Boreas最新文献

{"title":"Beachrock formation influenced by co-seismic deformation and relative sea-level changes during the Holocene near the Gulf of Saros, Türkiye (NE Aegean Sea)","authors":"Ufuk Tari","doi":"10.1111/bor.70035","DOIUrl":"https://doi.org/10.1111/bor.70035","url":null,"abstract":"<p>This study presents the discovery and detailed analysis of the first confirmed beachrock occurrence on the northern coast of the Gelibolu (Gallipoli) Peninsula in the Gulf of Saros, Northeastern Aegean Sea. Despite the dynamic sandy beaches and rugged coastlines along the southern shores of the gulf, clear evidence of historical co-seismic deformation is preserved in both exposed and submerged beachrock formations. The sedimentary fabric and structural characteristics of these deposits provide critical insights into Late Holocene coastal evolution, including relative sea-level (RSL) fluctuations and tectonic activity. By integrating UAV-based aerial mapping, petrographic and multianalytical microspectroscopic techniques, and radiocarbon dating, this study reconstructs distinct phases of shoreline development shaped by both gradual uplift and episodic seismic events. Radiometric dating of undeformed beachrock indicates ages between 1.1 and 13.6 cal. ka BP, whereas younger, seaward-tilted deposits date to 385 cal. a BP, which is consistent with historical records of the AD 1756 earthquake. After correcting for the local uplift rate (0.76 mm a⁻¹), the data reveal that the RSL decreases by around −0.30 m, aligning with regional Holocene sea-level trends and reinforcing the tectonic context of the Gelibolu Peninsula within a transform-dominated setting. UAV mapping also revealed fracture patterns orthogonal to the North Anatolian Fault (NAF) stress field, supporting links to past seismic events, including the AD 1766 doublet. This study highlights the value of beachrocks as precise geological archives of coastal deformation and sea-level change. Their structural and chronological characteristics refine regional palaeoseismic models and offer a valuable framework for interpreting older or undocumented seismic events along the NAF in the Northeastern Aegean.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"55 1","pages":"231-257"},"PeriodicalIF":2.9,"publicationDate":"2025-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.70035","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146148197","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}

{"title":"Use of LiDAR to derive a new model of glacial hydro-dynamic events shaping southern Ontario landscapes, Canada","authors":"David R. Sharpe,&nbsp;Chris C. Smart","doi":"10.1111/bor.70025","DOIUrl":"https://doi.org/10.1111/bor.70025","url":null,"abstract":"<p>Examination of a streamlined flow tract in southern Ontario, Canada using LiDAR-based terrain mapping reveals a landscape that was extensively scoured by ice-constrained subglacial meltwater. Multiple scours and channels without related sediment fans/deltas are eroded into carbonate uplands at the Shield-Palaeozoic margin. Erosion extended across the highest uplands, flanks and lowlands with inset eskers, resulting in a streamlined landscape covered with rounded boulders. Palaeozoic carbonate escarpments reveal rock quarrying on stoss and lee sides, likely indicating ice plucking, load deformation and hydraulic fracture. Meltwater overtopping uplands implies ice lifting off the bed, then re-grounding as flow waned. The widespread erosion, overtopping and presence of boulder lags are indicative of vigorous meltwater scouring of ~10 m of till from carbonate uplands, leaving smooth drumlinized surfaces, scoured by sheetflow and possible ice drag. Rough terrain is inferred to have been meltwater scoured into a series of remnant landforms: poorly defined irregular ridges, scour pits and hummocks, which alternatively possibly resulted from ice deformation and melt-out. We speculate that rough terrain resulted from pressurized, turbulent flow during progressive, rapid ice sheet closure and ice contact. Erosional landscapes upflow near the Palaeozoic margin can be correlated downflow through the Peterborough drumlin field to well-documented channel incision and infill sediments beneath Oak Ridges Moraine (ORM), linked by a regional unconformity. A plausible sequence of events includes erosion of a regional unconformity and a complex series of related events that include meltwater flow, ice floatation, then closure, with combined pressurized scour, deformation, ice/hydraulic erosion and later stagnation. Similar to Icelandic jökulhlaups, flooding likely lasted days/weeks such that eroded uplands formed rapidly (&lt;1-year) followed by matching &lt;1 year deposition (~10–50 m gravel-sand-rhythmite fining upward sequence), documented downflow in subglacial channels beneath ORM. Our results suggest a model of sheet flow progressing to channelized flow for meltwater discharge could be considered elsewhere.