A new late-glacial sea-level record for St. George's Bay, Newfoundland

A new relative sea-level curve is presented for St. George's Bay, southwest Newfoundland, based on (i) a revised stratigraphic framework and depositional model for glacial and marine deposits exposed in coastal sections and (ii) 19 new radiocarbon dates on shells from emerged and submerged marine deposits, including fossiliferous diamictons. The data produce a type B sea-level curve, falling steeply from an extrapolated marine limit of 105 m above sea level at 14.0 14C ka BP, passing below modern sea level at ~10.6 14C ka BP, to a lowstand of 25 m at ~9.4 14C ka BP, and rising again close to modern sea level by 5.0 14C ka BP. Marine limits in the northern part of the bay have lower elevations (2765 m) due to delayed ice retreat of up to 1.2 ka. Between 12.8 and at least 12.3 14C ka BP, glaciofluvial outwash graded to falling sea levels between 27 and 17 m above present throughout the bay, whereas lowstand deltas were constructed in sheltered locations at the outlets of major river systems, when sea level was 25 m below present. Establishment of the sea-level lowstand at ~9.4 14C ka BP is supported by new seismic data and radiocarbon dates from St. George's Bay and also from White Bear Bay on the south coast of Newfoundland. Short-term fluctuations in emergence rates of 12 m/century between 12.5 and 9.5 14C ka BP are attributed to variable eustatic sea-level rise, superimposed on a declining local glacio-isostatic adjustment.

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Late Quaternary glacial and sea-level events, Clements Markham Inlet, northern Ellesmere Island, Arctic Canada

Canadian Journal of Earth Sciences ◽

10.1139/e86-129 ◽

1986 ◽

Vol 23 (9) ◽

pp. 1343-1355 ◽

Cited By ~ 33

Author(s):

Jan Bednarski

Keyword(s):

Sea Level ◽

Late Quaternary ◽

Ellesmere Island ◽

Glacial Retreat ◽

Radiocarbon Dates ◽

Ice Caps ◽

Marine Deposits ◽

Ice Retreat ◽

Level Ice ◽

Small Valley

Clements Markham Inlet cuts into the Grant Land Mountains of the northernmost coast of Ellesmere Island. The head of the inlet is bounded on three sides by mountain ice caps that surround lowlands mantled by extensive raised marine deposits. Fieldwork and mapping of late Quaternary sediments were used to determine the limits of past glaciations and the nature of ice retreat from the inlet head. Forty-five radiocarbon dates on driftwood and marine shells provide a deglacial chronology and document related sea-level adjustments.High-level ice-marginal meltwater channels and mountain summit erratics indicate that ice once inundated all of Clements Markham Inlet. During at least one of these undated glaciations, ice flowed unconstrained by the local topography. In contrast, the most recent glaciation involved confluent trunk glaciers, which terminated near the head of the inlet. Beyond this terminus, smaller glaciers entering the sides of the inlet debouched into a glacioisostatically depressed sea (full glacial sea). Retreat from the last glaciation is documented by moraines, kame terraces, and ice-contact deltas.Inside the ice limit at the head of the inlet, sections commonly show that a marine transgression occurred immediately after the retreat of the ice. Conversely, sections outside the last ice limit, along the sides of the inlet, show complex intercalations of marine and glacigenic sediments. These indicate proximal ice-front conditions where small valley glaciers locally contacted the sea.The oldest date on the last ice limit is 9845 BP. After this, slow retreat was in progress, and some glaciers were within 6 km of their current positions by ca. 9700 BP. At the head of the inlet, the mouths of the confluent valleys became ice free by 8000 BP. After 8000 BP, glacial retreat accelerated greatly, so that the entire lowland became ice free within 400 years.Relative sea-level curves from the inlet indicate ice-load changes that confirm this pattern of ice retreat. Outside the last ice limit, the full glacial sea reached 124 m asl by at least 10 000 BP. Emergence from this sea occurred slowly between at least 10 000 and 8000 BP (0.72 m 100 year−1). This period was followed by "normal" rapid postglacial emergence, which decelerated to the present.The marine limit of the full glacial sea rises from 92 m asl, at the outer coast, to 124 m asl near the last ice limit at the head of the inlet. Initial emergence from the full glacial sea occurred simultaneously throughout the inlet. On the proximal side of the last ice limit, the marine limit descends in the up-ice direction and becomes progressively younger. Individual strandlines tilt up in a southwesterly direction towards the central Grant Land Mountains, suggesting a former centre of glacio-isostatic loading in that area.

