Geomorphology最新文献

{"title":"Imprint of a dead-ice environment on lidar imagery—Spatial patterns at the last Scandinavian Ice Sheet margin (N Poland)","authors":"Barbara Woronko ,&nbsp;Weronika Danel ,&nbsp;Mirosław Błaszkiewicz ,&nbsp;Piotr Hermanowski ,&nbsp;Olaf Juschus ,&nbsp;Mateusz Kramkowski ,&nbsp;Bruno Garrett ,&nbsp;Achim Brauer","doi":"10.1016/j.geomorph.2024.109434","DOIUrl":"10.1016/j.geomorph.2024.109434","url":null,"abstract":"<div><div>There is a unique glacial landscape system in the southern Żarnowiec Moraine Plateau of northern Poland. Here the terrain is characterized by a very high concentration of ridges that are often adjacent to pits, which together constitutes a special type of hummocky topography. The morphological diversity of the study-area ridges and pits was determined from high-resolution lidar imagery that was qualitatively and quantitatively processed, then analysed. Fourteen test fields of spatial dimensions 0.5 km × 0.5 km were selected within the moraine plateau for detailed studies. The results show that the ridges and pits constitute a very dense network of approximately circular, diverse-oriented forms of various sizes, most of which are linked to each other in a step-wise fashion. The pits are surrounded by ridges of various heights and widths that separate one pit from another. A characteristic feature of the studied pits is the orientation of their long axis. Form-based morphological analysis revealed that their genesis was associated with a glacial rather than a periglacial environment. It is believed that ridge orientation reflects a spatial pattern related to ice crevasses. A moraine plateau constituted a terrain obstacle that acted as a counterslope to the advancing ice sheet. The studied landforms and landscape resulted from the ice sheet's breaking up into dead-ice blocks of various sizes. The very dense system of perpendicular, parallel, and diagonal crevasses was related to ice sheet advance from a northerly direction, resulting in a flow around the obstacle and differences in ice-mass speed.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"466 ","pages":"Article 109434"},"PeriodicalIF":3.1,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142358200","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":"Strandline records of high frequency, low magnitude drops in water level, glacial Lake Agassiz basin, Central Polk County, MN, USA","authors":"Maureen P.R. Casaus ,&nbsp;Timothy G. Fisher ,&nbsp;Harry M. Jol ,&nbsp;Kenneth Lepper","doi":"10.1016/j.geomorph.2024.109433","DOIUrl":"10.1016/j.geomorph.2024.109433","url":null,"abstract":"<div><div>Glacial Lake Agassiz strandlines expressed in LiDAR-based digital elevation models are detailed records of past water level change that reflect outlet incision and switching. Detailed 1:24,000 scale surficial geology mapping of a small section of coastline east of Crookston, MN, reveals strandlines of the Lockhart, Emerson, and Nipigon phases. Other than the Campbell and youngest Tintah Beach, the strandlines are not identified using the naming convention established near the southern outlet (Herman, Norcross, Upham, Tintah) because of the increasing number of strandlines northwards. The strandlines, for the most part, naturally exist in elevation clusters, and are assigned to 11 strandline groups (SG). SGs 1–9 are of Lockhart age at elevations higher than the Tintah Campbell Gap (TCGap). Elevation gaps between SGs are ~1–3 m, greater than the 0.5–2 m gap between successive strandlines within a SG. The many (<em>n</em> = 70) small, low-relief strandlines are interpreted to record nearly continuous incision of the southern outlet sill during Lockhart Phase. Beach ridges are estimated to have formed every ~20 years. The TCGap is ~4 km wide in the study area. The Campbell Beach of Emerson Phase age consists of several embayments, beach ridges and the large Melvin Spit. Based on morphological comparison with the modern Gull Point Spit in the Lake Erie basin, the Melvin Spit took ~500 years to form, during which water level dropped 8 m. The Nipigon Phase strandlines are small discontinuous beach ridges. North-south elevation plots of the most continuous strandline in each SG records southward slopes of 1.1 to 0.19 m/km explained by differential glacioisostatic adjustment