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The study of alluvial terraces helps in reconstructing the past geometries of rivers and makes it possible to assess the rate and pattern of fluvial incision and bedrock uplift. The fluctuations of river base levels are particularly variable and complex during the Late Quaternary in the lower course of rivers due to the interplay of responses to sea‐level fluctuations, tectonics and glacio‐isostasy. In this paper, the geometry and chronology of Manoir Brésil, an outcrop of alluvial terraces of the Lower Seine River, northern France, are investigated through a multidisciplinary study. Fluvial incision during MIS 8 in the Lower Seine in relation to sea‐level drop is recorded by an erosional surface cut into the chalk bedrock. This surface is covered by MIS 7 tidal deposits and then by younger, mostly periglacial colluvium (head). Manoir Brésil is therefore considered to be a chronological equivalent of the nearby, well‐studied Tourville‐la‐Rivière outcrop. The deposits are affected by post‐MIS 7 cryoturbation processes. Based on the local elevation of MIS 7 tidal deposits and erosional surfaces at Manoir Brésil, a minimum bedrock uplift rate of 25–40 m/Ma and an erosion rate of 125 m/Ma during glacial periods can be proposed. A regional correlation of the MIS 8 erosional surface is increasingly deformed by uplift towards the North, making it difficult to correlate the fluvial deposits along the Seine without precise chronological control. We interpret this regional tilt as the result of isostasy rebound after glaciations, consistent with the distribution of the elevations of MIS 5e and MIS 7 marine deposits along the English Channel. [ABSTRACT FROM AUTHOR]

The Yellow River is usually assumed to record tectonic activities and climatic changes; however, a systematic study was lack in the sedimentology, stratigraphy, geomorphology and geochronology for the entire Yellow River though various geologic scholars have conducted numerous works in individual basins. This review focused on well-preserved fluvial terrace sequences that formed along this river on northeastern (NE) Tibetan Plateau and Ordos Block over the past 2.6 Ma. After comparing numerous initial incision ages at different segments along the Yellow River, we found out that the youngest initial incision may occur at ca. 150 ka at the Longyang Gorge. The Yellow River may transit from multiple separated endorheic drainages to an entire external drainage after 150 ka, which may cause differentiations in the apparent incision rates before and after 150 ka; thus apparent net incision rates were calculated respectively for the Yellow River before 150 ka and the drainage network post 150 ka. Apparent net incision rates prior to 0.15 Ma were calculated as 0.15, 0.29, 0.10, 0.12 and 0.03 mm/a respectively in Tongde-Xunhua, Lanzhou-Linxia basins, Heishan, Jinshan and Fenwei-Sanmen Gorges in this review, which mainly reflected Kunhuang-Gonghe Tectonic Event, generated by the Indo-Asian collision and diminishing as the NE Tibetan Plateau eastward extruding at ca. 1.8–0.15 Ma. Apparent net incision rates post 0.15 Ma were calculated respectively for NE Tibetan Plateau and Ordos Block, considering their different base level. On NE Tibetan Plateau, four fluvial degradational phases were identified between ca.105∼70, 53∼40, 25∼16 and 12∼6 ka associated with terrace levels respectively, at average elevations of 96, 40, 20 and 10.5 meters above the current river level (m arl) within a range of 5 ∼ 96 m arl; and four broad periods in the last 150 ka on Ordos Block: possibly marine oxygen isotope stage (MIS) 5, ca. 118 to 72 ka, most of MIS 3, ca. 44∼28 ka, transition from LGM to last deglacial ca. 20 to 16 ka, and 4∼3 ka at average elevations of 67.5, 26, 19 and 11.5 m arl. These degradational phases post 0.15 Ma were associated with multiple processes including enhanced fluvial discharge with an increase in monsoonal precipitation and/or melt water in deglaciation. [ABSTRACT FROM AUTHOR]

