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A series of Quaternary mass transport deposits (MTDs) with a total areal extent of ~11,000 km 2 and a conservative volume estimate of ~1035 km 3 are observed in the Pearl River Mouth Basin (PRMB), northern South China Sea (SCS), based on integrated analysis of extensive 2-D/3-D seismic data, multibeam bathymetric data and ODP/IODP wells. Unlike other large MTDs worldwide, the MTDs in this study are not directly sourced from slopes built on major deltaic depositional systems. Moreover, they are remarkable in that the whole PRMB is a giant debris flow corridor that has transected a broad subsided continental margin. The MTDs in this study have a large evacuation zone on the slope and a depositional zone in the ocean basin connected by a narrow pathway. Six events of MTDs (MTDa - MTDd on the slope and MTDo1 - MTDo2 in the ocean basin) have been identified as being separated by basal erosional surfaces defined by strong negative seismic reflections. Similar ages and volumes (depleted volume of MTDb on the slope and the depositional volume of MTDo2) suggest that MTDo1 and MTDo2 correlate with MTDa and MTDb, respectively. The major factor controlling the occurrence of slope failures is argued to be the presence of a key reflection package. This package is interpreted to consist of gas-charged, coarse-grained sediments deposited during a relative lowstand of sea level, overlain by a unit of fine-grained sediments. Other contributing factors that influenced the morphology and position of the MTDs include the presence of free gas, normal faulting in the slope sediments, and seafloor relief related to igneous activity. From MTDd to MTDb, slope failures are shown to have retrogressed upslope with a decreasing time interval between events. The events, dimensions, susceptible factors and formation processes of slope failures in the study area are demonstrated for the first time in the petroliferous basin of northern SCS. Their recognition is important for geo-hazard assessment (e.g. tsunami) in this area. Moreover, this study highlights that the lithostratigraphy of the slope succession, especially the coarse-grained sediments in the deepwater area, can be an important component for the occurrence of slope failures, and may be a key factor in slope stability on other continental margins too. [ABSTRACT FROM AUTHOR]

The late Quaternary paleoceanography and paleoenvironment of the South China Sea (SCS) have been well reconstructed over the last decade. In contrast, the provenance of the terrigenous sediments that have accumulated in the northwestern continental shelf mud area remains enigmatic. This study investigated the provenance of these sediments and the paleoenvironmental changes archived in Core X2 via the analysis of geochemical elements, grain size, and accelerator mass spectrometry (AMS) 14 C ages. Based on the upper continental crust (UCC)-normalized REE patterns and REE fractionation parameters, southwestern and western Taiwanese rivers and the Pearl River were identified as the main sources of the fine-grained sediment deposited in the northwestern shelf mud area off Hainan Island. This finding further confirms the long-distance transport (> 1000 km) of fine-grained sediment from Taiwanese rivers to the northern SCS shelf and slope. Obvious changes in the grain size and Chemical Index of Alteration (CIA) record occurred at approximately 4.0 cal kyr BP and were likely caused by increased Hainan Island inputs due to sea level changes. [ABSTRACT FROM AUTHOR]

In central eastern Anatolia which is located between Eurasia and Africa, the study of basin developments between late Eocene and early Miocene is of great importance for understanding the process of the closure of the Neo-Tethys Ocean and the formation of strike-slip faults and regional uplift. To study these, three basins were selected: the Sivas-Erzincan, Gürün-Akkisla-Divrigi (GAD), and Malatya basins. The study proposes that the opening of the GAD basin played a key role in the formation of the Ecemis fault, which started developing at the end of early Miocene, and in mountain uplift. All these basins are situated on continental blocks and oceanic crust, arranged from north to south as the Sakarya continent, the Izmir-Ankara-Erzincan ocean (Northern Neo-Tethys), the Kirsehir continent, the inner Tauride ocean, the Munzur-Binboga block, the Maden (=Berit) ocean, the Bitlis-Pütürge block, the Çüngüs ocean and the Arabian continent. The findings indicate that late Eocene-early Miocene successions in these basins were not deposited in foreland basins formed in front of the thrust faults associated with the closure of the ocean, as stated in previous studies. Rather, they were deposited in forearc and backarc basins related to the subduction which was effective until the end of early Miocene. The Sivas-Erzincan and Malatya basins, located on the inner Tauride and Maden (=Berit) oceans, were forearc basins, while the GAD basin situated on the Munzur-Binboga block was a backarc basin. These basins have parallel developments up to the end of early Miocene. While marine sediments were deposited in the Malatya and Sivas-Erzincan basins between late Eocene and early Miocene, terrestrial units began to settle in the GAD basin from the late Eocene and the deposition there is continuous until the end of the early Miocene. Collision of the Arabian and the Anatolian plates at the end of early Miocene (16-18 Ma) produced the left-strike slip Ecemis fault zone, which caused the lateral slip of sedimentary units in the Sivas-Erzincan and GAD basins over hundreds of kilometers. This event produced the first westward tectonic escape of the Anatolian plate prior to the north Anatolian fault (NAF) and the east Anatolian fault (EAF). The Gürün region located in the GAD basin was exhumed in late Miocene and this basin was broken. The Gürün region, which remains on the rising part of the Munzur-Binboga block, is not a different basin as stated earlier, but it is a part of the GAD basin, representing the central part of the GAD basin lake, as indicated by the fine grained deposits (limestones and clay) that occur in the Gürün area. [ABSTRACT FROM AUTHOR]

Marine sediments record paleoenvironmental changes over time through variations in major and trace element concentrations. The main objective of this paper is to review such changes in the Mediterranean Sea basins over the last 20 ka, using the inorganic chemistry and mineralogy of marine sediment records. Elemental ratio proxies that are mostly used are discussed, and the uncertainties involved in using them for paleoclimate and paleoceanographic reconstructions are evaluated. The focus on the Mediterranean region is based on the sensitivity of this region to global climate changes due to its semi-enclosed nature. The elemental ratios that have been particularly useful for reconstructing terrigenous inputs into the Mediterranean have been Ti/Al and Zr/Al ratios as proxies for eolian dust input, and Mg/Al, K/Al and Rb/Al ratios as proxies for fluvial input. Redox sensitive elements (e.g., U, Mo, V, Co, Ni, Cr) have provided reliable reconstructions of oxygen conditions at the time of deposition. Some of these elements are also particularly susceptible to post-depositional remobilization and record diagenetic processes instead of the original environmental signatures. Regarding productivity fluctuations, most of the paleoproductivity reconstructions are based on the abundance of barite and Ba excess algorithms. The biogeochemistry of Ba is, however, not fully understood and mechanisms for barite precipitation in the water column are not yet known. Two case studies are presented: the eastern Mediterranean sapropel S1 (deposited between 10.8 and 6.1 cal ka BP) and the westernmost Mediterranean paleoclimate record over the last 20 ka. [ABSTRACT FROM AUTHOR]

Abstract: Planktic foraminiferal assemblages in a composite section from two cores (MD06-2989/2986) off the west coast of New Zealand''s South Island (42–43.5°S) provide a 1myr (MIS 31–1) sea-surface temperature (SST) record (~3–4kyr resolution) in the Tasman Sea. A significant overall faunal change occurred near the end of the mid-Pleistocene Climate Transition (MPT) at ~600ka (MIS 15). Mean annual SSTs were estimated using the Artificial Neural Network (ANN) method. Glacial–interglacial (G–I) cycles in the MPT had ~9°C SST range, whereas in the post-MPT SST range was ~6–7°C. The SST and faunal changes imply that the Subtropical Front (STF) migrated ~6° in latitude to lie just north of the sites in MPT glacials (MIS 28–16), but only migrated 3–5° north in post-MPT glacials. These G–I latitudinal migrations of the STF west of New Zealand contrast with the situation east of New Zealand, where migrations of both the STF and Subantarctic Front were prevented by the Chatham Rise and Campbell Plateau. Subtropical Water is inferred to have only flowed around the south of New Zealand (as it does today) during MIS 11 and the Late Pleistocene–Holocene (MIS 5–1). [Copyright &y& Elsevier]

Abstract: Submarine canyons can efficiently drain sediments from continental margins just as river systems do in subaerial catchments. Like in river systems, submarine canyons are often arranged as complex drainage networks that evolve from patterns of erosion and deposition. In the present paper we use a morphometric analysis of submarine canyon-channel long-profiles to study the recent sedimentary history of the Valencia Trough turbidite system (VTTS) in the NW Mediterranean Sea. The VTTS is unique in that it drains sediment from margins with contrasting morphologies through a single “trunk” conduit, the Valencia Channel. The Valencia Channel has been active since the late Miocene, evolving in response to Plio-Quaternary episodes of erosion and deposition. The integrated analysis of long-profiles obtained from high-resolution bathymetric data across the entire turbidite system shows evidence for transient canyon incision in the form of knickpoints and hanging tributaries. Multiple factors appear to have triggered these periods of incision. These include a large debris flow at 11,500yrBP that disrupted the upper reaches of the VTTS and glacio-eustatic lowstands that forced shifting of sediment input to the VTTS. Based on these inferences, long-term time-averaged incision rates for the Valencia Channel have been estimated. The evidence we present strongly suggests that Foix Canyon has played a key role in the drainage dynamics of the VTTS in the past. This study builds conceptually on a recent modeling study that provides a morphodynamic explanation for the long-term evolution of submarine canyon thalweg profiles. The procedure and results from this work are of potential application to other submarine sediment drainage systems, past and present, including those containing mid-ocean type valleys like the Valencia Channel. [Copyright &y& Elsevier]

