Pollen analysis of surface sediments from the Gulf of Guinea and offshore NW-Africa

The areas of marine pollen deposition are related to the pollen source areas by aeolian and fluvial transport regimes, whereas wind transport is much more important than river transport. Pollen distribution patterns of Pinus, Artemisia, Chenopodiaceae-Amaranthaceae, and Asteraceae Tubuliflorae trace atmospheric transport by the northeast trades. Pollen transport by the African Easterly Jet is reflected in the pollen distribution patterns of Chenopodiaceae-Amaranthaceae, Asteraceae Tubuliflorae, and Mitracarpus. Grass pollen distribution registers the latitudinal extension of Sahel, savannas and dry open forests. Marine pollen distribution patterns of Combretaceae-Melastomataceae, Alchornea, and Elaeis reflect the extension of wooded grasslands and transitional forests. Pollen from the Guinean-Congolian/Zambezian forest and from the Sudanian/Guinean vegetation zones mark the northernmost extension of the tropical rain forest. Rhizophora pollen in marine sediments traces the distribution of mangrove swamps. Only near the continent, pollen of Rhizophora, Mitracarpus, Chenopodiaceae-Amaranthaceae, and pollen from the Sudanian and Guinean vegetation zones are transported by the Upwelling Under Current and the Equatorial Under Current, where those currents act as bottom currents. The distribution of pollen in marine sediments, reflecting the position of major climatic zones (desert, dry tropics, humid tropics), can be used in tracing climatic changes in the past.

Sea surface temperature reconstructions of sediment cores from the Atlantic sector of the Southern Ocean

Late Quaternary summer sea surface temperatures (SSTs) have been derived from radiolarian assemblages in the East Atlantic sector of the Southern Ocean. In the subantarctic and the polar frontal zone, glacial SSTs (oxygen isotope stages 2, 4, 6, and 8) were 3°-5°C cooler than today, indicating northward displacements of the isotherms about 2°-4° of latitudes. During interglacials, SSTs almost reached modern levels (oxygen isotope stages 7 and 9) or exceeded them by 2°-3°C (oxygen isotope stages 1 and 5.5). In the subantarctic Atlantic Ocean, changes in SST and calcium carbonate content of the sediment precede variations in global ice volume in the range of the main Milankovitch frequencies. Comparisons with the timing of North Atlantic Deep Water (NADW) proxy records suggests that this early response in the subantarctic Atlantic Ocean is not triggered by the flux of NADW to the Southern Ocean.

Sea-surface temperature reconstruction for sediment core GIK18287-3 in the tropical South China Sea

The timing and magnitude of sea-surface temperature (SST) changes in the tropical southern South China Sea (SCS) during the last 16,500 years have been reconstructed on a high-resolution, 14C-dated sediment core using three different foraminiferal transfer functions (SIMMAX28, RAM, FP-12E) and geochemical (Uk'37) SST estimates. In agreement with CLIMAP reconstructions, both the FP-12E and the Uk'37 SST estimates show an average late glacial-interglacial SST difference of 2.0°C, whereas the RAM and SIMMAX28 foraminiferal transfer functions show only a minor (0.6°C) or no consistent late glacial-interglacial SST change, respectively. Both the Uk'37 and the FP-12E SST estimates, as well as the planktonic foraminiferal delta18O values, indicate an abrupt warming (ca. 1°C in <200 yr) at the end of the last glaciation, synchronous (within dating uncertainties) with the Bølling transition as recorded in the Greenland Ice Sheet Project 2 (GISP2) ice core, whereas the RAM-derived deglacial SST increase appears to lag during this event by ca. 500 yr. The similarity in abruptness and timing of the warming associated with the Bølling transition in Greenland and the southern SCS suggest a true synchrony of the Northern Hemisphere warming at the end of the last glaciation. In contrast to the foraminiferal transfer function estimates that do not indicate any consistent cooling associated with the Younger Dryas (YD) climate event in the tropical SCS, the Uk'37 SST estimates show a cooling of ca. 0.2-0.6°C compared to the Bølling-Allerød period. These Uk'37 SST estimates from the southern SCS argue in favor of a Northern Hemisphere-wide, synchronous cooling during the YD period.

