Journal of Quaternary Science最新文献

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Behavioural tendencies of the last British–Irish Ice Sheet revealed by data–model comparison 通过数据与模型对比揭示最后一块英爱冰原的行为趋势
IF 1.9 3区 地球科学
Journal of Quaternary Science Pub Date : 2024-06-14 DOI: 10.1002/jqs.3628
Jeremy C. Ely, Chris D. Clark, Sarah L. Bradley, Lauren Gregoire, Niall Gandy, Ed Gasson, Remy L.J. Veness, Rosie Archer
{"title":"Behavioural tendencies of the last British–Irish Ice Sheet revealed by data–model comparison","authors":"Jeremy C. Ely,&nbsp;Chris D. Clark,&nbsp;Sarah L. Bradley,&nbsp;Lauren Gregoire,&nbsp;Niall Gandy,&nbsp;Ed Gasson,&nbsp;Remy L.J. Veness,&nbsp;Rosie Archer","doi":"10.1002/jqs.3628","DOIUrl":"10.1002/jqs.3628","url":null,"abstract":"<p>Integrating ice-sheet models with empirical data pertaining to palaeo-ice sheets promotes advances in the models used in sea-level predictions and can improve our understanding of past ice-sheet behaviour. The large number of empirical constraints on the last British–Irish Ice Sheet make it ideal for model–data comparison experiments. Here, we present an ensemble of 600 model simulations, which are compared with data on former ice-flow extent, flow geometry and deglaciation timing. Simulations which poorly recreate data were ruled out, allowing us to examine the remaining physically realistic simulations which capture the ice sheets' behavioural tendencies. Our results led to a novel reconstruction of behaviour in the data-poor region of the North Sea, insights into the ice stream, potential ice-shelf and readvance dynamics, and the potential locations of peripheral ice caps. We also propose that the asynchronous behaviour of the British–Irish Ice Sheet is a consequence of the geography of the British Isles and the merging and splitting of different bodies of ice through saddle merger and collapse. Furthermore, persistent model–data mismatches highlight the need for model development, especially regarding the physics of ice–ocean interactions. Thus, this work highlights the power of integrating models and data, a long-held aim of palaeoglaciology.</p>","PeriodicalId":16929,"journal":{"name":"Journal of Quaternary Science","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jqs.3628","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141341641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Submerged imprint of glacier dynamics in the NW sector of Lago Viedma (southern Patagonia, Argentina) 维德玛湖(阿根廷巴塔哥尼亚南部)西北部冰川动力学的沉没印记
IF 1.9 3区 地球科学
Journal of Quaternary Science Pub Date : 2024-06-12 DOI: 10.1002/jqs.3625
F. B. Restelli, J. G. Lozano, D. M. Bran, S. Bunicontro, E. Lodolo, A. A. Tassone, J. F. Vilas
{"title":"Submerged imprint of glacier dynamics in the NW sector of Lago Viedma (southern Patagonia, Argentina)","authors":"F. B. Restelli,&nbsp;J. G. Lozano,&nbsp;D. M. Bran,&nbsp;S. Bunicontro,&nbsp;E. Lodolo,&nbsp;A. A. Tassone,&nbsp;J. F. Vilas","doi":"10.1002/jqs.3625","DOIUrl":"10.1002/jqs.3625","url":null,"abstract":"<div>\u0000 \u0000 <p>Lago Viedma is a proglacial lake into which the Viedma Glacier flows from the Southern Patagonian Ice Field. This glacier has rapidly lost mass in recent times, and its deglacial history is reflected in the lake's subsurface. New high-resolution multi-channel seismic profiles acquired in the northwestern sector of the lake have allowed us to reconstruct the bathymetry of the area and identify several small sub-basins, which have a maximum depth of 240 m in this sector. Four seismic facies have been recognized, separated by erosional unconformities, reflecting the depositional conditions in this sector of the basin during different Quaternary sedimentation phases. There is a transitional phase from ice-contacted deposits to subglacial deposits, probably associated with a subglacial fan, and finally a phase of lacustrine sedimentation. In addition, three depositional stages were identified within the lacustrine deposits, indicating a different sedimentary input, and the morphologies observed at the lake bottom suggest the existence of at least ten stagnations of the glacial margin. This study helps to improve the history of the retreat of the Viedma Glacier in this area during the Pleistocene/Holocene and provides a basis for further geophysical measurements aimed at mapping this remote lacustrine environment.</p>\u0000 </div>","PeriodicalId":16929,"journal":{"name":"Journal of Quaternary Science","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141353277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Defining the Sheldon Creek Formation, a Middle Wisconsinan (MIS 3) till in Iowa, USA 确定美国爱荷华州谢尔顿溪地层--威斯康星中统(MIS 3)沉积层
