(Table 2) Trace metal concentrations in ODP Hole 169-1033B

We measured the concentrations of redox-sensitive trace metals (Mn, V, Mo, U, Cd and Re) in sediments from ODP Leg 169S Hole 1033B in Saanich Inlet, British Columbia, to determine changes in redox conditions associated with the onset of laminated sediments at ~12.5 kyr. The most striking result is a large peak in authigenic Re along with detrital levels of Mo at the glacial terrigenous clay-diatomaceous sediment transition. In contrast, the underlying glacial terrigenous clay, which extends throughout the bottom section of the core, is chemically similar to detrital concentrations, either Cowichan River particulates or average shale values. These data suggest a period of oxic bottom waters but reducing pore-waters. This could be due to the dramatic transformation of Saanich Inlet during the late deglaciation from an open bay to an inlet, which restricted circulation and slowed bottom water oxygen renewal. A peak and gradual increase in authigenic Mn in younger sediments subsequent to the Re peak suggests that increasingly oxic conditions followed the authigenic enrichment in Re. These conditions could be connected to the Younger Dryas cooling period, which was coincident with an increase in well oxygenated upwelled waters on the west coast of North America that form the bottom waters of Saanich Inlet. Metal concentrations in a gray clay bed (~11 kyr) are similar to their concentrations in the glacial terrigenous clay, implying that they have a common source. Authigenic enrichments of Re with little authigenic Mo and Cd suggest that before the deposition of this bed, bottom waters were oxic and pore-water oxygen was consumed in the top centimeter or less. Laminations above the clay layer suggest anoxic conditions, which are also indicated by higher authigenic Mo and Cd and slightly lower Re/Mo ratios in these sediments. The basin remained mostly anoxic after the gray clay was emplaced, as seen by continuous authigenic enrichment of the redox-sensitive trace metals. These results are consistent with increased stratification of the water column, brought about by an influx of fresh water to the basin by a large flood.

3D models created from ROV videos and their corresponding subtransect dimensions

Underwater video transects have become a common tool for quantitative analysis of the seafloor. However a major difficulty remains in the accurate determination of the area surveyed as underwater navigation can be unreliable and image scaling does not always compensate for distortions due to perspective and topography. Depending on the camera set-up and available instruments, different methods of surface measurement are applied, which make it difficult to compare data obtained by different vehicles. 3-D modelling of the seafloor based on 2-D video data and a reference scale can be used to compute subtransect dimensions. Focussing on the length of the subtransect, the data obtained from 3-D models created with the software PhotoModeler Scanner are compared with those determined from underwater acoustic positioning (ultra short baseline, USBL) and bottom tracking (Doppler velocity log, DVL). 3-D model building and scaling was successfully conducted on all three tested set-ups and the distortion of the reference scales due to substrate roughness was identified as the main source of imprecision. Acoustic positioning was generally inaccurate and bottom tracking unreliable on rough terrain. Subtransect lengths assessed with PhotoModeler were on average 20% longer than those derived from acoustic positioning due to the higher spatial resolution and the inclusion of slope. On a high relief wall bottom tracking and 3-D modelling yielded similar results. At present, 3-D modelling is the most powerful, albeit the most time-consuming, method for accurate determination of video subtransect dimensions.

Sea surface temperature (Mg/Ca) from ODP Hole 161-977A

Mg/Ca, Sr/Ca, and stable isotope measurements have been performed on tests from the planktonic foraminifers Globigerinoides ruber (white), Globigerina bulloides, and Neogloboquadrina pachyderma (right coiling) in samples from Ocean Drilling Program site 977A in the Alboran Sea (Western Mediterranean). The evolution of different water masses between 250 and 150 ka is described. Warm substages were characterized by strong seasonality and thermal stratification of the water column. By contrast, less pronounced seasonality and basin stratification seem to prevail during cold substages. Several periods of stratification due to the low salinity of the upper water mass occurred during the formation of organic-rich layers and also during a possible Heinrich-like event at 220 ka. The three foraminifer species studied show a common and large shell Sr/Ca variability in short timescales, suggesting changes in the global ocean Sr/Ca ratio as one of the main causes of variations in shell composition.