active during strandline development that decreases through time at lower elevations. The three highest elevation OSL dates agree with published ages for the older strandlines (~14.4 ± 1.5 ka), but younger dated Tintah, Campbell, and sub-Campbell beaches are 2–5 ka older than published ages. Ground penetrating radar (GPR) datasets acquired at 11 sites at frequencies between 100 and 500 MHz, representing a cumulative distance of 11 km, form the basis for a simple beach ridge formation model augmented with hand auger holes and shallow hand-dug pits. Six radar facies (RF) were identified, dominated by RF2 which consists of lakeward-dipping reflections with a downlapping lower boundary recording a depositional regressive system, and RF4 which consists of landward-dipping reflections with a downlapping lower boundary recording overwash deposits from proposed storm events. Spit orientations and GPR data indicate littoral drift was southwards with offshore bars possibly nucleating successive beach ridges upon ~1-m drops in water level. Detailed analysis of strandlines from paleo lakes offer promise for high resolution reconstructions of past water level history.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"466 ","pages":"Article 109433"},"PeriodicalIF":3.1,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142318926","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":"Monsoon control on evolution of the western Indian aeolian landscape: Insights from U-Pb detrital zircon geochronology and Sr-Nd-Hf isotope studies of the Thar Desert sand dunes","authors":"B.G. George ,&nbsp;A. Maitra ,&nbsp;R. Anczkiewicz","doi":"10.1016/j.geomorph.2024.109429","DOIUrl":"10.1016/j.geomorph.2024.109429","url":null,"abstract":"<div><p>Evolution of landscape is linked to the interplay of tectonics, lithology, and climate. To better understand the evolution of aeolian landscape of the western Indian subcontinent and its major driver/s, we carried out a quantitative provenance analysis of the sand dunes of Thar Desert and desert river Luni using whole rock Sr-Nd-Hf isotopes and detrital zircon U-Pb geochronology. Our findings show Himalayan origin for the Thar sands. River Indus consistently contributed about 30–40 % of the total dune sand across the desert. The sand dunes in the north and the west of the desert are dominated by sediments derived from the source rocks drained by Sutlej river and its tributary Beas river whereas the dunes of central Thar are dominated by sediments supplied by rocks drained by Jhelum, Ravi and Chenab rivers. Analysis of detrital zircon U-Pb age spectra of sediments from desert river Luni reveal that dune sand of southern Thar Desert forms nearly 80 % of its present-day sediment load. Notably, the Thar dune sands show remarkable compositional similarity to the early to middle Holocene Indus delta sediments suggesting shared source/s. Existing paleolimnological and climatic records suggest a wetter environment in the Thar during early to middle Holocene. This evidence coupled with compositional similarities between the Thar dunes and the Indus delta sediments from the same period, indicate a probable extension of the Indus-Sutlej floodplain into southeast Thar during that time. Subsequent aridification of the region in the late Holocene likely led to seasonal winds recycling this fluvial sand to form the present-day Thar dunes, and shaping the current aeolian landscape in western India.</p></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"466 ","pages":"Article 109429"},"PeriodicalIF":3.1,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142243724","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":"Alluvial floodplain gully erosion in dryland rivers – An overlooked source of sediment with implications for river condition and management","authors":"Marita R. Pearson ,&nbsp;Michael A. Reid ,&nbsp;Timothy J. Ralph ,&nbsp;Cara Masere","doi":"10.1016/j.geomorph.2024.109430","DOIUrl":"10.1016/j.geomorph.2024.109430","url":null,"abstract":"<div><p>Dryland alluvial rivers are naturally complex systems with a range of in-stream and floodplain geomorphic units that provide habitat for aquatic and terrestrial biota. These systems are increasingly threatened by accelerated rates of sedimentation leading to declines in geomorphic