Search

Crete is located in the collision zone of tectonic plates; therefore, the island coast was often shaped due to tectonic phenomena. In 365 AD, a major earthquake caused the uplift of the coast of western Crete by a few metres. It means that the modern beaches of this part of the island are fragments of the former seabed with its littoral deposits. Some of these deposits are affected by wind activity. The article aims to answer the question, did wind transport lasting more than 1600 years give the marine deposits the features of aeolian deposits? Grain size and mineral composition were determined for samples from seven research sites in western Crete. Deposits representing three sedimentary environments were examined – high-energy beach, aeolian, and beach with permanent or periodic fluvial supply. Quartz abrasion was established using the morphoscopic method. In the 0.8–1.0 mm fraction, less resistant carbonate minerals dominate (on average, 77%), while the content of more resistant quartz is low (on average, 18%). It means most deposits are relatively young and were briefly in the range of aeolian processes. Coastal deposits are dominated by moderately rounded and mat grains EM/RM, on average 79%. The content of very well-rounded and mat grains RM is low, on average 18%. Multiple predominances of EM/RM grains in relation to RM grains indicate short-term aeolian transport. It can be concluded that the degree of aeolisation of coastal deposits by wind activity from 365 AD to the present is weak, at most moderate.

The Itapeva dunefield is an active aeolian transgressive dunefield system and an important conservation area (PEVA State Park) in Torres-RS, Brazil. It is cataloged as a geosite and contains geoforms of scientific value for studying the sedimentary environments and paleoclimates of southern Brazil. It stands out for its esthetic, cultural, and recreational value for the development of tourism. However, the use and occupation of its surroundings developed rapidly, and the environmental problems associated with these changes make it desirable to apply the principles of coastal management with geoconservation to the region. This study characterizes the geoforms and analyzes how they have changed over time, in addition to describing some of the challenges for the geoconservation of the area. A geomorphological analysis was performed in this study, focusing on the identification and characterization of aeolian landforms and landform units present in the Itapeva dunefield. Recent satellite imagery, field observations, and photographs were used to conduct this research. The results show that the main aeolian depositional units present in the Itapeva dunefield are reversing transverse dunes, U-shaped sub-parabolic dunes, precipitation ridges, nebkhas, deflation plains, vegetated transgressive sand sheets, and foredunes. Erosional features such as blowouts occur mainly in the foredune area and/or are associated with nebkhas/remnant knobs. Understanding the importance of geoconservation within coastal management can be an important step toward the preservation of the few sectors comprising dunefields in Brazil. To benefit the Park’s sustainable development, it is prudent to promote geodiversity, geoconservation, and geotourism, incorporating these principles into coastal management. [ABSTRACT FROM AUTHOR]

• Raised beach is preserved at 3.3–5.3 m amsl in the upper Gulf of Thailand. • C14 and OSL age-dating suggest formation between 3.5–4.0 ka BP. • Provides evidence for Late Holocene local relative sea level (RSL) position. • Extends understanding of geographical variations in RSL across Southeast Asia. Few constructional features of coastal geomorphology have been investigated at the northernmost extremity of the Gulf of Thailand (GoT), with a view to establishing the position (height) of local relative sea level (RSL) during the marine regression following the regional mid-Holocene highstand (MHH) that occurred at approximately 6.5 ka BP. Here, the work investigates a 2 m thick exposure of marine gravels on the coast of Ko Khang Khao islet in the eastern Bay of Bangkok. At an elevation of 3.3–5.3 m above modern sea level, the sequence is interpreted to represent a Holocene raised beach. The unlithified sediments comprise rounded quartz and mylonite pebbles and cobbles, oriented predominantly NE–SW, supported by fossiliferous sands that are rich in marine shells, coral fragments and occasional terrestrial gastropods. The juxtaposition of the marine and non-marine gastropoda of contemporaneous ages makes a compelling story for a coastal storm deposit, thrown up either by a winter monsoon storm, or by a palaeotyphoon that managed to penetrate the upper Gulf. Overlapping results of C14 and OSL age-dating of shell material and mineral sands suggest the raised (storm) beach formed between 3.5 and 4.0 ka BP, i.e. ∼ 2.5–3.0 ka after the MHH peak, at a height of ∼ 1.3–3.3 m above the local RSL position at that time (according to glacial isostatic adjustment modelling). Given the otherwise paucity of data from the upper GoT, the Ko Khang Khao raised beach provides new information that expands our current understanding of geographical variations in RSL across Southeast Asia during the Late Holocene. [ABSTRACT FROM AUTHOR]

