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POLLEN ASSEMBLAGES, PLANT COMMUNITIES AND BIOSTRATIGRAPHY OF THE LOWER PLEISTOCENE CAMPINE CLAY IN BELGIUM.
This paper deals with the palaeobotany and the stratigraphy of the Formation of Weelde, a lithostratigraphical unit grouping the uppermost clays and sands of the Early-Pleistocene Campine Clay, situated in the North of Belgium. This Formation is divided into the Rijkevorsel Clay Member underneath, the Turnhout Clay Member above and the intervening Beerse Sand Member. The pollen analysis of the peaty sediments included in the Rijkevorsel Clay reveals a boreal Pinus-biozone at the bottom, followed by a temperate biozone, dominated by Alnus, and finally ending with another boreal Pinus-zone at the top of the sequence. This vegetational cycle is believed to correspond with an interglacial. The Turnhout clay shows a similar, botanical succession, but incomplete because the lower, boreal Pinus-biozone could not be demonstrated. Nevertheless an interglacial character is attributed to this vegetational cycle. Both Members are separated from each other by the Beerse Member, composed of fluviatile and eolian sands with peat inclusions and displaying cryoturbatic features. Palynologically it shows a threefold alternation of arctic and subarctic episodes. The Beerse Glacial is proposed for this Member. The plant macrofossils, recovered from the peat and peaty sediments, belong to aquatic and marshy plant communities. Noteworthy are the megasporangia of Azolla tegeliensis and Salvinia natans, which occur in all three Members. A comparative study with the Early-Pleistocene deposits in the South of the Netherlands could not remove all the doubts of a correct correlation with the European chronostratigraphy.
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About: Rogier VANHOORNE
Royal Belgian Institute of Natural Sciences, Vautierstreet 29, B-1000 Brussels, Belgium