J. Leigh, Richard S. Jones, C. R. Stokes, David J. A. Evans, J. R. Carr, L. Andreassen
Here we present the first Lateglacial and Holocene glacial history from Rotsunddalen, northern Troms and western Finnmark county, northern Norway, based on both relative and numerical moraine dating using Schmidt hammer, soil chronosequencing and terrestrial cosmogenic nuclide dating. We combine these chronological data with a regional map of the glacial geomorphology to hypothesize key events in the glacial history from around 14 ka to present. Our reconstruction shows that, following deglaciation of the main ice sheet across central Troms and Finnmark, mountain glaciers were terminating on land, close to the coast, between around 12.1 and 10.6 ka. Continued recession of the main Fennoscandian Ice Sheet margin towards the SE led to the isolation of several large plateau icefields and outlet glaciers that generated moraines at around 10.2–9.2 ka, which we ascribe to the Erdalen Event, and 8.4–8.2 ka, which is broadly contemporaneous with the 8.2 ka cold event. Although the latter corresponds with the Scandinavian Finse Event, very few moraines have been dated to this time and we therefore view it as a tentative hypothesis for future work to test. During the Holocene Thermal Maximum (~6.6 to 6.3 ka) most (if not all) glaciers in the region disappeared, but then regrew during the Neoglaciation and produced large moraines dated to around 4.7 ka that lie a few hundred metres distal to the prominent Little Ice Age moraines (previously dated to AD 1810s–1870s). Given the limitations of our dating approach, the preservation of moraines dated to this period in northern Norway also warrants further investigation. We also highlight that terrestrial cosmogenic nuclide dating of the moraines is not consistent with other dating approaches and the widely established deglaciation history of the region, probably owing to cosmogenic inheritance and insufficient glacial erosion.
在此，我们首次介绍了挪威北部特罗姆斯岛北部和芬马克郡西部罗森达伦（Rotsunddalen）的大冰期（Lateglacial）和全新世（Holocene）冰川史，其依据是使用施密特锤（Schmidt hammer）进行的相对和数值冰碛测年、土壤年代测序和陆地宇宙成因核素测年。我们将这些年代学数据与冰川地貌区域图相结合，假设了从大约 14 ka 年至今的冰川历史中的关键事件。我们的重建结果表明，在横跨特罗姆斯和芬马克中部的主冰原消融之后，大约在 12.1 ka 到 10.6 ka 之间，山地冰川在靠近海岸的陆地上终止。芬诺斯坎迪亚主冰原边缘向东南方向的持续后退导致了几个大型高原冰原和出口冰川的分离，这些冰川在大约 10.2-9.2 ka（我们将其归于厄尔达伦事件）和 8.4-8.2 ka（与 8.2 ka 寒冷事件大致同时）产生了冰碛。尽管后者与斯堪的纳维亚芬斯事件（Scandinavian Finse Event）相吻合，但很少有冰碛被测定为这一时期，因此我们将其视为一个暂定假设，有待未来工作的检验。在全新世热极盛期（约 6.6 至 6.3 ka），该地区的大部分（如果不是全部）冰川消失，但在新冰期又重新生长，并产生了年代约为 4.7 ka 的大型冰碛，这些冰碛位于著名的小冰期冰碛（以前的年代为公元 1810 年代至 1870 年代）的几百米远处。鉴于我们测年方法的局限性，挪威北部保存的这一时期的冰碛也值得进一步研究。我们还强调，这些冰碛的陆地宇宙成因核素年代测定与其他年代测定方法以及该地区广泛确定的冰川消融历史并不一致，这可能是由于宇宙成因继承和冰川侵蚀不充分造成的。
{"title":"Reconstructing the Holocene glacial history of northern Troms and western Finnmark, Arctic Norway","authors":"J. Leigh, Richard S. Jones, C. R. Stokes, David J. A. Evans, J. R. Carr, L. Andreassen","doi":"10.1111/bor.12668","DOIUrl":"https://doi.org/10.1111/bor.12668","url":null,"abstract":"Here we present the first Lateglacial and Holocene glacial history from Rotsunddalen, northern Troms and western Finnmark county, northern Norway, based on both relative and numerical moraine dating using Schmidt hammer, soil chronosequencing and terrestrial cosmogenic nuclide dating. We combine these chronological data with a regional map of the glacial geomorphology to hypothesize key events in the glacial history from around 14 ka to present. Our reconstruction shows that, following deglaciation of the main ice sheet across central Troms and Finnmark, mountain glaciers were terminating on land, close to the coast, between around 12.1 and 10.6 ka. Continued recession of the main Fennoscandian Ice Sheet margin towards the SE led to the isolation of several large plateau icefields and outlet glaciers that generated moraines at around 10.2–9.2 ka, which we ascribe to the Erdalen Event, and 8.4–8.2 ka, which is broadly contemporaneous with the 8.2 ka cold event. Although the latter corresponds with the Scandinavian Finse Event, very few moraines have been dated to this time and we therefore view it as a tentative hypothesis for future work to test. During the Holocene Thermal Maximum (~6.6 to 6.3 ka) most (if not all) glaciers in the region disappeared, but then regrew during the Neoglaciation and produced large moraines dated to around 4.7 ka that lie a few hundred metres distal to the prominent Little Ice Age moraines (previously dated to AD 1810s–1870s). Given the limitations of our dating approach, the preservation of moraines dated to this period in northern Norway also warrants further investigation. We also highlight that terrestrial cosmogenic nuclide dating of the moraines is not consistent with other dating approaches and the widely established deglaciation history of the region, probably owing to cosmogenic inheritance and insufficient glacial erosion.","PeriodicalId":9184,"journal":{"name":"Boreas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141353004","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}