ABSTRACT: Establishing an accurate chronology for coastal sediment profiles using radiocarbon dating has been a challenging task for scientists around the world. In this study, we present a step-by-step procedure of an optimized pre-treatment method to remove roots, shell hashes, and other contaminants from organic-rich bulk sediments for radiocarbon dating. This procedure first applies loss-on-ignition analysis throughout the sediment profile to locate the ideal sampling intervals that have high organic and low carbonate contents, and then uses a two-step sieving procedure to remove contaminants from the bulk sediments. During the past five years, we have prepared a total of 64 samples for radiocarbon dating using this pre-treatment method, and 59 of them were deemed valid, a success rate of 92.2%. Thus, we believe this procedure can successfully remove contamination and optimize the sample pre-treatment for radiocarbon dating of organic-rich deposits from coastal and other environments. • Use loss-on-ignition analysis to locate the ideal sampling intervals. • Sieve each sample with 200 µm and then 100 µm sieve to remove roots and organic debris. • Acid-leach each of the sieved sediment samples (100-200 µm) with HCL to remove carbonates.

Abstract This study presents new sedimentology data and attempts to understand coastal processes, sedimentary dynamics and stratigraphic patterns of the Rio Bonito Formation (early Permian) in Paraná Basin, southern Brazil. The study was performed based on the description of five cores, located in a small-scale area - São Gabriel City - in Rio Grande do Sul State, southern Brazil. Eighteen facies were described and grouped into nine facies associations. Later, these facies associations were then grouped into three depositional systems: fluvial, tide-dominated estuary and wave-dominated shallow-marine depositional systems. A paleoenvironmental evolution is proposed using three block diagrams showing the paleoenvironmental stage (S1, S2, and S3). S1 contains the oldest part of the sedimentary record with predominance of fluvial system deposits, S2 comprises dominantly estuarine system deposits, and S3 is mostly composed of shallow-marine deposits. Stratigraphic framework showed a general retrogradacional tendency, with thickness variations along the systems tracts that allowed for the construction of a curve of accommodation changes to the Rio Bonito Formation in the region of São Gabriel during the early Permian. This study contributes to a better understanding of the fluvial discharges, tidal and oscillatory (wave) currents and their interactions and dominances along stratigraphic records of coastal deposits.

This study presents new sedimentology data and attempts to understand coastal processes, sedimentary dynamics and stratigraphic patterns of the Rio Bonito Formation (early Permian) in Paraná Basin, southern Brazil. The study was performed based on the description of five cores, located in a small-scale area -- São Gabriel City -- in Rio Grande do Sul State, southern Brazil. Eighteen facies were described and grouped into nine facies associations. Later, these facies associations were then grouped into three depositional systems: fluvial, tide-dominated estuary and wave-dominated shallow-marine depositional systems. A paleoenvironmental evolution is proposed using three block diagrams showing the paleoenvironmental stage (S1, S2, and S3). S1 contains the oldest part of the sedimentary record with predominance of fluvial system deposits, S2 comprises dominantly estuarine system deposits, and S3 is mostly composed of shallow-marine deposits. Stratigraphic framework showed a general retrogradacional tendency, with thickness variations along the systems tracts that allowed for the construction of a curve of accommodation changes to the Rio Bonito Formation in the region of São Gabriel during the early Permian. This study contributes to a better understanding of the fluvial discharges, tidal and oscillatory (wave) currents and their interactions and dominances along stratigraphic records of coastal deposits. [ABSTRACT FROM AUTHOR]

Abstract González-Acebrón et al. (2016) attributed the coastal deposits of Torre Bermeja-La Barrosa area (Cádiz, SW Spain) to the Early Pleistocene (1.3 Ma). They also considered that an extremely high-energy event, such as a tsunami, affected the basal deposits of the sequence. In this paper, both the chronological attribution and the stratigraphic-sedimentary model are discussed. Previous information shows that Sequence 1 is late Pliocene-lowermost Early Pleistocene based on biostratigraphic, magnetostratigraphic, and regional-scale stratigraphic correlation. In addition, stratigraphic, facies, and sedimentary analyses indicate that sediments attributed to Sequence 1 were formed due to south-easternward longshore currents reworking wave- and tidal-dominated coarse-grained delta sediments deposited further to the north. Highlights • Coarse-grained deposits cropping out at La Barrosa (Cádiz, SW Spain) are late Pliocene-lowermost Early Pleistocene in age. • They were formed in coastal settings related to longshore currents reworking of wave- and tide-dominated delta deposits • The age assignment and the sedimentary interpretation challenge results recently published by González-Acebrón et al. [ABSTRACT FROM AUTHOR]