Abstract: The early Quaternary stratigraphic and geographic distribution of teleostean fishes in the Ionian Sea (eastern Mediterranean) is examined based on the fossil otolith record. Through comparison between the western and the eastern Ionian early–middle Pleistocene deep-sea ichthyofauna, the stratigraphic distributions of nineteen taxa are revised. A new method of assemblage analysis is attempted, in order to discern the palaeoceanographic conditions prevailing at this time. The relative contributions of tropical, subtropical, temperate, and subpolar taxa to the surface, intermediate, and deepwater fish palaeofauna are calculated, using fossil material from Akrotiri (Kephallonia Island, Greece), Gerakas (Zakynthos Island, Greece) and Montalbano Jonico (Italy) sections, which span the Gelasian–Ionian time interval. Eleven distinct phases in the Ionian Sea palaeoceanographic evolution are distinguished, from prior 1.95Ma to 0.61Ma. Furthermore, a case study is conducted, to test the hypothesis that palaeoichthyofauna can be used to draw conclusions regarding the palaeocirculation patterns and their variability. In the Ionian Sea, the local production and/or Atlantic origin of the deep cold waters is registered already during the Gelasian. The presence of oceanic fish in the eastern Ionian can be explained by the existence of a strong anticyclonic gyre in the area during the early Quaternary, further indicating that the basin''s geometry exhibited sufficient bathymetric variation to allow for the activation of the gyre. [Copyright &y& Elsevier]

Abstract: The morphology and distribution of submarine landforms in Hinlopen Trough, Northern Svalbard margin, and the upper continental slope beyond, are investigated using swath-bathymetric data, together with side-scan sonar, acoustic profiler records and sediment cores. Sun-illuminated images reveal a number of landform assemblages on the sea floor of Hinlopen Trough and confirm that this depression was occupied by an ice stream during the Late Weichselian glaciation around 20ka before present. The geomorphology of the inner-shelf is characterised by bedrock drumlins and ice-sculpted bedrock. There is a middle-shelf transition from a rock bed to an unconsolidated sedimentary bed that contains highly-attenuated drumlins and megaflutes formed within a dark grey, matrix-supported diamict, interpreted as subglacial till. Outer-shelf landforms are mainly iceberg ploughmarks. The geomorphological imprint identified from Hinlopen Trough is similar to that of many former ice streams; the trough is dominated by elongate landforms orientated parallel to the inferred flow direction and is lacking in transverse features indicative of inter-ice stream locations. A characteristic down-flow progression in landform elongation is also observed, suggesting an increase in ice velocity across the continental shelf. The lack of grounding-zone features imaged from swath-bathymetric data implies that deglaciation was probably rapid within the trough. A large depositional fan exists on the upper continental slope beyond the trough, characterised by debris flow deposits relating to the down-slope transport of glacigenic sediment. Order of magnitude calculations of the volume of glacigenic sediment on the continental slope indicate that the ice stream provided high rates of debris delivery of around 5–7.5m/ka. This suggests that Hinlopen Trough ice stream represented a major route for the transfer of ice and debris to the Hinlopen Fan on the northern continental margin of Svalbard during the Late Weichselian glaciation. [Copyright &y& Elsevier]

Changes in the abundance of selected planktic foraminiferal species and some sedimentological parameters at ODP site 728A were examined to understand the fluctuations in the surface productivity and deep sea oxygenation in the NW Arabian Sea during last ∼540 kyr. The increased relative abundances of high fertility taxa, i.e., Globigerinita glutinata and Globigerina bulloides mainly during interglacial intervals indicate intense upwelling. Strong SW summer monsoon probably increased the upwelling in the western Arabian Sea during interglacial intervals and caused high surface productivities due to the lateral transport of eutrophic waters. Most of the glacial periods (i.e., MIS 2, 4, 6, 8 and 12) are characterized by higher relative abundances of Neogloboquadrina pachyderma and Neogloboquadrina dutertrei associated with Globigerinoides ruber. The more stratified condition and deep mixed layer due to increased NE winter monsoon are mainly responsible for the higher relative abundances of N. pachyderma during glacial periods. Some of the glacial intervals (i.e., MIS 6 and 8) are also characterized by pteropod spikes reflecting deepening of aragonite compensation depth (ACD) and relatively less intense oxygen minimum zone (OMZ) in this region due to deep sea mixing and thermocline ventilation, and relatively less intense surface productivity during winter monsoon. The interglacial periods are largely devoid of pteropod shells indicating more aragonite dissolution due to increased intensity of OMZ in the northwestern Arabian Sea. In general, the interglacial periods are characterized by low sediment accumulation rates than the glacial intervals. On an average, the total biogenic carbonate percentages were higher during interglacial and during periods of higher surface productivity. Most terrigenous material was trapped on shelf during intervals of high sea level stands of interglacial, whereas more erosion of shelf increased the sedimentation rates during glacial periods. In addition, the fragmentation record may be the result of changes in intensity and vertical distribution of the OMZ with time. During glacial intervals, the lower boundary of the OMZ probably was in a shallower position than during interglacial periods, when dissolution increased as a result of higher organic production. The higher rates of sinking organic matter result into a stronger OMZ as oxygen is used to disintegrate the organic matter. This process lowers the p of water which results into increased dissolution of calcium carbonate. [ABSTRACT FROM AUTHOR]

Abstract: In order to understand the glacial to interglacial fluctuations in pteropod preservation and productivity during the late Quaternary (∼54ka BP to present), we investigated pteropod, organic carbon (Corg) and Globigerina bulloides abundance in a deep sea core from the western Andaman Sea. Pteropod abundance and preservation is similar to the “Indo-Pacific carbonate preservation type”, showing better preservation during glacial and poor preservation during interglacial periods. The core site appears to have remained below the aragonite compensation depth (ACD) throughout the Holocene, indicated by the total absence of pteropods. Maximum abundance and good preservation of pteropods was observed during stadials such as Younger Dryas (YD), Heinrich Events (HEs) and Last Glacial Maxima (LGM) indicating weaker oxygen minimum zone (OMZ) and deeper ACD. Furthermore, the high relative abundance of mesopelagic pteropods over epipelagic forms suggests a well ventilated water column with weak OMZ particularly during LGM, apparently driven by intense winter monsoon. Increased monsoon-driven productivity was observed during 45–40ka, of early Marine Isotope Stage 2 (MIS 2, 24–22ka), Bølling/Allerød (B/A; 15–13.5ka), YD and late Holocene as evidenced by Corg content and G. bulloides. Enhanced pteropod preservation of H1 associated with low Corg content and G. bulloides suggests that reduced monsoonal driven productivity might have influenced pteropod preservation. Deglacial preservation spike in the Andaman Sea is consistent with other northern Indian Ocean records and elsewhere outside the Indian Ocean implying the event is global in nature, marked by deepening of ACD probably driven by enhancement of winter monsoon on local and changes in intermediate water circulation on regional scale. [ABSTRACT FROM AUTHOR]

Abstract: African dust additions explain the origin of terra rossa soils that are common on the carbonate-platform island of Mallorca, Spain. Mineralogical and geochemical analyses indicate that Quaternary carbonate eolianites on Mallorca have a very high purity, usually composed of more than 90% carbonate minerals (calcite, dolomite, and aragonite). In contrast, terra rossa soils developed on these eolianites have lower carbonate contents and contain higher concentrations of quartz and other silicates. Analyses of immobile trace elements indicate that the non-carbonate fractions of the eolianites have distinctive Zr/Hf, La/Yb, Cr/Sc and Th/Ta values that differ from the superjacent terra rossa soils. These observations indicate that even if sufficient dissolution of the eolianite had taken place to create the soils by residual accumulation, immobile element ratios in the soils require an external source. However, Zr/Hf, La/Yb, Cr/Sc and Th/Ta values in the soils fall within the range of values for these element ratios in African dust collected on Barbados and mainland Spain. We conclude that the silicate fractions of terra rossa soils on Mallorca are derived mainly, though not wholly, from far-traveled African dust, and this process may explain the origin of other terra rossa soils found in southern Europe. [ABSTRACT FROM AUTHOR]

The article presents a study on the water salinity history during the late Quaternary period in the Pearl River estuary in China. The study indicates the major factors that affect the estuary's water salinity including freshwater discharge, sea level, and deltaic shoreline movement. It demonstrates the advantage of salinity reconstructions in improving reconstruction quality in estuaries and observing salinity values.

