Boreas最新文献

{"title":"Southern Hemisphere Westerly Winds have modulated the formation of laminations in sediments in Lago Fagnano (Tierra del Fuego, Argentina) over the past 6.3 ka","authors":"Alexis Vizcaino,&nbsp;Francisco J. Jimenez-Espejo,&nbsp;Robert B. Dunbar,&nbsp;David Mucciarone,&nbsp;Antonio García-Alix,&nbsp;Ina Neugebauer,&nbsp;Daniel Ariztegui","doi":"10.1111/bor.12600","DOIUrl":"https://doi.org/10.1111/bor.12600","url":null,"abstract":"<p>Tierra del Fuego in Argentina is a unique location to examine past Holocene wind variability since it intersects the core of the Southern Hemisphere Westerly Winds (SHWW). The SHWW are the most powerful prevailing winds on Earth. Their variation plays a role in regulating atmospheric CO₂ levels and rainfall amounts and distribution, both today and in the past. We obtained a piston core (LF06-PC8) from Bahía Grande, a protected sub-basin at the southern margin of Lago Fagnano, the largest lake in Tierra del Fuego. This article focuses on the uppermost 185 cm of this core, corresponding to laminated sediment from the last ~6.3 ka. Laminations consist of millimetre-scale paired dark and light layers. Previous studies and new geochemical analysis show that the dark and light layers are characterized by differing concentrations of Mn and Fe. We attribute the distribution of Mn and Fe to episodic hypolimnic oxic–anoxic variations. The age model suggests an approximately bidecadal timescale for the formation of each layer pair. We propose a new model of these redox changes with the SHWW variations. The most likely phenomenon to produce complete water-column mixing is thermobaric instability, which occurs in colder winters with low-intensity SHWW (El Niño-like conditions). In contrast, windier winters are characterized by higher temperatures and reduced mixing in the water column, facilitating a decline in oxygen concentration. Laminations, and the inferred presence of periodic hypolimnion redox changes, are common features of the past ~6.3 ka. Geochemical proxy variability is compatible with an intensification of El Niño/Southern Oscillation activity during the past ~2 ka.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"52 1","pages":"124-138"},"PeriodicalIF":2.2,"publicationDate":"2022-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.12600","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50137526","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":"‘Holocene history of the eastern side of Novaya Zemlya from glaciomarine sediment records in the Tsivol’ki Fjord’: Comments","authors":"Ekaterina Taldenkova","doi":"10.1111/bor.12603","DOIUrl":"10.1111/bor.12603","url":null,"abstract":"<p>Rusakov <i>et al</i>. (<span>2022</span>) present a multiproxy-based reconstruction of the Holocene history of Tsivol’ki Fjord located on the Kara Sea coast of the northern Novaya Zemlya. A considerable portion of the palaeoreconstructions is derived from the data on macro- and microfossils. As an author of these data (although not acknowledged in the paper), I point to several mistakes in the data presentation, argue for a different palaeoenvironmental interpretation of certain fossil assemblages and add new data for the topmost part of the sediment core. Additionally, information on ice- and iceberg-rafted debris (IRD) counts is presented that provides evidence for past variations in the glacier front position and iceberg calving. Altogether, this considerably changes the palaeoenvironmental reconstructions of the Holocene history of Tsivol’ki Fjord as drawn by Rusakov <i>et al</i>. (<span>2022</span>). The revised environmental interpretation is as follows: microfossil data give evidence for a distal position of the glacier front from the studied core site in the outer fjord and a persistent exchange with open sea waters throughout the whole time period since 10.6 cal. ka BP. After the relatively warm Early–Middle Holocene, cooling started that resulted in the offshore glacier advance manifested by the rise in sedimentation rates and strong meltwater influence that were the reason for the drop in the total abundance of microfossils and IRD during 3.6 to 4.6 cal. ka BP. Between 3.6 and 0.9 cal. ka BP, the highest relative abundance of the glacier-distal benthic foraminiferal species <i>Islandiella norcrossi/helenae</i>, the growing total abundance and diversity of microfossils, the decrease in sedimentation rates and the rising IRD content imply the gradual retreat of the glacier front after the short progradation event. The last millennium is characterized by the highest total abundance and diversity of microfossils, low sedimentation rates and benthic foraminiferal assemblages gradually becoming similar to the Early–Middle Holocene ones.</p><p>The lead author of Rusakov <i>et al</i>. (<span>2022</span>) article was invited by <i>Boreas</i> to reply to these comments but we received no response.