Cirque glacier activity in arctic Norway during the last deglaciation

2007 ◽  
Vol 68 (3) ◽  
pp. 387-399 ◽  
Author(s):  
Øyvind Paasche ◽  
Svein Olaf Dahl ◽  
Jostein Bakke ◽  
Reidar Løvlie ◽  
Atle Nesje
Keyword(s):  
Regional Distribution ◽  
Lacustrine Sediments ◽  
Younger Dryas ◽  
Last Deglaciation ◽  
Visual Interpretation ◽  
Dry Period ◽  
Equilibrium Line Altitude ◽  
Glacial Retreat ◽  
Magnetic Parameters ◽  
The Last Deglaciation

AbstractNumerous cirques of the Lofoten–Vesterålen archipelago in northern Norway have distinct moraine sequences that previously have been assigned to the Allerød-Younger Dryas (∼ 13,400 to 11,700 yr BP) interval, constraining the regional distribution of the equilibrium-line altitude (ELA) of cirque and valley glaciers. Here we present evidence from a once glacier-fed lake on southern Andøya that contests this view. Analyses of radiocarbon dated lacustrine sediments including rock magnetic parameters, grain size, organic matter, dry bulk density and visual interpretation suggest that no glacier was present in the low-lying cirque during the Younger Dryas-Allerød. The initiation of the glacial retreat commenced with the onset of the Bølling warming (∼ 14,700 yr BP) and was completed by the onset of Allerød Interstade (∼ 13,400 yr BP). The reconstructed glacier stages of the investigated cirque coincide with a cool and dry period from ∼ 17,500 to 14,700 yr BP and a somewhat larger Last Glacial Maximum (LGM) advance possibly occurring between ∼ 21,050 and 19,100 yr BP.

The chronology of the last Deglaciation: Implications to the cause of the Younger Dryas Event

1988 ◽  
Vol 3 (1) ◽  
pp. 1-19 ◽  
Author(s):  
W. S. Broecker ◽  
M. Andree ◽  
W. Wolfli ◽  
H. Oeschger ◽  
G. Bonani ◽  
...  
Keyword(s):  
Younger Dryas ◽  
Last Deglaciation ◽  
The Last Deglaciation ◽  
Younger Dryas Event

Timing of the last Deglaciation in the Sierra Nevada of the Mérida Andes, Venezuela

2013 ◽  
Vol 80 (3) ◽  
pp. 482-494 ◽  
Author(s):  
Julien Carcaillet ◽  
Isandra Angel ◽  
Eduardo Carrillo ◽  
Franck A. Audemard ◽  
Christian Beck
Keyword(s):  
Sierra Nevada ◽  
Late Pleistocene ◽  
Younger Dryas ◽  
Ice Cover ◽  
Published Data ◽  
Last Deglaciation ◽  
The Last Deglaciation ◽  
Absolute Age ◽  
Glacial Landforms

In the tropical Mérida Andes (northwestern Venezuela), glacial landforms were found at altitudes between 2600 and 5000 m, corresponding to 600 km2 of ice cover during the maximum glacial extension. However, the lack of sufficient absolute age data prevents detailed reconstruction of the timing of the last deglaciation. On the northwestern flank of the Mucuñuque Massif, successive moraines and striated eroded basement surfaces were sampled for cosmogenic 10Be investigation. Their compilation with published data allows the establishment of a detailed chronology of the post-LGM glacier history. The oldest moraines (18.1 and 16.8 ka) correspond to the Oldest Dryas. Successive moraine ridges indicate stops in the overall retreat between the LGM and the Younger Dryas. The cold and short Older Dryas stadial has been identified. Results indicate that most of the ice withdrew during the Pleistocene. The dataset supports an intensification of the vertical retreat rate from ~ 25 m/ka during the late Pleistocene to ~ 310 m/ka during the Pleistocene/Holocene. Afterwards, the glacier was confined and located in the higher altitude zones. The altitude difference of the Younger Dryas moraines in the Mucubají, La Victoria and Los Zerpa valleys indicates a strong effect of valley orientation on the altitude of moraine development.

scholarly journals A New 14C Calibration Data Set for the Last Deglaciation Based on Marine Varves

Radiocarbon ◽  
1997 ◽  
Vol 40 (1) ◽  
pp. 483-494 ◽  
Author(s):  
Konrad A. Hughen ◽  
Jonathan T. Overpeck ◽  
Scott J. Lehman ◽  
Michaele Kashgarian ◽  
John R. Southon ◽  
...  
Keyword(s):  
Global Climate ◽  
Ice Core ◽  
Younger Dryas ◽  
Core Layer ◽  
Cariaco Basin ◽  
Calibration Data ◽  
Last Deglaciation ◽  
Data Set ◽  
The Last Deglaciation ◽  
Calibration Data Set

