Download or read book Lacustrine Records of Holocene Climate History and Human driven Landscape Evolution in the Lofoten Islands Norway written by Genevieve Pugsley and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Lake sediments are useful paleoenvironmental archives; however their sensitivity to change depends on lake and catchment-specific characteristics. Here I present analyses of lacustrine records from two contrasting lakes on Vestvågøy in the Lofoten Islands, Norway to investigate regional responses to Holocene climate changes and human-driven landscape evolution. Sediment cores spanning the last c. 7 kyr were collected from Lauvdalsvatnet, a small lake (~0.17 km2) with a steep-sided catchment and large catchment-to-lake-area ratio (~18.8), and Ostadvatnet, a larger lake (~1.2 km2) with a smaller catchment-to-lake-area ratio (~5.2) and lower slope catchment. Sediment analyses included magnetic susceptibility, organic-matter content, bulk density, biogenic silica, CNS elemental analysis, x-radiography and scanning X-ray fluorescence. Chronologies are based on radiocarbon dating of terrestrial macrofossils. In the Lauvdalsvatnet record, which is finely laminated and displays high-frequency variability in all sediment properties throughout, clastic sedimentation indicators increase c. 5.5 ka, and decline c. 2.8 ka. Biogenic silica values abruptly decline c. 3.8 ka. During the late Holocene, a large peak then abrupt, lasting decline in organic-matter content occurs c. 1.9 ka, followed by fluctuations in magnetic susceptibility and increased sedimentation rates starting c. 0.5 ka. In the Ostadvatnet record, C/N values are heightened from c. 3.8-2.8 ka, synchronous with peaks in detrital sedimentation indicators in Lauvdalsvatnet. In the late Holocene portion of the Ostadvatnet record, high-amplitude fluctuations in organic-matter concentration begin c. 2.5 ka, followed by decreasing C/N values and increasing magnetic susceptibility since c. 1.9 ka. I attribute changes in Lauvdalsvatnet sediment characteristics during the mid to late Holocene to changes in precipitation and weathering patterns c. 5.5 and 2.8 ka, and decreasing temperatures beginning c. 3.7 ka associated with regional termination of the Holocene Thermal Maximum. Ostadvatnet was less sensitive to mid-Holocene climate changes, likely due its lower catchment-to-lake-area ratio and the lower slope of its catchment. Both lakes record changes in sediment properties after c. 2.5 ka, which are likely related to the onset of local agriculture and early human population expansion. These results have implications for understanding when and how climate in the Lofoten region responded to past global changes, including during the Holocene thermal maximum and neoglacial transition. They also suggest that onset of agriculture in the central corridor of Vestvågøy c. 2.5 ka preceded settlement in at least one peripheral valley, improving understanding of early human-landscape interactions.

Download or read book Lacustrine Records of Holocene Climate and Environmental Change from the Lofoten Islands Norway written by Nicholas L. Balascio and published by . This book was released on 2011 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lakes sediments from the Lofoten Islands, Norway, can be used to generate well resolved records of past climate and environmental change. This dissertation presents three lacustrine paleoenvironmental reconstructions that show evidence for Holocene climate changes associated with North Atlantic climate dynamics and relative sea-level variations driven by glacio-isostatic adjustment. This study also uses distal tephra deposits (cryptotephra) from Icelandic volcanic eruptions to improve the chronologies of these reconstructions and explores new approaches to crypto-tephrochronology. Past and present conditions at Vikjordvatnet, Fiskebølvatnet, and Heimerdalsvatnet were studied during four field seasons conducted from 2007-2010. Initially, each lake was characterized by measuring water column chemistry, logging annual temperature fluctuations, and conducting bathymetric and seismic surveys. Sediment cores were then collected and analyzed using multiple techniques, including: sediment density, magnetic susceptibility, loss-on-ignition, total carbon and nitrogen, ǒ13 C and ǒ 15 N of organic matter, and elemental compositions acquired by scanning X-ray fluorescence. Chronologies were established using radiocarbon dating and tephrochronology. A 13.8 cal ka BP record from Vikjordvatnet provides evidence for glacial activity during the Younger Dryas cold interval and exhibits trends in Ti, Fe, and organic content during the Holocene that correlate with regional millennial-scale climate trends and provide evidence for more rapid events. A 9.7 cal ka BP record from Fiskebølvatnet shows a strong signal of sediment inwashing likely driven by local geomorphic conditions, although there is evidence that increased inwashing at the onset of the Neoglacial could have been associated with increased precipitation. Heimerdalsvatnet provides a record of relative sea-level change. A 7.8 cal ka BP sedimentary record reflects changes in salinity and water column conditions as the lake was isolated and defines sea-level regression following the Tapes transgression. Cryptotephra horizons were identified in sediments of Heimerdalsvatnet, Vikjordvatnet, and Sverigedalsvatn. They were also found in a Viking-age boathouse excavated along the shore of Inner Borgpollen. These include the GA4-85, BIP-24a, SILK-N2, Askja, 860 Layer B, Hekla 1158, Hekla 1104, Vedde Ash, and Saksunarvatn tephra. This research project also explored the use of scanning XRF to locate cryptotephra in lacustrine sediments and presents experimental results of XRF scans of tephra-spiked synthetic sediment cores.