Glacial deposits are important sources of palaeoclimatic information but not all deposits are formed by processes that reflect the overall climatic conditions of a region; surge‐type glaciers undergo periodic episodes of rapid ice movement, often unrelated to ambient climatic conditions. This study examines the glacier forefields of Öldufellsjökull and western Sléttjökull, two outlet glaciers of the Mýrdalsjökull Ice Cap in southern Iceland, to identify landform characteristics indicative of past episodes of fast flow. Previous studies suggest episodes of fast flow at these glaciers in the past century. Remotely sensed data and field investigations were combined to complete a landsystem analysis of the forefields of these glaciers and an uncrewed aerial vehicle was used to collect high‐resolution imagery of areas of particular interest. Two assemblages of landsystems are identified on each forefield, which pass from streamlined landforms containing abundant flutes close to the glacier to spatially restricted bands of arcuate moraines with associated glaciofluvial and glaciolacustrine deposits more distally. This distribution of landsystem tracts has limited similarity to the current surge‐type glacier landsystem model, suggesting that other processes are controlling the development of landform–sediment assemblages. Using a high‐resolution digital elevation model of an area within the 1984 ice margin, two distinct landform types were identified that were not apparent on the coarse resolution imagery: hummocky moraine and a circular feature hypothesized to have formed as a result of water escape caused by changing hydrological regimes. The forefields of Öldufellsjökull and western Sléttjökull lack many of the characteristics typical of surge‐type landsystems and instead are more similar to the active temperate landsystem common in Iceland.
{"title":"Landsystem analysis of temperate non‐surging glaciers on the Mýrdalsjökull Ice Cap, southern Iceland","authors":"Rebecca E. Lee, R. N. Narro Pérez, C. Eyles","doi":"10.1111/bor.12667","DOIUrl":"https://doi.org/10.1111/bor.12667","url":null,"abstract":"Glacial deposits are important sources of palaeoclimatic information but not all deposits are formed by processes that reflect the overall climatic conditions of a region; surge‐type glaciers undergo periodic episodes of rapid ice movement, often unrelated to ambient climatic conditions. This study examines the glacier forefields of Öldufellsjökull and western Sléttjökull, two outlet glaciers of the Mýrdalsjökull Ice Cap in southern Iceland, to identify landform characteristics indicative of past episodes of fast flow. Previous studies suggest episodes of fast flow at these glaciers in the past century. Remotely sensed data and field investigations were combined to complete a landsystem analysis of the forefields of these glaciers and an uncrewed aerial vehicle was used to collect high‐resolution imagery of areas of particular interest. Two assemblages of landsystems are identified on each forefield, which pass from streamlined landforms containing abundant flutes close to the glacier to spatially restricted bands of arcuate moraines with associated glaciofluvial and glaciolacustrine deposits more distally. This distribution of landsystem tracts has limited similarity to the current surge‐type glacier landsystem model, suggesting that other processes are controlling the development of landform–sediment assemblages. Using a high‐resolution digital elevation model of an area within the 1984 ice margin, two distinct landform types were identified that were not apparent on the coarse resolution imagery: hummocky moraine and a circular feature hypothesized to have formed as a result of water escape caused by changing hydrological regimes. The forefields of Öldufellsjökull and western Sléttjökull lack many of the characteristics typical of surge‐type landsystems and instead are more similar to the active temperate landsystem common in Iceland.","PeriodicalId":9184,"journal":{"name":"Boreas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141353347","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}
T. Saks, Vincent Rinterknecht, Ivan Lavrentiev, Gabriel Béra, Enrico Mattea, M. Hoelzle
The Koksu River valley is located in the Pamir‐Alay mountain range and contains 25 glaciers larger than 1 km2 and numerous smaller glaciers. The largest glacier in the catchment is Abramov Glacier with a current surface area of 22.55 km2 (in 2022), which was extensively monitored between 1965 and 1999, and resumed in 2011. The long and detailed mass balance time series provide, among other information, benchmark climate variables for the Pamir‐Alay range. We report 10 new cosmogenic 10Be exposure dates of glacial moraines directly deposited by Abramov Glacier to extend the glacial history of the valley. Six boulders indicate that the Local Last Glacial Maximum occurred at 17.1±1.0 ka. Four boulders suggest a Little Ice Age (LIA) glacial advance around AD 1750. Secular glacier mass balance reconstructions suggest a progressively negative mass balance since the LIA advance. The decrease in mass balance accelerated in the last quarter of the 20th century. Results from repeated ground penetrating radar (GPR) measurements suggest that Abramov Glacier lost about 403 million m3 of ice volume between 1986 and 2018. Based on the reconstruction of the glacier surface, the corresponding equilibrium line altitude, which is closely correlated with the mass balance, increased by about 70 to 80 m during this period. Our results also suggest that Abramov Glacier has become increasingly out of equilibrium with the climate over the last two decades. This is supported by repeated GPR measurements of the tongue area, which indicate a dramatic decrease in glacier area and ice volume over the period 1986–2018.
