scholarly journals Late glacial to early Holocene development of southern Kattegat

1969 ◽  
Vol 28 ◽  
pp. 21-24 ◽  
Author(s):  
Carina Bendixen ◽  
Jørn Bo Jensen ◽  
Ole Bennike ◽  
Lars Ole Boldreel
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Late Glacial ◽  
Last Deglaciation ◽  
Isostatic Rebound ◽  
North East ◽  
The North ◽  
Tectonically Active ◽  
The Last Deglaciation ◽  
The Øresund Region

The Kattegat region is located in the wrench zone between the Fennoscandian shield and the Danish Basin that has repeatedly been tectonically active. The latest ice advances during the Quaternary in the southern part of Kattegat were from the north-east, east and south-east (Larsen et al. 2009). The last deglaciation took place at c. 18 to 17 ka BP (Lagerlund & Houmark-Nielsen 1993; Houmark-Nielsen et al. 2012) and was followed by inundation of the sea that formed a palaeo-Kattegat (Conradsen 1995) with a sea level that was relatively high because of glacio-isostatic depression. Around 17 ka BP, the ice margin retreated to the Øresund region and meltwater from the retreating ice drained into Kattegat. Over the next millennia, the region was characterised by regression because the isostatic rebound of the crust surpassed the ongoing eustatic sea-level rise, and a regional lowstand followed at the late glacial to Holocene transition (Mörner 1969; Thiede 1987; Lagerlund & Houmark-Nielsen 1993; Jensen et al. 2002a, b).

scholarly journals Cancelation of Deglacial Thermosteric Sea Level Rise by a Barosteric Effect

2020 ◽  
Vol 50 (12) ◽  
pp. 3623-3639
Author(s):  
Geoffrey Gebbie
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Steric Effect ◽  
Three Dimensional ◽  
Steric Effects ◽  
Last Deglaciation ◽  
Effect Analysis ◽  
Height Change ◽  
The Last Deglaciation ◽  
The Last Glacial

AbstractSea level rise over the last deglaciation is dominated by the mass of freshwater added to the oceans by the melting of the great ice sheets. While the steric effect of changing seawater density is secondary over the last 20 000 years, processes connected to deglacial warming, the redistribution of salt, and the pressure load of meltwater all influence sea level rise by more than a meter. Here we develop a diagnostic for steric effects that is valid when oceanic mass is changing. This diagnostic accounts for seawater compression due to the added overlying pressure of glacial meltwater, which is here defined to be a barosteric effect. Analysis of three-dimensional global seawater reconstructions of the last deglaciation indicates that thermosteric height change (1.0–1.5 m) is counteracted by barosteric (−1.9 m) and halosteric (from −0.4 to 0.0 m) effects. The total deglacial steric effect from −0.7 to −1.1 m has the opposite sign of analyses that assume that thermosteric expansion is dominant. Despite the vertical oceanic structure not being well constrained during the Last Glacial Maximum, net seawater contraction appears robust as it occurs in four reconstructions that were produced using different paleoceanographic datasets. Calculations that do not account for changes in ocean pressure give the misleading impression that steric effects enhanced deglacial sea level rise.

scholarly journals GEOCENTRIC MEAN SEA LEVEL FIELDS AT THE GERMAN NORTH SEA AND BALTIC COAST

2018 ◽  
pp. 21
Author(s):  
Jessica Kelln ◽  
Sönke Dangendorf ◽  
Jürgen Jensen ◽  
Justus Patzke ◽  
Wolfgang Niemeier ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Tide Gauge ◽  
Last Deglaciation ◽  
Mean Sea Level ◽  
Baltic Coast ◽  
Vertical Land Motion ◽  
Level Information ◽  
The Last Deglaciation ◽  
Global Mean Sea Level