Varved sediments of the tropical Cariaco Basin provide a new 14C calibration data set for the period of deglaciation (10,000 to 14,500 years before present: 10–14.5 cal ka bp). Independent evaluations of the Cariaco Basin calendar and 14C chronologies were based on the agreement of varve ages with the GISP2 ice core layer chronology for similar high-resolution paleoclimate records, in addition to 14C age agreement with terrestrial 14C dates, even during large climatic changes. These assessments indicate that the Cariaco Basin 14C reservoir age remained stable throughout the Younger Dryas and late Allerød climatic events and that the varve and 14C chronologies provide an accurate alternative to existing calibrations based on coral U/Th dates. The Cariaco Basin calibration generally agrees with coral-derived calibrations but is more continuous and resolves century-scale details of 14C change not seen in the coral records. 14C plateaus can be identified at 9.6, 11.4, and 11.7 14C ka bp, in addition to a large, sloping “plateau” during the Younger Dryas (∼10 to 11 14C ka bp). Accounting for features such as these is crucial to determining the relative timing and rates of change during abrupt global climate changes of the last deglaciation.

scholarly journals Climate bifurcation during the last deglaciation

2012 ◽  
Vol 8 (1) ◽  
pp. 321-348 ◽  
Author(s):  
T. M. Lenton ◽  
V. N. Livina ◽  
V. Dakos ◽  
M. Scheffer
Keyword(s):  
Climate Variability ◽  
Early Warning ◽  
Bifurcation Point ◽  
Younger Dryas ◽  
Cold Climate ◽  
Meridional Overturning Circulation ◽  
Last Deglaciation ◽  
Overturning Circulation ◽  
Slowing Down ◽  
The Last Deglaciation

Abstract. The last deglaciation was characterised by two abrupt warming events, at the start of the Bølling-Allerød and at the end of the Younger Dryas, but their underlying causes are unclear. Some abrupt climate changes may involve gradual forcing past a bifurcation point, in which a prevailing climate state loses its stability and the climate tips into an alternative state, providing an early warning signal in the form of slowing responses to perturbations. However, the abrupt Dansgaard-Oeschger (DO) events during the last ice age were probably triggered by stochastic fluctuations without bifurcation or early warning, and whether the onset of the Bølling-Allerød (DO event 1) was preceded by slowing down or not is debated. Here we show that the interval from the Last Glacial Maximum to the end of the Younger Dryas, as recorded in three Greenland ice cores with two different climate proxies, was accompanied by a robust slowing down in climate dynamics and an increase in climate variability, consistent with approaching bifurcation. Prior to the Bølling warming there was a robust increase in climate variability but no consistent slowing down signal, suggesting this abrupt change was probably triggered by a stochastic fluctuation. The Bølling warming marked a distinct destabilisation of the climate system, which excited an internal mode of variability in Atlantic meridional overturning circulation strength, causing multi-centennial climate fluctuations. There is some evidence for slowing down in the transition to and during the Younger Dryas. We infer that a bifurcation point was finally approached at the end of the Younger Dryas, in which the cold climate state, with weak Atlantic overturning circulation, lost its stability, and the climate tipped irreversibly into a warm interglacial state. The lack of a large triggering perturbation at the end of the Younger Dryas, and the fact that subsequent meltwater perturbations did not cause sustained cooling, support the bifurcation hypothesis.

Rapid changes in the oceanic fronts in the Norwegian Sea during the last deglaciation: implications for the Younger Dryas cooling event

1998 ◽  
Vol 152 (1-3) ◽  
pp. 177-188 ◽  
Author(s):  
D Klitgaard-Kristensen ◽  
T.L Rasmussen ◽  
H.P Sejrup ◽  
H Haflidason ◽  
Tj.C.E van Weering
Keyword(s):  
Younger Dryas ◽  
Last Deglaciation ◽  
Norwegian Sea ◽  
Oceanic Fronts ◽  
Rapid Changes ◽  
The Last Deglaciation

scholarly journals Human Settlements and the Last Deglaciation in the French Alps

Radiocarbon ◽  
1994 ◽  
Vol 36 (3) ◽  
pp. 345-357 ◽  
Author(s):  
Jacques Evin ◽  
Pierre Bintz ◽  
Guy Monjuvent
Keyword(s):  
Eastern Alps ◽  
Simultaneous Occurrence ◽  
Last Deglaciation ◽  
Glacial Retreat ◽  
French Alps ◽  
Dating Method ◽  
The Last Deglaciation ◽  
Rhone Valley ◽  
Glacial Advance ◽  
The Last Glacial