{"title":"Acceleration of Abramov Glacier (Pamir‐Alay) retreat since the Little Ice Age","authors":"T. Saks, Vincent Rinterknecht, Ivan Lavrentiev, Gabriel Béra, Enrico Mattea, M. Hoelzle","doi":"10.1111/bor.12659","DOIUrl":"https://doi.org/10.1111/bor.12659","url":null,"abstract":"The Koksu River valley is located in the Pamir‐Alay mountain range and contains 25 glaciers larger than 1 km2 and numerous smaller glaciers. The largest glacier in the catchment is Abramov Glacier with a current surface area of 22.55 km2 (in 2022), which was extensively monitored between 1965 and 1999, and resumed in 2011. The long and detailed mass balance time series provide, among other information, benchmark climate variables for the Pamir‐Alay range. We report 10 new cosmogenic 10Be exposure dates of glacial moraines directly deposited by Abramov Glacier to extend the glacial history of the valley. Six boulders indicate that the Local Last Glacial Maximum occurred at 17.1±1.0 ka. Four boulders suggest a Little Ice Age (LIA) glacial advance around AD 1750. Secular glacier mass balance reconstructions suggest a progressively negative mass balance since the LIA advance. The decrease in mass balance accelerated in the last quarter of the 20th century. Results from repeated ground penetrating radar (GPR) measurements suggest that Abramov Glacier lost about 403 million m3 of ice volume between 1986 and 2018. Based on the reconstruction of the glacier surface, the corresponding equilibrium line altitude, which is closely correlated with the mass balance, increased by about 70 to 80 m during this period. Our results also suggest that Abramov Glacier has become increasingly out of equilibrium with the climate over the last two decades. This is supported by repeated GPR measurements of the tongue area, which indicate a dramatic decrease in glacier area and ice volume over the period 1986–2018.","PeriodicalId":9184,"journal":{"name":"Boreas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140962529","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}
Pierre Antoine, N. Limondin‑Lozouet, J. Dabkowski, J. Bahain, Bassam Ghaleb, J. Reyss, P. Auguste, Noémie Sévêque, Guillaume Jamet, Marie-Claude Jolly-Saad, Agnès Gauthier, Loïc Lebreton, J. Locht
The calcareous tufa sequence and associated Palaeolithic site of Caours were discovered in 2002 during a test‐pit campaign aimed at identifying last interglacial (MIS 5e) archives in the fluvial terrace system of the Somme basin, northern France. The presence of an outstanding stratigraphical succession with four in situ Palaeolithic layers within the tufa sequence has motivated archaeological excavations of the site since 2005. The first malacological studies and U‐series ages quickly showed that the sequence was mainly deposited during the Eemian interglacial (MIS 5e). After 20 years of investigations, we propose here a summary of this multidisciplinary research project including stratigraphy, sedimentology, geochronology, geochemistry, malacology, mammals, palaeovegetation and archaeology. By combining 25 dates obtained by U‐series, ESR/U‐series, TL and OSL methods, the Caours calcareous tufa sequence is securely dated to the Eemian (123.1±2.8 ka). Based on the summary of the whole information, we propose a robust and detailed reconstruction of the modification of the valley environments between the Late Saalian and the Early Weichselian. At the scale of northwestern Europe, Caours provides a reference terrestrial molluscs record for the Eemian interglacial, including the climatic optimum, that is also described in the same layers by δ18O and δ13C analyses on calcite and by mammal remains. Moreover, the 300‐m‐long transect crossing the fluvial terrace covered by the tufa sequence and the bottom valley formation, combined with the chronology established from U‐series and OSL ages, shows that the incision of the present‐day valley, leading to the setting of the Very Low Terrace, was achieved during the first stages of the Early Weichselian (MIS 5d–5c). From an archaeological point of view, the configuration of the Caours site is unique at the scale of western Europe and demonstrates the adaptation of Neandertals to a forested environment and to fully temperate conditions during the Eemian.