The forcing mechanism behind river incision and terrace formation is one of hot topics in the study of fluvial geomorphology. This work focused on the late Quaternary alluvial sequence in the south piedmont of the Chinese Altay Shan in the arid inland of Asia. In order to reveal the mechanism controlling the development of late Quaternary fluvial features along the mountain front, we conducted detailed fluvial geomorphological investigations on eight rivers, including geomorphic mapping, optically stimulated luminescence (OSL) dating, and differential global position system (dGPS) surveying. By utilizing the Monte Carlo simulation with terrace data, the late Quaternary rates of river incision along the south piedmont of the Chinese Altay Shan were determined. The results show that (1) the terraces developed by the piedmont rivers are not more than four levels and the depth of river incision in the piedmont is only dozens of meters, with deeper valleys displayed by the western piedmont rivers; (2) terrace alluviums along the mountain front were accumulated during glacial stages, and the subsequent incision occurred during interglacial stages; (3) the rate of river incision was accelerated during the Holocene, when the regional climate was characterized by progressively increasing wetness. When combining with the regional tectonic setting, we propose that the climate could have played the key role in driving the alluvial accumulation and the subsequent incision in the south piedmont of the Chinese Altay Shan during the late Quaternary. Together with the similar observations from the northeastern margin of the Tibetan Plateau and the Tian Shan, we further propose that climatically-driven fluvial geomorphological development could be a common phenomenon during the late Quaternary in the arid interior of Asia. • Alluvial sequences of the rivers in the south piedmont of the Chinese Altay Shan are classified. • Spatiotemporal patterns of river incision rates during the late Quaternary are characterized. • More river terrace levels and greater Holocene incision rates are observed in the west part of the piedmont. • Late Quaternary fluvial geomorphological development is attributed mainly to climate change. [ABSTRACT FROM AUTHOR]

Along the lower reaches of the Yarlung Zangbo River, scattered alluvium sections appear on T1 and T2 terraces. The alluvial deposits on the T1 terrace in Linduo and Ximogou and the T2 terrace in Guoguotang are composed principally of coarse-grained sand particles and rock fragments, with no observable fine-grained components. The T1 terrace alluvium section is dominated by clay and silt and occurs near the town of Dexing, and optically stimulated luminescence dating of sample from this site revealed an age of 18.2 kyear, which indicates that the incision rate of the Yarlung Zangbo River has been 4.7 mm/year since the formation of this section. On the basis of the component characteristics of terraces in Motuo County, the provenance for the terraces is probably related to the breaking of the palaeo-dammed lakes in the middle reaches of the Yarlung Zangbo River. A 430 m elevation difference still exists between the study area and the local base level downstream of the Yalung Zangbo River (Assam Plain), although this river has a strong incision capability (4.7 mm/year), which suggests that tectonic uplift remains very intense east of the Namche Barwa syntaxis.

The fluvial terraces along the banks of the Minjiang River are very important for understanding the tectonic activities of the eastern margin of the Tibetan Plateau and have been widely investigated. However, the reliability of the ages previously reported for the terraces needs further evaluation. In this study, the Minjiang River terraces in the Sonpan area from Hongqiaoguan to the Songpan town were investigated and dated using optically stimulated luminescence (OSL) techniques on quartz grains. Seven strath terraces (T1–T7) were recognized based on the exposures of fluvial sediment and the elevation of bedrock strath, and two of them have been reported by previous studies. The terrace deposits and overlying loess were sampled for OSL dating. The samples exhibited a large scatter in De, even for loess samples, which could be attributed to poor bleaching at deposition. However, the OSL ages obtained using the minimum age model were underestimated, and those obtained using the central age model are considered relatively reliable based on stratigraphic and geomorphological consistency and the comparison of the ages between stratigraphically parallel samples. The results show that the loess samples overlying fluvial terrace sediments were deposited later than terrace formation and their OSL ages cannot represent the terrace formation ages. The T1, T3, T4, T5, and T6 terraces were dated to 13.5 ± 0.6, 29.0 ± 1.7, 48.0 ± 3.3, 44.3 ± 5.2 and 63.8 ± 4.7 ka, respectively. The T4 and T5 terraces may be the same terrace with a weighted mean age of 46.9 ± 2.8 ka. The ages of the T2 and T7 terraces were inferred to be ∼20 and ∼80 ka, respectively, based on the relationship between strath ages and elevations of the other terraces. The mean bedrock river incision rates were calculated to be 1.2 ± 0.1 mm/a for the time period of 64 ka for the T6 terrace—14 ka for the T1 terrace, and 0.15 mm/a for the past 14 ka.

Landscape evolution is modulated by the regional tectonic uplift, climate change, and river dynamics. However, how to distinguish these mechanisms through the research of surface exhumation and fluvial incision remains controversial. In this study, cosmogenic 10Be, 26Al, and 21Ne concentrations in quartz from cave deposits, modern river sediments, and bedrocks were measured to constrain the applicability of cosmogenic 21Ne and discuss Quaternary landscape evolution history in the Guizhou Plateau, southeast China. Using the 26Al-10Be and 21Ne-10Be pairs to distinguish the cosmogenic 21Ne concentration from the excess 21Ne, we found that the nucleogenic 21Ne produced by the U and Th decay in quartz is significant in the samples although there is the possibility of inherited cosmogenic 21Ne. Combining with previous studies, we suggest that the precise approach for applying the cosmogenic 21Ne could be reached by (1) estimating the contribution from nucleogenic 21Ne, (2) avoiding samples with complex burial histories to exclude inherited cosmogenic 21Ne, and (3) combining the 10Be-26Al-21Ne nuclides method for the Quaternary samples. In addition, both pre-burial basin denudation rates and burial ages derived from the 26Al-10Be pair were used to determine the different timescale surface denudation rate and fluvial incision rate in relation to previous work. The consistency of the different timescales pre-burial basin denudation rate, 36Cl surface denudation rate, and modern basin denudation rate indicates that the landscape-scale surface denudation has been likely stabilized since the Quaternary in the Guizhou Plateau area. The slightly higher river incision rates than the local surface denudation rate show that the river dynamics may not have reached a steady-state due to the regional tectonic uplift in the Guizhou Plateau. [ABSTRACT FROM AUTHOR]