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"54 4","pages":"590-624"},"PeriodicalIF":2.9,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.70025","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145341705","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}

{"title":"Automated X-ray computed tomography-based analysis of clast fabric in drill-cores of glacial diamicts using deep learning models","authors":"Bennet Schuster,&nbsp;David Mair,&nbsp;Timothy C. Schmid,&nbsp;Lukas Gegg,&nbsp;Marius W. Büchi,&nbsp;Sebastian Schaller,&nbsp;Flavio S. Anselmetti,&nbsp;Frank Preusser","doi":"10.1111/bor.70023","DOIUrl":"https://doi.org/10.1111/bor.70023","url":null,"abstract":"<p>Clast-fabric analysis is a widely used method for investigating depositional and deformation processes in glacial sediments. However, traditional field-based approaches lack standardization, are time consuming and introduce sampling bias. This study aimed to develop a novel approach to automate clast-fabric analysis using machine learning-based image segmentation applied on X-ray computed tomography scanned drill-cores. By retraining a deep neural network and integrating it into state-of-the-art image-segmentation software, we establish a scalable and adaptable workflow for the analysis of sedimentary samples. This included the following: (i) clast segmentation, (ii) object-based analysis, and (iii) fabric analysis. We demonstrate this on drill-core samples of glacial diamicts (tills), achieving performance comparable to leading segmentation models used in geological sciences. We further use this automated workflow to identify grain size-dependent small-scale fabric variations, demonstrating the advantages of deep learning over conventional methods. This workflow provides a foundation for future applications, such as long, continuous drilled sections and field samples, including fluvial and colluvial sediments.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"55 1","pages":"57-72"},"PeriodicalIF":2.9,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.70023","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146148007","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}

{"title":"Living on the edge: Pleistocene ice-free refugia and collared lemming (Dicrostonyx sp.) in the North American High Arctic","authors":"Louis Arbez,&nbsp;Aurelien Royer,&nbsp;Oliver Gilg,&nbsp;Benjamin Pohl,&nbsp;Jean-François Buoncristiani,&nbsp;Sophie Montuire","doi":"10.1111/bor.70026","DOIUrl":"https://doi.org/10.1111/bor.70026","url":null,"abstract":"<p>Collared lemmings (genus <i>Dicrostonyx</i>) are an emblematic group of Arctic-tundra mammalian communities, comprising six different species in North America. As other northern fauna, most of their diversity is impacted by Pleistocene glacial–interglacial cycles. While <i>D. hudsonius</i> and <i>D. richardsoni</i> have a restricted distribution area on both sides of the Hudson Bay, <i>D. groenlandicus</i> is widespread in all Nearctic northernmost regions, from Alaska and Canadian mainland to the High Arctic Archipelago and Greenland, occupying a highly fragmented area. Using extensive data, this paper investigates the morphological variability of the molar of Nearctic <i>Dicrostonyx</i> using geometric morphometrics. Our results show weak interspecific differences among Nearctic <i>Dicrostonyx</i>, while demonstrating the existence of a clear geographical structure: a north–south gradient that structures collared lemming's phenotype, surpassing interspecific differences. The possible causes of such patterns are explored, whether they are environmental (e.g. due to local to regional climatic conditions) or phylogeographic (e.g. isolation of the populations during the glacial periods) using ERA5-Land reconstruction climatic data, and a reconstruction of the Laurentide Ice Sheet extent with isometric variations. The peculiar status of several populations, including Greenland and Victoria Island specimens, can be linked with their survival and isolation in Pleistocene ice-free refugia in the High Arctic in agreement with both genetic and morphological signals. We argue that studying present-day morphological variability can provide meaningful information on the Quaternary biogeography of modern species.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"55 1","pages":"216-230"},"PeriodicalIF":2.9,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.70026","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146139469","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}

