scholarly journals Paleośrodowiskowe znaczenie zmian tempa i charakteru sedymentacji osadów jeziora Jelonek w Borach Tucholskich = Paleoenvironmental significance of changes in the rate and type of sedimentation in Lake Jelonek within Poland’s Tuchola Pine Forest (Bory Tucholskie)

2020 ◽  
Vol 92 (3) ◽  
pp. 409-422
Author(s):  
Mateusz Kramkowski
Keyword(s):  
Sedimentation Rate ◽  
Sediment Cores ◽  
Rapid Change ◽  
Lacustrine Sediments ◽  
Younger Dryas ◽  
Pine Forest ◽  
Radiocarbon Dates ◽  
The Holocene ◽  
The North ◽  
High Sedimentation

This paper presents the matter of the environmental reconstruction of laminated lacustrine sediments from the Younger Dryas through to the present day, in particular in respect of microlithofacial analysis and sedimentation rate. Lake Jelonek is located within the Tuchola Pine Forest of northern Poland (at 53°45’58N, 18°23’30E). It occupies a subglacial channel immediately adjacent to the Wda Valley. The lake covers 19.9 ha and has a maximum depth of 13.8 m. In 2014, overlapping sediment cores JEL14 (14.23 m) were collected from that deepest part, in order for a full sediment profile including the younger Dryas and the Holocene to be created. Most of the sediment is found to be laminated. Sedimentation rate was reconstructed for the lake, along with microlithofacial variability of different sections of the sediment. The results obtained were related to an age depth model based on 14 AMS radiocarbon dates, varve chronology and the Askja AD 1875 cryptotephra; and was correlated with pollen profiles. The Holocene sediment record of Lake Jelonek exhibits differences between low and high sedimentation rate intervals and varved and non-varved intervals. From the beginning of the Holocene through to the Subatlantic period, sedimentation proved to be a stable phenomenon. However, in the Subatlantic period, the average sedimentation rate increased to 7.7 mm per year from 2.2 mm, with maximum rates even reaching 15.3 mm/year. This period is reflected in a lack of lamination and the appearance of redeposited deposits. These changes prove particularly sensitive to local impact, with distinct alternations of low and high sedimentation rates and varved and non-varved intervals. The most probable drivers for the observed variability reflect a combination of changes of climate plus anthropogenic deforestation during periods of settlement that enhanced the sensitivity of the lake to wind stress. A summary of all analyses allowed for the identification of periods of rapid change in sedimentation, and – indirectly – for the reproduction of changes in the water level and anthropopressure in and around Lake Jelonek. Such results contribute to a better understanding of local influences on fluctuations in lake sedimentation processes characteristic for the north of Poland, but also Central Europe more widely.

scholarly journals The role of Northeast Pacific meltwater events in deglacial climate change

2020 ◽  
Vol 6 (9) ◽  
pp. eaay2915 ◽  
Author(s):  
Summer K. Praetorius ◽  
Alan Condron ◽  
Alan C. Mix ◽  
Maureen H. Walczak ◽  
Jennifer L. McKay ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
North Pacific ◽  
Sediment Cores ◽  
Younger Dryas ◽  
Columbia River ◽  
Sea Surface ◽  
Subsurface Water ◽  
Last Deglaciation ◽  
Northeast Pacific ◽  
The North

Columbia River megafloods occurred repeatedly during the last deglaciation, but the impacts of this fresh water on Pacific hydrography are largely unknown. To reconstruct changes in ocean circulation during this period, we used a numerical model to simulate the flow trajectory of Columbia River megafloods and compiled records of sea surface temperature, paleo-salinity, and deep-water radiocarbon from marine sediment cores in the Northeast Pacific. The North Pacific sea surface cooled and freshened during the early deglacial (19.0-16.5 ka) and Younger Dryas (12.9-11.7 ka) intervals, coincident with the appearance of subsurface water masses depleted in radiocarbon relative to the sea surface. We infer that Pacific meltwater fluxes contributed to net Northern Hemisphere cooling prior to North Atlantic Heinrich Events, and again during the Younger Dryas stadial. Abrupt warming in the Northeast Pacific similarly contributed to hemispheric warming during the Bølling and Holocene transitions. These findings underscore the importance of changes in North Pacific freshwater fluxes and circulation in deglacial climate events.

