Sea-level Cycles Research Articles

Spatio-Temporal Variability of Annual Sea Level Cycle in the Baltic Sea

In coastal and semi-enclosed seas, the mean local sea level can significantly influence the magnitude of flooding in inundation areas. Using the cyclostationary empirical orthogonal function (CSEOF) method, we examine the spatial patterns and temporal variations of annual sea level cycle in the Baltic Sea based on satellite altimetry data, tide gauge data, and regional model reanalysis during 1993 and 2014. All datasets demonstrate coherent spatial and temporal annual sea level variability, although the model reanalysis shows a smaller interannual variation of annual sea level amplitude than other datasets. A large annual sea level cycle is observed in the Baltic Sea, except in the Danish straits from December to February. Compared with altimetry data, tide gauge data exhibit a stronger annual sea level cycle in the Baltic Sea (e.g., along the coasts and in the Gulf of Finland and the Gulf of Bothnia), particularly in the winter. Moreover, the maps of the maximum and minimum annual sea level amplitude imply that all datasets underestimate the maximum annual sea level amplitude. Analysis of the atmospheric forcing factors (e.g., sea level pressure, North Atlantic Oscillation (NAO), winds and air temperature), which may contribute to the interannual variation of the annual sea level cycle shows that both the zonal wind and winter NAO (e.g., from December to March) are highly correlated with the annual cycle variations in the tide gauge data in 1900–2012. In the altimetry era (1993–2014), all the atmospheric forcing factors are linked to the annual sea level cycle variations, particularly in 1996, 2010 and 2012, when a significant increase and drop of annual sea level amplitude are observed from all datasets, respectively.

Fluvial sequences and basin development in the northern Galilee Basin

ABSTRACTIn the northern Galilee Basin, 10 third-order depositional sequences have been recognised in multi-suite geophysical logs of 16 wells and boreholes. Sequences can be subdivided into genetic systems tracts characterised by geometry, facies associations, types of bounding surface, parasequence set distribution and position within the sequence. Stacking trends of parasequence sets may be observed as a shift in the sand or shale base line. These sequences reflect basinal and hinterland tectonics with a subordinate climate and sea-level cycle signature. The initial development of the northern Galilee Basin in the upper Carboniferous reflects thermal subsidence that characterised the underlying Drummond Basin. This subsidence is overprinted by the commencement of foreland-basin tectonics associated with extension in the Bowen Basin. The foreland tectonics waned before a major regional uplift occurred in the northern Galilee Basin in the middle Permian. This uplift is associated with an early phase of the Hunter–Bowen Orogeny. A quiescent period where accommodation is controlled by sea-level changes is reflected in extensive development of mires. Renewed episodic contraction overprinted on thermal sag subsidence in the Lower Triassic reflects far-field tectonics associated with the Hunter–Bowen Orogeny. In the Upper Triassic, an end-phase event of the Hunter–Bowen Orogeny inverted the Galilee Basin.

Reply to the comment of Anan et al. on "Palynological, palaeoenvironmental and sequence stratigraphical analyses of a Turonian-Coniacian sequence, Beni Suef Basin, Eastern Desert, Egypt: Implication of Pediastrum rhythmic signature by Tahoun et al. (2017) Marine and Petroleum Geology 88 (871–887)"

