Search

Lateglacial and Holocene summer sea-surface temperature (SST) variability in the northern North Atlantic was reconstructed based on diatom records from two sediment cores from the North Icelandic shelf. The temperature changes are discussed in relation to palaeoceanographic circulation patterns and past climatic changes. Modern diatom data from surface sediments from around Iceland and Southeast and West Greenland, with known modern environmental variables, were used as the basis for the quantitative reconstruction of summer SST. The results show that summer SSTs varied during both the Lateglacial and the Holocene, but the amplitude of SST variations during the Lateglacial was greater than that during the Holocene. No pronounced warm or cool events were recorded on the North Icelandic shelf during the GI-1e to GI-1a events (Bølling-Allerød) and the GS-1 event (Younger Dryas). The changes in SST were possibly caused by major changes in the ocean circulation pattern around Iceland, and by minor variations in the interaction between the cold and warm currents in the region. Comparison of the reconstructed summer SSTs with other marine records from the North Atlantic suggests an antiphase relationship between the oceanic climatic responses off North Iceland and in the eastern North Atlantic during the Lateglacial and the earliest part of the Holocene (the Preboreal).

A new calcareous Arctic foraminiferal species, Glomulina oculus n. sp., belonging to the suborder Miliolina has been observed in surface samples from northern Nares Strait and Petermann Fjord, NW Greenland, and off Zachariae Isbrae, NE Greenland, as well as in early Holocene sediments from the northern Baffin Bay region and on the NE Greenland shelf. In some samples, this new porcelaneous species makes up a significant fraction of the foraminiferal assemblage, particularly in samples with a relatively large sand content, and we suggest that this species is indicative of an Arctic environment with marine-terminating glaciers. Yet, further studies are needed to ascertain its full habitat range.

The Barmur Group of the Tjornes sequence in North Iceland contains data which are interpreted as up to 20 transgression-regression cycles between 5.3 and 3.2 Ma. The Barmur Group fauna is unique among Cainozoic marine faunas in the North Atlantic region north of the British Isles containing a Pliocene mollusc fauna. The Tjornes Basin was presumably an early stepping-stone for the invertebrate species migrating from the Pacific into the North Atlantic since the Miocene-Pliocene boundary. A marked faunal change, mainly visible in the lowermost part of the Serripes Zone at about 3.8 Ma, was not only connected to environmental changes in the Tjornes region but rather due to migration of at least 34 mollusc species of North Pacific origin into the North Atlantic. These species have since been among dominants in marine arctic, subarctic, and even boreal assemblages in the northern part of the Atlantic. We interpret our data as reflecting an overall change in sea-water temperature from summer temperatures between 10 and 15 °C during the deposition of the Tapes Zone and the lower part of the Mactra Zone to colder water conditions with summer temperatures between 5 and 10 °C at the top of the Serripes Zone.

Thick Quaternary sediments of the Breiðavik Group are intercalated between lava flows and tuffs on Tjornes, North Iceland. The present chapter is a compilation of lithostratigraphic and fossil data, combined with an interpretation of the sedimentary and volcanic facies. The vertical column of strata displays a rhythmic character, and a model for sedimentation during glacial-interglacial cycles in a volcanic environment is presented. The Quaternary part of the Tjornes sequence contains evidence of 14 separate glaciations with tillite horizons. The tillites are typically associated with kame and outwash conglomerates, followed at first by glacio-lacustrine and glaciomarine mudrocks and diamictites, and then by deltaic and/or bar-lagoon assemblages, fluvial sediments, and subaerial lava flows. Depositional environments are reconstructed for several steps in the geological history of the Breiðavik Group. The oldest tillite has been dated to c. 2.6 Ma. Several of the tillite beds are succeeded by marine sediments with fossils, especially in the lower part of the sequence. During the first million years of the accumulation, the deposition took place in a transitional environment while the area was subsiding, but the latter part of the geological record reflects terrestrial deposition and increased volcanism in the region.

Foraminiferal assemblages have been studied in sediments from the Barmur Group (Tjornes beds), which is part of the most complete geological Plio-Pleistocene section in Iceland, situated on the west side of the Tjornes Peninsula in northern Iceland. The Barmur Group comprises the three biozones, the Tapes Zone, the Mactra Zone, and the Serripes Zone, which represent a major part of the Pliocene. The sediments in the Tjornes section are lithified, and the registered foraminiferal assemblages represent a paleocoenosis, consisting of a residual of the most chemically and mechanically resistant tests. The foraminiferal taxa found in the three biozones of the Barmur Group are presented with their systematic affiliations, as well as their ecological and stratigraphic indication, when possible. Despite the relatively bad preservation state of the foraminiferal tests, it has been possible to attain a rough estimate of the stratigraphy and the paleoenvironmental development through each of the biozones.

According to a new revised age model which is consistent with published paleomagnetic and radiometric data, marine sedimentation in the Tjornes Basin started close to the Miocene-Pliocene boundary. The oldest part of the north-west dipping sedimentary sequence, the Tapes Zone, is not a continuous, conformable sequence, but has been dislocated laterally within the Tjorne Fracture Zone. Its basal age was previously determined by dinoflagellate stratigraphy. Above the boundary between the Tapes and Mactra Zones the sequence is continuous, but the development of a graben to the east of the present coastline changed the focus of accumulation. An erosional surface developed to the west of this graben, resulting in a gap in the presently exposed coastal section. The uppermost part of the Mactra Zone is correlated to a level within the uppermost Gilbert reversed polarity chron with an estimated age of 3.8 Ma. Serripes Zone sediments span the interval 3.8–3.2 Ma, and the lowest tillite bed of the Tjornes sequence in the Furuvik creek is dated to the Gauss-Matuyama boundary at 2.58 Ma. Volcanic units both in the coastal sections on east Tjornes and in the Grasafjall and Burfell mountains in central Tjornes expose Matuyama-Brunhes chron boundary at 0.78 Ma.

New data on the stratigraphy of Tjornes Peninsula, North Iceland, are presented. Over 25 stratigraphic sections have been measured, lithological units defined and sampled for macro- and microfauna, forming the basis of a new lithostratigraphic classification scheme for the Miocene to Pliocene part of the Tjornes sequence. Three group units are identified: the Kaldakvisl, the Barmur, and the Hoskuldsvik Groups. Geological maps reveal new details of the geological structure including right-lateral transcurrent faults at the southern margin of the Tjornes Fracture Zone, which is split up in west-northwest east-southeast trending blocks. Early subsidence and transgression towards the end of the Miocene has led to the development of a north-south trending graben structure. During the Pliocene, the axis of subsidence shifted eastward and a new graben became active east of the initial one and a Pleistocene depression in Breiðavik developed. Vertical facies changes within the Barmur Group are cyclic and repeated transgressions and regressions are inferred. Sedimentation took place in coastal and shallow-marine environments. The lowest part of the Barmur Group sediments has been preserved on laterally dislocated basement blocks, so that lithological units cannot be correlated across the separating faults. Paleontological data provide constraints on the stratigraphy.

Foraminiferal assemblages have been studied in the Early Pleistocene sediments of the Tjornes section, North Iceland. A systematic description of the foraminiferal contents in three different formations of the Breiðavik Group, i.e., the Horgi Formation, the Þrengingar Formation (Svarthamar Member), and the Mana Formation, is presented. Only the 1.5 Ma old Svarthamar Member (upper part of the Þrengingar Formation) contained enough foraminifera for stratigraphical and environmental interpretations of the Breiðavik Group sediments. The foraminiferal assemblage compositions in the Svarthamar Member indicate a change from arctic to boreal-arctic (subarctic) or even boreal conditions in the sea around Iceland just after the Olduvai event of the Matuyama time interval. This climatic cycle is comparable to the Late Pleistocene glacial-interglacial cycles in the North Atlantic and indicates a northward shift of the Polar Front to a position off North Iceland during at least a part of the Early Pleistocene.