{"title":"Shoreline and deglaciation chronology in southeast Norway","authors":"Anders Romundset,&nbsp;Isak Roalkvam,&nbsp;Mikis van Boeckel,&nbsp;Fredrik Høgaas,&nbsp;Kari E. Henningsmoen,&nbsp;Helge I. Høeg,&nbsp;Rolf Sørensen","doi":"10.1111/bor.70024","DOIUrl":"https://doi.org/10.1111/bor.70024","url":null,"abstract":"<p>The postglacial relative sea level history is reconstructed in four areas of mid- and inner Oslofjorden in southeast Norway. The reconstructions are based on radiocarbon-dated raised shoreline levels from 42 sites, mainly isolation basins, and limiting ages from four lakes above the marine limit. All localities are located inside the Younger Dryas Ra moraine and experienced high rates of glacio-isostatic crustal uplift since deglaciation, by far outpacing the eustatic sea level rise and resulting in continuous regional shoreline regression up until today. A postglacial shoreline diagram is constructed, which can be used to derive relative sea-level curves and to date raised shoreline elevations along the fjord. Reconstruction of shoreline isobases within the study area show that their orientation has shifted more than 60° from the deglaciation until present. The shift has been accounted for in the shoreline reconstructions and is likely showing that the initial postglacial uplift was largely influenced by the geometry and load of the Younger Dryas ice sheet in south Norway. We use the tilt of the oldest, well-dated shoreline levels to date a series of substages during northwards ice margin recession in southeast Norway. The results show that the ice margin retreated from the Ra moraine around 11.6 ka and provide the following ages for subsequent substages: Ås 11.45 ka, Ski 11.4 ka, Aker 11.25 ka, Hauerseter 10.9 ka, Dal 10.8 ka and Minnesund 10.6 ka. The deglaciation and shoreline chronologies are combined to produce regional palaeogeographical maps covering stages of deglaciation and land emergence.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"55 1","pages":"29-56"},"PeriodicalIF":2.9,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.70024","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146139285","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}

{"title":"Morphology and sedimentology of murtooized terrain on the southern Fraser Plateau, British Columbia, Canada","authors":"Alexander D. Sodeman,&nbsp;Tracy A. Brennand","doi":"10.1111/bor.70027","DOIUrl":"https://doi.org/10.1111/bor.70027","url":null,"abstract":"<p>Recent public releases of Light Detection and Ranging (LiDAR) data in south central British Columbia (BC), Canada have revealed several landforms resembling ‘murtoos’, previously identified across portions of Scandinavia. In this study, we investigate the morphology and sedimentology of these landforms, the first report of their kind associated with the Cordilleran Ice Sheet (CIS). From remote observations using LiDAR data, we determined that these landforms do not fit the classification scheme of murtoos used by previous authors, and based on our own observations, we use the term ‘murtooized terrain’, due to their superficial similarities with Scandinavian murtoos. Murtooized terrain consists of 1–8 m high, distinctly steep slopes that can continue laterally up to 2 km, changing in orientation along their lateral lengths, creating angular, zig-zag patterns. It can present as dense, subparallel groupings of slopes giving a washboard appearance. Murtooized terrain occurs in several landscape associations including till plains, ribbed terrain, isolated plateaus and near meltwater corridors. Murtooized terrain in association with till plains and ribbed terrains exhibits distinct hill-hole pairs. It typically consists of diamicton interpreted as a regional till sheet winnowed by persistent subglacial groundwater flow, sometimes overlain by melt-out till and covered with a surface veneer of silt and very fine sand interpreted as loess. Massive sand deposited by postglacial overland flows can fill small troughs at the foot of murtooized terrain slopes. The following event sequence explains