Zeitschriftenartikel: „Morphology of the continental shelf“

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Hải, Nguyễn Tiến, Phùng Văn Phách und K. Stattegger. „Xác định cấu trúc hình thái của châu thổ cửu long trên thềm lục địa ven bờ Cà Mau trên cơ sở tài liệu địa chấn nông phân giải cao“. VIETNAM JOURNAL OF EARTH SCIENCES 30, Nr. 4 (13.05.2008): 356–62. http://dx.doi.org/10.15625/0866-7187/31/4/11777.

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Goes, Enatielly Rosane, und Antônio Vicente Ferreira Júnior. „Caracterização Morfossedimentar da Plataforma Continental Brasileira (Morphosedimentary characterization of the Brazilian Continental Shelf )“. Revista Brasileira de Geografia Física 10, Nr. 5 (09.07.2017): 1595. http://dx.doi.org/10.26848/rbgf.v.10.5.p1595-1613.

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Este trabalho discute as diferenciações existentes ao longo da plataforma continental brasileira, bem como sua gênese e evolução. Foi realizada uma pesquisa bibliográfica afim de evidenciar as particularidades da mesma, especialmente do setor pernambucano, reconhecido como último elo de ligação entre os continentes americano e africano. A morfologia e as características sedimentológicas da área em estudo são altamente influenciadas por diferentes condições climáticas, hidrológicas e aporte sedimentar continental ao longo do território brasileiro, além de diferentes estágios de formação e evolução da margem continental brasileira. Assim estes fatores promovem quatro grandes diferentes setores na plataforma continental brasileira. O setor norte, marcado pela largura ampla e predomínio de sedimentação terrígena, recebe grande influência continental pela presença de grandes rios e clima equatorial. O setor nordeste, mais estreito e com predomínio de sedimentação biogênica, recebe grande influência marinha, com território continental desprovido de grandes rios, de clima tropical e semiárido. A porção central da plataforma continental brasileira apresenta as mesmas características hidrológica, climática e sedimentar do setor anterior, contudo com larguras geralmente menores, como é o caso da plataforma adjacente ao município de Salvador. No setor sul volta a se apresentar mais progradante com predomínio de sedimentação terrígena, voltando a receber vasta influência continental, com ocorrência de rios mais relevantes e clima subtropical. A B S T R A C TThis paper discusses the existing differences along the Brazilian continental shelf, as well as its genesis and evolution. A bibliographical research was carried out in order to highlight its peculiarities, especially in Pernambuco’s sector recognized as the last link between the American and African continents. The morphology and sedimentological characteristics of the studied area are highly influenced by different climatic, hydrological and continental sedimentary contribution conditions along the Brazilian territory, besides different stages of formation and evolution of the Brazilian continental margin. Thus, these factors are responsible for four large sectors in the Brazilian continental shelf. The northern sector, marked by wide width and predominance of terrigenous sedimentation, receives great continental influence, due to the presence of large rivers and equatorial climate. The Northeast sector, which is narrower and has a predominance of biogenic sedimentation, receives great marine influence, the continental territory is devoided of large rivers, with tropical and semi-arid climate. The central portion of the Brazilian continental shelf presents the same hydrological, climatic and sedimentary characteristics of the previous sector, however usually with smaller widths; this is the case of the platform adjacent to the municipality of Salvador. The southern sector presents more prograde with a predominance of terrigenous sedimentation, receiving once again vast continental influence, with more relevant rivers and subtropical climate.Keywords: morphology, sedimentary dynamics, continental margin, Pernambuco.

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Gutierrez-Mas, J. M., A. Lopez-Galindo und F. Lopez-Aguayo. „Clay minerals in recent sediments of the continental shelf and the Bay of Cádiz (SW Spain)“. Clay Minerals 32, Nr. 4 (Dezember 1997): 507–15. http://dx.doi.org/10.1180/claymin.1997.032.4.02.

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AbstractThe distribution of clay minerals in recent sediments on the continental shelf and in the Bay of Cádiz has been analysed as part of a wider study of sedimentary exchange between the continent and the continental margin. The clay minerals included in the muddy sediments consist mainly of illite, kaolinite, smectite, randomly mixed-layered illite-smectite, chlorite, vermiculite and randomly mixed-layered illite-chlorite. Distribution of the minerals indicates that inheritance from the adjacent continental areas is the most important process involved.The relations between the clay minerals were established by Q-mode and R-mode factor analysis. The main clay mineral associations are: (1) illite-kaolinite, (2) smectite-random mixed-layered illitesmectite, and (3) kaolinite-random mixed-layered illite-smectite-vermiculite. The main sources of sediment supply to the continental shelf are the Guadalquivir and Guadiana rivers. Sediment from these rivers and from the rivers flowing into the Bay of Cádiz (mainly the Guadalete) is transported to the part of the shelf outside the bay by ebb-tide currents. The path of this outflow to the continental shelf, where the sediment is partially deposited, is influenced by the morphology of the coast and by hydrodynamic processes.

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ten Brink, Uri S., und Christopher Schneider. „Glacial morphology and depositional sequences of the Antarctic continental shelf“. Geology 23, Nr. 7 (1995): 580. http://dx.doi.org/10.1130/0091-7613(1995)023<0580:gmadso>2.3.co;2.

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Tayton, J. W., A. D. Albani und J. G. Hoffman. „Cainozoic morphology of the inner continental shelf near Sydney, N.S.W“. Journal and proceedings of the Royal Society of New South Wales 121, Nr. 1-2 (Oktober 1988): 11–28. http://dx.doi.org/10.5962/p.361251.

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Eakins, Barry W., Margot L. Bohan, Andrew A. Armstrong, Meredith Westington, Jennifer Jencks, Elliot Lim, Susan J. McLean und Robin R. Warnken. „NOAA's Role in Defining the U.S. Extended Continental Shelf“. Marine Technology Society Journal 49, Nr. 2 (01.03.2015): 204–10. http://dx.doi.org/10.4031/mtsj.49.2.17.

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AbstractThe legal continental shelf is a maritime zone that typically goes out to 200 nautical miles from shore. It may, however, be extended beyond 200 nautical miles, based in part on the morphology of the continental margin. The United Nations Convention on the Law of the Sea sets forth the requirements for how coastal countries can legally define such an extended continental shelf (ECS), within which they may manage the natural resources on and below the seabed. The National Oceanic and Atmospheric Administration (NOAA), along with the U.S. Geological Survey and the U.S. Department of State, is working to map, analyze, and define the seaward extent of the U.S. ECS. New advances in maritime technologies, such as improved multibeam echosounders, and associated visualization and analysis software aid in this effort by enabling project scientists to better understand seafloor geomorphology and interpret local and regional geologic processes. Marine geophysical data collected during this project are publicly available, benefiting the broader scientific community and public through timely data access and long-term preservation. To date, NOAA has led more than 30 high-resolution surveys and mapped more than 2 million square kilometers of sea floor in support of the U.S. ECS effort. New discoveries have been made during these surveys, and the data have contributed to better understanding of the morphology and geology of the U.S. continental margins.

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Chaytor, Jason. „Geologic features at the continental shelf edge and their influence on acoustic propagation and scattering“. Journal of the Acoustical Society of America 152, Nr. 4 (Oktober 2022): A25. http://dx.doi.org/10.1121/10.0015420.