Environmental history of the Breiðavik Group on Tjornes, North Iceland, is reconstructed based on sedimentary facies, foraminifera, and molluscs. The lithological record is characterized by repeated diamictites reflecting advances of glacial ice over the region, and during the early Pleistocene, accumulation of volcanics and sediments deposited close to sea level. The Breiðavik Group contains a unique record of Cainozoic glacier variations in the North Atlantic reflected in lithological variations where marine and terrestrial sediments are intercalated between lava flows and pyroclastic rocks. As a detailed example of the development from a full glaciation through deglaciation and interglacial conditions, we present the 1.5 Ma old Svarthamar Member which shows a lithological cycle from glacial to proglacial and then to shallow marine sedimentation coinciding with a faunal succession reflecting a change from arctic to boreal-arctic or even boreal conditions in the sea north of Iceland. The age model for the sequence indicates that this occurred just after the Olduvai event of the Matuyama chron. The amplitude of this climatic cycle is comparable to the Late Pleistocene glacial-interglacial cycles in the North Atlantic. Most of the upper part of the Breiðavik Group accumulated in a terrestrial environment.

Iceland is surrounded by a shelf with depths down to 200–500 m along its 6000 km long coastline. The tidal range is highest in the south and west, and the intertidal zone is relatively narrow in northern and eastern Iceland. Relative warm high-salinity North Atlantic Water is brought to the South and West Iceland shelf by the Irminger Current flowing clockwise around the island. The marine Polar Front with steep temperature and salinity gradients separates the Atlantic Water and the cold lower salinity Polar and Arctic waters of the East Greenland and East Icelandic Currents. The oceanography north of Iceland is highly unstable. A coastal water mass follows the coastline and shallow parts of the Icelandic shelf, flowing clockwise around Iceland. The modern marine fauna is composed of boreal and subarctic-boreal species, but also some arctic species. Several hundreds of species new to the Icelandic fauna and at least 29 mollusc species new to science were recorded when the BIOICE sampling was completed in 2004 based on sampling down to 3000 m. Up to then, sampling had been limited to c. 400 m, and most of the data had been published in issues of The Zoology of Iceland.

We analyzed the biogenic silica (BSi) content and produced a diatom-based summer sea-surface temperature (SST) reconstruction for sediment core GC4 from the Holsteinsborg Dyb, West Greenland. Our aim was to reconstruct marine productivity and climatic fluctuations during the last millennium. Increased BSi content and diatom abundance suggest relatively high marine productively during the interval of AD 1000–1400, corresponding in time to the Medieval Warm Period (MWP). The summer SST reconstruction indicates relatively warm conditions during AD 900–1100, followed by cooling after AD 1100. An extended cooling period during AD 1400–1900 is characterized by prolonged low in reconstructed SST and high sea-ice concentration. The BSi values fluctuated during this period, suggesting varying marine productivity during the Little Ice Age (LIA). There is no significant correlation between the BSi content and SST during the last millennium, suggesting that the summer SST has little influence on marine productively in the Holsteinsborg Dyb. A good correspondence between the BSi content and the element Ti counts in core GC4 suggests that silicate-rich meltwater from the Greenland ice sheet was likely responsible for changes in marine productively in the Holsteinsborg Dyb.

The chemical composition of foraminiferal calcite is widely used for studying past environmental conditions and biogeochemistry. However, high rate of microbial-derived organic matter degradation and abundant dissolved metal sources in sediment and pore waters may impede the application of paleoenvironmental proxies due to formation of secondary carbonates on the outside and/or inside of foraminiferal tests. Secondary carbonate precipitation severely alters the foraminiferal geochemistry and can be difficult to eliminate through standard cleaning procedures for foraminiferal trace element analyses. Here we present results of the mineral composition and formation sequence of diagenetic coatings on the tests of foraminifera formed under extreme anoxic conditions in the Baltic Sea deepest basin (the Landsort Deep, IODP Exp. 347, Site M0063), as well as changing trace element concentrations of authigenic carbonates on the test on a millennial time-scale. The focus is on the diagenetic carbonates present on the tests of the low-oxygen tolerant benthic foraminiferal species Elphidium selseyensis and Elphidium clavatum. We applied geochemical and imaging methods by using scanning electron microscope imaging (SEM) and energy dispersive spectroscopy (EDS), synchrotron-based x-ray fluorescence microscopy (nano-XRF), RAMAN spectroscopy and laser ablation (LA)-ICP-MS, in order to ascertain the sedimentary diagenetic processes, and the foraminiferal authigenic mineral formation sequence. The authigenic carbonates were enriched in Mg, Mn, Fe and Ba, depending on the redox environmental conditions when the authigenic carbonates were precipitated. In particular, concentrations of redox-sensitive elements such as Mn and Fe were increased in bottom waters and sedimentary pore waters under oxygen-depleted conditions in the Landsort Deep, which resulted in Mn- and Fe-enriched carbonate formation. The diagenetic alteration on foraminiferal tests provides potential opportunity to investigate past sedimentary redox environment and primary productivity in the Baltic Sea.

Funding: UK Natural Environment Research Council (NERC) grant NE/G020310/1 (K.D., W.E.N.A. and M.S) and the Carnegie Trust for the Universities of Scotland. The genetic diversity, morphology and biogeography of Ammonia specimens was investigated across the Northeast (NE) Atlantic margins, to enhance the regional (palaeo)ecological studies based on this genus. Living specimens were collected from 22 sampling locations ranging from Shetland to Portugal to determine the distribution of Ammonia genetic types across the NE Atlantic shelf biomes. We successfully imaged (via scanning electron microscopy, SEM) and genotyped 378 Ammonia specimens, based on the small subunit (SSU) rRNA gene, linking morphology to genetic type. Phylogenetic analyses enabled identification of seven genetic types and subtypes inhabiting the NE Atlantic margins. Where possible, we linked SSU genetic types to the established large subunit (LSU) T-type nomenclature of Hayward et al. (2004). SSU genetic types with no matching T-type LSU gene sequences in GenBank were allocated new T-numbers to bring them in line with the widely adopted T-type nomenclature. The genetic types identified in the NE Atlantic margins are T1, T2, T3, T6, and T15, with both T2 and T3 being split further into the subtypes T2A and T2B, and T3S and T3V respectively. The seven genetic types and subtypes exhibit different biogeographical distributions and/or ecological preferences, but co-occurrence of two or more genetic types is common. A shore-line transect at Dartmouth (South England) demonstrates that sampling position on shore (high, middle or low shore) influences the genetic type collected, the numbers of genetic types that co-occur, and the numbers of individuals collected. We performed morphometric analysis on the SEM images of 158 genotyped Ammonia specimens. T15 and the subtypes T3S and T3V can be morphologically distinguished. We can unequivocally assign the taxonomic names A. batava and A. falsobeccarii to T3S and T15, respectively. However, the end members of T1, T2A, T2B and T6 cannot be unambiguously distinguished, and therefore these genetic types are partially cryptic. However, we confirm that T2A can be assigned to A. aberdoveyensis, but caution must be taken in warm provinces where the presence of T2B will complicate the morphological identification of T2A. We suggest that T6 should not currently be allocated to the Pliocene species A. aomoriensis due to morphological discrepancies with the taxonomic description and to the lack of genetic information. Of significance is that these partially cryptic genetic types frequently co-occur, which has considerable implications for precise species identification and accurate data interpretation. Postprint

Deoxygenation affects many continental shelf seas across the world today and results in increasing areas of hypoxia (dissolved oxygen concentration ([O2])

Coastal ecosystems are subjected to both large natural variability and increasing anthropogenic impact on environmental parameters such as changes in salinity, temperature, and pH. This study documents the distribution of living benthic foraminifera under the influence of multiple environmental stressors in the Skagerrak-Baltic Sea region. Sediment core tops were studied at five sites along a transect from the Skagerrak to the Baltic Sea, with strong environmental gradients, especially in terms of salinity, pH, calcium carbonate saturation and dissolved oxygen concentration in the bottom water and pore water. We found that living foraminiferal densities and species richness were higher at the Skagerrak station, where the general living conditions were relatively beneficial for Foraminifera, with higher salinity and Ωcalc in the water column and higher pH and oxygen concentration in the bottom and pore water. The most common species reported at each station reflect the differences in the environmental conditions between the stations. The dominant species were Cassidulina laevigata and Hyalinea balthica in the Skagerrak, Stainforthia fusiformis, Nonionella aff. stella and Nonionoides turgida in the Kattegat and N. aff. stella and Nonionellina labradorica in the Öresund. The most adverse conditions, such as low salinity, low Ωcalc, low dissolved oxygen concentrations and low pH, were noted at the Baltic Sea stations, where the calcareous tests of the dominant living taxa Ammonia spp. and Elphidium spp. were partially to completely dissolved, probably due to a combination of different stressors affecting the required energy for biomineralization. Even though Foraminifera are able to live in extremely varying environmental conditions, the present results suggest that the benthic coastal ecosystems in the studied region, which are apparently affected by an increase in the range of environmental variability, will probably be even more influenced by a future increase in anthropogenic impacts, including coastal ocean acidification and deoxygenation.