{"title":"Last interglacial in western Europe: 20 years of multidisciplinary research on the Eemian (MIS 5e) calcareous tufa sequence at Caours (Somme basin, France) – a review","authors":"Pierre Antoine, N. Limondin‑Lozouet, J. Dabkowski, J. Bahain, Bassam Ghaleb, J. Reyss, P. Auguste, Noémie Sévêque, Guillaume Jamet, Marie-Claude Jolly-Saad, Agnès Gauthier, Loïc Lebreton, J. Locht","doi":"10.1111/bor.12654","DOIUrl":"https://doi.org/10.1111/bor.12654","url":null,"abstract":"The calcareous tufa sequence and associated Palaeolithic site of Caours were discovered in 2002 during a test‐pit campaign aimed at identifying last interglacial (MIS 5e) archives in the fluvial terrace system of the Somme basin, northern France. The presence of an outstanding stratigraphical succession with four in situ Palaeolithic layers within the tufa sequence has motivated archaeological excavations of the site since 2005. The first malacological studies and U‐series ages quickly showed that the sequence was mainly deposited during the Eemian interglacial (MIS 5e). After 20 years of investigations, we propose here a summary of this multidisciplinary research project including stratigraphy, sedimentology, geochronology, geochemistry, malacology, mammals, palaeovegetation and archaeology. By combining 25 dates obtained by U‐series, ESR/U‐series, TL and OSL methods, the Caours calcareous tufa sequence is securely dated to the Eemian (123.1±2.8 ka). Based on the summary of the whole information, we propose a robust and detailed reconstruction of the modification of the valley environments between the Late Saalian and the Early Weichselian. At the scale of northwestern Europe, Caours provides a reference terrestrial molluscs record for the Eemian interglacial, including the climatic optimum, that is also described in the same layers by δ18O and δ13C analyses on calcite and by mammal remains. Moreover, the 300‐m‐long transect crossing the fluvial terrace covered by the tufa sequence and the bottom valley formation, combined with the chronology established from U‐series and OSL ages, shows that the incision of the present‐day valley, leading to the setting of the Very Low Terrace, was achieved during the first stages of the Early Weichselian (MIS 5d–5c). From an archaeological point of view, the configuration of the Caours site is unique at the scale of western Europe and demonstrates the adaptation of Neandertals to a forested environment and to fully temperate conditions during the Eemian.","PeriodicalId":9184,"journal":{"name":"Boreas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140652844","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}
I. Candy, Dulce Oliveira, Daniel Parkes, Jennifer Sherriff, David Thornalley
The interglacial known as MIS 11c (c. 426 000–396 000 years ago) receives intensive international interest because of its perceived role as an analogue for the current interglacial and its importance for understanding future climate change. Here we review the current understanding of the stratigraphy of this interglacial in Europe. This study considers (i) the evidence for the environmental history of this interglacial as reconstructed from the varved lake records from northern Europe, (ii) the climate history of MIS 11c as preserved in the long pollen records of southern Europe and (iii) a comparison of both of these with marine records from the North Atlantic. The result of this review is a discussion of the evidence for millennial and centennial scale climate change found in European records of MIS 11c, the patterns of warming that are seen across this interglacial and the discrepancy in aspects of the duration of this interglacial that seems to exist between the marine and terrestrial records of this warm period. A review of the recent advances in the study of MIS 11c in Europe confirms its importance for understanding both the past evolution of the Holocene and the future patterns of long‐term climate change.
被称为 MIS 11c（约 426 000-396 000 年前）的间冰期受到了国际社会的广泛关注，因为它被认为是当前间冰期的类似物，对了解未来气候变化具有重要意义。在此，我们回顾了目前对欧洲此次间冰期地层学的理解。本研究考虑了（i）从北欧的变湖泊记录中重建的本次间冰期环境历史的证据，（ii）南欧长花粉记录中保存的 MIS 11c 的气候历史，以及（iii）这两个方面与北大西洋海洋记录的比较。这项研究的成果是对欧洲 MIS 11c 记录中发现的千年和百年尺度气候变化的证据、整个间冰期的变暖模式以及这一温暖时期的海洋和陆地记录在间冰期持续时间方面似乎存在的差异进行了讨论。对欧洲 MIS 11c 研究最新进展的回顾证实了它对了解全新世过去的演变和未来长期气候变化模式的重要性。
{"title":"Marine Isotope Stage 11c in Europe: Recent advances in marine–terrestrial correlations and their implications for interglacial stratigraphy – a review","authors":"I. Candy, Dulce Oliveira, Daniel Parkes, Jennifer Sherriff, David Thornalley","doi":"10.1111/bor.12656","DOIUrl":"https://doi.org/10.1111/bor.12656","url":null,"abstract":"The interglacial known as MIS 11c (c. 426 000–396 000 years ago) receives intensive international interest because of its perceived role as an analogue for the current interglacial and its importance for understanding future climate change. Here we review the current understanding of the stratigraphy of this interglacial in Europe. This study considers (i) the evidence for the environmental history of this interglacial as reconstructed from the varved lake records from northern Europe, (ii) the climate history of MIS 11c as preserved in the long pollen records of southern Europe and (iii) a comparison of both of these with marine records from the North Atlantic. The result of this review is a discussion of the evidence for millennial and centennial scale climate change found in European records of MIS 11c, the patterns of warming that are seen across this interglacial and the discrepancy in aspects of the duration of this interglacial that seems to exist between the marine and terrestrial records of this warm period. A review of the recent advances in the study of MIS 11c in Europe confirms its importance for understanding both the past evolution of the Holocene and the future patterns of long‐term climate change.","PeriodicalId":9184,"journal":{"name":"Boreas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140690937","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}