Abstract: The current study broadens the biodiversity information available for the Black Sea and neighbouring regions and improves our knowledge about the polychaete biogeographic patterns to be discerned in them. There appears to be a well-defined zoogeocline from the Marmara Sea and Bosphorus Strait to the inner parts of the region (Azov Sea), depicted both as a multivariate pattern and in terms of species (or taxa) numbers. The emergent multivariate pattern complies, to a certain extent, with views: three main sectors can be defined in the basin: (a) Prebosphoric, (b) the Black Sea and, (c) the Azov Sea, whereas the Bosphorus Strait and Marmara Sea show less faunal affinities with the afore-mentioned sectors. Patterns derived both from the cosmopolitan and Atlanto-Mediterranean species closely follow the one coming from the polychaete species and genera inventories. As a general trend, species numbers decrease along with the decrease in salinity towards the inner parts of the region. The trend is homologous to that seen in the benthic invertebrate inventories of all the major European semi-enclosed regional seas. Salinity and food availability appear to be the dominant abiotic factors correlated, though weakly, with the various patterns deriving from the taxonomic/zoogeographic categories. With the exception of the Anatolia, polychaete inventories from all sectors appear to be random samples of the total inventory of the region, in terms of taxonomic distinctness values. Therefore, these sectoral inventories can be used for future biodiversity/environmental impact assessment studies. A massive invasion of Mediterranean species after the opening of the Black Sea, in the lower Quaternary period, appears to be the likely biogeographic mechanism through which the old Sarmatic fauna was almost completely replaced by species of marine origin. [Copyright &y& Elsevier]

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A benthic microfaunal record from the equatorial Atlantic Ocean over the past four glacial-interglacial cycles was investigated to understand temporal dynamics of deep-sea latitudinal species diversity gradients (LSDGs). The results demonstrate unexpected instability and high amplitude fluctuations of species diversity in the tropical deep ocean that are correlated with orbital-scale oscillations in global climate: Species diversity is low during glacial and high during interglacial periods. This implies that climate severely influences deep-sea diversity, even at tropical latitudes, and that deep-sea LSDGs, while generally present for the last 36 million years, were weakened or absent during glacial periods. Temporally dynamic LSDGs and unstable tropical diversity require reconsideration of current ecological hypotheses about the generation and maintenance of biodiversity as they apply to the deep sea, and underscore the potential vulnerability and conservation importance of tropical deep-sea ecosystems. [ABSTRACT FROM AUTHOR]

Abstract: The coastal aquifer of the Plio-Quaternary delta sediment deposits of the Vélez river (province of Málaga, Spain) presents a highly irregular basement morphology and widely varying fill thickness (10–80 m between neighbouring sectors). The basin, which is tectonically controlled, is filled with lutite facies alternating with channel-filling rudites. This detrital aquifer is affected by seasonal seawater intrusion–extrusion processes due to increasing withdrawal of groundwater for human consumption and irrigation during dry periods. A study was performed to improve the hydrogeological knowledge of this coastal aquifer system. The study examined the morphology of the impervious substratum, the facies distribution and the position of the seawater wedge. For this purpose, an Electrical Resistivity Tomography (ERT) geophysical technique was used and the tomographic data were calibrated using geological observations and borehole studies. An analysis was carried out to compare the direct information obtained from the 35 boreholes with the indirect data corresponding to the four electrical tomography profiles. In the study, over 9660 resistivity data points were processed. The ERT profiles perfectly corroborated the information derived from the boreholes. The profiles made it possible to detect thickness changes, lithological changes and the presence of faults. Moreover, from a hydrogeologic standpoint, this research technique is capable of detecting the position of the phreatic level and, in coastal aquifers such as the one examined in this study, the possible horizontal or vertical penetration of seawater intrusion. Therefore, the electrical geophysical prospecting based on ERT can be highly useful in areas lacking sufficient geological information and/or mechanical borehole data. [Copyright &y& Elsevier]

Abstract: The chemical composition of shells of the planktonic foraminifer Globigerinoides ruber (white) is frequently used to determine past sea surface conditions. Recently, it has been shown that arbitrarily defined morphotypes within this species exhibit different chemical and isotopic signatures. Here, we investigate the occurrence through time and in space of morphological types of G. ruber (white) in late Quaternary and Holocene sediments of the central and the eastern Mediterranean Sea. In 115 samples representing two distinct time intervals (MIS 1–2 and MIS 9–12) at ODP Site 964 and the piston core GeoTü-SL96, we have defined three morphological types within this species and determined their relative abundances and stable isotopic composition. A quantitative analysis of morphological variation within G. ruber (white) in four samples revealed that the subjectively defined morphotypes occupy separate segments of a continuous and homogenous morphospace. We further show that the abundance of the morphotypes changes significantly between glacials and interglacials and that the three morphotypes of G. ruber show significant offsets in their stable isotopic composition. These offsets are consistent within glacial and interglacial stages but their sign is systematically reversed between the two Sites. Since the isotopic shifts among the three G. ruber morphotypes are systematic and often exceed 1‰, their understanding is essential for the interpretation of all G. ruber-based proxy records for the paleoceanographic development of the Mediterranean during the late Quaternary. [Copyright &y& Elsevier]

Abstract: Sediment core HLY0503-8JPC raised by the HOTRAX''05 expedition from the Mendeleev Ridge was analyzed for multiple lithological, paleontological, and stable-isotopic proxies to reconstruct paleoceanographic conditions in the western Arctic Ocean during the Late Quaternary. The core, extensively sampled in the upper 5 m, reveals pronounced changes in sedimentary environments during the ca. 250 kyr interval encompassing Marine Isotopic Stages (MIS) 1 to 7. An estimated average resolution of 500 yr/sample, at least for the last glacial cycle including the last interglacial, provides more detail than seen in other sedimentary records from the western Arctic Ocean. The age control is provided by 14C and amino acid racemization measurements on planktonic foraminifers and correlations with the stratigraphy developed for the central Lomonosov Ridge and with glacial events at the Eurasian Arctic margin. Cyclic variations in lithology combined with foraminiferal abundance and stable-isotopic composition indicate profound changes in hydrographic and depositional environments between interglacial-type and glacial-type periods apparently reflecting a combination of 100-kyr and precessional time scales. This periodicity is complicated by abrupt iceberg- and/or meltwater-discharge events with variable (Laurentide vs. Eurasian) provenance. The proxy record from the interval identified as the last interglacial (MIS 5e), which may aid in understanding the future state of the Arctic Ocean, indicates low ice conditions and possibly enhanced stratification of the water column. [Copyright &y& Elsevier]

Abstract: We present a detailed study of glacial/interglacial deep sea benthic ostracod assemblage variability at IODP Site U1314 (subpolar North Atlantic) in relation to the history of ice-rafting events and changes in deep ocean circulation over the past 170 ky. Our records of ostracod diversity, abundance and dissolution and sediment properties (IRD and CaCO3) show an excellent correspondence to high amplitude orbital and millennial variability observed in the climate records (δ13C and δ18O) from neighboring deep water sites, suggesting that the benthic meiofauna fluctuates synchronously with the prevailing oceanographic conditions (surface ocean conditions, deep ocean circulation and water temperature and food flux). Krithe (dominant), Argilloecia and Cytheropteron are the most abundant and diverse genera in association with Rockallia enigmatica. Three ostracod assemblages are recognized. The genera Pennyella, Argilloecia, Pelecocythere, Ambocythere, Pseudobosquetina, Bradleya and Nannocythere are associated with interglacials and interstadials, and possibly reflect increased flux of food to the sediments and more vigorous NADW formation. A transitional assemblage composed of species of Cytheropteron, Xestoleberis and Eucythere is restricted to climatic transitions and indicate moderate environmental conditions and seasonal productivity. A glacial/stadial assemblage is characterized by a temporal predominance of either intermediate-depth and shallow water Arctic/subarctic species (belonging to Cytheropteron, Polycope, Pedicythere, Swainocythere, Cluthia, Heterocyprideis, Elofsonella and Finmarchinella) or abyssal North Atlantic ostracods (Bythocythere, Dutoitella, Bathycythere and Bythocypris). The influx of high latitude taxa can be partially explained by ice-rafting, but may also represent a shift of the location of intermediate and deep water convection to the area south of Iceland. Therefore the combination of species characteristic of different watermasses during glacials may reflect shifts in the influence of high nutrient southern source water (e.g. AABW) vs. low nutrient GNAIW during glacials. [Copyright &y& Elsevier]