Download or read book Holocene Climate and Environmental Changes written by Robert M. D'Anjou and published by . This book was released on 2012 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a multi-proxy paleoenvironmental reconstruction from the sedimentary archives of Lilandsvatnet, a small arctic lake on Vestvaêgøy, in the Lofoten Islands, Norway. Lofoten has a rich history of human settlements existing throughout the Holocene. The catchment of Lilandsvatnet was the location of a prominent Viking chieftain farm that existed throughout the Iron Age, and the sedimentary archive contains a strong signal of prehistoric and historic human settlements and land-use practices. Paleoenvironmental reconstructions in this thesis show evidence for Holocene environmental variability in response to both natural and anthropogenic forcing. Cryptotephra deposits from Icelandic eruptions further contrain sediment chronology in the study, allowing reconstructions of subtle changes in the landscape with excellent chronological control during the late Holocene period of settlement. Additionally, I attempt to improve existing methods for crypto-tephrochronology through the development of new techniques.

Download or read book Holocene Paleo Environmental Reconstruction in Central Tibetan Plateau Inferred from a Lacustrine Sediment Record written by Man-Ching Cheung and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Holocene Paleo-environmental Reconstruction in Central Tibetan Plateau Inferred From a Lacustrine Sediment Record" by Man-ching, Cheung, 張敏青, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Previous studies on reconstructing the paleoclimate on the Tibetan Plateauare commonly based on a single proxy, and have thus limited the usage of their results. Therefore this study was designed firstly to evaluate the applicability of organic carbon isotopes from modern plants in the Tibetan Plateau as a paleo-environmental proxy, and secondly to apply palynology, organic geochemistry and biomarkers to the reconstructions ofpaleo-environmental history of central Tibet. The new, comprehensive records reveal the history of regional precipitation, temperature and vegetation change in responding to Holocene climatic changesin the region. Organic carbon isotope (δ13C) and lipid n-alkanes were measured from plant samples collected from various altitudes and environments across the study area. The δ13C results indicate the importance of availability of water to C3/C4 herbs distribution in this alpine region. The molecular distributions of trees, shrubs, herbs and submergent macrophytes show distinctive features in a number of indices. These indices are considered to be useful for paleo-environmental reconstructions. A 5.8m-long peat core, which were dated back to 95,000 yr BP was obtained from a river valley at an altitude of 4300 m above sea level. The pollen data from the core reveals a sparse herbaceous vegetation in the catchment area during early Holocene, suggesting non-favourable conditions for vegetation growth. The environment became wetter during the early mid-Holocene around 8100-7000 cal. yr BP, and since then a sedge-dominated wetland habitat was developed. This vegetation changed little until about 1100 cal. yr BP; from which an increase of drought-tolerant herbs was indicated by the pollen data, implying a slightly drier condition of the latter part of late Holocene. The pollen record suggests that the optimum precipitation in central Tibet occurred later and lasted longer than that in the East Asian Monsoon region. Finally, bulk sample carbon geochemistry(TOC, δ13C) as well as the biomarkers analysis on n-alkanes and GDGTs as paleo-limnology and paleo-temperature indicators respectively were applied to the core. Before 1500 cal. yr BP, the wetland was dominated by both vascular herbs as suggested by the δ13Cdata and aquatic floating/submerged macrophytes as indicated by mid-chain n-alkanes. The relative proportion of the two sources of organic matter input varied slightly, and vascular herbs increased in two episodes(5400 -4700 and 2800 -2300 cal. yr BP) indicated by the increase of long-chain n-alkanes (>n-C25). Considering of the soil water content variation by the ratios of iGDGTs to bGDGTs, the change between the two plant communities could to be caused by different lake status. GDGTs paleo-temperature reconstruction indicates a warm period from 6700 to 6000 cal. yr BP, which is believed to be the warmest and highly humid in central Tibetan region. Then the temperature decreased towards the late Holocene, consistent with other paleo climate records across the Plateau region, i.e. largely controlled by change of solar insolation. Along the decreasing trend, a warm episode at about 1200 yr BP that inferred from MAAT was suggested corresponding with the North Hemisphere Medieval Warming. DOI: 10.5353/th_b5270537 Subjects: Paleoecology - Tibet, Plateau of Paleoecology - Holocene

