On the fine structure of oxygen distribution in surface water layers in the area between Iceland and Faroe Islands

During the international "Overflow-Expedition'' 1973 on R.V. "Meteor" oxygen concentrations in surface layers were measured in order to determine the oxygen gradients within the first two meters and to add some informations to the mechanisms of oxygen exchange at the air-sea interface. These investigations may be interesting also with regard to longterm- observations of the oxygen distribution in the Atlantic, especially the problem of the A.O.U. (apparent oxygen utilization) determination. To measure oxygen gradients a special sampler was built which is able to take water samples each 20 cm of the first 2 meters. These data were supplemented by further samples down to 150 m, taken by conventional water samplers, from which samples were also taken to measure N2/O2-relations. By comparing these relations with theoretical relations in air-saturated water the influence of biological production and consumption on the oxygen contents in water could be estimated. A simple glass apparatus was built to extract gas from the water samples, and hereafter the N2/O2-relations were determined by mass spectrometry. Most distributions of the oxygen anomaly show a negative oxygen balance which varies largely, probably due to strong mixing processes in the Iceland-Faroe ridge area. The distribution of surface oxygen saturation values are of two different types. The values of the stations 260, 262 and 270 stem from mixed water and show homogeneous supersaturations, as can be found instantly when whitecaps appear. The values of 9 other stations are from water, sampled during calm periods which has been mixed and supersaturated before. They show a decreasing oxygen saturation towards the sea surface and often undersaturation in the upper decimeters up to 98 % and even 91 %. So at the air-sea interface even less initial oxygen saturation than 100 % can be found after supersaturation during heavy weather periods.

Maps and acoustic profiles of free gas distribution, Western Baltic Sea and Kattgat-Skagerrak area

A shallow gas depth-contour map covering the Skagerrak-western Baltic Sea region has been constructed using a relatively dense grid of existing shallow seismic lines. The digital map is stored as an ESRI shape file in order to facilitate comparison with other data from the region. Free gas usually occurs in mud and sandy mud but is observed only when sediment thickness exceeds a certain threshold value, depending on the water depth of the area in question. Gassy sediments exist at all water depths from approx. 20 m in the coastal waters of the Kattegat to 360 m in the Skagerrak. In spite of the large difference in water depths, the depth of free gas below seabed varies only little within the region, indicating a relatively fast movement of methane in the gas phase towards the seabed compared to the rate of diffusion of dissolved methane. Seeps of old microbial methane occur in the northern Kattegat where a relatively thin cover of sandy sediments exists over shallow, glacially deformed Pleistocene marine sediments. Previous estimates of total methane escape from the area may be correct but the extrapolation of local methane seepage rate data to much larger areas on the continental shelf is probably not justified. Preliminary data on porewater chemistry were compared with the free gas depth contours in the Aarhus Bay area, which occasionally suffers from oxygen deficiency, in order to examine if acoustic gas mapping may be used for monitoring the condition of the bay.

Distribution of benthic abyssal gastropods in the Iberian Deep-Sea Basin (Table 2)

During the cruises 3 and 15 of R.V. "Meteor", representatives of 7 families of benthic abyssal gastropods were collected. The prevalent group was the Turridae; the Naticidae are represented by 2 species, the remaining families by a single species each. A survey of the frequency and distribution of the species within the study area is given. A systematic part deals with the individual species in detail, including notes on taxonomy, material and distribution. Concerning the composition of the abyssal gastropod fauna of the present material, Neogastropoda are 4 times as many as Archaeogastropoda and 6 times as many as Mesogastropoda and Opisthobranchia. 89 % of all specimens are Neogastropoda. Usually deep-sea organisms have a non-pelagic development, but many of the Iberian deep-sea Turrids have a planktotrophic protoconch, that means a long pelagic larval period. Among the 19 species, 2 are cosmopolitan, 9 show a transatlantic distribution and 8 are confined to East-Atlantic basins.

Distribution of living benthic foraminifera in sediment cores of cruise M77 Leg 1 and 2, 63-2000 µm fraction

Recent benthic foraminifera and their distribution in surface sediments were studied on a transect through the Peruvian oxygen minimum zone (OMZ) between 10 and 12°S. The OMZ with its steep gradients of oxygen concentrations allows to determine the oxygen-dependent changes of species compositions in a relatively small area. Our results from sediments of thirteen multicorer stations from 79 to 823 m water depth demonstrate that calcareous species, especially bolivinids dominate the assemblages throughout the OMZ. The depth distribution of several species matches distinct ranges of bottom water oxygen levels. The distribution pattern inferred a proxy which allows to estimate dissolved oxygen concentrations for reconstructing oxygen levels in the geological past.