River incision and drainage reorganization have an important impact on the site selection of many major projects including city, road and others, and are the key issues of Quaternary environmental changes. Studies of river incision and river-network adjustment have traditionally been based on extensive field evidence, such as sediment age and beheaded river system. The Buyuan River basin is a large sub-basin of the upper Lancang-Mekong, with high mountains and extremely active erosion. The latter affects the preservation of the Quaternary period sediments leading to difficulties in understanding the main evolution characteristics of the basin. This study investigates differences in the equilibrium state of the longitudinal profile, infers incision rates, and evaluates drainage divide migration timelines using the stream-power incision model, the latest morphological dating, and Chi-plots (χ-z) based on digital elevation models (DEMs) on the GIS software platform. The final results show that two significant erosion base-level decreases occurred in the Late Pleistocene at least. The incision rate of the mainstream might have been 0–2.99 mm/yr since 100 ka BP and 0–3.28 mm/yr since 46 ka BP. The Chi-values across the divides suggest that space limited (or constrained) river reorganization and that there is no severe reorganization in the basin; the imbalance of traceable erosion only exists in local areas. The main driving force for the geomorphologic evolution of the Buyuan River basin is likely climate fluctuations rather than strong tectonic uplift since the Late Pleistocene. [ABSTRACT FROM AUTHOR]

Aiming at the rate and causes of the incision variations in the upper Himalaya Orogenic belt of Tibet, a new method of incision rate estimation based on the analysis of the evolution of Zhangmu landslide and its spatial and temporal relationship with the surrounding gullies is applied. The research results are: (1) The Zhangmu landslide was an ancient huge landslide, occurred at 24.2 ± 2.4 ka BP, consisting of an ancient bedrock landslide and subsequent deposit landslides, with an area of 1.23 km2, and remaining volume of 23.4 × 106 m3. (2) The fluvial incision rate shows variations in Poiqu and its branch, which may be controlled by the discharge and decreases from the Poiqu (11.5 ± 1.2 mm/a) to the tributaries, from 4.8 ± 0.5 mm/a in the Bangcundong gully to 2.4 ± 0.2 mm/a in Zhangmu gully. (3) The fluvial incision rate also shows temporal variations in the Poiqu. There are two periods of low rate and high rate incision processes in the Poiqu, while the section shape transforms from a gentle slope to a cliff. In the low rate period from 24.2 ka BP to 10.0 ka BP in the Poiqu valley, the incision rate was 10.4 ± 1.0 mm/a, while the high fluvial incision rate since 10.0 ka BP was 13.0 ± 1.3 mm/a; (4) The fluvial incision promotes the landscape evolution and triggers the potential landslide in thousands of years. [ABSTRACT FROM AUTHOR]

• The Mijia Shan area is an ideal area to differentiate factors affecting fluvial incision. • River incision in the Mijia Shan is much stronger than that from the Laolongwan Basin, with a difference of 1.21 mm/a. • The Haiyuan fault plays an important role in accelerating the incision rate in the Mijia Shan. In this study, we employed cosmogenic nuclide 10Be analysis to determine the formation ages of the Yellow River terraces in the Mijia Shan and the Laolongwan Basin at the northeastern periphery of the Tibetan Plateau. The aim of this study is to determine local fluvial incision rates and the effect from tectonic activities. The two sets of terraces were surveyed in field and dated by cosmogenic 10Be exposure dating method. The results show that the best-fitting terrace ages in the Mijia Shan are respective 68.0 - 9.4 + 11.2 ka for T11 and 174.7 - 38.4 + 52 ka for T14. In addition, in the Laolongwan basin, sample S3 constrains an age of 123.9 ± 2.7 ka and S2 yields an age of 45.0 ± 1.8 ka. Combining the strath heights of the sampled terraces, the fluvial incision rates were determined. The results showed that the fluvial incision rate of the Yellow River is ∼1.94 mm/a in the Mijia Shan over the last 175 ka, while a much lower incision rate of ∼0.73 mm/a is yielded in the Laolongwan Basin since the last ∼120 ka. The incision rate in the Mijia Shan is almost twice more than that in the Laolongwan Basin. Considering the same climatic condition in both the Mijia Shan and the Laolongwan Basin, the difference between the two incision rates (∼1.21 mm/a) might be due to local tectonic deformation which is derived from the Haiyuan active strike-slip fault. Consequently, our results showed that the Haiyuan fault plays an important role in accelerating the incision rate in the Mijia Shan. Hence, it is suggested that the role of the main geological structures across the main river should also be considered when studying the evolution of terraces of big rivers. [ABSTRACT FROM AUTHOR]

