scholarly journals Illuminating Intcal During the Younger Dryas

Radiocarbon ◽  
2020 ◽  
Vol 62 (4) ◽  
pp. 883-889 ◽  
Author(s):  
Frederick Reinig ◽  
Adam Sookdeo ◽  
Jan Esper ◽  
Michael Friedrich ◽  
Giulia Guidobaldi ◽  
...  
Keyword(s):  
Environmental Change ◽  
Calibration Curve ◽  
Younger Dryas ◽  
Late Glacial ◽  
Precision Data ◽  
The Past ◽  
Climate And Environmental Change ◽  
Absolute Dating ◽  
High Precision Data ◽  
Geochronological Dating

ABSTRACTAs the worldwide standard for radiocarbon (14C) dating over the past ca. 50,000 years, the International Calibration Curve (IntCal) is continuously improving towards higher resolution and replication. Tree-ring-based 14C measurements provide absolute dating throughout most of the Holocene, although high-precision data are limited for the Younger Dryas interval and farther back in time. Here, we describe the dendrochronological characteristics of 1448 new 14C dates, between ~11,950 and 13,160 cal BP, from 13 pines that were growing in Switzerland. Significantly enhancing the ongoing IntCal update (IntCal20), this Late Glacial (LG) compilation contains more annually precise 14C dates than any other contribution during any other period of time. Thus, our results now provide unique geochronological dating into the Younger Dryas, a pivotal period of climate and environmental change at the transition from LG into Early Holocene conditions.

scholarly journals Prospecting Glacial Ages and Paleoclimatic Reconstructions Northeastward of Nevado Coropuna (16° S, 73° W, 6377 m), Arid Tropical Andes

Geosciences ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 307 ◽  
Author(s):  
Jose Úbeda ◽  
Martí Bonshoms ◽  
Joshua Iparraguirre ◽  
Lucía Sáez ◽  
Ramón de la Fuente ◽  
...  
Keyword(s):  
Younger Dryas ◽  
Equilibrium Line ◽  
Tropical Andes ◽  
Maximum Extension ◽  
The Past ◽  
Volcanic Processes ◽  
Absolute Dating ◽  
Bolivian Altiplano ◽  
Chlorine 36

This work investigates the timing, paleoclimatic framework and inter-hemispheric teleconnections inferred from the glaciers last maximum extension and the deglaciation onset in the Arid Tropical Andes. A study area was selected to the northeastward of the Nevado Coropuna, the volcano currently covered by the largest tropical glacier on Earth. The current glacier extent, the moraines deposited in the past and paleoglaciers at their maximum extension have been mapped. The present and past Equilibrium Line Altitudes (ELA and paleoELA) have been reconstructed and the chlorine-36 ages have been calculated, for preliminary absolute dating of glacial and volcanic processes. The paleoELA depression, the thermometers installed in the study area and the accumulation data previously published allowed development of paleotemperature and paleoprecipitation models. The Coropuna glaciers were in maximum extension (or glacial standstill) ~20–12 ka ago (and maybe earlier). This last maximum extension was contemporary to the Heinrich 2–1 and Younger Dryas events and the Tauca and Coipasa paleolake transgressions on Bolivian Altiplano. The maximum paleoELA depression (991 m) shows a colder (−6.4 °C) and moister climate with precipitation ×1.2–×2.8 higher than the present. The deglaciation onset in the Arid Tropical Andes was 15–11 ka ago, earlier in the most southern, arid, and low mountains and later in the northernmost, less arid, and higher mountains.

scholarly journals How dry was the Younger Dryas? Evidence from a coupled <i>δ</i><sup>2</sup>H–<i>δ</i><sup>18</sup>O biomarker paleohygrometer applied to the Gemündener Maar sediments, Western Eifel, Germany

2019 ◽  
Vol 15 (2) ◽  
pp. 713-733 ◽  
Author(s):  
Johannes Hepp ◽  
Lorenz Wüthrich ◽  
Tobias Bromm ◽  
Marcel Bliedtner ◽  
Imke Kathrin Schäfer ◽  
...  
Keyword(s):  
Isotope Composition ◽  
Younger Dryas ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Leaf Water ◽  
Early Holocene ◽  
Unexpected Finding ◽  
Temperature Dependent ◽  
The Past ◽  
Natural Climate