Abstract Herein, we reply to the allegations made by Anan et al. (2018) who claimed that the rhythmic signature of Pediastrum originally recorded and interpreted for the first time by (Tahoun et al., 2017), is a simulation of the work of El Atfy et al. (2017). This is not possible because we submitted our manuscript (which comes from an earlier version previously submitted to JMPG) almost simultaneously with the online publication of El Atfy et al. (2017); therefore, we had no chance to incorporate their work. Anan et al. (2018) raised such claims, because we provided scientific criticism to El Atfy et al. (2017) and did not follow their work blindly. Moreover, our work has different aims and approaches with respect to those used by El Atfy et al. (2017). Our main idea was to study and explain how the vertical cyclic signature of Pediastrum is connected to sea level cyclicity and to use this vertical stratigraphic signature in paleoenvironmental and sequence stratigraphic interpretation. This aim was not tackled before by Brenac and Richards (2001) and El Atfy et al. (2017). Moreover, our work was based on palynological, geophysical and lithologic data, not on mineralogical data as made by El Atfy et al., 2017). In our paper (Tahoun et al. (2017) we decided to discuss the work of El Atfy et al. (2017) because they tried to relate Pediastrum to regressive sequence systems. We found their work has several scientific mistakes that would raise much scientific controversy and lead to unsubstantiated conclusions. In our opinion, El Atfy et al. (2017) did not use reliable data and failed to provide proper scientific evidence to their conclusion. Following El Atfy et al. (2017), Anan et al. (2018) related an alleged acme of Pediastrum to regressive systems tracts, without providing any quantitative evidence of the acme and/or making a sequence stratigraphic analysis of their studied sections. Not surprisingly, the failure of Anan et al. (2018) to provide any quantitative data to support their alleged acme reinforces our argument that their study was not based on genuine data. Moreover, Anan et al. (2018) tried to flatten the conclusion made by Tahoun et al. (2017) by underestimating its sounding Pediastrum rhythmic signature-based results. Anan et al. (Op. cit.) also tried to bend the clear fact that our ideas differ from that of El Atfy et al. (2017) to look as it was their own, which is not true. Therefore, we encourage the palynologists community to read critically the work of Tahoun et al. (2017) and the work defended by Anan et al. (2018) and their allegations to confidently scrutinize the aims, data quality, and approaches presented therein to come up with an independent judgment. A detailed reply to allegations and comments of Anan et al. (Op. cit.) are handled in the forthcoming sections.

Facies variability of a lower Aptian carbonate platform succession, Tirgan Formation, eastern Kopet Dagh Basin, northeast Iran

The Lower Cretaceous (Hauterivian-lower Aptian) Tirgan Formation is a carbonate platform succession in the Kopet Dagh Basin and is up to nearly 800 m thick. This study focuses on facies variability and depositional settings of the Tirgan in the eastern part of eastern Kopet Dagh where the formation constitutes the basal part of the lower Aptian deposits. The succession developed during the final stage of evolution of Cretaceous carbonate platform in the southern Eurasian margin and could demonstrate a synchronicity with comparable successions in other areas. In the study area, the Tirgan (48 m thick) overlies Berriasian–Barremian continental strata and underlies the lower Aptian deep marine deposits. Facies analysis of Tirgan determined several facies related to open marine, ooid grainstone shoal, protected lagoon, and lower intertidal facies belts of a carbonate system. Abundant ooids, calcareous green algae, mud size carbonate, lack of evaporite evidence, and the absence of basinal deposits record deposition in warm water shallow marine settings of a carbonate ramp under a relatively humid climate. The Tirgan encompasses a single third-order depositional sequence composed of transgressive and highstand systems tracts. The transgressive package consists of intertidal, lagoon, and open marine facies intercalated with storm and shale layers showing an overall retrogradational trend. However, the highstand package consists mainly of ooid grainstone facies and displays prograding clinoforms. The lowermost lower Aptian Tirgan sequence in the study area corresponds to the basal Aptian global third-order sea level cycle. Contact of Tirgan sequence with the overlying middle to late Aptian deep marine strata is abrupt, suggesting a drowning event, which was likely the result of early Aptian extraordinary global warming.

Ichnology applied to sequence stratigraphic analysis of Siluro-Devonian mud-dominated shelf deposits, Paraná Basin, Brazil

Previous studies of the Paraná Supersequence (Furnas and Ponta Grossa formations) of the Paraná Basin in southern Brazil have yielded disparate sequence stratigraphic interpretations. An integrated sedimentological, paleontological, and ichnological model was created to establish a refined sequence stratigraphic framework for this succession, focusing on the Ponta Grossa Formation. Twenty-nine ichnotaxa are recognized in the Ponta Grossa Formation, recurring assemblages of which define five trace fossil suites that represent various expressions of the Skolithos, Glossifungites and Cruziana ichnofacies. Physical sedimentologic characteristics and associated softground ichnofacies provide the basis for recognizing seven facies that reflect a passive relationship to bathymetric gradients from shallow marine (shoreface) to offshore deposition. The vertical distribution of facies provides the basis for dividing the Ponta Grossa Formation into three major (3rd-order) depositional sequences— Siluro-Devonian and Devonian I and II—each containing a record of three to seven higher-order relative sea-level cycles. Major sequence boundaries, commonly coinciding with hiatuses recognized from previously published biostratigraphic data, are locally marked by firmground Glossifungites Ichnofacies associated with submarine erosion. Maximum transgressive horizons are prominently marked by unbioturbated or weakly bioturbated black shales. By integrating observations of the Ponta Grossa Formation with those recently made on the underlying marginal- to shallow-marine Furnas Formation, the entire Paraná Supersequence can be divided into four disconformity-bound sequences: a Lower Silurian (Llandovery-Wenlock) sequence, corresponding to lower and middle units of the Furnas; a Siluro-Devonian sequence (?Pridoli-Early Emsian), and Devonian sequences I (Late Emsian-Late Eifelian) and II (Late Eifelian-Early Givetian). Stratigraphic positions of sequence boundaries generally coincide with regressive phases on established global sea-level curves for the Silurian-Devonian.

