Global planktonic foraminifera seasonality

Shell fluxes of planktonic Foraminifera species vary intra-annually in a pattern that appears to follow the seasonal cycle. However, the variation in the timing and prominence of seasonal flux maxima in space and among species remains poorly constrained. Thus, although changing seasonality may result in a flux-weighted temperature offset of more than 5° C within a species, this effect is often ignored in the interpretation of Foraminifera-based paleoceanographic records. To address this issue we present an analysis of the intra-annual pattern of shell flux variability in 37 globally distributed time series. The existence of a seasonal component in flux variability was objectively characterised using periodic regression. This analysis yielded estimates of the number, timing and prominence of seasonal flux maxima. Over 80% of the flux series across all species showed a statistically significant periodic component, indicating that a considerable part of the intra-annual flux variability is predictable. Temperature appears to be a powerful predictor of flux seasonality, but its effect differs among species. Three different modes of seasonality are distinguishable. Tropical and subtropical species (Globigerinoides ruber (white and pink varieties), Neogloboquadrina dutertrei, Globigerinoides sacculifer, Orbulina universa, Globigerinella siphonifera, Pulleniatina obliquiloculata, Globorotalia menardii, Globoturborotalita rubescens, Globoturborotalita tenella and Globigerinoides conglobatus) appear to have a less predictable flux pattern, with random peak timing in warm waters. In colder waters, seasonality is more prevalent: peak fluxes occur shortly after summer temperature maxima and peak prominence increases. This tendency is stronger in species with a narrower temperature range, implying that warm-adapted species find it increasingly difficult to reproduce outside their optimum temperature range and that, with decreasing mean temperature, their flux is progressively more focussed in the warm season. The second group includes the temperate to cold-water species Globigerina bulloides, Globigerinita glutinata, Turborotalita quinqueloba, Neogloboquadrina incompta, Neogloboquadrina pachyderma, Globorotalia scitula, Globigerinella calida, Globigerina falconensis, Globorotalia theyeri and Globigerinita uvula. These species show a highly predictable seasonal pattern, with one to two peaks a year, which occur earlier in warmer waters. Peak prominence in this group is independent of temperature. The earlier-when-warmer pattern in this group is related to the timing of productivity maxima. Finally, the deep-dwelling Globorotalia truncatulinoides and Globorotalia inflata show a regular and pronounced peak in winter and spring. The remarkably low flux outside the main pulse may indicate a long reproductive cycle of these species. Overall, our analysis indicates that the seasonality of planktonic Foraminifera shell flux is predictable and reveals the existence of distinct modes of phenology among species. We evaluate the effect of changing seasonality on paleoceanographic reconstructions and find that, irrespective of the seasonality mode, the actual magnitude of environmental change will be underestimated. The observed constraints on flux seasonality can serve as the basis for predictive modelling of flux pattern. As long as the diversity of species seasonality is accounted for in such models, the results can be used to improve reconstructions of the magnitude of environmental change in paleoceanographic records.

Particle flux measurements from moorings and surface sediment studies of sediment cores in the SE Pacific Ocean