Abstract. Causes of the Late Glacial to Early Holocene transition phase and particularly the Younger Dryas period, i.e. the major last cold spell in central Europe during the Late Glacial, are considered to be keys for understanding rapid natural climate change in the past. The sediments from maar lakes in the Eifel, Germany, have turned out to be valuable archives for recording such paleoenvironmental changes. For this study, we investigated a Late Glacial to Early Holocene sediment core that was retrieved from the Gemündener Maar in the Western Eifel, Germany. We analysed the hydrogen (δ2H) and oxygen (δ18O) stable isotope composition of leaf-wax-derived lipid biomarkers (n-alkanes C27 and C29) and a hemicellulose-derived sugar biomarker (arabinose), respectively. Both δ2Hn-alkane and δ18Osugar are suggested to reflect mainly leaf water of vegetation growing in the catchment of the Gemündener Maar. Leaf water reflects δ2H and δ18O of precipitation (primarily temperature-dependent) modified by evapotranspirative enrichment of leaf water due to transpiration. Based on the notion that the evapotranspirative enrichment depends primarily on relative humidity (RH), we apply a previously introduced “coupled δ2Hn-alkane–δ18Osugar paleohygrometer approach” to reconstruct the deuterium excess of leaf water and in turn Late Glacial–Early Holocene RH changes from our Gemündener Maar record. Our results do not provide evidence for overall markedly dry climatic conditions having prevailed during the Younger Dryas. Rather, a two-phasing of the Younger Dryas is supported, with moderate wet conditions at the Allerød level during the first half and drier conditions during the second half of the Younger Dryas. Moreover, our results suggest that the amplitude of RH changes during the Early Holocene was more pronounced than during the Younger Dryas. This included the occurrence of a “Preboreal Humid Phase”. One possible explanation for this unexpected finding could be that solar activity is a hitherto underestimated driver of central European RH changes in the past.

Revised ‘absolute’ dating of the early Mesolithic site of Star Carr, North Yorkshire, in the light of changes in the early Holocene tree-ring chronology

Antiquity ◽  
2000 ◽  
Vol 74 (284) ◽  
pp. 304-307 ◽  
Author(s):  
Petra Dark
Keyword(s):  
Environmental Change ◽  
Tree Ring ◽  
Calibration Curve ◽  
Early Holocene ◽  
Tree Ring Chronology ◽  
Absolute Dating ◽  
The Absolute ◽  
Holocene Environmental Change ◽  
Radiocarbon Calibration

Recent revision of the radiocarbon calibration curve for the early Holocene has implications for the ‘absolute’ date of Mesolithic sites such as Star Carr, and for their relationship to the timescale of early Holocene environmental change.

scholarly journals Revisions and Extension of the Hohenheim Oak and Pine Chronologies: New Evidence About the Timing of the Younger Dryas/Preboreal Transition

Radiocarbon ◽  
1998 ◽  
Vol 40 (3) ◽  
pp. 1107-1116 ◽  
Author(s):  
Marco Spurk ◽  
Michael Friedrich ◽  
Jutta Hofmann ◽  
Sabine Remmele ◽  
Burkhard Frenzel ◽  
...  
Keyword(s):  
Calibration Curve ◽  
Younger Dryas ◽  
Ice Cores ◽  
Early Holocene ◽  
Proxy Data ◽  
The Past ◽  
Varve Chronology ◽  
New Evidence ◽  
Radiocarbon Calibration

Oak and pine samples housed at the Institute of Botany, University of Hohenheim, are the backbone of the early Holocene part of the radiocarbon calibration curve, published in 1993 (Becker 1993; Kromer and Becker 1993; Stuiver and Becker 1993; Vogel et al. 1993). Since then the chronologies have been revised. The revisions include 1) the discovery of 41 missing years in the oak chronology and 2) a shift of 54 yr for the oldest part back into the past. The oak chronology was also extended with new samples as far back as 10,429 BP (8480 BC). In addition, the formerly tentatively dated pine chronology (Becker 1993) has been rebuilt and shifted to an earlier date. It is now positioned by 14C matching at 11,871-9900 BP (9922–7951 BC) with an uncertainty of ±20 yr (Kromer and Spurk 1998). With these new chronologies the 14C calibration curve can now be corrected, eliminating the discrepancy in the dating of the Younger Dryas/Preboreal transition between the proxy data of the GRIP and GISP ice cores (Johnsen et al. 1992; Taylor et al. 1993), the varve chronology of Lake Gościąż (Goslar et al. 1995) and the pine chronology (Becker, Kromer and Trimborn 1991).