Abstract: The Norwegian Channel Ice Stream (NCIS) is one the defining features of the Fennoscandian icesheet. Still little is known of the detailed dynamics of this ice stream in relation to regional changes in ice cover, paleoceanographic and climatic changes. Sedimentological data from core MD99-2283 in combination with seismic data allow a detailed chronological reconstruction of the outbuilding of the margin and the ice extent in southern Scandinavia through the last 150ka. An integrated stratigraphy of the margin is presented and compared to the glacial history. Changes in the regional ice cover are reflected in the accumulation rates, the clay mineralogy, the coarse chalk fraction and the number of IRD >2mm in core MD99-2283, while the sedimentation on the North Sea Fan as derived from seismic data provides direct evidence for the glacial activity at the shelf edge. Tentative evidence was found for two Early Weichselian glacial advances in southern Scandinavia and possibly Scotland at around 110 and 80kaBP. From 42calkaBP the ice cover expanded in southern Fennoscandia and led to increased deposition on the margin and the occurrence of local melt water outbursts. Significantly increased accumulation rates, coarse chalk, local meltwater output and smectite occur during the ice expansion in the North Sea from around 34calkaBP. The main outbuilding phase of the NSF during the last glacial cycle occurred after 30calkaBP. From around 24calkaBP the NCIS became highly active and advanced at least three times prior to the final retreat from the shelf edge around 19.0calkaBP. [Copyright &y& Elsevier]

Abstract: Measurements of diatom oxygen isotopes (δ 18Odiatom) hold the potential to provide an important additional source of palaeoceanographic information in regions depleted in carbonates. However, despite analyses of δ 18Odiatom being carried out since the 1970s and the increasingly widespread use of δ 18Odiatom in palaeolimnology since the 1990s, to date only a handful of studies have applied δ 18Odiatom in marine reconstructions. Here the historical development and current state of affairs concerning the usage of δ 18Odiatom in palaeoceanography is reviewed. This includes a summary of: [1.] sample purification and analytical techniques for δ 18Odiatom; [2.] existing palaeoceanographic reconstructions with an emphasis on sites at which both diatoms and foraminifera have been analysed for δ 18O; [3.] uncertainties associated with δ 18Odiatom including the presence of isotope vital effects and secondary isotope exchanges; [4.] a review of the current and future developments required to improve the reliability of δ 18Odiatom based reconstructions in palaeoceanography. [Copyright &y& Elsevier]

The Mackenzie Trough provides a high resolution signal for paleoceanography as a result of high sedimentation rates at the mouth of the Mackenzie River. Three cores were collected along a transect covering a depth range of 58–671 m and the time period of the last 11 500 cal BP. Prior to the last ~10 000 cal BP, the distal core is characterized by laminated sediment and a foraminiferal fauna of Arctic Bottom Water calcareous species and abundant planktic foraminifera suggesting little freshwater runoff and (or) perennial sea-ice cover. This occurs at a similar time as laminated sediments from the west of this site, which have been suggested to be part of the Lake Agassiz flood outburst and (or) cold period. If this outburst occurred, the very positive oxygen isotope values from our core (PC3; >+3.0 ppm) indicate that it did not flow through the Mackenzie Trough. After 9000 cal BP, the faunas in the three cores differ because of timing and different water depths. However, it is possible to see a progression of cold saline water prior to 10 000 cal BP, with a freshening of surface water after 10 000 cal BP where tintinnids (brackish water ciliates) occur with incursions of deep water Arctic calcareous species to ~3000 years BP. A sequence of mixed faunas appears as sea ice returns, at least periodically in the last 3000 cal BP; but (in core PC2 only) a return to more sea ice is recorded by both foraminifera and dinocysts in the last few hundred years. La fosse du Mackenzie fournit un signal à haute résolution pour la paléocéanographie en raison des taux élevés de sédimentation à l’embouchure de la rivière Mackenzie. Trois carottes ont été prélevées le long d’un transect couvrant une plage de profondeurs de 58 à 671 m; la période de temps couvre les derniers 11 500 années calendaires avant le présent (années cal. BP). Avant les derniers ~10 000 années cal. BP, la carotte distale est caractérisée par des sédiments laminés et une faune de foraminifères d’espèce calcaire des eaux du fond de la mer Arctique et les nombreux planctons foraminifères suggèrent peu d’écoulement d’eau douce et (ou) un couvert permanent de glace de mer. Cela se produit en même temps qu’une déposition de sédiments laminés à l’ouest de ce site; ces sédiments feraient partie du débordement de l’inondation et (ou) de la période froide du lac Agassiz. Si ce débordement a eu lieu, les valeurs très positives de l’isotope de l’oxygène de notre carotte (PC3; >+3,0 ppm) indiquent qu’il ne s’est pas écoulé à travers la fosse du Mackenzie. Après 9000 années cal. BP, les faunes dans les trois carottes diffèrent en raison des moments de déposition et des profondeurs d’eau différentes. Il est toutefois possible de voir une progression de l’eau froide saline avant 10 000 années cal BP. Après 10 000 années cal. BP, on note un adoucissement de l’eau de surface; en effet, des tintinnides (un cilié planctonique d’eau saumâtre) se retrouvent mélangés à des espèces calcaires d’eau profonde de l’Arctique jusqu’à ~3000 années BP. Une séquence mixte de faunes apparaît au retour de la glace de mer, du moins périodiquement, au cours des dernières 3000 années cal. BP. Cependant, un retour à plus de glace de mer est enregistré dans les foraminifères et les dinokystes au cours des quelques dernières centaines d’années (seulement dans la carotte PC2). [ABSTRACT FROM AUTHOR]

Abstract  We show the magnetic model of the Selli-Vavilov region. The Selli Line is known as the northwestern edge of the southern Tyrrhenian Basin. The tectonic evolution of the Tyrrhenian Basin is dominated by a Tortonian-Quaternary extension through the eastward movement of the Apennine subduction system. This migration has generated a diffuse stretching of the continental crust with the emplacement of new oceanic material. This latter occurred in several localized zones where the eastward retreating of the Ionian subduction system produced a strong depletion of the crust with formation of basins and correlated spreading. Nowadays the presence of oceanic crust is confirmed through direct drilling investigation but a complete mapping of the oceanic crustal distribution is still lacking. The Selli-Vavilov region shows a differentiated crustal setting where seamount structures, the oceanic basement portions and continental crust blocks are superimposed. To this aim, a 2D inversion of the magnetic data of this region was conducted to define buried structures. The magnetic susceptibility pattern was computed by solving the least squares problem of the misfit between the predicted and real data for separated wavebands. This method produced two 2D models of the high and low frequency fields of the Selli-Vavilov region. The two apparent susceptibility maps provide different information for distinct ranges of depth. The results of the inversions were also combined with seismic data of the Selli region highlighting the position of the highly magnetized buried bodies. The results confirm a role for the Selli Line as a deep crustal boundary dividing the Sardinian passive domain from the easternmost active region where different oceanic structures are located. The Selli Line has worked as a detachment fault system which has moved eastward. Finally, the Selli-Vavilov region may be interpreted as a tectonic result due to a passive asymmetrical rift occurred between the Tortonian and Pliocene. [ABSTRACT FROM AUTHOR]

Abstract: Uniquely in the Southern Hemisphere the New Zealand micro-continent spans the interface between a subtropical gyre and the Subantarctic Circumpolar Current. Its 20° latitudinal extent includes a complex of submerged plateaux, ridges, saddles and basins which, in the present interglacial, are partial barriers to circulation and steer the Subtropical (STF) and Subantarctic (SAF) fronts. This configuration offers a singular opportunity to assess the influence of bottom topography on oceanic circulation through Pleistocene glacial – interglacial (G/I) cycles, its effect on the location and strength of the fronts, and its ability to generate significant differences in mixed layer thermal history over short distances. For this study we use new planktic foraminiferal based sea-surface temperature (SST) estimates spanning the past 1 million years from a latitudinal transect of four deep ocean drilling sites. We conclude that: 1. the effect of the New Zealand landmass was to deflect the water masses south around the bathymetric impediments; 2. the effect of a shallow submerged ridge on the down-current side (Chatham Rise), was to dynamically trap the STF along its crest, in stark contrast to the usual glacial–interglacial (G–I) meridional migration that occurs in the open ocean; 3. the effect of more deeply submerged, downstream plateaux (Campbell, Bounty) was to dynamically trap the SAF along its steep southeastern margin; 4. the effects of saddles across the submarine plateaux was to facilitate the development of jets of subtropical and subantarctic surface water through the fronts, forming localized downstream gyres or eddies during different phases in the G–I climate cycles; 5. the deep Pukaki Saddle across the Campbell-Bounty Plateaux guided a branch of the SAF to flow northwards during each glacial, to form a strong gyre of circumpolar surface water in the Bounty Trough, especially during the mid-Pleistocene Climate Transition (MIS 22-16) when exceptionally high SST gradients existed across the STF; 6. the shallower Mernoo Saddle, at the western end of the Chatham Rise, provided a conduit for subtropical water to jet southwards across the STF in the warmest interglacial peaks (MIS 11, 5.5) and for subantarctic water to flow northwards during glacials; 7. although subtropical or subantarctic drivers can prevail at a particular phase of a G–I cycles, it appears that the Antarctic Circumpolar Current is the main influence on the regional hydrography. Thus complex submarine topography can affect distinct differences in the climate records over short distances with implications for using such records in interpreting global or regional trends. Conversely, the local topography can amplify the paleoclimate record in different ways in different places, thus enhancing its value for the study of more minor paleoceanographic influences that elsewhere are more difficult to detect. Such sites include DSDP 594, which like some other Southern Ocean sites, has the typical late Pleistocene asymmetrical saw-tooth G–I climate pattern transformed to a gap-tooth pattern of quasi-symmetrical interglacial spikes that interrupt extended periods of minimum glacial temperatures. [Copyright &y& Elsevier]

