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Rob Westaway - One of the best experts on this subject based on the ideXlab platform.
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River Terrace development in the NE Mediterranean region (Syria and Turkey): Patterns in relation to crustal type
Quaternary Science Reviews, 2017Co-Authors: David R. Bridgland, Tuncer Demir, Ali Seyrek, Mohamad Daoud, Mohammad Abou Romieh, Rob WestawayAbstract:It is widely recognized that the optimal development of River Terraces globally has been in the temperate latitudes, with NW and Central Europe being areas of particular importance for the preservation of such archives of Quaternary environmental change. There is also a growing consensus that the principal dRivers of Terrace formation have been climatic fluctuation against a background of progressive (but variable) uplift. Nonetheless River Terraces are widely preserved in the Mediterranean region, where they have often been attributed to the effects of neotectonic activity, with a continuing debate about the relative significance of fluctuating temperature (glacials–interglacials) and precipitation (pluvials–interpluvials). Research in Syria and southern–central Turkey (specifically in the valleys of the Tigris and Ceyhan in Turkey, the Kebir in Syria and the trans-border Rivers Orontes and Euphrates) has underlined the importance of uplift rates in dictating the preservation pattern of fluvial archives and has revealed different patterns that can be related to crustal type. The NE Mediterranean coastal region has experienced unusually rapid uplift in the Late Quaternary. The relation between the Kebir Terraces and the staircase of interglacial raised beaches preserved along the Mediterranean coastline of NW Syria reinforces previous conclusions that the emplacement of the fluvial Terrace deposits in the Mediterranean has occurred during colder climatic episodes.
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The use of fluvial archives in reconstructing landscape evolution: the value of sedimentary and morphostratigraphical evidence
Netherlands Journal of Geosciences - Geologie en Mijnbouw, 2012Co-Authors: David R. Bridgland, Rob WestawayAbstract:AbstractEvidence-based interpretations of fluvial evolution, and especially of River-Terrace formation, have advanced significantly in recent decades, with a notable contribution made by activities of the Fluvial Archives Group. Well-dated River-Terrace sequences provide frameworks for the understanding of landscape evolution, since they record valley-floor levels that were higher in the past, attributable, from their patterns of occurrence, to regional uplift. The role of climate fluctuation during the Quaternary is also paramount, since this has been an important dRiver of the varied fluvial activity that has given rise to the staircases of Terraces that characterise the temperate latitudes. This approach is contrasted with a more theoretical methodology for using Rivers as recorders of landscape evolution, again with an emphasis on uplift, based on the concept of the formation of knickpoints at particular base levels and their migration upstream. Although different timescales can be explored by the two methods, the concept of headward-migrating knickpoints implies a mechanism for incision that is difficult to reconcile with the formation of the broadly parallel River Terraces that are observed in many systems. Knickpoints can frequently be observed to coincide with gorge reaches, where River valleys are constricted as a result of resistant bedrock and/or the effects of localised active crustal deformation. This raises the possibility that knickpoints have generally formed in response to factors of local geology rather than migrating from downstream.
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climatically controlled River Terrace staircases a worldwide quaternary phenomenon
Geomorphology, 2008Co-Authors: David R. Bridgland, Rob WestawayAbstract:A comparison of fluvial Terrace sequences from around the world, based on data collected as part of International Geoscience Programme (IGCP) Project No. 449, has revealed significant patterns. River Terraces provide important records of uplift, which is essential for their formation, and of landscape evolution. Their cyclic formation, however, almost invariably seems to have been a response to climatic fluctuation. Sequences in the European core area of IGCP 449, which has the longest and most extensive research history, have been used as templates for worldwide comparison. There is evidence for a global acceleration of uplift at the time of, and perhaps in response to, the Mid-Pleistocene Revolution, when climatic fluctuation switched to 100 kyr Milankovitch cycles. Terraces formed prior to this generally consist of wide aggradational sheets that probably each represent formation over several 41 kyr cycles. Subsequently, River valleys became more steeply entrenched and Terraces formed in response to the stronger 100 kyr climatic forcing, in many cases at approximately one per cycle. This paper uses the new data resource to explore differences between records in different climate zones, between sequences with variable numbers of Middle–Late Pleistocene Terraces and between systems in which the all-important incision event has occurred in different parts of climatic cycles. Key records discussed include European examples from the Rhine, Thames, Somme, Dniester, Dnieper, Don, Volga and Aguas; from Asia the Gediz (Turkey) and Orontes (Syria); from North America, the South Platte and Colorado; from South Africa the Vaal and Sundays; from Australia the Shoalhaven; and from South America, the Amazon, Paraguay and tributaries of the Colorado and Negro.
