Geomorphology最新文献

{"title":"The Late Pleistocene - Holocene meandering lower Garonne River, southwest France: Architecture of the valley fill and chronology, comparison with other European rivers","authors":"Pascal Bertran ,&nbsp;Eric Andrieux ,&nbsp;Sophie Leleu ,&nbsp;Zoe Sicard-Delage ,&nbsp;Benjamin Fores ,&nbsp;Rachid Ouchaou ,&nbsp;Pierre Weill ,&nbsp;Jean-Yves Reynaud","doi":"10.1016/j.geomorph.2024.109469","DOIUrl":"10.1016/j.geomorph.2024.109469","url":null,"abstract":"<div><div>The architecture and chronology of Late Pleistocene to Holocene alluvial deposits in the lower Garonne have been studied in details based on data (boreholes, trenches, ground-penetrating radar profiles, numerical dating) collected in quarries and during archaeological surveys. The preserved alluvial bodies, dated between ca. 38 ka and present, show that the river retained a meandering or anabranching pattern throughout this period, associated with the formation of lateral accretion packages and scroll bars in the convexity of meanders. Valley incision in connection to the LGM low sea level reached up to 19 m in the study area, and occurred between ca. 26 and 18 ka. Since ca. 18 ka, the lateral migration of meanders widened the plain without any significant incision of the Oligocene marl bedrock. The Early-Middle Holocene was characterized by the development of highly sinuous meanders, while sinuosity decreased in a late phase including the Little Ice Age. Comparison with other lowland European rivers shows that the persistence of a meandering or anabranching pattern during MIS 2 is not an isolated case. The documented examples are associated with rivers typified by low valley slope, or situated in southern regions unaffected by permafrost and characterized by dense vegetation. The latter conditions would not have led to a drastic change in river discharge and bedload transport during the Last Glacial, as was the case for more northerly rivers where braiding seems to have been common.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"468 ","pages":"Article 109469"},"PeriodicalIF":3.1,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Late pleistocene glacial history of Mount Karadağ, SW Türkiye","authors":"Cihan Bayrakdar ,&nbsp;Zeynel Çılğın ,&nbsp;Faize Sarış ,&nbsp;Serdar Yeşilyurt ,&nbsp;Ferhat Keserci ,&nbsp;Yusuf Büyükdeniz ,&nbsp;Onur Halis ,&nbsp;Christof Vockenhuber ,&nbsp;Susan Ivy-Ochs ,&nbsp;Naki Akçar","doi":"10.1016/j.geomorph.2024.109467","DOIUrl":"10.1016/j.geomorph.2024.109467","url":null,"abstract":"<div><div>Glacial landforms in the southwestern part of the Anatolian Peninsula are found at lower elevations than the rest, suggesting that glaciers were present during the Late Pleistocene. Karadağ, located west of the Western Taurus Mountains, provides evidence of the climatic conditions that facilitated this extensive glaciation. It is characterized by numerous peaks exceeding 2300 m above sea level (asl), with the highest peak reaching 2418 m, making it the region's largest glaciation area. This high mountain mass is composed mainly of limestone and dolomite. This study focuses on the glacial landforms in Karadağ to reconstruct the Late Pleistocene glacial chronology and palaeoclimate of the Western Taurus Mountains. We employed detailed UAV photogrammetry, extensive fieldwork and mapping, surface exposure dating with cosmogenic ³⁶Cl, meteorological measurements, palaeoglacier reconstruction, and palaeo-equilibrium line altitude (pELA) calculations. Karadağ, a topographic barrier to humid air masses from the Mediterranean Sea, ranks as the second wettest area in the Western Taurus Mountains. At a meteorological station we installed in Karadağ, an annual precipitation of 1700 mm or more was recorded, highlighting its significant precipitation. In Karadağ, we have identified two glacial valleys with a maximum length of 4.5 km and six cirques. The glaciers reached their maximum extent around 22.4 ± 2.8 ka during the Last Glacial Maximum (LGM), facilitated by the lowering of the pELA to 2090 m. During the LGM, the glaciers covered an area of approximately 3.5 km² and reached a maximum thickness of about 140 m. Sample TRKR 10 at 2015 m probably belongs to the LGM period. Although a single sample does not conclude definitive conclusions, the presence of the moraine at its highest position indicates the maximum thickness of the glacier. Following the LGM, two more significant glacier advances occurred during the Lateglacial (15.5 ± 2.7 ka) and the Younger Dryas (12.4 ± 1.1 ka). During the late Pleistocene glaciations, and especially during the LGM, Karadağ probably received more precipitation than today, leading to the formation of glaciers at relatively lower elevations than on the Anatolian Peninsula.