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"52 1","pages":"139-144"},"PeriodicalIF":2.2,"publicationDate":"2022-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.12603","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47454707","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":"Growth and retreat of the last British–Irish Ice Sheet, 31 000 to 15 000 years ago: the BRITICE-CHRONO reconstruction","authors":"Chris D. Clark,&nbsp;Jeremy C. Ely,&nbsp;Richard C. A. Hindmarsh,&nbsp;Sarah Bradley,&nbsp;Adam Ignéczi,&nbsp;Derek Fabel,&nbsp;Colm Ó Cofaigh,&nbsp;Richard C. Chiverrell,&nbsp;James Scourse,&nbsp;Sara Benetti,&nbsp;Tom Bradwell,&nbsp;David J. A. Evans,&nbsp;David H. Roberts,&nbsp;Matt Burke,&nbsp;S. Louise Callard,&nbsp;Alicia Medialdea,&nbsp;Margot Saher,&nbsp;David Small,&nbsp;Rachel K. Smedley,&nbsp;Edward Gasson,&nbsp;Lauren Gregoire,&nbsp;Niall Gandy,&nbsp;Anna L. C. Hughes,&nbsp;Colin Ballantyne,&nbsp;Mark D. Bateman,&nbsp;Grant R. Bigg,&nbsp;Jenny Doole,&nbsp;Dayton Dove,&nbsp;Geoff A. T. Duller,&nbsp;Geraint T. H. Jenkins,&nbsp;Stephen L. Livingstone,&nbsp;Stephen McCarron,&nbsp;Steve Moreton,&nbsp;David Pollard,&nbsp;Daniel Praeg,&nbsp;Hans Petter Sejrup,&nbsp;Katrien J. J. Van Landeghem,&nbsp;Peter Wilson","doi":"10.1111/bor.12594","DOIUrl":"10.1111/bor.12594","url":null,"abstract":"<p>The BRITICE-CHRONO consortium of researchers undertook a dating programme to constrain the timing of advance, maximum extent and retreat of the British–Irish Ice Sheet between 31 000 and 15 000 years before present. The dating campaign across Ireland and Britain and their continental shelves, and across the North Sea included 1500 days of field investigation yielding 18 000 km of marine geophysical data, 377 cores of sea floor sediments, and geomorphological and stratigraphical information at 121 sites on land; generating 690 new geochronometric ages. These findings are reported in 28 publications including synthesis into eight transect reconstructions. Here we build ice sheet-wide reconstructions consistent with these findings and using retreat patterns and dates for the inter-transect areas. Two reconstructions are presented, a wholly empirical version and a version that combines modelling with the new empirical evidence. Palaeoglaciological maps of ice extent, thickness, velocity, and flow geometry at thousand-year timesteps are presented. The maximum ice volume of 1.8 m sea level equivalent occurred at 23 ka. A larger extent than previously defined is found and widespread advance of ice to the continental shelf break is confirmed during the last glacial. Asynchrony occurred in the timing of maximum extent and onset of retreat, ranging from 30 to 22 ka. The tipping point of deglaciation at 22 ka was triggered by ice stream retreat and saddle collapses. Analysis of retreat rates leads us to accept our hypothesis that the marine-influenced sectors collapsed rapidly. First order controls on ice-sheet demise were glacio-isostatic loading triggering retreat of marine sectors, aided by glaciological instabilities and then climate warming finished off the smaller, terrestrial ice sheet. Overprinted on this signal were second order controls arising from variations in trough topographies and with sector-scale ice geometric readjustments arising from dispositions in the geography of the landscape. These second order controls produced a stepped deglaciation. The retreat of the British–Irish Ice Sheet is now the world’s most well-constrained and a valuable data-rich environment for improving ice-sheet modelling.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"51 4","pages":"699-758"},"PeriodicalIF":2.2,"publicationDate":"2022-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.12594","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41454026","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":"An Early Pleistocene interglacial deposit at Pingorsuit, North-West Greenland","authors":"Ole Bennike,&nbsp;William Colgan,&nbsp;Lars Hedenäs,&nbsp;Oliver Heiri,&nbsp;Geoffrey Lemdahl,&nbsp;Peter Wiberg-Larsen,&nbsp;Sofia Ribeiro,&nbsp;Roberto Pronzato,&nbsp;Renata Manconi,&nbsp;Anders A. Bjørk","doi":"10.1111/bor.12596","DOIUrl":"10.1111/bor.12596","url":null,"abstract":"<p>At the Pingorsuit Glacier in North-West Greenland, an organic-rich deposit that had recently emerged from the retreating ice cap was discovered at an elevation of 480 m above sea level. This paper reports on macrofossil analyses of a coarse detritus gyttja and peaty soil, which occurred beneath a thin cover of till and glacifluvial deposits. The sediments contained remains of vascular plants, mosses, beetles, caddisflies, midges, bryozoans, sponges and other invertebrates. The flora includes black spruce, tree birch, boreal shrubs and wetland and aquatic taxa, which shows that mires, lakes and ponds were present in the area. We describe a new extinct waterwort species <i>Elatine odgaardii</i>. The fossils were deposited in a boreal environment with a mean July air temperature that was at least 9 °C higher than at present. The fossil assemblages show strong similarities with others from Greenland that have been assigned an Early Pleistocene age, and we suggest a similar age for the sediments found at the margin of the Pingorsuit Glacier.