complexity, habitat quality, and ponding depth. The implications of sedimentation on waterholes, or deep pools, is of particular concern, as they provide critical refugia in arid environments. However, sources of sediment entering and infilling waterholes, and the flow-on effects for habitat and water quality, are not well understood. This study addresses the potential for sediment derived from alluvial floodplain gullies to influence geomorphic change in dryland rivers. Alluvial floodplain gullies are often overlooked in comparison to more widely documented hillslope, or colluvial, gullies. Alluvial gullying is a prevalent feature of the Barwon-Darling River, one of Australia's longest and most important waterways in the northern Murray-Darling Basin (MDB). The estimated volume of sediment derived from floodplain gullies is 168 million m³, which far exceeds estimates used in past sediment budgets. Gully size and complexity varied from small, linear features to large, complex, branching gullies and the total number of gullies increased by ~40 % from the 1960s to 2000s. However, the more recent episodes of gullying (i.e., post 1960s) are limited to smaller gullies, which are likely to yield less sediment than the side walls of the older, larger, more complex gullies. Based on the average decline in maximum waterhole depth, ~19 million m³ of sediment has accumulated in Barwon-Darling waterholes over the past 120 years (equivalent to ~158,000 m³ a⁻¹). A predictive relationship between gully volume and change in waterhole depth was expected, but not observed. Nevertheless, the role of alluvial floodplain gullies as a significant source of sediment should not be overlooked when assessing dryland river forms and processes. River management should consider the implications of changing sediment sources and in-stream loads, with associated changes in water quality and aquatic habitats, which influence river condition.</p></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"466 ","pages":"Article 109430"},"PeriodicalIF":3.1,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272444","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":"Global survey of paleo-bedforms on Mars","authors":"Matthew Chojnacki ,&nbsp;Lori K. Fenton ,&nbsp;Lauren A. Edgar ,&nbsp;Mackenzie Day ,&nbsp;Christopher S. Edwards ,&nbsp;Aaron R. Weintraub ,&nbsp;Amber L. Gullikson ,&nbsp;Matt W. Telfer","doi":"10.1016/j.geomorph.2024.109428","DOIUrl":"10.1016/j.geomorph.2024.109428","url":null,"abstract":"<div><div>Sedimentary processes on Mars have contributed to a plethora of landforms, both ancient and modern. Many of these are aeolian- or fluvial-formed constructs that meet the morphologic criteria for dunes and ripples but are clearly lithified and part of the rock record. This study conducted a survey of Mars using data returned from the High Resolution Imaging Science Experiment (HiRISE) to characterize the spatial distribution, origin, and geologic context of these preserved ancient bedforms, termed here as paleo-bedforms. The most compelling class include organized groups of 2–80-m-tall, crescentic to transverse features spaced at 100–1000 m wavelengths at Apollinaris Sulci, Valles Marineris, and other low-latitude sites. These morphologies along with superposed craters, boulders, and fractures led to the interpretation that these are highly lithified, friable, and partially eroded ancient aeolian dunes. In addition to lithified dunes, other remnants of ancient bedforms include examples in which the dune was completely removed, leaving a shallow depression in a crescentic outline as dune cast pits. The most widespread occurrences of paleo-bedforms show crest-to-crest wavelengths (10–80 m), heights (∼1–4 m), and morphologies consistent with lower-order bedforms of megaripples or transverse aeolian ridges. Paleo-megaripple fields in Arcadia Planitia, Hellas Planitia, Terra Sirenum, and other locations exhibit a progression of degraded morphologies, with crests showing signs of rounding, pitting, or fracturing, while heights and slopes are diminished due to erosion. Most rare are the paleo-bedforms in the fluvial bedform class at Lethe Vallis and Holden crater, as they occur along the path of proposed ancient flooding events. More enigmatic paleo-bedform candidates occur concentrated along the steep Valles Marineris and Noctis Labyrinthus wall slopes. These intermediate-sized, arcuate landforms that resemble transverse climbing dunes are heavily cratered, but they may align perpendicular or oblique to the local gradient, perhaps formed by wall slope winds and slope creep.