Mass occurrence of the large solitary rugose coral Phaulactis angusta at the boundary Lower/Upper Visby Formation in the Silurian of Gotland, Sweden: palaeoecology and depositional implications
Adomat F, Munnecke A, Kido E (2016)
Publication Language: English
Publication Status: Published
Publication Type: Journal article, Original article
Publication year: 2016
Journal
Publisher: Taylor and Francis Ltd.
Book Volume: 138
Pages Range: 393-409
Journal Issue: 3
URI: http://www.tandfonline.com/doi/full/10.1080/11035897.2015.1103780?scroll=top≠edAccess=true
DOI: 10.1080/11035897.2015.1103780
Abstract
The boundary between the Lower and Upper Visby formations on Gotland (Sweden), which roughly correlates with the Llandovery–Wenlock boundary, is characterised by a mass occurrence of the large solitary rugose coral Phaulactis angusta. This coral-rich layer can be followed for some 50 km along the north-west coast of Gotland. The mass occurrence coincides with the onset of a pronounced, globally recognised δC and δO excursions in the lower Sheinwoodian. Altogether 31 specimens of P. angusta from eight localities were examined. We demonstrate that the corals preferred to grow in an upright position. Attachment structures were not observed, and therefore a liberosessile life strategy is suggested. Some corallites show an abrupt change in growth direction accompanied by a decrease in diameter. These features mostly occur in later growth stages and may be explained by disturbances in the growth due to toppling or tilting of the corals. Many specimens were able to change their growth axes, but finally died after such an event. Most specimens in the outcrops show a flattened upper surface, which is interpreted as a result of post-mortem abrasion. Epibiontic bryozoan encrustation took place mostly while the corals where alive, whereas stromatoporoid encrustation and Trypanites borings occurred post-mortem. The repeated growth, tilting and erosion of the corallites of P. angusta demonstrate that the Phaulactis layer represents a condensed interval, characterised by multiple pulses of sediment accumulation and erosion.
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APA:
Adomat, F., Munnecke, A., & Kido, E. (2016). Mass occurrence of the large solitary rugose coral Phaulactis angusta at the boundary Lower/Upper Visby Formation in the Silurian of Gotland, Sweden: palaeoecology and depositional implications. GFF, 138(3), 393-409. https://dx.doi.org/10.1080/11035897.2015.1103780
MLA:
Adomat, Friederike, Axel Munnecke, and Erika Kido. "Mass occurrence of the large solitary rugose coral Phaulactis angusta at the boundary Lower/Upper Visby Formation in the Silurian of Gotland, Sweden: palaeoecology and depositional implications." GFF 138.3 (2016): 393-409.
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