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An obliquity-controlled Early Pleistocene River Terrace record from Western Turkey?
Quaternary Research, 2005Co-Authors: Darrel Maddy, David R. Bridgland, A. Veldkamp, Tuncer Demir, C. Stemerdink, Tim Van Der Schriek, Rob WestawayAbstract:Investigation of the Pleistocene sequence of the Gediz River, Western Turkey, has revealed a record of Early Pleistocene River Terraces. Eleven Terraces spanning the interval from 1.67 to 1.245 million years ago (MIS 59–37) are preserved beneath basaltic lava flows. The high number of Terraces over this short time period reflects high-frequency sedimentation/incision cycles preserved due to the fortuitous combination of relatively high uplift rates (∼0.16 mm yr−1) and progressive southwards valley migration. Comparison of this record with ODP967 from the Eastern Mediterranean Basin suggests a link between the production of Terraces and obliquity-driven ∼41,000 year climate cycles in the Early Pleistocene.
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pliocene and quaternary regional uplift in western turkey the gediz River Terrace staircase and the volcanism at kula
Tectonophysics, 2004Co-Authors: Rob Westaway, David R. Bridgland, Tuncer Demir, Malcolm S Pringle, Sema Yurtmen, George Rowbotham, D MaddyAbstract:Abstract Along the upper reaches of the Gediz River in western Turkey, in the eastern part of the Aegean extensional province, the land surface has uplifted by ∼400 m since the Middle Pliocene. This uplift is revealed by progressive gorge incision, and its rate can be established because River Terraces are capped by basalt flows that have been K–Ar and Ar–Ar dated. At present, the local uplift rate is ∼0.2 mm a−1. Uplift at this rate began around the start of the Middle Pleistocene, following a span of time when the uplift was much slower. This was itself preceded by an earlier uplift phase, apparently in the late Late Pliocene and early Early Pleistocene, when the uplift rate was comparable to the present. The resulting regional uplift history resembles what is observed in other regions and is analogously interpreted as the isostatic response to changing rates of surface processes linked to global environmental change. We suggest that this present phase of surface uplift, amounting so far to ∼150 m, is being caused by the nonsteady-state thermal and isostatic response of the crust to erosion, following an increase in erosion rates in the late Early Pleistocene, most likely as a result of the first large northern-hemisphere glaciation during oxygen isotope stage 22 at 870 ka. We suggest that the earlier uplift phase, responsible for the initial ∼250 m of uplift, resulted from a similar increase in erosion rates caused by the deterioration in local climate at ∼3.1 Ma. This uplift thus has no direct relationship to the crustal extension occurring in western Turkey, the rate and sense of which are thought not to have changed significantly on this time scale. Our results thus suggest that the present, often deeply incised, landscape of western Turkey has largely developed from the Middle Pleistocene onwards, for reasons not directly related to the active normal faulting that is also occurring. The local isostatic consequences of this active faulting are instead superimposed onto this “background” of regional surface uplift. Modelling of this surface uplift indicates that the effective viscosity of the lower continental crust beneath this part of Turkey is of the order of ∼1019 Pa s, similar to a recent estimate for beneath central Greece. The lower uplift rates observed in western Turkey, compared with central Greece, result from the longer typical distances of fluvial sediment transport, which cause weaker coupling by lower-crustal flow between offshore depocentres and eroding onshore regions that provide the sediment source.
David R. Bridgland - One of the best experts on this subject based on the ideXlab platform.
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River Terrace development in the NE Mediterranean region (Syria and Turkey): Patterns in relation to crustal type
Quaternary Science Reviews, 2017Co-Authors: David R. Bridgland, Tuncer Demir, Ali Seyrek, Mohamad Daoud, Mohammad Abou Romieh, Rob WestawayAbstract:It is widely recognized that the optimal development of River Terraces globally has been in the temperate latitudes, with NW and Central Europe being areas of particular importance for the preservation of such archives of Quaternary environmental change. There is also a growing consensus that the principal dRivers of Terrace formation have been climatic fluctuation against a background of progressive (but variable) uplift. Nonetheless River Terraces are widely preserved in the Mediterranean region, where they have often been attributed to the effects of neotectonic activity, with a continuing debate about the relative significance of fluctuating temperature (glacials–interglacials) and precipitation (pluvials–interpluvials). Research in Syria and southern–central Turkey (specifically in the valleys of the Tigris and Ceyhan in Turkey, the Kebir in Syria and the trans-border Rivers Orontes and Euphrates) has underlined the importance of uplift rates in dictating the preservation pattern of fluvial archives and has revealed different patterns that can be related to crustal type. The NE Mediterranean coastal region has experienced unusually rapid uplift in the Late Quaternary. The relation between the Kebir Terraces and the staircase of interglacial raised beaches preserved along the Mediterranean coastline of NW Syria reinforces previous conclusions that the emplacement of the fluvial Terrace deposits in the Mediterranean has occurred during colder climatic episodes.