</div><div>The bedforms are unlike most ancient terrestrial aeolian or fluvial bedform systems, which are typically preserved only as truncated members of stratigraphic sections. Episodes of burial and exhumation by various geologic units (e.g., the Medusae Fossae Formation, pyroclastic units, lava flows, dust) are notable, whereas other bedforms appear to have been stabilized and partially lithified in place without burial. Ongoing agents of mass wasting, aeolian abrasion, and cryo-driven processes have contributed to the exhumation, erosion, and weathered appearance of paleo-bedforms, and a spectrum of degradation states was observed. Collectively, we report a diverse variety of ancient sedimentary bedforms preserved across Mars, with implications about paleoclimates and landscape evolution on Mars.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"466 ","pages":"Article 109428"},"PeriodicalIF":3.1,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142322519","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":"Mid-Miocene (17–11 Ma) fast exhumation in the upper Jinsha River and its implication for regional faulting in Southeast Tibet","authors":"Xuwen Shen ,&nbsp;Jing Liu-Zeng ,&nbsp;Xiaoming Shen ,&nbsp;Xianyang Zeng ,&nbsp;Zijun Wang ,&nbsp;Yukun Xing ,&nbsp;Heng Wang ,&nbsp;Mohan Li","doi":"10.1016/j.geomorph.2024.109431","DOIUrl":"10.1016/j.geomorph.2024.109431","url":null,"abstract":"<div><p>The rugged southeast (SE) Tibet hosts a network of evolving faults, many of which are poorly understood due to a lack of sedimentary records and poor accessibility. The Jinsha River fault zone (JRFZ) is vaguely considered as a major fault bounding the Chuan-Dian Block in the northwest, yet little is known about its tectonic evolution history, which hinders our clear understanding of the tectonic deformation pattern, process and geomorphic response of SE Tibet. Here, we collected 10 samples from the hanging wall of the Xiongsong reverse fault, one strand of the JRFZ, near Markam area and on the trunk of the upper Jinsha River, to reveal its exhumation and kinematic history through low-temperature thermochronology. The ZHe ages (~17–13 Ma) of the samples from the hanging wall are much younger than the published ones in the footwall, but the AFT (~11–9 Ma) and AHe ages (~14–6 Ma) are only slightly younger than those in the footwall. The QTQt and 3-D thermo-kinematic Pecube modeling suggest consistently that the Xiongsong fault experienced strong activity during the mid-Miocene (~17–11 Ma) and then weakened. Post-11 Ma decreases in exhumation here on the trunk of the Jinsha river, if interpreted as river incision, is opposite to previously inferred river response to late Miocene surface uplift driven by the lower crust flow. Significant differences in thermochronological data and modeling results on both sides of the Jinsha River indicate the importance of local faulting in the development of large rivers. In addition, late Miocene fault activity shifts have also been observed on other major structures in SE Tibet, such as the left-lateral faulting of the Xianshuihe-Xiaojiang fault, the enhanced thrusting of the Longmen Shan-Yalong thrust belt and the kinematic reversal of the Ailao Shan-Red River shear zone. We infer that the near synchronized change in regional fault activity may be caused by the clockwise rotation of SE Tibet, while its being extruded southeastward from the pushing front of the Indian collision.