Late Carboniferous to Scythian siliciclastic base of the NCA to the south of the depositional area. To the west, the Augenstein Formation interfingered with the Tertiary deposits of the Inntal. Sedimentation of the Augenstein Formation was terminated in Early Miocene time in the course of the orogenic collapse of the Eastern Alps. The Augenstein sediments were eroded and redeposited in the foreland Molasse zone. From Pannonian times (~10 Ma) on, the NCA and the denuded Dachstein surface experienced uplift in several pulses. The Dachstein Paleosurface has been preserved in areas, in which thick limestone sequences allowed subsurface erosion by cave formation and thus prevented major surface erosion.
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the dachstein Paleosurface and the augenstein formation in the northern calcareous alps a mosaic stone in the geomorphological evolution of the eastern alps
International Journal of Earth Sciences, 2001Co-Authors: Wolfgang Frisch, Joachim Kuhlemann, István Dunkl, Balázs SzékelyAbstract:The central and eastern areas of the Northern Calcareous Alps (NCA) are characterized by remnants of the Dachstein Paleosurface, which formed in Late Eocene (?) to Early Oligocene time and is preserved with limited modification on elevated karst plateaus. In Oligocene time, the Dachstein Paleosurface subsided and was sealed by the Augenstein Formation, a terrestrial succession of conglomerates and sandstones, which are only preserved in small remnants on the plateaus, some in an autochthonous position. Thermochronological data suggest a maximum thickness of the Augenstein Formation of >1.3 km, possibly >2 km. The age of the Augenstein Formation is constrained by the overall geological situation as Early Oligocene to earliest Miocene. Fission track age data support an Early Oligocene age of the basal parts of the formation. The source area of the Augenstein Formation consisted predominantly of weakly metamorphic Paleozoic terrains (Greywacke Zone and equivalents) as well as the Late Carboniferous to Scythian siliciclastic base of the NCA to the south of the depositional area. To the west, the Augenstein Formation interfingered with the Tertiary deposits of the Inntal. Sedimentation of the Augenstein Formation was terminated in Early Miocene time in the course of the orogenic collapse of the Eastern Alps. The Augenstein sediments were eroded and redeposited in the foreland Molasse zone. From Pannonian times (~10 Ma) on, the NCA and the denuded Dachstein surface experienced uplift in several pulses. The Dachstein Paleosurface has been preserved in areas, in which thick limestone sequences allowed subsurface erosion by cave formation and thus prevented major surface erosion.