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John Lubbock's early contribution to the understanding of River Terraces and their importance to Geography, Archaeology and Earth Science
Notes and Records: the Royal Society Journal of the History of Science, 2013Co-Authors: David R. BridglandAbstract:In his writings John Lubbock expounded views on the understanding of past climates, prehistoric faunas, early humans, and the evolution of landscape and River systems. His contributions on some of these related topics are scarcely remembered, despite comparison with modern thinking showing them frequently to have been prescient. He visited the Somme valley, observing River Terrace gravels and Palaeolithic artefacts in the company of the leading geologists and archaeologists of his day, visits that furnished knowledge of the early archaeological record and were also formative in terms of his understanding of River-valley and landscape evolution. He noted that Terraces represented former valley-floor levels and that Rivers had deepened their valleys in response to uplift of the land, something that is often not fully grasped at the present time. He was also an early believer in interglacial–glacial climatic fluctuation, an idea not widely accepted in Britain until after his death.
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The use of fluvial archives in reconstructing landscape evolution: the value of sedimentary and morphostratigraphical evidence
Netherlands Journal of Geosciences - Geologie en Mijnbouw, 2012Co-Authors: David R. Bridgland, Rob WestawayAbstract:AbstractEvidence-based interpretations of fluvial evolution, and especially of River-Terrace formation, have advanced significantly in recent decades, with a notable contribution made by activities of the Fluvial Archives Group. Well-dated River-Terrace sequences provide frameworks for the understanding of landscape evolution, since they record valley-floor levels that were higher in the past, attributable, from their patterns of occurrence, to regional uplift. The role of climate fluctuation during the Quaternary is also paramount, since this has been an important dRiver of the varied fluvial activity that has given rise to the staircases of Terraces that characterise the temperate latitudes. This approach is contrasted with a more theoretical methodology for using Rivers as recorders of landscape evolution, again with an emphasis on uplift, based on the concept of the formation of knickpoints at particular base levels and their migration upstream. Although different timescales can be explored by the two methods, the concept of headward-migrating knickpoints implies a mechanism for incision that is difficult to reconcile with the formation of the broadly parallel River Terraces that are observed in many systems. Knickpoints can frequently be observed to coincide with gorge reaches, where River valleys are constricted as a result of resistant bedrock and/or the effects of localised active crustal deformation. This raises the possibility that knickpoints have generally formed in response to factors of local geology rather than migrating from downstream.
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climatically controlled River Terrace staircases a worldwide quaternary phenomenon
Geomorphology, 2008Co-Authors: David R. Bridgland, Rob WestawayAbstract:A comparison of fluvial Terrace sequences from around the world, based on data collected as part of International Geoscience Programme (IGCP) Project No. 449, has revealed significant patterns. River Terraces provide important records of uplift, which is essential for their formation, and of landscape evolution. Their cyclic formation, however, almost invariably seems to have been a response to climatic fluctuation. Sequences in the European core area of IGCP 449, which has the longest and most extensive research history, have been used as templates for worldwide comparison. There is evidence for a global acceleration of uplift at the time of, and perhaps in response to, the Mid-Pleistocene Revolution, when climatic fluctuation switched to 100 kyr Milankovitch cycles. Terraces formed prior to this generally consist of wide aggradational sheets that probably each represent formation over several 41 kyr cycles. Subsequently, River valleys became more steeply entrenched and Terraces formed in response to the stronger 100 kyr climatic forcing, in many cases at approximately one per cycle. This paper uses the new data resource to explore differences between records in different climate zones, between sequences with variable numbers of Middle–Late Pleistocene Terraces and between systems in which the all-important incision event has occurred in different parts of climatic cycles. Key records discussed include European examples from the Rhine, Thames, Somme, Dniester, Dnieper, Don, Volga and Aguas; from Asia the Gediz (Turkey) and Orontes (Syria); from North America, the South Platte and Colorado; from South Africa the Vaal and Sundays; from Australia the Shoalhaven; and from South America, the Amazon, Paraguay and tributaries of the Colorado and Negro.
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An obliquity-controlled Early Pleistocene River Terrace record from Western Turkey?