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The continental shelf edge, encompassing the seaward edge of the continental shelf and the upper continental slope, is a region of significant variation in the physical, chemical, and biological character of the ocean and seabed. The surficial and shallow sub-surface geologic features across this transition from the seaward-dipping shelf to the steeper upper slope reflect a spectrum of modern and antecedent constructional and destructional processes, each affecting acoustic propagation and scattering. Geologic features across the shelf edge are created by eustatic and regional sea level change, glacial processes, development and abandonment of fluvial pathways, and variations in slope stability. These geologic features are further modified by seasonal and persistent water column and bottom-water boundary layer physical processes, diagenetic modification, and biological activity supported by nutrient rich upwelling. Using examples from the southern New England shelf edge (SNESE), the scale, morphology, formative processes of shelf edge features and their impact on acoustic propagation and scattering will be presented. The SNESE has been shaped by a combination of glacial and interglacial processes resulting in a region with a complex seabed environment characterized by features such as variable surficial sediment, pockmarks, landslide scars, and submarine canyons. [Work supported by the Office of Naval Research.]

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Kluiving, S. J., L. R. Bartek und F. M. van der Wateren. „Multi-scale analyses of subglacial and glaciomarine deposits from the Ross Sea continental shelf, Antarctica“. Annals of Glaciology 28 (1999): 90–96. http://dx.doi.org/10.3189/172756499781822039.

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AbstractPiston cores collected from the Ross Sea continental shelf, Antarctica, were studied as part of a multi-scale analysis of glacial and glaciomarine stratigraphy and sedimentology. The objective of these analyses was to differentiate glaciomarine sediments from subglacially deformed tills. Results from analyses of microstructures, lithofacies and seafloor morphology indicate that glaciomarine and subglacially deformed sediments can be clearly distinguished and further characterized by variations in textural parameters. Overcompaction, as well as presence of stratification in sediments, are not considered critical criteria for distinguishing subglacial from glaciomarine deposits. Trough-shaped morphologies and fluted terrain strongly correlate with S-C and S-C-C- type shear-zone microstructures and indicate that subglacial deformation is an important process in these areas, confirming the presence of grounded ice on the shelf during formation of these landforms and deposits. Flat, smooth topographies, as well as (low-angle) slope environments, correspond to microfabrics which lack microscopic shear-zone geometries and contain dropstones, angular-sediment clasts, large-shell fragments and slight sorting in sandy layers, which imply ice-shelf or open-water conditions present during deposition.

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Dickinson, William R. „Geological perspectives on the Monte Verde archeological site in Chile and pre-Clovis coastal migration in the Americas“. Quaternary Research 76, Nr. 2 (September 2011): 201–10. http://dx.doi.org/10.1016/j.yqres.2011.06.011.

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AbstractDiscovery of the Monte Verde archeological site in Chile overturned the previous consensus that the first Americans into the New World from Asia were the makers of Clovis projectile points, and rejuvenated the hypothesis that migration through the Americas occurred largely on portions of the Pacific continental shelf exposed by Pleistocene drawdown in eustatic sea level. The postulate of travel along a paleoshoreline now hidden underwater is an attractive means to posit pre-Clovis human movement southward from Beringia to Chile without leaving traces of migration onshore. Geologic analyses of the Pleistocene paleoenvironment at Monte Verde and of the morphology of the potential migration route along the continental shelf raise questions that have not been fully addressed. The periglacial setting of Monte Verde may call its antiquity into question and the narrowness of the Pacific continental shelf of the Americas makes it unlikely that people could travel the length of the Americas without impacting ground still onshore and no farther inland than Monte Verde itself. Geological perspectives on Monte Verde and coastal migration jointly suggest that the Clovis-first hypothesis for peopling the New World may have been abandoned prematurely.

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D’Agostini, Danielle P., Alex C. Bastos, Gilberto M. Amado-Filho, Claudia G. Vilela, Thaís C. S. Oliveira, Jody M. Webster und Rodrigo L. Moura. „Morphology and sedimentology of the shelf-upper slope transition in the Abrolhos continental shelf (east Brazilian margin)“. Geo-Marine Letters 39, Nr. 2 (06.03.2019): 117–34. http://dx.doi.org/10.1007/s00367-019-00562-6.

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Chimienti, Giovanni, Lucia Rizzo, Sara Kaleb, Annalisa Falace, Simonetta Fraschetti, Francesco De Giosa, Angelo Tursi, Enrico Barbone, Nicola Ungaro und Francesco Mastrototaro. „Rhodolith Beds Heterogeneity along the Apulian Continental Shelf (Mediterranean Sea)“. Journal of Marine Science and Engineering 8, Nr. 10 (19.10.2020): 813. http://dx.doi.org/10.3390/jmse8100813.

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Rhodolith beds represent a key habitat worldwide, from tropical to polar ecosystems. Despite this habitat is considered a hotspot of biodiversity, providing a suite of ecosystem goods and services, still scarce quantitative information is available thus far about rhodolith beds occurrence and ecological role, especially in the Mediterranean Sea. This study reports the composition and patterns of distribution of rhodolith assemblages found in four study areas along ca. 860 km of coast in the Central Mediterranean Sea. These rhodolith beds were studied for the first time and significant differences at all spatial scales have been highlighted, documenting the high variability of this habitat. Rhodolith species composition, morphology and distribution have been discussed considering the potential role of environmental factors in driving these patterns. The need for improving their protection is discussed to complement present conservation and management initiatives, particularly in the frame of the EU Marine Strategy Framework Directive.

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Linklater, Michelle, Timothy C. Ingleton, Michael A. Kinsela, Bradley D. Morris, Katie M. Allen, Michael D. Sutherland und David J. Hanslow. „Techniques for Classifying Seabed Morphology and Composition on a Subtropical-Temperate Continental Shelf“. Geosciences 9, Nr. 3 (22.03.2019): 141. http://dx.doi.org/10.3390/geosciences9030141.

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In 2017, the New South Wales (NSW) Office of Environment and Heritage (OEH) initiated a state-wide mapping program, SeaBed NSW, which systematically acquires high-resolution (2–5 m cell size) multibeam echosounder (MBES) and marine LiDAR data along more than 2000 km of the subtropical-to-temperate southeast Australian continental shelf. This program considerably expands upon existing efforts by OEH to date, which have mapped approximately 15% of NSW waters with these technologies. The delivery of high volumes of new data, together with the vast repository of existing data, highlights the need for a standardised, automated approach to classify seabed data. Here we present a methodological approach with new procedures to semi-automate the classification of high-resolution bathymetry and intensity (backscatter and reflectivity) data into a suite of data products including classifications of seabed morphology (landforms) and composition (substrates, habitats, geomorphology). These methodologies are applied to two case study areas representing newer (Wollongong, NSW) and older (South Solitary Islands, NSW) MBES datasets to assess the transferability of classification techniques across input data of varied quality. The suite of seabed classifications produced by this study provide fundamental baseline data on seabed shape, complexity, and composition which will inform regional risk assessments and provide insights into biodiversity and geodiversity.