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"467 ","pages":"Article 109467"},"PeriodicalIF":3.1,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142560772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Annual surface elevation changes of rock glaciers and their geomorphological significance: Examples from the Swiss Alps","authors":"Sebastián Vivero ,&nbsp;Christophe Lambiel","doi":"10.1016/j.geomorph.2024.109487","DOIUrl":"10.1016/j.geomorph.2024.109487","url":null,"abstract":"<div><div>Due to the ongoing degradation of permafrost and the associated impacts on the stability of periglacial mountain slopes, there is a need to improve our understanding of the dynamics of rock glaciers over relatively short timescales. There is also a growing interest in the hydrological role of rock glaciers and other ice-debris landforms, as they can potentially store valuable amounts of ice. Despite the acceleration in rock glacier velocities observed primarily in the European Alps, annual and inter-annual changes in surface elevation and volume have so far escaped detailed quantification in monitoring programs. In this study, annual and biannual uncrewed aerial vehicle (UAV) surveys combined with structure-from-motion (SfM) photogrammetric techniques are used to derive high-resolution surface kinematics, elevation and volume changes of three rock glaciers in the Western Swiss Alps. Between 2016 and 2021, detailed digital elevation model (DEM) differencing revealed a high variability of mean annual elevation changes, reaching up to −0.19 ± 0.02 m/yr (2020−2021) at the Yettes Condjà B rock glacier, while elevation changes at the Les Cliosses rock glacier ranged from −0.05 ± 0.02 m/yr (2016–2017) to +0.014 ± 0.008 m/yr (2021−2021). In addition, the multi-temporal and very high-resolution topographic datasets revealed the presence of distinct rock glacier features, including superimposed lobes, lateral levees and flow divides, that could not be identified previously with traditional in-situ measurements and observations. Our results in terms of elevation and surface velocity changes highlight the importance of detailed and regular high-resolution monitoring for understanding the rapid evolution of active glaciers under the current degradation of mountain permafrost.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"467 ","pages":"Article 109487"},"PeriodicalIF":3.1,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Drainage divide migration between the Yellow and Yangtze Rivers at Eastern Qinling Mountains (central China): Insights from U-Pb ages of detrital rutile","authors":"Yingying Chen ,&nbsp;Yiquan Li ,&nbsp;Xianyan Wang ,&nbsp;Rongqing Zhang ,&nbsp;Wen Lai ,&nbsp;Hanzhi Zhang ,&nbsp;Hengzhi Lyu ,&nbsp;Huayu Lu","doi":"10.1016/j.geomorph.2024.109483","DOIUrl":"10.1016/j.geomorph.2024.109483","url":null,"abstract":"<div><div>Drainage divide migration, influenced by tectonic processes and climate change, significantly shapes geomorphological dynamics and sediment dispersal patterns. However, observing this phenomenon directly is challenging due to its prolonged and dynamic nature. While some researchers have employed simulations to investigate divide migration, these studies often lack the necessary empirical geological validation. The Qinling Mountains in central China, characterized by tectonic uplift and the subsidence of the Weihe Basin, serve as an exceptional natural laboratory for examining the intricate dynamics of the drainage divide between the Yellow and Yangtze Rivers. This study examines the migration history of the Qinling divide since the Cenozoic by analyzing detrital rutile U<img>Pb geochronology from Cenozoic strata within the Weihe Basin. Our results show that rutile U<img>Pb age peaks in the sediments deposited during the Eocene to Early Miocene are principally distributed at 110–300 Ma, 350–680 Ma, 800–840 Ma, and greater than 1000 Ma. From the Late Miocene to the Pliocene, the U<img>Pb age of detrital rutile is mainly distributed at 110–300 Ma and 350–680 Ma. The source signal change revealed by the Weihe Basin deposit sequence in the Late Miocene due to the gradual northward migration of the drainage divide. By examining the chronological evolution of detrital rutile U<img>Pb ages within the basin, we shed light on the trajectory of the Qinling divide's migration, offering new insights into the landscape evolution under the influence of tectonics and climate factors since the Cenozoic.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"467 ","pages":"Article 109483"},"PeriodicalIF":3.1,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Human interventions alter meandering channels evolution: Insights from the inner bank scouring and outer bank deposition in the Jingjiang Reach after the operation of the Three Gorges Dam","authors":"Xin He,&nbsp;Minghui Yu","doi":"10.1016/j.geomorph.2024.109473","DOIUrl":"10.1016/j.geomorph.2024.109473","url":null,"abstract":"<div><div>Geomorphic abnormal responses of consecutive river bends to human activities, such as reservoir constructions and bank protection projects, have not been understood sufficiently. Based on the measured hydrological and topographic data, and remote sensing data, we investigated the morphological adjustments of 17 typical consecutive bends with different curvatures (the ratio of bend width <em>B</em> and bend radius <em>R</em> at the bend apex