Quaternary Research, 2005Co-Authors: Darrel Maddy, David R. Bridgland, A. Veldkamp, Tuncer Demir, C. Stemerdink, Tim Van Der Schriek, Rob WestawayAbstract:Investigation of the Pleistocene sequence of the Gediz River, Western Turkey, has revealed a record of Early Pleistocene River Terraces. Eleven Terraces spanning the interval from 1.67 to 1.245 million years ago (MIS 59–37) are preserved beneath basaltic lava flows. The high number of Terraces over this short time period reflects high-frequency sedimentation/incision cycles preserved due to the fortuitous combination of relatively high uplift rates (∼0.16 mm yr−1) and progressive southwards valley migration. Comparison of this record with ODP967 from the Eastern Mediterranean Basin suggests a link between the production of Terraces and obliquity-driven ∼41,000 year climate cycles in the Early Pleistocene.
D Maddy - One of the best experts on this subject based on the ideXlab platform.
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pliocene and quaternary regional uplift in western turkey the gediz River Terrace staircase and the volcanism at kula
Tectonophysics, 2004Co-Authors: Rob Westaway, David R. Bridgland, Tuncer Demir, Malcolm S Pringle, Sema Yurtmen, George Rowbotham, D MaddyAbstract:Abstract Along the upper reaches of the Gediz River in western Turkey, in the eastern part of the Aegean extensional province, the land surface has uplifted by ∼400 m since the Middle Pliocene. This uplift is revealed by progressive gorge incision, and its rate can be established because River Terraces are capped by basalt flows that have been K–Ar and Ar–Ar dated. At present, the local uplift rate is ∼0.2 mm a−1. Uplift at this rate began around the start of the Middle Pleistocene, following a span of time when the uplift was much slower. This was itself preceded by an earlier uplift phase, apparently in the late Late Pliocene and early Early Pleistocene, when the uplift rate was comparable to the present. The resulting regional uplift history resembles what is observed in other regions and is analogously interpreted as the isostatic response to changing rates of surface processes linked to global environmental change. We suggest that this present phase of surface uplift, amounting so far to ∼150 m, is being caused by the nonsteady-state thermal and isostatic response of the crust to erosion, following an increase in erosion rates in the late Early Pleistocene, most likely as a result of the first large northern-hemisphere glaciation during oxygen isotope stage 22 at 870 ka. We suggest that the earlier uplift phase, responsible for the initial ∼250 m of uplift, resulted from a similar increase in erosion rates caused by the deterioration in local climate at ∼3.1 Ma. This uplift thus has no direct relationship to the crustal extension occurring in western Turkey, the rate and sense of which are thought not to have changed significantly on this time scale. Our results thus suggest that the present, often deeply incised, landscape of western Turkey has largely developed from the Middle Pleistocene onwards, for reasons not directly related to the active normal faulting that is also occurring. The local isostatic consequences of this active faulting are instead superimposed onto this “background” of regional surface uplift. Modelling of this surface uplift indicates that the effective viscosity of the lower continental crust beneath this part of Turkey is of the order of ∼1019 Pa s, similar to a recent estimate for beneath central Greece. The lower uplift rates observed in western Turkey, compared with central Greece, result from the longer typical distances of fluvial sediment transport, which cause weaker coupling by lower-crustal flow between offshore depocentres and eroding onshore regions that provide the sediment source.
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River Terrace sequences templates for quaternary geochronology and marine terrestrial correlation
Journal of Quaternary Science, 2004Co-Authors: David R. Bridgland, D Maddy, Martin BatesAbstract:Fluvial sequences, particularly Terrace staircases, represent archives of Quaternary palaeoclimatic fluctuation and can serve as stratigraphical frameworks for geochronology and for correlation with other depositional environments, in particular, the global marine oxygen isotope record. Fluvial lithostratigraphical frameworks also provide contexts for records, from fossils and artefacts, of faunal evolution and human occupation; conversely, both records can be means of relative dating of Riverine sequences. Three fluvial sequences are examined as case studies. First is the Severn-Avon system in the English Midlands, which has biostratgraphical evidence and an amino acid geochronology, together with marker inputs from three different glaciations. The Somme sequence of northern France, famous for its Palaeolithic artefact assemblages, again has biostratigraphy and an amino acid geochronology and has also been dated with reference to overlying loess/palaeosols sequences. The fluvial Terraces of the River Arun, the final case study, lack dating evidence but are interspersed within the Sussex raised beach staircase. Although various lines of evidence suggest that the Rivers discussed have formed Terraces in response to climatic fluctuation, an intriguing difference is that interglacial sediments occur at the bases of Terrace formations in the Severn-Avon, whereas in the Somme they occur at the tops of sequences, beneath loessic overburden.