</p><p>At the Pingorsuit Glacier in North-West Greenland, an organic-rich deposit was discovered at an elevation of 480 m above sea level. The sediments contained remains of vascular plants, mosses, beetles, caddisflies, midges, bryozoans, sponges and other invertebrates. The fossils were deposited in a boreal environment with a mean July air temperature that was at least 9 °C higher than at present.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"52 1","pages":"27-41"},"PeriodicalIF":2.2,"publicationDate":"2022-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.12596","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42292564","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":"Stratigraphic and geotechnical characterization of regionally extensive and highly competent shallow sand units in the southern North Sea","authors":"Matthias Fleischer,&nbsp;Ayobami Abegunrin,&nbsp;Daniel A. Hepp,&nbsp;Stefan Kreiter,&nbsp;Mark Coughlan,&nbsp;Tobias Mörz","doi":"10.1111/bor.12595","DOIUrl":"10.1111/bor.12595","url":null,"abstract":"<p>A detailed stratigraphic and geotechnical investigation of the uppermost 50 m below the sea floor was carried out for parts of the German North Sea sector using combined information from shallow seismic reflection surveys, 50-m-long sediment cores and cone penetration tests covering an area of ~150 km². While most recent studies concentrate on unusual features such as buried tunnel- or river-valleys, this study focused on the less well understood, regionally dominant sand units deposited after the retreat of the last glaciers in this region. We identified two sandy units which dominate the late- to post-Saalian geology: (i) the Upper Fluvial Member, believed to be derived from deposition of the Weser, Ems and Elbe palaeorivers as well as other tributaries of the Elbe Palaeovalley in the NE during the Saalian; and (ii) the Aeolian Member, which correlates with periglacial deposits of Weichselian age. Additionally, a Saalian Buried Valley Member believed to comprise fluvial deposit was also identified. Key stratigraphic units within the uppermost 50 m below the sea floor were also identified and mapped. Detailed geotechnical properties were obtained for each of the individual stratigraphic units. The regional extent of the Aeolian and Upper Fluvial Members was documented in the region west of the Elbe Palaeovalley and south of the Dogger Bank, where their geotechnical properties are important for foundation design. In conclusion, the study complements the established regional geotechno-stratigraphy and offers new and detailed publically accessible information beneficial for offshore wind farm development within the region.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"52 1","pages":"78-98"},"PeriodicalIF":2.2,"publicationDate":"2022-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.12595","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49459762","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":"Contributions of climate, vegetation and soil to the alpine sediment carbon accumulation rate in central China since the Middle Holocene","authors":"Ying Cheng,&nbsp;Hongyan Liu,&nbsp;Hongya Wang,&nbsp;Qian Hao,&nbsp;Keqin Duan,&nbsp;Zhibao Dong","doi":"10.1111/bor.12597","DOIUrl":"10.1111/bor.12597","url":null,"abstract":"<p>Large amounts of carbon in alpine sediments have been expected to be sensitive to climate change, but how carbon accumulation responds to climate change remains unclear. Thus, we explored the impact of different factors on the carbon accumulation rate (CAR) of alpine sediments by combining a variety of climatic variables, vegetation data and erosion indicators based on two alpine sediment successions on Taibai Mountain, the highest peak in central and eastern mainland China. One succession is near the modern treeline (Paomaliang Swamp, PML) and the other is located at the upper forest line (Sanqing Chi, SQC, a small lake). We used our previously published organic carbon content data and for the first time calculated the CAR, and further used pollen and physicochemical indicators to quantify the contributions from climate, vegetation and soil. We found that their contributions varied during different periods and between the two sediment successions. For the PML succession, from 5850 to 4000 calendar years before present (cal. a BP), the CAR was low, which was related to low annual temperatures, low vegetation cover and strong soil erosion. From 4000 to 2400 cal. a BP, a high CAR coincided with high annual temperatures, high vegetation cover and weak soil erosion. From 2400 to 200 cal. a BP, the CAR decreased, mainly attributed to low vegetation cover. Local vegetation cover had major impacts on the CAR in the SQC succession during the Middle–Late Holocene. In general, the local factor interpretation rate in SQC (83%) was higher than that of PML (47%), related to the vegetation stability of continuous forest and the treeline. This study highlights the important role of the local environment in determining carbon accumulation in the alpine region.