scholarly journals MAPEAMENTO GEOMORFOLÓGICO E SEDIMENTAR DE PALEOLINHAS DE COSTA NA PLATAFORMA CONTINENTAL SUL DE ALAGOAS (GEOMORPHOLOGICAL AND SEDIMENTARY MAPPING OF PALEO-LINES OF COAST IN THE CONTINENTAL PLATFORM SOUTH OF ALAGOAS)

2019 ◽  
pp. 60-79
Author(s):  
Jonas Ricardo Dos Santos ◽  
Landerlei Almeida dos Santos ◽  
Luiz Carlos Da Silveira Fontes
Keyword(s):  
Continental Shelf ◽  
Sea Level ◽  
Last Glacial Maximum ◽  
Coastal Zone ◽  
Marine Sediments ◽  
Level Variation ◽  
Sea Level Variation ◽  
The Last Glacial Maximum ◽  
Submerged Reefs ◽  
The Last Glacial

RESUMO:O objetivo desse estudo é investigar as paleolinhas de costa presentes na plataforma continental sul de Alagoas. Devido à baixa contribuição de sedimentos continentais aportados pelos rios nesta plataforma continental, as feições de fundo formadas no último ciclo de variação do nível do mar não permitiram que estas fossem totalmente soterradas. Assim, para investigar essas feições foi elaborado um modelo batimétrico a partir das Folhas de Bordos da Diretoria de Hidrografia e Navegação (DHN) da Marinha do Brasil. Posteriormente foram identificadas e mapeadas as principais anomalias no relevo (elevação ou depressão). As principais feições identificadas na plataforma continental de Alagoas foram três conjuntos de arrecifes submersos alinhados e paralelos à linha de costa, identificados a -25m, -15m e -5m, e os paleovales de Maceió, Jequiá-Jacarecica e Coruripe que ficaram evidentes no modelo batimétrico. Com isso, concluímos que a origem dos paleovales está relacionada ao último máximo glacial quando os rios escavaram a plataforma continental, e a formação dos arrecifes indicam os períodos de estabilização do nível do mar que correspondem às antigas linhas de costa.Palavras-chave: Nível do Mar; Recifes; Sedimentos Marinhos; Vales Incisos; Zona Costeira. ABSTRACT:The objective of this study is to investigate the paleo coastlines present in the southern continental shelf of Alagoas. Due to the low contribution of continental sediments contributed by the rivers in this continental shelf, the bottom features formed in the last cycle of sea level variation, did not allow that they were completely buried. Thus, to investigate these features, a bathymetric model was elaborated from the Border Sheets of the Hydrographic and Navigation Department (DHN) of the Brazilian Navy. Subsequently, the main anomalies in the relief (elevation or depression) were identified and mapped. The main features identified in the continental shelf of Alagoas were three sets of submerged reefs aligned and parallel to the coastline were identified at -25m, -15m and -5m and the paleo valleys of Maceió, Jequiá-Jacarecica and Coruripe that were evident in the bathymetric model. We conclude that the origin of the paleo valleys is related to the last glacial maximum when the rivers excavated the continental shelf and the formation of the reefs indicate the periods of stabilization of the sea level that correspond to paleo coastlines.Keywords: Sea Level; Reefs; Marine Sediments; Incised Valleys; Coastal Zone.

scholarly journals Submarine Geomorphology of the Southwestern Sardinian Continental Shelf (Mediterranean Sea): Insights into the Last Glacial Maximum Sea-Level Changes and Related Environments

Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 155
Author(s):  
Giacomo Deiana ◽  
Luciano Lecca ◽  
Rita Teresa Melis ◽  
Mauro Soldati ◽  
Valentino Demurtas ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Sea Level ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Sea Level Changes ◽  
Side Scan Sonar ◽  
Last Glacial ◽  
Depositional Processes ◽  
The Last Glacial Maximum ◽  
The Last Glacial

During the lowstand sea-level phase of the Last Glacial Maximum (LGM), a large part of the current Mediterranean continental shelf emerged. Erosional and depositional processes shaped the coastal strips, while inland areas were affected by aeolian and fluvial processes. Evidence of both the lowstand phase and the subsequent phases of eustatic sea level rise can be observed on the continental shelf of Sardinia (Italy), including submerged palaeo-shorelines and landforms, and indicators of relict coastal palaeo-environments. This paper shows the results of a high-resolution survey on the continental shelf off San Pietro Island (southwestern Sardinia). Multisensor and multiscale data—obtained by means of seismic sparker, sub-bottom profiler chirp, multibeam, side scan sonar, diving, and uncrewed aerial vehicles—made it possible to reconstruct the morphological features shaped during the LGM at depths between 125 and 135 m. In particular, tectonic controlled palaeo-cliffs affected by landslides, the mouth of a deep palaeo-valley fossilized by marine sediments and a palaeo-lagoon containing a peri-littoral thanatocenosis (18,983 ± 268 cal BP) were detected. The Younger Dryas palaeo-shorelines were reconstructed, highlighted by a very well preserved beachrock. The coastal paleo-landscape with lagoon-barrier systems and retro-littoral dunes frequented by the Mesolithic populations was reconstructed.

scholarly journals UPPER QUATERNARY SEA LEVEL FLUCTUATIONS AND STILLSTANDS ON THE CONTINENTAL SHELF OF SÃO PAULO STATE, BRAZIL: A SUMMARY