ranging from 0.22 to 1.96) in the Jingjiang Reach after the Three Gorges Dam (TGD) (2004–2021). The results show that these bends generally experienced inner bank scouring (IBS) and outer bank deposition (OBD). The distance to the dam affects the mechanism of IBS, from being primarily controlled by the water scouring intensity near the dam to the bend curvature and the regime adjustment of the upstream bend. Our results also show that the locations of IBS and OBD in the bends are related to the bend curvature. In sharp bends (<em>B</em>/<em>R</em> &gt; 0.5), IBS occurs in the upper half of the bend, accompanied by OBD near the bend apex. In moderate bends (<em>B</em>/<em>R</em> ≤ 0.5), IBS occurs throughout the whole bend, with OBD near the bend entrance. A higher curvature bend tends to experience greater scouring of the inner bank near the bend apex. Moreover, the effect of upstream bends on downstream bends is revealed. In response to IBS and OBD in the upstream bend, the thalweg at the entrance shifts towards the inner bank, further promoting IBS in the downstream bend. OBD in the downstream bend is intensified by the residual reverse circulation of upstream bend. The results of this study can enhance the understanding of the evolution of meandering rivers in response to human activities, and may serve as a rational reference for managing the meandering rivers downstream of cascade reservoirs.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"467 ","pages":"Article 109473"},"PeriodicalIF":3.1,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thousands of shallow, relict gullies indicate thermo-erosion on the sandy uplands of northern Lower Michigan during the Late Pleistocene","authors":"Christopher J. Baish ,&nbsp;Alanna Post ,&nbsp;Ashton M. Shortridge ,&nbsp;Randall J. Schaetzl ,&nbsp;Parker Hopkins ,&nbsp;Anthony Bowman ,&nbsp;Isabella Rabac ,&nbsp;Bernard Frantz ,&nbsp;Andrew O. Finley","doi":"10.1016/j.geomorph.2024.109482","DOIUrl":"10.1016/j.geomorph.2024.109482","url":null,"abstract":"<div><div>We build on previous work which explained the origin of myriad gullies and incised channels on the dry, sandy uplands of northern Lower Michigan by invoking widespread permafrost. Indicators of permafrost (ice-wedge casts and patterned ground) are known from many sites across the region. Our study area, within an extensive reentrant of the retreating Laurentide Ice Sheet, had been particularly well positioned, geographically, for permafrost. Our goal was to characterize the geomorphic characteristics of the gullies on 72 large ridges, to address the hypothesis that they had formed in association with permafrost. Across the study area, thousands of dry, narrow channels and gullies occur in dense networks, typically with channels aligned directly downslope, in parallel drainage patterns. Most of the gullies exhibit only a minimal amount of incision (ca. 2–3 m), a nearly straight longitudinal profile, and lack a clear depositional fan at their mouth. Even where small fans are present, they are subtle and exhibit little down-fan textural sorting, as would be present in larger, more mature fluvial systems. Gully morphologies did not exhibit strong morphological differences as a function of aspect, as we would have expected for an erosional, periglacial system forming on fairly steep slopes. Nonetheless, in these sandy/gravelly sediments, we could find no other scenario that would have allowed for runoff and gully formation, except ice-rich permafrost that limited infiltration and promoted saturation of the active layer, and eventually, runoff. We conclude that the gullies formed via thermo-erosion into ice-rich permafrost, involving mostly fluvial processes but also some slope failure. Even though thermo-erosion can rapidly form deep gullies, our study area has mainly weak gully forms, perhaps because: (1) permafrost existed here only briefly, (2) the landscape was so cold and the permafrost so ice-rich that runoff was rare, (3) the permafrost on the sandy slopes remained somewhat permeable, limiting runoff, and/or (4) the paleoclimate was so dry that little water was available for sediment transport. We could find no evidence that the gullies developed within preexisting polygonal networks, as is happening today in polar regions under a warming climate. Thus, our study has implications for areas of the Arctic and Antarctic that are, today, experiencing rapid hydrological changes.