Flux of siliceous plankton and taxonomic composition of diatom and silicoflagellate assemblages were determined from sediment trap samples collected in coastal upwelling-influenced waters off northern Chile (30°S, CH site) under "normal" or non-El Niño (1993-94) and El Niño conditions (1997-98). In addition, concentration of biogenic opal and siliceous plankton, and diatom and silicoflagellate assemblages preserved in surface sediments are provided for a wide area between 27° and 43°S off Chile. Regardless of the year, winter upwelling determines the maximum production pattern of siliceous microorganisms, with diatoms numerically dominating the biogenic opal flux. During the El Niño year the export is markedly lower: on an annual basis, total mass flux diminished by 60%, and diatom and silicoflagellate export by 75%. Major components of the diatom flora maintain much of their regular seasonal cycle of flux maxima and minima during both sampling periods. Neritic resting spores (RS) of Chaetoceros dominate the diatom flux, mirroring the influence of coastal-upwelled waters at the CH trap site. Occurrence of pelagic diatoms species Fragilariopsis doliolus, members of the Rhizosoleniaceae, Azpeitia spp. and Nitzschia interruptestriata, secondary components of the assemblage, reflects the intermingling of warmer waters of the Subtropical Gyre. Dictyocha messanensis dominates the silicoflagellate association almost year-around, but Distephanus pulchra delivers ca. 60% of its annual production in less than three weeks during the winter peak. The siliceous thanatocoenosis is largely dominated by diatoms, whose assemblage shows significant qualitative and quantitative variations from north to south. Between 27° and 35°S, the dominance of RS Chaetoceros, Thalassionema nitzschioides var. nitzschioides and Skeletonema costatum reflects strong export production associated with occurrence of coastal upwelling. Both highest biogenic opal content and diatom concentration at 35° and 41°-43°S coincide with highest pigment concentrations along the Chilean coast. Predominance of the diatom species Thalassiosira pacifica and T. poro-irregulata, and higher relative contribution of the silicoflagellate Distephanus speculum at 41°-43°S suggest the influence of more nutrient-rich waters and low sea surface temperatures, probably associated with the Antarctic Circumpolar Water.

Isotopic composition of strontium in planktonic foraminiferas from sediments of the DSDP Holes 90-588 and 94-607

Measurements of 87Sr/86Sr on samples of planktonic foraminifers were used to reconstruct changes in the Sr isotopic composition of seawater for the past 8 Ma. The late Neogene was marked by a general, but not regular, increase in 87S/86Sr with two breaks in slope at 5.5 and 2.5 Ma. These times mark the beginning of two periods of steep increase in 87Sr/86Sr values, relative to preceding periods characterized by essentially constant values. During the last 2.5 Ma, 87Sr/86Sr values increased at an average rate of 0.000054/Ma. This steep increase suggests that the modem ocean is not in Sr isotopic equilibrium relative to its major input fluxes. A non-equilibrium model for the modern Sr budget suggests that the residence time of Sr is ~2.5 Ma, which is significantly less than previously accepted estimates of 4-5 Ma. Modelling results suggest that the increase in 87Sr/86Sr over the past 8 Ma could have resulted from a 25% increase in the riverine flux of Sr or an increase in the average 87Sr/86Sr of this flux by 0.0006. The dominant cause of increasing 87Sr/86Sr values of seawater during the late Neogene is believed to be increased rates of uplift and chemical weathering of mountainous regions. Calculations suggest that uplift and weathering of the Himalayan-Tibetan region alone can account for the majority of the observed 87Sr/86Sr increase since the early Late Miocene. Exhumation of Precambrian shield areas by continental ice-sheets may have contributed secondarily to accelerated mechanical and chemical weathering of old crustal silicates with high 87Sr/86Sr values. In fact, the upturn in 87Sr/86Sr at 2.5 Ma coincides with increased glacial activity in the Northern Hemisphere. A variety of geochemical (87Sr/86Sr, Ge/Si, d13C, CCD, etc.) and sedimentologic data (accumulation rates) from the marine sedimentary record are compatible with a progressive increase in the chemical weathering rate of continents and dissolved riverine fluxes during the late Cenozoic. We hypothesize that chemical weathering of the continents and dissolved riverine fluxes to the oceans reached a maximum during the late Pleistocene because of repeated glaciations, increased continental exposure by lowered sea level, and increased continental relief resulting from high rates of tectonism.

Glacier mass balances of Stubacher Sonnblickkees, Hohe Tauern Range, Eastern Alps, Austria, 1958/1959 to 2012/2013