Fluor and opal in surface sediment from the Bransfield Strait (Table 1)

The influence of biogenic opal sediment input (mainly diatom skeletons) on the fluorine budget of marine sediments will be shown for 24 sampling stations of the antarctic regions of Bransfield Strait, Powell Basin, South Orkney Plateau and northwestern Weddell Sea. 4 bulk samples, one from each sedimentation area, contain 9 to 28 wt.-% of biogenic opal , the clay fraction of the 24 samples investigated have 2 to 82 wt.-%. The fluorine concentration in the amorphous biogenic component is 15 ppm. 300 to 800 ppm of fluorine were measured in the clay fractions, 330 to 920 ppm in their lithogenic components. Biogenic opal causes a decrease in fluorine concentration of the sediment by a considerable amount: 6 to 56 % relative to the clay fraction, due to the proportions involved. Biogenic opal is therefore taken into account as a 'diluting' factor for the fluorine budget in marine sediments.

(Tables 2, 3) Element ratios of planktonic foraminifera from western Pacific surface sediments

Accurately quantifying deep-sea calcite dissolution is crucial for understanding the role of the marine carbonate system in regulating atmospheric pCO2 over millennia. We compare a foraminifer-fragmentation-based calcite dissolution proxy (Globorotalia menardii fragmentation index (MFI)) to Mg/Ca, Sr/Ca, and Mg/Sr in several species of deep dwelling planktonic foraminifers. We conducted microfossil and geochemical analyses on the same core top samples taken at different depths on the Ontong Java Plateau to maximize the dissolution signal and minimize the temperature overprint on our data. We also compare elemental ratios from planktonic foraminifer tests to modern bottom water [CO3]2- undersaturation and model-derived estimates of percent calcite dissolved in deep-sea sediments. We find clear linear decreases in Mg/Ca or Mg/Sr in G. menardii and Pulleniatina obliquiloculata with increasing (1) bottom water [CO3]2- undersaturation, (2) percent calcite dissolved in sediments calculated with biogeochemical modeling, (3) MFI, and (4) percent calcite dissolved derived from MFI. These findings lend further support to MFI as a calcite dissolution proxy for deep-sea sediments. In contrast, we find no significant correlation between Sr/Ca and independent dissolution indicators. Our results suggest that Mg/Ca and Mg/Sr from deep dwelling foraminifers could potentially be used as calcite dissolution proxies in combination with independent water temperature estimates. Likewise, establishing the relationship between MFI and dissolution-induced changes in the Mg/Ca of surface-dwelling foraminifers could provide a tool to correct Mg/Ca-derived sea surface temperature reconstructions for calcite dissolution.

Dinoflagellate cysts in surface sediment samples of METEOR cruises M20/2, M23/1, M34/1, M34/2, M34/3 and M34/4

To enhance the limited information available about the palaeo-ecological significance of calcareous dinoflagellates, we have studied their lateral distribution in surface sediments of the equatorial and south Atlantic between 13°N and 36°S. Calcareous dinoflagellate cysts appear to be widely distributed throughout the studied area. In the surface sediments, concentrations (cyst per gram dry sediment) of the vegetative stage Thoracosphaera heimii are generally higher than that of the (presumably) calcareous resting cysts. Distribution patterns in surface sediments of Orthopithonella granifera (Fütterer) Keupp and Versteegh, Rhabdothorax spp. Kamptner., Sphaerodinella albatrosiana (Kamptner) Keupp and Versteegh S. albatrosiana praratabulated, Sphaerodinella tuberosa var. 1 (Kamptner) Keupp and Versteegh and S. tuberosa var. 2 and the ratios between these species have been compared with temperature, salinity, density and stratification gradients in the upper water column. Rhabdothorax spp. is characteristically present in sediments of more temperate regions characterized by high seasonality. Dinoflagellates producing these cysts are able to tolerate high nutrient concentrations, and mixing of the water column. S. albatrosiana is abundant in regions characterized by high sea surface temperatures and oligotrophic surface water conditions. In contrast, the distribution of S. tuberosa var. 2 is negatively related to temperature. The other cyst species did not show a characteristic pattern in relation to the studied environmental gradients. The ratio of Sphaerodinella tuberosa var. 2 to Orthopithonella granifera can be used for reconstructing the presence of stratification in the upper 50 m of the water column, whereas the ratios of S. tuberosa var. 2 to Sphaerodinella albatrosiana and of O. granifera to Rhabdothorax spp. might be used for palaeotemperature reconstructions. Calcareous dinoflagellate cysts are abundant in oligotrophic areas and may be useful for the reconstruction of palaeoenvironmental conditions.