Uranium-series analyses of water-table-type speleothems from Glenwood Cavern and “cavelets” near the town of Glenwood Springs, Colorado, USA, yield incision rates of the Colorado River in Glenwood Canyon for the last ~1.4 My. The incision rates, calculated from dating cave mammillary and cave folia calcite situated 65 and 90 m above the Colorado River, are 174 ± 30 m/My for the last 0.46 My and 144 ± 30 m/My for the last 0.62 My, respectively. These are consistent with incision rates determined from nearby volcanic deposits. In contrast, δ234U model ages (1.39 ± 0.25 My; 1.36 ± 0.25 My; and 1.72 ± 0.25 My) from three different samples of mammillary-like subaqueous crust collected from Glenwood Cavern, 375 m above the Colorado River, yield incision rates of 271 +58/-41 m/My, 277 +61/-42 m/ My, and 218 +36/-27 m/My. These data suggest a relatively fast incision rate between roughly 3 and 1 Ma. The onset of Pleistocene glaciation may have influenced this rate by increasing precipitation on the Colorado Plateau starting at 2.5 Ma. Slowing of incision just before 0.6 Ma could be related to the change in frequency of glacial cycles from 40 to 100 kyr in the middle Pleistocene. This interpretation would suggest that the cutting power of the Colorado River prior to 3 Ma was smaller. An alternative interpretation involving tectonic activity would invoke an episode of fast uplift in the Glenwood Canyon region from 3 to 1 Ma.

Rivers cutting into bedrock to form terrace sequences commonly record a complex history of vertical incision, aggradation of bed cover, and lateral bedrock erosion that can be interpreted as a result of environmental, tectonic, and autogenic changes. The relative magnitudes of changes in vertical and lateral erosion rates has important implications for interpreting the timing and rate of tectonic forcing, as well as the response of rivers to climatic changes [1]. Constraints of detailed vertical and lateral erosion processes and their rates, as well as the potentially complex interactions, are still lacking. Whereas it put forward higher requirements for chronology data. The difficulty in getting well-targeted materials and the uncertainty of dose rates caused by heterogeneous sedimentary environment limit the validity and accuracy of dating. Optical dating of buried rock surface has been applied to dating fluvial terrace cobbles [2], and thus is promising to be employed to reconstruct the vertical and lateral jiggling processes of alluvial rivers. In this study, we exploit fluvial terrace cobble optically stimulated luminescence (OSL) dating, combining with the sandy samples OSL ages with dose rate corrected by inhomogeneous media, to reveal vertical incision, aggradation of bed cover and lateral bedrock erosion of Manas River, and determine their respective rates. Our study deciphered a detailed lateral and vertical jiggling processes of Manas river since the last glacial maximum, and their alternations in response to climatic and tectonic forcing. This study also shed light on understanding the alluvial evolution history for similar geolgocial settings. [ABSTRACT FROM AUTHOR]

The terrace sequence of the Hungarian part of the Danube valley preserves a record of varying tectonic uplift rates along the river course and throughout several climate stages. To establish the chronology of formation of these terraces, two different dating methods were used on alluvial terraces: exposure age dating using in situ produced cosmogenic 10 Be and luminescence dating. Using Monte Carlo approach to model the denudation rate-corrected exposure ages, in situ produced cosmogenic 10 Be samples originated from vertical depth profiles enabled the determination of both the exposure time and the denudation rate. Post-IR IRSL measurements were carried out on K-feldspar samples to obtain the ages of sedimentation. The highest terrace horizon remnants of the study area provided a best estimate erosion-corrected minimum 10 Be exposure age of >700 ka. We propose that the abandonment of the highest terrace of the Hungarian Danube valley was triggered by the combined effect of the beginning tectonic uplift and the onset of major continental glaciations of Quaternary age (around MIS 22). For the lower terraces it was possible to reveal close correlation with MIS stages using IRSL ages. The new chronology enabled the distinction of tIIb (∼90 ka; MIS 5b–c) and tIIIa (∼140 ka; MIS 6) in the study area. Surface denudation rates were well constrained by the cosmogenic 10 Be depth profiles between 5.8 m/Ma and 10.0 m/Ma for all terraces. The calculated maximum incision rates of the Danube relevant for the above determined >700 ka time span were increasing from west (<0.06 mm/a) to east (<0.13 mm/a), toward the more elevated Transdanubian Range. Late Pleistocene incision rates derived from the age of the low terraces (∼0.13–0.15 mm/a) may suggest a slight acceleration of uplift towards present. [ABSTRACT FROM AUTHOR]