Stubacher Sonnblickkees (SSK) is located in the Hohe Tauern Range (Eastern Alps) in the south of Salzburg Province (Austria) in the region of Oberpinzgau in the upper Stubach Valley. The glacier is situated at the main Alpine crest and faces east, starting at elevations close to 3050 m and in the 1980s terminated at 2500 m a.s.l. It had an area of 1.7 km² at that time, compared with 1 km² in 2013. The glacier type can be classified as a slope glacier, i.e. the relief is covered by a relatively thin ice sheet and there is no regular glacier tongue. The rough subglacial topography makes for a complex shape in the surface topography, with various concave and convex patterns. The main reason for selecting this glacier for mass balance observations (as early as 1963) was to verify on a complex glacier how the mass balance methods and the conclusions - derived during the more or less pioneer phase of glaciological investigations in the 1950s and 1960s - could be applied to the SSK glacier. The decision was influenced by the fact that close to the SSK there was the Rudolfshütte, a hostel of the Austrian Alpine Club (OeAV), newly constructed in the 1950s to replace the old hut dating from 1874. The new Alpenhotel Rudolfshütte, which was run by the Slupetzky family from 1958 to 1970, was the base station for the long-term observation; the cable car to Rudolfshütte, operated by the Austrian Federal Railways (ÖBB), was a logistic advantage. Another factor for choosing SSK as a glaciological research site was the availability of discharge records of the catchment area from the Austrian Federal Railways who had turned the nearby lake Weißsee ('White Lake') - a former natural lake - into a reservoir for their hydroelectric power plants. In terms of regional climatic differences between the Central Alps in Tyrol and those of the Hohe Tauern, the latter experienced significantly higher precipitation , so one could expect new insights in the different response of the two glaciers SSK and Hintereisferner (Ötztal Alps) - where a mass balance series went back to 1952. In 1966 another mass balance series with an additional focus on runoff recordings was initiated at Vernagtfener, near Hintereisferner, by the Commission of the Bavarian Academy of Sciences in Munich. The usual and necessary link to climate and climate change was given by a newly founded weather station (by Heinz and Werner Slupetzky) at the Rudolfshütte in 1961, which ran until 1967. Along with an extension and enlargement to the so-called Alpine Center Rudolfshütte of the OeAV, a climate observatory (suggested by Heinz Slupetzky) has been operating without interruption since 1980 under the responsibility of ZAMG and the Hydrological Service of Salzburg, providing long-term met observations. The weather station is supported by the Berghotel Rudolfshütte (in 2004 the OeAV sold the hotel to a private owner) with accommodation and facilities. Direct yearly mass balance measurements were started in 1963, first for 3 years as part of a thesis project. In 1965 the project was incorporated into the Austrian glacier measurement sites within the International Hydrological Decade (IHD) 1965 - 1974 and was afterwards extended via the International Hydrological Program (IHP) 1975 - 1981. During both periods the main financial support came from the Hydrological Survey of Austria. After 1981 funds were provided by the Hydrological Service of the Federal Government of Salzburg. The research was conducted from 1965 onwards by Heinz Slupetzky from the (former) Department of Geography of the University of Salzburg. These activities received better recognition when the High Alpine Research Station of the University of Salzburg was founded in 1982 and brought in additional funding from the University. With recent changes concerning Rudolfshütte, however, it became unfeasible to keep the research station going. Fortunately, at least the weather station at Rudolfshütte is still operating. In the pioneer years of the mass balance recordings at SSK, the main goal was to understand the influence of the complicated topography on the ablation and accumulation processes. With frequent strong southerly winds (foehn) on the one hand, and precipitation coming in with storms from the north to northwest, the snow drift is an important factor on the undulating glacier surface. This results in less snow cover in convex zones and in more or a maximum accumulation in concave or flat areas. As a consequence of the accentuated topography, certain characteristic ablation and accumulation patterns can be observed during the summer season every year, which have been regularly observed for many decades . The process of snow depletion (Ausaperung) runs through a series of stages (described by the AAR) every year. The sequence of stages until the end of the ablation season depends on the weather conditions in a balance year. One needs a strong negative mass balance year at the beginning of glacier measurements to find out the regularities; 1965, the second year of observation resulted in a very positive mass balance with very little ablation but heavy accumulation. To date it is the year with the absolute maximum positive balance in the entire mass balance series since 1959, probably since 1950. The highly complex ablation patterns required a high number of ablation stakes at the beginning of the research and it took several years to develop a clearer idea of the necessary density of measurement points to ensure high accuracy. A great number of snow pits and probing profiles (and additional measurements at crevasses) were necessary to map the accumulation area/patterns. Mapping the snow depletion, especially at the end of the ablation season, which coincides with the equilibrium line, is one of the main basic data for drawing contour lines of mass balance and to calculate the total mass balance (on a regular-shaped valley glacier there might be an equilibrium line following a contour