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pliocene and quaternary surface uplift of western turkey revealed by long term River Terrace sequences
Current Science, 2003Co-Authors: Rob Westaway, David R. Bridgland, Tuncer Demir, Malcolm S Pringle, Sema Yurtmen, George Rowbotham, D MaddyAbstract:Western Turkey forms the eastern part of the Aegean extensional province. In the 1980s it was accepted that vertical crustal motions in this region are caused solely by this active normal faulting, with footwall localities uplifting and hanging-walls subsiding. The presence of marine sediments, interpreted as Pliocene, at altitudes in excess of 400 m in some hanging-wall localities provided - in the late 1980s - the first clear evidence of Pliocene-Quaternary regional surface uplift. However, it has since been argued that the incision of River gorges in this region has been caused instead by localized uplift in normal-fault footwalls. We review the available geomorphological and sedimentary evidence from the Denizli area, within the drainage catchment of the Buyuk Menderes River, in support of ~ 400 m of Plio- Quaternary regional surface uplift. We also examine the staircase of four high Terraces, formed of cemented fluvial gravel at ~ 360, ~ 330, ~ 255, and ~ 225 m above River level, is identified. Farther downstream, a similar Terrace, ~ 200 m above this River and so tentatively correlated with the ~ 225 m Terrace upstream, was also identified within the Quaternary volcanic field around Kula. Nearby, a slightly lower (~ 190 m) Terrace gravel is capped by basalt, K-Ar dated to ~ 1.2 Ma; below this, other similar Terraces form a lower-level staircase. We interpret this evidence as indicating uplift rates of ~ 0.1 mm a -1 or more in the latest Pliocene, when the staircase of cemented high Terraces appears to have formed, relative stability for much of the Early Pleis- tocene, but renewed uplift at rates approaching ~ 0.2 mm a -1 in the Middle and Late Pleistocene. The resulting uplift history resembles what is observed in other regions, and has been modelled as the isostatic response to changing rates of surface processes linked to global environmental change, with no direct rela- tionship to the crustal extension occurring in western Turkey. Our results thus suggest that the present, often deeply-incised, landscape of western Turkey has largely developed from the Middle Pleistocene onwards, for reasons not directly related to the active normal faulting, the local isostatic consequences of which are superimposed onto this 'background' of regional surface uplift.
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uplift driven valley incision and climate controlled River Terrace development in the thames valley uk
Quaternary International, 2001Co-Authors: D Maddy, David R. Bridgland, Rob WestawayAbstract:Abstract The sequence of Terraces of the River Thames in southeast England has previously been shown to span the period from the earliest Pleistocene to the present. This Terrace sequence contains biostratigraphical and sedimentary evidence that testifies to the high-amplitude climatic changes of the Quaternary. Large-scale fluvial incision, resulting in basin-wide Terrace formation, appears to have been concentrated at the warming limbs of the major climatic glacial–interglacial cycles, when sediment supply was greatly reduced. This incision and subsequent valley-floor widening created the accommodation space for the later aggradation of the Terrace sediments during the following warm–cold transitions and during the cold stages, when high-sediment supply conditions prevailed. Although the timing of Terrace aggradation may be controlled by climate change, the progressive valley incision recorded by Terrace staircases cannot easily be explained in terms of Quaternary climatic change alone and recently developed models suggest that long-term incision by the Thames has been driven by uplift. This paper presents an overview of the available Terrace data and tabulates incision amounts and rates between key stratigraphic horizons. Superimposed upon these broad changes, revealed by the complex internal sedimentary architecture of many Terrace sediments, are the geomorphological system responses to both higher-frequency climate-driven changes and more localized intrinsic fluvial system adjustments.
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uplift driven valley incision and River Terrace formation in southern england
Journal of Quaternary Science, 1997Co-Authors: D MaddyAbstract:Outside the limits of Middle Pleistocene glaciation, the River basins of Southern England contain long Cenozoic terrestrial sedimentary records. Of greatest importance are the River Terrace sequences, which contain biostratigraphical and sedimentary evidence that testifies to the high-amplitude climatic changes of the Quaternary. However, trends in valley development cannot easily be accommodated within the framework of Quaternary climatic change. It is argued in this paper that episodic incision and Terrace development result from uplift, a consequence of the interplay between continuing Alpine orogenic movements and erosion-driven isostasy. Using a simple linear model (height–age) an uplift rate of ca. 7 cm ka−1 is estimated for the Terrace sequence in the upper Thames valley. This preliminary model is evaluated using the records of adjacent basins. © 1997 John Wiley & Sons, Ltd.
Darrel Maddy - One of the best experts on this subject based on the ideXlab platform.
