
Mikael Calner
Professor

Carbonate mud mounds, conglomerates, and sea-level history in the Katian (Upper Ordovician) of central Sweden
Författare
Summary, in English
The Katian (Upper Ordovician) facies succession of the Siljan district, central Sweden, records some of the most prominent environmental changes in the Ordovician of Baltoscandia. These changes include two separate phases of major sea-level drawdown that were of basinwide and presumably global importance. The first regression and lowstand terminated an entire generation of carbonate mud mounds (the Kullsberg Limestone) and resulted in the formation of polymict carbonate conglomerates (SkAyenlberg Limestone) belonging to the Amorphognathus superbus Zone. New stable isotope data from the Amtjarn quarry shows that this is immediately after the peak of the Guttenberg Carbon Isotope Excursion (GICE), which reaches a delta C-13 peak value at 3.3aEuro degrees in the uppermost Amorphognathus tvaerensis Conodont Zone. A second major regression and sea-level lowstand is manifested by palaeokarst morphologies in the Slandrom Limestone, which formed close in time to the comparably minor Waynesville positive carbon excursion in the basal Amorphognathus ordovicicus Conodont Zone. The widespread exposure associated with this latter lowstand terminated carbonate production in much of the basin, and, during the subsequent flooding, organic-rich, graptolitic shale formed across most of Baltoscandia. The two corresponding sequence boundaries are amalgamated at the top of truncated carbonate mud mounds in the Siljan district, resulting in a pronounced Middle Katian hiatus in the immediate mound areas.
Avdelning/ar
- Berggrundsgeologi
Publiceringsår
2010
Språk
Engelska
Sidor
157-172
Publikation/Tidskrift/Serie
Facies
Volym
56
Issue
1
Dokumenttyp
Artikel i tidskrift
Förlag
Springer
Ämne
- Geology
Nyckelord
- Sweden
- Siljan district
- Katian
- Glaciation
- Black shale
- GICE
- Conglomerates
Aktiv
Published
ISBN/ISSN/Övrigt
- ISSN: 0172-9179