A global spatially explicit database of changes in island palaeo‐area and archipelago configuration during the late Quaternary

AbstractMotivationPast sea level fluctuations have shaped island area and archipelago configuration. The availability of global high‐resolution data on bathymetry and past sea levels allows reconstruction of island palaeo‐geography. Studies on the role of palaeo‐area often consider only the Last Glacial Maximum, which neglects the dynamics of island fusion and fission resulting from cyclic sea level fluctuations throughout the Quaternary. Currently, no global database is available to test the role of changing island geographies driven by Quaternary sea level change on evolutionary, ecological and archaeological patterns. However, data on island palaeo‐environments is crucial for understanding insular biodiversity distributions and human settlement patterns. Here, we present the Palaeo‐Islands and Archipelago Configuration (PIAC) database, containing sea level‐driven palaeo‐geography changes over the late Quaternary of 178 islands in 27 archipelagos, and discuss its relevance, limitations and uncertainties. The R functions developed to create the PIAC database are provided to allow calculations for other islands, time steps, sea‐level curves and higher spatio‐temporal resolutions.Main types of variables containedPolygon shapefiles with archipelago configuration and tables with palaeo‐area per island.Spatial location and grainThe database has a global representation, with 27 archipelagos being covered: Aldabra, Azores, Balearic Islands, California Channel Islands, Canary Islands, Cape Verde, Comoros, Cook Islands, Crozet Islands, Dutch Caribbean, Galápagos, Gulf of Guinea, Hawaii, Inner Seychelles, Juan Fernández, Kuril Islands, Madeira, Marianas, Marquesas, Mascarenes, Phoenix Islands, Pitcairn Islands, Prince Edward Islands, Revillagigedo, Samoan Islands, Society Islands and Tristan da Cunha. All data are at 1 km2 spatial resolution.Time period and grainThe focus of this paper is on the last 35 kyr; data for the last 140 kyr are also provided. The grain is 1 kyr temporal resolution.Level of measurementData are per island, grouped per archipelago.Software formatThe data were produced in the R programming language.

Interannual sea level variability in the Pearl River Estuary and its response to El Niño–Southern Oscillation

Abstract The South China coast, especially the Pearl River Estuary (PRE) region, is prosperous and densely populated, but vulnerable to sea level changes. Sea level anomalies (SLA) during 1954–2012 from tide gauge station data and regional SLAs during 1993–2012 from satellite altimetry are analyzed and compare to the El Nino–Southern Oscillation (ENSO). Results show that sea level declines during El Nino events and rises during La Nina. Sea level in the PRE responds to ENSO with ~3–month lag. The ENSO can cause sea level in the PRE to fluctuate from −8.70 to 8.11 cm. Sea level cycles of 3 and 5 years are related to ENSO. The ENSO mechanism affecting sea level in the PRE was analyzed by identifying dominant regional and local forces. Weak/strong SLAs in most El Nino/La Nina events may be attributed to less/more seawater transport driven by anomalously weak/strong north winds and local anomalously high/low sea level pressure. Wind-driven coastal current is the predominant factor. It generated coastal seawater volume transport along a ~160 km wide cross section to decrease by 21.07% in a typical El Nino period (January 2010) and increase by 44.03% in a typical La Nina period (January 2011) as compared to an ENSO neutral situation (January 2013). Results of sea level rise and its potential mechanism provide insight for disaster protection during extreme El Nino/La Nina events.

