Pre-glacial to glacial sediment thickness grids for the Southern Pacific Margin of West Antarctica, NetCDF files

Circum-Antarctic sediment thickness grids provide constraints for basin evolution and paleotopographic reconstructions, which are important for paleo-ice sheet formation histories. By compiling old and new seismic data, we identify sequences representing pre-glacial, transitional and full glacial deposition processes along the Pacific margin of West Antarctica. The pre-glacial sediment grid depicts 1.3 to 4.0 km thick depocenters, relatively evenly distributed along the margin. The depocenters change markedly in the transitional phase at, or after, the Eocene/Oligocene boundary, when the first major ice sheets reached the shelf. Full glacial sequences, starting in the middle Miocene, indicate new depocenter formation North of the Amundsen Sea Embayment and localized eastward shifts in the Bellingshausen Sea and Antarctic Peninsula basins. Using present-day drainage paths and source areas on the continent, our calculations indicate an estimated observed total sedimentary volume of ~10 x 10**6 km**3 was eroded from West Antarctica since the separation of New Zealand in the Late Cretaceous. Of this 4.9 x 10**6 km**3 predates the onset of glaciation and need to be considered for a paleotopography reconstruction of 34 Ma. Whereas 5.1 x 10**6 km**3 postdate the onset of glaciation, of which 2.5 x 10**6 km**3 were deposited in post mid-Miocene full glacial conditions.

Abundance of organic-walled dinoflagellate cysts in surface sediments from the Atlantic sector of the Southern Ocean (Appendix 2)

Thirty-two surface sediment samples from the Southern Ocean (eastern Atlantic sector), between the Subtropical Front and the Weddell Gyre, were investigated to provide information on the distribution of modern organic-walled dinoflagellate cysts in relation to the oceanic fronts of the Antarctic Circumpolar Current (ACC). A clearly distinguishable distribution pattern was observed in relation to the water masses and fronts of the ACC. The dinoflagellate cysts of species characteristic of open oceanic environments, such as Impagidinium species, are highly abundant around the Subtropical Front, whereas south of this front, cosmopolitan species such as Nematosphaeropsis labyrinthus and the cysts of Protoceratium reticulatum characterise the transition from subtropical to subantarctic surface waters. The subantarctic surface waters are dominated by the cysts of heterotrophic dinoflagellates, such as Protoperidinium spp. and Selenopemphix antarctica. The cysts of Protoperidinium spp. form the dominant part of the assemblages around the Antarctic Polar Front, whereas S. antarctica concentrations increase further to the south. The presence of S. antarctica in sediments of the Maud Rise, a region of seasonal sea-ice cover, reflects its tolerance for low temperatures and sea-ice cover. A previously undescribed species, Cryodinium meridianum gen. nov. sp. nov., has a restricted distribution pattern between the Antarctic Polar Front and the ACC-Weddell Gyre Boundary.

Geochemistry of the water column of southern lake Baikal during 1967-2005

At present, when the influence of human economic activity is progressively increasing, significant attention is devoted to the state of water ecosystems. All researchers engaged in these problems agree that the state of the water system (pollution and eutrophication) can only be estimated on the basis of long-term researches. Systemic monitoring (at least once per month) of ionic components (Ca2+, Mg2+, Na+, K+, bicarbonates, sulfates, and chlorides) in unfiltered water of Lake Baikal and its tributaries had been carried out under the supervision of Votintsev since 1947. Based on the analysis of systematic data on trophic components obtained during 1965-2005, we tried to estimate the present-day trophic status of the pelagic zone in the lake, define the trend of long-term changes of trophic components and understand the reasons of the distortion of cyclicity in the development of spring diatom algae, which create a favorable environment in any water basin. It should be noted that the station near Cape Polovinnyi is located 20 km away from the town of Baikal'sk. Wastewaters of the Baikal'sk pulp and paper mill is the main source of dioxins and furans in Baikal. Based on the significant difference between sulfate contents in wastewaters of the plant (>300 mg/l), tributaries of Baikal (7.5 mg/l), and waters in the southern part of the lake (3.9 mg/l), we defined the following periods: (i) period of natural seasonal patterns until 1967-1968 (prior to putting the Baikal'sk Mill into operation; (ii) period of weak anthropogenic pollution (1969-1985); and (iii) period of strong anthropogenic pollution since 1986.

Concentrations of organic carbon and organic matter isotopic compositions of sapropels and adjacent marls from ODP Hole 161-974B in the Tyrrhenian Basin (Table 1)

Multiple layers of sapropels occur widely in the sedimentary record of the Mediterranean Sea and record repetitions of paleoclimatic conditions that favored increased production and preservation of marine organic matter. A combination of hydrogen and carbon isotope analyses of Pleistocene sapropels from the Tyrrhenian Sea reveals new aspects of the factors leading to their deposition. Organic matter dD values that are significantly more negative in sapropels than in adjacent marls indicate a combination of dilution of surface waters by meteoric waters and increased burial of lipid-rich organic matter during periods of sapropel deposition. Organic d13C values in sapropels that are less negative than those in marls suggest periods of markedly elevated marine biological production. The opposite but concordant excursions of these two isotopic parameters imply that the sapropel layers formed from increased export of marine organic matter from the photic zone to the sea floor during periods of greater fluvial delivery of continental nutrients to the Mediterranean Sea. Furthermore, the isotopic evidence indicates that periods of wetter climate were widespread in southern Europe at the same times as in northern Africa.

