New relative sea-level curves for the southern Scott Coast, Antarctica: evidence for Holocene deglaciation of the western Ross Sea

1999 ◽  
Vol 14 (7) ◽  
pp. 641-650 ◽  
Author(s):  
Brenda L. Hall ◽  
George H. Denton
Keyword(s):  
Sea Level ◽  
Ross Sea ◽  
Relative Sea Level ◽  
Level Curves ◽  
Western Ross Sea

Mid-Cretaceous onlap history of the Market Weighton structural high, northeast England

1999 ◽  
Vol 136 (6) ◽  
pp. 681-696 ◽  
Author(s):  
C. J. UNDERWOOD ◽  
S. F. MITCHELL
Keyword(s):  
Sea Level ◽  
High Frequency ◽  
Sedimentary Facies ◽  
Relative Sea Level ◽  
Western Margin ◽  
Level Curves ◽  
History Of ◽  
Tectonic Settings ◽  
Global Sea Level ◽  
Structural High

The mid-Cretaceous sediments of northeast England were deposited at the western margin of the southern North Sea Basin, with sedimentation occurring in a range of tectonic settings. Detailed analysis of the areal distribution and sedimentary facies of Aptian to earliest Cenomanian sediments has allowed the pattern of onlap onto the Market Weighton structural high and changes in relative sea level to be documented. Successive onlap episodes during the Early Aptian, Late Aptian and Early Albian culminated in the final flooding of the structure during the Late Albian (varicosum Subzone). Sea-level curves generated from coastal onlap patterns are difficult to relate to published ‘global’ sea-level curves due to the high frequency of the fluctuations in relative sea level observed. Despite this, detailed correlation and analysis of sedimentological events suggest that even the most expanded, basinal succession is relatively incomplete. This study has also shown that the change from dominantly syn-tectonic to dominantly post-tectonic sedimentation style occurred in the late Early Albian.

A comparison of observed and theoretical postglacial relative sea level in Atlantic Canada

1981 ◽  
Vol 18 (7) ◽  
pp. 1146-1163 ◽  
Author(s):  
Garry Quinlan ◽  
Christopher Beaumont
Keyword(s):  
Sea Level ◽  
Field Data ◽  
Sea Level Change ◽  
Atlantic Canada ◽  
Relative Sea Level ◽  
Level Curves ◽  
Level Change ◽  
The Common ◽  
Late Wisconsinan ◽  
Outermost Zone

Two extreme models of late Wisconsinan ice cover in Atlantic Canada and the northeastern U.S.A. are shown to produce postglacial relative sea level curves that bracket existing field observations at six sites throughout the region. This suggests that the true late Wisconsinan ice distribution is probably intermediate to the two contrasting reconstructions proposed. Both ice models predict the existence of four relative sea level zones: an innermost zone closest to the centre of glaciation in which relative sea level falls continuously throughout postglacial time; an outermost zone in which it rises continuously; and two transitional zones in which it first falls and then rises in varying proportions according to the distance from the ice margin. The distinctive forms of the relative sea level curves are probably representative of each of the zones and are unlikely to be significantly perturbed even by large local ice readvances. They, therefore, establish patterns with which future field data are expected to conform. The form that the geological record of relative sea level change is likely to take within each zone is discussed and promising settings for the collection of new data are proposed. The common practice of separating relative sea level into an isostatic and a eustatic component is analysed and shown to be incorrect as usually applied. The practice is also shown to be unnecessary because the models discussed in this paper predict changes in relative sea level that can be compared directly with the observations.

Late Deglaciation of the Central Labrador Coast and Its Implications for the Age of Glacial Lakes Naskaupi and McLean and for Prehistory

1990 ◽  
Vol 34 (3) ◽  
pp. 296-305 ◽  
Author(s):  
Peter U. Clark ◽  
William W. Fitzhugh
Keyword(s):  
Sea Level ◽  
Ice Sheet ◽  
Late Glacial ◽  
Time Frame ◽  
Laurentide Ice Sheet ◽  
Glacial Lakes ◽  
Central Coast ◽  
Relative Sea Level ◽  
Level Curves

AbstractThe age of the marine limit and associated deglaciation has been estimated from relative sea-level curves for the Hopedale and Nain areas of the central Labrador coast as approximately 7600 ± 200 and 8500 ± 200 yr ago, respectively. These ages indicate that the ice margin remained on the coast for up to 3000 yr longer than previously estimated. Because the central coast is due east of glacial lakes Naskaupi and McLean, the earliest the lakes could have formed was <8500 ± 200 yr ago, with their largest phases being fully established only after 7600 ± 200 yr ago. This suggests that the age of the lakes, and associated deglaciation of the central Labrador-Ungava region, is younger by at least 1500 yr than previously estimated. A late-glacial marine-based ice mass in Ungava Bay that dammed the lakes collapsed ca. 7000 yr ago. Within this time frame, therefore, the glacial lakes only existed for <500 yr. The persistence of the Laurentide Ice Sheet margin on the central Labrador coast until 7600 yr ago probably restricted the northward movement of early prehistoric people into northern Labrador.