The East Asian winter monsoon (EAWM) significantly impacts living conditions in a large part of Asia, and therefore, it is important to understand its major driving mechanisms. Winter sea surface temperature (SSTW) and circulation in the southern Okinawa Trough are today both primarily controlled by the EAWM. Here we present a new SSTW reconstruction for the last millennium based on a diatom record from sediment core MD05-2908, from the continental slope of the southern Okinawa Trough off northeastern Taiwan. Our reconstruction indicates that SSTW varied between 14.1 and 19.6°C over the past 1,000 years. Changes in SSTW in the southern Okinawa Trough correspond closely to the index of warm winters based on historical documents from the East Asian monsoon domain. This implies that our SSTW record can be used to reconstruct EAWM variability during the last millennium. Comparisons with the reconstructed winter Arctic Oscillation (AO, developed from historical snow anomaly events in Eastern Asia) and Arctic sea ice cover reveal a significant positive correlation between the EAWM and AO during the time interval from 1000–1400 Common Era (C.E.), coinciding with reduced sea ice cover. However, there is no significant correlation with increased sea ice cover during the interval from 1400 to 1700 C.E. This suggests that the reduction in Arctic sea ice may periodically have played a role in strengthening the relationship between the EAWM and the AO during the last millennium and that the current and future reduction in Arctic sea ice may have significant consequences for the EAWM.

We present a reconstruction of Holocene sea-ice variability from sediment core GA306-GC3, from the Holsteinsborg Dyb off West Greenland, which provides an index of palaeoceanographic and palaeoenvironmental conditions within this climatically sensitive region during the last 6700 yr. The reconstructed sea-ice record, combined with previously published proxy data, suggests that relatively warm conditions with reduced sea-ice extent prior to 5000 cal. yr BP were associated with the Holocene Thermal Maximum. Subsequent cooling and extensive sea-ice cover between ca. 5000 and 4000 cal. yr BP was followed by even colder conditions and persistent sea-ice cover during the Neoglacial cooling phase, particularly after ca. 1500 cal. yr BP. There is a positive correlation between West Greenland sea-ice cover and solar activity over the past 5000 yr, but the correlation is much weaker prior to 5000 cal. yr BP. In addition, there is a strong link between West Greenland sea ice and changes in the abundance of arctic benthic foraminifera species, related to different water masses of the West Greenland Current during the entire interval, even prior to 5000 cal. yr BP. Our findings indicate that sea-ice variability off West Greenland was driven not only by solar activity, but also by ocean circulation (the strength of cold Polar water from the East Greenland Current and warm Atlantic water from the Irminger Current).

Arctic sea ice represents an important component of the climate system, and the present reduction of sea ice in the Arctic is of major concern. Despite its importance, little is known about past changes in sea-ice cover and the underlying forcing mechanisms. Here, we use diatom assemblages from a marine sediment core collected from the West Greenland shelf to reconstruct changes in sea-ice cover over the last millennium. The proxy-based reconstruction demonstrates a generally strong link between changes in sea-ice cover and solar variability during the last millennium. Weaker (or stronger) solar forcing may result in the increase (or decrease) in sea-ice cover west of Greenland. In addition, model simulations show that variations in solar activity not only affect local sea-ice formation, but also control the sea-ice transport from the Arctic Ocean through a sea-ice–ocean–atmosphere feedback mechanism. The role of solar forcing, however, appears to have been more ambiguous during an interval around AD 1500, after the transition from the Medieval Climate Anomaly to the Little Ice Age, likely to be driven by a range of factors.

Genetic characterisation (SSU rRNA genotyping) and Scanning ElectronMicroscope (SEM) imaging of individual tests were used in tandem to determine the modern species richness of the foraminiferal family Elphidiidae (Elphidium Haynesina and related genera) across the Northeast Atlantic shelf biomes. Specimens were collected at 25 locations fromthe High Arctic to Iberia and a total of 1013 individual specimenswere successfully SEMimaged and genotyped. Phylogenetic analyses were carried out in combination with 28 other elphidiid sequences from GenBank and seventeen distinct elphidiid genetic types were identified within the sample set seven being sequenced for the first time. Genetic types cluster into sevenmain cladeswhich largely represent their generalmorphological character. Differences between genetic types at the genetic morphological and biogeographic levels are indicative of species level distinction. Their biogeographic distributions in combination with elphidiid SSU sequences from GenBank and high resolution images from the literature show that each of them exhibits species specific rather than clade specific biogeographies. Due to taxonomic uncertainty and divergent taxonomic concepts between schools we believe that morphospecies names should not be placed onto molecular phylogenies unless both the morphology and genetic type have been linked to the formally named holotype or equivalent. Based on strictmorphological criteriawe advocate using only a three stage approach to taxonomy for practical application in micropalaeontological studies. It comprises genotyping the production of a formal morphological description of the SEM images associated with the genetic type and then the allocation of the most appropriate taxonomic name by comparison with the formal type description. Using this approach we were able to apply taxonomic names to fifteen genetic types. One of the remaining two may be potentially cryptic and one is undescribed in the literature. In general the phylogeographic distribution is in agreement with our knowledge of the ecology and biogeographical distribution of the corresponding morphospecies highlighting the generally robust taxonomic framework of the Elphidiidae in time and space.

Es werden interglaziale Foraminiferen-Faunen aus dem Holstein, dem Eem und dem Holozän für den Raum Cuxhaven beschrieben. Bei den bearbeiteten Proben handelt es sich um Material aus Kernbohrungen. Die Vergesellschaftungen werden mit vorliegenden Publikationen entsprechender Vorkommen aus Nordwestdeutschland und Dänemark verglichen. Jede der 3 untersuchten Faunen hat typische Züge. Von besonderem Interesse ist die Tatsache, daß die Anwesenheit und/oder Häufigkeit bestimmter Taxa für das Gebiet der südlichen Nordsee stratigraphische Korrelationen ermöglicht., research

Two new coccolith-agglutinated foraminiferal species, Pseudobolivina islandica n. sp. and Haplophragmoides atlanticus n. sp., are described from Recent and Upper Holocene sediments at Húnaflóaáll on the North Icelandic shelf. Specimens of the two species have been found only in the small (63–106 µm) fraction using the wet-counting method. This method allows preservation of these fragile tests, which are predominantly composed of coccoliths, mainly of the species Coccolithus pelagicus (Wallich, 1877).