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Radiocarbon age of Robinson's Head moraine, west Newfoundland, and its significance for postglacial sea level changes

Canadian Journal of Earth Sciences ◽

10.1139/e77-179 ◽

1977 ◽

Vol 14 (9) ◽

pp. 2121-2126 ◽

Cited By ~ 19

Author(s):

Ian A. Brookes

Keyword(s):

Sea Level ◽

Late Glacial ◽

Radiocarbon Date ◽

Level Curve ◽

Sea Level Changes ◽

Radiocarbon Dates ◽

Radiocarbon Age ◽

Isostatic Uplift ◽

First Approximation

A radiocarbon date of 12 600 ± 140 years BP (GSC-2295) is reported on marine shells from sands within the Robinson's Head kame moraine at Stephen ville, Newfoundland. The moraine was deposited simultaneously with a delta-kame distal to it during a brief interval of increased ice marginal activity. This is marked at Stephenville by a temporary halt in landward marginal recession, but in some other localities around St. George's Bay by a lobate readvance into the late-glacial sea. The date refers to the time of moraine and delta-kame construction and confirms an earlier estimation. Other radiocarbon dates from the area, relating more or less closely to past sea level positions at Robinson's, south of Stephenville, are used, with an hypothetical isostatic uplift curve and a published eustatic sea level curve, to produce a first approximation to postglacial changes of local sea level in the St. George's Bay region.

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Moscow MV Lomonosov State University Radiocarbon Dates II: Sea Level Indicators from Coastal USSR

Radiocarbon ◽

10.1017/s0033822200006275 ◽

1983 ◽

Vol 25 (3) ◽

pp. 892-898 ◽

Cited By ~ 1

Author(s):

N I Glushankova ◽

O B Parunin ◽

A O Selivanov ◽

A I Shlukov ◽

T A Timashkova

Keyword(s):

Soviet Union ◽

Sea Level ◽

State University ◽

Radiocarbon Dates ◽

Sea Levels ◽

The Soviet Union ◽

Laboratory Results ◽

Last Deglacial

The following list summarizes the post-1970 laboratory results of 14C dating of ancient sea-level indicators from the coasts of the Soviet Union. One of the aims of the International Geologic Correlation Programme Project No. 61 “Sea level movements during the last deglacial hemicycle” is the global cataloguing and mapping of ancient sea levels. The laboratory, which acts as the USSR National curator for these age measurements obtains dates sampled from its own expeditions and from other institutions of the country.

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Past Sea Levels, Eustasy and Deformation of the Earth

Quaternary Research ◽

10.1016/0033-5894(72)90001-4 ◽

1972 ◽

Vol 2 (1) ◽

pp. 1-14 ◽

Cited By ~ 153

Author(s):

R. I. Walcott

Keyword(s):

Sea Level ◽

Late Glacial ◽

The United States ◽

Ground Subsidence ◽

Postglacial Rebound ◽

Vertical Movements ◽

Sea Levels ◽

Atlantic Seaboard ◽

The Earth ◽

Change In Mean

Vertical movements of the earth's surface related to postglacial rebound, the eustatic rise in sea level and the elastic deformation of the globe due to melting of late glacial ice sheets are calculated for simplified models of the earth. The movements of the ground are large and require a reevaluation of what is meant by eustatic sea level change. This is defined here as an ocean-wide average change in mean sea level and its measurement requires widely distributed observations weighted according to the areas of oceans they represent. Evidence of a postglacial (6000-0 years BP) relative rise in sea level comes largely from regions affected by ground subsidence related to adjacent upward postglacial rebound movements in deglaciated areas: evidence for a relative fall of sea level comes from coastlines well removed from areas of rebound and which have been affected by a rise of the continental areas through compensation for the eustatic load. It is concluded: (1) no substantial eustatic change of sea level in the past 6,000 years is required to explain postglacial sea levels: (2) in late glacial time the eustatic curve is probably more like the sea level curve of Texas and Mexico than that of the Atlantic seaboard of the United States: (3) that the information of past sea levels, when sufficiently widespread, can provide an important method of studying the deep mechanical structure of the earth.

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Relative sea-level changes in crete: reassessment of radiocarbon dates from Sphakia and west Crete

The Annual of the British School at Athens ◽

10.1017/s0068245400017378 ◽

2002 ◽

Vol 97 ◽

pp. 171-200 ◽

Cited By ~ 11

Author(s):

Simon Price ◽

Tom Higham ◽

Lucia Nixon ◽

Jennifer Moody

Keyword(s):