A detailed oxygen isotope time-scale based on planktonic foraminifera Globigerinoides sacculifer at site MD012380 in the Banda Sea was established for the past 820 kyrs by correlating the record to the astronomically tuned benthic oxygen isotope chronology of MD972143. Ages for marine isotope stratigraphic (MIS) events from 2.0 back to 21.1 were designated for this western tropical Pacific record. Spectral analysis of the δ18O time-series reveals distinct periodicities of 100, 41, and 23 kyrs, indicating strong orbital forcing, yet the power of each band varies through time. The time-series of three other paleo-proxies, namely, coarse fraction (CF), lightness of sediments and δ 13C of Globigerinoides sacculifer, were subjected to cross-spectral analyses against the oxygen isotope record. The Mid-Brunhes (MIS 13 - 10, 535 - 333 ka) divides the record into two time domains characterized by different spectral behaviors. Before the Mid-Brunhes, the analyzed proxies show relatively stronger powers at the 41-kyr band, and the coherence among various proxies is relatively high. After the Mid-Brunhes, 100-kyr periodicity becomes to dominate the δ 18O and coarse fraction records while coherence among the various proxies becomes weaker. The spectral behaviors of the various paleo-proxies appear to vary through the late Quaternary and are fundamentally changed by the Mid-Brunhes event, suggesting the existence of an ever changing, internally complicated system of the Banda Sea under the influence of orbital forcing during the last 820 kyrs. [ABSTRACT FROM AUTHOR]

Marine sediment core MD012394 from the Vietnam coastal upwelling area in the western South China Sea was investigated in order to reconstruct the last Quaternary monsoon upwelling based on planktic foraminifer fauna assemblages and fauna-based sea surface temperature (SST) estimates. The age model of core MD012394 was constructed using oxygen isotope stratigraphy of the planktic foraminifer G. sacculifer, with 10 accelerator mass spectrometry (AMS) 14C dating of planktic foraminifers from the sediment samples. Our studies on the relative and absolute abundances of planktic foraminifer assemblages reveal eight dominant species in core MD012394: N. dutertrei + N. pachyderma (right coiling), G. ruber, G. glutinata, G. sacculifer, P. obliquiloculata, G. menardii + G. tumida, G. calida, and G. inflata. In a Q-mode factor analysis of the fauna abundance data, the fauna factors show variations that do not parallel the glacial/interglacial changes throughout the last 135 kyr. The relative abundance patterns of G. inflata and N. dutertrei (including N. pachyderma-R) are interpreted as hydrographic proxies for East Asian summer and winter monsoon, respectively, in the current study. We calculated the fluctuations in the SST using the Revised Analog Method (RAM) in MD012394 and found that the abundance changes of the summer monsoon upwelling indicator G. inflata were similar and nearly synchronous. This suggests that the summer monsoon-driven upwelling signal was strong near the local summer insolation maximum, which induced low SSTs, particular around ~11, 33, 59, and 83 kya. Our studies support the view that the strengths of both summer insolation and the East Asian summer monsoon have determined the relative abundance of planktic foraminifers and the SSTs in the western SCS during the last 135 kyr. [ABSTRACT FROM AUTHOR]

A multiproxy study of palaeoceanographic and climatic changes in northernmost Baffin Bay shows that major environmental changes have occurred since the deglaciation of the area at about 12 500 cal. yr BP. The interpretation is based on sedimentology, benthic and planktonic foraminifera and their isotopic composition, as well as diatom assemblages in the sedimentary records at two core sites, one located in the deeper central part of northernmost Baffin Bay and one in a separate trough closer to the Greenland coast. A revised chronology for the two records is established on the basis of 15 previously published AMS 14C age determinations. A basal diamicton is overlain by laminated, fossil-free sediments. Our data from the early part of the fossiliferous record (12 300–11 300 cal. yr BP), which is also initially laminated, indicate extensive seasonal sea-ice cover and brine release. There is indication of a cooling event between 11 300 and 10 900 cal. yr BP, and maximum Atlantic Water influence occurred between 10 900 and 8200 cal. yr BP (no sediment recovery between 8200 and 7300 cal. yr BP). A gradual, but fluctuating, increase in sea-ice cover is seen after 7300 cal. yr BP. Sea-ice diatoms were particularly abundant in the central part of northernmost Baffin Bay, presumably due to the inflow of Polar waters from the Arctic Ocean, and less sea ice occurred at the near-coastal site, which was under continuous influence of the West Greenland Current. Our data from the deep, central part show a fluctuating degree of upwelling after c. 7300 cal. yr BP, culminating between 4000 and 3050 cal. yr BP. There was a gradual increase in the influence of cold bottom waters from the Arctic Ocean after about 3050 cal. yr BP, when agglutinated foraminifera became abundant. A superimposed short-term change in the sea-surface proxies is correlated with the Little Ice Age cooling. [ABSTRACT FROM AUTHOR]

Abstract  Contourite deposits in the central sector of the middle slope of the Gulf of Cadiz have been studied using a comprehensive acoustic, seismic and core database. Buried, mounded, elongated and separated drifts developed under the influence of the lower core of the Mediterranean Outflow Water are preserved in the sedimentary record. These are characterised by depositional features in an area where strong tectonic and erosive processes are now dominant. The general stacking pattern of the depositional system is mainly influenced by climatic changes through the Quaternary, whereas changes in the depositional style observed in two, buried, mounded drifts, the Guadalquivir and Huelva Drifts, are evidence of a tectonic control. In the western Guadalquivir Drift, the onset of the sheeted drift construction (aggrading QII unit) above a mounded drift (prograding QI unit) resulted from a new Lower Mediterranean Core Water hydrodynamic regime. This change is correlated with a tectonic event coeval with the Mid Pleistocene Revolution (MPR) discontinuity that produced new irregularities of the seafloor during the Mid- to Late-Pleistocene. Changes in the Huelva Drift from a mounded to a sheeted drift geometry during the Late-Pleistocene, and from a prograding drift (QI and most part of QII) to an aggrading one (upper seismic unit of QII), highlight a new change in oceanographic conditions. This depositional and then oceanographic change is associated with a tectonic event, coeval with the Marine Isotope Stage (MIS) 6 discontinuity, in which a redistribution of the diapiric ridges led to the development of new local gateways, three principal branches of the Mediterranean Lower Core Water, and associated contourite channels. As a result, these buried contourite drifts hold a key palaeoceanographic record of the evolution of Mediterranean Lower Core Water, influenced by both neotectonic activity and climatic changes during the Quaternary. This study is an example of how contourite deposits and erosive elements in the marine environment can provide evidence for the reconstruction of palaeoceanographic and recent tectonic changes. [ABSTRACT FROM AUTHOR]

The geological history of the Mediterranean Sea, its hydrography and connection with the Atlantic Ocean have been well documented. Despite a wealth of historical and oceanographic data, the Atlantic–Mediterranean transition remains controversial at the biological level as there are discordant results regarding the biogeographical separation between the Atlantic and Mediterranean biota. The opening of the Strait of Gibraltar at the end of the Messinian Salinity Crisis (some 5.33 million years ago), removed the land barrier that impeded the marine biota allowing it to disperse freely into the Mediterranean Sea. However, present day genetic patterns suggest a limitation to gene flow for some marine species, preventing population admixture. In the last few years, a large number of studies have challenged the hypothesis of the Strait of Gibraltar representing a phylogeographical break. A review of more than 70 papers reveals no obvious relationship between either dispersal ability or life history, and observed patterns of partial or complete genetic isolation between Atlantic and Mediterranean populations. We re-analysed a selection of this large body of data (20 studies in total) in order to provide a homogeneous and coherent view on the generality of the phylogeographical patterns and the presence of a phylogeographical barrier. This offered the opportunity to summarize the state of the art on this matter and reach some general conclusions on the evolutionary history across the Atlantic–Mediterranean range. Geographically, some species in the transition zone showed step changes of allele frequencies associated with the Almeria-Oran Front rather than with the Strait of Gibraltar itself. A major part of the data describe evolutionary events well within the time frame of the Quaternary age as very few taxa pre-date closure of the Tethys Sea. Results point to a combined signature of vicariance, palaeoclimate fluctuation and life-history traits on the Atlantic–Mediterranean phylogeographical patterns. Principal component analysis failed to show any particular association between biological traits and genetic variables. It would argue that organismal determinism may play a far less significant role than marine biogeographers have generally believed. [ABSTRACT FROM AUTHOR]