Global mean sea level has risen over the 20th century (Hay et al. 2015; Dangendorf et al. 2017) and under sustained greenhouse gas emissions it is projected to further accelerate throughout the 21st century (Church et al. 2013) with large spatial variations, significantly threatening coastal communities. Locally the effects of geocentric (sometimes also referred to absolute) sea level rise can further be amplified by vertical land motion (VLM) due to natural adjustments of the solid earth to the melting of the large ice-sheets during the last deglaciation (GIA) or local anthropogenic interventions such as groundwater or gas withdrawal (e.g. Santamaría-Gómez et al. 2017). Both, the observed and projected geocentric sea level rise as well as VLM are critically important for coastal planning and engineering, since only their combined effect determines the total threat of coastal flooding at specific locations. Furthermore, due large spatial variability of sea level, information is required not only at isolated tide gauge (TG) locations but also along the coastline stretches in between.

scholarly journals An Ancient Meltwater Pulse Raised Sea Levels by 18 Meters

Eos ◽  
2021 ◽  
Vol 102 ◽  
Author(s):  
Tim Hornyak
Keyword(s):  
North America ◽  
Sea Level Rise ◽  
Sea Level ◽  
Last Deglaciation ◽  
Sea Levels ◽  
The Last Deglaciation ◽  
New Research

Meltwater pulse 1A, a period of rapid sea level rise after the last deglaciation, was powered by melting ice from North America and Scandinavia, according to new research.

Reassessing global ice volume: uncertainty and structure in sea level records

2021 ◽  
Author(s):  
Fiona D. Hibbert ◽  
Felicity Williams ◽  
Eelco Rohling
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Full Range ◽  
Ice Sheets ◽  
Change Point Analysis ◽  
Last Deglaciation ◽  
Ice Volume ◽  
Global Ice Volume ◽  
Modern Analogue ◽  
The Last Deglaciation

<p>Geologically recorded sea-level variations represent the sum total of all contributing processes, be it known or unknown, and may thus help in finding the full range of future sea-level rise. Significant sea-level-rise contributions from both northern and southern ice sheets are not unprecedented in the geological record and offer a well-constrained range of natural scenarios from intervals during which ice volumes were similar to or smaller than present (i.e., interglacial periods), to intervals during which total ice volume was greater (i.e., glacial periods).</p><p>The last deglaciation is the most recent period of widespread destabilisation and collapse of major continental ice sheets. Records spanning the last deglaciation (as well as the ice volume maxima) are few, fragmentary and seemingly inconsistent (e.g., the timing and magnitude of melt-water pulses), in part due to locational (tectonic and glacio-isostatic) as well as modern analogue considerations (e.g., palaeo-water depth or facies formation depth). We present a new synthesis of sea-level indicators, with particular emphasis on the geological and biological context, as well as the uncertainties of each record. Using this new compilation and the novel application of statistical methods (trans-dimensional change-point analysis, which avoids “overfitting” of noise in the data), we will assess global ice-volume changes, sea-level fluctuations and changes in climate during the last deglaciation. Finally, we discuss the implications of these uncertainties on our ability to constrain past cryosphere changes.</p>

Glacial isostatic adjustment near the center of the former Patagonian Ice Sheet (48°S) during the last 16.5 kyr

2021 ◽  
Author(s):  
Matthias Troch ◽  
Sebastien Bertrand ◽  
Carina B. Lange ◽  
Paola Cardenas ◽  
Helge Arz ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Average Rate ◽  
Ice Sheet ◽  
Late Glacial ◽  
Glacial Isostatic Adjustment ◽  
Isostatic Rebound ◽  
Isostatic Adjustment ◽  
Modelling Studies ◽  
Global Sea Level

