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Faunal/floral and isotopic responses to Milankovitch precession cyclesand environmental changes in the upper Gulpen Formation (Upper Maastrichtian) at the CBR-Lixhe and ENCI-Maastricht bv quarries Felder, P.J.; Keppens, E.; Declercq, B.; Normand, S.; Streel, M. (2003). Faunal/floral and isotopic responses to Milankovitch precession cyclesand environmental changes in the upper Gulpen Formation (Upper Maastrichtian) at the CBR-Lixhe and ENCI-Maastricht bv quarries. Geol. Mijnb. 82(3): 275-281
In: Netherlands Journal of Geosciences. Kluwer/Cambridge University Press: Den Haag, Cambridge. ISSN 0016-7746; e-ISSN 1573-9708, meer
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Belgium, Visé [Marine Regions]; Netherlands, Maastricht Marien/Kust |
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Abstract |
At ENCI, palynological, bioclast and stable isotope results of the carbonate phase (mainly consisting of coccoliths) co-vary remarkably, displaying two cycles which may be interpreted tentatively as climatic fluctuations. The partial derivative(18)O curve varies roughly between -1.6parts per thousand and -1.1parts per thousand (on PDB scale), corresponding to a temperature change of about 2degreesC. Less negative values (i.e. cooler seawater) coincide with larger amounts of pollen of Normapolles and Triporates type assumed to represent temperate forest elements of a vegetation also containing tropical elements such as palms. Assuming the 5 cm sample intervals at ENCI to correspond to 1 ka, climatic maxima (and minima) may be 20-25 ka apart, obviously recalling Milankovitch precession cycles. These are independent of a sharp sedimentological change noted in the upper part of the lowest cycle (samples 42 to 24). Upwards of sample 42, bioclast contents increase and dinocysts, Spiniferites in particular, decrease significantly, corresponding to a marked shallowing. This turning point is also recorded in the partial derivative(13)C curve at ENCI. Bioclast percentages appear to follow composite trends that are influenced by both climatic and sedimentological conditions. |
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