Abstract: Benthic foraminifera and carbon isotopes from closely spaced samples taken from three deep-sea cores were analysed to reconstruct the palaeoceanographic evolution of the eastern Indian Ocean for the last 30 kyrs, with an extension back to 60 kyrs based on one core. Benthic foraminifera were studied by means of Q-mode Factor Analysis. The benthic foraminifera accumulation rate (BFAR) and the accumulation rates (AR) of Bulimina aculeata, Epistominella exigua and Uvigerina proboscidea were calculated for determining episodes of increased organic matter supply to the sea floor. The δ18O and δ13C records of Cibicidoides wuellerstorfi were measured from all 3 cores to gather information about past intermediate- and deep-water circulation and changes in sea-surface palaeoproductivity. The co-variance of the organic matter supply and dissolved-oxygen levels affected the distribution of benthic foraminifera. Below a depth of 1800 m, reduced deep-water circulation was recognised by a low δ13C of C. wuellerstorfi and increased carbon-flux rate by a high BFAR and B. aculeata, E. exigua and U. proboscidea AR, as well as by a B. aculeata faunal dominance. A more oligotrophic environment was characterised by a low BFAR and B. aculeata, E. exigua and U. proboscidea AR. Active deep-water circulation was postulated with high δ13C values for C. wuellerstorfi and by a faunal dominance by C. wuellerstorfi. At intermediate depths (∼1000 m) and south of 20°S, the presence of strong bottom currents and the lateral advection of small amounts of organic matter, favoured the suspension feeder C. wuellerstorfi. Under extremely high dissolved-oxygen levels, determined by the increased influence of the Antarctic Intermediate Water (seen through high δ13C of C. wuellerstorfi) and a reduced supply of organic matter, Nummoloculina irregularis and Globocassidulina subglobosa dominated the benthic foraminifera assemblage. The reduction of oxygen levels, a more stratified water column and the Leeuwin Current flow, along its present pattern, favoured the species U. proboscidea and Bolivina robusta. Based on these observations, the following palaeoceanographic evolution of the eastern Indian Ocean is proposed: [•] For 60–35 kyr BP, conditions of higher productivity (compared to the Present) at the sea surface were suggested for the Banda Sea. [•] For 35–15 kyr BP, high productivity still characterised the Banda Sea. Strong and oxygenated bottom currents were present offshore Western Australia. For the Last Glacial Maximum, a reduction of deep-water circulation characterised the eastern Indian Ocean, while more active circulation was recorded at intermediate depths. Productivity also increased offshore the north coast of Western Australia [•] For 15–5 kyr BP, a reduction in productivity levels over the Banda Sea is related to increased atmospheric precipitation, which led to the formation of a low-salinity water cap at the sea surface. Off the north coast of Western Australia, productivity levels remained similar to those recorded for the LGM, probably due to the nutrients injected into the sea by rivers. Off the northwest coast of Western Australia, a deepened nutricline prevented any increase of organic matter supply to the sea floor. [•] For 5 kyr BP–Present, in the Banda Sea, productivity levels are similar to the Present. Off the Western Australian coast, an increased influence of the oxygen-depleted Indonesian Intermediate Water and the Leeuwin Current engendered a more stratified water column, characterised by lower dissolved-oxygen levels. [Copyright &y& Elsevier]

Abstract: Stratigraphic variations of coarse fraction, and frequency and thickness of turbidites in three cores collected along the Toyama Deep-Sea Channel (TDSC) in the central Japan Sea show consistent temporal trends with changes in terrestrial climatic records. These temporal changes in turbidite deposition may reflect climatic forcing in the sediment source areas for the last 70 ka. Comparison of temporal changes in turbidite deposition with paleoclimatic and paleoceanographic records in the central Japanese mainland and the Japan Sea revealed the following modes of climatic linkages; (1) During the stadials and interstadials of the last glacial period (70–22 ka) when the Tsushima Warm Current (TWC) periodically flowed into the Japan Sea, the Japanese mainland climate was cold and periodically wet, resulting in occasional glacial advances in adjacent mountains. Turbidite flux increased in the TDSC system during the major glacial advances because of the increased production of coarse debris by glacial processes and high transport potential due to high precipitation. (2) During the last glacial maximum (22–18 ka) when the Japan Sea was capped by cold, low-salinity surface water, the terrestrial climate was cold and dry due to low evaporation from the Japan Sea. As a result of low precipitation, less coarse debris was transported into deep basins, and so during this period, the turbidite flux along the TDSC was reduced. (3) During the last deglaciation (18–8 ka), precipitation in central Japan increased due to intensified summer monsoons. This resulted in destabilization of mountain slopes and increased transport of detritus to the lowlands and also to the TDSC system. (4) After the TWC flowed into the Japan Sea, the land climate became warm, wet, and stable. Enhanced vegetation and re-stabilized mountain slopes have reduced sediment input to the TDSC system since 8 ka. [Copyright &y& Elsevier]

Abstract: The East Asian winter monsoon is characterized by cold, dry air blowing from the Siberian high to the surrounding lows. This cold wind cools the surface water along the Russian coast of the Japan Sea. Modern oceanographic observations indicate that sea-ice formation along this coast during an extremely cold winter is an important process for deep-water formation. Thus, formation of both seasonal sea ice and deep-water masses in the Japan Sea are closely related to the East Asian winter monsoon. Two sediment cores were analyzed to reconstruct the history of sea-ice expansion and deep-water formation. Seasonal sea-ice history was reconstructed from the occurrence of ice-rafted debris (IRD) in a core from the northeastern Japan Sea, whereas the deep-water ventilation history was estimated on the basis of records of a deep-dwelling radiolarian species, Cycladophora davisiana, in a core from the southwestern Japan Sea. In the records of sea-ice expansion and deep-water ventilation for the last 160 ky, clear fluctuations on a millennial timescale were observed during marine oxygen isotope stages 3–5. Some of the peaks in sea-ice formation and C. davisiana abundance occurred contemporaneously, indicating strong surface cooling along the Russian coast by a strong winter monsoon. Decoupling of the two records might have occurred because of surface-water stratification caused by the freshening of surface water in relation to high precipitation in summer. Synchronicity of high IRD peaks with North Atlantic Heinrich events suggests that high-latitude climate changes related to the Bond cycle also occurred in the Asian monsoon region. On shorter timescales, IRD occurrence was not clearly related to Dansgaard–Oeschger cycles, which are revealed in the alternating dark and light layers in the late Quaternary Japan Sea sediments. Therefore, during the studied period, strong East Asian winter monsoons did not have a simple see-saw-like relationship with strong summer monsoons. [Copyright &y& Elsevier]

Abstract: Six piston cores (95PC-1, MB97PC-19, TY99-PC18, 95PC-3, 95PC-4 and 96EBP-4) from the East Sea (Japan Sea) were examined to assess the fluctuations in carbonate and biogenic silica sedimentation. Data from four of these cores (95PC-1, MB97PC-19, TY99-PC18 and 96EBP-4), collected from depths above the present carbonate compensation depth (CCD), clearly show that carbonate content increased during glacial periods and decreased during interglacial periods, whereas biogenic silica content shows the opposite pattern. The two cores collected below the CCD also show glacial/interglacial variations in carbonate and biogenic opal contents with patterns similar to the cores collected above the CCD. This study provides strong evidence for cyclic variations of biogenic components corresponding to interglacial–glacial cycles, even though variations in carbonate and opal contents seem to be affected by dissolution and dilution. The inverse correlation between carbonate and biogenic silica contents suggests that two mutually exclusive oceanic modes affected the biogenic sedimentation. These modes may have resulted from sea level changes that led to water column stratification during glacial low stands and breakdown of water column stratification, and consequent active vertical mixing during interglacial high stands. [Copyright &y& Elsevier]

Abstract: Paleoceanographic conditions in the Japan Sea changed drastically during the Late Quaternary in association with orbital and suborbital cycles and glacio-eustatic sea level changes. However, few studies have examined long-term sediment records older than 160 ka because of the lack of long and continuous cores and the difficulty in constructing high-resolution age models. In this study, we first constructed an orbital-scale stratigraphy of the sediments covering the last 640 kyr by comparing the SPECMAP ∂ 18O curve and the ∂ 18O curve of planktonic foraminifera (∂ 18Opf) in the Japan Sea together with the combination zones of dominant planktonic foraminifera species. Then, we reconstructed temporal variations in biogenic silica (BioSil) and biogenic carbonate (BioCarb) contents calculated from high-resolution major element analysis data determined by an XRF microscanner. In order to evaluate the deep-water oxygenation conditions, we also defined excess S as the difference between the content of S in the sediments and that for normal marine sediments calculated from the organic carbon content (Corg) estimated from lightness (L ⁎) by assuming a total sulfur content (Stotal)/Corg ratio of 0.36, and examined its variability. BioSil shows orbital-scale variation and is generally low except during interglacial maxima when global sea level was high enough to allow a strong influx of the Tsushima Warm Current. BioCarb shows orbital- and suborbital-scale variations and tends to be higher in dark layers deposited during glacial stages, whereas the relationship is reversed during interglacial stages. The low BioCarb in dark layers deposited during interglacial stages is probably due to dissolution of biogenic carbonate caused by the increase in surface productivity as a result of the strong influx of nutrient rich East China Sea Coastal Water and consequent increase in surface productivity and decomposition rate of organic matter in the intermediate water. Excess S tends to be higher in thicker dark layers deposited during glacial maxima when the sea level dropped below −90 m compared to adjacent light layers, suggesting development of euxinic deep-water conditions during these periods. The results demonstrated the presence of orbital- and suborbital-scale variations in BioSil and BioCarb and their association with dark and light layers in the Japan Sea that reflect variations in the nature and strength of inflow through the Tsushima Strait controlled by both climatic and sea level changes, whereas higher excess S reflects the development of euxinic deep-water condition during glacial maxima in association with glacio-eustatic sea level drops below −90 m during the last 640 kyr. [Copyright &y& Elsevier]