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Field mapping and GIS visualisation of Quaternary River Terrace landforms: an example from the Río Almanzora, SE Spain
Journal of Maps, 2010Co-Authors: Chris Meikle, Martin Stokes, Darrel MaddyAbstract:Abstract Please click here to download the map associated with this article. This paper presents the mapping results of a Quaternary River Terrace staircase associated with the evolution of the Rio Almanzora in SE Spain. Prior to map compilation a formal landform stratigraphy was constructed from remote sensing and field reconnaissance using standard allostratigraphic procedures as outlined by the North American Stratigraphic Commission. The stratigraphic framework comprised five allomembers of the Rio Almanzora Alloformation corresponding to an inset sequence of River Terrace levels that document > 150 m of Quaternary fluvial incision by the Rio Almanzora. The Terrace stratigraphy was mapped in the field using a hand held GPS to construct control points that tracked breaks and changes in slope associated with Terrace stratigraphic boundaries. The field map and survey data were compiled in a GIS geodatabase and overlaid onto a DEM and geological map data for analysis and visualisation purposes. The strati...
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An obliquity-controlled Early Pleistocene River Terrace record from Western Turkey?
Quaternary Research, 2005Co-Authors: Darrel Maddy, David R. Bridgland, A. Veldkamp, Tuncer Demir, C. Stemerdink, Tim Van Der Schriek, Rob WestawayAbstract:Investigation of the Pleistocene sequence of the Gediz River, Western Turkey, has revealed a record of Early Pleistocene River Terraces. Eleven Terraces spanning the interval from 1.67 to 1.245 million years ago (MIS 59–37) are preserved beneath basaltic lava flows. The high number of Terraces over this short time period reflects high-frequency sedimentation/incision cycles preserved due to the fortuitous combination of relatively high uplift rates (∼0.16 mm yr−1) and progressive southwards valley migration. Comparison of this record with ODP967 from the Eastern Mediterranean Basin suggests a link between the production of Terraces and obliquity-driven ∼41,000 year climate cycles in the Early Pleistocene.
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River Terrace sequences : templates for quaternary geochronology and marine-terrestrial correlation.
Journal of Quaternary Science, 2004Co-Authors: David R. Bridgland, Darrel Maddy, Martin BatesAbstract:Fluvial sequences, particularly Terrace staircases, represent archives of Quaternary palaeoclimatic fluctuation and can serve as stratigraphical frameworks for geochronology and for correlation with other depositional environments, in particular, the global marine oxygen isotope record. Fluvial lithostratigraphical frameworks also provide contexts for records, from fossils and artefacts, of faunal evolution and human occupation; conversely, both records can be means of relative dating of Riverine sequences. Three fluvial sequences are examined as case studies. First is the Severn–Avon system in the English Midlands, which has biostratgraphical evidence and an amino acid geochronology, together with marker inputs from three different glaciations. The Somme sequence of northern France, famous for its Palaeolithic artefact assemblages, again has biostratigraphy and an amino acid geochronology and has also been dated with reference to overlying loess/palaeosols sequences. The fluvial Terraces of the River Arun, the final case study, lack dating evidence but are interspersed within the Sussex raised beach staircase. Although various lines of evidence suggest that the Rivers discussed have formed Terraces in response to climatic fluctuation, an intriguing difference is that interglacial sediments occur at the bases of Terrace formations in the Severn–Avon, whereas in the Somme they occur at the tops of sequences, beneath loessic overburden. Copyright © 2004 John Wiley & Sons, Ltd.
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Crustal uplift in southern England: evidence from the River Terrace records
Geomorphology, 2000Co-Authors: Darrel Maddy, David R. Bridgland, C.p. GreenAbstract:Abstract Much of the past work on the Quaternary Rivers of northwest Europe has been concerned with River Terraces, which characterise almost every valley. While these Terraces are undoubtedly striking features of the landscape, the incision achieved by Quaternary Rivers is equally significant in terms of River behaviour, and for an understanding of the factors affecting landform development during the Quaternary. This paper examines the incision achieved during the Quaternary by the Thames, in both its upper and lower catchments, and by the Hampshire Avon in southern England. Valley incision rates of ca. 0.07–0.10 m ka −1 have been identified, although in the lower catchment of the Thames, these have been enhanced by additional incision in response to glacio-isostasy and valley shortening. A model is proposed in which regional uplift is recognized as the primary cause of incision by these Quaternary Rivers. Possible mechanisms for regional uplift are considered.