the formation of murtooized terrain. The concentration of subglacial groundwater flow through very broad topographic troughs winnowed till and resulted in strong ice-bed coupling through basal ice regelation. Following channelized subglacial floods (underbursts) associated with the formation of large (Chasm and Green Lake) meltwater corridors, the CIS underwent collapse and ice surface slopes were reorganized in the adjacent region. Murtooized terrain formed due to widespread, short-term, glaciotectonism associated with this reorganization where the ice and bed were well coupled. Zig-zag slopes and hill-hole pairs are attributed to spatial variations in coupling. Stagnation followed forming melt-out till and crevasse fill ridges. This hypothesis is distinctly different from those developed for the Scandinavian murtoos, suggesting either that the superficial similarities between BC murtooized terrain and Scandinavian murtoos are the products of formational equifinality or that the BC murtooized terrain is a distinct landform.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"54 4","pages":"625-648"},"PeriodicalIF":2.9,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.70027","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145341663","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}

{"title":"Hydroclimatic development from the Early Holocene to anthropogenic times: a comparative study of diatom oxygen isotope records and multiproxy data from Lake Khamra, eastern Siberia","authors":"Amelie Stieg,&nbsp;Boris K. Biskaborn,&nbsp;Ulrike Herzschuh,&nbsp;Jens Strauss,&nbsp;Svetlana S. Kostrova,&nbsp;Luidmila A. Pestryakova,&nbsp;Hanno Meyer","doi":"10.1111/bor.70022","DOIUrl":"https://doi.org/10.1111/bor.70022","url":null,"abstract":"<p>Northern Eurasia underwent major hydroclimatic changes since the beginning of the Holocene interglacial. A rapid warming period reaching the Holocene Thermal Maximum (HTM), followed by a general cooling trend until recent times, was observed in Eurasian lacustrine diatom oxygen isotope (δ¹⁸O_diatom) records. In this study, we present a new Holocene δ¹⁸O_diatom record from Lake Khamra (59.99°N, 112.98°E, Siberia). Our record aligns with Holocene δ¹⁸O_diatom records across the Northern Hemisphere, showing a general millennial-scale cooling trend following an initial maximum at 11.2 cal. ka BP and a second maximum at 6.7 cal. ka BP. These maxima correspond to the summer insolation maximum and elevated Northern Hemisphere air temperatures, as well as increased bioproductivity. Variability on centennial scales is likely driven by precipitation changes, which coincide with higher sedimentation rates and overlay the general decreasing trend throughout the Holocene. In addition, we compared two multiproxy datasets with decadal resolution from Lake Khamra, including δ¹⁸O_diatom data and biogeochemical proxies such as total organic carbon (TOC), total nitrogen (TN), stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopes, and total mercury (THg). The datasets cover a ~210-year period (<i>c</i>. 6.140–6.350 cal. ka BP) at the end of the HTM and a recently published ~220-year record (<i>c</i>. 1790–2015 CE) that embraces the anthropogenic times. The comparison of these two warm phases reveals distinct differences in both the absolute values and the variability of the records. Regarding the δ¹⁸O_diatom data, the recent period shows a nearly threefold increase in range and double the standard deviation, suggesting greater hydroclimatic variability compared to the end of the HTM. Notably, THg levels indicate a sharp increase in recent decades, while δ¹³C declined, contrasting with the observations at the end of the HTM. We attribute these observations partially to far-reaching anthropogenic effects on remote lake systems.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"54 3","pages":"447-467"},"PeriodicalIF":2.4,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.70022","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144647742","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}