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Durán, Ruth, Miquel Canals, José Luis Sanz, Galderic Lastras, David Amblas und Aaron Micallef. „Morphology and sediment dynamics of the northern Catalan continental shelf, northwestern Mediterranean Sea“. Geomorphology 204 (Januar 2014): 1–20. http://dx.doi.org/10.1016/j.geomorph.2012.10.004.

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Leonova, T. D., M. G. Valitov und O. V. Belous. „The South China sea continental slope morphology and its relation to the anomalous gravitational field“. Geomorphology RAS, Nr. 4 (08.11.2019): 67–76. http://dx.doi.org/10.31857/s0435-42812019467-76.

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The bottom topography of the studied area of the South China Sea is characterized by an uneven distribution of depths, their sharp variations and the presence of a large number of seamounts. As a result of the research conducted, bathymetric profiles, a bathymetric map and a scheme of Faye anomalies were compiled. Geomorphological zoning was conducted. Sections of bottom distinguished by morphology were identified: 1) weakly dissected slope, steep (angles up to 15) in the upper part and more gentle (57) to the bottom of the deep-water step, 2) slope eroded by fluvial processes, 3) stepped slope, 4) chains of mountains and flat-topped hills, 5) accumulative bottom of the deep-water plain. It was established that the gravitational field as a whole reflects the complex structure of the bottom, and the local forms of the underwater relief are expressed in Faye anomalies. For elevations, zones of positive anomalies of Faye are marked, and sections of canyon-like valleys were mapped by an intense negative anomaly of the gravitational field to -60 mGal. In the process of endogenous evolution of the region, the relief became more complex. The primary endogenous continental slope was almost everywhere transformed by exogenous processes. Within the shelf, the filling of the basin led to the unification of all its projections into a single raised base. A significant role in the formation of the modern relief was played by large-scale repeated sea regressions, as a result of which the formation of the sedimentary cover was interrupted by periods of its erosion with the formation of planation surfaces. The Late Pleistocene peak of the regression (1618 thousand years BP), which caused the complete drainage of the shelf areas of the region, caused the erosion of the shelf and the movement of coarse clastic material through submarine canyons and valleys.

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CUNHA, CARLO M., und LUIZ RICARDO L. SIMONE. „A new species of the genus Rapturella (Gastropoda: Acteonidae) from southeast Brazil“. Zootaxa 4521, Nr. 1 (13.11.2018): 125. http://dx.doi.org/10.11646/zootaxa.4521.1.7.

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Acteonidae d'Orbigny, 1843 is the largest family within the superfamily Acteonoidea (Bouchet et al. 2017) and includes small gastropods typical of infralittoral environments. Most acteonids living on the continental shelf or in deep water have been described on the basis of shell morphology alone (Simone 2006; Valdés 2008; Cunha 2011; Salvador & Cunha 2016), because little material with soft parts has been collected and examined. Consequently, little is known about the ecology of the species. Recently, many new species of the genus Acteon Montfort, 1810 have been described from tropical Southwest Pacific waters (Valdés 2008), suggesting that a high diversity of acteonid species may await discovery in other deep water environments, including those of Brazil.

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Distefano, Salvatore, Fabiano Gamberi, Niccolò Baldassini und Agata Di Stefano. „Quaternary Evolution of Coastal Plain in Response to Sea-Level Changes: Example from South-East Sicily (Southern Italy)“. Water 13, Nr. 11 (28.05.2021): 1524. http://dx.doi.org/10.3390/w13111524.

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During a cycle of sea-level variation, coastal environments develop in different position of the continental shelf following seaward and landward shift of the coastline. They vary widely in character, reflecting the wide range of process-regimes that are brought about during the different stages of sea-level variations. Within this scenario, the morphology of continental shelves, mainly resulting from the combined effect of tectonic activity and eustatism, plays an important role in controlling the features and the preservation of coastal environments. Coastal deposits formed along continental shelves in the past, during different stages of sea-level changes, consist of discontinuous and thin depositional bodies, thus their reconstruction can be best carried out through the interpretation of high-resolution seismic data. Such a research approach is adopted in the present study to investigate a portion of the continental shelf of the southernmost sector of SE Sicily, in the offshore of Marzamemi village (Syracuse). The interpretation of high-resolution “Sparker” profiles allowed us to reconstruct the evolution of alluvial and lagoonal environments, established on a substratum of Pliocene or more ancient marine deposits, with the detection of several seismic units and unconformity surfaces, which have been related to alternating sedimentation and erosional processes, depicting the sea-level change framework of glacial-interglacial phases, from the late Pleistocene onward.

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Gomes, Moab P., Helenice Vital, Francisco H. R. Bezerra, David L. de Castro und José W. de P. Macedo. „The interplay between structural inheritance and morphology in the Equatorial Continental Shelf of Brazil“. Marine Geology 355 (September 2014): 150–61. http://dx.doi.org/10.1016/j.margeo.2014.06.002.

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Ihenyen, A. E. „Western Nigerian continental shelf, morphology, sediment pattern and Holocene transgressional phases of the coastline“. Bulletin of the Geological Society of Malaysia 40 (30.07.1997): 241–47. http://dx.doi.org/10.7186/bgsm40199718.

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ΠΕΡΙΣΟΡΑΤΗΣ, Κ. „The Geological study of the sea bottom and subbotom and the recent research trends (with emphasis on the continental shelf area)“. Bulletin of the Geological Society of Greece 34, Nr. 6 (01.01.2002): 2149. http://dx.doi.org/10.12681/bgsg.16859.

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The systematic research of the sea bottom started axcually only in the 19th century with the research voyage of the British ship "CHALLENGER" but was particularly developed during the early 20th century. The Greek seas were geologically explored after 1950, with the research trip of the R/V Verna in 1954 in Korinthiakos Gulf. Since then a great number of research programs has been carried out in the Greek Seas both in the shelf and the deep sectors in which the Greek scientists have played a major role. The major factor in shaping the todays shelf morphology is sedimentation controlled mainly by the sea level changes during Quaternary. The shelf break in the Aegean and Ionian seas lies at a depth of 120m. to 160m. and is usually covered by relict sediments and locally by holocenic sediments, particularly at the deltaic areas. In low sea level stands many of the todays gulfs were subaerically exposed or constituted lakes of variable depth with or without outlets toward the open sea. During these stages coarse sediments were deposited mainly beyond the shelf break. During high sea level stages the coarse sediments were deposited on the shelf and the fine grained ones surpassing the self break were deposited in the deep areas. Theses changes in sediment texture are reflected in the deep sea seismic profiles as alternating opaque-transparent layers. Although the Greek area is characterized by high seismic and tectonic activity, tectonism and eustatic/isostatic factors played a considerably minor role in shaping the shelf morphology that of sea level changes. The study of the shelf area during the various sea level stands helped in locating occurrence of placer deposits in the Northern Aegean shelf and in recognizing the trans gressional layer as a suitable horizon for foundation of civil engineering projects. Except these, the shelf studies contributed important information to the basic geological knowledge. Examples from condribution to geoarchaeology to biogeography are cited. Regarding the future research trends in Marine Geology, these can be: The development of marine data (metadata) bases. The systematic use of multibean systems. The further development of digital processing of the seismic reflection records. The collection of data for the anticipating future climatic changes. The assessment of the eventual catastrophic events in the coastal zone. The recording in real time of the active sedimentation parameters.