ABSTRACT We present new data about the morphological and stratigraphic evolution and the rates of fluvial denudation of the Tavoliere di Puglia plain, a low-relief landscape representing the northernmost sector of the Pliocene-Pleistocene foredeep of the southern Apennines. The study area is located between the easternmost part of the southern Apennine chain and the Gargano promontory and it is characterized by several orders of terraced fluvial deposits, disconformably overlying lower Pleistocene marine clay and organized in a staircase geometry, which recorded the emersion and the long-term incision history of this sector since mid-Pleistocene times. We used the spatial and altimetric distribution of several orders of middle to late Pleistocene fluvial terraces in order to perform paleotopographic reconstruction and GIS-aided eroded volumes estimates. Then, we estimated denudation rates on the basis of the terraces chronostratigraphy, supported by published OSL and AAR dating. Middle to upper Pleistocene denudation rates estimated by means of such an approach are slightly lower than 0.1 mm yr-1, in good agreement with short-term data from direct and indirect evaluation of suspended sediment yield. The analysis of longitudinal river profiles using the stream power erosion model provided additional information on the incision rates of the studied area. Middle to late Quaternary uplift rates (about 0.15 mm yr-1), calculated on the basis of the elevation above sea level of marine deposits outcropping in the easternmost sector of the study area, are quite similar to the erosion rates average value, thus suggesting a steady-state fluvial incision. The approach adopted in this work has demonstrated that erosion rates traditionally obtained by quantitative geomorphic analysis and ksn estimations can be successfully integrated to quantify rates of tectonic or geomorphological processes of a landscape approaching steady-state equilibrium. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Two sulfuric acid speleogenesis (SAS) cave sites in northern Wyoming host speleogenetic byproducts that have been dated using the uranium-series method and thus provide the timing of the SAS events. Gypsum crusts that formed as byproducts of SAS in Lower Kane Cave, exposed by Bighorn River incision into the Little Sheep Mountain anticline, yield uranium-series dates of 20.5 ± 0.2 ka to 16.2 ± 0.2 ka that represent the timing of late stage speleogenesis of that cave. A calcite mammillary engulfed by elemental sulfur that formed during SAS of Shoshone Canyon Conduit Cave, exposed by Shoshone River incision of the homonymous canyon, yielded a uranium-series age of 174 ± 5 ka and represents late stage speleogenesis of that cave, although the process continued after the cave was elevated above the water table until at least 100 ± 5 ka. In addition to the timing of speleogenesis, the U-series results provide incision rates for these two canyons. The rate of canyon incision for the last 200 kyr by the Bighorn River in Little Sheep Mountain Canyon is measured as 190 ± 50 m/Ma, and for the Shoshone River in Shoshone Canyon as 400 ± 40 m/Ma. Using the Bighorn River incision rate, Upper Kane Cave located 33 m above Lower Kane Cave has a projected age of 170 ± 60 ka. We suggest that climatically driven hydrologic mechanisms rather than magmatic ones likely produced the pulses of SAS at these two cave sites. • Uranium-series dating of gypsum and calcite yield sulfuric acid speleogenesis timing. • Sulfuric acid speleogenesis in Lower Kane Cave took place ~20,000 years ago. • Incision rate of Bighorn River is measured using the age of Lower Kane Cave. • Upper Kane Cave age is estimated using the incision rate of the Bighorn River. • Shoshone Canyon Conduit Cave age is used to estimate Shoshone River incision rate. [ABSTRACT FROM AUTHOR]