line of elevation separating the accumulation area and the ablation area, but not at SSK). - An example: in 1969/70, 54 ablation stakes and 22 snow pits were used on the 1.77 km² glacier surface. In the course of the study the consistency of the accumulation and ablation patterns could be used to reduce the number of measurement points. - At the SSK the stratigraphic system, i.e. the natural balance year, is used instead the usual hydrological year. From 1964 to 1981, the yearly mass balance was calculated by direct measurements. Based on these records of 17 years, a regression analysis between the specific net mass balance and the ratio of ablation area to total area (AAR) has been used since then. The basic requirement was mapping the maximum snow depletion at the end of each balance year. There was the advantage of Heinz Slupetzky's detailed local and long-term experience, which ensured homogeneity of the series on individual influences of the mass balance calculations. Verifications took place as often as possible by means of independent geodetic methods, i.e. monoplotting , aerial and terrestrial photogrammetry, more recently also the application of PHOTOMODELLER and laser scans. The semi-direct mass balance determinations used at SSK were tentatively compared with data from periods of mass/volume change, resulting in promising first results on the reliability of the method. In recent years re-analyses of the mass balance series have been conducted by the World Glacier Monitoring Service and will be done at SSK too. - The methods developed at SSK also add to another objective, much discussed in the 1960s within the community, namely to achieve time- and labour-saving methods to ensure continuation of long-term mass balance series. The regression relations were used to extrapolate the mass balance series back to 1959, the maximum depletion could be reconstructed by means of photographs for those years. R. Günther (1982) calculated the mass balance series of SSK back to 1950 by analysing the correlation between meteorological data and the mass balance; he found a high statistical relation between measured and determined mass balance figures for SSK. In spite of the complex glacier topography, interesting empirical experiences were gained from the mass balance data sets, giving a better understanding of the characteristics of the glacier type, mass balance and mass exchange. It turned out that there are distinct relations between the specific net balance, net accumulation (defined as Bc/S) and net ablation (Ba/S) to the AAR, resulting in characteristic so-called 'turnover curves'. The diagram of SSK represents the type of a glacier without a glacier tongue. Between 1964 and 1966, a basic method was developed, starting from the idea that instead of measuring years to cover the range between extreme positive and extreme negative yearly balances one could record the AAR/snow depletion/Ausaperung during one or two summers. The new method was applied on Cathedral Massif Glacier, a cirque glacier with the same area as the Stubacher Sonnblickkees, in British Columbia, Canada. during the summers of 1977 and 1978. It returned exactly the expected relations, e.g. mass turnover curves, as found on SSK. The SSK was mapped several times on a scale of 1:5000 to 1:10000. Length variations have been measured since 1960 within the OeAV glacier length measurement programme. Between 1965 and 1981, there was a mass gain of 10 million cubic metres. With a time lag of 10 years, this resulted in an advance until the mid-1980s. Since 1982 there has been a distinct mass loss of 35 million cubic metres by 2013. In recent years, the glacier has disintegrated faster, forced by the formation of a periglacial lake at the glacier terminus and also by the outcrops of rocks (typical for the slope glacier type), which have accelerated the meltdown. The formation of this lake is well documented. The glacier has retreated by some 600 m since 1981. - Since August 2002, a runoff gauge installed by the Hydrographical Service of Salzburg has recorded the discharge of the main part of SSK at the outlet of the new Unterer Eisboden See. The annual reports - submitted from 1982 on as a contractual obligation to the Hydrological Service of Salzburg - document the ongoing processes on the one hand, and emphasize the mass balance of SSK and outline the climatological reasons, mainly based on the met-data of the observatory Rudolfshütte, on the other. There is an additional focus on estimating the annual water balance in the catchment area of the lake. There are certain preconditions for the water balance equation in the area. Runoff is recorded by the ÖBB power stations, the mass balance of the now approx. 20% glaciated area (mainly the Sonnblickkees) is measured andthe change of the snow and firn patches/the water content is estimated as well as possible. (Nowadays laserscanning and ground radar are available to measure the snow pack). There is a net of three precipitation gauges plus the recordings at Rudolfshütte. The evaporation is of minor importance. The long-term annual mean runoff depth in the catchment area is around 3.000 mm/year. The precipitation gauges have measured deficits between 10% and 35%, on average probably 25% to 30%. That means that the real precipitation in the catchment area Weißsee (at elevations between 2,250 and 3,000 m) is in an order of 3,200 to 3,400 mm a year. The mass balance record of SSK was the first one established in the Hohe Tauern region (and now since the Hohe Tauern National Park was founded in 1983 in Salzburg) and is one of the longest measurement series worldwide. Great efforts are under way to continue the series, to safeguard against interruption and to guarantee a long-term monitoring of the mass balance and volume change of SSK (until the glacier is completely gone, which seems to be realistic in the near future as a result of the ongoing global warming). Heinz Slupetzky, March 2014