</p></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"466 ","pages":"Article 109431"},"PeriodicalIF":3.1,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142261986","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":"A model-based characterization of confined meandering rivers","authors":"Hossein Amini ,&nbsp;Stefano Lanzoni ,&nbsp;Federico Monegaglia ,&nbsp;Marco Tubino ,&nbsp;Guido Zolezzi","doi":"10.1016/j.geomorph.2024.109427","DOIUrl":"10.1016/j.geomorph.2024.109427","url":null,"abstract":"<div><p>In this paper we analyze the dynamics of meandering rivers that flow in geologically confined floodplains. We use a state of art meander morphodynamic model in which the floodplain erodibility can be spatially variable, and can thus be highly reduced where nearly unerodible lateral walls are simulated. We propose a hybrid empirical and model-based indicator to estimate the degree of confinement relative to the potential, unconfined meander belt. Together with commonly used meander morphometric indicators, we propose two novel planform metrics to represent the observed tendency of confined meanders (i) to develop long reaches attached to the geological boundaries, and (ii) to develop more frequent crossing of the floodplain central axis. Results reproduce realistic planforms of confined meanders, quantitatively support previously suggested qualitative classifications of confined meandering rivers, and provide a rational framework to compare meandering rivers having different degree of confinement (strong, moderate, unconfined), as well as different hydro-morphological conditions. Good agreement between model predictions and the few existing field observations support the proposed approach.</p></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"466 ","pages":"Article 109427"},"PeriodicalIF":3.1,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142243723","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":"Shore ice control on coastal geomorphic evolution in cold regions","authors":"E.J. Theuerkauf ,&nbsp;L.K. Zoet ,&nbsp;C.A. Volpano ,&nbsp;S.E. Dodge ,&nbsp;B.M. Hartley ,&nbsp;J. Elmo Rawling III","doi":"10.1016/j.geomorph.2024.109409","DOIUrl":"10.1016/j.geomorph.2024.109409","url":null,"abstract":"<div><p>Shore ice is a common feature on cold climate coasts, which are abundant in mid- and high-latitude regions, however it is understudied. Previous research has reported both beach protection and erosion as potential impacts from shore ice presence. Altered ice dynamics resulting from a changing climate are likely to intensify these impacts. To address this discrepancy and improve future coastal change predictions we conducted the first combined field, laboratory and modeling study of shore-ice processes and impacts. Beach and nearshore morphology mapping, experiments with a novel cryogenic wave tank, and 3D coastal evolution modeling revealed that shore ice protected the beach from storms, but scoured the nearshore at the ice edge and transported sediment offshore, likely past the depth of closure. This resulted in enhanced beach erosion during the ice-free and non-storm season, countering the protective benefit from the ice. This study indicates that shore ice plays an important and likely evolving role in geomorphic evolution along cold climate coasts.</p></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"466 ","pages":"Article 109409"},"PeriodicalIF":3.1,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142172749","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":"Geomorphological and sedimentary traces of historical and modern exceptional flooding events in a dry valley of the Andean Precordillera (Tarapacá Region, N Chile)","authors":"Katharina Seeger ,&nbsp;Simon Matthias May ,&nbsp;Dominik Brill ,&nbsp;Marina Herbrecht ,&nbsp;Dirk Hoffmeister ,&nbsp;Dietmar Quandt ,&nbsp;Alexandra Stoll ,&nbsp;Alexander Rhein ,&nbsp;Maximilian Keiser ,&nbsp;Dennis Wolf ,&nbsp;Olaf Bubenzer","doi":"10.1016/j.geomorph.2024.109417","DOIUrl":"10.1016/j.geomorph.2024.109417","url":null,"abstract":"<div><div>While palaeoenvironmental records of the Atacama Desert and Andean Altiplano region document wet conditions related to the Central Andean Pluvial Events in the late Pleistocene/early Holocene, the spatio-temporal pattern of mid- to late Holocene or even historical climatic fluctuations so far remains ambiguous with only few records documenting the climatic conditions over the last centuries. Uncertainties remain particularly for latitudes around 20°S and for the Andean Precordillera in general. These need to be addressed in order to decipher the spatial extent and potential linkage of hydroclimatic changes observed in palaeoenvironmental records from the Andes and the Pampa del Tamarugal basin from ∼18 to ∼25°S. This study aims to shed light on historical flooding activity in a dry (ephemeral) valley east