Detailed facies analysis of the Upper Cretaceous Tununk Shale Member, Henry Mountains Region, Utah: Implications for mudstone depositional models in epicontinental seas

Lower-Middle Turonian strata of the Tununk Shale Member of the greater Mancos Shale were deposited along the western margin of the Cretaceous Western Interior Seaway during the Greenhorn second-order sea level cycle. In order to examine depositional controls on facies development in this mudstone-rich succession, this study delineates temporal and spatial relationships in a process-sedimentologic-based approach. The 3-dimensional expression of mudstone facies associations and their stratal architecture is assessed through a fully integrative physical and biologic characterization as exposed in outcrops in south-central Utah. Sedimentologic characteristics from the millimeter- to kilometer-scale are documented in order to fully address the complex nature of sediment transport mechanisms observed in this shelf muddy environment.The resulting facies model developed from this characterization consists of a stack of four lithofacies packages including: 1) carbonate-bearing, silty and sandy mudstone (CSSM), 2) silt-bearing, calcareous mudstone (SCM), 3) carbonate-bearing, silty mudstone to muddy siltstone (CMS), and 4) non-calcareous, silty and sandy mudstone (SSM). Spatial and temporal variations in lithofacies type and sedimentary facies characteristics indicate that the depositional environments of the Tununk Shale shifted in response to the 2nd-order Greenhorn transgressive-regressive sea-level cycle. During this eustatic event, the Tununk shows a characteristic vertical shift from distal middle shelf to outer shelf (CSSM to SCM facies), then from outer shelf to inner shelf environment (SCM to CMS, and to SSM facies). Shifting depositional environments, as well as changes in dominant paleocurrent direction throughout this succession, indicate multiple source areas and transport mechanisms (i.e. longshore currents, offshore-directed underflows, storm reworking). This study provides a rare documentation of the Greenhorn cycle as exposed across the entire shelf setting. High-resolution mapping of genetically-related packages facilitate the development of process-based depositional models that can be utilized for lateral correlations into the equivalent foredeep strata of the Cretaceous Interior.

Late Quaternary Fluvial History of Santa Cruz Island, California, USA

The geologic history of fluvial systems on Santa Cruz Island (SCI) is complex, involving responses to both allogenic and autogenic forcings. During periods of low or lowering sea level, canyons on the island were eroded and sediment was transported off the island onto the exposed marine shelf. When sea level rose, streams aggraded, building a sedimentary wedge that progressed from the shelf upstream into the canyons. This cycle of erosion and aggradation in response to glacial–interglacial sea-level cycles was likely repeated numerous times during the Quaternary, although clear evidence of only the most recent cycle is present in the island’s alluvial sequences. Christy, Sauces, and Pozo Canyons contain thick packages of fine-grained sediments that were deposited as a result of the interaction between autogenic depositional processes and allogenic forcing of continuous base-level rise. Other canyons on the island either have little alluvial fill due to their steep gradients or are filled with coarse-grained, recent (likely late Holocene) alluvium that covers the older alluvial deposits. Differences in the nature and extent of the alluvial exposures on SCI relative to those on neighboring Santa Rosa Island reflect differences in the local topography, geology, and ranching histories of the 2 islands.

Relative sea-level cycles and organic matter accumulation in shales of the Middle and Upper Devonian Horn River Group, northeastern British Columbia, Canada: Insights into sediment flux, redox conditions, and bioproductivity

Relative sea-level cycles and organic matter accumulation in shales of the Middle and Upper Devonian Horn River Group, northeastern British Columbia, Canada: Insights into sediment flux, redox conditions, and bioproductivity

The sedimentary succession of the last ~ 3.50 Myr in the western South Yellow Sea: Paleoenvironmental and tectonic implications