Quaternary Glaciers and Climate on Cerro Chirripó, Costa Rica

2000 ◽  
Vol 54 (1) ◽  
pp. 24-37 ◽  
Author(s):  
Kenneth H. Orvis ◽  
Sally P. Horn
Keyword(s):  
Costa Rica ◽  
High Altitude ◽  
Central America ◽  
Younger Dryas ◽  
Glacial Geomorphology ◽  
Radiocarbon Dates ◽  
Tropical Glaciers ◽  
The North ◽  
Organic Sediments ◽  
Lower Limits

Glacial lake sediments and glacial geomorphology in Valle de las Morrenas, a glacial trough on the north face of Cerro Chirripó, Costa Rica, provide evidence on high-altitude Pleistocene conditions in Central America. The most recent glacier in the valley (Chirripó stage I) receded very rapidly near the end of the Younger Dryas chronozone. Radiocarbon dates on basal organic sediments from lakes beneath upper, middle, and lower limits of that glacier fall close together, and two-sigma calibrated ages overlap for the period 9700–9600 cal yr B.P. Earliest datable transition sediments from the central lake date to 12,360–11,230 cal yr B.P. Larger, older moraines, and associated trimlines, allowed reconstruction of three paleoglaciers (Chirripó stages II, III, and IV). Computer analysis of hypsometry using published tropical-glacier vertical mass balance profiles yields ELAs of 3506–3523, 3515–3537, and 3418–3509 m, respectively; Chirripó II ELA-estimate positions applied to Chirripó I yield an ELA of 3538–3546 m. We infer minimal temperature depressions of 7.4–8.0°C for the Chirripó I–IV stages. Modeling the behavior of modern tropical glaciers yields basinwide net accumulation estimates of 440–620, 550–830, and 960–1760 mm yr−1 for the Chirripó II, III, and IV stages.

scholarly journals Of Meuse and Man: the geomorphogenetic and archaeological predictive maps of the Dutch Meuse valley

2017 ◽  
Vol 96 (2) ◽  
pp. 183-196 ◽  
Author(s):  
R.F.B. Isarin ◽  
E. Rensink ◽  
G.R. Ellenkamp ◽  
E. Heunks
Keyword(s):  
Land Use ◽  
Younger Dryas ◽  
The Holocene ◽  
The North ◽  
Aeolian Geomorphology ◽  
Landscape Processes ◽  
Cultural Themes ◽  
Human Habitation ◽  
The Impact ◽  
First Time

AbstractFor the first time, geomorphology and archaeology are combined for a 165 km long stretch of the Meuse river, resulting in a geomorphogenetic map (GKM) and a series of archaeological predictive maps (AVM). The maps cover the central part the Meuse valley, located in the province of Limburg between Mook in the north and Eijsden in the south. The area consists of fluvial and aeolian landforms of the Holocene Meuse floodplain and Younger Dryas aged terraces along it, spanning a period of approximately 15,000 years of landscape genesis and human habitation. The GKM more clearly discriminates between map units of Younger Dryas and early Holocene age than in previous mappings of the Meuse valley. The AVM series provide predictive information on the location of sites for four distinct consecutive archaeological periods and four main cultural themes. The maps contribute to a better understanding of landscape processes (fluvial and aeolian geomorphology and the impact of man on river behaviour), and the possibilities for human habitation and land use in prehistoric and historic times.