IF 1.9 3区 地球科学
Journal of Quaternary Science Pub Date : 2024-06-07 DOI: 10.1002/jqs.3627
STEPHANIE A. Tassier-Surine, PHILLIP J. Kerr, SUSAN M. Kilgore, BRADLEY D. Cramer
{"title":"Defining the Sheldon Creek Formation, a Middle Wisconsinan (MIS 3) till in Iowa, USA","authors":"STEPHANIE A. Tassier-Surine,&nbsp;PHILLIP J. Kerr,&nbsp;SUSAN M. Kilgore,&nbsp;BRADLEY D. Cramer","doi":"10.1002/jqs.3627","DOIUrl":"10.1002/jqs.3627","url":null,"abstract":"<p>A pre-Late Wisconsinan, post-Illinoian, till sheet has long been recognized in north-central Iowa, but has not been formally recognized or defined until now. Early researchers referred to these deposits as the ‘Tazewell’, and the term ‘Sheldon Creek’ was more recently used informally by the Iowa Geological Survey in guidebooks and reports. Recent mapping has extended the eastern margin significantly past previous interpretations. The Sheldon Creek Formation has similar lithologic characteristics to the overlying Alden Member of the Dows Formation, and the two units are distinguished mainly by stratigraphic position. Differentiation from underlying Pre-Illinoian till units is accomplished using lithology, primarily matrix grain-size and sand fraction lithology. A suite of 22 radiocarbon ages indicate two distinct, separate groupings within the Sheldon Creek data. These data strongly suggest ice advanced south to 42° N twice, once during Marine Isotope Stage (MIS) 3 and again during late MIS 3 or possibly early MIS 2. The presence of the Laurentide Ice Sheet in northern Iowa during MIS 3 has significant implications for ice sheet reconstructions during this interval.</p>","PeriodicalId":16929,"journal":{"name":"Journal of Quaternary Science","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jqs.3627","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141370870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The onset of Pliocene–Early Pleistocene fluvial aggradation in the Southeastern Alpine Foreland (Velenje Basin, Slovenia) and its paleoenvironmental implications 东南阿尔卑斯山前陆(斯洛文尼亚维伦耶盆地)上新世-早更新世河道侵蚀的开始及其对古环境的影响
IF 1.9 3区 地球科学
Journal of Quaternary Science Pub Date : 2024-05-17 DOI: 10.1002/jqs.3623
Eva Mencin Gale, Petra Jamšek Rupnik, Naki Akçar, Marcus Christl, Christof Vockenhuber, Flavio S. Anselmetti, Andrej Šmuc
{"title":"The onset of Pliocene–Early Pleistocene fluvial aggradation in the Southeastern Alpine Foreland (Velenje Basin, Slovenia) and its paleoenvironmental implications","authors":"Eva Mencin Gale,&nbsp;Petra Jamšek Rupnik,&nbsp;Naki Akçar,&nbsp;Marcus Christl,&nbsp;Christof Vockenhuber,&nbsp;Flavio S. Anselmetti,&nbsp;Andrej Šmuc","doi":"10.1002/jqs.3623","DOIUrl":"10.1002/jqs.3623","url":null,"abstract":"<p>In this study, we focused on the Pliocene–Early Pleistocene fluvial terraces in the Velenje Basin and reconstructed the morphostratigraphy, sedimentary depositional environment, provenance and age of the gravel deposits using geomorphological, sedimentological, petrographic and chronological analyses. Geomorphological mapping revealed the presence of two main river-terrace groups. The terraces in the older terrace group are severely degraded and preserved only as remnants capping high ground, while in contrast the younger group is better preserved. Detailed lithofacies analyses of four selected stratigraphic sections of the older terrace group show that the gravel was deposited in a meandering and wandering environment. The gravel consists of metamorphic, igneous, volcaniclastic, clastic and carbonate lithologies derived from the north, east and west from the Paka River catchments. To determine the timing of deposition, we performed isochron-burial dating using cosmogenic <sup>26</sup>Al and <sup>10</sup>Be. Our new age constraints date the deposition of the older terrace group to 2.7 ± 0.3 Ma. Establishing the aggradation and incision model of the Velenje Basin documents pronounced regional tectonic uplift during the Pliocene–Early Pleistocene, which led to incision and the subsequent formation of a terrace staircase.