Postglacial sedimentary and geomorphological evolution of a small sub-Antarctic fjord landscape, Stromness Bay, South Georgia

2012 ◽  
Vol 25 (3) ◽  
pp. 409-419 ◽  
Author(s):  
Nathalie Van Der Putten ◽  
Cyriel Verbruggen ◽  
Helena Alexanderson ◽  
Svante Björck ◽  
Bart Van De Vijver
Keyword(s):  
Sea Level ◽  
Late Glacial ◽  
Sea Level Changes ◽  
Freshwater Environment ◽  
Radiocarbon Dates ◽  
South Georgia ◽  
Isostatic Rebound ◽  
Late Glacial And Holocene ◽  
Geomorphological Evolution

AbstractA detailed stratigraphical, palaeoecological and geomorphological reconstruction of a fjord head on South Georgia (Husvik, Stromness Bay) is presented. Six sites were chosen to reconstruct the lithostratigraphy of the area by means of coring. A maximum depth of 11 m was attained and the sediments encountered vary from coarse gravel over sands to fine silts with, in some cases, intercalated peat layers. Diatom analysis allowed determination of whether the sedimentological units were deposited in a marine or freshwater environment. Six radiocarbon dates constrain the chronology. Deglaciation of the area was completed in the early Holocene and the postglacial geomorphological evolution of Husdal (unofficial name) was controlled by fluvio-deltaic deposition and sea level changes. Relative sea level rise was faster than, or kept pace with the isostatic rebound of the land. Our results challenge the presence of Late Glacial and Holocene raised beach deposits in the area as reported in earlier geomorphological studies.

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

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.

Late-Glacial and Early Holocene Sea-Level Fluctuations in the Central Puget Lowland, Washington, Inferred from Lake Sediments

1994 ◽  
Vol 42 (2) ◽  
pp. 149-161 ◽  
Author(s):  
Karl Anundsen ◽  
Sally Abella ◽  
Estella Leopold ◽  
Minze Stuiver ◽  
Sheila Turner
Keyword(s):  
Sea Level ◽  
Late Glacial ◽  
Early Holocene ◽  
Pollen Record ◽  
Sea Level Changes ◽  
Radiocarbon Dates ◽  
Sea Level Fluctuations ◽  
Lake Outlet ◽  
Basal Section ◽  
Holocene Sea Level

AbstractAnalyses of sediments, diatoms, and pollen in a 12.65-m-long sediment core taken from Lake Carpenter in the central Puget Lowland, Washington, provide detailed information regarding the history of deglaciation and late-glacial/early Holocene sea-level changes. The lake outlet, now 8.2 m above sea level, has been lowered 1-1.5 m by postglacial erosion. The lithology and pollen record suggest that no lengthy hiatuses in sedimentation have occurred. The basal sediments are glacialmarine and contain shell fragments and brackish/marine diatoms. Freshwater sediments above the basal section are interrupted only by a short section containing few fossils, most of which are brackish to marine indicators, and by the Mazama tephra at 9.5 m. The pollen record in the basal 4 m reveals a Pinus zone (ca. 13,850-11,000 yr B.P.) with a brief peak of Picea at ca. 13,700 yr B.P., and an Alnus/Pseudotsuga zone (ca. 11,000-6500 yr B.P.). The chronology is based on nine radiocarbon ages. A relative lowering of sea level below the 9.5-m threshold is recorded in the core at 12.41 m and dates 13,850 to 13,700 yr B.P. A marine episode occurred about 13,600 yr B.P., implying that relative sea-level temporarily rose above 9.5 m. No subsequent transgressions above the 9.5-m level have been recorded. Comparison of six radiocarbon dates ≥13,600 yr B.P. suggest that the marine reservoir correction of 760 yr currently used for this area may be too high for this time period.