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LAST, PETER, und WILLIAM J. RICHARDS. „Two new gurnards of the genus Pterygotrigla (Scorpaeniformes: Triglidae) from Australian seas“. Zootaxa 3195, Nr. 1 (16.02.2012): 39. http://dx.doi.org/10.11646/zootaxa.3195.1.2.

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In recent years there has been considerable research activity devoted to the triglid fauna of Australia, and included within this work has been an investigation of the genus Pterygotrigla. This fauna is considered to be amongst the most diverse of any region and multiple undescribed taxa occur in these seas. Two new species belonging to the subgenus Pterygotrigla are described from northern Australia. Pterygotrigla (Pterygotrigla) gomoni sp. nov. occurs in the eastern Indian Ocean on the upper continental slope off Western Australia, and P. (Pterygotrigla) saumarez sp. nov. occurs in the south-west Pacific on the outer continental shelf and upper slope off central and southern Queensland. These species differ markedly from each other in morphology, and are distinguished from other members of the subgenus by a combination of morphometrics, meristics, morphology of the head (in particular elements of its spination), shape and distribution of the dorsal-fin bucklers, and pectoral-fin coloration.

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Collins, Lindsay B., und Viviane Testa. „Quaternary development of resilient reefs on the subsiding kimberley continental margin, Northwest Australia“. Brazilian Journal of Oceanography 58, spe1 (2010): 67–77. http://dx.doi.org/10.1590/s1679-87592010000500007.

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The Kimberley region in remote northwest Australia has poorly known reef systems of two types; coastal fringing reefs and atoll-like shelf-edge reefs. As a major geomorphic feature (from 12ºS to 18ºS) situated along a subsiding continental margin, the shelf edge reefs are in a tropical realm with warm temperatures, relatively low salinity, clear low nutrient waters lacking sediment input, and Indo-West Pacific corals of moderate diversity. Seismic architecture of the Rowley Shoals reveals that differential pre-Holocene subsidence and relative elevation of the pre-Holocene substrate have controlled lagoon sediment infill and reef morphology, forming an evolutionary series reflecting differential accommodation in three otherwise similar reef systems. The Holocene core described for North Scott Reef confirms previous seismic interpretations, and provides a rare ocean-facing reef record. It demonstrates that the Indo-Pacific reef growth phase (RG111) developed during moderate rates of sea level rise of 10 mm/year from 11 to about 7-6.5 ka BP until sea level stabilization, filling the available 27 m of pre-Holocene accommodation. Despite the medium to high hydrodynamic energy imposed by the 4m tides, swell waves and cyclones the reef-building communities represent relatively low-wave energy settings due to their southeast facing and protection afforded by the proximity of the South Reef platform. This study demonstrates the resilience of reefs on the subsiding margin whilst linking Holocene reef morphology to the relative amount of pre-Holocene subsidence.

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Tarazona, Darwin Mateus, Jorge Prieto, William Murphy, Julian Naranjo Vesga, Daniel Rincon, Carlos Hernandez Munoz, Hernan Madero Pinzon, Anderson Mora Mora und Mateo Acuña-Uribe. „Submarine landslide susceptibility assessment along the southern convergent margin of the Colombian Caribbean“. Leading Edge 42, Nr. 5 (Mai 2023): 344–59. http://dx.doi.org/10.1190/tle42050344.1.

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Submarine landslides are a mixture of rock, sediment, and fluids moving downslope due to a slope's initial event of mechanical failure. Submarine landslides play a critical role in shaping the morphology of the seafloor and the transport of sediments from the continental shelf to the continental rise in the southern margin of the Colombian Caribbean. Two fundamental considerations can be highlighted: first, mass transport complexes produced by submarine landslides encompass significant portions of the stratigraphic record; second, these mass movements could affect underwater infrastructure. The mapping of the Southern Caribbean seafloor using 3D seismic surveys and multibeam bathymetry data in an area encompassing 59,471 km2 allowed the identification of 220 submarine landslides with areas ranging between 0.1 and 209 km2. Distinctive characteristics were found for submarine landslides associated with canyon walls, channel-levee systems, tectonically controlled ridges, and the continental shelf break. The analysis of the relationship between submarine landslides and seafloor morphological features made it possible to estimate a mass movement susceptibility map that suggests the following considerations: first, structural ridges and adjacent intraslope subbasins related to the South Caribbean Deformed Belt are more likely to be submarine landslide hazards; second, the continental shelf break and channelized systems produce a moderate submarine landslide hazard potential; and third, deep marine systems with a slope less than 5° show the lowest submarine landslide hazard potential. This work contributes to the understanding of submarine landslides in the study area through the presentation of conceptual diagrams that provide additional visual elements facilitating the level of abstraction necessary for visualizing bathymetric data. Likewise, the mass movement susceptibility map presented herein gives insights for future studies that seek to evaluate geohazards in the southern Colombian Caribbean margin.

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LARSEN, KIM, und RICHARD W. HEARD. „A new tanaidacean subfamily, Bathytanaidinae (Crustacea: Paratanaididae), from the Australian continental shelf and slope“. Zootaxa 19, Nr. 1 (20.12.2001): 1. http://dx.doi.org/10.11646/zootaxa.19.1.1.

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Four new species of the paratanaid genera Bathytanais Beddard and Pseudobathytanais KudinovaPasternak are described from Australia. Bathytanais culterformis and B. arenamans were found on the northwestern continental shelf off western Australia. Bathytanais fragilis and Pseudobathytanais gibberosus are described from the southeastern Australian continental slope. Bathytanais and Pseudobathytanais are placed in the new subfamily Bathytanaidinae, which represents a group of highly derived tanaidomorphs with uniquely modified long setulated setae on the antennule and antenna. The new subfamily is further characterized by having a well-developed, anteriorly directed, epistomal process. The distinctive morphology of the antennule and antennae indicate that members of the Bathytanaidinae have evolved as suspension or filter feeders. A key to the species within the Bathytanaidinae is presented. An unidentified tantulocarid crustacean parasite occurred on the pleotelson of two specimens of P. gibberosus, constituting the first host record on a member of the Paratanaididae.

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Fraser, Sarah B., und George R. Sedberry. „Reef Morphology and Invertebrate Distribution at Continental Shelf Edge Reefs in the South Atlantic Bight“. Southeastern Naturalist 7, Nr. 2 (Juni 2008): 191–206. http://dx.doi.org/10.1656/1528-7092(2008)7[191:rmaida]2.0.co;2.

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Christie, Frazer D. W., Robert G. Bingham, Noel Gourmelen, Eric J. Steig, Rosie R. Bisset, Hamish D. Pritchard, Kate Snow und Simon F. B. Tett. „Glacier change along West Antarctica's Marie Byrd Land Sector and links to inter-decadal atmosphere–ocean variability“. Cryosphere 12, Nr. 7 (26.07.2018): 2461–79. http://dx.doi.org/10.5194/tc-12-2461-2018.