Geomorphological and sedimentary records of Holocene coastal deposits may serve as archives for the local reconstruction of trends in coastal evolution and of the key forcing parameters controlling long-term change. We here present new observations on the sedimentology, chronology, and surface properties of a coupled beach ridge and coastal lagoon system located on the northern shore of San Matías Gulf, NE Patagonia, Argentina. The study is based on remotely sensed data, sediment cores, and a large number of samples dated using optically stimulated luminescence (OSL). The field site is located in a topographical depression within a cliffed shoreline composed of friable sand and gravel stones. The oldest preserved lagoonal deposits formed in the protected inner part of the system c. 2300 years ago. An up to 4-km-wide strandplain prograded rapidly between c. 1000 and 500 years in the more exposed western part of the system. Lagoonal deposition occurred primarily during the last 500 years. The chronology and spatial arrangement of landforms appear to result from a switch-over in sediment delivery probably caused by local implications of major shifts in climate regime. Even though we were not able to identify or benchmark the precise triggers of geomorphological change at Caleta de los Loros, our study presents an example of the potential importance of environmental changes on the rapid and non-linear development of coastal sedimentary systems. [ABSTRACT FROM AUTHOR]

The present work presented the first dated paleosealevel indicators and new paleogeographic reconstructions of the Island of Trindade. All evidence for Holocene sealevels point to the elevations higher than the present in the age interval between 5.06 ka and 0.55 ka. The altitude and ages of the reconstructions are in good agreement with hindcast model curves and the empirical sealevel envelope for the mainland eastern and northeastern Brazilian coast. However, the position of paleo vermetid-reef indicates that sealevel was lower than eustatic elevation, suggesting an effect of island subsidence. In contrast to the Brazilian mainland coastal zone, where conspicuous evidences of Pleistocene highstands were recorded, no evidence of sealevels predating the Holocene has ever been observed on the island. This could be attributed to intense coastal erosion and log-term island subsidence. A volcanic edifice rising more than 5500 m above the ocean floor was built by magmatic activity that extended over the late Pliocene and early Pleistocene. After the cessation of volcanic build up, the island started to shrink due to subaerial and marine erosion. During Pleistocene sealevel lowstands, alluvial fans were formed beyond the present limits of emerged areas. They were enclosed within and preserved from erosion by the Middle to Late Pleistocene lava flows and pyroclastic deposits. During Late Pleistocene sealevel highstand, intense coastal erosion removed the distal parts of the alluvial fans. It is very likely that at that time the entire coast of the island experienced intense erosion and subsidence as deduced from the absence of Pleistocene coastal deposits, which are widespread along mainland Brazilian coast. The east coast of the island was dominated by high sea cliffs sculpted into volcanic rocks. A volcanic cone was subsequently formed, when the sealevel was lower than present during the Late Pleistocene to early Holocene. During the mid to late Holocene sealevel highstand the volcanic cone was partially eroded and a bay formed, where vermetid-reefs grow and sand beach deposits prograded until the bay was infilled. During the sealevel maximum, wave-cut terraces were formed and sea cliffs were active. During the lowering of the sealevel, cliffs became inactive and vermetid-reefs were eroded. Beach erosion and aeolian deflation presently prevails, indicating a low sediment supply. [ABSTRACT FROM AUTHOR]

