The nature of Ordovician limestone-marl alternations in the Oslo-Asker District Norway: witnesses of primary glacio-eustasy or diagenetic rhythmsReportar como inadecuado




The nature of Ordovician limestone-marl alternations in the Oslo-Asker District Norway: witnesses of primary glacio-eustasy or diagenetic rhythms - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

(2016)SCIENTIFIC REPORTS.6. Mark abstract Ordovician limestone-marl alternations in the Oslo-Asker District have been interpreted as signaling glacio-eustatic lowstands, which would support a prolonged "Early Palaeozoic Icehouse". However, these rhythmites could alternatively reflect differential diagenesis, without sedimentary trigger. Here, we test both hypotheses through one Darriwilian and three Katian sections. Our methodology consists of a bed-by-bed analysis of palynological (chitinozoan) and geochemical (XRF) data, to evaluate whether the limestone/marl couplets reflect an original cyclic signal. The results reveal similar palynomorph assemblages in limestones and marls. Exceptions, which could be interpreted as reflecting palaeoclimatological fluctuations, exist at the species level: Ancyrochitina bornholmensis seems to be more abundant in the marl samples from the lower Frognerkilen Formation on Nakkholmen Island. However, these rare cases where chitinozoans differ between limestone/marl facies are deemed insufficient for the identification of original cyclicity. The geochemical data show a near-perfect correlation between insoluble elements in the limestone and the marls, which indicates a similar composition of the potential precursor sediment, also in the Frognerkilen Formation. This is consistent with the palynological data. Although an original cyclic pattern could still be recorded by other, uninvestigated parameters, our palaeontological and geochemical data combined do not support the presence of such a signal.

Please use this url to cite or link to this publication: http://hdl.handle.net/1854/LU-7090142



Autor: Chloé EA Amberg, Tim Collart , Wout Salenbien, Lisa M Egger, Axel Munnecke, Arne T Nielsen, Claude Monnet, Øyvind Hammer and Thi

Fuente: https://biblio.ugent.be/publication/7090142



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