Abstract: In tectonically active areas, the landscape response to tectonic forcing is described and possibly quantified by regional topographic and hydrographic features as well as by spatial variation in rates of surface processes. We investigated the recent landscape evolution of the Iberian Chain (NE Spain), an intraplate thrust-belt formed in Cenozoic times and characterized by a dome-shaped topography. In its central sector the landscape is dominated by low relief surfaces, Late Neogene (?) in age, presently standing at an average altitude of 1300m. A recent regional uplift controlled the organization of the present fluvial network and dissection of the landscape. In this framework we investigated the geomorphic responses to tectonic forcing by the calculation of morphometric parameters, focusing on topography (map of local relief, swath profiles) and hydrography (basin hypsometric curve and integral, basin asymmetry factor, river longitudinal profiles and relative indices), and using SRTM DEM. The results of morphometric analysis have been coupled with radiometric uranium-series dating of calcareous tufas lying on fluvial strath terraces. The obtained ages allow the estimation of incision rate along the High Tajo and Martín rivers. Our results indicate that uplift and rock-type erodibility are the main factors influencing landscape evolution of the study area. The incision rates are very similar throughout the central sector of the range, indicating that, despite subtle local variation, the rivers are responding to a main tectonic input: the regional uplift. In conclusion, the Iberian Chain landscape is in a transient state in response to a recent dome-like uplift. Indeed, the fluvial processes that weakly incised this landscape at a rate of ~0.6mm/yr are approaching a radial pattern. On the basis of geological and geomorphic constraints, we hypothesize that the uplift started around or after 3Ma. [Copyright &y& Elsevier]

Abstract: During the 1999 Chi-Chi earthquake (Mw =7.6) in Taiwan, the coseismic displacement induced fault scarps and a pop-up structure in the Taan River. The fault scarps across the river experienced maximum vertical slip of 10m, which disturbed the dynamic equilibrium of the fluvial system. As a result, rapid incision in the weak bedrock, with a maximum depth of 20m, was activated within a decade after its armor layer was removed. This case provides an excellent opportunity for closely tracking and recording the progressive evolution of river morphology that is subjected to coseismic uplift. Based on multistaged orthophotographs and digital elevation model (DEM) data, the process of morphology evolution in the uplift reach was divided into four consecutive stages. Plucking is the dominant mechanism of bedrock erosion associated with channel incision and knickpoint migration. The astonishingly high rate of knickpoint retreat (KPR), as rapid as a few hundred meters per year, may be responsible for the rapid incision in the main channel. The reasons for the high rate of KPR are discussed in depth. The total length of the river affected by the coseismic uplift is 5km: 1km in the uplift reach and 4km in the downstream reach. The downstream reach was affected by a reduction in sediment supply and increase in stream power. The KPR cut through the uplift reach within roughly a decade; further significant flooding in the future will mainly cause widening instead of deepening of the channel. [Copyright &y& Elsevier]

Abstract: In this work a series of 5 luminescence and 10Be dated fluvial terraces of the Miño River (NW Iberian Atlantic Margin) is presented. The outcomes allowed answering the longstanding question whether the Miño valley infill has a fluvial or marine origin. The perfect exponential decrease in 10Be concentrations with depth and a progressive increase in age with terrace altitude indicate that the Miño terraces are fluvial terraces rather than terraces incised in older marine basin infill. Accurate dating of the terraces was difficult due to saturation of the luminescence signal and high inheritance of 10Be concentrations. Nevertheless, minimum ages of up to 650ka could be determined and are very likely close to the real ages of the terraces. The age estimations and field evidence suggest that terrace formation and terrace incision occurred during eccentricity-forced cycles of glacio-eustatic sea level changes and tectonic uplift. The occurrence of a steep and narrow continental shelf probably favoured rapid and profound incision by the Miño River during periods of low sea levels. It is furthermore hypothesised that the transition periods between glacials and interglacials were especially important for terrace deposition and incision. Denudation rates of the terraces were calculated from the 10Be data and do not exceed 1.30mMa−1. These extremely low rates are probably the result of a combination of factors that favoured terrace preservation. Large, flat terrace surfaces with high permeability and continuous vegetation cover during the Quaternary stabilised the terrace surfaces. Maximum incision rates, calculated from terrace age and altitude, are 0.07–0.09mka−1. These values can be used as proxies for tectonic uplift rates. They are in agreement with published uplift rates along the northern Spanish coast and the westernmost termination of the Cordillera Cantabrica. This similarity most likely identifies a common tectonic regime leading to similar tectonic uplift rates. The results demonstrate that tectonic uplift occurs in a region that was until very recently considered as tectonically stable. [Copyright &y& Elsevier]