The Ediacaran-Cambrian Raizama Formation presents siliciclastic deposits exposed discontinuously along of the southern margin of the Amazon Craton and the Northern Paraguay Belt, Central-Western Brazil. These deposits are interpreted as progradational coastal succession conformably overling the carbonate platform succession of the Upper Araras Group. The facies and stratigraphic analysis of outcrop section were carried out in the Nobres region, State of Mato Grosso, allowed the individualization of seventeen facies, grouped into five facies associations (FA): FA1) lower shoreface, consisting of sandstone with parallel and wave-truncated lamination (microhummocky) parted by laminated mudstones, locally bioturbed by Skolithos; FA2) upper shoreface, composed by parallel and swaley cross bedded sandstone; FA3) subtidal, represented by sandstones with tangential and through cross stratifications drapped by siltstone/very fine sandstone laminae interpreted as channel and bar deposits; FA4) tidal flat is characterized by sandstones with tangential and sigmoidal cross bedding, even parallel stratification, low-angle cross bedding, mud cracks, siltstone/very fine sandstone rhythmites with flaser bedding, organized in shallowing-meter scale cycles; and FA5) distal braid plain consisting of sandstones with through cross-bedding and laterally discontinuous lags, parallel stratification and low-angle cross stratification partially reworked by wave. The sedimentation of the Raizama Formation suggests an increase in the siliciclastic supply linked to uplift regions of the Craton in the northwest of the studied area, succeeding the Araras carbonate platform deposits. Tubular trace fossils in the FA1 indicate, by the first time, the presence of burrowed organisms, what strongly points to an age near of the Ediacaran-Cambrian boundary.

Quaternary stratigraphy and sea level changes have been extensively investigated in many areas of the Mediterranean. However, numerical dating of coastal deposits and the associated paleoenvironmental information are limited for the coasts of Cyprus, principally based on radiometric and radiation-exposure geochronological techniques on fossils which bear a range of limitations and uncertainties. As such, optically stimulated luminescence (OSL) dating techniques are deemed to be the most suitable in direct dating of the coastal sediments of Cyprus. In the southeastern Cyprus, coastal dunes (aeolianites) now forming elongated ridges appear as morphological features running parallel to the current shoreline presenting an indicator of sea level and climate changes of great paleoenvironmental significance. We present our first chronological results for the exposed aeolianites and underlying littoral deposits formed along the southeastern coastal Cyprus ranging from 78.4 ± 9.9 to 56.2 ± 7.4 ka. The post-infrared-infrared stimulated luminescence (pIR-IRSL) revealed that dune formation took place during the marine isotope stages (MISs) 3, 4, and possibly 5a. Late Holocene reworking is proposed for a distinctively isolated dune with an age of ~1.3 ka ago. This study also showed that pIR-IRSL dating of feldspars may be a reliable alternative to quartz OSL dating when the quartz luminescence characteristics are unsuitable. [ABSTRACT FROM AUTHOR]

The Rio Bonito Formation (Paraná Basin) contains the thickest coal beds in Brazil, that are related to peat-swamp developed in coastal depositional systems during the early Permian. This study aims to understand the source of the coal organic matter and to distinguish depositional sub-environments along the coal-bearing interval from the southern border of the basin. The analysis was performed on sedimentological and stratigraphic data from 10 wells combined with organic petrology and geochemistry of the three coal beds. Samples were collected in different key beds from the SG-14 well, in different and strategic depths at the base (218.0 m), at the intermediate (209.0 m), and at the top (181.0 m) of the coal-bearing interval. The vitrinite reflectance measurements of the selected samples, T max values, C 29 ααα 20 S/(20 S + 20 R) ratio, and the absence of peak Ts (and presence of peak Tm) revealed the organic matter in the coal-bearing interval is thermally immature, suggesting low burial depth for the Rio Bonito Formation in the study region. Maceral composition showed predominance of vitrinite and inertinite in the three coal samples. Rock-Eval pyrolysis data indicate that the coal beds are composed of type III kerogen in the three samples, while the biomarkers indicate type II-III kerogen mixtures. The n-alkane distribution profiles suggest dominance of terrestrial organic matter in the samples, with a possible marine contribution at the top of the coal-bearing interval. The pristane/phytane (Pr/Ph) and C 27 /C 29 ααα20 R ratios (regular steranes) revealed sub-anoxic condition and land plants as major organic matter source for basal and intermediate parts of the coal-bearing interval. They also indicate an increased anoxic conditions and possible marine algal contribution toward the uppermost coal level. The presence of cone-in-cone-shaped structures (SG-07 well, depth 157.5 m) and Orbiculoidea fossils (SG-14 well, depth 192.5 m) are indicative of brackish water and support river-marine source mixtures at the top of the coal-bearing interval. The evolutive sedimentation model comprises four paleoenvironments for the Rio Bonito Formation along geological time, in which the basal part of the coal interval is interpreted as overbank deposits in a fluvial depositional system. On the other hand, the intermediate part of the coal-bearing interval was formed in bay-head delta, and the upper part was deposited in the central estuary, both in a tide- and wave-influenced estuarine context. • The coal beds originated in peat-swamps related to fluvial overbank, bay-head delta, and central estuary. • Orbiculoidea fossils and cone-cone-shaped bed have evidenced brackish water in the estuary. • Increasing anoxic conditions toward the upper coal-bearing interval corroborates the transgressive context in early Permian. • Low burial in the Rio Bonito succession can be revealed by thermal immaturity of the coal beds. [ABSTRACT FROM AUTHOR]