Late-Glacial to Holocene Changes in Winds, Upwelling, and Seasonal Production of the Northern California Current System

1992 ◽  
Vol 38 (3) ◽  
pp. 359-370 ◽  
Author(s):  
Constance Sancetta ◽  
Michell Lyle ◽  
Linda Heusser ◽  
Rainer Zahn ◽  
J.Platt Bradbury
Keyword(s):  
Late Pleistocene ◽  
Climate Model ◽  
Current System ◽  
Younger Dryas ◽  
California Current ◽  
Late Glacial ◽  
California Current System ◽  
The Past ◽  
Northern California Current ◽  
Continental Interior

AbstractA core 120 km off the coast of southern Oregon was examined for changes in lithology, diatoms, and pollen over the past 30,000 yr. Primary production during the late Pleistocene was about half that of the Holocene. Evidence from diatoms and pollen indicates that summer upwelling was much weaker, implying an absence of strong northerly winds. Early Pliocene diatoms found throughout the late Pleistocene section were probably derived from diatomites east of the Cascades and provide evidence for strong easterly winds over a dry continental interior. The findings verify predictions of a climate model based on glacial maximum conditions. There is no compelling evidence for a climatic reversal corresponding to the European Younger Dryas chron. During the early Holocene (9000−7000 yr B.P.) there may have been years when winds were insufficiently strong to support upwelling, so that warm stratified waters lay closer to the coast.

Fluctuations of Outlet and Valley Glaciers in the Southern Andes (Argentina) during the Past 13,000 Years

1999 ◽  
Vol 51 (3) ◽  
pp. 238-247 ◽  
Author(s):  
Gerd Wenzens
Keyword(s):  
Younger Dryas ◽  
Late Glacial ◽  
The South ◽  
Southern Andes ◽  
Outlet Glacier ◽  
The Holocene ◽  
The Past ◽  
Late Glacial And Holocene ◽  
Glacial Time

AbstractIn the southern Argentine Andes, ten advances of valley glaciers were used to reconstruct the late-glacial and Holocene glacier history. The accumulation areas of these glaciers lie in the Precordillera and are thus independent of fluctuations of the South Patagonian Icefield. Like the Viedma outlet glacier, the valley glaciers advanced three times during late-glacial time (14,000–10,000 yr B.P.). The youngest advance correlates with the Younger Dryas Stade, based on two minimum AMS14C dates of 9588 and 9482 yr B.P. The second oldest advance occurred before 11,800 yr B.P. During the first half of the Holocene, (ca. 10,000–5000 yr B.P.), advances culminated about 8500, 8000–7500, and 5800–5500 yr B.P. During the second half of the Holocene, advances occurred between ca. 4500 and 4200 yr B.P., as well as between 3600 and 3300 yr B.P. In the Rı́o Cóndor valley three subsequent advances have been identified.

Study of LEAP® 5000 Deadtime and Precision via Silicon Pre-Sharpened-Microtip™ Standard Specimens

2021 ◽  
pp. 1-19
Author(s):  
Ty J. Prosa ◽  
Edward Oltman
Keyword(s):  
Mass Spectrum ◽  
Error Propagation ◽  
Atom Probe ◽  
Silicon Isotope ◽  
Precision Data ◽  
The Past ◽  
Standard Specimens ◽  
Dataset Size ◽  
High Precision Data ◽  
Counting Statistics

Abstract Atom probe tomography (APT) is a technique that has expanded significantly in terms of adoption, dataset size, and quality during the past 15 years. The sophistication used to ensure ultimate analysis precision has not kept pace. The earliest APT datasets were small enough that deadtime and background considerations for processing mass spectrum peaks were secondary. Today, datasets can reach beyond a billion atoms so that high precision data processing procedures and corrections need to be considered to attain reliable accuracy at the parts-per-million level. This paper considers options for mass spectrum ranging, deadtime corrections, and error propagation as applied to an extrinsic-silicon standard specimen to attain agreement for silicon isotopic fraction measurements across multiple instruments, instrument types, and acquisition conditions. Precision consistent with those predicted by counting statistics is attained showing agreement in silicon isotope fraction measurements across multiple instruments, instrument platforms, and analysis conditions.

scholarly journals Radiocarbon Calibration by Means of Varves Versus 14C Ages of Terrestrial Macrofossils from Lake Gościąż and Lake Perespilno, Poland

Radiocarbon ◽  
2000 ◽  
Vol 42 (3) ◽  
pp. 335-348 ◽  
Author(s):  
Tomasz Goslar ◽  
Maurice Arnold ◽  
Nadine Tisnerat-Laborde ◽  
Christine Hatté ◽  
Martine Paterne ◽  
...  
Keyword(s):  
Calibration Curve ◽  
Younger Dryas ◽  
Late Glacial ◽  
Cariaco Basin ◽  
Rapid Decline ◽  
Radiocarbon Dates ◽  
Radiocarbon Calibration