Astronomical time scale for Paleocene and early Eocene sediments

The astronomical-tuned time scale is rapidly extended into the Paleogene but, due to the existence of an Eocene gap, different tuning options had to be presented for the Paleocene. These options differ both in number and tuning of ~405-kyr eccentricity related cycles and are only partially consistent with recalculated 40Ar/39Ar constraints for the Cretaceous/Paleogene (K/Pg) and Paleocene/Eocene (P/E) boundaries. In this paper, we evaluate the cyclostratigraphic interpretation of records from ODP Leg 198 and 208 sites, and the Zumaia section to solve the problem of the different tuning options. We found that the interval between the K/Pg boundary and the early Late Paleocene biotic event (ELPE) comprises 17 instead of 16 * ~405-kyr eccentricity related cycles as previously proposed, while the entire Paleocene contains 25 * ~405-kyr cycles. Starting from 40Ar/39Ar age constraints for the K/Pg boundary, a new tuning to 405-kyr eccentricity is presented for the Paleocene and earliest Eocene, which results in ages of ~66.0 and ~ 56.0 Ma for the K/Pg and P/E boundaries, respectively. This tuning introduces considerable differences in age for a number of nannofossil events at ODP Sites 1209 and 1262 in the interval between 61 and 63 Ma, but eliminates large and abrupt changes in the seafloor spreading rate. The tuning seems further consistent with recalculated 40Ar/39Ar ages for ash layer -17 of early Eocene age. However, despite this apparent consistency with existing radio-isotopic constraints, an alternative 405-kyr younger or, less likely, older tuning cannot be excluded at this stage.

Latest Cretaceous to Late Paleocene radiolarian biostratigraphy from the New Zealand region

The scarcity of records of Early Paleocene radiolarians has meant that while radiolarian biostratigraphy is firmly established as an important tool for correlation, there has been a long-standing gap between established zonations for the Cretaceous and from latest Paleocene to Recent. It has also led to considerable speculation over the level of faunal change across the Cretaceous/Tertiary (K/T) boundary. Consequently, the discovery of rich and diverse radiolarian assemblages in well-delineated K/T boundary sections within siliceous limestones of the Amuri Limestone Group in eastern Marlborough, New Zealand, is of great significance for biostratigraphy and K/T boundary research. This initial report is restricted to introducing a new latest Cretaceous to mid Late Paleocene zonation based on the radiolarian succession at four of these sections and a re-examination of faunas from coeval sediments at DSDP Site 208 (Lord Howe Rise). Three new Paleocene species are described: Amphisphaera aotea, Amphisphaera kina and Stichomitra wero. Six new interval zones are defined by the first appearances of the nominate species. In ascending order these are: Lithomelissa? hoplites Foreman (Zone RK9, Cretaceous), Amphisphaera aotea n. sp. (Zone RP1, Paleocene), Amphisphaera kina n. sp. (RP2), Stichomitra granulata Petrushevskaya (RP3), Buryellaforemanae petrushevskaya (RP4) and Buryella tetradica (RP5). Good age control from foraminifera and calcareous nannofossils permits close correlation with established microfossil zonations. Where age control is less reliable, radiolarian events are used to substantially improve correlation between the sections. No evidence is found for mass extinction of radiolarians at the end of the Cretaceous. However, the K/T boundary does mark a change from nassellarian to spumellarian dominance, due to a sudden influx of actinommids, which effectively reduces the relative abundance of many Cretaceous survivors. An accompanying influx of diatoms in the basal Paleocene of Marlborough, together with evidence for an increase of total radiolarian abundance, suggests siliceous plankton productivity increased across the K/T boundary. Possible causes for this apparently localised phenomenon are briefly discussed.

(Table 1) Helium concentration in sediments

Two decades ago, Merrihue (1964) reported 3He/4He ratios of >10**-4 in ferromagnetic separates from a Pacific deep ocean red clay and concluded that the high ratio is due to extraterrestrial debris amounting to ~1% of the sediment. A decade later Krylov et al. (1973) compiled 3He/4He isotopic data on ocean sediments measured in the Soviet Union and observed that the 3He/4He ratio is generally higher in pelagic sediments where the sedimentation rate is lower. They suggested that the high 3He/4He ratio was attributable to extraterrestrial materials which were concentrated in slowly accumulating ocean floor. However, these important discoveries were almost completely neglected until we re-examined the problem. We have measured 39 sediments from 12 different sites, 10 sites from the western to central Pacific and two sites from the Atlantic Ocean. We find 3He/4He ratios >5 * 10**-5 for six sites, well above the values generally observed in common terrestrial materials. The very high 3He/4He ratio in the sediments is probably due to input of extraterrestrial materials. Input of stratospheric dust of <1 p.p.m., which corresponds to a fallout rate of ~2,000 tons per year, can explain the observation.