The Osip-cheon River flows along a linear valley that runs approximately parallel to the Osip-cheon Fault. The present study was undertaken to elucidate the tectono-geomorphic evolution of the Osip-cheon Basin during the late Quaternary by employing cosmogenic Be surface exposure dating and optically stimulated luminescence (OSL) dating on a flight of fluvial strath terraces. Several morphometric indices (e.g., stream length-gradient index, asymmetry factor, transverse topographic symmetry factor, stream power incision) for relative tectonic activity are determined with the help of GIS analysis, suggesting minimal tilt of the blocks on either side of the Osip-cheon Fault, with displacement being mainly strike-slip. Thus, it is suggested that the Osipcheon River is a kind of subsequent stream that follows the weakened fault-line in the center of the basin. To determine the fluvial incision rate as an equivalent to the rate of local tectonic uplift, samples for cosmogenic 10Be dating and OSL dating were collected from the surfaces of strath terraces at two different areas along the Osip-cheon River. The terraces can be divided into three groups (T1: oldest to T3: youngest) depending on the height above the present river level. According to our data, the strath terraces formed at ca. 200 ka for T1, ca. 104 ka for T2, and ca. 14 ka for T3. The fluvial incision rate was determined by dividing the height of the terraces above the river by their respective ages. The fluvial incision rate has decreased over the last 200 ka, with a maximum rate of 0.28 mm/yr occurring between T1 and T2 (i.e., ca. 200 ka to 104 ka) followed by a rate of 0.21 mm/yr for the period from T2 to T3 (i.e., ca. 104 ka to ca. 14 ka), and a minimum rate of 0.17 mm/yr since the abandonment of T3 (i.e., over the last 14 ka). Tong-ri Canyon is deeply incised up to the major knickpoint of the Mi-in Falls. Here, the rock-cut strath terraces can be divided into two groups: the farther upstream part of the Tong-ri area (Site-1) was dated to 5.5 ± 0.5 ka, equivalent to the incision rate of 0.26 mm/yr, and the downstream part of the Tong-ri area (Site-5) was dated to 18.5 ± 1.8 ka, equivalent to the incision rate of 0.23 mm/yr. Given the active upstream migration of the knickpoint (Mi-in Falls) found in the upper reach of the river, the incision rate provided by the ages of the strath terraces in the Tong-ri Canyon should be higher than that for any other reach of the river. However, the incision rate of the reach below the mouth of Tong-ri Canyon is similar to the value of the reach above the major knickpoint, suggesting that knickpoint migration in the Tong-ri area was not active during the last 18.5 ka. Rather, it seems to have advanced to a certain level of incision in the past. Along the Osip-cheon River, the values of stream power incision and stream length-gradient show a contrasting distribution. The highest and most anomalous values of these indices are found along the upstream part of the Osip-cheon River. These indices values are likely to be associated with stream piracy. Given the geomorphic features (e.g., elbow of capture, wind gap, waterfall) found in the Tong-ri Canyon area, stream piracy might have been caused by Quaternary reactivation of the Osip-cheon Fault or by the ongoing but slowing, long-term regional tectonic uplift, with an axis along the Taebaek Mountain Range. [ABSTRACT FROM AUTHOR]

Abstract: In Albania, the Osum and Vjoje rivers cross the active graben system and the active frontal thrust system of the Albanides. The effects of climatic and geodynamic forcing on the development of these two rivers were investigated by the means of field mapping, topographic surveying and absolute exposure-age dating. We established the chronology of terraces abandonment from the compilation of new dating (14C and in situ produced 10Be) and previously published data. We identified nine fluvial terraces units developed since Marine Isotope Stage 6 up to historic times. From this reconstituted history, we quantified the vertical uplift on a time scale shorter than the glacial climatic cycle. Regional bulging produces an overall increase of the incision rate from the west to the east that reaches a maximum value of 2.8 m/ka in the hinterland. Local pulses of incision are generated by activation of normal faults. The most active faults have a SW–NE trend and a vertical slip rate ranging from 1.8 to 2.2 m/ka. This study outlines the geodynamic control in the development of rivers flowing through the Albanides on the scale of 103–105ka. [Copyright &y& Elsevier]

Reliable and precise ages of Quaternary pedogenic carbonate can be obtained with 230Th/U dating by thermal ionization mass spectrometry applied to carefully selected milligram-size samples. Datable carbonate can form within a few thousand years of surface stabilization allowing ages of Quaternary deposits and surfaces to be closely estimated. Pedogenic carbonate clast-rinds from gravels of glacio-fluvial terraces in the Wind River Basin have median concentrations of 14 ppm U and 0.07 ppm 232Th, with median (230Th/232Th) = 270, making them well suited for 230Th/U dating. Horizons as thin as 0.5 mm were sampled from polished slabs to reduce averaging of long (≥105 yr), and sometimes visibly discontinuous, depositional histories. Dense, translucent samples with finite 230Th/U ages preserve within-rind stratigraphic order in all cases. Ages for terraces WR4 (167,000 ± 6,400 yr) and WR2 (55,000 ± 8600 yr) indicate a mean incision rate of 0.26 ± 0.05 m per thousand years for the Wind River over the past glacial cycle, slower than inferred from cosmogenic-nuclide dating. Terrace WR3, which formed penecontemporaneously with the final maximum glacial advance of the penultimate Rocky Mountain (Bull Lake) glaciation, has an age of 150,000 ± 8300 yr indicating that it is broadly synchronous with the penultimate global ice volume maximum. [Copyright &y& Elsevier]