The South Yellow Sea (SYS) Basin, which is part of the West Pacific Continental Margin, began to form in the late Mesozoic to early Cenozoic as a result of regional tectonic activity in Asia. The pre-Middle Pleistocene sedimentary history of the area remains poorly understood or controversial, mainly due to a lack of long borehole cores penetrating pre-Quaternary strata. Borehole core CSDP-1 (300.10m long), the longest sediment core recovered thus far from the SYS, was drilled in 2013 in the western SYS. Recently, a reliable timescale for the core for the last ~3.50Myr was obtained by magnetostratigraphy (Liu et al., 2016a). Here we report the results of integrated analyses of the core, including sedimentary characteristics, downcore changes in environmental proxies (benthic foraminifera and ostracods), and accelerator mass spectrometry 14C and optically stimulated luminescence dates. In addition, we analyze 546km of single-channel seismic profiles and ~50km of a boomer seismic profile around the core site, and correlate the regional stratigraphy. The core sedimentary succession contains 17 depositional units (lithofacies associations) corresponding to three major seismic units, reflecting a variety of depositional environments during the last ~3.50Myr. Our results show that fluvial environments prevailed in the western SYS from ~3.50 to 1.66Ma, followed by alternations of tidal-flat to shallow-subtidal environments with fluvial environments from ~1.66 to 0.83Ma, and alternations of modern-like marine environments and fluvial environments from ~0.83Ma to the present-day in response to glacio-eustatic sea-level cycles. The depositional succession during the last ~3.50Myr was dominantly controlled by tectonism and glacio-eustatic sea-level cycles. The presumed first marine transgression since the Neogene in the western SYS at ~1.66Ma is interpreted to suggest that sea water could partially flood the Zhe-Min Uplift (ZMU) into the SYS due to tectonic subsidence, and further subsidence of the ZMU and the SYS shelf is inferred to have resulted in establishment of normal marine environments in the SYS during the highstands of glacio-eustatic sea-level cycles since ~0.83Ma. The average subsidence rates in the western SYS were ~120–165m/Myr during the last ~1.66Myr. The sedimentary succession comprises fifth- and fourth-order sequences, which are interpreted to have been driven by the 20-kyr or 41-kyr and by the 100-kyr glacio-eustatic sea-level cycles, respectively, since the late Pliocene. The sequences deposited since the Late Pleistocene are relatively complete, recording deposits from MIS 5 to MIS 1. However, the pre-Upper Pleistocene sequences show significant stratigraphic hiatuses, presumably caused by fluvial erosion during the glacial sea-level lowstands and subsequent transgressive erosion. This type of significant discontinuity in the sedimentary record can be considered to be diagnostic of shelf sequences controlled by glacio-eustatic sea-level cycles.

Seismic morphology and infilling structure of the buried channel system beneath the inner shelf off western Long Island, New York: Accessing clues to palaeo-estuarine and coastal processes

Buried channel systems are important sedimentary repositories for documenting environmental changes in response to eustatic events. Here we investigate the morphology, infilling structure, and evolutionary history of buried channel systems offshore of Long Beach Island, New York, through dense, ultra-high resolution seismic profiles. On the basis of stratigraphic superposition, characteristic of bounding seismic surfaces, seismic geometries as well as previous studies, we identify four seismic units interpreted, top-to-bottom, as: Holocene marine sand sheet (SU1); Pleistocene-Holocene channel system (SU2); younger Pleistocene outwash lobe (SU3); and older Pleistocene outwash sediments (SU4). Two sets of channel systems are observed, one shallower (SU2) and the other deeper (inside SU4). The shallower channel system, consists of both fluvial/glaciofluvial incised valley and tidal channels/inlets, incised during or near Last Glacial Maximum and was filled during the ensuing Pleistocene-Holocene transgression, associated closely with estuarine process. The channel fill sediments, the only preserved stratigraphic record of the last sea-level cycle around this area, comprises six seismic facies, which are interpreted as: fluvial/glaciofluvial lag deposits (SF1); relict estuarine complex (SF2); retrogradational barrier system (SF3); later-formed bayhead delta (SF4); an undetermined facies which has the potential to be either barrier, central basin, bayhead delta deposits, or their complex inside the incised valley (SF5); and tidal channel/inlet/flat complex outside the valley (SF6). These facies are bounded by either ravinements (bay flooding, tidal, shoreface) or sedimentary surfaces. This interpretation and seismic geometry reveal evolution of the shallower channel system experienced (1) fluvial/glaciofluvial incision and lag preservation, (2) back-filling of estuarine complex (bayhead delta and central basin sediments), (3) landward rollover of barrier system (river mouth complex), (4) progradation of a new bayhead delta that onlaps the barrier sediments, and (5) reworking and partial erosion resulting in the transgressive ravinement (T surface). This suggests that the estuarine process was the primary factor that resulted in the infilling structure. Our results indicate the deeper channel system comprises two discontinuous channel segments. Although several seismic horizons and facies are identifiable in association with this channel system, we are unable with these data to determine if these segments are connected, nor can we confidently determine the origin and filling structure of the deeper channel system.