</p>","PeriodicalId":16929,"journal":{"name":"Journal of Quaternary Science","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jqs.3623","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140964753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Holocene geoecohydrological floodplain dynamics in NE Belgium: regional drivers of local change 比利时东北部全新世地质-水文洪泛动态:地方变化的区域驱动因素
IF 1.9 3区 地球科学
Journal of Quaternary Science Pub Date : 2024-05-17 DOI: 10.1002/jqs.3621
Renske Hoevers, Nils Broothaerts, Gert Verstraeten
{"title":"Holocene geoecohydrological floodplain dynamics in NE Belgium: regional drivers of local change","authors":"Renske Hoevers,&nbsp;Nils Broothaerts,&nbsp;Gert Verstraeten","doi":"10.1002/jqs.3621","DOIUrl":"10.1002/jqs.3621","url":null,"abstract":"<div>\u0000 \u0000 <p>During the Late Holocene, the majority of lowland river systems in temperate Europe transformed from low-energy multi-channel rivers in strongly vegetated marshy floodplains to more open floodplains characterised by single-channel meandering rivers with overbank deposits. While the general framework of this transformation in floodplain geomorphology, ecology and hydrology (i.e. geoecohydrology) is widely recognised many uncertainties remain as its timing varies significantly, both among different river catchments and within them. To unravel whether the observed differences in floodplain response can be attributed to differences in the timing and nature of the driving forces or to a difference in sensitivity towards them, we compare long-term and large-scale reconstructions of the geoecohydrological floodplain dynamics and of the (climatically and anthropogenically driven) land cover change for two contrasting regions: the central Belgian loess belt and the sandy Campine region. By using a combination of cluster analysis, ordination and Ellenberg indicator scores on a large multi-proxy and multi-site dataset, we revealed the major trends in the past geoecohydrological evolution of northeastern Belgian floodplains. These trends are probably determined by changes in floodplain wetness, which can in turn be linked to variations in upland forest cover. The Early and Late Holocene floodplain transformations appear synchronous with the respective increases and decreases in upland forest cover in the vicinity of the sites, largely determining the water availability in the river catchments and thereby their local geoecohydrological conditions. Initially, these evolutions were determined by climate, but during the Middle and especially Late Holocene anthropogenic influence became a far more important factor, causing the evolutions in the two studied regions to increasingly diverge. While marshy floodplains with forested margins can still be found in the sandy Campine region today, these have become rare in the central Belgian loess belt due to the combination of a higher level of human impact and greater erodibility of the soils in this area. Despite the strong spatiotemporal variability of the floodplain transformations, we observe a trend towards increasingly rapid floodplain responses to upland land cover changes over the course of the Holocene, probably related to the growing hillslope–floodplain connectivity. We conclude that the (dis)similarities in Holocene geoecohydrological floodplain change can be largely attributed to the (dis)similarities in (climatically or anthropogenically driven) land cover change in the uplands, although the differences in inherent sensitivity of the locations – linked to factors such as soil type and topography – further complicate the already non-linear impact–response relationships.</p>\u0000 </div>","PeriodicalId":16929,"journal":{"name":"Journal of Quaternary Science","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140962215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Potential historically intertropical stable areas during the Late Quaternary of South America 南美洲第四纪晚期历史上潜在的热带间稳定地区