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

1977 ◽  
Vol 14 (9) ◽  
pp. 2121-2126 ◽  
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.

scholarly journals AN APPROACH TO THE CONTRIBUTION OF ANTHROPOGENIC ACTIONS FOR THE ARARUAMA LAGOONAL SYSTEM (SE BRAZIL) GEOMORPHOLOGICAL EVOLUTION / UMA ABORDAGEM SOBRE A INFLUÊNCIA ANTROPOGÊNICA NA EVOLUÇÃO GEOMORFOLÓGICA DO SISTEMA LAGUNAR DE ARARUAMA (SE, BRASIL)

2018 ◽  
Vol 3 (2) ◽  
pp. 108-120
Author(s):  
Olegário Nelson Azevedo Pereira ◽  
Maria Antonieta Da Conceição Rodrigues ◽  
João Manuel Alveirinho Dias
Keyword(s):  
Sea Level ◽  
Rio De Janeiro ◽  
Historical Documents ◽  
Before Present ◽  
Sea Level Changes ◽  
Economic Exploitation ◽  
Se Brazil ◽  
Geomorphological Evolution ◽  
Janeiro State ◽  
Cabo Frio

The first studies regarding the constitution of the Araruama lagoonal system, located in the Rio de Janeiro state (SE Brazil), were carried out by Alberto Ribeiro Lamego. This author supported the thesis that it had resulted from the formation of a sand barrier (called Massambaba) due to the longitudinal transport of large quantities of sediments through coastal drift currents, and the growth of spits parallel to the shoreline. However, most recent studies largely rejected it, sustaining that the confinement of these hydric environments was the result of the growth of two sand barriers during the Pleistocene and Holocene times (120.000 to 7.000 years before present - BP) due to the sea level changes. The hypothesis that we suggest, is that both propositions are acceptable and complementary. This study aims to demonstrate that, despite the opinions on the formation of the double sand barrier, deposition of sediments by coastal drift currents at the end of the Holocene, and especially in recent chronologies, also contributed to the establishment of this lagoon system. In our opinion, the increased sediment supplies due to human activities contributed to the formation of the inner spits and the nearby sea sandbar. Its orientation was influenced by the existence of the island of Cabo Frio, that allowed the formation of the tombolo that almost connected it to the continent. Through the analysis of historical and cartographic documents related to the colonization and economic exploitation of the region, it is evident that the anthropogenic actions played a significant role in the sandy spits formation. Of these, special emphasis is placed on the agriculture and deforestation that contributed to the increase of sedimentary accumulation. This work demonstrate that the analysis of historical documents can provide information and contribute to the understanding of recent coastal developments. ResumoOs primeiros estudos sobre a constituição do sistema lagunar de Araruama, localizado no estado do Rio de Janeiro (SE Brasil), foram realizados por Alberto Ribeiro Lamego. Este autor apoiou a tese de que este sistema lagunar resultou da formação de uma barreira arenosa (denominada Massambaba) na sequência do transporte longitudinal de grandes quantidades de sedimentos através das correntes costeiras de deriva litorânea e ao crescimento de flechas arenosas paralelas à linha de costa. No entanto, estudos mais recentes, rejeitaram amplamente esta hipótese, e sugeriram que o confinamento desses ambientes lagunares resultou do crescimento de duas barreiras arenosas na sequência de mudanças no nível do mar ocorridas durante os períodos Pleistocénicos e Holocênico (120.000 a 7.000 anos antes do presente - BP). A hipótese que sugerimos é que ambas as hipóteses são aceitáveis e complementares. Este estudo tem como objetivo demonstrar que, apesar das opiniões sobre a formação da dupla barreira de areia, a deposição de sedimentos por correntes de deriva costeira no final do Holoceno, e principalmente em cronologias recentes, também contribuiu para o estabelecimento deste sistema lagunar. Em nossa opinião, o aumento do fornecimento de sedimentos devido às atividades humanas contribuiu para a formação das flechas arenosas interiores e do banco de areia exterior, próximo do mar. A sua orientação foi influenciada pela existência da ilha de Cabo Frio, que permitiu a formação do tombolo que quase a conectou ao continente.Através da análise de documentos históricos e cartográficos relacionados com a colonização e exploração econômica da região, evidencia-se que as ações antropogênicas tiveram um papel significativo na formação das flechas arenosas. De entre estas, salienta-se especialmente a agricultura e o desmatamento que contribuíram para o aumento da acumulação sedimentar. Este trabalho evidencia que a análise de documentos históricos pode fornecer informações e contribuir para a compreensão da evolução recente do litoral.

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

2002 ◽  
Vol 97 ◽  
pp. 171-200 ◽  
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.

scholarly journals An evaluation of climate, crustal movement and base level controls on the Middle-Late Pleistocene development of the River Severn, U.K.

