Morphological and sedimentological changes of subaqueous dunes in the tide-dominated environment, Gyeonggi Bay

2014 ◽  
Vol 38 (6) ◽  
pp. 761-770
Author(s):  
Byung-Cheol Kum
Keyword(s):  
Subaqueous Dunes

DETERMINING RESERVOIR CONTINUITY IN THE LAMINARIA FORMATION BY INTEGRATED GEOLOGICAL STUDY

2001 ◽  
Vol 41 (1) ◽  
pp. 415 ◽  
Author(s):  
D.C. Barr ◽  
A.F. Kennaird ◽  
J. Fowles ◽  
N.G. Marshall ◽  
V.L. Cutten
Keyword(s):  
Grain Size ◽  
High Resolution ◽  
Sea Level ◽  
Clay Content ◽  
Coarse Grained ◽  
Log Data ◽  
Reservoir Performance ◽  
Subaqueous Dunes ◽  
Reservoir Sandstones ◽  
Reservoir Potential

A recent geological study, integrating sedimentological core-derived descriptions with ichnofacies, high resolution biostratigraphy and wireline log data, establishes the lateral continuity of reservoir sandstones in the Laminaria Formation. By defining a hierarchy of bedding surfaces and correlating this hierarchy with major correlation surfaces, and lateral and vertical facies patterns, it was possible to identify genetically related sediment packages between 12 wells in the study area.The Laminaria Formation is interpreted to have been deposited on a tide and storm-influenced marine shelf, and was strongly influenced by fluctuations in sea level. The formation consists of a series of progradational parasequences, each dominated by good quality, fine- to medium-grained sandstone. These sandstones are believed to have formed as subaqueous dunes or sand banks, exhibiting blanket-like geometry over much of the area. Several sandstones are capped by thin, intraclast-rich layers that mark transgressive surfaces of erosion. These surfaces can be traced across the study area and, therefore, act as important correlative markers.Evidence of gradual transgression, which ultimately led to the drowning of the system, is seen near the top of the formation. Clay content increases upward, while grain size and bedding thickness generally decrease. However, several thin, laterally extensive, medium- to coarse-grained sandstones exist, improving reservoir potential in this part of the formation.The results of this study are being used to estimate reserves and assess reservoir performance, and will serve as a basis for future geological and petrophysical modelling work.

Predicting the migration rates of subaqueous dunes

1996 ◽  
Vol 32 (10) ◽  
pp. 3207-3217 ◽  
Author(s):  
David Mohrig ◽  
J. Dungan Smith
Keyword(s):  
Migration Rates ◽  
Subaqueous Dunes

Bed shear stress over subaqueous dunes, and the transition to upper-stage plane beds

Sedimentology ◽  
1982 ◽  
Vol 29 (5) ◽  
pp. 743-744 ◽  
Author(s):  
TIMOTHY R. H. DAVIES
Keyword(s):  
Shear Stress ◽  
Bed Shear Stress ◽  
Subaqueous Dunes ◽  
Upper Stage

Subaqueous Dunes Over Sand Ridges on the Murcia Outer Shelf

2016 ◽  
pp. 187-192 ◽  
Author(s):  
R. Durán ◽  
J. Guillén ◽  
J. Rivera ◽  
A. Muñoz ◽  
F. J. Lobo ◽  
...  
Keyword(s):  
Outer Shelf ◽  
Sand Ridges ◽  
Subaqueous Dunes

First articulated stalked crinoids from the Mesozoic of South America: two new species from the Lower Cretaceous of the Neuquén Basin, west-central Argentina

2020 ◽  
Vol 94 (4) ◽  
pp. 716-733
Author(s):  
Darío G. Lazo ◽  
Graciela S. Bressan ◽  
Ernesto Schwarz ◽  
Gonzalo D. Veiga
Keyword(s):  
New Species ◽  
Lower Cretaceous ◽  
Carbonate Sediments ◽  
Exceptional Preservation ◽  
Central Argentina ◽  
West Central ◽  
Subaqueous Dunes ◽  
Neuquen Basin ◽  
Neuquén Basin ◽  
Slender Column

AbstractTwo new isocrinids are described from the Lower Cretaceous Agrio Formation of the Neuquén Basin, west-central Argentina. Isocrinus (Chladocrinus) covuncoensis new species is based on several beautifully preserved specimens from Valanginian beds of the Pilmatué Member. It is characterized by a small size, multiramose crown with six arm divisions, 240 arm tips, mostly isotomous branching, seven (or rarely eight) secundibrachials, smooth and stout column, short noditaxis, and pentalobate columnals. The species occurs in a 30 m thick interval of cross-bedded sandstones and mixed clastic-carbonate sediments that represent the migration of large, tidally influenced, subaqueous dunes developed in the offshore. Sudden burial of crinoids that dwelled on the dune toes and interdunes, possibly by the acceleration of the lee face migration, provided the exceptional preservation of specimens and thus this finding can be considered as a local crinoid Konservat Lagerstätte. Isocrinus (Chladocrinus) pehuenchensis new species is described from a single articulated specimen preserved in a silty calcareous concretion collected from a late Hauterivian concretion level of the Agua de la Mula Member. It is characterized by isotomous branching, eight or nine secundibrachials (IIBr), slender column ornamented with medial ridge of fine tubercles, interradius acuminated with fine tubercles on its tip, short noditaxis, and pentastellate columnals. It is associated with low-energy fall-out deposits in the offshore. The excellent state of preservation was due to an early cementation process by carbonate that enhanced lithification around the specimen.UUID: http://zoobank.org/4763ae70-9d0a-4015-b1c9-6a7ceeedfb1a