A high-resolution sedimentary sequence recovered from the Tagus prodelta has been studied with the objective to reconstruct multi-decadal to centennial-scale climate variability on the western Iberian Margin and to discuss the observations in a wider oceanographic and climatic context. Between ca. 100BC and AD400 the foraminiferal fauna and high abundance of Globorotalia inflata indicate advection of subtropical waters via the Azores Current and the winter-time warm Portugal Coastal Current. Between ca. AD400 and 1350, encompassing the Medieval Climate Anomaly (MCA), enhanced upwelling is indicated by the planktonic foraminiferal fauna, in particular by the high abundance of upwelling indicator species Globigerina bulloides. Relatively light δ18O values and high sea surface temperature (SST) (reconstructed from foraminiferal assemblages) point to upwelling of subtropical Eastern North Atlantic Central Water. Between ca. AD1350 and 1750, i.e. most of the Little Ice Age, relatively heavy δ18O values and low reconstructed SST, as well as high abundances of Neogloboquadrina incompta, indicate the advection of cold subpolar waters to the area and a southward deflection of the subpolar front in the North Atlantic, as well as changes in the mode of the North Atlantic Oscillation. In addition, the assemblage composition together with the other proxy data reveals less upwelling and stronger river input than during the MCA. Stronger Azores Current influence on the Iberian Margin and strong anthropogenic effect on the climate after AD1750 is indicated by the foraminiferal fauna. The foraminiferal assemblage shows a significant change in surface water conditions at ca. AD1900, including enhanced river runoff, a rapid increase in temperature and increased influence of the Azores Current. The Tagus record displays a high degree of similarity to other North Atlantic records, indicating that the site is influenced by atmospheric-oceanic processes operating throughout the North Atlantic, as well as by local changes.

Mounting evidence from proxy records suggests that variations in solar activity have played a significant role in triggering past climate changes. However, the mechanisms for sun-climate links remain a topic of debate. Here we present a high-resolution summer sea-surface temperature (SST) record covering the past 9300 yr from a site located at the present-day boundary between polar and Atlantic surface-water masses. The record is age constrained via the identification of 15 independently dated tephra markers from terrestrial archives, circumventing marine reservoir age variability problems. Our results indicate a close link between solar activity and SSTs in the northern North Atlantic during the past 4000 yr; they suggest that the climate system in this area is more susceptible to the influence of solar variations during cool periods with less vigorous ocean circulation. Furthermore, the high-resolution SST record indicates that climate in the North Atlantic regions follows solar activity variations on multidecadal to centennial time scales.

Palaeoceanographic changes over the last 6800 years are documented in a diatom record from core MD05-2908 from the southern Okinawa Trough. Changes in diatom components are used to reflect variations in the strength of the Kuroshio Current and the influence of coastal waters, and these changes are compared with records of the East Asian summer monsoon, which exerts an important influence on regional climate and oceanography. A decreasing trend in the contribution of coastal diatoms during the last 6800 years is related to the weakening of the East Asian summer monsoon during the Holocene in response to diminishing insolation and a southward shift in the intertropical convergence zone. Relatively high abundances of the Kuroshio Current indicator species during the intervals 2600-2200 and 4800-3600 cal a BP, and lower abundances during the intervals 3200-2800 and 2200-1300 cal a BP, imply that there is no consistent weakening of the Kuroshio Current during the interval 4500-3000 cal a BP-the Pulleniatina Minimum Event, which is a widespread feature in the East China Sea and the South China Sea. A major reduction in coastal diatoms at 3200cal a BP and a slight decrease in the Kuroshio Current indicator species during the interval 3200-2800 cal a BP indicate that a palaeoceanographic shift occurred in the southern Okinawa Trough, which coincided with a Northern Hemisphere climatic cooling, denoted the Neoglaciation in Europe. In addition, changes in the freshwater species component of the record are suggested mainly to result from variations in flood frequency in north-eastern Taiwan caused by typhoons. A dramatic increase in the frequency of flood events during the last millennium may have been caused by relatively strong El Nino-Southern Oscillation activity, compared with the more stable period between 6800 and 1000 cal a BP, which experienced a low frequency of flood events.

Sea–ice conditions on the North Icelandic shelf constitute a key component for the study of the climatic gradients between the Arctic and the North Atlantic Oceans at the Polar Front between the cold East Icelandic Current delivering Polar surface water and the relatively warm Irminger Current derived from the North Atlantic Current. The variability of sea ice contributes to heat reduction (albedo) and gas exchange between the ocean and the atmosphere, and further affects the deep-water formation. However, lack of long-term and high-resolution sea–ice records in the region hinders the understanding of palaeoceanographic change mechanisms during the last glacial–interglacial cycle. Here, we present a sea–ice record back to 15 ka (cal. ka BP) based on the sea–ice biomarker IP25, phytoplankton biomarker brassicasterol and terrestrial biomarker long-chain n-alkanols in piston core MD99-2272 from the North Icelandic shelf. During the Bølling/Allerød (14.7–12.9 ka), the North Icelandic shelf was characterized by extensive spring sea–ice cover linked to reduced flow of warm Atlantic Water and dominant Polar water influence, as well as strong meltwater input in the area. This pattern showed an anti-phase relationship with the ice-free/less ice conditions in marginal areas of the eastern Nordic Seas, where the Atlantic Water inflow was strong, and contributed to an enhanced deep-water formation. Prolonged sea–ice cover with occasional occurrence of seasonal sea ice prevailed during the Younger Dryas (12.9–11.7 ka) interrupted by a brief interval of enhanced Irminger Current and deposition of the Vedde Ash, as opposed to abruptly increased sea–ice conditions in the eastern Nordic Seas. The seasonal sea ice decreased gradually from the Younger Dryas to the onset of the Holocene corresponding to increasing insolation. Ice-free conditions and sea surface warming were observed for the Early Holocene, followed by expansion of sea ice during the Mid-Holocene.

A diatom-based sea-ice concentration (SIC) transfer function was developed by using 72 surface samples from west of Greenland and around Iceland, and validated against associated modem SIC. Canonical correspondence analysis on surface sediment diatoms and monthly average of SIC indicated that April SIC is the most important environmental factor controlling the distribution of diatoms in the area, justifying the development of a diatombased SIC transfer function. The agreement between reconstructed SIC based on diatoms from West Greenland and the satellite and modelled sea-ice data during the last -75 yr suggests that the diatom-based SIC reconstruction is reliable for studying the palaeoceanography off West Greenland.Relatively warm conditions with a strong influence of the Irminger Current (IC) were indicated for the early part of the record (-5000-3860 cal. yr BP), corresponding in time to the latest part of the Holocene Thermal Maximum. Between 3860 and 1510 cal. yr BP, April SIC oscillated around the mean value (55%) and during the time interval 1510-1120 cal. yr BP and after 650 cal. yr BP was above the mean, indicating more extensive sea-ice cover in Disko Bugt.Agreement between reconstructed April SIC and changes in the diatom species suggests that the sea-ice condition in Disko Bugt was strongly influenced by variations in the relative strength of two components of the West Greenland Current, i.e. the cold East Greenland Current and the relatively warm IC. Further analysis of the reconstructed SIC record suggests that solar radiation may be an important forcing mechanism behind the historic sea-ice changes. (C) 2014 Elsevier B.V. All rights reserved.

Revised diatom and new dinoflagellate cyst and benthic foraminiferal data from the eastern Baltic Sea have refined our understanding of Eemian (Last Interglacial; 131–119.5 ka) sea-level change on the Russian Karelia, a former seaway linking the Baltic to the White Sea. Results from Peski, eastern Baltic show the initiation of marine conditions just before 131 ka in the latest Saalian, after the opening of a connection to the North Sea. Following the onset of the Eemian marine highstand and the opening of the White Sea connection at around 130.25 ka, near-fully marine conditions persisted in the eastern Baltic area for ca 6 kyr, until ca 124 ka. For most of the Eemian, a strong thermal stratification in the eastern Baltic resulted from an Arctic and possible North Atlantic water component from the White Sea merging with warmer waters from the North Sea. From ca 124 ka, decreasing salinity indicates the end of the marine highstand and a simultaneous closure of the Baltic Sea–White Sea connection, i.e. a duration of ca 6 kyr for this seaway. The main influence of White Sea inflow appears to be restricted to the eastern Baltic area, although a large submerged area in the Russian Karelia associated with temperate Atlantic waters could have assisted in creating a more oceanic climate for Central Europe.