{"title":"Processes and Palaeo-Environmental Changes in the Arctic from Past to Present (PalaeoArc) – introduction","authors":"Astrid Lyså,&nbsp;Ívar Ö. Benediktsson,&nbsp;Nicolaj K. Larsen,&nbsp;Juliane Müller,&nbsp;Matt O'Regan","doi":"10.1111/bor.70021","DOIUrl":"https://doi.org/10.1111/bor.70021","url":null,"abstract":"&lt;p&gt;PalaeoArc (Processes and Palaeo-Environmental Changes in the Arctic: from Past to Present) is an international research network dedicated to understanding and explaining climate-driven environmental changes in the Arctic from the Early Pleistocene to the present day. This initiative builds upon a strong foundation of previous palaeo-Arctic research programmes dating back to the 1980s.&lt;/p&gt;&lt;p&gt;The legacy began with the Polar North Atlantic Margins – Late Cenozoic Evolution project (PONAM: 1990–1994; Hjort &amp; Persson &lt;span&gt;1994&lt;/span&gt;; Landvik &amp; Salvigsen &lt;span&gt;1995&lt;/span&gt;; Elverhøi &lt;i&gt;et al&lt;/i&gt;. &lt;span&gt;1998&lt;/span&gt;), followed by the Quaternary Environment of the Eurasian North project (QUEEN: 1996–2002) (Larsen &lt;i&gt;et al&lt;/i&gt;. &lt;span&gt;1999&lt;/span&gt;; Thiede &lt;i&gt;et al&lt;/i&gt;. &lt;span&gt;2001&lt;/span&gt;, &lt;span&gt;2004&lt;/span&gt;; Kjær &lt;i&gt;et al&lt;/i&gt;. &lt;span&gt;2006&lt;/span&gt;). These efforts were succeeded by the Arctic Palaeoclimate and its Extremes programme (APEX: 2004–2012) (Jakobsson &lt;i&gt;et al&lt;/i&gt;. &lt;span&gt;2008&lt;/span&gt;, &lt;span&gt;2010&lt;/span&gt;, &lt;span&gt;2014&lt;/span&gt;) and the Palaeo-Arctic Spatial and Temporal Gateways programme (PAST Gateways: 2012–2018) (Ó Cofaigh &lt;i&gt;et al&lt;/i&gt;. &lt;span&gt;2016&lt;/span&gt;, &lt;span&gt;2018&lt;/span&gt;).&lt;/p&gt;&lt;p&gt;The current network of PalaeoArc was launched in 2019, where a new international steering committee was formed to lead activities, annual conferences and field trips from 2019 to 2025. The first meeting took place in Poznań, Poland (2019) (Lyså &lt;i&gt;et al&lt;/i&gt;. &lt;span&gt;2019&lt;/span&gt;). A second conference, originally planned for 2020 in Pisa, was postponed due to the COVID-19 pandemic and held online in 2021. A PalaeoArc paper collection in &lt;i&gt;Arctic Antarctic and Alpine Research&lt;/i&gt; (Lyså &lt;i&gt;et al&lt;/i&gt;. &lt;span&gt;2022&lt;/span&gt;) originates from that conference and reflects the network's broad scientific scope, fostering interdisciplinary discussions on Arctic environmental change across a range of timescales. The third PalaeoArc conference was held in Rovaniemi, Finland, in 2022, and some papers from the conference were published in Bulletin of The Geological Society of Finland (Sarala &lt;span&gt;2023&lt;/span&gt;). Thereafter, conferences were held in Akureyri, Iceland (2023) and Stockholm, Sweden (2024), from which the articles in this special issue originate. The final PalaeoArc conference is scheduled to take place in Tromsø, Norway, in 2025.&lt;/p&gt;&lt;p&gt;The Arctic is experiencing some of the fastest and most dramatic impacts of global warming, with surface air temperatures rising nearly four times faster than the global average between 1979 and 2021 (Rantanen &lt;i&gt;et al&lt;/i&gt;. &lt;span&gt;2022&lt;/span&gt;). Even if global temperature increases are kept below 2 °C, the region is expected to undergo profound and lasting changes such as loss of sea- and glacial ice, permafrost thaw and shifts in precipitation patterns (AMAP &lt;span&gt;2017&lt;/span&gt;; Fox-Kemper &lt;span&gt;2021&lt;/span&gt;).&lt;/p&gt;&lt;p&gt;To understand these changes and their complex feedback mechanisms, long-term palaeorecords are essential. They offer critical context for","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"54 3","pages":"284-287"},"PeriodicalIF":2.4,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.70021","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144647554","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}

{"title":"Food web reconstruction of Barmaky, the oldest post-LGM hunter-gatherer site in north-western Ukraine","authors":"Lilian Reiss,&nbsp;Kerstin Pasda,&nbsp;Christoph Mayr,&nbsp;Patrick Ludwig,&nbsp;Laura Stiller,&nbsp;Victor Chabai,&nbsp;Andreas Maier","doi":"10.1111/bor.70018","DOIUrl":"https://doi.org/10.1111/bor.70018","url":null,"abstract":"<p>The site of Barmaky currently marks the oldest Epigravettian occupation of north-western Ukraine shortly after the Last Glacial Maximum (LGM), dated to around 19 cal. ka BP. Stable isotope analyses of bone collagen from six terrestrial mammals and two bird species show a comparatively highly structured palaeo-food web. Characteristic are high δ¹⁵N values in mammoth (<i>Mammuthus primigenius</i>) bone collagen compared with other herbivores and δ¹³C values showing niche partitioning between mammoth and hare on the one hand and reindeer on the other. These findings may indicate differentiated herbivore niches, with different diets and habitats between