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Redox geochemistry of the red ‘orthoceratite limestone’ of Baltoscandia: Possible linkage to mid-Ordovician palaeoceanographic changes
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SYSNO ASEP 0542527 Druh ASEP J - Článek v odborném periodiku Zařazení RIV J - Článek v odborném periodiku Poddruh J Článek ve WOS Název Redox geochemistry of the red ‘orthoceratite limestone’ of Baltoscandia: Possible linkage to mid-Ordovician palaeoceanographic changes Tvůrce(i) Bábek, O. (CZ)
Kumpan, T. (CZ)
Calner, M. (SE)
Šimíček, D. (CZ)
Frýda, J. (CZ)
Holá, M. (CZ)
Ackerman, Lukáš (GLU-S) RID, SAI, ORCID
Kolková, K. (CZ)Číslo článku 105934 Zdroj.dok. Sedimentary geology. - : Elsevier - ISSN 0037-0738
Roč. 420, July 2021 (2021)Poč.str. 16 s. Jazyk dok. eng - angličtina Země vyd. NL - Nizozemsko Klíč. slova Marine red beds ; Early diagenesis ; Redox gradients ; Laser ablation ICP-MS ; Sea-level changes ; Carbon isotope geochemistry Obor OECD Geology Způsob publikování Omezený přístup Institucionální podpora GLU-S - RVO:67985831 UT WOS 000659165600010 EID SCOPUS 85106313858 DOI 10.1016/j.sedgeo.2021.105934 Anotace The orthoceratite limestone of the Ordovician epicontinental sea of Baltoscandia is one of the oldest Phanerozoicexamples of pelagic marine red beds (MRBs). Being enriched in authigenic haematite, MRBs are considered to besensitive palaeoceanographic redox indicators. In this paper, the origin of the reddening of the Ordovician MRBsand its timing and redox conditions were addressed at two sections, and in a drill core in the Kinnekulle area, Sweden, through the application of diffuse reflectance spectroscopy, sedimentary petrology (microfacies andelectron microprobe), bulk-rock and in-situ element geochemistry (laser-ablation ICP-MS) and molybdenumstable isotope systematics. Enrichment in haematite (up to ~0.05 wt%) occurred during very early diagenesisunder low sedimentation rates (~5 mm/kyr), which is comparable to several examples of Phanerozoic MRBs.The reddening was associated with the mm-scale, in-situ mobility of Fe, Mn, As, Mo and U, due to Fe–Mnredox cycling between primary and secondary minerals and pore water under oxic and suboxic to anoxic condi-tions, it was not related to significant changes in seawater chemistry. Stratigraphic red-to-grey transitions likelycoincided with two mid-Darriwilian global regressions (the so-called Täljsten and at the base of the GullhögenFormation), likely due to the effects of changing sedimentation rates and sub-bottom redox potentials. The Ordo-vician MRBs coincided with a positiveδ13C excursion during the middle Darriwilian, which is different to MRBexamples cited from the Devonian to the Cretaceous age, which frequently coincide with shifts to lower valuesofδ13C. Although MRBs are believed to show a time-specific occurrence in greenhouse or transitionalgreenhouse-to-icehouse climatic modes by several authors, our study suggests that causal links between MRBsand global carbon cycle remain unclear. Pracoviště Geologický ústav Kontakt Jana Popelková, popelkova@gli.cas.cz, Sabina Janíčková, Tel.: 233 087 272 Rok sběru 2022 Elektronická adresa https://www.sciencedirect.com/science/article/pii/S0037073821000865
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