Andrei A. Andreev, P. Tarasov, M. Lenz, M. M. Lenz, S. Scheidt, G. Fedorov, Bernd Wagner, M. Melles
Environmental changes on the northern Taymyr Peninsula were reconstructed based on a new pollen record from a 46‐m‐long sediment core recovered from Lake Levinson‐Lessing (latitude 74°27′54″N, longitude 98°39′58″E). The record is continuous and has a relatively good age control and high temporal resolution. Reaching a basal age of 62 cal. ka BP, it provides a unique environmental archive for the central Russian Arctic. The results reveal that open landscapes dominated 62.0–50.8 cal. ka BP, but presence of shrubs reflects a relatively warm summer climate. Numerous Pediastrum colonies in the sediments point to a rather low lake stand. A decrease in algae remains in the pollen spectra reflects a higher lake level after c. 50.8 cal. ka BP. From c. 47.8 to 25.5 cal. ka BP, lower contents of Betula and higher percentages of herb pollen point to colder and drier conditions. Besides, larger amounts of Pre‐Quaternary palynomorphs and Pediastrum colonies point to increased erosion processes and a lower lake stand. After c. 25.5 cal. ka BP, herb communities further increased. Poaceae and Artemisia show the highest contents between c. 20.3 and 19.2 cal. ka BP, suggesting the coldest and driest climatic conditions during the studied time interval coincident with the Last Glacial Maximum (LGM). Pollen spectra dated c. 19.20–16.05 cal. ka BP reflect a slightly warmer and wetter climate in comparison to the LGM. Increased amounts of coprophilous fungi spores indirectly indicate that grazing animals were abundant around the lake. After с. 16.05 cal. ka BP, increases in shrubs and sedges reflect somewhat warmer and/or wetter conditions. The pollen data also well document the Allerød warming and Younger Dryas cooling events, reflecting an Atlantic influence on the regional climate development during these times. The transition from the Lateglacial to the Holocene at c. 11.63 cal. ka BP is characterized by drastic increases in pollen of shrubs, which document a significant warming. The Early Holocene (c. 11.63–8.30 cal. ka BP) pollen spectra reflect the Holocene Thermal Maximum in the study region. After c. 8.3 cal. ka BP, gradual cooling prevailed and led to climate conditions similar to modern ones at c. 2 cal. ka BP.
根据从莱文森-莱辛湖（北纬 74°27′54″，东经 98°39′58″）采集的 46 米长沉积岩芯中的新花粉记录，重建了泰米尔半岛北部的环境变化。该记录是连续的，具有较好的年龄控制和较高的时间分辨率。它的基底年龄为公元前 62 千卡，为俄罗斯北极地区中部提供了一个独特的环境档案。研究结果表明，在公元前 62.0-50.8 年，开阔地占主导地位，但灌木的存在反映了相对温暖的夏季气候。沉积物中大量的Pediastrum菌落表明湖泊面积相当小。花粉光谱中藻类残骸的减少反映了约公元前 50.8 千年后湖泊水位的升高。在约公元前 47.8 至 25.5 千年前，桦树花粉含量较低，而草本花粉所占比例较高，这表明当时的环境更加寒冷和干燥。此外，较多的前第四纪古生物和Pediastrum菌落表明侵蚀过程加剧，湖泊面积减少。约 25.5 cal. ka BP 之后，草本群落进一步增加。草本植物和蒿属植物在约公元前 20.3 至 19.2 年间含量最高，表明在研究时间段内气候条件最寒冷、最干旱，与末次冰川极盛时期（LGM）相吻合。年代约为 19.20-16.05 cal. ka BP 的花粉谱反映了与末次冰川大期相比略微温暖湿润的气候。共亲真菌孢子数量的增加间接表明湖泊周围有大量的放牧动物。在 с.16.05 cal. ka BP之后，灌木和莎草的增加反映出当时的气候更加温暖和/或潮湿。花粉数据还很好地记录了阿勒罗德气候变暖和幼年旱季气候变冷的事件，反映了大西洋在这些时期对区域气候发展的影响。在约 11.63 cal. ka BP 时，从大冰期向全新世过渡，灌木花粉急剧增加，记录了显著的变暖。全新世早期（约 11.63-8.30 cal. ka BP）的花粉图谱反映了研究地区全新世热量最高时期的情况。约 8.3 cal. ka BP 之后，气候逐渐变冷，导致气候条件与约 2 cal. ka BP 时的现代气候条件相似。
{"title":"Environmental changes on the northern Taymyr Peninsula (Russian Arctic) during the last 62 ka inferred from the lacustrine pollen record","authors":"Andrei A. Andreev, P. Tarasov, M. Lenz, M. M. Lenz, S. Scheidt, G. Fedorov, Bernd Wagner, M. Melles","doi":"10.1111/bor.12657","DOIUrl":"https://doi.org/10.1111/bor.12657","url":null,"abstract":"Environmental changes on the northern Taymyr Peninsula were reconstructed based on a new pollen record from a 46‐m‐long sediment core recovered from Lake Levinson‐Lessing (latitude 74°27′54″N, longitude 98°39′58″E). The record is continuous and has a relatively good age control and high temporal resolution. Reaching a basal age of 62 cal. ka BP, it provides a unique environmental archive for the central Russian Arctic. The results reveal that open landscapes dominated 62.0–50.8 cal. ka BP, but presence of shrubs reflects a relatively warm summer climate. Numerous Pediastrum colonies in the sediments point to a rather low lake stand. A decrease in algae remains in the pollen spectra reflects a higher lake level after c. 50.8 cal. ka BP. From c. 47.8 to 25.5 cal. ka BP, lower contents of Betula and higher percentages of herb pollen point to colder and drier conditions. Besides, larger amounts of Pre‐Quaternary palynomorphs and Pediastrum colonies point to increased erosion processes and a lower lake stand. After c. 25.5 cal. ka BP, herb communities further increased. Poaceae and Artemisia show the highest contents between c. 20.3 and 19.2 cal. ka BP, suggesting the coldest and driest climatic conditions during the studied time interval coincident with the Last Glacial Maximum (LGM). Pollen spectra dated c. 19.20–16.05 cal. ka BP reflect a slightly warmer and wetter climate in comparison to the LGM. Increased amounts of coprophilous fungi spores indirectly indicate that grazing animals were abundant around the lake. After с. 16.05 cal. ka BP, increases in shrubs and sedges reflect somewhat warmer and/or wetter conditions. The pollen data also well document the Allerød warming and Younger Dryas cooling events, reflecting an Atlantic influence on the regional climate development during these times. The transition from the Lateglacial to the Holocene at c. 11.63 cal. ka BP is characterized by drastic increases in pollen of shrubs, which document a significant warming. The Early Holocene (c. 11.63–8.30 cal. ka BP) pollen spectra reflect the Holocene Thermal Maximum in the study region. After c. 8.3 cal. ka BP, gradual cooling prevailed and led to climate conditions similar to modern ones at c. 2 cal. ka BP.","PeriodicalId":9184,"journal":{"name":"Boreas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140693812","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}