Effect of Coriolis force on the linear stability of subaqueous dunes with erodible and non-erodible beds

2021 ◽  
Vol 419 ◽  
pp. 127745
Author(s):  
Ankit Singh ◽  
P. Deepu
Keyword(s):  
Linear Stability ◽  
Coriolis Force ◽  
Subaqueous Dunes ◽  
Erodible Beds

Bio and Anthropogenic Disturbance of Maërl Communities Settled on Subaqueous Dunes on the Mar Menor Continental Shelf (Western Mediterranean)

2016 ◽  
pp. 215-219 ◽  
Author(s):  
M. Demestre ◽  
A. Muntadas ◽  
P. Sanchez ◽  
A. Garcia-de-Vinuesa ◽  
J. Mas ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Anthropogenic Disturbance ◽  
Western Mediterranean ◽  
Mar Menor ◽  
Subaqueous Dunes

scholarly journals GEOACOUSTIC PATTERNS OF THE GUAÍBA RIVER BOTTOM AND SUBBOTTOM AND THEIR RELATIONSHIP WITH SEDIMENTARY AND HYDRODYNAMIC PROCESSES

2019 ◽  
Vol 37 (1) ◽  
pp. 105 ◽  
Author(s):  
Fernando Comerlato Scottá ◽  
Mauro Michelena Andrade ◽  
Vicente Oliveira Silva Junior ◽  
Natacha Oliveira ◽  
Jair Weschenfelder ◽  
...  
Keyword(s):  
Spatial Arrangement ◽  
Human Action ◽  
Side Scan Sonar ◽  
Fine Sediments ◽  
Navigation Channel ◽  
Subaqueous Dunes ◽  
Hydrodynamic Processes ◽  
Surrounding Areas ◽  
Sandy Sediments ◽  
River Bottom

ABSTRACT. This work aimed at studying the bottom and sub-bottom geoacoustics of the Guaíba River, whose echo patterns are related to hydrodynamic patterns and sedimentary processes. A total of 324 km of seismic transects were surveyed using the Stratabox high-frequency (10 kHz) profiler with concomitant imaging using a side-scan sonar in the northern and central areas of the Guaíba system. The records were interpreted with the aid of complementary data (bathymetry and bottom samples), and maps containing the spatial arrangement of echo-characters were developed. The echo-characters were classified into seven different types according to the presence of sediments controlled by the hydrodynamics of the system or modified by human action. In general, the echoes related to the deposition of fine sediments occurred in deeper areas, the navigation channel or surrounding areas. The echoes in the shallower areas presented strong acoustic reflectivity at sites with lower deposition of fine sediments and predominance of sandy sediments. The occurrence and morphology of asymmetric subaqueous dunes indicated a predominant north-to-south flow and a river behavior.Keywords: shallow geophysics, sedimentology, hydrodynamics, geoprocessing.RESUMO. Este trabalho tem por objetivo o estudo geoacústico de fundo e subfundo do rio Guaíba, cujos padrões de ecos são relacionados aos padrões hidrodinâmicos e aos processos sedimentares atuantes. Foram levantados 324 km de perfis sísmicos em extensão, com o perfilador de alta frequência (10 kHz) Stratabox e concomitante imageamento com Sonar de Varredura Lateral nas áreas Norte e Central do Guaíba. Os registros foram interpretados com o auxílio de dados complementares (batimetria e amostras de fundo) e foram confeccionados mapas com a disposição espacial dos eco-caráteres. Os eco-caráteres foram classificados em sete diferentes tipos, de acordo com a presença de sedimentos controlados pela hidrodinâmica do sistema ou modificados pela ação humana. De uma forma geral, os ecos relacionados à deposição de sedimentos finos ocorrem nas áreas mais profundas, no canal de navegação ou adjacências. Os ecos nas áreas mais rasas apresentam forte refletividade acústica, em locais com menor deposição de sedimentos finos e predomínio de sedimentos arenosos. A ocorrência e morfologia de dunas subaquosas assimétricas indicam um fluxo preponderante no sentido Norte – Sul e um comportamento fluvial do sistema aquático.Palavras-chave: geofísica rasa, sedimentologia, hidrodinâmica, geoprocessamento.

Subaqueous dunes of Northern Shelf of Rio Grande do Norte (Brazil)

2017 ◽  
Author(s):  
Francisco C. Nascimento Neto ◽  
Isabelle R. F. Araujo ◽  
Helenice Vital
Keyword(s):  
Rio Grande ◽  
Northern Shelf ◽  
Subaqueous Dunes
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