Lakes act as major archives for continental paleoenvironments, particularly when the evolution of lake levels over time serves as a guide for understanding regional paleohydrology and paleoclimate. In this paper, two sections from the Nachukui Formation (Turkana Depression, East African Rift System) provide a complete record of lake level variability and then paleohydrology for Lake Turkana between 1.95 and 1.72 Ma. This period corresponds to a key time during which important human evolutionary and technological innovations have occurred in East Africa and in the Turkana area. Based on sedimentary facies and sequence analyses on coastal deposits, one long-term regressive-transgressive cycle is identified between 1.95 and 1.72 Ma. Superimposed on this trend, five higher-frequency cycles of lake level change are identified between 1.87 and 1.76 Ma. Origins of these periodicities are attributed to orbital forcings. The extents of bathymetry change and shoreline migration during these periods are explored, suggesting that the period between 1.87 and 1.76 Ma was relatively dry and that climate experienced a relatively low variability. This finding differs strongly from most of the previous paleoenvironmental investigations in the region that argue high climate variability during a relatively wet period. This work emphasizes the importance of using sequence stratigraphy for analyzing lacustrine deposits. [ABSTRACT FROM AUTHOR]

The paper describes the geotechnical model of a coastal flat area facing the Adriatic Sea, between the municipalities of Cesenatico and Bellaria-Igea Marina (Emilia-Romagna region, Italy). On the basis of a large experimental database provided by the Geological, Seismic and Soil Survey of the Emilia-Romagna Authority, a stratigraphic scheme of the upper 40 m of this coastal plain subsoil has been defined and reliable estimates of parameters for the different soil units have been derived. The accurate mechanical characterization of soils, also reflecting their sedimentological framework, allows the development of a regional-scale geotechnical model providing a reliable and useful support to geotechnical engineers working in this area or similar geological environments. [ABSTRACT FROM AUTHOR]

The determination of hydraulic conductivity is a relevant topic for the characterization of widely-extended sandy coastal deposits. In the present work, the hydraulic conductivity of the Rimini Northern coastal deposits is evaluated through different procedures. Hydraulic conductivity is estimated from in situ and laboratory tests on small soil volumes, and from empirical correlations based on particle size distribution and in-situ tests. Relying on the variability ranges of the estimated parameters, a preliminary numerical water flow model of the testing area has been developed. Results can be considered as predictive of the hydraulic behavior of large soil volumes in the investigated area. [ABSTRACT FROM AUTHOR]

The presented study shows that the delivery of marine macrodebris to a high-energy coastal environment has been abundant enough over the last three decades as to allow a spatial reconstruction of morphological change based on production-date prints. A dataset of > 110 spatially discrete samples has been collected in an area affected by overwashing on the Skallingen peninsula, SW Denmark. A conceptual model for the chronological interpretation of the date prints is proposed and cross-compared with a dense time-series of satellite images and orthophotos. It appears that the litter-derived ages are capable of reproducing information on both the timing and the extent of overwash occurrence. Despite the usefulness of the method as a tool for rapidly assessing the approximate age of recent coastal deposits, the study shows the alarming degree and long-standing of marine-litter pollution on the eastern board of the southern North Sea. [ABSTRACT FROM AUTHOR]