This work was funded by the Natural Environment Research Council (NERC) of the United Kingdom (grant NE/G020310/1 to K.D., W.E.N.A. and M.S.) and the Carnegie Trust for the Universities of Scotland. M.S. was supported by the Swiss National Science Foundation (SNSF, fellowships for advanced researchers PA00P2_126226 and PA00P2_142065). Genetic characterisation (SSU rRNA genotyping) and Scanning Electron Microscope (SEM) imaging of individual tests were used in tandem to determine the modern species richness of the foraminiferal family Elphidiidae (Elphidium, Haynesina and related genera) across the Northeast Atlantic shelf biomes. Specimens were collected at 25 locations from the High Arctic to Iberia, and a total of 1013 individual specimens were successfully SEM imaged and genotyped. Phylogenetic analyses were carried out in combination with 28 other elphidiid sequences from GenBank and seventeen distinct elphidiid genetic types were identified within the sample set, seven being sequenced for the first time. Genetic types cluster into seven main clades which largely represent their general morphological character. Differences between genetic types at the genetic, morphological and biogeographic levels are indicative of species level distinction. Their biogeographic distributions, in combination with elphidiid SSU sequences from GenBank and high resolution images from the literature show that each of them exhibits species-specific rather than clade-specific biogeographies. Due to taxonomic uncertainty and divergent taxonomic concepts between schools, we believe that morphospecies names should not be placed onto molecular phylogenies unless both the morphology and genetic type have been linked to the formally named holotype, or equivalent. Based on strict morphological criteria, we advocate using only a three-stage approach to taxonomy for practical application in micropalaeontological studies. It comprises genotyping, the production of a formal morphological description of the SEM images associated with the genetic type and then the allocation of the most appropriate taxonomic name by comparison with the formal type description. Using this approach, we were able to apply taxonomic names to fifteen genetic types. One of the remaining two may be potentially cryptic, and one is undescribed in the literature. In general, the phylogeographic distribution is in agreement with our knowledge of the ecology and biogeographical distribution of the corresponding morphospecies, highlighting the generally robust taxonomic framework of the Elphidiidae in time and space. Publisher PDF

[1] In this study, we use IP25 and alkenone biomarker proxies to document the subdecadal variations of sea ice and sea surface temperature in the subpolar North Atlantic induced by the decadally paced explosive tropical volcanic eruptions of the second half of the thirteenth century. The short- and long-term evolutions of both variables were investigated by cross analysis with a simulation of the IPSL-CM5A LR model. Our results show short-term ocean cooling and sea ice expansion in response to each volcanic eruption. They also highlight that the long response time of the ocean leads to cumulative surface cooling and subsurface heat buildup due to sea ice capping. As volcanic forcing relaxes, the surface ocean rapidly warms, likely amplified by subsurface heat, and remains almost ice free for several decades.

The coastal cliff section at Kas Hoved in northern Denmark represents one of the largest exposures of marine interglacial deposits in Europe. High-resolution analyses of sediments, foraminifera, ostracods, and stable isotopes (oxygen and carbon) in glacial-interglacial marine sediments from this section, as well as from two adjacent boreholes, are the basis for an interpretation of marine environmental and climatic change through the Late Elsterian-Holsteinian glacial-interglacial cycle. The overlying glacial deposits show two ice advances during the Saalian and Weichselian glaciations. The assemblages in the initial glacier-proximal part of the marine Late Elsterian succession reveal fluctuations in the inflow of sediment-loaded meltwater to the area. This is followed by faunal indication of glacier-distal, open marine conditions, coinciding with a gradual climatic change from arctic to subarctic environments. Continuous marine sedimentation during the glacial-interglacial transition is presumably a result of a large-scale isostatic subsidence caused by the preceding extended Elsterian glaciation. The similarity of the climatic signature of the interglacial Holsteinian and Holocene assemblages in this region indicates that the Atlantic Ocean circulation was similar during these two interglacials, whereas Eemian interglacial assemblages indicate a comparatively high water temperature associated with an enhanced North Atlantic Current. The foraminiferal zones are correlated with other Elsterian-Holsteinian sites in Denmark, as well as those in the type area for the Holsteinian interglacial in northern Germany and the southern North Sea. Correlation of the NW European Holsteinian succession with the marine isotope stages MIS 7, 9 or 11 is still unresolved.

Palaeoenvironmental and14C reservoir age variability in the Limfjord, a sound through northern Jutland, Denmark, was investigated for the period 7300 to 1300 cal yr BP. Shells and bulk sediment samples from a core from a former inlet, Kilen, were analysed by radiocarbon dating and stable isotope (C/N) measurements. A strong correlation between the C/N ratios and δ13C values verifies that these are good carbon source indicators and thus allow environmental reconstructions. Furthermore, δ13C values are correlated with salinity in the photic zone, inferred quantitatively from diatom assemblages. They are therefore used to differentiate between brackish and marine palaeo-conditions.14C reservoir ages of shells vary from Δ R=−140 to +30014C years. Between 7300 and 5400 cal. yr BP, reservoir age and stable isotope values are highly variable and indicate mixing of marine water and brackish surface waters with hard water effects. After 5400 cal. yr BP, the Δ R values stabilise and show an increasingly marine environment, with14C reservoir ages close to 400 years (Δ R=0). After 2000 cal. yr BP, Kilen becomes brackish. Reservoir ages and stable isotope values are again highly variable and δ13C and C/N values are no longer correlated. Before 4000 cal. yr BP, δ15N values vary by only 1‰ and do not reflect the changes in the marine environment. A δ15N increase between 3500 and 2000 cal. yr BP signifies enhanced organic productivity or a change in agricultural practices.

A high-resolution diatom record from site MD05-2908 in the Southern Okinawa Trough, East China Sea, reveals pronounced multidecadal- to centennial-scale palaeoceanographic changes throughout the last millennium. Summer sea-surface salinity (SSS) was reconstructed using a weighted averaging partial least squares diatom-based training set. The reconstructed SSS shows slightly decreasing values during the period AD 9051930 with considerable fluctuations superimposed on this general trend. Relatively high-salinity conditions during the interval AD 9051450 probably suggest a low flood frequency in north-eastern Taiwan. Furthermore, the high SSS values are associated with a strong and stable influence of the Kuroshio Current on the Southern Okinawa Trough during the Medieval Climate Anomaly. The period AD 14501930 is characterized by three low-salinity intervals (AD 14501500, AD 16251725 and AD 17701880) separated by periods of relatively high salinity. The low SSS intervals indicate increased freshwater discharge into the Southern Okinawa Trough during the Little Ice Age, probably as a result of higher flood frequencies in north-eastern Taiwan. Spectral and wavelet analyses suggest that this pattern was linked to multidecadal variations in summer SSS, presumably associated with the Pacific Decadal Oscillation. Copyright (c) 2012 John Wiley & Sons, Ltd.

Sediment cores from Kriegers Flak in the southwestern Baltic Sea provide a unique possibility to study the Middle Weichselian history of the Baltic Basin. Three Weichselian interstadial units have been identified and are attributed to Marine Isotope Stage 3 (MIS 3, 60–25 ka). The oldest unit A is characterized by a deglaciation sequence, gradually turning into brackish-water clay. The low-diversity benthic foraminiferal fauna, stable oxygen isotope values and Mg/Ca ratios indicate low temperature and salinity for unit A. A hiatus separates unit A from the overlying unit B, which was deposited in wetlands and shallow lakes between 42 and 36 cal. ka BP. Macrofossil and pollen analyses indicate deposition of unit B in an area dominated by a tree-less open tundra environment, possibly with some birch and pine in sheltered positions. The uppermost unit C is characterized by clay deposition, including redeposition of material from older sediments (unit B). Optically stimulated luminescence (OSL) ages indicate deposition of unit C between 26 and 28.5 ka. Radiocarbon ages of 39 and 40 cal. ka BP for unit C are considered to be too old. The following depositional model is suggested: (I) Isostatic depression of the region after an advance of the Scandinavian Ice Sheet (SIS), most likely the Ristinge ice advance, previously dated to c. 55–50 ka, enabled an inflow of marine waters into the Baltic Basin during the deposition of unit A. (II) Isostatic rebound caused a regression at Kriegers Flak, and a hiatus between units A and B. (III) Wetlands and smaller lakes formed in the uplifted area between 42 and 36 cal. ka BP (unit B). (IV) Deposition of glaciolacustrine clays at Kriegers Flak demonstrates that a growing SIS dammed Kattegat and the Baltic Basin c. 28.5 to 26 ka. The new evidence from Kriegers Flak provides a solid framework for future MIS 3 palaeoenvironmental reconstructions in the circum-Baltic area.