2002 ◽  
Vol 81 (3-4) ◽  
pp. 329-338 ◽  
Author(s):  
D. Maddy
Keyword(s):  
Sea Level ◽  
Late Glacial ◽  
High Energy ◽  
Cold Climate ◽  
Faunal Remains ◽  
Sea Level Changes ◽  
Climate Conditions ◽  
Oxygen Isotope Stage ◽  
Base Level

AbstractThe Pleistocene development of the lower Severn valley is recorded in the fluvial sediments of the Mathon and Severn Valley Formations and their relationship to the glacigenic Wolston (Oxygen Isotope Stage 12), Ridgacre (OIS 6) and Stockport (OIS 2) Formations. The most complete stratigraphical record is that of the Severn Valley Formation, which post-dates the Anglian Wolston Formation and comprises a flight of river terraces, the highest of which is c.50 m above the present river. The terrace staircase indicates that the Severn has progressively incised its valley during the post-Anglian period. The terrace sediments are predominantly composed of fluvially deposited sands and gravels, largely the result of deposition in high-energy rivers under cold-climate conditions. Occasionally towards the base of these terrace deposits low-energy fluvial facies are preserved which contain faunal remains and yield geochronology which support their correlation with interglacial conditions. This simple stratigraphy supports a climate-driven model for the timing of terrace aggradation and incision, with the incision mode at its most effective during the cold-warm transitions and the aggradational mode at its most effective during warm-cold climate transitions. The chronology of terrace aggradation in the lower Severn seems to correspond with the Milankovitch lOOka climate cycles. The timing of incision events suggests that base level (eustatic sea-level) changes do not play a significant role i.e. incision occurs as sea-level is rising.Although climate change is significant in governing the timing of incision, the long-term incision of the River Severn appears to be driven by crustal uplift. A long-term incision rate of 0.15 m ka1, calculated using the base of the terrace deposits, is believed to closely equate with the long-term uplift rate. Superimposed on this long-term uplift are periods of complex terrace sequence development resulting from rapid incision during periods of glacio-isostatic rebound, with large incision events reflecting the rebound adjustment to late glacial stage isostatic depression. However, in no case in the Severn valley has glacial encroachment led to enhanced incision, suggesting that there has been no additional uplift resulting from isostatic compensation for glacial erosion.

Late-Glacial and Holocene Glacier Fluctuations and Environmental Change on South Georgia, Southern Ocean

1989 ◽  
Vol 31 (2) ◽  
pp. 210-228 ◽  
Author(s):  
Chalmers M. Clapperton ◽  
David E. Sugden ◽  
Jacqueline Birnie ◽  
Mandy J. Wilson
Keyword(s):  
Environmental Change ◽  
Ice Cores ◽  
Late Glacial ◽  
Environmental Indicators ◽  
Temperature Changes ◽  
South Georgia ◽  
Ice Cap ◽  
Late Glacial And Holocene ◽  
Climatic Cooling ◽  
The Antarctic

AbstractSouth Georgia provides a terrestrial record of postglacial environmental change from a largely oceanic zone of the Earth. The record is representative of the southern westerlies and provides a link between Antarctica and the temperate zones of southern South America. Evidence from glacial geomorphology, slope stratigraphy, and analyses of environmental indicators in peat and lake cores is used to interpret this record. Wastage of the full-glacial ice cap was interrupted by a late-glacial stade of the outlet and valley glaciers before ca. 10,000 yr B.P. Plant growth had begun at low altitude (<50 m) on the sheltered (lee side) northeast coast within the late-glacial moraine limits by 9700 yr B.P. Environmental conditions on slopes above 80 m probably were too rigorous for a stable vegetation cover until ca. 6400 yr B.P. This was followed by a period from 5600 to 4800 yr B.P. when conditions were warmer than at present by up to 0.6°C. Periods of climatic cooling occurred at ca. 4800-3800 yr B.P., ca. 3400-1800 yr B.P., and within the last 1400 yr. The most extensive Holocene advance of South Georgia glaciers culminated just before 2200 yr B.P. These Holocene temperature changes of between 0.5 and 1.0°C are comparable in scale and timing to those identified from recent analyses of Vostok ice cores from the Antarctic ice sheet.

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).

Submerged speleothem in Malta indicates tectonic stability throughout the Holocene

The Holocene ◽  
2018 ◽  
Vol 28 (10) ◽  
pp. 1588-1597 ◽  
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.

Sign in / Sign up

Export Citation Format

Share Document