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Uplift‐driven valley incision and River Terrace formation in southern England
Journal of Quaternary Science, 1997Co-Authors: Darrel MaddyAbstract:Outside the limits of Middle Pleistocene glaciation, the River basins of Southern England contain long Cenozoic terrestrial sedimentary records. Of greatest importance are the River Terrace sequences, which contain biostratigraphical and sedimentary evidence that testifies to the high-amplitude climatic changes of the Quaternary. However, trends in valley development cannot easily be accommodated within the framework of Quaternary climatic change. It is argued in this paper that episodic incision and Terrace development result from uplift, a consequence of the interplay between continuing Alpine orogenic movements and erosion-driven isostasy. Using a simple linear model (height–age) an uplift rate of ca. 7 cm ka−1 is estimated for the Terrace sequence in the upper Thames valley. This preliminary model is evaluated using the records of adjacent basins. © 1997 John Wiley & Sons, Ltd.
Tuncer Demir - One of the best experts on this subject based on the ideXlab platform.
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River Terrace development in the NE Mediterranean region (Syria and Turkey): Patterns in relation to crustal type
Quaternary Science Reviews, 2017Co-Authors: David R. Bridgland, Tuncer Demir, Ali Seyrek, Mohamad Daoud, Mohammad Abou Romieh, Rob WestawayAbstract:It is widely recognized that the optimal development of River Terraces globally has been in the temperate latitudes, with NW and Central Europe being areas of particular importance for the preservation of such archives of Quaternary environmental change. There is also a growing consensus that the principal dRivers of Terrace formation have been climatic fluctuation against a background of progressive (but variable) uplift. Nonetheless River Terraces are widely preserved in the Mediterranean region, where they have often been attributed to the effects of neotectonic activity, with a continuing debate about the relative significance of fluctuating temperature (glacials–interglacials) and precipitation (pluvials–interpluvials). Research in Syria and southern–central Turkey (specifically in the valleys of the Tigris and Ceyhan in Turkey, the Kebir in Syria and the trans-border Rivers Orontes and Euphrates) has underlined the importance of uplift rates in dictating the preservation pattern of fluvial archives and has revealed different patterns that can be related to crustal type. The NE Mediterranean coastal region has experienced unusually rapid uplift in the Late Quaternary. The relation between the Kebir Terraces and the staircase of interglacial raised beaches preserved along the Mediterranean coastline of NW Syria reinforces previous conclusions that the emplacement of the fluvial Terrace deposits in the Mediterranean has occurred during colder climatic episodes.
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An obliquity-controlled Early Pleistocene River Terrace record from Western Turkey?
Quaternary Research, 2005Co-Authors: Darrel Maddy, David R. Bridgland, A. Veldkamp, Tuncer Demir, C. Stemerdink, Tim Van Der Schriek, Rob WestawayAbstract:Investigation of the Pleistocene sequence of the Gediz River, Western Turkey, has revealed a record of Early Pleistocene River Terraces. Eleven Terraces spanning the interval from 1.67 to 1.245 million years ago (MIS 59–37) are preserved beneath basaltic lava flows. The high number of Terraces over this short time period reflects high-frequency sedimentation/incision cycles preserved due to the fortuitous combination of relatively high uplift rates (∼0.16 mm yr−1) and progressive southwards valley migration. Comparison of this record with ODP967 from the Eastern Mediterranean Basin suggests a link between the production of Terraces and obliquity-driven ∼41,000 year climate cycles in the Early Pleistocene.
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pliocene and quaternary regional uplift in western turkey the gediz River Terrace staircase and the volcanism at kula
Tectonophysics, 2004Co-Authors: Rob Westaway, David R. Bridgland, Tuncer Demir, Malcolm S Pringle, Sema Yurtmen, George Rowbotham, D MaddyAbstract:Abstract Along the upper reaches of the Gediz River in western Turkey, in the eastern part of the Aegean extensional province, the land surface has uplifted by ∼400 m since the Middle Pliocene. This uplift is revealed by progressive gorge incision, and its rate can be established because River Terraces are capped by basalt flows that have been K–Ar and Ar–Ar dated. At present, the local uplift rate is ∼0.2 mm a−1. Uplift at this rate began around the start of the Middle Pleistocene, following a span of time when the uplift was much slower. This was itself preceded by an earlier uplift phase, apparently in the late Late Pliocene and early Early Pleistocene, when the uplift rate was comparable to the present. The resulting regional uplift history resembles what is observed in other regions and is analogously interpreted as the isostatic response to changing rates of surface processes linked to global environmental change. We suggest that this present phase of surface uplift, amounting so far to ∼150 m, is being caused by the nonsteady-state thermal and isostatic response of the crust to erosion, following an increase in erosion rates in the late Early Pleistocene, most likely as a result of the first large northern-hemisphere glaciation during oxygen isotope stage 22 at 870 ka. We suggest that the earlier uplift phase, responsible for the initial ∼250 m of uplift, resulted from a similar increase in erosion rates caused by the deterioration in local climate at ∼3.1 Ma. This uplift thus has no direct relationship to the crustal extension occurring in western Turkey, the rate and sense of which are thought not to have changed significantly on this time scale. Our results thus suggest that the present, often deeply incised, landscape of western Turkey has largely developed from the Middle Pleistocene onwards, for reasons not directly related to the active normal faulting that is also occurring. The local isostatic consequences of this active faulting are instead superimposed onto this “background” of regional surface uplift. Modelling of this surface uplift indicates that the effective viscosity of the lower continental crust beneath this part of Turkey is of the order of ∼1019 Pa s, similar to a recent estimate for beneath central Greece. The lower uplift rates observed in western Turkey, compared with central Greece, result from the longer typical distances of fluvial sediment transport, which cause weaker coupling by lower-crustal flow between offshore depocentres and eroding onshore regions that provide the sediment source.
