Crandallite-rich beds of the Libkovice member, most basin, Czech Republic: Climatic extremes or paleogeographic changes at the onset of the Miocene Climatic Optimum?

0547006 - ÚACH 2022 RIV ES eng J - Journal Article
Mach, K. - Rapprich, V. - Faměra, Martin - Havelcová, Martina - Matys Grygar, Tomáš - Novotný, T. - Řehoř, M. - Erban Kochergina, Y. V.
Crandallite-rich beds of the Libkovice member, most basin, Czech Republic: Climatic extremes or paleogeographic changes at the onset of the Miocene Climatic Optimum?
Geologica Acta. Roč. 19, JUL (2021), č. článku 11. ISSN 1695-6133. E-ISSN 1696-5728
Institutional support: RVO:61388980 ; RVO:67985891
Keywords : Crandallite * Isotope geochemistry * Miocene climatic optimum * The Most Basin
OECD category: Environmental sciences (social aspects to be 5.7); Mineralogy (USMH-B)
Impact factor: 1.067, year: 2021
Method of publishing: Open access

We describe the occurrence and possible origin of rare beds 1–10cm thick and containing 20–70% of crandallite, a Ca-Al phosphate enriched in Sr and Ba, found within otherwise monotonous clay-rich lacustrine sediments of the Most Basin in the Central-European Neogene Ohře Rift system. The beds were formed at ca. 17.31, 17.06, and 16.88Ma, while the entire suite of monotonous clays of the Libkovice Member was deposited between 17.46 and 16.65Ma. Trace-element and organic geochemistry, Ar-Ar geochronology and C-O-Sr isotope systematics are used to infer their source and processes leading to their formation. The most enigmatic aspect of the formation of the crandallite beds is the removal of a huge amount of phosphorus from its biogenic cycle in the lacustrine system, which was otherwise stable for ca. 0.8My. Formation of detritus-poor crandallite beds could result from some exceptional environmental disruptions that hindered transport of fine clastic material to the basin floor. Silicic volcanic activity in the area of the Pannonian Basin could have triggered this disruption. Crandallite could provide evidence of long-lasting droughts and acidification of the exogenic environment, as they are roughly coeval with the onset of the Miocene Climatic Optimum at ca. 17.0Ma.
Permanent Link: http://hdl.handle.net/11104/0323371