Geochemistry of sediment cores GeoB4901-3 and GeoB4901-8 from the southern flank of the Niger Fan

Time series of terrigenous source elements (Al, K, Ti, Zr) from core GeoB4901-8 recovered from the deep-sea fan of the Niger River record variations in riverine sediment discharge over the past 245,000 yr. Although the flux rates of all the elements depend on physical erosion, which is mainly controlled by the extent of vegetation coverage in central Africa, element/Al ratios reflect conditions for chemical weathering in the river basin. Maximum sediment input to the ocean occurs during cold and arid periods, when precipitation intensity and associated freshwater runoff are reduced. High carbonate contents during the same periods indicate that the sediment supply has a positive effect on river-induced marine productivity. In general, variations in the terrestrial signals contain a strong precessional component in tune with changes in low-latitude solar radiation. However, the terrestrial signal lags the insolation signal by several thousand years. K/Al, Ti/Al, and Zr/Al records reveal that African monsoonal precipitation depends on high-latitude forcing. We attribute the shift between insolation cycle and river discharge to the frequently reported nonlinear response of African climate to primary orbital configurations, which may be caused by a complex interaction of the secondary control parameters, such as surface albedo and/or thermohaline circulation.

Sea surface temperatures reconstructed from alkenones of surface sediment samples of the Argentine Basin at stations GeoB1501-1 to GeoB2830-1

We analysed the alkenone unsaturation ratio (UK'37) in 87 surface sediment samples from the western South Atlantic (5°N-50°S) in order to evaluate its applicability as a paleotemperature tool for this part of the ocean. The measured UK'37 ratios were converted into temperature using the global core-top calibration of Müller et al. (1998, doi:10.1016/S0016-7037(98)00097-0) and compared with annual mean atlas sea-surface temperatures (SSTs) of overlying surface waters. The results reveal a close correspondence (<1.5°C) between atlas and alkenone temperatures for the Western Tropical Atlantic and the Brazil Current region north of 32°S, but deviating low alkenone temperatures by -2° to -6°C are found in the regions of the Brazil-Malvinas Confluence (35-39°S) and the Malvinas Current (41-48°S). From the oceanographic evidence these low UK'37 values cannot be explained by preferential alkenone production below the mixed layer or during the cold season. Higher nutrient availability and algal growth rates are also unlikely causes. Instead, our results imply that lateral displacement of suspended particles and sediments, caused by strong surface and bottom currents, benthic storms, and downslope processes is responsible for the deviating UK'37 temperatures. In this way, particles and sediments carrying a cold water UK'37 signal of coastal or southern origin are transported northward and offshore into areas with warmer surface waters. In the northern Argentine Basin the depth between displaced and unaffected sediments appears to coincide with the boundary between the northward flowing Lower Circumpolar Deep Water (LCDW) and the southward flowing North Atlantic Deep Water (NADW) at about 4000 m.

Mesozooplankton in Bornholm Basin, Baltic Sea

The seasonal vertical distribution of mesozooplankton was investigated in the Bornholm Basin in October 1988, July 1991 and April 1992 by means of horizontal tows using a small net with a mesh size of 47 micrometers. This study shows that the vertical distribution of multivoltine copepods is linked with ontogeny and may also change seasonally, even in shallow areas such as the Baltic. Trends between copepod species, stages and seasons were discovered. Secondly, the correlation was investigated between the vertical mesozooplankton distribution on the one hand and chlorophyll a concentration and the density of medusae and fish larvae on the other hand. In several cases the comparison of the shape of the profiles led to greater differentiation than the coefficient of correlation. The abundances found allowed only scant statements about non-copepod taxa.

Ground penetrating radar (GPR) and electrical resistivity tomography (ERT) survey on the neotectonic activity of the Padul-Nigüelas Fault Zone (PNFZ), Southern Spain

The Padul-Nigüelas Fault Zone (PNFZ) is situated at the south-western mountain front of the Sierra Nevada (Spain) in an extensive regime and belongs to the internal zone of the Betic Cordilleras. The aim of this study is a collection of new evidence for neotectonic activity of the fault zone with classical geological field work and modern geophysical methods, such as ground penetrating radar (GPR). Among an apparently existing bed rock fault scarp with triangular facets, other evidences, such as deeply incised valleys and faults in the colluvial wedges, are present in the PNFZ. The preliminary results of our recent field work have shown that the synsedimentary faults within the colluvial sediments seem to propagate basinwards and the bed rock fault is only exhumed due to erosion for the studied segment (west of Marchena). We will use further GPR data and geomorphologic indices to gather further evidences of neotectonic activity of the PNFZ.