Lateglacial–Holocene shoreface progradation offshore eastern Scotland: a response to climatic and coastal hydrographic change
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Seismic facies, provenance and marine faunal associations of a nearshore prograding sediment wedge offshore eastern Scotland are studied to investigate environmental changes in the adjacent North Sea during Lateglacial–Holocene time. The sediments form part of the St. Andrews Bay Member (Forth Formation), which is divided into four lithozones (L1–L4) that represent distinct pulses of sedimentation during the sequential growth of the sediment wedge. Radiocarbon dates, combined with the local curve of relative sea level change, indicate that progradation was initiated as a fluvio‐deltaic deposit (L1) during the Younger Dryas Stadial. Further construction of the sediment package took place during the mid‐ to late Holocene by sublittoral tidal processes that deposited three discrete, highstand shoreface wedges (L2–L4), which display both progradation and longshore migration (to the NE), and may have experienced episodic brackish marine conditions. A depositional cyclicity of about 1000 years is proposed for lithozones L2–L4, separated by hiatuses of 1000–2000 years. We tentatively suggest that the Holocene development of the prograding wedge offshore eastern Scotland was a response to phases of strong westerly winds driving an enhanced influx of Atlantic Water into the North Sea. A concomitant increase in rainfall may account for the freshening of the coastal zone at this time. However, correlation with the recently postulated global periods of Holocene rapid climate change remains unclear.Keywords:
Progradation
Longshore drift
Marine transgression
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Evolution and environmental changes in the coastal plain of the headwater of Rio de la Plata. The coastal plains and surrounding areas in the south of Entre Rios Province together with the Parana delta represent the innermost environments of the Rio de la Plata that were affected by the late Pleistocene-Holocene post-glacial transgression. Thus, they evolved in the context of the evolution of the entire Rio de La Plata as a result of the combined effect of relative sea-level rise and fall, the coastal dynamic in the former littoral environments, climatic changes and substrate topography. The sedimentary record consists of a sequence of estuarine deposits, resulting from migration of a muddy depocentre during the transgression, underlying deposits representing beach-ridges, plains, dunes, low-energy beaches and deltas that evolved during the regressive event. These sediments respectively constitute two system tracts, transgressive and highstand, which are part of the sequences extended all along the entire La Plata river. There were three evolutionary stages. The first corresponds to the transition from transgression to highstand during times of higher temperature and humidity than at present, when the estuarine depocenter that had previously invaded the La Plata river reached its innermost position; minor deltas developed at the mouths of small rivers and beach ridges systems began to form. The second represents the first part of the highstand when drier climatic conditions prevailed, resulting in the interruption of progradation of small deltas and replacement by estuarine beaches formed by littoral drift and formation of dunes. The last stage elapsed from the moment when climatic conditions became more humid as the present conditions developed, such that an increase in water supply from the Parana river induced the formation of the Parana delta and the consequent isolation of the former innermost estuarine and beach-ridges environments. Regional correlations supported by radiocarbon dating reveal a synchronism between geomorphological events and features in the study area and in the southern margin of the Rio de La Plata.
Marine transgression
Progradation
Transgressive
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At the end of the last glacial period, a major marine transgression inundated the entire Persian Gulf. The precise position of the coastline with time has been the subject of several alternate interpretations. Utilizing sea level curves, shallow well data, sediment loads, satellite imagery, geomorphology, archeologic information, and historical data; the transgression and subsequent delta progradation at the head of the Persian Gulf can be delineated. The maximum transgression, at about 6000 B.P., extended about 400 km inland from the present shoreline. After 6000 B.P., the Shatt-al-Arab Delta prograded southward to its current position. Previous uncertainty about the extent of innundation and sedimentation in this archaeologically important area is, in part, the result of assymetric infilling of the embayment by large quantities of sediment from the Karun-Karkheh-Jarrahi River system. This portion of the delta prograded rapidly to the south, isolating a large portion of the embayment from the rest of the Gulf. The Hawzr marshes of today are the remnant of the freshwater lake(s) that formed in this fashion. The impact of these events on our knowledge of early human occupation and the development of civilization in the Tigris-Euphrates valley, is profound.
Marine transgression
Progradation
River delta
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Abstract The Holocene marine transgression in the Aegean Sea area has significantly impacted prehistoric societies. Toumba Gona is a tell site located at the mouth of the Anthemous River, east of Thessaloniki Bay. According to earlier research, the site should be dated at most to the late stage of the Early Bronze Age. Geoarchaeological research by means of electrical resistivity tomography, vibra‐coring, sedimentological analysis, and radiocarbon dating shows, however, that the direct proximity of the site witnessed the maximum marine transgression around 3000–2500 BC and the human habitation phase before the 3rd millennium BC, before the transgression. The coastline began to recede due to the delta progradation, which resulted in the formation of extensive marshes to the south of the Toumba. The increased fluvial activity since the end of the 4th millennium BC is relatable with the progradation of the Anthemous River's bay head delta. Human occupation was recorded before and after the marine transgression thus suggesting human persistence in the coastline environment.
Marine transgression
Progradation
Geoarchaeology
Chalcolithic
River delta
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Progradation
Longshore drift
Beach morphodynamics
Sedimentary budget
River delta
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ABSTRACT One of the most successful ways of classifying coastal environments has been to employ the dominant coastal process variables as discriminating parameters. This approach has been previously applied to deltas and continental shelves using the three parameters of waves, tides and rivers and to tidal inlets using only waves and tides. We suggest that a three parameter triangular classification can be extended to all coastal environments and enables a division into the primary categories of deltas, estuaries, barriers and tidal flats. Although combinations of coastal processes may remain constant through time on any coast, the coast itself undergoes continuous evolution. This necessitates the inclusion of time as a fourth parameter to satisfy an evolutionary coastal classification. If we adopt a sequence stratigraphic view of coastal evolution, then we may place most coastal sediments within either the transgressive or highstand systems tracts, undergoing either progradation (regression) or flooding (transgression). If we assume that all temporal evolution between sedimentary environments within the coastal system takes place during either a regression or transgression then we can substitute regression/transgression for time as the fourth parameter. Using this approach we see that all environments may occur in the general case but that at times of (maximum) flooding, estuaries predominate and that as sediment continues to be supplied during progradation, deltas, barriers and tidal flats expand at the expense of estuaries. At any one time, each depositional environment may be further subdivided using wave, tide and river process domination.
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Marine transgression
Progradation
Margin (machine learning)
Continental Margin
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BOREAS Anundsen, K. 1978 03 01: Marine transgression in Younger Dryas in Norway. Boreas, Vol. 7, pp. 49–60. Oslo. ISSN 0300–9483. The lithostratigraphy and biostratigraphy of sediment cores from two basins in southwestern Norway have been studied and radiocarbon dated. The diatom and the Hystrix content indicates a marine Younger Dryas transgression that reached its maximum level at the transition Younger Dryas/Preboreal Chronozone. No Allerød transgression to the same altitude can be demonstrated, and the suggested Allerød transgression at Bømlo (Faegri 1944) is most likely of Younger Dryas age, too.
Marine transgression
Preboreal
Allerød oscillation
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