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"467 ","pages":"Article 109482"},"PeriodicalIF":3.1,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142529707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the effectiveness of “River Morphodynamic Corridors” for flood hazard mapping","authors":"Andrea Brenna,&nbsp;Giacomo Poletto,&nbsp;Nicola Surian","doi":"10.1016/j.geomorph.2024.109460","DOIUrl":"10.1016/j.geomorph.2024.109460","url":null,"abstract":"<div><div>In dynamic rivers the assessment of flood hazard related to geomorphological dynamics assumes crucial importance. Recently, some geomorphological approaches have been developed to assess channel dynamics in response to floods. In this study we explore the River Morphodynamic Corridors which include the current active channel and areas of the alluvial plain that may be (re)activated by channel dynamics during floods. In order to assess the effectiveness of such corridors for mapping flood hazard, we delineated the morphodynamic corridors along a river network of 74 km in the Cordevole River catchment (Italy) and compared the corridors with the channel changes that were triggered by a high-magnitude event (Vaia Storm) that hit the study area in October 2018. We observed that the morphodynamic corridors are capable to define areas where channel dynamics are most likely to occur and have proven satisfactorily effective in predicting channel widenings triggered by a severe flood. The results show that it is crucial to adopt different procedures for corridor delineation based on channel width, i.e., for small streams (width &lt; 30 m) a more precautionary approach should be adopted that considers the entire alluvial plain as an area potentially affected by channel dynamics. The study highlighted an inherent limitation of the approach, since erosion that can affect valley slopes or fluvial terraces (i.e., widening of the alluvial plain) is not taken into account. This application represents the first validation of the River Morphodynamic Corridors approach through comparison with observed flood channel changes. Through this analysis, it can be inferred that, notwithstanding its relatively simple procedure, the approach allows a robust mapping and delineation of flood hazard due to river channel dynamics. The River Morphodynamic Corridors, when applied jointly with hydraulic model for assessing inundation processes, allow an overall assessment of flood hazard, particularly in dynamic river contexts.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"467 ","pages":"Article 109460"},"PeriodicalIF":3.1,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142529711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Glacial cirque identification based on Convolutional Neural Networks","authors":"Dongxue Mao ,&nbsp;Yingkui Li ,&nbsp;Qiang Liu ,&nbsp;Iestyn D. Barr ,&nbsp;Ian S. Evans","doi":"10.1016/j.geomorph.2024.109472","DOIUrl":"10.1016/j.geomorph.2024.109472","url":null,"abstract":"<div><div>Cirques provide important information about the palaeoclimate conditions that produced past glaciers. However, mapping cirques is challenging, time-consuming, and subjective due to their fuzzy boundaries. A recent study tested the potential of using a deep learning algorithm, Convolutional Neural Networks (CNN), to predict boundary boxes containing cirques. Based on a similar CNN method, RetinaNet, we use a dataset of &gt;8000 cirques worldwide and various combinations of digital elevation models and their derivatives to detect these features. We also incorporate the Convolutional Block Attention Module (CBAM) into RetinaNet for training and prediction. The precision of cirque detection with or without the addition of the CBAM is evaluated for various input data combinations, and training sample sizes, based on comparison with mapped cirques in two test areas on the Kamchatka Peninsula and the Gangdise Mountains. The results show that the addition of CBAM increases the average precision by 4–5 % (<em>p</em> &lt; 0.01), and the trained model can detect the cirque boundary boxes with high precision (84.7 % and 87.0 %), recall (94.7 % and 86.6 %), and <em>F</em>_<em>1</em> score (0.89 and 0.87), for the two test areas, respectively. The inclusion of CBAM also significantly reduces the number of undetected cirques. The model performance is affected by the quantity and quality of the training samples: the performance generally increases with increasing training samples and a training dataset of 6000 cirques produces the best results. This trained model can effectively detect boundary boxes that contain cirques to help facilitate subsequent cirque outline extraction and morphological analysis.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"467 ","pages":"Article 109472"},"PeriodicalIF":3.1,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142537224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Understanding sediment and carbon accumulation in macrotidal minerogenic saltmarshes for climate resilience","authors":"Amann Benjamin ,&nbsp;Chaumillon Eric ,&nbsp;Bertin Xavier ,&nbsp;Pignon-Mussaud Cécilia ,&nbsp;Marie-Claire Perello ,&nbsp;Christine Dupuy ,&nbsp;Long Nathalie ,&nbsp;Schmidt Sabine","doi":"10.1016/j.geomorph.2024.109465","DOIUrl":"10.1016/j.geomorph.2024.109465","url":null,"abstract":"<div><div>Coastal saltmarshes play an essential role in providing services such as sediment and carbon storage, coastal protection and support for biodiversity. Despite their importance, understanding the factors controlling sediment and carbon accumulation in these minerogenic saltmarshes remains challenging due to their diversity and site-specific characteristics. Understanding the respective role of