Abstract: The Quaternary hemipelagic sediments of the Japan Sea are characterized by centimeter-to decimeter-scale alternations of heavily bioturbated, organic-poor light layers and finely laminated, organic-rich dark layers. These dark and light layers, which can be correlated throughout the deeper part of the basin, are considered to reflect changes in bottom-water oxygenation. However, depositional mechanisms responsible for individual dark layers and causes of oxygen depletion are not fully understood. Two possible settings for deposition of organic-rich dark layers are recognized. One is a stratified ocean (like the Black Sea) where limited vertical advection results in euxinic conditions in the deeper parts of the basin. The other is an upwelling region (like the Arabian Sea) where the oxygen minimum zone is intensified by enhanced nutrient upwelling and surface productivity. In this study, fabrics of hemipelagic sediments deposited in the Japan Sea during the last 160 ka were studied in three cores collected from different latitudes and water depths. Fabrics were classified into 4 classes based on corresponding bottom-water oxygenation level. Five dark layer types were defined based on the distribution patterns of sediment fabric classes within each dark layer. Comparison of dark layer types at shallower and deeper sites in a chronologic framework provided evidence for five different modes of deep-water circulation. These circulation modes, which reflect relative intensities of upwelling and density stratification, appear to be related to global sea-level changes as well as climate impact on the nature of water influx through the Tsushima Strait. [Copyright &y& Elsevier]

Abstract: In order to reconstruct past sea surface temperature (SST) and salinity (SSS) in the East Sea (Japan Sea), this study investigated the oxygen isotopic composition of the planktonic foraminifer Globigerina bulloides, and the degree of unsaturation of alkenones in bulk sediments of core TY99PC18 recovered from the southeastern part of the Ulleung Basin, East Sea. Between 11 and 15 cal kyr BP, the surface waters were 2–4 °C cooler than today. The surface salinity was 12‰ lower during 14–15 cal kyr BP than today, then increased after 14 cal kyr BP, but remained lower during 11–14 cal kyr BP than present values. Between 14 and 15 cal kyr BP, the northern East China Sea surface waters were likely to be greatly diluted by fresh water discharge from land, and coastal waters would have flowed into the East Sea through the Korea Strait. During 11–14 cal kyr BP, the southern input waters most likely changed from fresh water-influenced coastal water to open ocean water. The increased salinity probably enhanced active deep water convection at that time. During 7–11 cal kyr BP, the surface waters were warmer (∼1 °C) and more saline (1–3‰) than today, indicating that the warm and saline Kuroshio Current became stronger, and that one of its branches flowed into the East Sea during this time interval. The cold (∼2 °C) and less saline waters (∼1‰) at 3–6 cal kyr BP may indicate a suppression of the Kuroshio Current. The SST and SSS values are close to the present values at about 3 cal kyr BP, suggesting that the physiological conditions of the East Sea approached that of the present at this time. [Copyright &y& Elsevier]

The late Quaternary calcareous nannofossil assemblages from Ocean Drilling Program Holes 807A and 846B, located in the western and eastern equatorial Pacific Ocean, respectively, were analyzed to clarify changes in surface-water conditions during the last 500 000 years. The uppermost Quaternary sediments in both holes contain abundant nannofossils, and their assemblages are characterized by high species diversity. The absolute abundances of coccoliths (specimens/g) and relative numbers of small reticulofenestrids decreased drastically in both holes between 0.3 and 0.2 Ma, whereas the relative abundance of warm-water species and Florisphaera profunda increased suddenly at this time. These data indicate that upwelling around the western and eastern equatorial Pacific regions weakened after 0.2 Ma, which was caused by a decrease in trade-wind strength. [ABSTRACT FROM AUTHOR]

Coral reefs are tropic to subtropic, coastal ecosystems comprising very diverse organisms. Late Quaternary reef deposits are fossil archives of environmental, tectonic and eustatic variations that can be used to reconstruct the paleoclimatic and paleoceanographic history of the tropic surface oceans. Reefs located at the latitudinal limits of coral-reef ecosystems (i.e. those at coral-reef fronts) are particularly sensitive to environmental changes – especially those associated with glacial–interglacial changes in climate and sealevel. We propose a land and ocean scientific drilling campaign in the Ryukyu Islands (the Ryukyus) in the northwestern Pacific Ocean to investigate the dynamic response of the corals and coral-reef ecosystems in this region to Late Quaternary climate and sealevel change. Such a drilling campaign, which we call the COREF (coral-reef front) Project, will allow the following three major questions to be evaluated: (i) What are the nature, magnitude and driving mechanisms of coral-reef front migration in the Ryukyus? (ii) What is the ecosystem response of coral reefs in the Ryukyus to Quaternary climate changes? (iii) What is the role of coral reefs in the global carbon cycle? Subsidiary objectives include (i) the timing of coral-reef initiation in the Ryukyus and its causes; (ii) the position of the Kuroshio current during glacial periods and its effects on coral-reef formation; and (iii) early carbonate diagenetic responses as a function of compounded variations in climate, eustacy and depositional mineralogies (subtropic aragonitic to warm-temperate calcitic). The geographic, climatic and oceanographic settings of the Ryukyu Islands provide an ideal natural laboratory to address each of these research questions. [ABSTRACT FROM AUTHOR]

A new method for reconstructing depositional environments of larger foraminifera-bearing limestones is proposed. First, depth and spatial distributions of empty tests of 10 foraminiferal taxa in a 1–2 mm size fraction were examined using 32 surface sediment samples collected from depths shallower than 200 m, located to the west of Miyako Island, Ryukyu Islands, northwest Pacific. Distributional ranges of empty tests in the 1–2 mm size fraction appear to be more limited than those including other size fractions in previous reports, partly because larger empty tests of each taxon are less easily transported than smaller ones. Multivariate analyses (Q-mode cluster analysis and non-metric multidimensional scaling ordination) based on binary (presence/absence) data of the 10 taxa delineate four sample groups, each of which corresponds to different depositional environments: nearshore zone/bay inlet; back-reef to fore-reef; outer shelf to shelf slope; and shelf slope distant from coral reefs. Next, these modern data were applied to reconstruct the depositional environment of a rock section distributed in the Shiratorizaki area (Irabu Island, Ryukyu Islands), which consists of larger foraminiferal limestone of the Pleistocene Ryukyu Group. Multivariate analyses were performed on the fossil plus the modern foraminiferal data to explore the possible relationship of the fossil associations with variations in modern associations, demonstrating that the fossil foraminiferal associations resemble the modern outer shelf associations. The modern analog technique was also applied to estimate paleobathymetry using fossil foraminiferal data. The results indicate that the section studied was deposited in outer shelf environments at depths between 53.5 and 98.6 m. These paleoenvironmental interpretations are consistent with previous studies based on sedimentary facies and the computer-based expert system. The modern dataset and methods used in our work would be particularly useful for paleoenvironmental reconstructions of Quaternary reef and shelf carbonates along active margins of the northwest Pacific. [ABSTRACT FROM AUTHOR]

Sedimentological and micropaleontological characteristics of core sediments from the outer shelf of the Korea Strait, which connects the northern East China Sea and the East Sea (Sea of Japan), were investigated to elucidate the paleoceanographic environment, especially the timing of the Kuroshio inflow, since the last glacial maximum. The core sediments, containing continuous records of the last 15,000 years, are characterized by a relatively high mud content (more than 50%, on average) and well-developed tide-influenced sedimentary structures. Their mineralogy suggests that the material originated from the paleo-Nakdong River system, which extended across the shelf of the Korea Strait during low sea-level periods. Planktonic foraminifers reveal a series of well-defined changes in paleoceanographic conditions during the late Pleistocene–Holocene. Down-core variations in the abundance of four foraminiferal assemblages, i.e., cold, coastal, tropical–subtropical, and Kuroshio water groups comprising characteristic planktonic species, suggest the occurrence of a distinct paleoenvironmental change in the surface water at 7,000 years b.p., i.e., from 15,000 to 7,000 years b.p., the area was influenced by coastal waters whereas since ca. 7,000 years b.p., it has been under the influence of open-sea water related to the Kuroshio Current flow, associated with both higher temperature and higher salinity. In particular, Pulleniatina obliquiloculata increased markedly in abundance at this time, documenting the inflow of the Kuroshio into the study area. These data indicate that the coastal water stage terminated at ca. 7,000 years b.p. when the warm Kuroshio and its major branch, the Tsushima Current, began to flow into the East Sea, as is the case today. The intrusion of the Tsushima Current through the Korea Strait after ca. 7,000 years b.p. resulted in abrupt changes in sedimentation rates and a dramatic increase in abundance of the Kuroshio indicator species, P. obliquiloculata. [ABSTRACT FROM AUTHOR]

