Crandallite-rich beds of the Libkovice Member, Most Basin, Czech Republic : climatic extremes or paleogeographic changes at the onset of the Miocene Climatic Optimum?
Mach, Karel (Severočeské doly a.s)
Rapprich, Vladislav (Czech Geological Survey)
Faměra, Martin (Institute of Inorganic Chemistry of the Czech Academy of Sciences)
Havelcová, Martina (Institute of Rock Structure and Mechanics of the Czech Academy of Sciences)
Grygar, Tomáš Matys (Institute of Inorganic Chemistry of the Czech Academy of Sciences)
Novotný, Tomáš (Severočeské doly a.s.)
Řehoř, Michal (Brown Coal Research Institute, Inc.)
Kochergina, Yulia Erban (Czech Geological Survey)

Date:	2021
Abstract:	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.
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan aquestes es distribueixin sota la mateixa llicència que regula l'obra original i es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Miocene climatic optimum ; The Most Basin ; Crandallite ; Isotope geochemistry
Published in:	Geologica acta, Vol. 19 (2021) , p. 1-29 (Articles) , ISSN 1696-5728

Adreça original: https://raco.cat/index.php/GeologicaActa/article/view/392308
Adreça alternativa: https://revistes.ub.edu/index.php/GEOACTA/article/view/32206
DOI: 10.1344/GeologicaActa2021.19.11

42 p, 12.1 MB

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