Geochemistry and sedimentation rates of ODP Leg 199 sites and of surface sediments in the eastern Pacific ocean

We present the first high-resolution organic carbon mass accumulation rate (MAR) data set for the Eocene equatorial Pacific upwelling region, from Sites 1218 and 1219 of the Ocean Drilling Program. A maximum Corg MAR anomaly appears at 41 Ma and corresponds to a high carbonate accumulation event (CAE). Independent evidence suggests that this event (CAE-3) was a time of rapid cooling. Throughout the Eocene, organic carbon burial fluxes were an order of magnitude lower than fluxes recorded for the Holocene. In contrast, the expected organic carbon flux, calculated from the biogenic barium concentrations for these sites, is roughly equal to modern. A sedimentation anomaly appears at 41 Ma, when both the measured and the expected organic carbon MAR increases by a factor of two-three relative to the background Eocene fluxes. The rain of estimated Corg and barium from the euphotic zone to the sediments increased by factors of three and six, respectively. We suggest that the discrepancy between the expected and measured Corg in the sediments is a direct consequence of the increased metabolic rates of all organisms throughout the Eocene oceans and sediments. This hypothesis is supported by recent work in ecology and biochemical kinetics that recognizes the fundamental basis of ecology as following from the laws of thermodynamics. This dependence is now elucidated as the Universal Temperature Dependence (UTD) "law" of metabolism and can be applied to all organisms over their biologically relevant temperature range. The general pattern of organic carbon and barium deposition throughout the Eocene is consistent with the UTD theory. In particular, the anomaly at 41 Ma (CAE-3) is associated with rapid cooling, an event that triggered slower metabolic rates for all organisms, slower recycling of organic carbon in the water and sediment column, and, consequently, higher deposition of organic carbon in the sediments. This "metabolism-based" scenario is consistent with the sedimentation patterns we observe for both Sites 1218 and 1219.

Statistical grain size parameter of surface samples from Kiel Bay

Geological observations, using "free-diving" techniques (Figure I) were made in September, 1960 and March 1961 along two continuous profiles in the outer Kiel Harbor, Germany and at several other spot locations in the Western Baltic Sea. A distinct terrace, cut in Pleistocene glacial till, was found that was covered with varying amounts and types of recent deposits. Hand samples were taken of the sea-floor sediments and grainsize distribution determined for both the sediment as a whole and for its heavy mineral fraction. From the Laboratory and Field observations it was possible to recognize two distinct types of sand; Type I, Sand resulting from transportation over a long period of time and distance and Type 11, Sand resulting from little transportation and found today near to xvhere it was formed. Several criterea related to the agent of movement could be used to classify the nature of the sediment; (1) undisturbed (the sediment Cover of the Pleistocene Terrace is essentially undisturbed), (2) mixed by organisms, (3) transported by water movements (sediment found with ripple marks, etc., and (4) "Scoured" (the movement of individual particles of sediment from around larger boulders causes a slow downward movement or "Creeping" which is due to both the force of gravity and bottom currents. These observations and laboratory studies are discussed concerning their relationship to the formation of residual sediments, the direction of sand transportation, and the intensive erosion on the outer edge of the wave-cut platform found in this part of the Baltic Sea.

Benthic foraminifera in surface sediments of the Persian Gulf

During "Meteor"cruise 1965 the author collected 134 samples of surface sediments from the Iranian part of the Persian Gulf. Benthic Foraminifera populations have been analysed for determining their depth zonation. These data are supposed to allow detailed depth interpretation of Pleistocene sediments found in cores. In addition, the ecological information might be usefull to reconstruct the depositional environment of fossil sediments in similar shallow epicontinental seas. The investigation is published in two parts: the present part 1 contains the catalogue of species with short discussions of taxonomic problems, notes on the distribution within the Persian Gulf and 11 plates, partly with scanning electron micrographs. The results of the statistical analysis are given in data tables which include number of species, percentages of 2 (and 5) ranked species, standing crop and foraminiferal numbers. The author used "species groups" to avoid ambiguities with species requiring additional taxonomic studies. However, species numbers within these units are estimated to yield applicable diversity information. - A total of 52 species and 7 "species groups" were separated, 2 new species were described.