North American Deglacial Marine- and Lake-Limit Surfaces*

2007 ◽  
Vol 59 (2-3) ◽  
pp. 155-185 ◽  
Author(s):  
Arthur S. Dyke ◽  
Lynda A. Dredge ◽  
Douglas A. Hodgson
Keyword(s):  
North America ◽  
Sea Level Rise ◽  
Sea Level ◽  
North American ◽  
Ice Sheet ◽  
Glacial Lake ◽  
Limit Surface ◽  
Relative Sea Level ◽  
Level Curves ◽  
Recent Synthesis

Abstract The deglacial marine-limit surface is a virtual topography that shows the increase of elevation since deglaciation. The currently available set of marine-limit elevations (n = 929), about three times the number available in the most recent synthesis, allows a fairly detailed rendering of the surface across most of glaciated North America and Greenland. Certain large glacial lake-limit surfaces are analogous to marine-limit surfaces, except that their gradients were not dampened by eustatic sea-level rise. Collectively the surfaces reflect both gross ice-sheet geometry and regional to local rates of ice-marginal recession. As such, they are replication targets for glacioisostatic modelling that are supplementary to and more continuously distributed than relative sea-level curves.

Isostatic adjustments in a full glacial sea

1983 ◽  
Vol 20 (6) ◽  
pp. 895-917 ◽  
Author(s):  
John England
Keyword(s):  
Sea Level ◽  
Ellesmere Island ◽  
Relative Sea Level ◽  
Level Curves ◽  
Last Glaciation ◽  
Isostatic Equilibrium ◽  
Paleoclimatic Changes ◽  
History Of ◽  
Rapid Emergence

During the last glaciation an ice-free corridor existed between the northeast Ellesmere Island and northwest Greenland ice sheets. This corridor constituted a peripheral depression in which the marine limit marks the uppermost extent of a full glacial sea. The full glacial sea is characterized by (1) 14C dates on in situ marine shells that predate initial emergence (unloading) followed by (2) synchronous emergence from the marine limit throughout the peripheral depression. Relative sea-level curves from the full glacial sea confirm previous morphostratigraphic and glacioisostatic evidence for limited ice extent during the last glaciation. These curves also document the history of glacial unloading and the form of the relative sea-level curve that one would theoretically expect in the peripheral depression. The form of the curves presented here is unlike any other published emergence curves from arctic Canada or from Fennoscandia.The relative sea-level curves for northeast Ellesmere Island show three segments: (1) an interval of stable relative sea level (isostatic equilibrium) at the marine limit between at least 11 000 and 8000 BP; (2) an interval of slow emergence from 8000 to 6200 BP during which northeast Ellesmere Island ice slowly retreated; and (3) an interval of rapid emergence, caused by rapid glacial unloading, after 6200 BP when a prominent amelioration was in progress. These relative sea-level curves are discussed in relation to other paleoclimatic changes and the deglacial history of northwest Greenland. These curves are of regional importance in that they provide a new means of distinguishing between areas that were ice covered and ice free during the last glaciation.

Holocene delevelling of Devon Island, Arctic Canada: implications for ice sheet geometry and crustal response

1998 ◽  
Vol 35 (8) ◽  
pp. 885-904 ◽  
Author(s):  
Arthur S Dyke
Keyword(s):  
Sea Level ◽  
Ice Sheet ◽  
Bowhead Whale ◽  
Large Set ◽  
Relative Sea Level ◽  
Radiocarbon Dates ◽  
Level Curves ◽  
Devon Island ◽  
Ice Load ◽  
Raised Beaches

