scholarly journals Response of the Apodi-Mossoró estuary-incised valley system (NE Brazil) to sea-level fluctuations

2010 ◽  
Vol 58 (spe2) ◽  
pp. 13-24 ◽  
Author(s):  
Helenice Vital ◽  
Samia F.Lima Furtado ◽  
Moab Praxedes Gomes
Keyword(s):  
Sea Level ◽  
Satellite Image ◽  
Image Data ◽  
Northeastern Brazil ◽  
Sea Level Changes ◽  
Seismic Profiles ◽  
The Holocene ◽  
Incised Valley ◽  
Sea Level Fluctuations ◽  
Base Level

This study focuses on the Quaternary sea level changes in the Apodi-Mossoró Estuary and adjacent shelf, Northeastern Brazil, based on the analysis of high-resolution seismic profiles, integrated with echosounder, SRTM and satellite image data. We use these data to develop a relative stratigraphy. An incised-valley extending from the Apodi-Mossoró Estuary onto the shelf dominates the investigated area. In very shallow waters (down to 10 m depth) the channel lies mainly in a NW-SE direction, changing to NE-SW in waters below10 m, in the form of a J-shaped valley. The southern flank of the shallow channel presents an abrupt morphology, probably determined by a residual scarp due to neotectonic reactivation of a pre-existing fault. This incised-valley can be correlated with a former river valley formed during the late Pleistocene fall in sea-level. The base-level change related to this drop in sea level can be regionally expressed on seismic lines as a laterally-continuous stratigraphic surface named Horizon I, interpreted as representing the sub-aerial exposure of the continental shelf. Many incised valleys were excavated on this exposed shelf, including that of the Apodi-Mossoró Estuary and its incised valley system. This incised valley has lain buried since the Holocene transgression. The Holocene sediments present sub-horizontal layers, or they have filled the incised valley with oblique features.

Subsurface geological imaging of northeastern Tunisia during the middle to the upper Eocene: Insights from integrated geophysical interpretation

2021 ◽  
pp. 1-64
Author(s):  
Oussama Abidi ◽  
Kawthar Sebei ◽  
Adnen Amiri ◽  
Haifa Boussiga ◽  
Imen Hamdi Nasr ◽  
...  
Keyword(s):  
Sea Level ◽  
Regional Scale ◽  
Upper Eocene ◽  
Sea Level Changes ◽  
Seismic Profiles ◽  
Borehole Data ◽  
Third Order ◽  
Good Correspondence ◽  
Basin Inversion ◽  
Sea Level Fluctuations

The Middle to Upper Eocene series are characterized by multiple hiatuses related to erosion, non-deposition or condensed series in the Cap Bon and Gulf of Hammamet provinces. We performed an integrated study taking advantage from surface and subsurface geology, faunal content, borehole logs, electrical well logs, vertical seismic profiles and surface seismic sections. Calibrated seismic profiles together with borehole data analysis reveal unconformities with deep erosion, pinchouts, normal faulting and basin inversion which are dated Campanian, intra-Lutetian and Priabonian compressive phases; these events were also described at the regional scale in Tunisia. Tectonics, sea level fluctuations and climate changes closely controlled the depositional process during the Middle to Upper Eocene time. The depositional environment ranges from internal to outer platform separated by an inherited paleo-high. We determine eight third order sequences characterizing the interaction between tectonic pulsations, sea level changes and the developed accommodation space within the Middle to Upper Eocene interval. We correlate the obtained results of the Cap Bon-Gulf of Hammamet provinces with the published global charts of sea-level changes and we find a good correspondence across third order cycles. Model-based 3D inversion proved to be a solution to model the lateral and vertical lithological distribution of the Middle to Upper Eocene series.

scholarly journals INVESTIGATION OF THE INTERNAL STRUCTURE AND EVOLUTION OF THE HOLOCENE BARRIER OF MARICÁ (RIO DE JANEIRO, BRAZIL)

2015 ◽  
Vol 33 (3) ◽  
pp. 461
Author(s):  
Carolina Pereira Silvestre ◽  
André Luiz Carvalho da Silva ◽  
Maria Augusta Martins da Silva ◽  
Amilsom Rangel Rodrigues
Keyword(s):  
Internal Structure ◽  
Sea Level ◽  
Ground Penetrating Radar ◽  
Rio De Janeiro ◽  
Depositional Environments ◽  
Sea Level Changes ◽  
The Holocene ◽  
Sea Level Fluctuations ◽  
Sedimentary Architecture ◽  
Ground Penetrating