Sonja Rigterink, Kim J. Krahn, B. Kotrys, Brigitte Urban, Oliver Heiri, Falko Turner, Andre Pannes, A. Schwalb
We present the first climatic and environmental reconstruction based on subfossil chironomid head capsules from the Middle Pleistocene Reinsdorf sequence, Schöningen, northern Germany, corresponding to Marine Isotope Stage 9e‐a. The sequence is characterized by interglacial forest successions followed by alternating woodland and steppe phases. Higher levels of runoff formed lacustrine habitats during post‐interglacial, cool steppe (woodland) phases. These were characterized by diverse chironomid assemblages with up to 27 chironomid morphotypes occurring simultaneously. Warmer forest phases were mostly void of chironomids when the site Schöningen 13 II fell dry owing to higher vegetational coverage and therefore lower runoff. Transitional periods between woodland and steppe phases show higher abundances of profundal, bottom‐dwelling chironomid taxa, suggesting oligo‐mesotrophic aquatic conditions, while steppe phases are dominated by shallow‐lake taxa with higher tolerance to increasing productivity. We applied temperature inference models to the chironomid assemblages based on a Swiss–Norwegian and a Swiss–Norwegian–Polish chironomid–temperature calibration data set to reconstruct mean July air temperatures for the Reinsdorf sequence. The Swiss–Norwegian–Polish training set (TS) seems better suited owing to a longer temperature gradient and the presence of the dominant taxon, Propsilocerus lacustris‐type, which is missing from the Swiss–Norwegian TS. In sections of the record with low taxon richness (Shannon index <2) and a dominance of P. lacustris‐type, indicating increased nutrient impact, summer temperatures may have been overestimated by the Swiss–Norwegian–Polish TS. In the other sections, the chironomid‐based reconstructions based on the Swiss–Norwegian–Polish TS were in line with ostracod and plant remains‐based temperature reconstructions, suggesting summer temperatures of the post‐interglacial Reinsdorf oscillations between 16.5 and 22 °C. Our results show that summer air temperatures were lower during warmer, wetter transitional zones (−0.5–0.2 °C colder/warmer than today) and increasing during cooler, dry steppe phases (1 °C warmer than today), most likely caused by higher continentality.
{"title":"Summer temperatures from the Middle Pleistocene site Schöningen 13 II, northern Germany, determined from subfossil chironomid assemblages","authors":"Sonja Rigterink, Kim J. Krahn, B. Kotrys, Brigitte Urban, Oliver Heiri, Falko Turner, Andre Pannes, A. Schwalb","doi":"10.1111/bor.12658","DOIUrl":"https://doi.org/10.1111/bor.12658","url":null,"abstract":"We present the first climatic and environmental reconstruction based on subfossil chironomid head capsules from the Middle Pleistocene Reinsdorf sequence, Schöningen, northern Germany, corresponding to Marine Isotope Stage 9e‐a. The sequence is characterized by interglacial forest successions followed by alternating woodland and steppe phases. Higher levels of runoff formed lacustrine habitats during post‐interglacial, cool steppe (woodland) phases. These were characterized by diverse chironomid assemblages with up to 27 chironomid morphotypes occurring simultaneously. Warmer forest phases were mostly void of chironomids when the site Schöningen 13 II fell dry owing to higher vegetational coverage and therefore lower runoff. Transitional periods between woodland and steppe phases show higher abundances of profundal, bottom‐dwelling chironomid taxa, suggesting oligo‐mesotrophic aquatic conditions, while steppe phases are dominated by shallow‐lake taxa with higher tolerance to increasing productivity. We applied temperature inference models to the chironomid assemblages based on a Swiss–Norwegian and a Swiss–Norwegian–Polish chironomid–temperature calibration data set to reconstruct mean July air temperatures for the Reinsdorf sequence. The Swiss–Norwegian–Polish training set (TS) seems better suited owing to a longer temperature gradient and the presence of the dominant taxon, Propsilocerus lacustris‐type, which is missing from the Swiss–Norwegian TS. In sections of the record with low taxon richness (Shannon index <2) and a dominance of P. lacustris‐type, indicating increased nutrient impact, summer temperatures may have been overestimated by the Swiss–Norwegian–Polish TS. In the other sections, the chironomid‐based reconstructions based on the Swiss–Norwegian–Polish TS were in line with ostracod and plant remains‐based temperature reconstructions, suggesting summer temperatures of the post‐interglacial Reinsdorf oscillations between 16.5 and 22 °C. Our results show that summer air temperatures were lower during warmer, wetter transitional zones (−0.5–0.2 °C colder/warmer than today) and increasing during cooler, dry steppe phases (1 °C warmer than today), most likely caused by higher continentality.","PeriodicalId":9184,"journal":{"name":"Boreas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140700111","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}
Varvara Bakumenko, A. Poska, M. Płóciennik, Neringa Gastevičienė, B. Kotrys, Tomi P. Luoto, Simon Belle, S. Veski