Download or read book Holocene Climate and Environmental Variability in NE Germany Inferred from Annually Laminated Lake Sediments written by Nadine Dräger and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the role of natural climate variability under the pressure of human induced changes of climate and landscapes, is crucial to improve future projections and adaption strategies. This doctoral thesis aims to reconstruct Holocene climate and environmental changes in NE Germany based on annually laminated lake sediments. The work contributes to the ICLEA project (Integrated CLimate and Landscape Evolution Analyses). ICLEA intends to compare multiple high-resolution proxy records with independent chronologies from the N central European lowlands, in order to disentangle the impact of climate change and human land use on landscape development during the Lateglacial and Holocene. In this respect, two study sites in NE Germany are investigated in this doctoral project, Lake Tiefer See and palaeolake Wukenfurche. While both sediment records are studied with a combination of high-resolution sediment microfacies and geochemical analyses (e.g. μ-XRF, carbon geochemistry and stable isotopes), detailed proxy understanding mainly focus

Download or read book Reconstructing Late Holocene Sea Level Change and Impacts on Early Settlements in the Lofoten Islands Norway written by Moussa Dia and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study investigates the isolation sequence of several coastal lakes in the Lofoten Islands, northern Norway to understand how relative sea level has changed during the Late Holocene. I use established methods to assess changes in marine influence over the course of the lake records. Three cores ranging from 47 to 174 cm and spanning portions of the last 8000 cal yr BP were analyzed. I measured bulk density, bulk organic matter properties, and elemental profiles from scanning X-ray fluorescence. These characteristics of the sediment reflect detailed changes in salinity and water column conditions as the lakes became isolated. Three distinct lithostratgiraphic units were identified in Inner Borgpollen and represent an open marine phase where the basins were continually inundated marine water (3500 – 1600 cal yr BP), a brackish phase characterized by intermittent marine influence (1600 – 600 cal yr BP), and a tidal phase characterized by restricted marine influence (600 cal yr BP to present). The timing of these phases generally corresponds with previous interpretations of the local relative sea-level history and these records capture sea-level regression during the late Holocene which coincided with human settlements. As a result, changing salinity conditions due to the isolation process may explain the settlement patterns of early human populations between 1600 and 600 cal yr BP.

Download or read book Holocene Climatic Record from Lacustrine Sediments in a Freshwater Lake in the Vestfold Hills Antarctica written by Christian Bronge and published by . This book was released on 1992 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Holocene Climate and Atmospheric Circulation Changes in Northern Fennoscandia written by Christina E. Jonsson and published by . This book was released on 2009 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A High resolution Temperature Record from Lakes of the Lofoten Islands Northwestern Norway Based on a New UK37 Temperature Calibration from in Situ Measurements written by Xiaohui Huang and published by . This book was released on 2011 with total page 105 pages. Available in PDF, EPUB and Kindle. Book excerpt: Water filters and sediment trap samples were collected weekly from late May to early September 2009 from four lakes of the Lofoten archipelago, northwestern Norway, and were used to explore the applicability of the alkenone unsaturation index (UK37) for temperature reconstruction in limnic systems in the area. For the first time, we observed the occurrence of long-chain alkenones (LCAs) within the water columns of lakes in this region. Water filters from two of the four studied lakes contained measurable concentrations of alkenones that were restricted to spring turnover and disappeared with the onset of summer stratification. These results indicate that alkenones in the lake sediment of these lakes reflect biological production and temperature during lake mixing, taking place in late spring to early summer. Measurements from sediment trap material collected over the sampling season combined with water temperature measurements from automated data loggers provide an in situ calibration of the alkenone paleothermometer (Temperature = 33.0 x UK37 + 22.8; N=10; R2=0.95). Notably, this calibration reveals a UK37 sensitivity to temperature (i.e., the slope of the relationship) that is very similar to previous calibrations reported from both marine and lacustrine environments. LCAs can therefore serve as the first quantitative proxy for reconstructing past temperature variability from the Lofoten Islands. Based on this temperature calibration, a high-resolution temperature record was reconstructed over the past millennium, which shows unprecedented lake surface temperature warming during the past decades.