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River Terrace sequences in Turkey: sources of evidence for lateral variations in regional uplift
Proceedings of the Geologists' Association, 2004Co-Authors: Tuncer Demir, İrfan Yeşilnacar, Rob WestawayAbstract:This paper reviews River Terrace staircases in Turkey and examines their relation to regional uplift. Turkish fluvial records are shown to be similar to their counterparts in Europe, with aggradation concentrated in cold climatic stages, despite differences in present-day climate between these two regions. Furthermore, as in Europe, these Turkish River Terrace sequences provide evidence for increases in regional uplift rates in the Late Pliocene and Middle Pleistocene. In both regions, this effect is unrelated to senses and rates of plate motion, being instead the result of crustal thickening caused by lower-crustal flow induced by surface processes. From the fluvial evidence, estimated amounts of regional uplift since the Miocene are typically c . 400 m in western Turkey and in the area of the border with Syria. However, they increase northward and eastward to c . 1 km or more in northeastern Turkey on this time-scale, reflecting the regional variations in mean altitude of the land surface. Estimated typical uplift rates during the Middle and Late Pleistocene have been c . 0.1 mm a −1 in the Arabian Platform and c . 0.2–0.3 mm a −1 in western and northern Turkey. These variations are interpreted as the isostatic response to lateral variations in erosion rates.
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pliocene and quaternary surface uplift of western turkey revealed by long term River Terrace sequences
Current Science, 2003Co-Authors: Rob Westaway, David R. Bridgland, Tuncer Demir, Malcolm S Pringle, Sema Yurtmen, George Rowbotham, D MaddyAbstract:Western Turkey forms the eastern part of the Aegean extensional province. In the 1980s it was accepted that vertical crustal motions in this region are caused solely by this active normal faulting, with footwall localities uplifting and hanging-walls subsiding. The presence of marine sediments, interpreted as Pliocene, at altitudes in excess of 400 m in some hanging-wall localities provided - in the late 1980s - the first clear evidence of Pliocene-Quaternary regional surface uplift. However, it has since been argued that the incision of River gorges in this region has been caused instead by localized uplift in normal-fault footwalls. We review the available geomorphological and sedimentary evidence from the Denizli area, within the drainage catchment of the Buyuk Menderes River, in support of ~ 400 m of Plio- Quaternary regional surface uplift. We also examine the staircase of four high Terraces, formed of cemented fluvial gravel at ~ 360, ~ 330, ~ 255, and ~ 225 m above River level, is identified. Farther downstream, a similar Terrace, ~ 200 m above this River and so tentatively correlated with the ~ 225 m Terrace upstream, was also identified within the Quaternary volcanic field around Kula. Nearby, a slightly lower (~ 190 m) Terrace gravel is capped by basalt, K-Ar dated to ~ 1.2 Ma; below this, other similar Terraces form a lower-level staircase. We interpret this evidence as indicating uplift rates of ~ 0.1 mm a -1 or more in the latest Pliocene, when the staircase of cemented high Terraces appears to have formed, relative stability for much of the Early Pleis- tocene, but renewed uplift at rates approaching ~ 0.2 mm a -1 in the Middle and Late Pleistocene. The resulting uplift history resembles what is observed in other regions, and has been modelled as the isostatic response to changing rates of surface processes linked to global environmental change, with no direct rela- tionship to the crustal extension occurring in western Turkey. Our results thus suggest that the present, often deeply-incised, landscape of western Turkey has largely developed from the Middle Pleistocene onwards, for reasons not directly related to the active normal faulting, the local isostatic consequences of which are superimposed onto this 'background' of regional surface uplift.