Weighted mean depth of zooplankton measured during various cruises to the Baltic Sea

The Baltic Sea is the largest brackish water area of the world. On the basis of the data from 16 cruises, we show the seasonal and vertical distribution patterns of the appendicularians Fritillaria borealis, Oikopleura dioica and the cyclopoid copepod Oithona similis, in the highly stratified Bornholm Basin. These species live at least temporarily below the permanent halocline and use different life strategies to cope with the brackish environment. The cold-water species F. borealis is abundant in the upper layers of the water column before the thermocline develops. With the formation of the thermocline abundance decreases and the specimens outlast higher temperatures below the halocline. Distribution and strategy suggest that F. borealis might be a glacial relict species in the Baltic Sea. Although Oikopleura dioica is only abundant during summer, O. similis is present all year round. Both species have in common that their vertical distribution is restricted to the waters below the halocline, most likely due to their requirements of higher salinities. We argue that the observed strategies are determined by ecophysiological constraints and life history traits. These species share an omnivorous feeding behaviour and the capability to utilise a spectra of small particles as food. As phytoplankton concentration is negligible below the halocline, we suggest that these species feed on organic material and heterotrophic organisms that accumulate in the density gradient of the halocline. Therefore, the deep haline waters in the Baltic Sea represent a habitat providing shelter from predation and food supply for adapted species that allows them to gather sufficient resources and to maintain populations.

Descriptions of 104 gravity and piston sediment cores from POLARSTERN expedition ARK-VIII/3 to the Arctic Ocean

Sediment descriptions and lithostratigraphy (chapter 6.4) NANSEN BASIN The upperrnost 20-50 cm of sedirnents in the Nansen Basin norrnally cornprise soft dark brown, brown-grayish and brown clay. Except for the toprnost clay, the four piston cores retrieved, contained quite different lithologies: a rnuddy diarnicton with outsized clasts (PS2157-6), sandy-silt beds alternating with clay beds (PS2159-6), and silty clay beds of brownish and grayish colours (PS2161-3). Core PS2208-3 was retrieved frorn a plateau on a searnount. The plateau was serni-encircled by hills. The upper 250 cm of this core cornprise brown and olive brown clays. Below these are several sandlayers and a 74 cm thick unit of a sandy mud with rnud-clasts up to 20 cm in diameter. GAKKEL RIDGE The uppermost 20-50 cm of sediments on the Gakkel Ridge comprise soft dark brown, brown, grayish brown clay. In most of the cores there are two horizons of brown clay separated by olive brown clay. The upper horizon is darker. The older stratigraphy is rather varied. Core PS2165-1 contains several thin gray sandlsilt layers, probably distal turbidites. The sarne is found in Core PS2167-1. This core also has a thick (approx. 2 rn) coarse grained turbidite containing large rnud clasts and basaltic rock fragrnents. The color of the turbiditic layers is dark gray. There are several horizons of hernipelagic sandylsilty clays with quite a variety in colours; black, gray, olive, brown, yellowish brown and reddish. The colour variation rnay be due to hydrotherrnal activity or provenance or a shift in redox potential. Cores PS2168-2 and PS2169-1 have typical sequences of very dark gray sandy mud with sharp lower boundaries grading upwards into olive brown clay. Below the lower boundary is often a thin (1-2 cm) gray clay layer. AMUNDSEN BASIN The giant box cores (GKG) provided in most cases excellently preserved sedirnent surfaces which consisted in the entire Amundsen Basin of dark brown to dark grayish brown silty clay with few dropstones and common calcareous microfossils (foraminifers and calcareous nannofossils). The brown and grayish brown color of the sediment surface is a result of the oxidizing conditions at the seafloor due to the rapid renewal of the bottom water rnasses. Planktic forarninifers and calcareous nannofossils are relatively frequent and well preserved despite the rernote location of the basin and its water depths of >4000 rn. Srnear slide descriptions have shown that the surface sedirnents consist dorninantly of clays to silty rnuds with clay rninerals and quartz as the rnost important constituents. The coarse fractions contained besides planktic and benthic forarninifers and coarse clastic rnaterials, rare bivalves, dropstones and mud clasts. The Station PS2190 at the North Pole is a particular good exarnple of the type of sedirnents deposited at the sea floor surface of the Arnundsen Basin, with hornogenous dark brown soft clay covering a sedirnent sequence of highly variable cornposition. Nurnerous giant box cores also provide insight into the detailed lithostratigraphy of the upperrnost sedirnent layers. Twelve box cores have been collected frorn the Arnundsen Basin. Below the youngest unit of 5-20 crn thick silty clays deposits of variable stratigraphies have been found, rnostly consisting of clays or silty clays. In a few instances turbidites have been observed. Benthic forarninifers have not been found in the surface sedirnents. Other fossils were extrernely rare. Bioturbation is weakly developed on all stations. Benthic anirnals seern to live only in and on the upperrnost 2 cm of the uppermost sediment layer. They cornprise amphipods (on all stations) and holothurians, bryozoans, polychaetes, and porifers at one station each. LOMONOSOV RIDGE Sediments from the Lomonosov Ridge show a variety of colors and textures. Following smear slide analyses they are composed mostly of clay minerals and quartz with mica and feldspars, especially in the siltier and sandier parts. Volcanic glass, microcrystalline carbonate, opaque minerals and green amphibole are occasional accessories. The sediments from the Lomonosov Ridge show a noticeable difference from sediments collected from the surrounding basins. Lomonosov Ridge sediments are richer in silt and sand than basin sediments. Occasional turbidites occur in ridge sediments but these must be of entirely local origin. The ridge sediments include frequent layers of "cottage cheese" texture made up of what appear to be small, angular mud clasts of a variety of colors.