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"52 1","pages":"99-108"},"PeriodicalIF":2.2,"publicationDate":"2022-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.12597","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43441223","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":"Northeast Greenland: ice-free shelf edge at 79.4°N around the Last Glacial Maximum 25.5–17.5 ka","authors":"Tine L. Rasmussen,&nbsp;Christof Pearce,&nbsp;Katrine Juul Andresen,&nbsp;Tove Nielsen,&nbsp;Marit-Solveig Seidenkrantz","doi":"10.1111/bor.12593","DOIUrl":"10.1111/bor.12593","url":null,"abstract":"<p>The size of the last glacial ice sheet on the Northeast (NE) Greenland shelf and its interaction with ocean circulation have been the subject of debate. Here we provide insights into the extent of the ice sheet around the Last Glacial Maximum (LGM) and investigate timing and strength of changes in the flow of Atlantic Water. The study is based on a multiproxy investigation of a marine sediment core, gravity core DA17-NG-ST01-019G, from 323-m water depth at the NE Greenland shelf edge at 79.4°N. We present benthic and planktic foraminiferal distribution data, AMS-¹⁴C dates, sedimentological (ice-rafted debris (IRD) and grain sizes), and geochemical (XRF) data in combination with geophysical (sub-bottom profiler) data. The oldest sediments at the study site are dated to 25.5–17.5 ka, encompassing the time frame from the beginning of the LGM to the early deglaciation. This part is overlain by sediments from the late deglaciation and Holocene. The deposits dating from the LGM are very rich in both planktic and benthic foraminifera and macrofossils of excellent preservation. The faunas show that the site generally was affected by a strong flow of relatively warm subsurface Atlantic Water during the LGM and Early Holocene. Conditions turned more polar with cold bottom water flow in the Middle–Late Holocene (<i>c</i>. 7.5 ka to Recent) with presence of mainly agglutinated benthic foraminiferal species. Our data from the LGM also indicate that the deposits were mixed by iceberg scouring, confirmed by the geophysical data showing extensive ploughing of the sediments on the outer shelf area. The results further indicate that the Greenland Ice Sheet did not reach to the edge of the NE Greenland shelf at 79.4°N during the LGM 24–18 ka.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"51 4","pages":"759-775"},"PeriodicalIF":2.2,"publicationDate":"2022-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.12593","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43466874","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":"High-resolution environmental changes recorded in ostracod and mollusc fauna from the Holsteinian palaeolake at Ortel Królewski II, eastern Poland","authors":"Monika Czajkowska","doi":"10.1111/bor.12588","DOIUrl":"10.1111/bor.12588","url":null,"abstract":"<p>To better understand the environmental variability during the Holsteinian interglacial, fauna of the palaeolake deposits at Ortel Królewski II, eastern Poland was investigated. The analysis covered the uppermost part of the profile, representing the so-called pre-optimal part of the Holsteinian interglacial (MIS 11c), namely the <i>Taxus</i> and <i>Pinus-Larix</i> pollen zones. Variability within the structure and composition of the faunal assemblage enabled a high-resolution palaeoecological reconstruction – lake level and temperature fluctuations, its trophy and energy of the environment. During the <i>Taxus</i> pollen zone the lake was relatively deep and characterized by medium trophy conditions, which is indicated by a low abundance of molluscs of temporary water bodies and low numbers of <i>Metacypris cordata</i> and <i>Scottia tumida</i>. The temperature was rather stable with only small fluctuations during the transition between the <i>Taxus</i> and <i>Pinus-Larix</i> zones. The occurrence of some cold-loving ostracod species within the beginning of the <i>Pinus-Larix</i> pollen zone indicates some deterioration of thermal conditions, which was additionally confirmed by using the mutual ostracod temperature range (MOTR) method. Lake level drop and expansion of reed zones within the <i>Pinus</i>-<i>Larix</i> pollen zone are inferred from the increased abundance of shallow water ostracod and mollusc species as well as from an increased Bithynia-index (BIN). The short cooling event documented early in the <i>Pinus-Larix</i> zone in the studied profile might be an equivalent to the mid-MIS 11c cooling, the so-called Older Holsteinian Oscillation. Thus, the improved knowledge about the climate dynamics recorded within the sediments from this site contributes to a better understanding of the spatial extent and pattern of the climatic changes within the Holsteinian interglacial across Europe.