IF 2.3 3区 地球科学
Journal of Quaternary Science Pub Date : 2024-05-15 DOI: 10.1002/jqs.3624
Mário André Trindade Dantas, Thais Rabito Pansani, Lidiane Asevedo, Thaísa Araújo, Lucas de Melo França, Wilcilene Santos de Aragão, Franciely da Silva Santos, Elisa Cravo, Felipe Rodrigues Waldherr, Celso Lira Ximenes
{"title":"Potential historically intertropical stable areas during the Late Quaternary of South America","authors":"Mário André Trindade Dantas, Thais Rabito Pansani, Lidiane Asevedo, Thaísa Araújo, Lucas de Melo França, Wilcilene Santos de Aragão, Franciely da Silva Santos, Elisa Cravo, Felipe Rodrigues Waldherr, Celso Lira Ximenes","doi":"10.1002/jqs.3624","DOIUrl":"https://doi.org/10.1002/jqs.3624","url":null,"abstract":"South America is a pivotal paleontological setting for Late Quaternary megafaunal research. Nonetheless, its paleobiogeography and paleoecology, and the causes for the recent extinction of megafauna in the Late Pleistocene/Early Holocene are not yet fully understood. This study aimed to investigate the potential geographical distribution and historically intertropical stable areas (HISAs) of South American megafauna. We generated maps using Paleo‐Species Distribution Models for 12 megafaunal taxa (11 herbivores and one carnivore) during interglacial and glacial periods in the Late Quaternary: 120 and 21 ka. Our models, together with isotopic data, show that the HSIAs occurred mainly in low‐altitude plains (<1000 m) and were superimposed on seasonal dry forest biomes. We propose the occurrence of two HSIAs: the West Intertropical Region and the Brazilian Intertropical Region, the latter being redefined. We suggest that the Brazilian Intertropical Region is much smaller than previously proposed, but was still a key zoogeographical region for megafauna in South America during the Late Pleistocene.","PeriodicalId":16929,"journal":{"name":"Journal of Quaternary Science","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140975137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The preservation of storm events in the geologic record of New Jersey, USA 美国新泽西州地质记录中风暴事件的保存情况
IF 1.9 3区 地球科学
Journal of Quaternary Science Pub Date : 2024-05-15 DOI: 10.1002/jqs.3622
Kristen M. Joyse, Jennifer S. Walker, Linda Godfrey, Margaret A. Christie, Timothy A. Shaw, D. Reide Corbett, Robert E. Kopp, Benjamin P. Horton
{"title":"The preservation of storm events in the geologic record of New Jersey, USA","authors":"Kristen M. Joyse,&nbsp;Jennifer S. Walker,&nbsp;Linda Godfrey,&nbsp;Margaret A. Christie,&nbsp;Timothy A. Shaw,&nbsp;D. Reide Corbett,&nbsp;Robert E. Kopp,&nbsp;Benjamin P. Horton","doi":"10.1002/jqs.3622","DOIUrl":"10.1002/jqs.3622","url":null,"abstract":"<p>Geologic reconstructions of overwash events can extend storm records beyond the brief instrumental record. However, the return periods of storms calculated from geologic records alone may underestimate the frequency of events given the preservation bias of geologic records. Here, we compare a geologic reconstruction of storm activity from a salt marsh in New Jersey to two neighboring instrumental records at the Sandy Hook and Battery tide gauges. Eight overwash deposits were identified within the marsh's stratigraphy by their fan-shaped morphology and coarser mean grain size (3.6 ± 0.7 φ) compared to autochthonous sediments they were embedded in (5.6 ± 0.8 φ). We used an age–depth model based on modern chronohorizons and three radiocarbon dates to provide age constraints for the overwash deposits. Seven of the overwash deposits were attributed to historical storms, including the youngest overwash deposit from Hurricane Sandy in 2012. The four youngest overwash deposits overlap with instrumental records. In contrast, the Sandy Hook and Battery tide gauges recorded eight and 11 extreme water levels above the 10% annual expected probability (AEP) of exceedance level, respectively, between 1932/1920 and the present. The geologic record in northern New Jersey, therefore, has a 36–50% preservation potential of capturing extreme water levels above the 10% AEP level.