The rate of erosion is critical for characterizing landscape evolution and understanding the interactions between tectonic activity, climate, and surface processes in active orogenic belts. This work focuses on the spatial pattern of river incision rate in the northern Tian Shan range, an active orogenic belt in NW China, based on fluvial geomorphic investigations. Both remote and field-based observations have been used to define the terrace sequences of four selected rivers preserved at the mountain front. For each analyzed river, one of the defined terraces (i.e. terrace T 4 of the Kuitun River, terrace T 5 of the Jingou River, terrace T 5 of the Manas River, and terrace T 4 of the Urumqi River) is used as a reference surface from which to reconstruct the paleogeomorphic surface (i.e. the previous riverbed) which was abandoned as a terrace as a result of fluvial incision. By comparing the present-day topography with the reconstructed (pre-incision) landscape, and after a porosity correction, the volume of material eroded by river incision and the depth of incision have been estimated. When combined with the formation age of each reference terrace, the average rates of river incision in the mountain range have been estimated at ~4.1 ± 1.5 mm/yr (Kuitun River), ~3.5 ± 1.4 mm/yr (Jingou River), ~3.1 ± 1.5 mm/yr (Manas River), and ~1.9 ± 1.3 mm/yr (Urumqi River). The above rates display a notable decreasing trend from the Kuitun (west) to the Urumqi (east). Our analyses indicate that lithology and climate might not be the main factors controlling the spatial variation of incision rates in the northern Chinese Tian Shan range. Instead, the observed pattern is in close agreement with changes of slope, relief, and N-S crustal shortening across the range. We thus propose that tectonic activity is the primary factor controlling the erosion and landscape evolution of the northern Tian Shan range, NW China. • The paleogeomorphology in mountain catchments of rivers has been reconstructed using reference terraces. • The volumes eroded by fluvial incision since the formation of the reference terraces have been estimated. • The estimated incision rates display a possible eastward-decreasing trend within the mountain range. • The observed pattern in fluvial incision rates is consistent with the change in N-S crustal shortening across the range. [ABSTRACT FROM AUTHOR]

The Jinsha River has attracted considerable attention for nearly a century due to the morphology of its drainage basin. To explain the evolution of the Jinsha drainage basin, most researchers have considered that the present-day Jinsha (the upper reach of the Yangtze) was once a tributary of a single, southward-flowing river system called the Paleo-Red River, which drained into the South China Sea and was captured by the Upper Yangtze River, after which the flow direction changed to eastwards. The sudden disappearance, at 5.5 Ma, of the Red River submarine fan, which was fed primarily by the Paleo-Red River system, provides an important chronological constraint on the drainage reorganization and the capture event. However, until now, no geomorphic evidence has been presented to support this hypothesized age. Considering this problem, nine well-preserved terraces (T9 to T1) at Jinjiangjie in the Middle Jinsha River were evaluated in this study. To establish the chronological framework of these terraces, a combined dating approach was employed, incorporating electron spin resonance dating, cosmogenic nuclide (26Al/10Be) burial dating, and optically stimulated luminescence dating. We obtained a complete chronological sequence for terraces T9–T1, with ages of approximately 1.07 (T9), 0.70 (T8), 0.65 (T7), 0.51 (T6), 0.47(T5), 0.44(T4), 0.30 (T3), 0.18 (T2), and 0.047 (T1) Ma, respectively. Constrained by this framework, we calculated an average long-term fluvial incision rate of ~147 mm/ka. The reconstruction of the paleo-topography and paleo-drainage, based on digital elevation model data for the re-filling of the deeply incised river valley, indicates that the present drainage pattern in the Middle Jinsha system was established after the disruption of the paleo-landscape surface at an elevation of ~2000 m above sea level. The age of the present-day Middle Jinsha drainage was determined at approximately 5.5 Ma by extrapolating the average valley incision rate, suggesting that the present-day Jinsha was formed at about this time. Our results agree with the previously estimated timing of the disappearance of the Red River submarine fan. • A flight of 9 fluvial terraces dated using ESR, 26Al/10Be and OSL dating in Jinsha River (the upper reach of Yangtze) • About 147 mm/ka of average incision rate in Middle Jinsha River since early Pleistocene • First age of Jinsha River achieving its present-day drainage pattern extrapolated from the average valley incision rate [ABSTRACT FROM AUTHOR]