2013 ◽  
Vol 31 (5) ◽  
pp. 43 ◽  
Author(s):  
Valdenir Veronese Furtado
Keyword(s):  
Continental Shelf ◽  
Sea Level ◽  
Bottom Topography ◽  
Sao Paulo ◽  
São Paulo ◽  
Sea Level Fluctuations ◽  
Sea Level Variation ◽  
Variation Curve ◽  
The Last Glacial Maximum ◽  
The Last Glacial

ABSTRACT. Sea level fluctuations are mainly related to glacial and deglacial events. São Paulo (Brazil) continental shelf shows many features, like terraces and sedimentary scarps, associated to older periods of sea level stillstands and drowned valleys, related to regressive and transgressive events. Although these features show well defined spatial position obtained through bathymetric analysis; they lack isotopic dating, which prevents from obtaining more accurate space-temporal positions. However, correlations with similar depths along the Brazilian continental shelf and the dating of a feature in the area enabled us to elaborate an estimated sea level variation curve for São Paulo continental shelf and coastal areas, since the Last Glacial Maximum. Keywords: sea level fluctuations, bottom topography, sedimentary features, São Paulo continental shelf. RESUMO. As flutuações relativas do nível do mar, de caráter global, estão associadas a eventos climáticos de glaciação e degelo. Embora não tenham ocorrido glaciações no hemisfério sul, durante o Quaternário, exceto na Antártica, a plataforma continental de São Paulo apresenta feições morfológicas ligadas à última glaciação e ao período pós-glacial subsequente. Caracterizam-se por terraços e escarpas sedimentares, associados a períodos de estabilizações do nível do mar e paleo- canais fluviais afogados, relativos ao Último Máximo Glacial e à posterior transgressão marinha. Essas feições, embora com posições espaciais bem definidas, através de análises batimétricas, apresentam lacunas de datação isotópica que não permitem o estabelecimento de posições espaço-temporais mais precisas. No entanto, correlações com profundidades similares ao longo da plataforma continental brasileira e datação de uma feição na área, permitiram a elaboração de uma curva tentativa de variação do nível do mar, desde o Último Máximo Glacial, para a plataforma continental de São Paulo e áreas costeiras. Palavras-chave: flutuações relativas do nível do mar, topografia de fundo, feições sedimentares, plataforma continental de São Paulo.

scholarly journals Sea-level evolution of the Laptev Sea and the East Siberian Sea since the last glacial maximum

arktos ◽  
2015 ◽  
Vol 1 (1) ◽  
Author(s):  
Volker Klemann ◽  
Birgit Heim ◽  
Henning A. Bauch ◽  
Sebastian Wetterich ◽  
Thomas Opel
Keyword(s):  
Sea Level ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Laptev Sea ◽  
Last Glacial ◽  
East Siberian Sea ◽  
The Last Glacial Maximum ◽  
The Laptev Sea ◽  
The Last Glacial

Reappraisal of sea-level lowstand during the Last Glacial Maximum observed in the Bonaparte Gulf sediments, northwestern Australia

2016 ◽  
Vol 397 ◽  
pp. 373-379 ◽  
Author(s):  
Takeshige Ishiwa ◽  
Yusuke Yokoyama ◽  
Yosuke Miyairi ◽  
Stephen Obrochta ◽  
Takenori Sasaki ◽  
...  
Keyword(s):  
Sea Level ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Last Glacial ◽  
Northwestern Australia ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Coastal occupation and foraging during the last glacial maximum and early Holocene at Waterfall Bluff, eastern Pondoland, South Africa

2020 ◽  
Vol 97 ◽  
pp. 1-41 ◽  
Author(s):  
Erich C. Fisher ◽  
Hayley C. Cawthra ◽  
Irene Esteban ◽  
Antonieta Jerardino ◽  
Frank H. Neumann ◽  
...  
Keyword(s):  
South Africa ◽  
Continental Shelf ◽  
Last Glacial Maximum ◽  
Late Pleistocene ◽  
Marine Fish ◽  
Hunter Gatherers ◽  
The Holocene ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

AbstractWaterfall Bluff is a rock shelter in eastern Pondoland, South Africa, adjacent to a narrow continental shelf that limited coastline movements across glacial/interglacial cycles. The archaeological deposits are characterized by well-preserved stratigraphy, faunal, and botanical remains alongside abundant stone artifacts and other materials. A comprehensive dating protocol consisting of 5 optically stimulated luminescence ages and 51 accelerator mass spectrometry 14C ages shows that the record of hunter-gatherer occupations at Waterfall Bluff persisted from the late Pleistocene to the Holocene, spanning the last glacial maximum and the transition from the Pleistocene to the Holocene. Here, we provide detailed descriptions about the sedimentary sequence, chronology, and characteristics of the archaeological deposits at Waterfall Bluff. Remains of marine mollusks and marine fish also show, for the first time, that coastal foraging was a component of some hunter-gatherer groups’ subsistence practices during glacial phases in the late Pleistocene. The presence of marine fish and shellfish further demonstrates that hunter-gatherers selectively targeted coastal resources from intertidal and estuarine habitats. Our results therefore underscore the idea that Pondoland's coastline remained a stable and predictable point on the landscape over the last glacial/interglacial transition being well positioned for hunter-gatherers to access resources from the nearby coastline, narrow continental shelf, and inland areas.

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