herbivorous groups. Additionally, different mobility patterns could cause isotopic scatter in food webs. To better understand the context of early post-LGM mammoth behaviour, we compare the mammoth δ¹⁵N values of Barmaky (19.0 cal. ka BP; 7.2±0.1‰) with those of Yudinovo (lower layer: 19.1/18.3–15.1 cal. ka BP and upper layer: 14.8–13.8 cal. ka BP; 7.3±1.0‰), Yeliseevichi (17.6 cal. ka BP; 5.7±0.8‰) and Mezhyrich (18.5–17.5 cal. ka BP; 4.3±0.8‰). At all sites, δ¹⁵N values of mammoths are comparatively high, except for Mezhyrich and a single specimen from Barmaky. In comparison with sedentary hares, mammoths from Barmaky suggest a non-locally dominated δ¹⁵N signal, while the mammoths from Mezhyrich show the local isotope signal. We also discuss the potential role of differences in temperature, precipitation and permafrost development for the different locations. Results from climate models indicate a gradient in temperature and precipitation with possible implications for food availability in the mammoth steppe.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"55 1","pages":"182-197"},"PeriodicalIF":2.9,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.70018","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146136409","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}

{"title":"Combining morphological and molecular data to study past foraminiferal communities from a temperate coastal sediment core","authors":"Meryem Mojtahid,&nbsp;Magali Schweizer,&nbsp;Damien Le Moigne,&nbsp;Gwendoline Grégoire,&nbsp;Anne Murat,&nbsp;Isabelle Poirier,&nbsp;Agnès Baltzer,&nbsp;Inge van Dijk,&nbsp;Marie-Christine Morère-Le Paven,&nbsp;Martin Bourges,&nbsp;Maria Pia Nardelli,&nbsp;Christine Barras,&nbsp;Edouard Metzger,&nbsp;Aurelia Mouret","doi":"10.1111/bor.70020","DOIUrl":"https://doi.org/10.1111/bor.70020","url":null,"abstract":"<p>This paper presents the results of a dual approach for assessing fossil benthic foraminiferal communities using both traditional morphology-based analyses and sedimentary ancient DNA (<i>seda</i>DNA) metabarcoding. The main objectives are to test the feasibility of <i>seda</i>DNA analyses to assess foraminiferal biodiversity in temperate shelf sediments (Le Croisic, France) off a major river system through time (Mid- to Late Holocene), and to point out the similarities and differences between classical and molecular methods. Our results show that, in contrast to the high foraminiferal diversity obtained from classic morphological analysis (over 140 taxa), the <i>seda</i>DNA analysis yielded only 20 operational taxonomic units (OTUs), which can be considered as equivalent to species. This strongly suggests a bad preservation of foraminiferal DNA downcore, likely due to the relatively ‘high’ temperature of the study site (14 °C) and/or to a methodological bias (e.g. insufficient amount of extracted sediment). In the total <i>seda</i>DNA, more than 90% of the reads were assigned to monothalamids (organic-shelled foraminifera). In contrast, only a small number of mineralized taxa, highly dominant when identified using the morphological approach, were detected. This could be due to the naturally higher abundance of monothalamids compared to hard-shelled foraminifera. While this abundance is reflected in <i>seda</i>DNA, it is not preserved in fossil morphological assemblages. In addition, the <i>seda</i>DNA of monothalamids might be easier to extract and their barcode to amplify than hard-shelled foraminifera. The discrepancies between the microfossil data and <i>seda</i>DNA also include several species (e.g. <i>Ammonia confertitesta</i> (T6), <i>Elphidium oceanense</i> (S3), <i>Nonionella</i> sp. T4 and <i>Nonionella</i> sp. T6) that were rarely or not at all found in the fossil material which might be an indication of the presence of propagules, morphologically undetected in the &gt;63 μm size fraction used. Finally, the presence of sequences of <i>A. confertitesta</i> and fossil specimens in the deep layers of the study cores suggests that this species, considered until now as recently invasive on the European coast, could have been present in the Atlantic coast several thousand years ago, much before any anthropogenic activity involving international shipping and commercial trades.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"55 1","pages":"198-215"},"PeriodicalIF":2.9,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.70020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146136316","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}