Consolidation properties and hydraulic conductivities of sediments from ODP Leg 207 sites

The stress history, permeability, and compressibility of sediments from Demerara Rise recovered during Ocean Drilling Program Leg 207 were determined using one-dimensional incremental load consolidation and low-gradient flow pump permeability tests. Relationships among void ratio, effective stress, and hydraulic conductivity are presented for sampled lithologic units and used to reconstruct effective stress, permeability, and in situ void ratio profiles for a transect of three sites across Demerara Rise. Results confirm that a significant erosional event occurred on the northeastern flank of the rise during the late Miocene, resulting in the removal of ~220 m of upper Oligocene-Miocene deposits. Although Neogene and Paleogene sediments tend to be overconsolidated, Cretaceous sediments are normally consolidated to underconsolidated, suggesting the presence of overpressure. A pronounced drop in permeability occurs at the transition from the Cretaceous black shales into the overlying Maastrichtian-upper Paleocene chalks and clays. The development of a hydraulic seal at this boundary may be responsible for overpressure in the Cretaceous deposits, leading to the lower overconsolidation ratios of these sediments. Coupled with large regional variations in sediment thickness (overburden stresses), the higher permeability overpressured Cretaceous sediments represent a regional lateral fluid conduit on Demerara Rise, possibly venting methane-rich fluids where it outcrops on the margin's northeastern flank.

Maestrichtian through Neogene benthic foraminifers of Maud Rise

Upper abyssal to lower bathyal benthic foraminifers from ODP Sites 689 (present water depth 2080 m) and 690 (present water depth 2941 m) on Maud Rise (eastern Weddell Sea, Antarctica) are reliable indicators of Maestrichtian through Neogene changes in the deep-water characteristics at high southern latitudes. Benthic foraminiferal faunas were divided into eight assemblages, with periods of faunal change at the early/late Maestrichtian boundary (69 Ma), at the early/late Paleocene boundary (62 Ma), in the latest Paleocene (57.5 Ma), in the middle early Eocene to late early Eocene (55-52 Ma), in the middle middle Eocene (46 Ma), in the late Eocene (38.5 Ma), and in the middle-late Miocene (14.9-11.5 Ma). These periods of faunal change may have occurred worldwide at the same time, although specific first and last appearances of deep-sea benthic foraminifers are commonly diachronous. There were minor faunal changes at the Cretaceous/Tertiary boundary (less than 14?7o of the species had last appearances at Site 689, less than 9% at Site 690). The most abrupt benthic foraminiferal faunal event occurred in the latest Paleocene, when the diversity dropped by 50% (more than 35% of species had last appearances) over a period of less than 25,000 years; after the extinction the diversity remained low for about 350,000 years. The highest diversities of the post-Paleocene occurred during the middle Eocene; from that time on the diversity decreased steadily at both sites. Data on faunal composition (percentage of infaunal versus epifaunal species) suggest that the waters bathing Maud Rise were well ventilated during the Maestrichtian through early Paleocene as well as during the latest Eocene through Recent. The waters appeared to be less well ventilated during the late Paleocene as well as the late middle through early late Eocene, with the least degree of ventilation during the latest Paleocene through early Eocene. The globally recognized extinction of deep-sea benthic foraminifers in the latest Paleocene may have been caused by a change in formational processes of the deep to intermediate waters of the oceans: from formation of deep waters by sinking at high latitudes to formation of deep to intermediate water of the oceans by evaporation at low latitudes. Benthic foraminiferal data (supported by carbon and oxygen isotopic data) suggest that there was a short period of intense formation of warm, salty deep water at the end of the Paleocene (with a duration of about 0.35 m.y.), and that less intense, even shorter episodes might have occurred during the late Paleocene and early Eocene. The faunal record from the Maud Rise sites agrees with published faunal and isotopic records, suggesting cooling of deep to intermediate waters in the middle through late Eocene.