ABSTRACT. The objective of this study is the identification of the internal structure of the Holocene barrier of the Maricá coastal plain (Rio de Janeiro, Brazil) for the understanding of the evolution of this coast. The regional geomorphology is characterized by the large Maricá lagoon and by two sandy barriers which confines a series of small near-dry lagoons. Geophysical data obtained from ground-penetrating radar (GPR) images, with 400 and 200 MHz shielded antennae and borehole samples, both reaching down to about 10 meters in depth, provided information about the sedimentary architecture and geological and oceanographical processes responsible for the evolution of this area in the Holocene. The results show that the barrier internal structure is formed by a set of strata presenting different geometries, dip directions and organization, relative to the following depositional environments: dunes, washover fans, beach and tidal channels. It was possible to determine the importance of the sea level changes, longshore currents and overwash processes for the barrier development. Strong reflectors representing eolian strata dipping towards the continent point out to a phase of barrier retrogradation; afterwards, a succession of very well preserved beach paleoscarps, located south of the previous barrier, shows a phase of barrier progradation. Such evidences indicate that the barrier evolved according to the Holocene sea level fluctuations recognized for the Brazilian coast.Keywords: ground-penetrating radar, barrier-lagoon system, Holocene, Maricá coast. RESUMO. O presente estudo objetivou identificar a estrutura interna da barreira holocênica buscando compreender a evolução da planície costeira de Maricá (Rio de Janeiro). A geomorfologia regional é caracterizada pela Lagoa de Maricá e duas barreiras arenosas, separadas por pequenas lagunas colmatadas. Dados geofísicos obtidos com um georadar, com antenas de 400 e 200 MHz, e amostras de sondagem geológica, ambos até a profundidade média de 10 metros, forneceram informações sobre a arquitetura sedimentar e os processos geológicos e oceanográficos responsáveis pela evolução desta área no Holoceno. Os resultados mostram que a estrutura interna da barreira é formada por um conjunto de estratos de diferentes geometrias, direções de mergulho e modos de organização relacionados aos seguintes ambientes deposicionais: dunas, leques de arrombamento, praias e canais de maré. Essas características permitiram o entendimento da dinâmica costeira responsável pelo desenvolvimento da barreira, com destaque para as variações do nível do mar, correntes de deriva litorânea e mecanismos de sobrelavagem. Refletores marcantes representando estratos eólicos inclinados para o continente indicam uma fase de retrogradação da barreira; a esse episódio se seguiu um período marcado por sucessivas paleoescarpas de tempestade, localizadas mais ao sul, indicando uma fase de progradação. Essas evidências mostram que a barreira evoluiu de acordo com as fases de transgressão e regressão marinha do Holoceno reconhecidas para o litoral brasileiro.Palavras-chave: georadar, sistema barreira-laguna, Holoceno, litoral de Maricá.

CORRELATION OF THE BLACK, MARMARA AND AEGEAN SEAS DURING THE HOLOCENE

2017 ◽  
Author(s):  
Nikolay Esin ◽  
Nikolay Esin ◽  
Vladimir Ocherednik ◽  
Vladimir Ocherednik
Keyword(s):  
Mathematical Model ◽  
Sea Level ◽  
Black Sea ◽  
Aegean Sea ◽  
The Black Sea ◽  
Sea Level Changes ◽  
The Holocene

A mathematical model describing the change in the Black Sea level depending on the Aegean Sea level changes is presented in the article. Calculations have shown that the level of the Black Sea has been repeating the course of the Aegean Sea level for the last at least 6,000 years. And the level of the Black Sea above the Aegean Sea level in the tens of centimeters for this period of time.

BIOINDICATORS OF SEA-LEVEL FLUCTUATIONS IN SOUTHEASTERN BRAZIL: NEW DATA AND METHODOLOGICAL REVIEW

Radiocarbon ◽  
2021 ◽  
pp. 1-15
Author(s):  
Julia Caon Araujo ◽  
Kita Chaves Damasio Macario ◽  
Vinícius Nunes Moreira ◽  
Anderson dos Santos Passos ◽  
Perla Baptista de Jesus ◽  
...  
Keyword(s):  
Sea Level ◽  
Late Holocene ◽  
Data Interpretation ◽  
Progressive Increase ◽  
Southeastern Brazil ◽  
Recrystallization Process ◽  
Sea Level Changes ◽  
Sea Level Fluctuations ◽  
Data Gap ◽  
Current Zero

ABSTRACT The vermetidae fossils of Petaloconchus varians, formed by calcium carbonate, associated with their radiocarbon ages, are the most accurate indicators of paleo sea level due to their restricted occupation in the intertidal zone in the rocky shore. However, the recrystallization of minerals can affect these age calculations and, consequently, the interpretation of the data. The aim of this study is to present new indicators of paleo sea-level changes in Southeast Brazil for the last 6000 years contributing to fill the data gap for the late Holocene. The influence of the recrystallization process was successfully resolved using the CarDS protocol, enabling the separation of the original aragonite fraction by density, prior to radiocarbon dating. This avoids the rejuvenation of ages and ensures greater efficiency for data interpretation. Paleo sea-level indicators were able to show a progressive increase in sea level up to the transgressive maximum of 4.15 m in 3700 BP years, followed by a regression to the current zero. This regression seems to have in addition, here we reinforce the reliability of the use of fossil vermetids as indicators of sea-level fluctuations.