Characteristics of the Vernagtferner mass balance for the period from 1964 to 2014

The main characteristics of the Vernagtferner mass balance are sumarized in the table below. The mass balance years from 1964/65 to 2003/2004 are listed. The table includes the total area of the glacier (basis for the calculations), the equilibrium line altitude (ELA), percentage of the accumulation area in relation to the total area (AAR) and the specific net mass balance in mm w.e. (water equivalent) per year. It becomes clear that, after a rather minor growth period in the mid 1970's, the glacier continually lost mass since the beginning of the 1980's. Besides that, a clear increase of mass balance years with extreme mass losses could be observed in the last decade. The "glacier-friendly" summer with a well-balanced mass balance in 1999 could only interrupt the series of years with extreme mass losses, but this means no change in the trend. The minor mass loss in 1999 was caused by a winter snow cover above average, which prevented the glacier from becoming snow free over large areas and thus resulted in a lower ice melt. Although real summer conditions in 2000 were mainly restricted to August and produced a snow free area only slightly larger than in 1999, there have been further ice losses. This trend of negative mass balance continued also in the years 2001 and 2002. Nevertheless, the losses are moderate because a smaller part of the glacier became ice free until autumn (appr. 50 %). The summer 2003 caused a loss of ice in a dimension never seen since the beginning of the scientific investigations. This resulted from a combination of different factors: after only a moderate winter snowcover the glacier became snow free very early. For the first time the ablation area spanned over the entire glacier (blue fields in the mass balance tables!). Only one short snowfall event interrupted the ablation period, which lasted twice as long as in the years of large losses in the 1990's. The extreme mass loss in 2003 will also influence the mass balance in the following year 2004. The graphical representation of the elevation distribution of the specific mass balance together with the absolute mass balance can be found individually for each year by choosing one of the mass balance values from the table. These diagrams also include the area-height-distribution of the glacier and the ablation area. A tabular version of the numeric values in dependence of the elevation, provided separately for the accumulation area, the ablation area and the total glacier, can be found in colums "Persistent Identifier". The tables include the results for three different parts of the glacier and for the total glacier.

(Table 2) Geochemistry and petrograhy of DSDP Leg 82 Holes and MAPCO cruise of Jean Charcot in the Mid-Atlantic Ridge area

The compositions of abyssal glasses obtained on Leg 82 of the awGlomar Challenger and the MAPCO cruise of Jean Charcot have been investigated. Two main compositional groups of Atlantic glasses (A1 and A2) that are separated in space and time were identified. The distribution of these groups in the studied area allowed mapping of the transition zone from A1 to A2 between 30-35°N MAR. We infer that the compositional groups of abyssal glasses of the Atlantic and other oceans reflect the depth of separation of primary melts from the oceanic mantle. Specifically, the primary melt of Group A1 separates from the mantle at a depth of 30-60 km (spinel-peridotite facies) and those for Group A2 from a depth of 15-30 km (plagioclase-peridotite facies). Modifications of dynamic models of the ocean lithosphere are discussed.

Abundance of thecosomatous pteropods in the Arabian Sea and Persian Gulf (Table 2)

This paper deals with the presence and distribution of Thecosomatous Pteropods in the Indian Ocean. 122 plankton-samples, taken by R.V. "Meteor" during the International Indian Ocean Expedition (IIOE) in 1964-65 were investigated. They contain a total number of about 45000 Thecosomata, belonging to 22 species and 5 families. Some species (e.g. Creseis acicula and Limacina inflata) are common in the entire area, others (e.g. Creseis chierchiae and Desmopterus gardinieri) show a quite distinct distribution. From several species only one single specimen was captured, others are completely lacking in the collection though they have been reported frequently from the same area by other expeditions. This may be due to seasonal variations and to the fact that no bathial tows were taken. In spite of these restrictions the extensive material from a relatively small area offers the possibility to compare specific and nonspecific features in related species and to question their taxonomic value.