</p>","PeriodicalId":16929,"journal":{"name":"Journal of Quaternary Science","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jqs.3622","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140972082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Stratigraphy and OSL chronology of the Middle–Upper Pleistocene sedimentary sequence and vegetation history during Late MIS6–MIS5e in the Neva Lowland (St. Petersburg region, Russia) 涅瓦低地(俄罗斯圣彼得堡地区)中-上更新世沉积序列的地层学和OSL年代学以及晚MIS6-MIS5e期间的植被史
IF 1.9 3区 地球科学
Journal of Quaternary Science Pub Date : 2024-04-24 DOI: 10.1002/jqs.3618
Maksim V. Ruchkin, Ekaterina S. Nosevich, Mikhail V. Sheetov, Dominik Brill
{"title":"Stratigraphy and OSL chronology of the Middle–Upper Pleistocene sedimentary sequence and vegetation history during Late MIS6–MIS5e in the Neva Lowland (St. Petersburg region, Russia)","authors":"Maksim V. Ruchkin,&nbsp;Ekaterina S. Nosevich,&nbsp;Mikhail V. Sheetov,&nbsp;Dominik Brill","doi":"10.1002/jqs.3618","DOIUrl":"10.1002/jqs.3618","url":null,"abstract":"<div>\u0000 \u0000 <p>The quarry of the Sverdlov (Etalon) Factory stands out as a unique site in the northwest of the East European Plain since it exposes an almost complete Upper Pleistocene stratigraphic succession. Previous investigations have revealed a sequence of marine sediments deposited during the whole Mikulino Interglacial [Eemian, Marine Isotope Stage (MIS)5e], but the chronology of the Late Pleistocene deposits remains incomplete and requires further update. We present a study of the Middle–Upper Pleistocene units exposed in the Sverdlov Factory quarry by using geological methods, optically stimulated luminescence (OSL) dating and pollen analysis. The lower part of the Sverdlov Factory section comprises glaciomarine/glaciolacustrine varves, which accumulated during degradation of the Late Moscow (Late Saalian, Late MIS6) glaciation and correspond to pollen zone M<sub>1</sub> (lower peak of <i>Picea</i>). They are covered by interglacial marine clayey silt that includes all Mikulino regional pollen zones M<sub>2</sub>–M<sub>8</sub>. According to a Bayesian model based on K-rich feldspar luminescence ages, the interglacial marine deposition started 133 ± 8 ka ago and ended 109 ± 7 ka ago. The marine sediments are overlain by lacustrine silt with a K-rich feldspar age of 119 ± 7 ka, lacustrine/alluvial sand with plant detritus formed 47–41 ka ago, and lacustrine sand and silt without organic matter accumulated ~39 ka ago. The upper part of the section is composed of subglacial till formed during the Late Valdai (Late Weichselian, MIS2) under the Scandinavian Ice Sheet and glaciolacustrine varved deposits of the Baltic Ice Lake. Two ages were acquired using quartz OSL from these varves, 16.9 ± 1.6 and 15.7 ± 1.0 ka, which are assumed to slightly overestimate the true age.</p>\u0000 </div>","PeriodicalId":16929,"journal":{"name":"Journal of Quaternary Science","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140660635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Mineral magnetism and palaeoenvironment recorded in loess in southern England 英格兰南部黄土中记录的矿物磁性和古环境
IF 1.9 3区 地球科学
Journal of Quaternary Science Pub Date : 2024-04-22 DOI: 10.1002/jqs.3620
Dominika Niezabitowska, Thomas Stevens, Balázs Bradák, Martin Chadima, Yunus Baykal, Daniele Sechi, Ramona Schneider
{"title":"Mineral magnetism and palaeoenvironment recorded in loess in southern England","authors":"Dominika Niezabitowska,&nbsp;Thomas Stevens,&nbsp;Balázs Bradák,&nbsp;Martin Chadima,&nbsp;Yunus Baykal,&nbsp;Daniele Sechi,&nbsp;Ramona Schneider","doi":"10.1002/jqs.3620","DOIUrl":"10.1002/jqs.3620","url":null,"abstract":"<p>Extensive research has focused on the loess deposits in southern England, aiming to unravel their stratigraphic and palaeoenvironmental significance. However, no systematic mineral magnetic study on these deposits has yet been undertaken. Here we address this by investigating the magnetic mineral composition and alignment of