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Abstract. Over the past 20 years satellite remote sensing has captured significant downwasting of glaciers that drain the West Antarctic Ice Sheet into the ocean, particularly across the Amundsen Sea Sector. Along the neighbouring Marie Byrd Land Sector, situated west of Thwaites Glacier to Ross Ice Shelf, glaciological change has been only sparsely monitored. Here, we use optical satellite imagery to track grounding-line migration along the Marie Byrd Land Sector between 2003 and 2015, and compare observed changes with ICESat and CryoSat-2-derived surface elevation and thickness change records. During the observational period, 33 % of the grounding line underwent retreat, with no significant advance recorded over the remainder of the ∼ 2200 km long coastline. The greatest retreat rates were observed along the 650 km-long Getz Ice Shelf, further west of which only minor retreat occurred. The relative glaciological stability west of Getz Ice Shelf can be attributed to a divergence of the Antarctic Circumpolar Current from the continental-shelf break at 135∘ W, coincident with a transition in the morphology of the continental shelf. Along Getz Ice Shelf, grounding-line retreat reduced by 68 % during the CryoSat-2 era relative to earlier observations. Climate reanalysis data imply that wind-driven upwelling of Circumpolar Deep Water would have been reduced during this later period, suggesting that the observed slowdown was a response to reduced oceanic forcing. However, lack of comprehensive oceanographic and bathymetric information proximal to Getz Ice Shelf's grounding zone make it difficult to assess the role of intrinsic glacier dynamics, or more complex ice-sheet–ocean interactions, in moderating this slowdown. Collectively, our findings underscore the importance of spatial and inter-decadal variability in atmosphere and ocean interactions in moderating glaciological change around Antarctica.

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Garcia, Marinês, und Clarisse Odebrecht. „Remarks on the morphology and distribution of some rare centric diatoms in southern Brazilian continental shelf and slope waters“. Brazilian Journal of Oceanography 60, Nr. 4 (Dezember 2012): 415–27. http://dx.doi.org/10.1590/s1679-87592012000400002.

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This paper provides information on the morphology and occurrence of extant diatoms of the family Asterolampraceae and Azpeitia species of the southernmost Brazilian continental shelf and slope waters in the Southwestern Atlantic Ocean (28 -34ºS), under the influence of Tropical, Subtropical, Subantarctic Waters, terrestrial discharges from La Plata River and Lagoa dos Patos lagoon. Plankton was sampled (20 µm net; vertical hauls) at the same 27 stations in winter 2005 and summer 2007. Among Asterolampraceae, Asteromphalus flabellatus was the most frequent species (57% of samples) observed mainly in winter samples (92%) in Subtropical Shelf Water but also under the influence of La Plata River plume (salinity <35). Lower frequencies were observed for Asterolampra marylandica, Asteromphalus elegans, Asteromphalus heptactis and Spatangidium arachne. Four species of Azpeitia were observed: A. barronii and A. neocrenulata for the first time in the South Atlantic Ocean while A. africana and A. nodulifer had already been registered in equatorial and southern areas of Brazil. All Azpeitia species were rare (19%) in offshore samples (100-200 m depth. Remarks on the morphology based on light and scanning electron microcopy observations are provided along with their distribution in the study area.

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Larter, Robert D., Kelly A. Hogan, Claus-Dieter Hillenbrand, James A. Smith, Christine L. Batchelor, Matthieu Cartigny, Alex J. Tate et al. „Subglacial hydrological control on flow of an Antarctic Peninsula palaeo-ice stream“. Cryosphere 13, Nr. 6 (05.06.2019): 1583–96. http://dx.doi.org/10.5194/tc-13-1583-2019.

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Abstract. Basal hydrological systems play an important role in controlling the dynamic behaviour of ice streams. Data showing their morphology and relationship to geological substrates beneath modern ice streams are, however, sparse and difficult to collect. We present new multibeam bathymetry data that make the Anvers-Hugo Trough west of the Antarctic Peninsula the most completely surveyed palaeo-ice stream pathway in Antarctica. The data reveal a diverse range of landforms, including streamlined features where there was fast flow in the palaeo-ice stream, channels eroded by flow of subglacial water, and compelling evidence of palaeo-ice stream shear margin locations. We interpret landforms as indicating that subglacial water availability played an important role in facilitating ice stream flow and controlling shear margin positions. Water was likely supplied to the ice stream bed episodically as a result of outbursts from a subglacial lake located in the Palmer Deep basin on the inner continental shelf. These interpretations have implications for controls on the onset of fast ice flow, the dynamic behaviour of palaeo-ice streams on the Antarctic continental shelf, and potentially also for behaviour of modern ice streams.

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Lavoie, Denis. „Diachronous tectonic collapse of the Ordovician continental margin, eastern Canada: comparison between the Quebec Reentrant and St. Lawrence Promontory“. Canadian Journal of Earth Sciences 31, Nr. 8 (01.08.1994): 1309–19. http://dx.doi.org/10.1139/e94-113.

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The Upper Ordovician Trenton Group of southern Quebec represents the last Taconian foreland basin carbonate unit in the Quebec Reentrant, prior to final collapse of Laurentia's continental margin and its burial under synorogenic flysch. The Trenton Group, either conformably or unconformably, overlies the Black River Group and is in turn conformably overlain by the Utica Shales. The tripartite Trenton carbonate unit records progressive deepening: (1) very shallow to shallow subtidal, (2) shallow to deep carbonate ramp, and (3) shallow to deep outer shelf. Regional facies distribution, lithotectonic elements, and thickness variations indicate that the Trenton shelf was dissected by extensional faults delineating blocks subsiding at various rates. This scenario compares favourably with Taconian foreland basin development in the Middle Ordovician Table Head Group at the St. Lawrence Promontory, Newfoundland. A similar stratigraphic succession and tectono-sedimentary history occurring 10–15 Ma earlier at the St. Lawrence Promontory than in the Quebec Reentrant argues for a primary tectonic control for the demise of carbonate sedimentation at the margin. The diachroneity in the foreland evolution can be related to the irregular morphology of the Laurentia continental margin.

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BARROSO, R., P. C. PAIVA und N. RANAURO. „Three new species of Aricidea (Acmira) (Annelida: Paraonidae) from the Continental Shelf of Eastern Brazil, Southwestern Atlantic“. Zootaxa 4838, Nr. 3 (27.08.2020): 415–26. http://dx.doi.org/10.11646/zootaxa.4838.3.6.

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Three new species of the Paraonidae genus Aricidea (Acmira) are described from the Southwestern Atlantic, East Brazilian Continental Shelf (from depths between 11 and 44 m) in the Espírito Santo Basin. The species Aricidea (Acmira) filamentosa sp. nov., Aricidea (Acmira) pearti sp. nov. and Aricidea (Acmira) bbkingi sp. nov. are clearly different from all known species in the genus through its chaetal morphology, number of branchiate chaetigers and shape of antenna. These three species were found in only a few sampling stations, geographically and bathymetrically restricted within a much wider sampled area.

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Cukur, Deniz, Gee-Soo Kong, Jong-Hwa Chun, Moo-Hee Kang, In-Kwon Um, Taekhyun Kwon, Samuel Y. Johnson und Kyong-O. Kim. „Morphology and genesis of giant seafloor depressions on the southeastern continental shelf of the Korean Peninsula“. Marine Geology 415 (September 2019): 105966. http://dx.doi.org/10.1016/j.margeo.2019.105966.