Relative sea level changes during the Holocene in the Sisimiut area, south-western Greenland

2011 ◽  
Vol 26 (4) ◽  
pp. 353-361 ◽  
Author(s):  
Ole Bennike ◽  
Bernd Wagner ◽  
Andreas Richter
Keyword(s):  
Sea Level ◽  
Sea Level Changes ◽  
Relative Sea Level ◽  
The Holocene

Impacts of sea-level changes on mangroves from southeastern Brazil during the Holocene and Anthropocene using a multi-proxy approach

Geomorphology ◽  
2021 ◽  
pp. 107860
Author(s):  
Bettina S. Bozi ◽  
Beatriz L. Figueiredo ◽  
Erika Rodrigues ◽  
Marcelo C.L. Cohen ◽  
Luiz C.R. Pessenda ◽  
...  
Keyword(s):  
Sea Level ◽  
Southeastern Brazil ◽  
Sea Level Changes ◽  
The Holocene

scholarly journals Aquifer-eustasy as the main driver of short-term sea-level fluctuations during Cretaceous hothouse climate phases

2019 ◽  
Vol 498 (1) ◽  
pp. 9-38 ◽  
Author(s):  
Benjamin Sames ◽  
M. Wagreich ◽  
C. P. Conrad ◽  
S. Iqbal
Keyword(s):  
Sea Level ◽  
Phase Relationship ◽  
Sea Level Changes ◽  
Short Term ◽  
Groundwater Levels ◽  
Sequence Stratigraphic ◽  
Sea Level Fluctuations ◽  
Minimum Estimate ◽  
Underlying Mechanisms ◽  
Continental Ice Sheets

AbstractA review of short-term (<3 myr: c. 100 kyr to 2.4 myr) Cretaceous sea-level fluctuations of several tens of metres indicates recent fundamental progress in understanding the underlying mechanisms for eustasy, both in timing and in correlation. Cretaceous third- and fourth-order hothouse sea-level changes, the sequence-stratigraphic framework, are linked to Milankovitch-type climate cycles, especially the longer-period sequence-building bands of 405 kyr and 1.2 myr. In the absence of continental ice sheets during Cretaceous hothouse phases (e.g. Cenomanian–Turonian), growing evidence indicates groundwater-related sea-level cycles: (1) the existence of Milankovitch-type humid-arid climate oscillations, proven via intense humid weathering records during times of regression and sea-level lowstands; (2) missing or inverse relationships of sea-level and the marine δ18O archives, i.e. the lack of a pronounced positive excursion, cooling signal during sea-level lowstands; and (3) the anti-phase relationship of sea and lake levels, attesting to high groundwater levels and charged continental aquifers during sea-level lowstands. This substantiates the aquifer-eustasy hypothesis. Rates of aquifer-eustatic sea-level change remain hard to decipher; however, reconstructions range from a very conservative minimum estimate of 0.04 mm a−1 (longer time intervals) to 0.7 mm a−1 (shorter, probably asymmetric cycles). Remarkably, aquifer-eustasy is recognized as a significant component for the Anthropocene sea-level budget.

Foraminiferal response to Albian relative sea-level changes in northwestern and central Alberta, Canada

1999 ◽  
Vol 36 (10) ◽  
pp. 1617-1643 ◽  
Author(s):  
Rebecca A Stritch ◽  
Claudia J Schröder-Adams
Keyword(s):  
Sea Level ◽  
Bottom Water ◽  
Gradual Increase ◽  
Western Canada ◽  
Sea Level Changes ◽  
Relative Sea Level ◽  
Sea Level Fluctuations ◽  
Faunal Assemblages ◽  
Water Oxygen ◽  
Southern Alberta

Albian foraminiferal assemblages from three wells in northwestern (Imperial Spirit River No. 1, 12-20-78-6W6), central (AngloHome C&E Fort Augustus No. 1, 7-29-55-21W4), and southern Alberta (Amoco B1 Youngstown, 6-34-30-8W4) provide the basis to track a fluctuating sea-level history in western Canada. Two global second-order marine cycles (Kiowa - Skull Creek and Greenhorn) were punctuated by higher frequency relative sea-level cycles expressed during the time of the Moosebar-Clearwater, Hulcross, Joli Fou, and Mowry seas. A total of 34 genera and 93 subgeneric taxa are recognized in these Albian-age strata. Foraminiferal abundance and species diversity of the latest Albian Mowry Sea were higher than in the early to middle Albian Moosebar-Clearwater and Hulcross seas. The two earliest paleo-seas were shallow embayments of the Boreal Sea, and relative sea-level fluctuations caused variable marine to brackish conditions expressed in a variety of faunal assemblages. Towards the late Albian, relative sea level rose, deepening the basin and establishing increased marine conditions and more favourable habitats for foraminifera. In the deeper Joli Fou Seaway and Mowry Sea, however, reduced bottom water oxygen through stratification or stagnant circulation caused times of diminished benthic faunas. The Bluesky Formation in northwestern Alberta contains the initial transgression of the early Albian Moosebar-Clearwater Sea and is marked by a sudden faunal increase. In contrast, transgression by the late late Albian Mowry Sea was associated with a gradual increase of foraminiferal faunas. Numerous agglutinated species range throughout the entire Albian, absent only at times of basin shallowing. However, each major marine incursion throughout the Albian introduced new taxa.

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