ALBERT

Description: A deep-sea core over 16 m long from the crestal area of the Mediterranean Ridge has been investigated with different techniques, including quantitative micropaleontology, stable isotopes (measured on the epipelagic species Globigerinoides ruber and on the mesopelagic species Globorotalia inflata), and clay mineralogy. The resulting record of climatic fluctuations can be cross correlated to other Mediterranean cores by means of isochronous lithologies (tephra layers and sapropels). The climatic record of the Mediterranean is similar in character, phase, and chronology to the records investigated in the equatorial Pacific and in the Caribbean. Isotope stages 1 to 17 have been recognized. Cyclically repeated stagnant cycles resulting in sapropel deposition complicate both the isotopic and the faunal signal. The isotopic investigations reveal that the temperature change in the surface layers of the eastern Mediterranean was no greater than 8°C in the late “glacial” Pleistocene. The chronostratigraphic and biostratigraphic interpretation of Core KS09 indicate that the mean sedimentation rate was 2.4 cm/1000 years, a value very close to the 2.5 cm/1000 years calculated for the entire Quaternary section at DSDP Site 125, also located in the crestal area of the Mediterranean Ridge in the Ionian Basin. The base of KS09 is likely to be very close to the Brunhes/Matuyama boundary dated at 0.7 my.

Description: Sediment cores from the continental slope off NW Africa (20-27° N) have been investigated by means of an analysis of clay minerals, of grajn size distribution of terrigenous material and of coarse fractions and CaC03 -contents. Deductions concerning Late Quaternary climatic variations could be made from the obtained results. The interglacial periods X and Z (stage 1 and 5 after SHACKLETON & OPDYKE 1973) had an arid climate, characterized by: a) presence of chlorite and attapulgite in noticeable amounts, these fragile minerals being preserved from weathering in dry climatic conditions, b) small grain size of terrigenous material, c) high desert quartz numbers, high CaC03-amounts of total sediment, small terrigenous input and low transport energy. The glacial periods Y and W (stage 2-4 and 6) had a humid climate. This is suggested by: a) the absence or rareness of chlorite and attapulgite and increasing amounts of mixed-layer minerals, b) high amounts of coarse-grained terrigenous material, indicating greater transport energy, c) low or disappearing desert quartz numbers, low CaC03-content and high terrigenous input. The cores from 27 and 20° N do not fit into this general scheme, because they are situated at climatic boundaries, the northern core lying at the actual boundary of mediterranean humid and arid climate, the southern core lying at the Würm boundary between humid and arid climate. Results of 40-63 μm sized desert quartz and amount of 〈6 respectively 20-63 μm fraction show sharp boundaries between stratigraphic zones, revealing rapid changes in climate. Clay mineralogical changes are less rapid, showing the progressive changes in soil formation and soil destruction. The origin of the clay minerals is exclusively detrital. Their quantitative variations show a differential settling with distance from coast, and a latitudinal zonation parallel to terrestrial soils.