The raised beaches and deltas of Devon Island contain an abundance of dateable materials. A large set of radiocarbon dates (228), 154 of which are new, are used to construct relative sea level curves and isobase maps for the island. The best materials for this purpose are driftwood logs (61 dates) and bowhead whale bones (74 dates) from raised beaches and mollusc shells from marine-limit deltas (20 dates) or from altitudes close to marine limit (14 dates). During the last glacial maximum, the island is thought to have lain beneath the southeastern flank of the Innuitian Ice Sheet. The relative sea level history is congruent with that inferred ice configuration. The island spans half the ice sheet width. Relative sea level curves are of simple exponential form, except near the glacial limit where an early Holocene emergence proceeded to a middle Holocene lowstand below present sea level, which was followed by submergence attending the passage of the crustal forebulge. The response times of relative sea level curves and of crustal uplift decrease from the uplift centre toward the limit of loading, but the change appears strongest near the limit. The Innuitian uplift is separated from the Laurentide uplift to the south by a strong isobase embayment over Lancaster Sound. Hence, ice load irregularities with wavelengths of about 100 km were large enough to leave an isostatic thumbprint in this region of the continent. The apparent absence of a similar embayment over Jones Sound probably indicates a greater Late Wisconsinan ice load there, or a thicker crust than in Lancaster Sound.

The aulacopleurid trilobiteMaurotarionAlberti, 1969, in the Silurian-Devonian of Argentina: systematic, phylogenetic and paleobiogeographic significance

2010 ◽  
Vol 84 (6) ◽  
pp. 1082-1098 ◽  
Author(s):  
Juan J. Rustán ◽  
N. Emilio Vaccari
Keyword(s):  
South Africa ◽  
New Species ◽  
Sea Level ◽  
South African ◽  
Lower Devonian ◽  
Relative Sea Level ◽  
African Species ◽  
Level Curves ◽  
New Subgenus ◽  
The Family

Five new species ofMaurotarionAlberti, 1969 from the Silurian Lipeón Formation and Lower Devonian Talacasto Formation of Argentina are recognized. The comparisons with Bolivian and South African species support a Malvinokaffric clade based on librigenal synapomorphies, here erected asMaurotarion(Malvinotarion) new subgenus. The Malvinokaffric origin of the family would not be a migration from lower paleolatitudes but an Early Silurian stock of rare cosmopolitan ancestors which underwent a great Devonian radiation. Two lineages can be recognized within MalvinokaffricMaurotarion.The Silurian-Pragiandereimsilineage is a plesiomorphic one resembling Silurian representatives and involvesM.(Malvinotarion)dereimsi, M.(Malvinotarion)talacastoensenew species,M.(Malvinotarion?) new species A,M.(Malvinotarion?) new species B,M.(Malvinotarion) sp., and eventuallyM. (Malvinotarion?)cf.dereimsi.Theisaacsonilineage ranges from the Lower Pragian to Eifelian exhibiting a defined morphologic trend in the librigena. This lineage comprisesM.(Malvinotarion)isaacsoni, M.(Malvinotarion) sp. A from South Africa,M.(Malvinotarion)gauchonew species,M.(Malvinotarion)haudeinew species andM.(Malvinotarion)legrandi.A Lochkovian diversification probably took place yet an adequate assessment remains difficult. In contrast, a great evolutionary burst is recognized during the Emsian and is related to Pragian-Emsian global relative sea level curves which are coincident with those proposed from Bolivian and Argentinian basins.

Relative sea-level rise and tidal development in the Fundy tidal system

1983 ◽  
Vol 20 (10) ◽  
pp. 1554-1564 ◽  
Author(s):  
David B. Scott ◽  
David A. Greenberg
Keyword(s):  
Sea Level ◽  
High Water ◽  
Linear Increase ◽  
Published Data ◽  
Bay Of Fundy ◽  
Tidal Amplitude ◽  
Relative Sea Level ◽  
Tidal Model ◽  
Level Curves ◽  
Almost All

Previous studies of sea-level and tidal amplification in the Bay of Fundy suggested a linear increase of tidal amplitude as relative sea level rose. New data presented here are used in a numerical tidal model in an effort to reproduce paleotidal regimes over the last 7000 years. Five new sea-level curves covering the last 4000 years and some previously published data extending the record back to 7000 years before present (BP) are used as the data base. These data, when used together with the tidal model, indicate that tidal amplitudes increased much more rapidly between 7000 and 4000 years ago than in the period 4000 years ago to present. It is also shown that changes in depth within the Bay of Fundy produce little effect on the tidal amplitudes, whereas such variations in water depth on Georges Bank account for almost all the change. This calculation of tidal-amplitude changes allows calibration of sea-level curves to be made for the Bay of Fundy using higher high-water (HHW) indicators.

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