An Integrated Latest Quaternary (Stage 3 to Present) Paleoclimatic and Paleoceanographic Record from Offshore Northern New Zealand

1995 ◽  
Vol 44 (2) ◽  
pp. 283-293 ◽  
Author(s):  
Ian C. Wright ◽  
Matt S. McGlone ◽  
Campbell S. Nelson ◽  
Brad J. Pillans
Keyword(s):  
New Zealand ◽  
Sea Level ◽  
Vegetation History ◽  
Sediment Cores ◽  
Subsurface Water ◽  
Deep Sea Sediment ◽  
The Holocene ◽  
The North ◽  
Paleoclimatic Changes ◽  
Stage 4

AbstractPaleoceanographic and onshore paleoclimatic changes during the last 59,000 yr are established from three deep-sea sediment cores off northeast New Zealand using an integrated log of sediment texture, CaCO3 content, palynology, and planktonic and benthic foraminiferal δ18O and δ13C data, together with dated silicic tephras. These records from the isotopic stage 4-3 boundary to the present record northern New Zealand vegetation history, changes in a subsidiary equatorward flow of Circumpolar Deep Water, and sea-surface temperatures (SSTs) for subtropical water (STW) between latitudes 36°42′ and 35°51′S. Relative to the Holocene, isotopically derived SSTs record average changes of +2°C, -2°C, and -2°C for the 59,000-43,000, 43,000-24,000, and 24,000-12,000 yr time slices, respectively. The apparent +2°C warming for the 59,000-43,000 yr period is interpreted to reflect changes in the dominant depth habitat of Globigerina bulloides in response to upwelling. A -2°C cooling of SSTs during isotope stage 2 is interpreted, in part, to reflect upwelling of cool subsurface water resulting from strong and persistent westerly airflow across New Zealand, with the concomitant enhanced surface-water production of CaCO3. Onshore, vegetation consistent with these changes are recorded, with full conifer-hardwood forest prior to 43,000 yr, followed by a change to vegetation implying cooler and drier conditions between 43,000 and 12,000 yr, and a subsequent return to full forest during the Holocene. The sequence of biopelagic and hemipelagic sedimentation observed within these cores reflect oscillation of sea level about a threshold eustatic level that controls the transport of terrigenous detritus offshore. Local variations and interplay of the regional oceanography and morphology and tectonism of the continental shelf will dictate that, relative to present sea level, this threshold eustatic sea level will vary in depth, and hence age, along a continental margin. Data from the New Zealand region reveal an extremely steep meridional thermal gradient across the southern and central New Zealand region during the last glaciation with minor cooling of STW to the north, apart from localized nearshore upwelling zones, but pronounced cooling of subantarctic water to the south of the subtropical convergence zone.

New Radiocarbon Dates for the Vedde Ash and the Saksunarvatn Ash from Western Norway

1996 ◽  
Vol 45 (2) ◽  
pp. 119-127 ◽  
Author(s):  
Hilary H. Birks ◽  
Steinar Gulliksen ◽  
Haflidi Haflidason ◽  
Jan Mangerud ◽  
Göran Possnert
Keyword(s):  
Lake Sediment ◽  
Younger Dryas ◽  
Plant Macrofossils ◽  
Early Holocene ◽  
Radiocarbon Dates ◽  
Terrestrial Plant ◽  
Radiocarbon Age ◽  
The North ◽  
Western Norway ◽  
Ams Dates

AbstractThe Vedde Ash Bed (mid-Younger Dryas) and the Saksunarvatn Ash (early Holocene) are important regional stratigraphic event markers in the North Atlantic, the Norwegian Sea, and the adjacent land area. It is thus essential to date them as precisely as possible. The occurrence of the Saksunarvatn Ash is reported for the first time from western Norway, and both tephras are dated precisely by AMS analyses of terrestrial plant material and lake sediment at Kråkenes. The Vedde Ash has been previously dated at sites in western Norway to about 10,600 yr B.P. It is obvious in the Younger Dryas sediments at Kråkenes, and its identity is confirmed geochemically. The mean of four AMS dates of samples of Salix herbacea leaves adjacent to the tephra is 10,310 ± 50 yr B.P. The Saksunarvatn Ash is not visible in the early Holocene lake sediment at Kråkenes. After removal of organic material and diatoms, the identity of the tephra particles was confirmed geochemically, and their stratigraphic concentration was estimated. From curve matching of a series of seven AMS dates of terrestrial plant macrofossils and whole sediment, the radiocarbon age of the ash is 8930–9060 yr B.P., corresponding to an age of 9930–10,010 cal yr B.P. (7980–8060 cal yr B.C.).