Sea Level ◽

Late Antiquity ◽

Isotopic Fractionation ◽

Sea Level Changes ◽

Relative Sea Level ◽

Radiocarbon Dates ◽

Sea Levels ◽

Catastrophic Earthquake ◽

Radiocarbon Data ◽

Calendar Dates

This article is concerned with the recognition and dating of Holocene relative sea-level changes along the coast of west Crete (an island located in the active Hellenic subduction arc of the southern Aegean) and in particular in Sphakia. Radiocarbon data for changes in sea levels collected and analysed previously must (a) be recorrected to take into account isotopic fractionation, and (b) recalibrated by using the new marine reservoir value. These new radiocarbon dates are analysed using Bayesian statistics. The resulting calendar dates for changes in sea level are younger than previously assumed. In particular the Great Uplift in western Crete in late antiquity must be dated to the fifth or sixth century AD, not to AD 365. Moreover, recent work on tectonics suggests that the Great Uplift need not have been accompanied by a catastrophic earthquake. Finally, we consider the consequences of the Great Uplift for some coastal sites in Sphakia.

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Submerged speleothem in Malta indicates tectonic stability throughout the Holocene

The Holocene ◽

10.1177/0959683618782613 ◽

2018 ◽

Vol 28 (10) ◽

pp. 1588-1597 ◽

Cited By ~ 1

Author(s):

Stefano Furlani ◽

Fabrizio Antonioli ◽

Timmy Gambin ◽

Sara Biolchi ◽

Saviour Formosa ◽

...

Keyword(s):

Sea Level ◽

Sea Level Changes ◽

Radiocarbon Dates ◽

The Holocene ◽

Karst Environment ◽

Marine Deposits ◽

Archaeological Data ◽

Decadal Scale ◽

Term Data

Submerged caves represent potential archives of speleothems with continental and marine biogenic layers. In turn, these can be used to reconstruct relative sea-level changes. This study presents new data on the tectonic behaviour of the island of Malta during the Holocene. These data were obtained from a speleothem sampled, during an underwater survey, at a depth of −14.5 m, inside a recently discovered submerged cave. Since the cave was mainly formed in a subaerial karst environment, the presence of a speleothem with serpulids growing on its continental layers permitted the reconstruction of the chronology for drowning of the cave. The radiocarbon dates obtained from the penultimate and last continental layers of the speleothem, before a serpulid encrustation, were compared with synthetic aperture radar (SAR) and global positioning system (GPS) data, together with published sedimentological and archaeological data. The radiocarbon analyses provided an average age of 7.6 ka BP that perfectly aligns with the Lambeck’s model of Holocene sea level. Morevoer, long-term data agree with published archeological and sedimentological data as well as with SAR interpherometric and GPS trends on a decadal scale. We conclude that the Maltese islands were tectonically stable during the Holocene, and this tectonic behaviour still persists nowadays. On the contrary, new informations on older deposits, such as MIS5e (Maritime Isotope Stage, corresponding to 125 ka ago) were not found in the study area, confirming the lack of older Quaternary marine deposits in these islands.

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Holocene relative sea-level data for the East Frisian barrier coast, NW Germany, southern North Sea

Netherlands Journal of Geosciences – Geologie en Mijnbouw ◽

10.1017/njg.2021.11 ◽

2021 ◽

Vol 100 ◽

Cited By ~ 1

Author(s):

Friederike Bungenstock ◽

Holger Freund ◽

Alexander Bartholomä

Keyword(s):

Sea Level ◽

North Sea ◽

Level Curve ◽

Relative Sea Level ◽

Southern North Sea ◽

Isostatic Adjustment ◽

Landscape Reconstruction ◽

Time Period ◽

Level Data ◽

Age Constraints

Abstract Collecting sea-level data from restricted coastal areas is essential for understanding local effects on relative sea level. Here, a revised relative mean sea-level curve for the area of the East Frisian island Langeoog, northwestern Germany, for the time period from 7200 cal BP until Recent is presented. The revision is based on the reinterpretation of previously published and unpublished data following the HOLSEA standardisation of data handling. Altogether 68 sea-level data taken from 32 cores and outcrops from Langeoog, its back-barrier and the adjacent mainland, which have been collected since the 1950s for mapping and landscape reconstruction purposes, are presented. The age constraints, derived from radiocarbon ages of basal peat, intercalated peat and molluscs and optical dating of tidal deposits, were evaluated in terms of the HOLSEA sea-level protocol and their stratigraphic context. For 7200 cal BP until modern times, 30 sea-level index points with different uncertainty ranges were defined. Additionally, a factor of decompaction was estimated for the remaining basal peat samples as well as for the underlying sediments of intercalated peat samples. The comparison of the Langeoog relative sea-level curve with the relative sea-level curve from the western Netherlands shows that the Langeoog curve lies up to 0.80 m lower than the Dutch curve and diverges for the time before 6000 cal BP. Though the offset coincides with the overall predicted trend of glacial-isostatic adjustment, it is less than predicted. Our study provides a useful assessment of legacy data and contributes to an improved sea-level index dataset for the southern North Sea coast.