Differentiating between forced regressive deposits from deglacial periods in high latitude domains and forced regressive deposits from the onset of glacial periods in low latitude domains is fundamental for the accurate interpretation of glacial cycles within the geological record and then for the reconstruction of palaeogeography and palaeo-climate. A forced regressive deglacial sequence is documented from the Lake Saint-Jean basin (Québec, Canada). In this area, the Late Pleistocene to Holocene sediments have recorded the Laurentide ice sheet retreat accompanied by the invasion of marine waters (Laflamme Gulf) from ca 12·9 cal kyr bp. Subsequently, fluvio-deltaic and coastal prograding wedges were deposited; they followed the base-level fall due to glacio-isostatic rebound. This succession, representing a transition from glacial to post-glacial periods within a previously glaciated area, was investigated through recent mapping, preserved landforms, facies analysis, and new optical stimulated luminescence and radiocarbon dates. Three basin-scale geological sections share a common lower part made of isolated ice-contact fan deposits overlying bedrock. Throughout the entire basin, ice-contact fans are capped by glacimarine muds. Above, fluvial and coastal prograding systems were deposited and evolved through four steps: (i) deltaic systems progressively increased in width; (ii) coastal influence on sedimentation increased; (iii) hydrographic drainage systems became more organised; and (iv) deltas graded from steep (Gilbert delta) to low-angle foresets (mouth-bar delta). Deposited during the base-level fall from glacio-isostatic rebound, the complete succession has been designated as a single falling stage system tract referred to as a deglacial falling stage system tract. It is representative of a deglaciation sequence in areas previously covered by ice during glacial periods (i.e. medium to high latitude domains). Diagnostic criteria are provided to identify such a deglacial falling stage system tract in the geological record, which may aid identification of previously unknown glacial cycles. [ABSTRACT FROM AUTHOR]

Coastal marine Holocene deposits of the Apulia region, considered as indicators of palaeoclimatic conditions, were studied. Our data show that (1) up to c. 5500 cal. yr BP, a phase of accumulation of flint pebbles from the Gargano headland occurred at the Riviera sud di Manfredonia (Adriatic coast); their transport from the Gargano headland (north of the study site) is incompatible with the current northward littoral drift and is best explained by a prevalence and dominance of NE and E winds and (2) after c. 4500 cal. yr BP, there was a rapid accumulation of sediments at the Marina di Ugento (Ionian coast), which is best explained by a prevalence and dominance of S, SW and SE winds. The two different wind regimes identified can be explained by a change in the mean pressure configuration in the central Mediterranean. The first phase (until c. 5500 cal. yr BP) consisted of more frequent cyclogenesis to the east-southeast of the Italian Peninsula, followed by a second phase (from c. 4500 cal. yr BP) of more frequent cyclogenesis to the west-northwest. The period between 5500 and 4500 cal. yr BP represents a transitional phase between the two different regimes. In other words, there was a ‘retreat’ of the central Mediterranean cyclogenesis towards the west-northwest. This pattern is contemporaneous with the termination of the African Humid period. We interpret both the ‘retreat’ of the Mediterranean cyclogenesis and the termination of the African Humid period as the expression of an expansion of the tropical dry Saharan belt. [ABSTRACT FROM AUTHOR]

Sample preparation protocols for concentrating organic material from sediments for radiocarbon dating often include a large number of steps and the use of hazardous chemicals. Thus, these protocols are often problematic for pollen-poor sediments as material can get lost or may become degraded. Pyrite in samples for radiocarbon dating hinders an effective graphitisation process and thus needs to be removed during sample preparation. Standard protocols require the use of nitric acid, a strong oxidant that corrodes organic material. Therefore, the use of nitric acid needs to be avoided when preparing pollen-poor but pyrite-rich sediments. We present a method that minimises the sample preparation steps by replacing acid treatment with heavy liquid separation. Using non-toxic LST at a density of 2.0 g cm −3 is shown to be effective for separating the organic fraction from sulphides, silicates and carbonates. We applied this method to pyrite-rich and pollen-poor sediments from Western Australia that had previously been problematic to date. The successful AMS radiocarbon dating of all samples pre-treated with LST demonstrates the effectiveness of this method. [ABSTRACT FROM AUTHOR]