these drivers is essential for effective coastal management, particularly for mitigating the impacts of climate change. This study evaluates the control of forcing factors on the lateral and vertical morphological evolution and carbon burial rates of three minerogenic saltmarshes located on the French Atlantic coast (Pertuis Charentais region). By focusing on these sites, the study isolates specific factors such as wind and wave exposure, inundation frequency, and sediment availability, while minimizing confounding influences like climate and tidal range. Results reveal significant lateral expansion of saltmarsh boundaries towards the sea across all sites, with the highest rates of progradation observed in the protected areas influenced by geomorphological features such as sand spits and sheltered bay heads. Sediment and mass accumulation rates (SAR; MAR), derived from ²¹⁰Pb and ¹³⁷Cs profiles of sediment cores (<em>n</em> = 14), range from 0.48 to 2.22 cm yr⁻¹, among the highest reported globally, with notable variability within and between sites. Inundation frequency and accommodation space explain SAR variability within sites, while sediment availability predominantly determines spatial differences in vertical accumulation rates between sites. Organic carbon burial rates range from 75 to 345 gC m⁻² yr⁻¹, and show a strong correlation with SAR (<em>r</em> = 0.9, <em>p</em> <em>&lt;</em> 0.001, <em>n</em> = 13) but no dependence on carbon content or density (<em>r</em> = 0.2, <em>p</em> <em>&gt;</em> 0.05, n = 13). This highlights the role of sediment input in the accumulation and sequestration of carbon by minerogenic saltmarshes. Furthermore, isotopic analysis indicates a marine source dominance in organic carbon sediment. This research provides insights into how different environmental conditions affect saltmarsh morphological evolution and carbon sequestration rates, informing targeted coastal management strategies focused on enhancing ecosystem resilience and climate resilience.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"467 ","pages":"Article 109465"},"PeriodicalIF":3.1,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Constraining the origin of the Norwegian strandflat – The influence of isostatic and dynamic surface changes","authors":"Cecilia E. Nielsen ,&nbsp;Jane L. Andersen ,&nbsp;Annina Margreth ,&nbsp;Ola Fredin ,&nbsp;Vivi K. Pedersen","doi":"10.1016/j.geomorph.2024.109484","DOIUrl":"10.1016/j.geomorph.2024.109484","url":null,"abstract":"<div><div>The Norwegian strandflat is a prominent low-relief bedrock surface found near sea level along most of the west coast of Norway. Its origin has been discussed throughout the last 130 years but is yet to be resolved. Some studies suggest that the strandflat represent a tropical weathering front of Mesozoic age that has since been buried and re-exhumed, while others relate its origin to Pleistocene periglacial and glacial processes and/or wave-induced weathering and erosion. Previous interpretations of the strandflat have considered postglacial isostatic uplift, but the impacts of isostatic changes due to glacial erosion and deposition, as well as dynamic surface changes driven by mantle convection, have been largely overlooked. Here we examine how geomorphological-driven isostatic changes and dynamic surface changes have influenced the land-surface elevation along the Norwegian coast during late Pliocene-Quaternary (the last ca. 3 million years). We employ quantitative estimates of glacial erosion and deposition to assess the flexural isostatic response from the resulting load changes. Our analyses show that patterns of geomorphic isostatic adjustments and dynamic surface changes are generally not reflected in the present elevation of the strandflat. Only the loading effect from the deposition of the North Sea Fan can clearly be correlated with the submerged strandflat found near Stad (∼62 °N). Our results imply that if the strandflat formed synchronously along the Norwegian coast as a flat surface at sea level, the strandflat we observe today must have developed after the majority of late Pliocene-Quaternary glacial erosion took place, but prior to the main deposition of the North Sea Fan. This would place strandflat formation within the last few glacial cycles, but before the Last Glacial Maximum (LGM). This inferred pre-LGM age of the strandflat is generally consistent with cosmogenic nuclide exposure ages and observed striations on the strandflat. Finally, we examine ice cover and land-surface changes relative to sea level during the last 80,000 years and find no extended periods favorable for synchronous strandflat formation across all regions along the Norwegian coast. This implies that either the strandflat is diachronous, or that the processes of formation have either been extremely fast under certain conditions or are independent of sea level, for instance related to glacial erosion.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"467 ","pages":"Article 109484"},"PeriodicalIF":3.1,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}