Here we present a new eastern Baltic Chironomidae training set (TS) containing 35 sites that was collected and merged with neighbouring published Finnish (82 lakes) and northern part of the Polish (nine lakes) TSs. Chironomidae, non‐biting midges, are known to be strongly responsive to the July air temperature and are widely used to infer palaeotemperature. Several modern analogue‐based TSs necessary for calibrating the relationships between mean July air temperature (MJAT) and chironomids are available for Europe. However, none of these is representative of the transitional climate typical for eastern Baltic (Estonia, Latvia, Lithuania). The Finno–Baltic–Polish TS contains 121 sites and covers a geographically continuous 70–50°N latitudinal and 7 °C (12.1–19.2 °C) MJAT gradient. Canonical correspondence analysis revealed that, among the tested environmental variables (pH, water depth, dissolved oxygen, MJAT), the MJAT explains the highest amount of variation, both for the eastern Baltic separately and the Finno–Baltic–Polish TSs. The weighted averaging–partial least squares‐based cross‐validation test reveals that the Finno–Baltic–Polish TS has a low root mean square error of prediction (0.7 °C) confirming the high reliability of the TS. The temperature optima of the taxa included in the new Finno–Baltic–Polish TS and widely used Swiss–Norwegian TS were examined. The observed dissimilarities can be attributed to the differences in the temperature ranges represented by the TS, the taxonomic identification level, the general cosmopolitan taxa distribution patterns and the influence of TS‐specific geographic position, climatic or environmental conditions. The new Finno–Baltic–Polish TS adds to the knowledge on the modern distribution of Chironomidae taxa and widens the geographical area of reliable Chironomid‐based MJAT reconstructions into the eastern European lowland.
{"title":"Chironomidae‐based inference model for mean July air temperature reconstructions in the eastern Baltic area","authors":"Varvara Bakumenko, A. Poska, M. Płóciennik, Neringa Gastevičienė, B. Kotrys, Tomi P. Luoto, Simon Belle, S. Veski","doi":"10.1111/bor.12655","DOIUrl":"https://doi.org/10.1111/bor.12655","url":null,"abstract":"Here we present a new eastern Baltic Chironomidae training set (TS) containing 35 sites that was collected and merged with neighbouring published Finnish (82 lakes) and northern part of the Polish (nine lakes) TSs. Chironomidae, non‐biting midges, are known to be strongly responsive to the July air temperature and are widely used to infer palaeotemperature. Several modern analogue‐based TSs necessary for calibrating the relationships between mean July air temperature (MJAT) and chironomids are available for Europe. However, none of these is representative of the transitional climate typical for eastern Baltic (Estonia, Latvia, Lithuania). The Finno–Baltic–Polish TS contains 121 sites and covers a geographically continuous 70–50°N latitudinal and 7 °C (12.1–19.2 °C) MJAT gradient. Canonical correspondence analysis revealed that, among the tested environmental variables (pH, water depth, dissolved oxygen, MJAT), the MJAT explains the highest amount of variation, both for the eastern Baltic separately and the Finno–Baltic–Polish TSs. The weighted averaging–partial least squares‐based cross‐validation test reveals that the Finno–Baltic–Polish TS has a low root mean square error of prediction (0.7 °C) confirming the high reliability of the TS. The temperature optima of the taxa included in the new Finno–Baltic–Polish TS and widely used Swiss–Norwegian TS were examined. The observed dissimilarities can be attributed to the differences in the temperature ranges represented by the TS, the taxonomic identification level, the general cosmopolitan taxa distribution patterns and the influence of TS‐specific geographic position, climatic or environmental conditions. The new Finno–Baltic–Polish TS adds to the knowledge on the modern distribution of Chironomidae taxa and widens the geographical area of reliable Chironomid‐based MJAT reconstructions into the eastern European lowland.","PeriodicalId":9184,"journal":{"name":"Boreas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140387608","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}
The results of geomorphological mapping and survey of Lateglacial and Holocene displaced shorelines in the Clyde estuary and around Loch Lomond, western central Scotland are described. On the basis of morphology, sedimentology, altitude and radiocarbon dating, four discrete shorelines are identified and are correlated with previously identified Scottish displaced shorelines. The shoreline formerly referred to as the Main Postglacial Shoreline is renamed the Menteith Shoreline. This body of data, combined with data on displaced shorelines for Scotland as a whole has been analysed using Gaussian quadratic trend surface analysis in order to determine the centre of glacio-isostatic displacement for each shoreline. These Gaussian models of palaeo-relative sea-level suggest that the zone of greatest displacement lay NNW of Loch Lomond in the Lateglacial then moved SSE to the region of Loch Lomond during the Holocene and the Clyde in the Late Holocene. The factors responsible for the movement of the zone of greatest uplift are discussed, including temporal variations in the ice-sheet thickness, variations in water load in the adjacent sea-lochs and neotectonic processes. Comparison is made with glacial isostatic adjustment (GIA) models. A sensitivity analysis has been carried out on the use of Gaussian trend surface analysis glacio-isostatic modelling and this is included in the research evaluation, and reported in full in the Supporting Information files, along with the raw data used throughout this study.