Luoto, T.P., Nevalainen, L., Kubischta, F., Kultti, S., Knudsen, K.L. and Salonen, V.‐P., 2011: Late Quaternary ecological turnover in high arctic Lake Einstaken, Nordaustlandet, Svalbard (80° N). Geografiska Annaler: Series A, Physical Geography, 93, 337–354. DOI:10.1111/j.1468‐0459.2011.00435.xAbstractMultiproxy palaeolimnological analyses of a sediment core record from Lake Einstaken, Nordaustlandet, give insight into long‐term ecological and environmental dynamics in the High Arctic Svalbard during the last c. 13-000 cal yr bp. Fossil remains of foraminifera, chironomidae, cladocera and diatoms (Bacillariophyta) revealed several distinct ecological turnovers during the late Quaternary. The foraminiferal assemblages in a marine interval in the lower part of the core indicated one distinct faunal turnover and two subsequent minor changes. The foraminiferal assemblages reflected high‐arctic, shallow‐water conditions in an area of changing salinity conditions. A development of gradually more restricted ma...

Kubischta, F., Knudsen, K.L., Ojala, A.E.K. and Salonen, V.-P., 2011. Holocene benthic foraminiferal record from a high-arctic fjord, Nordaustlandet, Svalbard. Geografiska Annaler: Series A, Physical Geography, 93, 227–242. DOI: 10.1111/j.1468-0459.2011.00434.x ABSTRACT This study presents the results of benthic foraminiferal analyses of a marine core record from about 100 m water depth in the fjord environment of Isvika bay, Nordaustlandet, Svalbard. During the Last Glacial Maximum, the bay was glaciated by the north-western sector of the Svalbard-Barents Sea Ice Sheet. The foraminiferal assemblages reflect glaciomarine conditions during deglaciation and early Holocene (about 11 250–9640 cal. yr bp) followed by glacier-distal environment in an open fjord with relatively high influence of Atlantic waters from the open ocean (9640–7430 cal. yr bp). A subsequent foraminiferal indication of a glacial advance was followed by deposition of a diamicton unit within a short time period at 5800–5700 cal. yr bp. The mid- and late Holocene were characterized by assemblages indicating restricted open-ocean connection and gradually more severe conditions, which are considered to be caused partly by a gradual cooling and freshening of the Atlantic water inflow to the shelf area and partly by a continuous isostatic uplift of the area. The foraminiferal record shows that the environmental changes in Murchisonfjorden are not just an effect of changes in solar insolation but are also influenced by local processes, as well as changes in the Atlantic water inflow to the northern Svalbard shelf and to the fjord via Hinlopenstretet.

A multiproxy study of Eemian Stage sediments in two core records, Licze and Obrzynowo, in the Gulf of Gdansk area of northern Poland, shows that the brackish-marine interglacial conditions were determined partly by regional environmental changes and partly by local changes of the river outflow from the Vistula into the southern Baltic Sea. Correlation of the sediments with the Eemian is based on pollen analysis of the Obrzynowo record, showing the presence of regional pollen zones (RPAZ) E2–E6, combined with previously published pollen analyses from Licze (RPAZ E1–E7). A floating chronology is established on the basis of correlation with the annually laminated Bispingen sequence. Diatoms, foraminifera and ostracods are used as marine environmental proxies at both sites. An indication of marine conditions as early as pollen zone E1 or E2 at Licze and close to the E2–E3 boundary at Obrzynowo reflects the rapid relative sea-level rise in the area, which proceeded through ∼3000 years. A major salinity increase c. 1100 years after the beginning of the Eemian (early pollen zone E4) at both sites may be related to the opening of the Danish Straits. The Obrzynowo site became isolated from the sea at c. 3500 years (early pollen zone E5), whereas marine conditions continued at Licze until c. 7000 years, that is, throughout pollen zone E5. Gradually shallower water after c. 5000 years presumably resulted from progradation of the rivers combined with isostatic rebound of the area before final isolation from the sea at c. 7000 years.

Diatom assemblages from Holsteinsborg Dyb on the West Greenland shelf were analysed with high temporal resolution for the last 1200 years. A high degree of consistency between changes in frequency of selected diatom species and instrumental data from the same area during the last 70 years confirms the reliability of diatoms (particularly sea-ice species and warm-water species) for the study of palaeoceanographic changes in this area. A general cooling trend with some fluctuations is marked by an increase in sea-ice species throughout the last 1200 years. A relatively warm period with increased influence of Atlantic water masses of the Irminger Current (IC) is found at ad 750–1330, although with some oceanographic variability after ad 1000. A pronounced oceanographic shift occurred at ad 1330, corresponding in time to the transition from the so-called ‘Medieval Warm Period’ (MWP) to the ‘Little Ice Age’ (LIA). The LIA cold episode is characterized by three intervals with particularly cold sea-surface conditions at ad 1330–1350, ad 1400–1575 and ad 1660–1710 as a result of variable influence of Polar waters in the area. During the last 70 years, two relatively warm periods and one cold period (the early 1960s to mid-1990s) are indicated by changes in the diatom components. Our study demonstrates that sedimentary records on the West Greenland shelf provide valuable palaeoenvironment data that confirm a linkage between local and large-scale North Atlantic oceanographic and atmospheric oscillations.

Knudsen, K. L., Jiang, H., Kristensen, P., Gibbard, P. L. & Haila, H. 2011: Early Last Interglacial palaeoenvironments in the western Baltic Sea: benthic foraminiferal stable isotopes and diatom-based sea-surface salinity. Boreas, 10.1111/j.1502-3885.2011.00206.x. ISSN 0300-9483. Stable isotopes from benthic foraminifera, combined with diatom assemblage analysis and diatom-based sea-surface salinity reconstructions, are used for the interpretation of changes in bottom- and surface-water conditions through the early Eemian at Ristinge Klint in the western Baltic Sea. Correlation of the sediments with the Eemian Stage is based on a previously published pollen analysis that indicates that they represent pollen zones E2–E5 and span ∼3400 years. An initial brackish-water phase, initiated c. 300 years after the beginning of the interglacial, is characterized by a rapid increase in sea-surface and sea-bottom salinity, followed by a major increase at c. 650 years, which is related to the opening of the Danish Straits to the western Baltic. The diatoms allow estimation of the maximum sea-surface salinity in the time interval of c. 650–1250 years. After that, slightly reduced salinity is estimated for the interval of c. 1250–2600 years (with minimum values at c. 1600–2200 years). This may be related to a period of high precipitation/humidity and thus increased freshwater run-off from land. Together with a continuous increase in the water depth, this may have contributed to the gradual development of a stratified water column after c. 1600 years. The stratification was, however, particularly pronounced between c. 2600 and 3400 years, a period with particularly high sea-surface temperature, as well as bottom-water salinity, and thus a maximum influence of Atlantic water masses. The freshwater run-off from land may have been reduced as a result of particularly high summer temperatures during the climatic optimum.