(Table 1) Concentrations of polybrominated diphenyl ethers in liver and plasma samples of ringed seals (Phoca hispida)

The present study investigated the concentrations and patterns of PBDEs and hydroxylated (OH) PBDE analogues in two ringed seal populations: less contaminated Svalbard and more contaminated Baltic Sea. Mean concentration of hepatic sum-PBDE, which was dominated by BDE47, was six times higher in the ringed seals from the Baltic Sea compared to the seals from Svalbard. BDE47/sum-PBDE was higher in the seals from Svalbard compared to that for Baltic seals, while the trend was opposite for BDE153 and 154. The geographical difference in contaminant pattern of PBDEs in ringed seals could be explained by biotransformation via oxidative metabolism and/or by dietary differences. OH-PBDEs were detectable in the majority of plasma samples from both locations, and dominated by bioaccumulation of naturally occurring congeners. Low levels of 3-OH-BDE47 and 4'-OH-BDE49 in the Baltic ringed seals suggested minor oxidative biotransformation of BDE47. In the Baltic seals, BDE153/sum-PBDEs and BDE154/sum-PBDEs increased and BDE28/sum-PBDE decreased with increasing sum-POP concentration, which suggests BDE153 and 154 are more persistent than BDE28. Contrasting diets of the ringed seals in these two locations may influence the PBDE congener pattern due to selective long-range transport and direct effluent emissions to Svalbard and the Baltic, respectively.

Investigations on two sediment cores from the Arctic Ocean

During the "RV Polarstem"-Expedition ARK VIII/2 sediment samples were obtained at the continental slope of NW-Spitsbergen. Detailed sedimentological and geochemical analysis were carried out at two undisturbed box cores (PS2122-1GKG, PS2123-2GKG) as well as two gravity cores (PS2122-1SL, PS2123-2SL). The following parameters were deterrnined: Organic carbon, nitrogen and carbonate contents, hydrogen index, stable isotopes, ice rafted debris, grain-size distribution and biogenic opal. The main objective of this study was the reconstruction of paleoenvironmental changes off the northwest coast of Spitsbergen during the last glacial/interglacial-cycle, i.e., during the last about 128.000 years. The results of the investigations can be summarized as follows: - During isotope stage 1 (Holocene) and 5.5 (Eemian Interglacial), light stable isotopes (d180: 3.4-2 %o; d13C: 0.26-0.5 %o), increased bioturbation, high content of planktonic foraminifera and biogenic opal and low quantity of ice-rafted material, indicate seasonally ice-free conditions along the northwest coast due to the intfluence of the Westspitsbergen Current. - Additionally, the sediment characteristics of the middle of isotope stage 2 (Last Glacial Maximum) and at the end of stage 3 confirms an inflow of warmer Atlantic water. The highest production of planktonic and benthic foraminifera (N. pachyderma sin., Cassidulina teretis) (CaC03: 10 %) may reflect the expansion of the 'Whalers Bay'-Polynya as a result of the influence of the Westspitsbergen Current. Presumably, occasionally open-ice conditions provide sufficient precipitation to buildup the Svalbard/Barents Ice Sheet. - The time intervals for the glacier advances on Svalbard given by Mangerud et al. (1992), can be correlated with increased accumulation of ice-rafted material in the sediments at the northwest coast of Spitsbergen. Especially during isotope stage 4 and at the beginning of the Last Glacial Maximum (isotope stage 2), a drastically increased supply of coarse terrigenous material occurs. The high accumulation rate (0.18-0.21 g/cm**2/ka) of terrigenous organic carbon is indicated by high C/N ratios (until 16) and low hydrogen index (50 mg HC/gC). In constrast to deep sea sediments in the Fram-Strait (Hebbeln 1992), the glacier advance between 118.000 and 108.000 years B.P. ist documented in the continental slope sediments. - At the end of the Weichselian ice age, the deglaciation at the northwest coast starts with a typical melt-water signal in the stables isotope record (d18O: 3.5 %o; d13C: -0.16 %o) and high contents of gravel (6-13 %). The signal can be assigned to an event at the westcoast of Spitsbergen (core NP90-39), dated to 14.500 years B.P. (Andersen et al. 1993).