(Table 3) Basal melting rates under the Amery Ice Shelf, East Antarctica

The basal melting and freezing rates under the Amery Ice Shelf, East Antarctica, are evaluated, and their spatial distributions mapped. Ice velocity, surface elevation and accumulation rate datasets are employed in the analysis, along with a column-averaged ice density model. Our analysis shows that the total area of basal melting is 34 700 km**2, with a total annual melt of 62.5 ± 9.3 Gt and an average melting rate of 1.8 ± 0.3 m/a. Basal freezing mainly occurs in the northwestern part of the ice shelf, over a total area of 26100 km**2 and with a maximum freezing rate of 2.4 ± 0.4 m/a. The total marine ice that accretes to the ice-shelf base is estimated to be 16.2 ± 2.4 Gt/a. Using a redefined grounding line and geometry of the Amery Ice Shelf, we estimate the net melt over the ice-shelf base is about 46.4 ± 6.9 Gt/a, which is higher than previous modeling and oceanographic estimates. Net basal melting accounts for about half of the total ice-shelf mass loss, with the rest being from iceberg discharge. Our basal melting and freezing distribution map provides a scientific basis for quantitative analysis of ice-ocean interaction at the ice-shelf-ocean interface.

Ostracoda fauna of surface sediments from the Persian Gulf

During the "Meteor"-Expedition to the Persian Gulf in March-May 1965, approximately 300 samples were collected. Most of them have been already studied by various authors in sedimentological as well as micropaleontological respects. 49 samples were selected for ostracode studies. These samples are arranged to form a long-axis section ("Laengsprofil"), and 4 shorter cross-profiles, perpendicular to the long-axis profile in the Persian Gulf and Gulf of Oman. 52 species of ostracodes in this area were specifically determined; 39 of them are described under open nomenclature. 13 species are already known from surrounding sea areas: 2 species from the Red Sea; 2 species from the east coast of Africa; 1 species from the Mediterranean Sea; and others from the Indian and Pacific Oceans. 12 species show close relationships to species from the Indopacific Ocean. The ostracode species found in the area can be grouped after the method of BRAUN-BLANQUT into 2 bioassociations. Association 1 with the following 4 characteristic species : Cytherella cf. pulchra, Loxoconcha sp. A, Neomonoceratina sp. A, Alocopocythere reticulata. Association 2 with 1 characteristic species: Ruggieria (Ruggieria) sp. B. The association 1 is widespread in the entire studied area of the Persian Gulf, where it is considered to characterize the shallow water region down to 200 m. The association 2 is restricted to the deeper water below 200 m of the inner part of the Oman Gulf. Only a few species known from the shallow water association of the Persian Gulf are present. Within the two ostracode associations mentioned above 4 zones from the total studied area could be related to the water depth. The zones A-D are characterized more or less readily by the relative abundance of certain species: Zone A : 7-30 m depth, on substrates of poorly coarse-grained clayey marl; Zone B: 30-94 m depth, on substrates of richly coarse-grained calcareous marl; Zone C: 94-1961208 m depth, on substrates of richly coarse-grained calcareous marl; Zone D: 196/208-500 m depth, on substrates of calcareous clay, poor in benthos. The regional and bathymetric distribution of the ostracode fauna in the area studied was compared in relation to 10 environmental factors: water depth, temperature, salinity, water density, O2-concentration, phosphate-silica contents, pH-values, stratification of the water body, water currents and type of sediments. The major environmental factors which appear to control the ostracode distribution are water depth (as a complex factor), O2-concentration and the type of sediment. At 3 stations (GIK01058, GIK01074 and GIK01204) species of the shallow water association were found together with a few bathyal species. These stations are situated at the outer Biaban shelf, in an area where the bottom water of the Persian Gulf flows down the slope towards the Oman Gulf. Several samples of the Zone B in the major part of the Persian Gulf show also a high species diversity containing a high percentage of subfossil ostracode carapaces. It is probable that the recent biocoenosis has been mixed with a late quarternary thanatocoenosis.

(Supplemet S1) Silicon oxide and Potassium + Sodium oxide from the PACManus hydrothermal area