According to most geological and geomorphological studies, the maximal advance of the Würmian glaciers in the French Alps occurred at least before 40 ka bp and cannot be dated by 14C. Scientists believed that this dating method could be used for dating the last glacial advance and late deglaciation in the region. The scarce and scattered 14C dating results available from geological samples do not confirm an early (ca. 18 or 20 ka bp) age for the total cooling of the ice nor do they prove that residual ice sheets remained at low elevations. Attempting to solve this chronological problem, we compiled current archaeological knowledge of the oldest Late Paleolithic sites. A review of their 14C results shows that no site older than 15 ka bp (with Gravettian, Solutrean or early Magdalenian industries) can be found east of the Saône-Rhône Valley, even at low elevations. Only rare sites, dated to ca. 14.5 ka bp, may be found close to the mountain regions that were suddenly occupied around the beginning of the Bølling period (ca. 13.5 ka bp). Thus, it seems that the eastern Alps offer no evidence for direct association between glacial retreat and human settlement or simultaneous occurrence in early or late deglaciated areas.

scholarly journals Eemian estuarine record forced by glacio-isostasy (southern Iceland)—link with Greenland and deep sea records

2018 ◽  
Vol 55 (2) ◽  
pp. 154-171 ◽  
Author(s):  
Brigitte Van Vliet-Lanoë ◽  
Jean-Luc Schneider ◽  
Águst Guðmundsson ◽  
Hervé Guillou ◽  
Sébastien Nomade ◽  
...  
Keyword(s):  
Ice Core ◽  
Sedimentary Facies ◽  
Last Deglaciation ◽  
Last Interglacial ◽  
Glacial Retreat ◽  
Cold Events ◽  
Loess Deposition ◽  
The Last Deglaciation ◽  
Mis 5E ◽  
Glacial Advance

Central southern Iceland is one of the main outlets of the Icelandic Ice Sheet where a MIS 5e sedimentary complex, the Rangá Formation, is extensively observed below the last deglaciation terminal moraines. Sedimentary facies demonstrate that the Rangá Formation is mostly tidal, up to 215 m (transgression I) and 168 m (transgression II) in altitude. The first highstand reworks a thick tephra from the Grimsvötn volcano, known in marine cores as 5e low/Bas-IV and positioned at ca. 127 Ka BP, the Eemian thermal optimum. This formation is related to a rapid deglaciation followed by two marine transgressions marked by the development of extended mud flats, which were separated by a complex regression phase, associated with loess deposition, ca. 9 Ka in duration. Palaeo jökulhlaups, basaltic flows, and tephra fallouts from the Hekla and Grimsvötn volcanoes affected the sedimentation. The Rangá Formation yields one of the first continuous and complete estuarine records of the Eemian interglacial in Iceland and probably for most of the northern terrestrial Atlantic. This estuarine infill records the distal signature of a complex glacial advance within the last interglacial, already well identified in northern and central Iceland. The glacial advance is attributed to the intra-Eemian cooling events (Greenland GS 26 or marine cold events M-C25-C26). It is followed by a warming and a glacial retreat corresponding to the Greenland GI 25 event. This formation allows, in connection with the timing of recognized volcanic periods, a better insight of the interconnections between sea-level, regional glacial extent, and Northern Hemisphere marine and ice core climatic records.

A Speleothem Record of Younger Dryas Cooling, Klamath Mountains, Oregon, USA

2005 ◽  
Vol 64 (2) ◽  
pp. 249-256 ◽  
Author(s):  
David A. Vacco ◽  
Peter U. Clark ◽  
Alan C. Mix ◽  
Hai Cheng ◽  
R. Lawrence Edwards
Keyword(s):  
Climate Change ◽  
Northern Hemisphere ◽  
Younger Dryas ◽  
Sampling Interval ◽  
Temperature Variability ◽  
Early Holocene ◽  
Last Deglaciation ◽  
Klamath Mountains ◽  
Scale Temperature ◽  
The Last Deglaciation

AbstractA well-dated δ18O record in a stalagmite from a cave in the Klamath Mountains, Oregon, with a sampling interval of 50 yr, indicates that the climate of this region cooled essentially synchronously with Younger Dryas climate change elsewhere in the Northern Hemisphere. The δ18O record also indicates significant century-scale temperature variability during the early Holocene. The δ13C record suggests increasing biomass over the cave through the last deglaciation, with century-scale variability but with little detectable response of vegetation to Younger Dryas cooling.

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