Age determination and clay content of sediment core GeoB5804-4

Paleosalinity and terrigenous sediment input changes reconstructed on two sediment cores from the northernmost Red Sea were used to infer hydrological changes at the southern margin of the Mediterranean climate zone during the Holocene. Between approximately 9.25 and 7.25 thousand years ago, about 3 per mil reduced surface water salinities and enhanced fluvial sediment input suggest substantially higher rainfall and freshwater runoff, which thereafter decreased to modern values. The northern Red Sea humid interval is best explained by enhancement and southward extension of rainfall from Mediterranean sources, possibly involving strengthened early-Holocene Arctic Oscillation patterns and a regional monsoon-type circulation induced by increased land-sea temperature contrasts. We conclude that Afro-Asian monsoonal rains did not cross the subtropical desert zone during the early to mid-Holocene.

(Table 3) Relative content of n-alkane groups in samples from hydrothermal fields of the Mid-Atlantic Ridge

Optimum conditions were selected for chromatographic separation of model mixtures of C12-C40 n-alkanes. For one of samples of hydrothermal deposits extraction conditions of hydrocarbons were studied and a sample preparation procedure was selected. The procedure was proposed to determine n-alkanes in samples of hydrothermal deposits by means of gas chromatography - mass spectrometry (GC-MS). Detection limit for n-alkanes was 3x10**-9 to 10**-8% depending on components. On the basis of the proposed procedure composition of n-alkanes was studied in samples of hydrothermal deposits collected at the Mid-Atlantic Ridge (Broken Spur, Lost City, and Rainbow hydrothermal fields). Analyses showed that samples contained C14-C35 n-alkanes. Concentrations of the n-alkanes were rather low and varied from 0.002 to 0.038 µg/g. Hypotheses concerning genesis of identified n-alkanes were offered.

Silt content of two lake records from the Eifel

A comparison of a last interglacial annually laminated and varve counted maar lake record from the Eifel/Germany, with a laminated lake sediment record from Northern Germany shows, that high resolution cores can be correlated across central Europe by dust/loess content, if the resolution of grain size data is on the order of decades/centuries. Phases of widespread dust dispersal are the same as the cold events in the Greenland ice and North Atlantic sea surface temperature patterns. The first occurrence of dust in Northern Germany and in the Eifel is during the Late Eemian Aridity Pulse (LEAP, Sirocko et al. 2005) which is called C26 in ocean records (McManus, same vol.). This cold and arid event occurred exactly at the time of the last glacial inception at 118 kyr. Vegetation change in Northern Germany and the Eifel is out of phase after the LEAP. A taiga/tundra vegetation charcterizes Northern Germany between the LEAP and C24, whereas at the same time a Carpinus dominated temperate forest spread in the Eifel region, comparable to the Carpinus dominated forests in France (Sánchez Goñi et al., 2005). A drastic cooling, associated with widespread aridity, came with the C24 cold event, when the vegetation of central Europe changed to a tundra or shrub tundra.