This study presents a systematic analysis and interpretation of autonomous underwater vehicle-based microbathymetry combined with remotely operated vehicle (ROV) video recordings, rock analyses and temperaturemeasurements within the PACManus hydrothermal area located on Pual Ridge in the Bismarck Sea of eastern Manus Basin. The data obtained during research cruise Magellan-06 and So-216 provides a framework for understanding the relationship between the volcanism, tectonismand hydrothermal activity. PACManus is a submarine felsic vocanically-hosted hydrothermal area that hosts multiple vent fields locatedwithin several hundredmeters of one another but with different fluid chemistries, vent temperatures and morphologies. The total area of hydrothermal activity is estimated to be 20,279m**2. Themicrobathymetrymaps combinedwith the ROV video observations allow for precise high-resolution mapping estimates of the areal extents of hydrothermal activity.We find the distribution of hydrothermal fields in the PACManus area is primarily controlled by volcanic features that include lava domes, thick andmassive blocky lava flows, breccias and feeder dykes. Spatial variation in the permeability of local volcanic facies appears to control the distribution of venting within a field.We define a three-stage chronological sequence for the volcanic evolution of the PACManus based on lava flow morphology, sediment cover and lava SiO2 concentration. In Stage-1, sparsely to moderately porphyritic dacite lavas (68-69.8 wt.% SiO2) erupted to form domes or cryptodomes. In Stage-2, aphyric lava with slightly lower SiO2 concentrations (67.2-67.9 wt.% SiO2) formed jumbled and pillowed lava flows. In the most recent phase Stage-3, massive blocky lavaswith 69 to 72.5wt.% SiO2were erupted throughmultiple vents constructing a volcanic ridge identified as the PACManus neovolcanic zone. The transition between these stages may be gradual and related to progressive heating of a silicic magma following a recharge event of hot, mantle-derived melts.

(Table 1) Grain size composition of recent sediments from the eastern Barents Sea shelf

Based on materials on geomorphology, hydrology, lithology, and sedimentation dynamics obtained during cruises of the P.P. Shirshov Institute of Oceanology in the Barents Sea, the author prepared a number of charts on content of the main particle size facies in shelf surface sediments, as well as a chart of lithologic types of sediments in the Barents Sea. Factors of sedimentation control and basic features of distribution of sedimentary material over its bottom area are taken into consideration.

Nd and Sr isotope record of ODP Sites 121-756 and 122-762 sediments

We have analyzed the Nd isotopic composition of both ancient seawater and detrital material from long sequences of carbonated oozes of the South Indian Ocean which are ODP Site 756 (Ninety East Ridge (-30°S), 1518 m water depth) and ODP Site 762 (Northwest Australian margin, 1360 m water depth). The measurements indicate that the epsilon-Nd changes in Indian seawater over the last 35 Ma result from changes in the oceanic circulation, large volcanic and continental weathering Nd inputs. This highlights the diverse nature of those controls and their interconnections in a small area of the ocean. These new records combined with those previously obtained at the equatorial ODP Sites 757 and 707 in the Indian Ocean (Gourlan et al., 2008, doi:10.1016/j.epsl.2007.11.054) established that the distribution of intermediate seawater epsilon-Nd was uniform over most of the Indian Ocean from 35 Ma to 10 Ma within a geographical area extending from 40°S to the equator and from -60°E to 120°E. However, the epsilon-Nd value of Indian Ocean seawater which kept an almost constant value (at about -7 to -8) from 35 to 15 Ma rose by 3 epsilon-Nd units from 15 to 10 Ma. This sharp increase has been caused by a radiogenic Nd enrichment of the water mass originating from the Pacific flowing through the Indonesian Passage. Using a two end-members model we calculated that the Nd transported to the Indian Ocean through the Indonesian Pathway was 1.7 times larger at 10 Ma than at 15 Ma. The Nd isotopic composition of ancient seawater and that of the sediment detrital component appear to be strongly correlated for some specific events. A first evidence occurs between 20 and 15 Ma with two positive spikes recorded in both epsilon-Nd signals that are clearly induced by a volcanic crisis of, most likely, the St. Paul hot-spot. A second evidence is the very large epsilon-Nd decrease recorded at ODP Sites 756 and 762 during the past 10 Ma which has never been previously observed. The synchronism between the epsilon-Nd decrease in seawater from 10 to 5 Ma and evidences of desertification in the western part of the nearly Australian continent suggests enhanced weathering inputs in this ocean from this continent as a result of climatic changes.

Sediment budget and geomorphic process units of the Swedish Kärkevagge, link to ArcInfo E00 files

Geomorphic process units have been derived in order to allow quantification via GIS techniques at a catchment scale. Mass movement rates based on existing field measurements are employed in the budget calculations. In the Kärkevagge catchment, Northern Sweden, 80% of the area can be identified either as a source area for sediments or as a zone where sediments are deposited. The overall budget for the slopes beneath the rockwalls in the Kärkevagge is approximately 680 t/a whilst about 150 t a-1 are transported into the fluvial system.

Chemical composition of Fe-Mn nodule from Station PL70-9

During June-August 1970 geologic investigations were carried out to the west of the Cape Verde Islands. One result of these investigations was a discovery of a new region of distribution of iron-manganese nodules. Data on chemical analysis of the nodules and their morphometric characteristics are presented in this paper. The report is illustrated by bottom-relief profiles, underwater photographs, and tables.