High resolution records of atmospheric CO2 concentration during the Holocene are obtained from the Dome Concordia and Dronning Maud Land (Antarctica) ice cores. These records confirm that the CO2 concentration varied between 260 and 280 ppmv in the Holocene as measured in the Taylor Dome ice core. However, there are differences in the CO2 records most likely caused by mismatches in timescales. Matching the Taylor Dome timescale to the Dome C timescale by synchronization of CO2 indicates that the accumulation rate at Taylor Dome increased through the Holocene by a factor two and bears little resemblance to the stable isotope record used as a proxy for temperature. This result shows that different locations experienced substantially different accumulation changes, and casts doubt on the often-used assumption that accumulation rate scales with the saturation vapor pressure as a function of temperature, at least for coastal locations. [Copyright &y& Elsevier]

Focuses on the process of calcium carbonate pump during Quaternary glacial cycles in the South China Sea. Analysis on the carbonate contents, carbonate MAR, benthic foraminiferal and planktoni foraminiferal fragmentation with high resolution; Indication of the highest carbonate accumulation rate; Suggestion of stronger carbonate dissolution that made the calcium carbonate pump transporting atmospheric carbon dioxide.

The Wilkes Land continental rise is characterised by mounds and channels with approximately a north–south elongation, perpendicular to the margin. Proximal mound relief is up to 1000 m, decreasing to about 300 m in the central part. During the geophysical and geological survey conducted on in February–March 2000 by the joint Italian and Australian WEGA Project, onboard R/V Tangaroa, 11 piston cores were collected along two transects crossing the channel-mound system. All cores were logged for physical (magnetic susceptibility and density) and acoustic properties (P-wave velocity). Split cores were X-rayed and samples were analysed for clay mineral assemblages, chemical and micropaleontological (diatoms, foraminifera and nannofossils) content.Glacial and interglacial intervals have been recognised in the sediment cores. The interglacial facies consists of massive mud, distinguished by: (a) bioturbated massive mud occasionally with fine-grained ice-rafted debris (IRD), and (b) structureless massive mud with abundant fine to coarse-grained IRD, containing well-preserved open-ocean diatoms. The glacial facies is represented by laminated mud with planar and/or cross laminations, with occasional isolated dropstones, and rare, poorly preserved, sea-ice diatoms. The sharp boundary, characterizing the limit between massive to laminated facies, is interpreted to indicate a fast glacial onset. In contrast, the smooth passage presents from laminated to massive sediments, indicates a gradual glacial waning.Recent down-slope gravity flows have been identified in a turbidite, a normally graded coarse-grained sand, recovered in the thalweg of Jussie Canyon, and probably also in the massive debris facies from the steep side of Mound A. The massive debris is characterised by structureless and unsorted gravel and pebbles within a muddy matrix. Clay mineral assemblages and grain lithologies indicate a hinterland Wilkes Basin and continental shelf provenance for the terrigenous fraction. [Copyright &y& Elsevier]

Examines the Radiolarian fossil groups since 1.2 MaBP in ODP leg 184 site 1143, the southern South China Sea (SCS). Finding of significant variation in radiolarian abundance; Increase with low extent between 0.9-0.65 Ma, which corresponds to the Mid-Pleistocene Transition stage; Indication the average abundance rose higher in each stage,while showing periodic fluctuations; The increase after 0.65 MaBP is thought to be from the enhanced upwelling in this region; Influence of an intensified monsoon circulation after the "Mid-Pleistocene Transition"; Finding from spectral analyses that a long oscillation of ∼0.2 Ma cycle, found in the records of radiolarian abundance and complex diversity, corresponds to other paleoceanographic indexes; Suggestion that this could be a special cycle characteristic of paleoecological environment evolution in this area; Indication of an obvious boundary in about 0.47 MaBP that shows an abrupt variation of the community structure and radiolarian abundance level.

Seven oceanic island groups (Chatham, Bounty, Snares, Antipodes, Auckland, Campbell and Macquarie) lie to the south and east of the southern New Zealand mainland between the Subtropical Convergence and the Antarctic Convergence. They are highly oceanic, experiencing moist, cool, cloudy and windy climates. Deep peat soils cover most of the islands, except for steep slopes and exposed high altitude sites. The three large island groups (Chatham, Auckland and Campbell) support forest and tall scrub in the lowlands, in the latter two grading with altitude through shrubland and grassland to upland tundra. Macrophyllous forbs create luxuriant herbfields in nutrient-rich coastal sites and also, as stunted forms, dominate upland tundra associations. The southernmost island, Macquarie has no woody species, and is covered with tussock grassland, herbfield and tundra. Vegetation cover is highly sensitive to soil saturation and exposure to the strong westerly winds of this region. Extensive oligotrophic bogs occur where drainage is poor and exposure high, and forest and tall scrub are abundant only in sheltered, well-drained lowland sites. Glacial cirque levels indicate mean annual temperatures fell by 5–6°C during the Last Glacial Maximum. A depression of 6–10°C in sea surface temperatures is suggested by deep-sea core analyses, but this seems incompatible with terrestrial evidence. Auckland and Campbell Islands were extensively glaciated, and grassland, herbfield and tundra landscapes prevailed. Glaciers retreated by 15,000 yr BP, and landscapes had stabilised and peat soils begun forming by 12,000 yr BP. By the beginning of the Holocene, oligotrophic bog, grassland and shrubland were dominant. Scrub and low forest spread slowly during the early Holocene in the Chatham, Auckland and Campbell Islands, inhibited by cloudy, moist climates, low insolation and wet soils. Maximum extent of forest and scrub occurred between 6000 and 2000 yr BP, most probably linked with a drying of the soils and increasing summer insolation. Upland sites and those exposed to westerly gales on Auckland and Campbell Islands remained in grassland, herbfield and bog throughout the Holocene. Wind-blown sand and stones in cliff edge peat profiles on Auckland and Campbell Island from 8000 yr BP suggest strengthening westerly winds. [Copyright &y& Elsevier]

Provides information on paleoceanography at the Okinawa Through during the Quaternary period. Methodology; Results; Details on variable climate shifts.

Presents information on a study which described the seismic coverage, the problems of interpretation and the integration of the seismic models with the borehole data along the north Norfolk coast in the United Kingdom. Sedimentological and stratigraphic background; Geophysical considerations; Results of refraction profiles.

Detailed sedimentological and stratigraphic analyses were carried out on seven Kullenberg cores collected across the Brazilian continental margin during the French cruises Byblos and Apsara III, in order in highlight the factors controlling the sediment flux distribution in the Southern Brazil Basin during the late Quaternary. On the continental slope and upper continental rise above 3000 m depth, sediment fluxes are important and highly variable (4.2-14.2 g cm[SUP-2] 10[SUP-3]yr). The sediments show a pelagic or turbiditic character, depending on the width of the shelf and proximity of canyons, The material is characterized by high kaolinite contents, and originates from the coastal rivers draining the South American continent north of Rio de Janeiro. On the middle continental rise between 3000 and 4000 m depth, sediment fluxes are the lowest observed in the area [0.9 g cm[SUP-2] 10[SUP-3] yr), because terrigenous input is trapped at shallower depths on the Sãn Paulo Plateau. Pelagic settling is the dominant process, In the deep domains, below, 4000 m depth, contouritic accumulations are developed on the path of the northwards moving Antarctic bottom water (AABW) currents. The deposits consist of fine-grained silty-clayey muds with very low carbonate contents. The sediment fluxes (l.45 g cm[SUP-2] 10[SUP-3] yr) are higher than on the middle continental rise, as a consequence of fine-grained terrigenous supply derived from higher latitudes (Argentine Basin and Southern Ocean), and transported in the basin through the Vema Channel by the AABW currents. This material is characterized by high smectite and chlorite contents. These data reveal large sediment flux variations which are linked to distinct depth-related domains. Such a distribution is the consequence of the presence of two available sources of terrigenous sediments: (1) the Brazilian continental areas with a downslope material transport and a sediment distribution controlled by the morphology of... [ABSTRACT FROM AUTHOR]

The article discusses various reports published within the issue including one by P. S. Yu et al on foraminiferal assemblage from the Vietnam coastal upwelling area and another by L. J. Shiau et al who imply that there was a major phytoplankton community structure change during glacial-interglacial cycles.