On the Estimation of Deep Atlantic Ventilation from Fossil Radiocarbon Records. I. Modern Reference Estimates

2021 ◽  
Author(s):  
Olivier Marchal ◽  
Ning Zhao
Keyword(s):  
North Atlantic ◽  
Sediment Cores ◽  
Deep Ocean ◽  
South Atlantic ◽  
Ice Age ◽  
The South ◽  
Meridional Transport ◽  
Radiocarbon Dates ◽  
Geostrophic Balance ◽  
The North

AbstractRadiocarbon dates of fossil carbonates sampled from sediment cores and the seafloor have been used to infer that deep ocean ventilation during the last ice age was different from today. In this first of paired papers, the time-averaged abyssal circulation in the modern Atlantic is estimated by combining a hydrographic climatology, observational estimates of volume transports, Argo float velocities at 1000 m, radiocarbon data, and geostrophic dynamics. Different estimates of modern circulation, obtained from different prior assumptions about the abyssal flow and different errors in the geostrophic balance, are produced for use in a robust interpretation of fossil records in terms of deviations from the present-day flow, which is undertaken in the second paper.For all estimates, the meridional transport integrated zonally and averaged over a hemisphere, 〈Vk〉, is southward between 1000-4000 m in both hemispheres, northward between 4000-5000 m in the South Atlantic, and insignificant between 4000-5000 m in the North Atlantic. Estimates of 〈Vk〉 obtained from two distinct prior circulations - one based on a level of no motion at 4000 m and one based on Argo oat velocities at 1000 m - become statistically indistinguishable when Δ14C data are considered. The transport time scale, defined as τk = /〈Vk〉, where is the volume of the kth layer, is estimated to about a century between 1000-3000 m in both the South and North Atlantic, 124±9 yr (203±23 yr) between 3000-4000 m in the South (North) Atlantic, and 269±115 yr between 4000-5000 m in the South Atlantic.

scholarly journals The Dawn of the Mesolithic on the Plains of Poland

2020 ◽  
Vol 33 (3) ◽  
pp. 325-383
Author(s):  
Tomasz Płonka ◽  
Dariusz Bobak ◽  
Michał Szuta
Keyword(s):  
Population Dynamics ◽  
Bayesian Analysis ◽  
Cultural Landscape ◽  
Cultural Patterns ◽  
Radiocarbon Dates ◽  
The Holocene ◽  
The North

AbstractIn this article we take a fresh look at the population dynamics of the Polish Plain in the transition from the Pleistocene to the Holocene, using Bayesian analysis and modelling of radiocarbon dates, and contrast the results with data from the North German Plain. We argue against simple adaptationalist models and instead see the cultural landscape as a complex patchwork of old forms and the emerging new traits of the early Mesolithic. We argue that the Mesolithic directly follows the Final Palaeolithic on the Polish Plain, without the chronological hiatus of 150–300 years that is often assumed for that region; while, by contrast, the two cultural patterns—Final Palaeolithic and microlith-based Mesolithic—overlapped significantly in time on the adjacent North German Plain.

Rapid Ice Margin Fluctuations during the Younger Dryas in the Tropical Andes

2000 ◽  
Vol 54 (3) ◽  
pp. 328-338 ◽  
Author(s):  
Donald T. Rodbell ◽  
Geoffrey O. Seltzer
Keyword(s):  
Younger Dryas ◽  
Late Glacial ◽  
Tropical Andes ◽  
Radiocarbon Dates ◽  
Peruvian Andes ◽  
Southern Peru ◽  
Ice Cap ◽  
The North ◽  
Glacier Advance ◽  
Lake Deposits

