Lower palaeozoic acritarchs as proxies for the reconstruction of palaeoenvironments

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URI: http://nbn-resolving.de/urn:nbn:de:bsz:21-opus-14052
Dokumentart: Dissertation
Date: 2004
Language: English
Faculty: 7 Mathematisch-Naturwissenschaftliche Fakultät
Department: Sonstige - Geowissenschaften
Advisor: Pross, Jörg
Day of Oral Examination: 2004-06-28
DDC Classifikation: 560 - Paleontology; paleozoology
Keywords: Acritarcha , Paläozoikum
Other Keywords: Akritarchen , Palynomorphen , Paläozoikum , Statistik
acritarchs , lower palaeozoic , palaeoenvironment , Palynomorphs
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The Lower Palaeozoic is characterised by a major phytoplankton diversification. Organic-walled organisms (acritarchs) played an essential role in primary production. This group is very useful for biostratigraphy, but has also a high potential for palaeobiogeographical and palaeoecological reconstructions. Late Cambrian, Ordovician and Late Silurian material was studied in order to analyse taxonomy, to review published data and to reconstruct palaeoenvironmental conditions and palaeoclimate . This research led to the publications of six articles attached to the present thesis. Multivariate statistics on Cambro-Ordovician galeate acritarchs from the Algerian Sahara allow an alternative classification . The revision of the genus Nellia from the same succession is based on the combination of traditional taxonomy and statistical approach to demonstrate the high intraspecific variation. For the evaluation of Ordovician acritarch biodiversity, a complete review of the literature has been carried out. The results reflect more regional trends and do not display global diversity patterns. The relation between the morphology of the Cambro-Ordovician galeate acritarchs and environmental parameters (such as salinity) is analysed in comparison with modern dinoflagellate cysts. The acritarch distribution across certain facies boundaries has been investigated on a Late Silurian carbonate platform (Gotland, Sweden). Some acritarch taxa characterise specific palaeoenvironments. The detailed record of climatic changes in the Late Silurian is reflected by changes in the composition of acritarch assemblages from the Gotland succession. The sensitivity of acritarchs to environmental changes may represent an important tool for the reconstruction of the Lower Palaeozoic climate.

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