Flow rates, hydraulic conductivities and permeabilities of sediments from ODP Holes 190-1173A and 190-1174B

Understanding the role of fluids in active accretionary prisms requires quantitative knowledge of parameters such as permeability. We report here the results of permeability tests on four samples from Ocean Drilling Program Leg 190 at the Nankai Trough accretionary prism-two from Site 1173 and two from Site 1174. Volcanic ash is present in one of the samples; otherwise, the material is hemipelagic mud. A constant-rate-of-flow technique was used at various effective pressures and rates of flow. The permeability of the four samples ranges between 10**-15 and 10**-18 m**2, with the ash-bearing sample showing the highest values.

(Table 1) Physical properties of sediments at DSDP Holes 69-504 and 69-505

Values of physical properties measured in the upper sections of sediment cores recovered at Sites 504 and 505 exhibit a remarkable similarity. Below a depth of 145 m Site 504 sediments appear to have undergone changes which are reflected in physical property values. This alteration may have been due to high temperatures in the sediment. In most of Site 505, and in Site 504 above 145 m, seismic velocity averages 1.51 km/s, wet bulk density 1.32 g/cm**3, porosity 80%, and thermal conductivity 0.80% W/m °K. Below 145 m at Site 504 and 210 m at Site 505, mean density increases to 1.40 g/cm**3, porosity decreases to 67%, seismic velocity increases to 1.53 km/s, and thermal conductivity increases to values in excess of 1.0 W/m °K. A good correlation between independent measurements of water content and thermal resistivity supports the existence of small but regular variation in the measured parameters on the scale of 10 m and less.

(Table 3) Observations of Mediterranean water lenses in the Eastern North Atlantic

Spreading pattern and mesoscale structure of Mediterranean water outflow in the eastern North Atlantic are studied on the basis of historical hydrographical records. Effect of bottom topography on Mediterranean water distribution is revealed. It is shown that the Mediterranean water outflow is divided into two streams after leaving the Gulf of Cadiz. These are northwestern and southwestern ones; the former is more intensive and spreads in more regular and continuous way. West of the Tejo (Tagus) Plateau it splits into three branches; the most intense of them keeps continuity up to 14°W. The less intensive southwestern stream passes south of the Gettysburg Bank and splits into two branches immediately after the Gulf of Cadiz. From 11°W, this stream has lenticular, intermittent character. West of 14°-15°W all Mediterranean water branches are represented mainly by isolated salty patches. As a result of historical data analysis in the 32°-44°N, 8°-22°W area, 30 Mediterranean water lenses have been found; 12 of them had not been previously mentioned in publications. A table of main parameters of Mediterranean water lenses is presented. It includes data of 108 observations from 1911 to 1993.