Erbs-Hansen, D. R., Knudsen, K. L., Gary, A. C., Jansen, E., Gyllencreutz, R., Scao, V. & Lambeck, K. 2011: Late Younger Dryas and early Holocene palaeoenvironments in the Skagerrak, eastern North Atlantic: a multiproxy study. Boreas, 10.1111/j.1502-3885.2011.00205.x. ISSN 0300-9843 A high-resolution study of palaeoenvironmental changes through the late Younger Dryas and early Holocene in the Skagerrak, the eastern North Atlantic, is based on multiproxy analyses of core MD99-2286 combined with palaeowater depth modelling for the area. The late Younger Dryas was characterized by a cold ice-distal benthic foraminiferal fauna. After the transition to the Preboreal (c. 11 650 cal. a BP) this fauna was replaced by a Cassidulina neoteretis-dominated fauna, indicating the influence of chilled Atlantic Water at the sea floor. Persisting relatively cold bottom-water conditions until c. 10 300 cal. a BP are presumably a result of an outflow of glacial meltwater from the Baltic area across south-central Sweden, which led to a strong stratification of the water column at MD99-2286, as also indicated by C. neoteretis. A short-term peak in the C/N ratio at c. 10 200 cal. a BP is suggested to indicate input of terrestrial material, which may represent the drainage of an ice-dammed lake in southern Norway, the Glomma event. After the last drainage route across south-central Sweden closed, c. 10 300 cal. a BP, the meltwater influence diminished, and the Skagerrak resembled a fjord with a stable inflow of waters from the North Atlantic through the Norwegian Trench and a gradual increase in boreal species. Full interglacial conditions were established at the sea floor from c. 9250 cal. a BP. Subsequent warm stable conditions were interrupted by a short-term cooling around 8300–8200 cal. a BP, representing the 8.2 ka event.

Our study of spatial and temporal marine reservoir age changes on the North Icelandic shelf is based on two high-resolution 1000-year sedimentary records from IMAGES core sites MD99-2273 and MD99-2275, located at 650 m and 470 water depths, respectively. The sedimentary and fossil record is extremely sensitive to past oceanographic and climatic changes in this region. It has been demonstrated that the position of the Polar Front across the shelf has been very dynamic through the last millennium, and our results show that deviations in the marine reservoir ages can be used as a palaeoceanographic tool for tracing changes in the water masses. The presence of historically and terrestrially dated tephra markers from Icelandic volcanoes makes it possible to construct a reliable tephrochronological age-depth model for each of the marine sediment cores. A comparison of these age models with age models based on calibrated AMS radiocarbon age determinations of marine molluscs displays major deviations through the last 1000 years. The discrepancy between the two types of age models shows that there was an average reservoir age of about 650 years at MD99-2273 and 590 years at site MD99-2275, with considerable changes through time. This is suggested to be related to a generally high, but fluctuating, inflow of apparently old Polar waters to the area. A comparison with the distribution of two benthic foraminiferal indicator species in the cores, one for Polar and Arctic water masses (Islandiella norcrossi) and one for Atlantic Water (Cassidulina neoteretis), as well as with different proxies for sea-ice cover in the area, shows that there was an increase in the penetration of cold Polar and Arctic water masses after AD 1300, i.e. during the Little Ice Age, at both sites, resulting in an increase in the reservoir ages. Relatively high reservoir ages throughout the last millennium at the deepest core site (MD99-2273) can be attributed to a continuously high Polar Water influence at the sea floor. The location of this site to the west of the Kolbeinsey Ridge, which has acted as a submarine barrier throughout the Holocene, may have contributed to a relatively high influence of cold Denmark Strait overflow water in this area.

Benthic foraminiferal assemblages from Nordaustlandet, Svalbard, are described for the first time with the objective of reconstructing the palaeoenvironmental conditions in the area during the late Quaternary. Investigations were carried out on marine deposits exposed along the southern shores of Murchisonfjorden. Five foraminiferal assemblages (A1–A5), representing different palaeoenvironmental conditions, were identified from the marine intervals, i.e., the Cassidulina reniforme–Elphidium albiumbilicatum assemblage (A1) from the Early Weichselian, the Islandiella helenae–Cibicides lobatulus assemblage (A2) from the Early Weichselian, the Cibicides lobatulus–Cassidulina reniforme assemblage (A3) from marine isotope stage 3, the Elphidium albiumbilicatum assemblage (A4) from the early Holocene and the Astrononion gallowayi assemblage (A5) from the mid-Holocene. Assemblages A1–A5 are compared with modern and fossil Quaternary assemblages from Arctic regions. Particularly notable is the fact that a well-defined Middle Weichselian assemblage in Svalbard is described for the first time, i.e., the Cibicides lobatulus– Cassidulina reniforme assemblage. All the assemblages from Nordaustlandet represent glacier-distal, inner-shelf environments with an open connection to the ocean. The results reveal the occurrence of three marine intervals (ice-free periods) in the north-western part of Nordaustlandet during the Weichselian, as well as ice-free conditions during most of the Holocene. A comparison of the assemblages from Nordaustlandet with previously published foraminiferal zones from onshore sections elsewhere in Svalbard show some degree of similarity, but also show considerable variation in species compositions, presumably caused by local environmental differences.

Lithostratigraphy and chronostratigraphy of samples from 18 deep boreholes in Vendsyssel have resulted in new insight into the Late Weichselian glaciation history of northern Denmark. Prior to the Late Weichselian Main advance c. 23-21 kyr BP, Vendsyssel was part of an ice-dammed lake where the Ribjerg Formation was deposited c. 27-23 kyr BP. The timing of the Late Weichselian deglaciation is well constrained by the Main advance and the Lateglacial marine inundation c. 18 kyr BP, and thus spans only a few millennia. Rapid deposition of more than 200 m of sediments took place mainly in a highly dynamic proglacial and ice-marginal environment during the overall ice recession. Mean retreat rates have been estimated as 45-50 m/yr in Vendsyssel with significantly higher retreat rates between periods of standstill and re-advance. The deglaciation commenced in Vendsyssel c. 20 kyr BP, and the Troldbjerg Formation was deposited c. 20-19 kyr BP in a large ice-dammed lake in front of the receding ice sheet, partly as glaciolacustrine sediments and partly as rapid and focused sedimentation in prominent ice-contact fans, which make up the Jyske As and Hammer Bakker moraines. In the northern part of central Vendsyssel, at least four generations of north-south orientated tunnel valleys are identified, each generation related to a recessional ice margin. This initial deglaciation was interrupted by a major re-advance from the east c. 19 kyr BP, which covered most of Vendsyssel. An ice-dammed lake formed in front of the ice sheet as it retreated towards the east; the Morild Formation was deposited here c. 19-18 kyr BP. Related to this stage of deglaciation, eight ice-marginal positions have been identified based on the distribution of large tunnel-valley systems and pronounced recessional moraines. The Morild Formation consists of glaciolacustrine sediments, including the sediment infill of more than 190 m deep tunnel valleys, as well as the sediments in recessional moraines, which were formed as ice-contact sedimentary ridges, possibly in combination with glaciotectonic deformation. The character of the tunnel-valley infill sediments was determined by proximity to the ice margin. During episodes of rapid retreat of the ice margin, tunnel valleys were quickly abandoned and filled with fine-grained sediments in a distal setting. During slow retreat of the ice margin, tunnel valleys were filled in an ice-proximal environment, and the infill consists of alternating layers of fine- to coarse-grained sediments. At c. 18 kyr BP, Vendsyssel was inundated by the sea, when the Norwegian Channel Ice Stream broke up, and a succession of marine sediments (Vendsyssel Formation) was deposited during a forced regression. (Less)

The Quaternary sedimentary succession in Vendsyssel, northern Denmark, contains a unique, high-resolution record of the last interglacial and glacial periods. There is still much debate, however, about the timing and ice extent in this southwestern part of the Scandinavian Ice Sheet, particularly during the Middle Weichselian. In this study, a detailed lithostratigraphical subdivision is established for the Late Saalian to Middle Weichselian Skaerumhede Group on the basis of numerous, up to 250 m deep, boreholes in Vendsyssel. The sediments mainly consist of marine clays, glaciolacustrine sediments and tills, and the total thickness of the Skaerumhede Group is up to 140 m. Marine intervals have been used as stratigraphical marker units to separate the formations indicative of ice-sheet activity in Vendsyssel, and the timing of the events has been constrained by a large number of optically stimulated luminescence (OSL) and radiocarbon ages. The Skaerumhede Group is subdivided into seven formations and two members, reflecting shifts between marine and terrestrial sedimentation caused by fluctuations of the Scandinavian Ice Sheet and changes in sea level. The lowermost Skaerumhede Till Formation was deposited directly on top of the bedrock during the Warthe advance c. 160-140 kyr BP. Above, there are fine-grained marine sediments, subdivided into the Lower, Middle and Upper Skaerumhede Clay Formations. The marine formations are separated by the Br circle divide nderslev Formation related to the Sunds circle divide re ice advance from the north c. 65-60 kyr BP, and the Asted Formation, deposited during the Ristinge advance from an east-southeastern direction c. 55-50 kyr BP. The uppermost formation in the group is the L circle divide nstrup Klint Formation, which is an upwards-coarsening sequence of mainly glaciolacustrine sediments deposited prior to the Kattegat advance c. 30-29 kyr BP. The new evidence from Vendsyssel has shown that the Skaerumhede Group covers a large area, and that it can be used as a regional stratigraphical marker horizon. Furthermore, it contributes to a better understanding of the timing and extent of glacial events during the Late Saalian to Middle Weichselian in southwest Scandinavia.