Radiocarbon dated lacustrine sequences in Perú show that the chronology of glaciation during the late glacial in the tropical Andes was significantly out-of-phase with the record of climate change in the North Atlantic region. Fluvial incision of glacial-lake deposits in the Cordillera Blanca, central Perú, has exposed a glacial outwash gravel; radiocarbon dates from peat stratigraphically bounding the gravel imply that a glacier advance culminated between ∼11,280 and 10,990 14C yr B.P.; rapid ice recession followed. Similarly, in southern Perú, ice readvanced between ∼11,500 and 10,900 14C yr B.P. as shown by a basal radiocarbon date of ∼10,870 14C yr B.P. from a lake within 1 km of the Quelccaya Ice Cap. By 10,900 14C yr B.P. the ice front had retreated to nearly within its modern limits. Thus, glaciers in central and southern Perú advanced and retreated in near lockstep with one another. The Younger Dryas in the Peruvian Andes was apparently marked by retreating ice fronts in spite of the cool conditions that are inferred from the ∂18O record of Sajama ice. This retreat was apparently driven by reduced precipitation, which is consistent with interpretations of other paleoclimatic indicators from the region and which may have been a nonlinear response to steadily decreasing summer insolation.

OSL dating of an inland dune along the lower River Scheldt near Aard (East Flanders, Belgium)

2011 ◽  
Vol 90 (1) ◽  
pp. 23-29 ◽  
Author(s):  
F. Bogemans ◽  
D. Vandenberghe
Keyword(s):  
Direct Determination ◽  
Younger Dryas ◽  
Optically Stimulated Luminescence ◽  
Osl Dating ◽  
Luminescence Dating ◽  
Radiocarbon Dates ◽  
The Holocene ◽  
Dune Sands ◽  
Optically Stimulated Luminescence Dating ◽  
Aeolian Dunes

AbstractThe chronostratigraphic position of aeolian dunes in East Flanders (Belgium) has been under debate for decades. Until now, the only available age information consisted of a limited number of radiocarbon dates, which provided indirect sediment deposition chronologies. This paper reports on the first direct determination, by quartz-based single-aliquot optically stimulated luminescence dating, of the time that dune sands were deposited along the Lower River Scheldt in Belgium. The sediments are dated at 12.0±0.9 ka (n = 5), which confirms that the time of inland dune formation in East Flanders dates from the Younger Dryas period and should not be constrained to the Holocene.

scholarly journals Soils in Karst Sinkholes Record the Holocene History of Local Forest Fires at the North of European Russia

Forests ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1268
Author(s):  
Nikita Mergelov ◽  
Dmitry Petrov ◽  
Elya Zazovskaya ◽  
Andrey Dolgikh ◽  
Alexandra Golyeva ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Forest Fires ◽  
Soil Formation ◽  
Soil Morphology ◽  
Deep Soil ◽  
Radiocarbon Dates ◽  
The Holocene ◽  
The North ◽  
Peat Deposits

Despite the abundance of charcoal material entrapped in soils, they remain relatively less studied pyrogenic archives in comparison to the sedimentary paleofire records (e.g., lacustrine and peat deposits), and that is especially the case in most of Russia’s territory. We report here on the deep soil archives of the Holocene forest fires from the Pinega District of the Arkhangelsk region (64.747° N, 43.387° E). Series of buried soil profiles separated by charcoal layers and clusters were revealed in specific geomorphological traps represented by the active and paleokarst subsidence sinkholes on sulfate rocks overlaid by glacial and fluvial deposits. We combine the study of soil morphology and stratigraphy with a set of radiocarbon data on charcoal and soil organic matter, as well as the anthracomass analysis, to extract a set of paleoenvironmental data. A total of 45 radiocarbon dates were obtained for the macrocharcoal material and the soil organic matter. The maximum temporal “depth” of archives estimated from the radiocarbon dating of macrocharcoal reached 10,260 ± 35 cal yr BP. Soil formation with Podzols established at the inter-pyrogenic stages repeatedly reproduced within the period of ten thousand years, while the dominant tree species was Pinus sp. According to the macrocharcoal data, the intervals between fires have shortened in the last thousand years. Dendrochronological estimates suggest the occurrence of fires in almost every decade of the 20th and early 21st centuries. This is the first study of the millennia-scale soil record of forest fires in this particular region of Russia.

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