Terrain model of the Håkon Mosby Mud Volcano (10 m grid size)

The Håkon Mosby Mud Volcano is a natural laboratory to study geological, geochemical, and ecological processes related to deep-water mud volcanism. High resolution bathymetry of the Håkon Mosby Mud Volcano was recorded during RV Polarstern expedition ARK-XIX/3 utilizing the multibeam system Hydrosweep DS-2. Dense spacing of the survey lines and slow ship speed (5 knots) provided necessary point density to generate a regular 10 m grid. Generalization was applied to preserve and represent morphological structures appropriately. Contour lines were derived showing detailed topography at the centre of the Håkon Mosby Mud Volcano and generalized contours in the vicinity. We provide a brief introduction to the Håkon Mosby Mud Volcano area and describe in detail data recording and processing methods, as well as the morphology of the area. Accuracy assessment was made to evaluate the reliability of a 10 m resolution terrain model. Multibeam sidescan data were recorded along with depth measurements and show reflectivity variations from light grey values at the centre of the Håkon Mosby Mud Volcano to dark grey values (less reflective) at the surrounding moat.

Tab. 1+2: C14-dates cf the older and younger emergence periods

In the neighbourhood of Oobloyah Bay various phenomena ean be eneountered whieh point to a ularge-seale uplift of shorelines, i.e. to an emergence of 200 m. Delta terraces, deltaic fan terraces and glacio-marine sands are regarded by the author as being the most reliable evidence of this. The marine limit documented by glacio-marine sand is to be found at ~170 m a.s.l. Hints of ancient shorelines located at a higher level exist only in the shape of badly preserved raised beaches. They were classified as less reliable records of past sea-levels, due to the lack of marine fossils and/or drift wood, and furthermore because those forms had been strongly influenced by periglacial processes. Deltaic deposits are of more importance in this context. The glacio-marine deltaic sands of several terrace levels contain terrestrial plant remnants which delivered C14dates. Using these dates und the relative elevations of terraces the emergenee of the area investigated could be recorded. This occured in a series of phases (and steps) which were summarized into two periods: an early period of emergenee which took place from at least 25 300 years B.P. to later than 17 340 years B.P. and a later one from at least 12 870 years B.P. up to the present day. The emergence seems to represent a discontinuous but regular sequence of relative sea level movements without intermittent submergence. Since the deltaic fans of the early emergence period were accumulated by sediments through glacio-fluvial channels of an adjacent glacier body the appropriate location of this glacial stage for one of the glaciers delivering meltwater (Nukapingwa Glacier) could be reconstructed. This stage of the glacier appears to belong to a retreating phase of the Mid-Wisconsin (?). The later period of emergence resulted in six rather glacio-marine delta terrace generations at the mouths of the main rivers with glaciofluvial regimen debouching into the Oobloyah Bay. A connection of this emergence with the glacial history of the field area is discussed. If one may rely on the age determinations of land derived plant fossils and their application for the climatic history of the area investigated, it must be concluded that the Heidelberg Valley, to a large extent, was alreaely deglaciated 25 000 years ago. The existence of a "Cockburn"-Phase in the sense of a major readvanee in Late Wisconsin times appears to be doubtful, or has been developed rather weakly.

Water balance measurements on Samoylov Island during campaign Lena2011

The summer water balance of a typical Siberian polygonal tundra catchment is investigated in order to identify the spatial and temporal dynamics of its main hydrological processes. The results show that, besides precipitation and evapotranspiration, lateral flow considerably influences the site-specific hydrological conditions. The prominent microtopography of the polygonal tundra strongly controls lateral flow and storage behaviour of the investigated catchment. Intact rims of low-centred polygons build hydrological barriers, which release storage water later in summer than polygons with degraded rims and troughs above degraded ice wedges. The barrier function of rims is strongly controlled by soil thaw, which opens new subsurface flow paths and increases subsurface hydrological connectivity. Therefore, soil thaw dynamics determine the magnitude and timing of subsurface outflow and the redistribution of storage within the catchment. Hydraulic conductivities in the elevated polygonal rims sharply decrease with the transition from organic to mineral layers. This interface causes a rapid shallow subsurface drainage of rainwater towards the depressed polygon centres and troughs. The re-release of storage water from the centres through deeper and less conductive layers helps maintain a high water table in the surface drainage network of troughs throughout the summer.