{"title":"Patterns of glacio-isostatic adjustment in mainland Scotland: new data from western central Scotland, proximal to the zone of maximum rebound","authors":"David E. Smith, Callum R. Firth, James Rose","doi":"10.1111/bor.12650","DOIUrl":"https://doi.org/10.1111/bor.12650","url":null,"abstract":"<p>The results of geomorphological mapping and survey of Lateglacial and Holocene displaced shorelines in the Clyde estuary and around Loch Lomond, western central Scotland are described. On the basis of morphology, sedimentology, altitude and radiocarbon dating, four discrete shorelines are identified and are correlated with previously identified Scottish displaced shorelines. The shoreline formerly referred to as the Main Postglacial Shoreline is renamed the Menteith Shoreline. This body of data, combined with data on displaced shorelines for Scotland as a whole has been analysed using Gaussian quadratic trend surface analysis in order to determine the centre of glacio-isostatic displacement for each shoreline. These Gaussian models of palaeo-relative sea-level suggest that the zone of greatest displacement lay NNW of Loch Lomond in the Lateglacial then moved SSE to the region of Loch Lomond during the Holocene and the Clyde in the Late Holocene. The factors responsible for the movement of the zone of greatest uplift are discussed, including temporal variations in the ice-sheet thickness, variations in water load in the adjacent sea-lochs and neotectonic processes. Comparison is made with glacial isostatic adjustment (GIA) models. A sensitivity analysis has been carried out on the use of Gaussian trend surface analysis glacio-isostatic modelling and this is included in the research evaluation, and reported in full in the Supporting Information files, along with the raw data used throughout this study.</p>","PeriodicalId":9184,"journal":{"name":"Boreas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/bor.12650","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140351705","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}
Emma Ownsworth, Matthias Moros, Jeremy M. Lloyd, O. Bennike, J. Jensen, T. Blanz, David Selby
This study uses a multiproxy approach including the first use of 187Os/188Os, %C37:4 biomarkers, carbonate content, sedimentological grain size, geochemical X‐ray fluorescence and microfossil benthic foraminifera species combined with radiocarbon dating, measured on six cores from across the Skagerrak, in order to study the Lateglacial to Middle Holocene history of the area. A new chronostratigraphic framework is developed based on the appearance of specific benthic foraminifera species along with changes in carbonate/X‐ray fluorescence and grain size data. This allowed the correlation of cores based on a series of radiocarbon dated tie points. Analysing the cores together reveals several events recorded in the Skagerrak including: (i) an increased freshwater input (bracketed between 13.3 and 11.3 cal. ka BP) signified by radiogenic 187Os/188Os values, high %C37:4 values and an increase in sand content; (ii) the Glomma drainage event, signified by a sudden appearance of Valvulineria as well as higher %C37:4; and (iii) the opening of the Danish Straits and English Channel leading to the development of modern‐day conditions and circulation patterns in the Skagerrak, signified by the appearance of Hyalinea balthica and a fall in %C37:4.
{"title":"Multi‐proxy palaeoenvironmental reconstruction of the Skagerrak from the Lateglacial to Middle Holocene","authors":"Emma Ownsworth, Matthias Moros, Jeremy M. Lloyd, O. Bennike, J. Jensen, T. Blanz, David Selby","doi":"10.1111/bor.12652","DOIUrl":"https://doi.org/10.1111/bor.12652","url":null,"abstract":"This study uses a multiproxy approach including the first use of 187Os/188Os, %C37:4 biomarkers, carbonate content, sedimentological grain size, geochemical X‐ray fluorescence and microfossil benthic foraminifera species combined with radiocarbon dating, measured on six cores from across the Skagerrak, in order to study the Lateglacial to Middle Holocene history of the area. A new chronostratigraphic framework is developed based on the appearance of specific benthic foraminifera species along with changes in carbonate/X‐ray fluorescence and grain size data. This allowed the correlation of cores based on a series of radiocarbon dated tie points. Analysing the cores together reveals several events recorded in the Skagerrak including: (i) an increased freshwater input (bracketed between 13.3 and 11.3 cal. ka BP) signified by radiogenic 187Os/188Os values, high %C37:4 values and an increase in sand content; (ii) the Glomma drainage event, signified by a sudden appearance of Valvulineria as well as higher %C37:4; and (iii) the opening of the Danish Straits and English Channel leading to the development of modern‐day conditions and circulation patterns in the Skagerrak, signified by the appearance of Hyalinea balthica and a fall in %C37:4.","PeriodicalId":9184,"journal":{"name":"Boreas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139840181","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}
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