Zambezi continental margin: compartmentalized sediment transfer routes to the abyssal Mozambique Channel

Sediment delivery to the abyssal regions of the oceans is an integral process in the source to sink cycle of material derived from adjacent continents and islands. The Zambezi River, the largest in southern Africa, delivers vast amounts of material to the inner continental shelf of central Mozambique. The aim of this contribution is to better constrain sediment transport pathways to the abyssal plains using the latest, regional, high-resolution multibeam bathymetry data available, taking into account the effects of bottom water circulation, antecedent basin morphology and sea-level change. Results show that sediment transport and delivery to the abyssal plains is partitioned into three distinct domains; southern, central and northern. Sediment partitioning is primarily controlled by changes in continental shelf and shelf-break morphology under the influence of a clockwise rotating shelf circulation system. However, changes in sea-level have an overarching control on sediment delivery to particular domains. During highstand conditions, such as today, limited sediment delivery to the submarine Zambezi Valley and Channel is proposed, with increased sediment delivery to the deepwater basin being envisaged during regression and lowstand conditions. However, there is a pronounced along-strike variation in sediment transport during the sea-level cycle due to changes in the width, depth and orientation of the shelf. This combination of features outlines a sequence stratigraphic concept not generally considered in the strike-aligned shelf-slope-abyssal continuum.

River discharge contribution to sea-level rise in the Yangtze River Estuary, China

Sea level changes in the Yangtze River Estuary (YRE) as a result of river discharge are investigated based on the monthly averaged river discharge from 1950 to 2011 at the Datong station. Quantification of the sea level contribution is made by model computed results and the sea level rates reported by the China Sea Level Bulletin (CSLB). The coastal modeling tool, MIKE21, is used to establish a depth-averaged hydrodynamic model covering the YRE and Hangzhou Bay. The model is validated with the measured data. Multi-year monthly river discharges are statistically calculated based on the monthly river discharges at Datong station from 1950 to 2011. The four characteristic discharges (frequency of 75%, 50% and 25%, and multi-year monthly) and month-averaged river discharge from 1950 to 2011 are used to study the seasonal and long-term changes of sea level. The computed sea level at the Dajishan and Lvsi stations are used to study the multi-time scale structure of periodic variation in different time scale of river discharge series. The results reveal that (1) the sea level rises as the river discharge increases, and its amplification decreases from upstream to the offshore. (2) The sea level amplification on the south coast is greater than that on the north coast. When river discharge increases by 20,000m3/s, the sea level will increase by 0.005–0.010m in most of Hangzhou Bay. (3) The sea level at the Dajishan station, influenced by river discharge, increased 0.178mm/y from 1980 to 2011. Correspondingly, the sea level rose at a rate of 2.6–3.0mm/y during the same period. These values were provided by the CSLB. The increase in sea level (1980–2011) at the Dajishan station caused by river discharge is 6.8–8.9% of the total increase in sea level. (4) The 19–20 year dominant nodal cycle of sea level at the Dajishan and Lvsi stations is in accord with 18.6 year nodal cycle of main tidal constituents on Chinese coasts. It implies that the sea-level change period on the coast of the Yangtze River is mainly controlled by tides.

Sequence stratigraphy, basin morphology and sea-level history for the Permian Kapp Starostin Formation of Svalbard, Norway