Abstract: This work presents the first detailed facies analysis of the upper Nyalau Formation exposed around Bintulu, Sarawak, Malaysia. The Lower Miocene Nyalau Formation exposures in NW Sarawak represent one of the closest sedimentological outcrop analogues to the age equivalent, hydrocarbon-bearing, offshore deposits of the Balingian Province. Nine types of facies associations are recognised in the Nyalau Formation, which form elements of larger-scale facies successions. Wave-dominated shoreface facies successions display coarsening upward trends from Offshore, into Lower Shoreface and Upper Shoreface Facies Associations. Fluvio-tidal channel facies successions consist of multi-storey stacks of Fluvial-Dominated, Tide-Influenced and Tide-Dominated Channel Facies Associations interbedded with minor Bay and Mangrove Facies Associations. Estuarine bay facies successions are composed of Tidal Bar and Bay Facies Associations with minor Mangrove Facies Associations. Tide-dominated delta facies successions coarsen upward from an Offshore into the Tidal Bar Facies Association. The Nyalau Formation is interpreted as a mixed wave- and tide-influenced coastal depositional system, with an offshore wave-dominated barrier shoreface being incised by laterally migrating tidal channels and offshore migrating tidal bars. Stratigraphic successions in the Nyalau Formation form repetitive high frequency, regressive–transgressive cycles bounded by flooding surfaces, consisting of a basal coarsening upward, wave-dominated shoreface facies succession (representing a prograding barrier shoreface and/or beach-strandplain) which is sharply overlain by fluvio-tidal channel, estuarine bay or tide-dominated delta facies successions (representing more inshore, tide-influenced coastal depositional environments). An erosion surface separates the underlying wave-dominated facies succession from overlying tidal facies successions in each regressive–transgressive cycle. These erosion surfaces are interpreted as unconformities formed when base level fall resulted in deep incision of barrier shorefaces. Inshore, fluvio-tidal successions above the unconformity display upward increase in marine influence and are interpreted as transgressive incised valley fills. [Copyright &y& Elsevier]

Abstract: Geomorphologic and chronostratigraphic investigations in various coastal localities along the middle and south Patagonian Atlantic coast, from Bahía Vera (44°S) in the north to San Julián (49°S) in the south, confirm a rich sequence of Holocene beach ridge systems and littoral and valley-mouth terraces. Beach ridges are present up to 10m above current highest tide level (hTw) and date to the early mid-Holocene transgression maximum. Beach-ridge deposits represent high-energy, wave dominated coastal environments, whereas valley-mouth terraces and littoral terraces (elevations of 5.5–6.5m above hTw) developed in wave-protected coastal environments. The surface elevation of these littoral forms suggest that the middle and south Patagonian Atlantic coast is likely undergoing a slow glacio-isostatic uplift on the order of 0.3–0.4mm/a since the mid-Holocene. The early Holocene sea-level rise reached the modern coastline by 8100 14C years ago (c. 8600cal BP) at the latest. Sea level at that time was most likely near its present position. The Holocene transgression maximum lasted from 6900 to at least 6200 14C BP (c. 7400 to 6600cal BP), raising relative sea level to about 2m to a maximum of 3m above the present level, after which sea level declined to the present level. Two significant sea-level falls of at most 1m occurred: a) between 6200 and 6000 14C BP (c. 6600 to 6400cal BP), and b) between 2600 and 2400 14C BP (c. 2300 to 2050cal BP). We assume, that both significant sea-level falls were predominantly driven by eustatic changes of ocean volume, whereas both thermo-steric changes and changes of tides may also have contributed to these relatively strong sea-level drops. Gravitational changes driven by Greenland ice growth (sensu Mitrovica et al., 2001) may also have amplified any eustatic portion of sea-level fall. The trend of a general sea-level decline since the mid-Holocene transgression maximum seems to be predominantly glacio-isostatically driven. [Copyright &y& Elsevier]

Abstract: This review analyses the ostracod record in Holocene tsunami deposits, using an overview of the 2004 Indian Ocean tsunami impact on its recent populations and the associated tsunamigenic deposits, together with results from numerous investigations of other Holocene sequences. Different features such as the variability of the local assemblages, population density, species diversity, age population structure (e.g., percentages of adults and juvenile stages) or taphonomical signatures suggest that these microorganisms may be included amongst the most promising tracers of these high-energy events in marshes, lakes, lagoons or shallow marine areas. [Copyright &y& Elsevier]

Abstract: The Late Pliocene to Middle Pleistocene coastal sediments of northeastern Rhodes (Greece) were deposited in an active tectonic setting. They provide an excellent opportunity to investigate the relative roles played by climate and tectonics in sedimentary processes. The tectono-sedimentary organization of these deposits is revised in the light of an integrated study combining data from field investigations, sedimentology, bio- and magnetostratigraphy, radiometric dating, palaeoecology, and palynology. Three lithostratigraphic units are recognised: the Rhodes Formation, the newly defined Ladiko–Tsampika Formation, and the Lindos Acropolis Formation. A major erosional surface separates the Rhodes Formation from the Ladiko–Tsampika Formation, which was deposited in deep and narrow palaeovalleys. The Rhodes Formation (Late Pliocene to 1.4–1.3 Ma) comprises three Members: the Kritika, the Lindos Bay clay and the Cape Arkhangelos calcarenite. The shallow-water clastic sediments of the Ladiko–Tsampika Formation (1.3 to 0.3 Ma) are subdivided into two Members: the Ladiko (mostly sandy) and the Tsampika (predominantly clayey). The Lindos Acropolis Formation is Late Pleistocene in age. Two major transgression–regression cycles occurred prior to the Lindos Acropolis cycle. The deposition of the first cycle (Rhodes Formation) is tectonically controlled, with very high rates of vertical movements (2.6–5.2 mm/year). The second cycle (Ladiko–Tsampika Formation) records sea-level changes controlled by slow vertical motions (around 0.16 mm/year) and glacio-eustatic events with 40-kyr and 100-kyr periods. Finally, the tectonic and sedimentary evolution of Rhodes is integrated into the geodynamic context of the eastern Aegean fore-arc. [Copyright &y& Elsevier]