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Nass River on the move: radar facies analysis of glaciofluvial sedimentation and its response to sea-level change in northwestern British Columbia

Canadian Journal of Earth Sciences ◽

10.1139/e06-073 ◽

2006 ◽

Vol 43 (11) ◽

pp. 1733-1746 ◽

Cited By ~ 2

Author(s):

S J McCuaig ◽

M C Roberts

Keyword(s):

British Columbia ◽

Sea Level ◽

Facies Analysis ◽

Late Glacial ◽

Depositional Environments ◽

Coarse Grained ◽

Sea Levels ◽

Stratal Architecture ◽

Forced Regression ◽

Radar Facies

The Nass Valley of northwestern British Columbia is a glacial fiord containing extensive glaciomarine and glaciofluvial sediments. Two parallel braidplains, separated by a bedrock ridge, were deposited within the fiord. Mapping of these deposits led to the hypothesis that the braidplains must have terminated at deltas. However, a lack of surface exposures meant that ground-penetrating radar was needed to investigate these deposits. Radar facies analysis aided in the identification of braidplain, braid delta and glaciomarine depositional environments, as well as underlying bedrock. Several deltas graded to different sea levels were discovered, allowing inferences to be made about the relationship of falling sea level to sediment architecture. The upper section of the western braidplain is graded to a sea level of 185 m above sea level (asl), indicating that the proto-Nass River flowed on the western side of the bedrock ridge when the sea was at that level. However, the river moved to the east side of the ridge as sea level fell, depositing the extensive Aiyansh Braidplain – Braid Delta, which is graded to a 152 m sea-level stand. Several other deltas also formed at this sea-level stand. Avulsion occurred and the river flowed on the west side of the ridge again when sea level fell to 134 m asl. The river remained in this position throughout late glacial time and eventually evolved into the modern Nass River. The coarse-grained deposits are indicative of forced regression, with both stepped-top attached and detached stratal architecture present.

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Contraction-expansion dynamics of reef species in response to sea-level changes

10.1101/2021.01.06.425656 ◽

2021 ◽

Author(s):

Thierry B Hoareau ◽

Petrus Pretorius

Keyword(s):

Sea Level ◽

Subsequent Development ◽

Population Level ◽

Marine Species ◽

Late Glacial ◽

Sea Level Changes ◽

Radiocarbon Dates ◽

Last Glacial ◽

Sea Level Fluctuations ◽

The Last Glacial

The contraction-expansion model (CEM) describes the dynamics of species that survived in refugia during the last glacial maximum (LGM) and expanded their range when environmental conditions slowly improved from the Late Glacial through to the Holocene. The CEM has been proposed to describe the dynamics of reef species in response to sea-level fluctuations from a range of disciplines, but genetic inferences rather suggest stable population sizes since the last glacial period. Here, we address this paradox by providing a new model of modern reef development, by assessing the effect of LGM bottlenecks using genetic simulations, and by using a survey of the literature on reef species to compile both estimates of times to expansion and applied rates of molecular evolution. Using previously published radiocarbon dates of core data, we propose a synthetic model for the dynamics of modern coral reefs in the Indo-Pacific region. This model describes both an initiation at 9.9 ka and subsequent development that confirms a strong influence of sea-level fluctuations on reef dynamics. Simulations based on mtDNA datasets showed that pre-LGM genetic signatures of expansion are lost. Recent literature shows that, although genetic expansions of tropical marine species are frequent (>95%), the onset of these expansions is old (median ~110 ka), which indicates that most populations have remained stable since before the LGM. These pre-LGM expansions are explained by the low mutation rates (1.66% changes/site/Myr) known to be inadequate to calibrate time at population level. Specific calibrations should help solve the paradox and generalise the CEM for reef species.

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

10.5194/egusphere-egu21-6185 ◽

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

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&#176;S; 1.26 km2), which is connected to Baker Channel through a shallow (ca. 7.4 m) and narrow (ca. 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 CaCO3 content, were used to reconstruct the bay&#8217;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 &#8211; 9.1 cal. kyr BP. During the Late Glacial - Holocene transition, the center of the former Patagonian Ice Sheet rose ca. 96 m, at an average rate of 1.30 cm/year. During the remainder of the Holocene, glacial isostatic adjustment continued (ca. 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 &#8211; 9.1 cal. kyr BP seems to have occurred before meltwater pulse 1A (14.5 &#8211; 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 ca. 115 m over the last 16.5 kyr, and that >80% occurred during the Late Glacial and early Holocene.

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