Download or read book Late Glacial and Holocene Climate and Environmental Evolution in the Southern Baltic Iowlands Derived from Varved Lake Sediments written by Florian Ott and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Holocene climate variability is generally characterized by low frequency changes than compared to the last glaciations including the Lateglacial. However, there is vast evidence for decadal to centennial scale oscillations and millennial scale climate trends, which are within and beyond a human lifetime perception, respectively. Within the Baltic realm, a transitional zone between oceanic and continental climate influence, the impact of Holocene and Lateglacial climate and environmental change is currently partly understood. This is mainly attributed to the scarcity of well-dated and high-resolution sediment records and to the lacking continuity of already investigated archives. The aim of this doctoral thesis is to reconstruct Holocene and Late Glacial climate variability on local to (over)regional scales based on varved (annually laminated) sediments from Lake Czechowskie down to annual resolution. This project was carried out within the Virtual Institute for Integrated Climate and Landscape Evolution Analyses (ICLEA) and funded by the Helmholtz Association and the Helmholtz Climate Initiative REKLIM (Regional Climate Change). ICLEA intended to gain a better understanding of climate variability and landscape evolution processes in the Northern Central European lowlands since the last deglaciation. ...

Download or read book Late Glacial and Holocene Climate and Environmental Evolution in the Southern Baltic Iowlands Derived from Varved Lake Sediments written by Florian Ott and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Holocene climate variability is generally characterized by low frequency changes than compared to the last glaciations including the Lateglacial. However, there is vast evidence for decadal to centennial scale oscillations and millennial scale climate trends, which are within and beyond a human lifetime perception, respectively. Within the Baltic realm, a transitional zone between oceanic and continental climate influence, the impact of Holocene and Lateglacial climate and environmental change is currently partly understood. This is mainly attributed to the scarcity of well-dated and high-resolution sediment records and to the lacking continuity of already investigated archives. The aim of this doctoral thesis is to reconstruct Holocene and Late Glacial climate variability on local to (over)regional scales based on varved (annually laminated) sediments from Lake Czechowskie down to annual resolution. This project was carried out within the Virtual Institute for Integrated Climate and Landscape Evolution Analyses (ICLEA) and funded by the Helmholtz Association and the Helmholtz Climate Initiative REKLIM (Regional Climate Change). ICLEA intended to gain a better understanding of climate variability and landscape evolution processes in the Northern Central European lowlands since the last deglaciation. ...

Download or read book 7700 Years of Holocene Climatic Variability in Sermilik Valley Southeast Greenland Inferred from Lake Sediments written by Samuel Hallett Davin and published by . This book was released on 2013 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the latter half of the 20th century until present day there has been an unprecedented rise in global annual mean temperatures accompanied by rising sea levels and a decrease in Northern Hemisphere snow cover, which if it continues will lead to widespread disruption of climate patterns, ecosystems, and present-day landscapes. It is therefore of critical importance to establish an expanded network of paleoclimate records across the globe in order to better assesses how the global climate system has changed in the past, that we may create a metric by which to address modern change. Herein is presented a7,700 years record of Holocene climatic and environmental variability in Sermilik Valley, located on Ammassalik Island, SE Greenland. This objective of this study is to determine the timing of major Holocene climate transitions as expressed in the physical, elemental, and geochemical parameters preserved in the 484 cm sediment record of Lower Sermilik Lake. Major transitions observed in this study include the deglaciation of Sermilik Valley, the onset and termination of the Holocene Climatic Optimum, the transition into neoglacial conditions, and the Little Ice Age.

Download or read book The Holocene Flood History of the Central Alps Reconstructed from Lacustrine Sediments written by Stefanie B. Wirth and published by . This book was released on 2013 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Lacustrine Record of Holocene Glaciation and Radiocarbon Dating of Organic poor Lake Sediment Linn vatnet Spetsbergen Svalbard written by Jeffrey Allan Snyder and published by . This book was released on 1991 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Landscape Evolution and Holocene Climate Change in Mountain Areas of the Northern Highlands Scotland written by Elspeth Reid and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Holocene Climate Variability Based on Two Lacustrine Sediment Sequences from C diz Southern Spain written by Jasmijn van ́t Hoff and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Holocene Climate Change from Fjord and Lake Sediment Core and Seismic Records in Southern Patagonia written by Sverre Liv LeRoy and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: