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Beach Deposits (beach + deposit)
Selected AbstractsThe Late Weichselian sea level history of the Kullen Peninsula in northwest Skåne, southern SwedenBOREAS, Issue 2 2001PER SANDGREN The Kullen Peninsula in northwest Skåne, at the time of the Weichselian deglaciation an island surrounded by the Kattegat Sea, is the earliest known deglaciated area in Sweden. Sediment stratigraphic and mineral magnetic properties, combined with radiocarbon dating, were used to determine and date the isolation of present-day lake basins from the sea. Significant environmental changes, which reflect the isolations, are supported by previously published palaeoecological data and cannot be related to climate changes. Basins situated above the marine limit (ML) have short (in the order of centimetres) minerogenic sequences that are magnetically characterized by low concentrations of detrital magnetite. In contrast, the pre-isolation sediments in basins below the ML, especially those deposited in sheltered positions in the landscape, have thick sequences (in the order of metres) of authigenic greigite-bearing sediments. Age determinations of the isolation level are based on the AMS radiocarbon dating of terrestrial plant macrofossil remains and previously published pollen stratigraphical investigations. Supported by the upper level of a sandy beach deposit preserved on the generally steep till covered slopes, the marine limit can be determined to 88,89 m a.s.l., which developed at the regional deglaciation c. 17000 calendar years ago. The results indicate that the deglaciation shoreline level remained fairly constant, relative to the sea level, for c. 1000 years and was followed by a gentle regression. The presented shoreline displacement curve from the Kullen Peninsula extends c. 1000 calendar years further back in time than any previously published records from the Swedish west coast. [source] Stratigraphic and Morphologic Constraints on the Weichselian Glacial History of Northern Prins Karls Forland, Western SvalbardGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 4 2000Torbjörn Andersson Uncertainty remains if ice,free marginal areas existed on the west coast of Svalbard during the Late Weichselian. Field mapping and correlation to well dated raised beach sequences on nearby Brøggerhalvøya reveal the existence of two generations of raised beach deposits on northern Prins Karls Forland. Distinct beach ridges rise up to the inferred Late Weichselian marine limit at 18 m a.s.l. Discontinuous pre,Late Weichselian beach deposits rise from the Late Weichselian marine limit up to approximately 60 m a.s.l. Expansion of local glaciers during the Late Weichselian is indicated by the limited distribution of a till that overlies parts of the older beach sequence. Stratigraphic data and chronological control indicate deposition in a shallow marine environment before 50 ka bp. Correlation to stratigraphic sites on western Svalbard suggests deposition at c. 70 ±10 ka. Glaciotectonic structures disclose expansion of local glaciers into the For,landsundet basin during stage 4 or late stage 5 high relative sea level. Palaeotemperature estimates derived from amino acid ratios indicate that during the time interval c. 70 to 10 ka the area was exposed to cold subaerial temperatures with low rates of racemization. Pedogenesis and frost,shattered clasts at the contact between c. 70 ka deposits and Holocene deposits further indicate a prolonged period of subaerial polar desert conditions during this time interval. The evidence suggests that the Barents Sea ice sheet did not extend across northern Prins Karls Forland during the Weichselian. It is inferred that during the Late Weichselian, ice was drained throughout the major fjords on the west coast of Svalbard and that relatively large marginal areas experienced polar desert conditions and minor expansions of local glaciers. [source] Millennium-scale recurrent uplift inferred from beach deposits bordering the eastern Nankai Trough, Omaezaki area, central JapanISLAND ARC, Issue 3 2010Osamu Fujiwara Abstract A flight of Holocene marine terraces on the southwestern coast of Cape Omaezaki of central Japan provides evidence of recurrent millennium-scale uplift events. We reconstructed the uplift history of these terraces by using facies analysis of drill core and geoslicer samples, environmental analysis of trace fossils, and 14C age determinations. Coastal uplift can be identified by the displacement of beach deposits such as foreshore deposits, which represent the intertidal swash zone of a wave-dominated sandy coast. Three levels of former beach deposits facing the Nankai Trough were identified near the coast in the Omaezaki area. The highest of these, dated at about 3020,2880 BC, records a maximum of 2.2,2.7 m of emergence. The middle beach surface, of minimum age 370,190 BC, shows 1.6,2.8 m of emergence. The lowest beach surface, which is older than 1300,1370 AD, records 0.4,1.6 m of emergence. Our analysis of vertical crustal deformation data during the Holocene in this region suggests that rapid and strong uplift was restricted to the southwestern coast of the Omaezaki area and was probably caused by high-angle thrusting on subsidiary faults branching from the underlying plate boundary megathrust. [source] Holocene uplift rates and historical rapid sea-level changes at the Gargano promontory, ItalyJOURNAL OF QUATERNARY SCIENCE, Issue 5-6 2002Giuseppe Mastronuzzi Abstract This paper uses a combination of geomorphological and radiometric data from the northern coast of the Gargano promontory (comprising the Fortore River coastal plain and Punta delle Pietre Nere) to reconstruct Holocene uplift rates. The coastal plain consists of a sandy progradational beach sequence that extends seawards from the base of a relict cliff. This cliff probably marks the maximum position reached by the Holocene transgression. Altimetric data compared with the age of beach deposits and the available eustatic sea-level curves indicate an average Holocene uplift rate of 1.5 mm yr,1. A similar uplift rate has been estimated by dating a bioherm constituted of calcareous algae, Vermetids and subordinately by Cladocora caespitosa (L.), which crops out in the locality of Punta delle Pietre Nere. This deposit, which was previously assigned an interglacial age, yielded a mid-Holocene age by means of Th/U and 14C age determinations. Our observations also reveal evidence for coseismic deformation along the northern coast of the Gargano promontory during the last millennium. Vertical displacements of >0.5 m have affected the Punta delle Pietre Nere coastal block, and were preceded by periods of slow coastal subsidence, which increased rapidly shortly before a major earthquake. Copyright © 2002 John Wiley & Sons, Ltd. [source] Storegga tsunami sand in peat below the Tapes beach ridge at Harøy, western Norway, and its possible relation to an early Stone Age settlementBOREAS, Issue 3 2003STEIN BONDEVIK One of the early problems with the Storegga tsunami deposit was how to distinguish it from deposits of the midHolocene (Tapes) transgression. An excavation on Harøy, an island on the outermost western coast of Norway, shows a distinct, clean sand bed embedded in peat and clearly separated from the overlying Tapes beach deposits. This sand bed continues in the peat landwards of the beach ridge for at least 60 m. Radiocarbon dates of the peat show that the sand was deposited some time between 6900 and 7700 yr BP. The sedimentary structures of the bed, the 14C dates, and the fact that this is the only sand bed in the peat, suggest that the sand bed was deposited by a short-lived event, the Storegga tsunami. On the neighbouring island, Fjørtoft, a Stone Age settlement, dated to 7500 yr BP, was discovered in the early 1970s. The settlement was found underneath a sand bed that later had been covered by the Tapes beach ridge deposits. When discovered, the sand covering the settlement was inferred as eolian sand. However, this investigation shows that the Storegga tsunami deposited a widespread sand bed on the land surface around this time with a similar grain size distribution to eolian sand. It is therefore suggested that the sand bed covering this settlement was deposited from the Storegga tsunami. Both the stratigraphy and 14C dates demonstrate that the Tapes transgression maximum was reached well after the Storegga tsunami on Harøy, between 6500 and 6100 yr BP. [source] | |||||||||||||