Llandovery green/grey and black mudrock facies of the northern Holy Cross Mountains (Poland) and their relation to early Silurian sea-level changes and benthic oxygen level

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• 作者：Wiesław Trela^a ; ^{wieslaw.trela@pgi.gov.pl" class="auth_mail" title="E-mail the corresponding author} ; Teresa Podhalańska^b ; Justyna Smolarek^c ; Leszek Marynowski^c
• 关键词：Silurian ; Llandovery ; Mudrocks ; Anoxia ; Oxygenation ; Sea-level
• 刊名：Sedimentary Geology
• 出版年：2016
• 出版时间：1 August 2016
• 年：2016
• 卷：342
• 期：Complete
• 页码：66-77
• 全文大小：3034 K

文摘

The Llandovery mudrock facies in the northern Holy Cross Mountains reveal lithological variability allowing their interpretation in the context of post-Ordovician climate and sea-level changes in the Caledonian foredeep basin developed along the present SW margin of Baltica. They form a succession up to 50 m thick made up of grey and greenish clayey mudstones interrupted by black shales. The sedimentary and geochemical data (total organic carbon, pyrite framboids and trace metals) clearly show that the black shales document periods of the significant sediment starvation and oxygen- deficient conditions. Their occurrence is confined to the persculptus–acuminatus, vesiculosus, cyphus, convolutus–sedgwickii, turriculatus–crispus, crenulata and spiralis graptolite biozones and they can be correlated with post-glacial transgressions. In contrast, the grey and greenish mudstones are interpreted as lithofacies reflecting permanent benthic oxygenation driven by deep-water ventilation during the Aeronian and Telychian regressions supported by sedimentary and geochemical studies, and diameters of pyrite framboids