This paper presents radiocarbon dates of terrestrial macrofossils from Lakes Gościąż and Perespilno, Poland. These data agree very well with most of the German pine calibration curve. In the Late Glacial, they generally agree with the data from Lake Suigetsu, Japan, and indicate constant or even increasing 14C age between 12.9 and 12.7 ka BP, rapid decline of 14C age around 12.6 ka BP, and a long plateau 10,400 14C BP around 12 ka BP. Correlation with corals and data from the Cariaco basin seems to support the concept of site-speficic, constant values of reservoir correction, in contradiction to those introduced in the INTCAL98 calibration. Around the Allerød/Younger Dryas boundary our data strongly disagree with those from the Cariaco basin, which reflects large discrepancy between calendar chronologies at that period. The older sequence from Lake Perespilno indicates two periods of rapid decline in 14C age, around 14.2 and 13.9 ka BP.

scholarly journals Chronostratigraphy of Late Glacial aeolian activity in SW Poland – A case study from the Niemodlin Plateau

2020 ◽  
Vol 47 (1) ◽  
pp. 124-137
Author(s):  
Piotr Moska ◽  
Zdzisław Jary ◽  
Robert Jan Sokołowski ◽  
Grzegorz Poręba ◽  
Jerzy Raczyk ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Younger Dryas ◽  
Soil Formation ◽  
Late Glacial ◽  
Sedimentary Environments ◽  
Three Samples ◽  
Aeolian Activity ◽  
Dating Methods ◽  
Absolute Dating ◽  
Sw Poland

AbstractThe stratigraphy of Late Pleniglacial and Late Glacial fluvio-to-aeolian succession was investigated in two sites located at the Niemodlin Plateau, SW Poland. Lithofacial analysis was used for the reconstruction of sedimentary environments. An absolute chronology for climatic change and the resulting environmental changes were determined based on optically stimulated luminescence (OSL – nine samples) and radiocarbon (three samples) dating methods. Four phases of changes in sedimentary environments were established. The first depositional phase correlates with the Last Permafrost Maximum (24−17 ka) based on the type and size of the periglacial structures, which aggraded under continuous permafrost conditions. During 17.5−15.5 ka (upper Late Pleniglacial), a stratigraphic gap was detected, owing to a break in the deposition on the interfluve area. The second depositional phase took place during 15.5−13.5 ka. During this phase, the first part of the dune formation (Przechód site) and fluvio-aeolian cover (Siedliska site) was deposited. The sedimentary processes continued throughout the entire Bølling interstadial and Older Dryas. In the third phase (Allerød interstadial), soil formation took place. At the Siedliska site, palaeosol represented Usselo soil type, whereas at the Przechód site, there was a colluvial type of soil. The last phase (Younger Dryas) is represented by the main phase of dune formation in both sites. After the Younger Dryas, no aeolian activity was detected. High compliance with both absolute dating methods was noticed.

Constraining past global tropospheric methane budgets with carbon and hydrogen isotope ratios in ice

2007 ◽  
Vol 365 (1856) ◽  
pp. 1793-1828 ◽  
Author(s):  
Michael Whiticar ◽  
Hinrich Schaefer
Keyword(s):  
Younger Dryas ◽  
Late Glacial ◽  
Mixing Ratio ◽  
Mass Balances ◽  
Late Glacial Period ◽  
The Past ◽  
Methane Budget ◽  
Hydrogen Isotope Ratios ◽  
Palaeoenvironmental Conditions ◽  
Carbon And Hydrogen Isotope

Upon closer inspection, the classical view of the synchronous relationship between tropospheric methane mixing ratio and Greenland temperature observed in ice samples reveals clearly discernable variations in the magnitude of this response during the Late Pleistocene (<50 kyr BP). During the Holocene this relationship appears to decouple, indicating that other factors have modulated the methane budget in the past 10 kyr BP. The δ 13 CH 4 and δD-CH 4 of tropospheric methane recorded in ice samples provide a useful constraint on the palaeomethane budget estimations. Anticipated changes in palaeoenvironmental conditions are recorded as changes in the isotope signals of the methane precursors, which are then translated into past global δ 13 CH 4 and δD-CH 4 signatures. We present the first methane budgets for the late glacial period that are constrained by dual stable isotopes. The overall isotope variations indicate that the Younger Dryas (YD) and Preindustrial Holocene have methane that is 13 C- and 2 H-enriched, relative to Modern. The shift is small for δ 13 CH 4 (approx. 1‰) but greater for δD-CH 4 (approx. 9‰). The YD δ 13 CH 4 –δD-CH 4 record shows a remarkable relationship between them from 12.15 to 11.52 kyr BP. The corresponding C- and H-isotope mass balances possibly indicate fluctuating emissions of thermogenic gas. This δ 13 CH 4 –δD-CH 4 relationship breaks down during the YD–Preboreal transition. In both age cases, catastrophic releases of hydrates with Archaeal isotope signatures can be ruled out. Thermogenic clathrate releases are possible during the YD period, but so are conventional natural gas seepages.

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