AbstractBased on seven measured sections from Svalbard, the marine strata of the Permian Kapp Starostin Formation are arranged into seven transgressive–regressive sequences (TR1–TR7) ofc. 4–5 Ma average duration, each bound by a maximum regressive surface. Facies, including heterozoan-dominated limestones, spiculitic cherts, sandstones, siltstones and shales, record deposition within inner, middle and outer shelf areas. The lowermost sequence, TR1, comprises most of the basal Vøringen Member, which records a transgression across the Gipshuken Formation following a hiatus of unknown duration. Temperate to cold, storm-dominated facies established in inner to middle shelf areas between the latest Artinskian and Kungurian. Prolonged deepening during sequences TR2 and TR3 was succeeded by a long-term shallowing-upward trend that lasted until the latest Permian (TR4–TR7). A major depocentre existed in central and western Spitsbergen while to the north, Dickson Land remained a shallow platform, leading to a shallow homoclinal ramp in NE Spitsbergen and Nordaustlandet. The Middle Permian extinction (late Capitanian) is recorded near the base of TR6 in deeper parts of the basin only; elsewhere this sequence is not recorded. Likewise the youngest sequence, TR7, extending to the upper formational contact of latest Permian age, is found only in the basin depocentre. Comparison with age-equivalent strata in the Sverdrup Basin of Canada reveals a remarkably similar depositional history, with, for example, two (third-order) sea-level cycles recorded in the Late Permian of both regions, in keeping with the global record. Sequence stratigraphy may therefore be a powerful correlative tool for onshore and offshore Permian deposits across NW Pangaea.

Late Early Miocene palaeoenvironmental changes in the North Alpine Foreland Basin

The North Alpine Foreland Basin (NAFB) experienced rapidly changing palaeoenvironmental conditions at the end of the Early Miocene (middle-to-late Burdigalian, Paratethys stages Ottnangian and Karpatian), with transformation of fully marine settings into brackish and eventually freshwater environments. These changes were related to global sea-level fluctuations, climate oscillations, and tectonic processes associated with the uplift of the Alps. This study presents a new and comprehensive data set, derived from 13 boreholes and 491 core samples from the Molasse Basin of southwest Germany, that provides a significantly better understanding of late Early Miocene palaeoenvironments in the NAFB. Based on lithostratigraphy, biostratigraphy, and palaeoecological interpretation of rich fauna and flora assemblages, we show that the upper Burdigalian sediments comprise a regressive lower segment (Grimmelfingen Formation and equivalents), as indicated by the occurrence of the bivalve Rzehakia, and a transgressive upper component (Kirchberg Formation and equivalents) characterized by the advent of new fish and mollusc assemblages. Furthermore, we present a new lithostratigraphic concept for the Kirchberg Formation, which forms an important part of the Upper Brackish Molasse (OBM). Based on biostratigraphic constraints and recently published magnetostratigraphic data, it appears that the regressive segment of the upper Burdigalian OBM sediments correlates with the end of the global third-order sea-level cycle Bur 3, while the transgressive component reflects the Karpatian transgression at the beginning of sea-level cycle Bur 4. This implies that the Karpatian transgression actually affected the Molasse Basin of southern Germany and Upper Austria, whereas previous studies had considered this part of the NAFB as terrestrial during that time span. The new results are depicted in three palaeogeographic maps for the NAFB at 18Ma, 17.5–17.1Ma and 17Ma, respectively.

Macroinvertebrate fauna and depositional environment of the lower Upper Cenomanian Oberhäslich Formation in the Saxonian Cretaceous Basin (Germany)

In Saxony (southeast Germany), the global early Late Cretaceous transgression is reflected by the onlap of shallow-marine siliciclastics of the lower Upper Cenomanian Oberhäslich Formation (Calycoceras naviculare Zone) onto the eastern Erzgebirge, the central part of the emergent Mid-European Island. Based on detailed logging of sections south of Dresden and the study of extensive collection material, the depositional environment and macroinvertebrate assemblages of the Oberhäslich Formation have been reconstructed. This unit, with a mean thickness of 10–15m, usually shows a fining-upward trend that may become reversed towards the top, was laid down in a single 3rd-order sea-level cycle and is capped by an unconformity at the base of the overlying upper Upper Cenomanian Dölzschen Formation (sequence boundary Cenomanian 5; junction of the Calycoceras naviculare and Metoicoceras geslinianum zones). The macroinvertebrate assemblage of the Oberhäslich Formation, collected mainly from bioturbated, fine- or rarely medium-grained, quartz-rich sandstones, is fairly diverse, comprising nearly 50 taxa, predominantly bivalves (94.3%). Most conspicuous and abundant are relatively large forms such as Rhynchostreon (R.) suborbiculatum (25%) and Inoceramus pictus spp. (21%), eponymous taxa of the Rhynchostreon suborbiculatum/Inoceramus pictus assemblage. Non-bivalve benthic invertebrates are rare and represented by rather poorly preserved irregular and regular echinoids, siliceous sponges, a few gastropods, crustacean remains and a single starfish. Common Thalassinoides and Ophiomorpha burrows indicate that crustaceans were an important part of the infauna. Pervasive bioturbation resulted in a post-depositional homogenization of the sediments while all body fossils are preserved as (composite) internal moulds. The guild structure of the Rhynchostreon suborbiculatum/Inoceramus pictus assemblage shows a predominance of epifaunal and semi-infaunal suspension feeders (95.3%), suggesting eutrophic and unstable “green-water conditions” of an inner-shelf setting. Deposit-feeding biota are rare. The common occurrence of articulated bivalves and storm-induced shell beds indicate episodic rapid burial, most probably by tempestites. A current-influenced, well-oxygenated and nutrient-rich environment slightly below fair-weather base is inferred for the fine-grained sandy, fossiliferous sediments of the Oberhäslich Formation.