The marine Quaternary of Vendsyssel has been studied in a series of new boreholes in the area, and the climatic development is discussed on the basis of foraminiferal assemblages and stable isotopes. The foraminiferal zones are correlated with previously published records from northern Denmark, and the spatial local and regional distribution is discussed in details based on the new evidence. The new data show that the marine sedimentation in Vendsyssel was not continuous from the Late Saalian to the Middle Weichselian, as previously thought. For example, there is indication of a hiatus at our key site, Asted Vest in the central part of Vendsyssel, at the transition between regional foraminiferal zones N4 and N3, i.e. at the Late Saalian (MIS 6) - Eemian (MIS 5e) transition. The hitherto most complete Early Weichselian succession (zone N2) in Vendsyssel is presented from Asted Vest. Deposits from the Early Weichselian sea-level lowstands (MIS 5d and 5b) may, however, be missing in parts of the area. Two major breaks in the marine deposition during the Middle Weichselian represent glacial advances into northern Denmark. The first event occurred just after deposition of the regional foraminiferal zone N2 (late MIS 4), and the second event in the middle part of zone N1 (early MIS 3). Zone N1 is succeeded by a series of non-marine units deposited during the sea-level lowstand of the Weichselian maximum glaciation (late MIS 3 and MIS 2), including deeply incised tunnel valleys, which have been refilled with non-marine sediments during the Late Weichselian. Vendsyssel was inundated by the sea again during the Late Weichselian, at c. 18 kyr BP. Subsequently, the marine conditions were gradually changed by forced regression caused by local isostatic uplift, and around the Weichselian-Holocene transition most of Vendsyssel was above sea level. A continuous deposition across the Late Weichselian-Holocene boundary only occurred at relatively deep sites such as Skagen. The environmental and climatic indications for Vendsyssel are in accordance with the global sea-level curve, and the Quaternary record is correlated with the oxygen isotope record from the NorthGRIP ice core, as well as the marine isotope stages. (Less)

Changes in palaeoenvironments over the last 15000 years have been documented by a high-resolution diatom record of core 17940 from the northern slope of the South China Sea. Four diatom assemblage zones, each characterized by different diatom components, are distinguished by cluster analysis. T. nitzschioides var. parval (T nitzschioides + T nitzschioides var. parva) (Tnp/ (Tnp + Tn)) and the brackish-littoral species, used as the proxies for temperature and salinity, are compared with previously published sea-surface temperature (FP-12E-SSTw) and sea-surface salinity (SSS) data from the same core and with the Dongge Cave delta(18)O record. The Bolling-Allerod warm phase, the Younger Dryas cold event, the Holocene Climate Optimum and three Holocene cooling events (7150-6250, 4150-3450 and 1800-1350 cal. yr BP) are clearly distinguished by changes in the abundance of the brackish-littoral species and/or in Tnp/(Tnp +Tn) data. A marked increase in the abundance of the coastal species Paralia sulcata during the interval 11150-8050 cal. yr BP indicates a strong coastal water influence, probably due to both enhanced freshwater discharge from the Pearl River and the opening of the Taiwan Strait This palaeoceanographic change might be caused partly by climate-induced sea-level lowering during the late Pleistocene and the early Holocene. The palaeoceanography during most of the Holocene appears to be primarily controlled by fluctuations in the East Asian summer monsoon intensity. (C) 2009 Elsevier B.V. All rights reserved.

Pluri-annual proxy records of marine sediment cores from the Tagus Prodelta off Lisbon, Portugal, have been generated to gain insight into the climatic and hydrographic changes in the area during the twentieth century. The study includes benthic and planktonic foraminiferal faunas and the stable isotopic composition of one benthic ( Uvigerina celtica) and two planktonic ( Globigerina bulloides and Globorotalia inflata) foraminiferal species. Sea bottom and surface water temperatures were estimated based on the δ18O values of these species and compared with instrumental data. The foraminiferal fauna and the isotope-based temperature record indicate increasing temperatures throughout the last century. The immigration of a new species, Saidovina karreriana, to the area around 100 years ago indicates changes in the trophic conditions and water mass properties, which are probably at least partly due to anthropogenic pollution.

A high-resolution diatom record from core MD99-2275 reveals a series of palaeoceanographic changes on the North Icelandic shelf since about 9000 cal. yr BP. The influence of relatively warm high-salinity Atlantic water-masses of the IC was strong in the study area during the Holocene Climate Optimum (8760 (base of record) to c. 5300 cal. yr BP) and peaked between c. 8000 and 7000 cal. yr BP. There is a general cooling trend from c. 7000 cal. yr BP to the present, which is indicated by an increase in the influence of cold Polar water-masses from the EGC and the EIC and a decrease in the influence of the IC. A major change in diatom assemblages at around 5300 cal. yr BP indicates a palaeoceanographic shift on the North Icelandic shelf in the mid-Holocene. In addition, several abrupt palaeoceanographic changes are distinguished. Enhanced influence of Polar waters is reflected during the intervals 8120–8000, 6650–6100, 4300–4100, 3000–2700, 1300–1100 and 600–200 cal. yr BP. The palaeoceanographic indication of the diatom record of core MD99-2275 is consistent with the indication of other environmental parameters from the same core, such as benthic and planktonic foraminifera as well as magnetic properties, and the results are also consistent with palaeoclimatic records from adjacent areas around Iceland and in the North Atlantic region.

Isoleucine epimerization (alle/Ile) ratios have been measured on foraminiferal tests from interglaical sites in the southern North Sea region. In order to evaluate the possibilities of this amino acid method on benthic foraminifera, sites were chosen from areas where the stratigraphy was already well known. The study demonstrates that the isoleucine epimerization reaction in benthic foraminifera can be used for correlation and as a means of relative age estimation within a limited geographic area. Previous suggestions of a Holsteinian age for the Rugȧrd, Tornskov, and Wacken sites are supported for the Kås Hoved site. The age of most presumed Eemian sites is supported by the amino acid results; the Reighton site also seems to belong in this interglacial.

A new stratigraphic framework is proposed for the Quaternary of a portion of central West Greenland, based primarily on faunal and geochronologic studies of shallow shelf deposits. Twenty‐four occurrences of pre‐Holocene deposits were already known in West Greenland and data from 18 new sites are presented, together with new information on some of the previously described localities. Four pre‐Holocene marine events are described. The interglacial Ivnaarssuit and Nordre Laksebugt marine events are considered to be Middle Pleistocene in age. The interstadial Laksebugt marine event is considered to be late Middle Pleistocene, whereas the Svartenhuk marine event is correlated with the last interglacial. For the last glacial period an extensive ice shelf is proposed west of Disko. The oldest postglacial deposits are dated at 10,470 ± 130 14C‐years BP.

Foraminifera from four boreholes through Quaternary deposits at Roar, Skjold and Dan in the central North Sea have been examined. Shallow marine Eemian deposits were represented over the whole area, and at Roar marine deposits from an older glacial period were found below the Eemian. A glaciolacustrinc sequence occurred above the Eemian in all the boreholes, and at Roar this unit was succeeded by marine sediments containing arctic to boreo-arctic foraminiferal faunas. Both the non-marine and overlying marine units are referred to the Weichselian. Marine Flandrian deposits occur in the upper part of the borings and the faunal succession through this sequence is described.