on the Würm - Flandrian boundary in Deep-sea cores

Abstract

Due to the present drainage pattern the North Atlantic receives much more weathered products than the other oceans do. Dissolutions and oxidations at the bottom of the North Atlantic seem to change in time, being climatologically controlled. The dissolution of carbonates in North Atlantic has been intensified during ice ages mainly in the zone of Polar Bottom Water. During the Main (Upper) Würm the Arctic Ocean was not ice covered because of the absence of a salinity discontinuity (halocline). It is believed that an intense formation of bottom water occurred there and that this water then flushed the North Atlantic bottom and caused the increased dissolution of carbonates. At the transition Alleröd/Younger Dryas (Würm/Flandrian boundary) the Arctic Ocean was covered by a pack-ice. The developed halocline stopped the sink water formation. Then the outflow of cool bottom water to the Norwegian Sea dropped suddenly. The lack of this bottom water caused an increased carbonate deposition in the North Atlantic approximately 11,000 B.P., and somewhat later on, a decrease of it occurred in the Indian and Pacific Oceans (see fig. 1). The isotopic paleotemperature method has been found invalid. The percentages of warmwater-indicating foraminifera suggest that the North Atlantic gradually became warmer from the Alleröd up to the climatic optimum about 6000 B.P. The precipitation in the arid lands around the Gulf of Aden during the late Würm and Flandrian are given in Fig. 6. The highest precipitation during aforementioned times occurred during the Atlantic subage and the lowest one during the Preboreal subage. It is suggested that the Red Sea was dry during maximum of the Main (Upper) Würm Ice age. A marked change in the vertical circulation happened about 8000 B.P. The Eastern Mediterranean and the Cariaco Trench changed into a (quasi)stagnant phase approximately during or at the end of the Alleröd subage. The climatic deterioration during the younger Dryas stadial is explained as caused by the albedo change which occurred when the Arctic Ocean went into the pack ice phase. The duration of this stadial is about 600 yrs. Such a short interval is hard to trace in abyssal cores. The last large change in deepsea cores has probably happened at the end of the Alleröd subage. These two points suggest that the upper boundary of the Würm age is to be placed at the Earlier Dryas - Alleröd boundary. The present age is here called Flandrian since Holocene is a term of higher rank (epoch). I also suggest that Pleistocene should be considered as the only epoch in the euaternary period- "Holocene" could be discarded.