Sedimentary environmental change induced from late Quaternary sea-level change in the Bonaparte Gulf, northwestern Australia

Low-latitude continental shelves, mixed siliciclastic–carbonate sedimentary systems, provide an understanding of sedimentary environments driven by paleoclimatological processes. The Bonaparte Gulf, northwestern Australian continental shelf, is among the widest in the world, ranging to 500 km, with shallow carbonate terraces and platforms that were exposed during periods of lower sea level. The dominant sediments type switches between carbonate and siliciclastic over a sea-level cycle. However, the mechanism of sedimentary environmental change in the Bonaparte Gulf is not clearly understood. Here, we present a record of sedimentary environmental change from ca. 24 to 35 ka that is related to sea-level variability and exposure of carbonate terraces and platforms. Multi-proxy data from a marine sediment core show a sea-level change induced switch in sedimentary environment from siliciclastic to carbonate-dominated sedimentation during the last glaciation. Radiocarbon ages constrain the timing of this switch to ca. 26 ka, associated with a local sea-level fall of −90 m.

Long-term changes in the seasonality of Baltic sea level

The seasonal cycle accounts for about 40% of the total sea level variability in the Baltic Sea. In a climate change context, changes are expected to occur, not only in mean levels but also in the seasonal characteristics of sea level. The present study addresses the quantification of changes in the seasonal cycle of sea level from a set of century-long tide gauge records in the Baltic Sea. In order to obtain robust estimates of the changes in amplitude and phase of the seasonal cycle, we apply different methods, including continuous wavelet filtering, multi-resolution decomposition based on the maximal overlap discrete wavelet transform, auto-regressive-based decomposition, singular spectrum analysis and empirical mode decomposition. The results show that all methods generally trace a similar long-term variability of the annual cycle amplitudes, and we focus on discrete wavelet analysis as the natural counterpart of classical moving Fourier analysis. In contrast to previous studies suggesting the existence of long-term changes in the seasonal cycle, in particular an increase of the annual amplitude, we find alternating periods of high and low amplitudes without any clear indication of systematic long-term trends. The derived seasonal patterns are spatially coherent, discriminating the stations in the Baltic entrance from the remaining stations in the Baltic basin, for which zonal wind accounts for typically more than 40% of the variations in amplitude.

Paleo-environmental cyclicity in the Early Silurian Yangtze Sea (South China): Tectonic or glacio-eustatic control?

The Yangtze Sea of the South China Craton experienced strong environmental perturbations during the first ~5-6Myr of the Silurian. The Lower Silurian Lungmachi Formation in the Jiaoye-1 drillcore (Chongqing, China) records three sea-level cycles (stratigraphic sequences) characterized by rapid deepening at the base of each cycle followed by slow shallowing. Each deepening event was associated with shifts toward higher marine productivity, more intensely reducing bottomwater conditions, reduced watermass restriction, lower detrital input, and enhanced siliciclastic weathering intensity. We infer control by glacio-eustasy, in which deglacial sea-level rises and concurrent climatic warming triggered the observed environmental changes. Shallowing was associated with renewed glaciation and characterized by the opposite set of conditions. The results of this study thus provide evidence in support of continued continental glaciation during the Early Silurian, i.e., following the termination of the major end-Ordovician Hirnantian glaciation. The study core also exhibits a long-term shallowing trend through the entire Lower Silurian, the origin of which may have been tectono-epeirogenic uplift of the South China Craton during the Kwangsian Orogeny.