loess at two sites in southern England, Lowland Point (LP) on the Lizard Peninsula of Cornwall, and Pegwell Bay (PB) in eastern Kent on the Isle of Thanet. A set of rock magnetic analyses was conducted to understand mineral magnetism within the studied sections. In addition, the primary depositional origin of the magnetic fabrics as well as their overprinting caused by various possible post-depositional processes were examined through anisotropy of magnetic susceptibility (AMS). The magnetic mineral composition is similar at both sites, derived from both sedimentary (aeolian) and post-depositional processes. The AMS results show magnetic foliation that varies between the two sites, aligning with the bedding plane, indicating deposition from gravitational dust fall at the PB site, and a stronger wind transport energy at the LP site. Although the magnetic lineation of bulk AMS is relatively weak, there is a noticeable tendency towards alignment in most samples, with flow directions from the SE indicated at both sections if a strong wind is assumed at LP, although with a possible SW direction if a weaker wind is assumed. These observations may imply the preservation of palaeowind directions during dust transport, with a substantial southerly component, which contradicts previous assertions of dominant northerly or northeasterly winds. Indeed, a possible dominant southeasterly wind direction between 25 and 18 ka would suggest a limited influence of katabatic, westerly or polar northeasterly winds during dust transport, and rather may imply the effect of low-pressure systems passing through the English Channel during that period.</p>","PeriodicalId":16929,"journal":{"name":"Journal of Quaternary Science","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jqs.3620","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140673073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Tephra identification without pre-separation in ashed peat 未经预分离的灰泥炭中的凝灰岩识别
IF 1.9 3区 地球科学
Journal of Quaternary Science Pub Date : 2024-04-04 DOI: 10.1002/jqs.3619
LUCY C. Blennerhassett, PAUL C. Guyett, EMMA L. Tomlinson
{"title":"Tephra identification without pre-separation in ashed peat","authors":"LUCY C. Blennerhassett,&nbsp;PAUL C. Guyett,&nbsp;EMMA L. Tomlinson","doi":"10.1002/jqs.3619","DOIUrl":"10.1002/jqs.3619","url":null,"abstract":"<p>Cryptotephras in peat and sediment samples are traditionally separated for geochemical characterization using chemical or density floatation techniques following initial tephra identification and shard counting through analysis of ashed residue via light microscopy. However, these practices can be time consuming, subject to practitioner experience and material type, with a potential for sample loss. We present an alternative approach to identify cryptotephra in peat and sedimentary samples, where ashed material is mounted directly in epoxy resin and analysed through back-scattered electron (BSE) imaging via scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM-EDX). Semi-quantitative, unsupervised chemical maps of epoxy mounts are created within 120 min using ‘Feature Analysis’ on AZtec software by Oxford Instruments. These maps locate grains of higher atomic mass and categorize phases based on geochemistry. We create a tephra identification method using an ombrotrophic peat sample doped with bimodal Vedde Ash, where recovery of the known tephra proportion in wet peat is 96%. We also propose an automated alternative to optical shard counting, whereby tephra counts identified via Feature Analysis can be ratioed to total grain counts acquired through ImageJ software and extrapolated to the inorganic fraction in wet peat. We apply the method to a minerotrophic peat from Brackloon Wood, Mayo, Ireland, where the Laki <span>ad</span> 1783–84 cryptotephra is successfully identified.</p>","PeriodicalId":16929,"journal":{"name":"Journal of Quaternary Science","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jqs.3619","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140581558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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