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Violante, R. A., C. M. Paterlini, S. I. Marcolini, I. P. Costa, J. L. Cavallotto, C. Laprida, W. Dragani et al. „Chapter 6 The Argentine continental shelf: morphology, sediments, processes and evolution since the Last Glacial Maximum“. Geological Society, London, Memoirs 41, Nr. 1 (2014): 55–68. http://dx.doi.org/10.1144/m41.6.

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Dowdeswell, Julian A., Christine L. Batchelor, Boris Dorschel, Toby J. Benham, Frazer D. W. Christie, Evelyn K. Dowdeswell, Aleksandr Montelli, Jan Erik Arndt und Catalina Gebhardt. „Sea-floor and sea-ice conditions in the western Weddell Sea, Antarctica, around the wreck of Sir Ernest Shackleton's Endurance“. Antarctic Science 32, Nr. 4 (08.04.2020): 301–13. http://dx.doi.org/10.1017/s0954102020000103.

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AbstractMarine-geophysical evidence on sea-floor morphology and shallow acoustic stratigraphy are used to examine the substrate around the location at which Sir Ernest Shackleton's ship Endurance sank in 1915 and on the continental slope-shelf sedimentary system above this site in the western Weddell Sea. Few signs of turbidity-current and mass-wasting activity are found near or upslope of the wreck site, and any such activity was probably linked to full-glacial higher-energy conditions when ice last advanced across the continental shelf. The wreck is well below the maximum depth of iceberg keels and will not have been damaged by ice-keel ploughing. The wreck has probably been draped by only a few centimetres of fine-grained sediment since it sank in 1915. Severe modern sea-ice conditions hamper access to the wreck site. Accessing and investigating the wreck of Endurance in the Weddell Sea therefore represents a significant challenge. An ice-breaking research vessel is required, and even this would not guarantee that the site could be reached. Heavy sea-ice cover at the wreck site, similar to that encountered by Agulhus II during the Weddell Sea Expedition 2019, would also make the launch and recovery of autonomous underwater vehicles and remotely operated vehicles deployed to investigate the Endurance wreck problematic.

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HALBERSTADT, ANNA RUTH W., LAUREN M. SIMKINS, JOHN B. ANDERSON, LINDSAY O. PROTHRO und PHILIP J. BART. „Characteristics of the deforming bed: till properties on the deglaciated Antarctic continental shelf“. Journal of Glaciology 64, Nr. 248 (29.11.2018): 1014–27. http://dx.doi.org/10.1017/jog.2018.92.

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ABSTRACTContemporary ice stream flow is directly linked to conditions at the ice/bed interface, yet this environment is logistically difficult to access. Instead, we investigate subglacial processes important for ice stream flow by studying tills on the deglaciated Antarctic continental shelf. We test currently-accepted hypotheses surrounding subglacial processes and till properties with a Ross Sea dataset. Till shear strengths indicate a continuum of simultaneous processes acting at the bed, rather than discrete ‘deformation’ and ‘lodgement’ end-members. We identify a threshold water content representing saturated pore spaces, leading to basal sliding and meltwater channelization. Based on observations of till properties relative to glacial landforms, we challenge the assumption that low shear strength is linked to intense deformation. Spatial variability in landform morphology reflects variability in deforming processes at the sub-ice stream scale and suggests a maximum deforming bed thickness of 2 m at the grounding line. Regional till properties generally correlate with seafloor geology and deglacial history; the western Ross Sea is characterized by higher and more variable shear strengths and water contents, while lower-shear strength till was preserved in the Eastern Basin. These observations inform till interpretation and provide context for deforming beds beneath the modern ice sheet and on glaciated continental shelves.

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Budillon, Francesca, Marco Firetto Carlino, Sara Innangi, Salvatore Passaro, Renato Tonielli, Fabio Trincardi und Mario Sprovieri. „The Anthropogenic Footprint of Physical Harm on the Seabed of Augusta Bay (Western Ionian Sea); A Geophysical Investigation“. Journal of Marine Science and Engineering 10, Nr. 11 (12.11.2022): 1737. http://dx.doi.org/10.3390/jmse10111737.

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Augusta Bay is an embayment of the Hyblean sector in south-eastern Sicily (Southern Italy) that faces the Ionian Sea and includes the Rada di Augusta, a wide littoral sector sheltered by breakwaters, which hosts intense harbor activities. Rada di Augusta and the adjacent Priolo embayment were listed in the National Remediation Plan (NRP) by the Italian Ministry of Environment, as they have suffered major anthropic impacts over the last seventy years. Indeed, extensive petrochemical and industrial activities, military and commercial maritime traffic, as well as agriculture and fishery activities, have resulted in a highly complex combination of impacts on the marine environment and seafloor. In this paper, we investigate the extent of human-driven physical impacts on the continental shelf, offshore of Rada di Augusta, by means of Multibeam echosounder, Side-Scan Sonar and Chirp Sonar profilers, as well as direct seabed samplings. At least seven categories of anthropogenic footprints, i.e., anchor grooves and scars, excavations, trawl marks, targets, dumping trails, isolated dumping and dumping cumuli, mark the recent human activities at the seafloor. The practice of dredge spoil disposal, possibly protracted for decades during the last century, has altered the seafloor morphology of the central continental shelf, by forming an up-to-9 m-thick hummocky deposit, with acoustic features noticeably different from those of any other shelf lithosome originated by natural processes. All available data were reported in an original thematic map of the seafloor features, offering an unprecedented opportunity to unravel sediment facies distribution and localization of anthropogenic disturbance. Finally, the shelf area was ranked, based on the coexistence of multiple stressors from human-driven physical harm, thus providing a semi-quantitative analysis of environmental damage classification in the area.

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Smith, Craig R., Laura J. Grange, David L. Honig, Lieven Naudts, Bruce Huber, Lionel Guidi und Eugene Domack. „A large population of king crabs in Palmer Deep on the west Antarctic Peninsula shelf and potential invasive impacts“. Proceedings of the Royal Society B: Biological Sciences 279, Nr. 1730 (07.09.2011): 1017–26. http://dx.doi.org/10.1098/rspb.2011.1496.

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Lithodid crabs (and other skeleton-crushing predators) may have been excluded from cold Antarctic continental shelf waters for more than 14 Myr. The west Antarctic Peninsula shelf is warming rapidly and has been hypothesized to be soon invaded by lithodids. A remotely operated vehicle survey in Palmer Deep, a basin 120 km onto the Antarctic shelf, revealed a large, reproductive population of lithodids, providing the first evidence that king crabs have crossed the Antarctic shelf. DNA sequencing and morphology indicate the lithodid is Neolithodes yaldwyni Ahyong & Dawson, previously reported only from Ross Sea waters. We estimate a N. yaldwyni population density of 10 600 km −2 and a population size of 1.55 × 10 6 in Palmer Deep, a density similar to lithodid populations of commercial interest around Alaska and South Georgia. The lithodid occurred at depths of more than 850 m and temperatures of more than 1.4°C in Palmer Deep, and was not found in extensive surveys of the colder shelf at depths of 430–725 m. Where N. yaldwyni occurred, crab traces were abundant, megafaunal diversity reduced and echinoderms absent, suggesting that the crabs have major ecological impacts. Antarctic Peninsula shelf waters are warming at approximately 0.01°C yr −1 ; if N. yaldwyni is currently limited by cold temperatures, it could spread up onto the shelf (400–600 m depths) within 1–2 decades. The Palmer Deep N. yaldwyni population provides an important model for the potential invasive impacts of crushing predators on vulnerable Antarctic shelf ecosystems.