of Pica town in the lower Andean Precordillera (Tarapacá Region, N Chile), which is characterised by steep, slump-dominated slopes with aeolian sediments and generally short sediment transport distances. Combined remote sensing, sedimentological and chronostratigraphical investigations were applied to study the geomorphological and sedimentary impact of flood-related morphodynamics on the valley and the sedimentary record, using the recent February 2019 flooding event as a reference. Our methodological approach allowed for the differentiation of flood-related from aeolian deposits. Three facies of flood-type deposits were identified, namely slackwater, channel-type and levee-type deposits. While the February 2019 flooding constitutes an unprecedented event for the era of satellite imagery since 1966, past flooding activity in the valley, comparable to the 2019 event, was reconstructed to have occurred at ∼300 years ago and during the late 19th to early 20th century. The spatio-temporal pattern of flooding activity with a multi-decadal to centennial cyclicity derived from this study seems to be synchronous to hydroclimatic fluctuations reconstructed from other palaeo-records in the Altiplano and proves the sensitivity of the Precordilleran valleys to palaeoenvironmental and palaeoclimatic fluctuations in the broader area.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"466 ","pages":"Article 109417"},"PeriodicalIF":3.1,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310795","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":"Multi-millennia surface dynamics: Novel investigation approach unveils climate relation to mountain erosion (Serra da Estrela, Portugal)","authors":"Gerald Raab ,&nbsp;Gonçalo Vieira ,&nbsp;Piotr Migoń ,&nbsp;Dmitry Tikhomirov ,&nbsp;Marcus Christl ,&nbsp;Markus Egli ,&nbsp;Fabio Scarciglia","doi":"10.1016/j.geomorph.2024.109416","DOIUrl":"10.1016/j.geomorph.2024.109416","url":null,"abstract":"<div><p>Multi-millennia data logs on surface denudation variation in alpine landscapes are scarce, yet they are needed to understand the impacts of environmental changes on denudation. On the example of the Serra da Estrela plateau in Portugal, we explored a new archive, vertical bedrock outcrops (tors), and the capability of the Tor Exhumation/Exposure Approach (TEA) to capture surface denudation variations even in formerly glaciated landscapes. Therefore, we used vertical in-situ ¹⁰Be to date surface exposure of tor slopes in formerly glaciated and non-glaciated parts of the plateau during the last glacial period.</p><p>Based on the surface exposure ages, surface denudation variations covering the last ∼200 ka could be derived that revealed glacial retreat dynamics in greater detail. Higher isotope contents and, thus, surface exposure ages were found in the non-glaciated area. At the formerly glaciated sites, the ice margin retreat is reflected in the isotope signature of the tors. The younger rock surfaces had a higher chemical weathering degree than older surfaces at the non-glaciated site as a result of a higher water availability. Highest-elevation tors have experienced (subglacial/hydrothermal) chemical weathering, mass wasting and stripping (∼6 ± 0.5 ka) during the transition from a cool moist, to an oceanic-Mediterranean climate.</p><p>Yet, tors in the non-glaciated area yielded lower surface denudation rates with a maximum of 0.53 [mm yr⁻¹] compared to the glaciated area (reaching values of up to 18.29 [mm yr⁻¹]). Since the LGM and the concomitant increase in air temperature, surface denudation also distinctly changed. Temperature trends and surface denudation developed analogously for the last ∼150 ka. Vegetation change or human activity's impact on surface denudation cannot be discerned due to the too low chronological resolution. Overall, we demonstrated that multi-millennia tor records of variation in surface denudation can be obtained using the TEA, even in formerly glaciated areas. Thus, this study contributes to revealing the sensitivity of mountain erosion rates to past environmental changes.</p></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"466 ","pages":"Article 109416"},"PeriodicalIF":3.1,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142172748","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}