<p>Our understanding of glacial isostatic rebound across Patagonia is highly limited, despite its importance to constrain past ice volume estimates and better comprehend relative sea-level variations. With this in mind, our research objective is to reconstruct the magnitude and rate of Late Glacial to Holocene glacial isostatic adjustment near the center of the former Patagonian Ice Sheet. We focus on Larenas Bay (48°S; 1.26 km<sup>2</sup>), which is connected to Baker Channel through a shallow (<em>ca.</em> 7.4 m) and narrow (<em>ca.</em> 150 m across) inlet, and hence has the potential to record periods of basin isolation and marine ingression. The paleoenvironmental evolution of the bay was investigated through a sedimentological analysis of a 9.2 m long, radiocarbon-dated, sediment core covering the last 16.8 cal. kyr BP. Salinity indicators, including diatom paleoecology, alkenone concentrations and CaCO<sub>3</sub> content, were used to reconstruct the bay’s connectivity to the fjord. Results indicate that Larenas Bay was a marine environment before 16.5 cal. kyr BP and after 9.1 cal. kyr BP, but that it was disconnected from Baker Channel in-between. We infer that glacial isostatic adjustment outpaced global sea-level rise between 16.5 – 9.1 cal. kyr BP. During the Late Glacial - Holocene transition, the center of the former Patagonian Ice Sheet rose <em>ca.</em> 96 m, at an average rate of 1.30 cm/year. During the remainder of the Holocene, glacial isostatic adjustment continued (<em>ca.</em> 19.5 m), but at a slower average pace of 0.21 cm/year. Comparisons between multi-centennial variations in the salinity indicators and existing records of global sea-level rise suggest that the glacial isostatic adjustment rate fluctuated during these time intervals, in agreement with local glacier dynamics. More specifically, most of the glacial isostatic adjustment registered between 16.5 – 9.1 cal. kyr BP seems to have occurred before meltwater pulse 1A (14.5 – 14.0 kyr BP). Likewise, it appears that the highest Holocene glacial isostatic rebound rates occurred during the last 1.4 kyr, most likely in response to glacier recession from Neoglacial maxima. This implies a relatively rapid response of the local solid earth to ice unloading, which agrees with independent modelling studies investigating contemporary uplift. We conclude that the center of the former Patagonian Ice Sheet experienced a glacial isostatic adjustment of <em>ca.</em> 115 m over the last 16.5 kyr, and that >80% occurred during the Late Glacial and early Holocene.</p>

Sea-Level Estimates during the Last Deglaciation Based on δ18O and Accelerator Mass Spectrometry 14C Ages Measured in Globigerina bulloides

1989 ◽  
Vol 31 (3) ◽  
pp. 381-391 ◽  
Author(s):  
Edouard Bard ◽  
Richard Fairbanks ◽  
Maurice Arnold ◽  
Pierre Maurice ◽  
Josette Duprat ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Sea Level ◽  
North Atlantic ◽  
Accelerator Mass Spectrometry ◽  
Planktonic Foraminifera ◽  
Last Deglaciation ◽  
Ice Melt ◽  
Globigerina Bulloides ◽  
The North ◽  
The Last Deglaciation

AbstractCoupled measurements of δ18O and accelerator mass spectrometry (AMS) 14C in a particular species of planktonic foraminifera may be used to calculate sea-level estimates for the last deglaciation. Of critical importance for this type of study is a knowledge of the seasonality of foraminiferal growth, which can be provided by δ18O measurements of modern shells (core tops, plankton tows). Isotopic (δ18O, AMS-14C dating) and faunal records (transfer function sea surface temperature) were obtained from two cores in the North Atlantic at about 37°N. The locations were chosen to obtain high sedimentation rate records removed from the major ice-melt discharge areas of the last deglaciation. Based upon Globigerina bulloides data, four δ18O-based sea-level estimates were calculated: −67 ± 7 m at 12,200 yr B.P. and −24 ± 8 m at about 8200 yr B.P. for core SU 81-18; −83 ± 10 m at 12,200 yr B.P. and −13 ± 11 m at about 8500 yr B.P. for core SU 81-14. Using a second working hypothesis concerning the seasonability of G. bulloides growth, it is suggested that the sea-level rose by about 40 m during the millennium which followed 14,500 yr B.P.

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