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Gipp, Michael R. „Lift-off moraines: markers of last ice-flow directions on the Scotian Shelf“. Canadian Journal of Earth Sciences 37, Nr. 12 (01.12.2000): 1723–34. http://dx.doi.org/10.1139/e00-066.

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Lift-off moraines are acoustically incoherent, subparallel ridges observed on sidescan sonograms and high-resolution reflection seismic profiles on the southeastern continental margin of Canada. They are up to 3 m high, 2080 m wide, and are commonly overlain by stratified proglacial sediments. Although little is known about them, detailed study of high-resolution seismic profiles from the Emerald Basin and the LaHave Basin, on the Scotian Shelf, show that their height:width ratio varies with the sounderseabed separation, suggesting that the ridges may be narrower than they appear. Their morphology is similar to DeGeer moraines or cross-valley moraines, which form perpendicular to ice-flow direction. As their orientations can be estimated at the intersection of seismic lines, they can be used to estimate ice-flow directions. Since proglacial sediments are draped directly over top of them, they are assumed to record the direction of last ice flow. This directional data suggests that ice retreated not only northward (to Nova Scotia), but also toward local topographic highs on the continental shelf, which acted as anchoring points for ice rises around both the Emerald and LaHave Basins. This pattern of ice-flow directions suggests that ice flowed from the high ground of banks, converging into basin deeps, suggesting that small moraines within the basins are probably of interlobate origin.

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Brooke, Brendan P., Scott L. Nichol, Zhi Huang und Robin J. Beaman. „Palaeoshorelines on the Australian continental shelf: Morphology, sea-level relationship and applications to environmental management and archaeology“. Continental Shelf Research 134 (Februar 2017): 26–38. http://dx.doi.org/10.1016/j.csr.2016.12.012.

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Lantzsch, Hendrik, Till J. J. Hanebuth, Cristiano M. Chiessi, Tilmann Schwenk und Roberto A. Violante. „The high-supply, current-dominated continental margin of southeastern South America during the late Quaternary“. Quaternary Research 81, Nr. 2 (März 2014): 339–54. http://dx.doi.org/10.1016/j.yqres.2014.01.003.

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AbstractThe continental margin off the La Plata Estuary (SE South America) is characterized by high fluvial sediment supply and strong ocean currents. High-resolution sediment-acoustic data combined with sedimentary facies analysis, AMS-14C ages, and neodymium isotopic data allowed us to reconstruct late Quaternary sedimentary dynamics in relation to the two major sediment sources, the La Plata Estuary and the Argentine margin. Sediments from these two provinces show completely different dispersal patterns. We show that the northward-trending La Plata paleo-valley was the sole transit path for the huge volumes of fluvial material during lower sea levels. In contrast, material from the Argentine margin sector was transported northwards by the strong current system. Despite the large sediment volumes supplied by both sources, wide parts of the shelf were characterized by either persistent non-deposition or local short-term depocenter formation. The location and formation history of these depocenters were primarily controlled by the interplay of sea level with current strength and local morphology. The high sediment supply was of secondary importance to the stratigraphic construction, though locally resulting in high sedimentation rates. Thus, the shelf system off the La Plata Estuary can be considered as a hydrodynamic-controlled end-member.

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Klotsko, Shannon, und Neal Driscoll. „Geomorphological and stratigraphic evidence along the northeastern U.S. margin for Laurentide glacial lake outburst floods during the MIS 2 deglaciation“. Quaternary Research 90, Nr. 1 (17.05.2018): 139–52. http://dx.doi.org/10.1017/qua.2018.32.

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AbstractBlock Island Sound (BIS), in southern New England, was occupied by a glacial meltwater lake (Lake BIS) during the MIS 2 deglaciation. New CHIRP seismic data, swath bathymetry, and legacy seismic profiles from BIS provide important insights and constraints on the morphologic evolution of a glaciated margin from the last glacial maximum to present. Interpretation of seismic data revealed four well-defined sediment units: acoustic basement, glaciolacustrine varved sediments, a lag deposit, and Holocene sediment. The morphology and architecture of the sedimentary units suggest that Lake BIS drained quickly, followed by the catastrophic drainage of glacial Lake Connecticut through BIS (Lake Connecticut occupied present-day Long Island Sound). The draining waters carved depressions ~100 m deep in the floor of BIS and the region between the lakes. The waters also carved Block Island Valley, which extends across the continental shelf. Continued existence of the depressions and valley suggests a rapid transgression over these water depths and limited sediment supply. Our results show the significant impact of glacial lake outburst floods, even during a sea level transgression, and may help explain morphology observed along other glaciated margins.

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Munnelly, Ryan T., David B. Reeves, Edward J. Chesney und Donald M. Baltz. „Summertime hydrography of the nearshore Louisiana Continental Shelf: Effects of riverine outflow, shelf morphology, and the presence of sand shoals on water quality“. Continental Shelf Research 179 (Mai 2019): 18–36. http://dx.doi.org/10.1016/j.csr.2019.04.002.

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LAST, PETER R., und JUSTIN A. CHIDLOW. „Two new wobbegong sharks, Orectolobus floridus sp. nov. and O. parvimaculatus sp. nov. (Orectolobiformes: Orectolobidae), from southwestern Australia“. Zootaxa 1673, Nr. 1 (04.01.2008): 49. http://dx.doi.org/10.11646/zootaxa.1673.1.2.

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Two new Orectolobus species, collected from the continental shelf off southwestern Australia as bycatch of a regional shark fishery, are described and figured. Orectolobus floridus sp. nov., which has a striking colour pattern of yellowish brown bands, blotches, spots and reticulations, occurs between Geraldton and Augusta at depths of 42–85 m. Orectolobus parvimaculatus sp. nov., another small, colourful wobbegong shark, which is sympatric with O. floridus and three other congeners, has been confused with a larger, more widespread wobbegong, O. maculatus. Orectolobus parvimaculatus occurs between Green Head and Mandurah at depths of 9–108 m. The new species differ from other Orectolobus species and each other by a combination of colour, morphology, body measurements and meristics.

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CORRÊA, IRAN CARLOS STALLIVIERE. „Aplicação do Diagrama de Pejrup na Interpretação da Sedimentação e da Dinâmica do Estuário da Baía de Marajó-PA“. Pesquisas em Geociências 32, Nr. 2 (31.12.2005): 109. http://dx.doi.org/10.22456/1807-9806.19551.

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From statistical parameters of the bottom morphology and of the application of the diagram proposed by Pejrup(1988) it was possible to characterize the dynamic and sedimentary processes that occur in the estuary of the Marajó bay. The sediments that recover the bottom of the studied area are formed by medium to very fine sands that grade to coarse to fine silt in direction to the continental shelf. The hydrodynamic of the area is dominated by the tidal and fluvial currents as well, partly due the action of winds which influence these currents. These factors associated with the estuarine circulation, are responsible for the transport, redistribution and deposition of the sediments in the study area.

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Vital, Helenice, Samia F. Lima Furtado und Moab Praxedes Gomes. „Response of the Apodi-Mossoró estuary-incised valley system (NE Brazil) to sea-level fluctuations“. Brazilian Journal of Oceanography 58, spe2 (2010): 13–24. http://dx.doi.org/10.1590/s1679-87592010000600003.