Coastal strandplain deposits near Umiujaq, eastern Hudson Bay, Canada, were formed under falling relative sea level conditions resulting from postglacial isostatic uplift. Ground-probing radar profiles across the strandplain reveal a lower progradational unit (LPU) discordantly overlain by an upper progradational unit (UPU), which were correlated with stratigraphic sections exposed in incised valley walls. The discordance is a wave erosion surface (WES) that separates fine shoreface sands of the LPU from coarse-sand and gravel of the UPU. Major basal downlap surfaces can be traced updip into marine terraces and define downstepping wedges. The downstepping is interpreted as representing‘autocyclic’ morphological reconfiguration rather than a response to changes in the rate of sea level fall. The internal architecture is strongly dependent on the accommodation and thus on antecedent topography. A conceptual model for strandplain deposition under falling sea level incorporates a bipartite shallowing-upward sandy succession when sufficient accommodation is available. Where accommodation space is limited, a sharp-based bar-and-beach sandbody directly overlies muddy deeper water deposits and the WES resembles a regressive surface of erosion. [ABSTRACT FROM AUTHOR]

The Barataria barrier coast formed between two major distributaries of the Mississippi River delta: the Plaquemines deltaic headland to the east and the Lafourche deltaic headland to the west. Rapid relative sea-level rise (1.03 cm year-1) and other erosional processes within Barataria Bay have led to substantial increases in the area of open water (> 775 km² since 1956) and the attendant bay tidal prism. Historically, the increase in tidal discharge at inlets has produced larger channel cross-sections and prograding ebb-tidal deltas. For example, the ebb delta at Barataria Pass has built seaward > 2.2 km since the 1880s. Shoreline erosion and an increasing bay tidal prism also facilitated the formation of new inlets. Four major lithofacies characterize the Barataria coast ebb-tidal deltas and associated sedimentary environments. These include a proximal delta facies composed of massive to laminated, fine grey-brown to pale yellow sand and a distal delta facies consisting of thinly laminated, grey to pale yellow sand and silty sand with mud layers. The higher energy proximal delta deposits contain a greater percentage of sand (75-100%) compared with the distal delta sediments (60-80%). Associated sedimentary units include a nearshore facies consisting of horizontally laminated, fine to very fine grey sand with mud layers and an offshore facies that is composed of grey to dark grey, laminated sandy silt to silty clay. All facies coarsen upwards except the offshore facies, which fines upwards. An evolutionary model is presented for the stratigraphic development of the ebb-tidal deltas in a regime of increasing tidal energy resulting from coastal land loss and tidal prism growth. Ebb-tidal delta facies prograde over nearshore sediments, which interfinger with offshore facies. The seaward decrease in tidal current velocity of the ebb discharge produces a gradational contact between proximal and distal tidal delta facies. As the tidal discharge increases and the inlet grows in dimensions, the proximal and distal tidal delta facies prograde seawards. Owing to the relatively low gradient of the inner continental shelf, the ebb-tidal delta lithosome is presently no more than 5 m thick and is generally only 2-3 m in thickness. The ebb delta sediment is sourced from deepening of the inlet and the associated channels and from the longshore sediment transport system. The final stage in the model envisages erosion and segmentation of the barrier chain, leading to a decrease in tidal discharge through the former major inlets. This process ultimately results in fine-grained sedimentation seaward of the inlets and the encasement of the ebb-tidal delta lithosome in mud. The ebb-tidal deltas along the Barataria coast are distinguished from most other ebb deltas along sand-rich coasts by their muddy content and lack of large-scale stratification produced by channel cut-and-fills and bar migration. [ABSTRACT FROM AUTHOR]