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"51 4","pages":"793-809"},"PeriodicalIF":2.2,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.12588","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48399271","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":"Early taphonomy of benthic foraminifera in Storfjorden ‘sea-ice factory’: the agglutinated/calcareous ratio as a proxy for brine persistence","authors":"Maria Pia Nardelli,&nbsp;Eleonora Fossile,&nbsp;Olivier Péron,&nbsp;Hélène Howa,&nbsp;Meryem Mojtahid","doi":"10.1111/bor.12592","DOIUrl":"10.1111/bor.12592","url":null,"abstract":"<p>The recurrent latent-heat polynya characterizing Storfjorden (Svalbard, Norway) triggers seasonal formation of thin first-year sea ice. This leads to the production of dense, salty, and corrosive brines that cascade towards the sea floor and mix with shelf waters. The bottom topography of the fjord is responsible for the retention of these dense waters in two central deep basins throughout the year. Recent studies show that living benthic foraminifera in Storfjorden are particularly affected by the persistence of brines on the sea floor, with a strong dominance of agglutinated (A) species and high degrees of dissolution of calcareous(C) faunas. Therefore, the A/C ratio, calculated on living faunas, was proposed as a proxy for brine persistence. In the present study we analyse the fossil faunas, found below the taphonomically active zone, to investigate the residual signal of the A/C proxy after the intense early taphonomic processes and challenge its applicability in sedimentary archives. Our results show that despite the generally high taphonomic loss inside the fjord, a high proportion of agglutinated species is still visible in fossil faunas at the stations experiencing regular and/or persistent presence of brine-enriched shelf waters. These results support the application of the A/C ratio in historical records to reconstruct the persistence of brines and indirectly the first-year sea ice formation in Storfjorden. This can be further applied to other Arctic fjords with similar settings and characterized by the production of brines during the winter–early spring season.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"52 1","pages":"109-123"},"PeriodicalIF":2.2,"publicationDate":"2022-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.12592","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48572850","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":"Season-of-death and age-at-death of the easternmost European cave bears: Cementum and dentine increment analysis provides new insight into the cave bear ecology","authors":"Natalya E. Prilepskaya,&nbsp;Olga P. Bachura,&nbsp;Gennady F. Baryshnikov","doi":"10.1111/bor.12590","DOIUrl":"10.1111/bor.12590","url":null,"abstract":"<p>Cementum and dentine increment analysis was used for the first time to study the remains of cave bears from European Russia, the Urals and the Caucasus. This study analysed 12 canines belonging to 12 different individuals (five males and seven females) from genetically different lineages of cave bears. The increment analysis showed that all studied cave bears belong to the categories adults and old animals (from 10 to 32.5 years). The enamel crowns of all 12 canines were broken and/or had wear facets. Seven canines studied were severely broken (more than one-third of a canine crown missing). Significant damage to dental crowns may indicate old age, conflict between males and/or high food abrasion. The absence of significant differences in the extent of canine breakage between the youngest and the oldest animals, as well as between the males and the females, may indicate a significant role of food abrasiveness in the process of the grinding of canines. Until now, the question of whether these animals visited caves year-round or stayed there mainly for overwintering remained open. The increment analysis showed different seasons of the bears’ death. Six individuals died in the warm season and four individuals died in the cold season. In all of the studied caves (excluding Medvezhiya Cave) the animals died in the warm season as well as in the cold season. All of the studied females perished either during the cold season or at the very beginning of the warm season. On the contrary, almost all of the examined males perished in the warm season. Thus, the cave bears visited the caves year-round. This study raises new questions in the study of the ecology of cave bears from different parts of their range.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":"51 4","pages":"810-823"},"PeriodicalIF":2.2,"publicationDate":"2022-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.12590","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49241524","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}