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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.

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Williams, Alan, und Nicholas J. Bax. „Delineating fish-habitat associations for spatially based management: an example from the south-eastern Australian continental shelf“. Marine and Freshwater Research 52, Nr. 4 (2001): 513. http://dx.doi.org/10.1071/mf00017.

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A multi-scale, multi-gear survey identified the spatial structure and compositions of fish communities from a range of seabed types on the south-eastern Australian continental shelf (25 m to ~200 m depth). Most communities are species-rich and contain many shared species. Multivariate analysis of distributions of 201 fishes showed communities to be correlated with depth, latitude and seabed type;correlation with hydrodynamic climate is suggested by patterns in morphology. Depth-related patterns occurred on soft-sediment and hard substrata; strong latitudinal (south-west/north-east)patterns identify the area as a faunal transition zone with a major faunal disjunction extending across the shelf. Community patterns were overlaid on distributions of substrata to produce a biophysical map. This mapping process is discussed in the context of spatial management:the ecologically significant scale at which to map habitat features and definition of management units for ecosystem-based management. A hierarchy of scaled ecological units is being developed for Australia’s National Representative System of Marine Protected Areas (NRSMPA);given the scope of the NRSMPA initiative, surrogate measures of community structure will be required. Maps of substrata and topography, interpreted in the context of the broader depth and latitudinal community structure and as modified by hydrography, may provide one useful surrogate.

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Garcia, Marinês, und Clarisse Odebrecht. „Morphology and ecology of the planktonic diatom Palmerina hardmaniana (Greville) Hasle in southern Brazil“. Biota Neotropica 8, Nr. 2 (Juni 2008): 85–90. http://dx.doi.org/10.1590/s1676-06032008000200009.

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The diatom Palmerina hardmaniana (Greville) Hasle presents a wide geographical distribution in neritic tropical and subtropical regions. In the present work we analyzed plankton samples collected monthly between 1995 and 2007 at the surf zone of Cassino Beach, RS (32° 12' S and 52° 10' W), and in winter 2005 and summer 2007 at the continental shelf and slope in southern Brazil, Santa Marta Grande Cape, SC and Albardão-Chuí, RS regions (28° 23'-33° 07' S and 48° 41'-52° 26' W). We present the detailed morphological description of P. hardmaniana, and the first study including electron scanning microscope observations for material from the southwestern Atlantic Ocean. The morphometric data confirm the identity of the species in all its ultra-structural details. Palmerina hardmaniana was only observed in summer-autumn months with low cell density (< 500 cells.L-1) at both Cassino Beach surf zone and coastal shelf stations. The warm water temperature (18-29 °C) indicates the most probable origin of its inoculum are tropical/subtropical regions. Salinities of 23-36 and the relatively high silicate content indicate the importance of the terrestrial discharge during occasions when P. hardmaniana was observed, probably with influence on the nutrient availability. We emphasize that the species was not cited previously for Argentinean and Uruguayan waters and suggest that the southern Brazilian region is close to the southern geographical distribution limit of Palmerina hardmaniana in the southwestern Atlantic Ocean.

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Goff, John A., Daniel L. Orange, Larry A. Mayer und John E. Hughes Clarke. „Detailed investigation of continental shelf morphology using a high-resolution swath sonar survey: the Eel margin, northern California“. Marine Geology 154, Nr. 1-4 (Februar 1999): 255–69. http://dx.doi.org/10.1016/s0025-3227(98)00117-0.

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Schaaf, André. „Sea level changes, continental shelf morphology, and global paleoecological constraints in the shallow benthic realm: a theoretical approach“. Palaeogeography, Palaeoclimatology, Palaeoecology 121, Nr. 3-4 (Mai 1996): 259–71. http://dx.doi.org/10.1016/0031-0182(95)00085-2.

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Völker, David, Jacob Geersen, Eduardo Contreras-Reyes, Javier Sellanes, Silvio Pantoja, Wolfgang Rabbel, Martin Thorwart, Christian Reichert, Martin Block und Wilhelm Reimer Weinrebe. „Morphology and geology of the continental shelf and upper slope of southern Central Chile (33°S–43°S)“. International Journal of Earth Sciences 103, Nr. 7 (10.06.2012): 1765–87. http://dx.doi.org/10.1007/s00531-012-0795-y.

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Micallef, Aaron, Aggeliki Georgiopoulou, Andrew Green und Vittorio Maselli. „Impact of sea-level fluctuations on the sedimentation patterns of the SE African margin: implications for slope instability“. Geological Society, London, Special Publications 500, Nr. 1 (19.12.2019): 267–76. http://dx.doi.org/10.1144/sp500-2019-172.

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AbstractThe sheared-passive margin offshore Durban (South Africa) is characterized by a narrow continental shelf and steep slope hosting numerous submarine canyons. Supply of sediment to the margin is predominantly terrigenous, dominated by discharge from several short but fast-flowing rivers. International Ocean Discovery Program Expedition 361 provides a unique opportunity to investigate the role of sea-level fluctuations on the sedimentation patterns and slope instability along the South African margin. We analysed >300 sediment samples and downcore variations in P-wave, magnetic susceptibility, bioturbation intensity and bulk density from site U1474, as well as regional seismic reflection profiles to: (1) document an increase in sand input since the Mid-Pliocene; (2) associate this change to a drop in sea-level and extension of subaerial drainage systems towards the shelf-edge; (3) demonstrate that slope instability has played a key role in the evolution of the South Africa margin facing the Natal Valley. Furthermore, we highlight how the widespread occurrence of failure events reflects the tectonic control on the morphology of the shelf and slope, as well as bottom-current scour and instability of fan complexes. This information is important to improve hazard assessment in a populated coastal region with growing offshore hydrocarbon activities.

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Casalbore, Daniele, Romano Clementucci, Alessandro Bosman, Francesco Latino Chiocci, Eleonora Martorelli und Domenico Ridente. „Widespread mass-wasting processes off NE Sicily (Italy): insights from morpho-bathymetric analysis“. Geological Society, London, Special Publications 500, Nr. 1 (2020): 393–403. http://dx.doi.org/10.1144/sp500-2019-195.

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AbstractThe NE Sicilian continental margin is largely affected by canyons and related landslide scars. Two main types of submarine canyons are recognizable: the first type carves the shelf up to depths <20 m, a few hundred metres from the coast, acting as a main collector for sediments transported by hyperpycnal flows and/or littoral drift. These canyons mostly have a V-shaped cross-section and are characterized by a strong axial incision, where a network of dendritic gullies carving the canyon flanks converges. The second type of canyon occurs where the shelf is wider, hindering the direct connection between the subaerial and submarine drainage system. This setting exhibits canyon heads mostly confined to the shelf break, characterized by a weaker axial incision of the canyon and U-shaped cross-section. A total of 280 landslide scars are recognized in the study area and these are divided into three groups according to their morphology and location. A morphometric analysis of these scars is performed to investigate which parameters might be key factors in controlling instability processes and how they correlate with each other. We also try to assess the possible tsunamigenic potential associated with these landslide events by coupling the morphometric analysis with semi-empirical relationships available in the literature.

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