The Ireviken Event in the lower Silurian of Gotland, Sweden - Relation to similar Palaeozoic and Proterozoic events

Munnecke A, Samtleben C, Bickert T, Munnecke A, Munnecke A (2003)

Publication Status: Published

Publication Type: Journal article, Original article

Publication year: 2003


Publisher: Elsevier

Book Volume: 195

Pages Range: 99-124

DOI: 10.1016/S0031-0182(03)00304-3


For a long time, the Silurian was thought to represent a time of stable environmental conditions in the greenhouse period that followed the Late Ordovician glaciation. During the past decade, knowledge about the Silurian has increased markedly and today it is known that the conditions in the Silurian were much more variable than previously assumed. Detailed isotopic investigations have revealed several distinct positive excursions in both carbon and oxygen isotope values. In low latitudes, these periods of high C- and O-isotope values are in many cases characterised by the growth of reefs and the formation of extended carbonate platforms. The sediments deposited during these excursions contain impoverished fossil assemblages, especially with respect to conodonts, graptolites, and trilobites. A conspicuous isotope excursion coincident with facies changes and a marked mass extinction is observed near the Llandovery/Wenlock boundary. This event is called the 'Ireviken Event' after its type locality on the island of Gotland, Sweden (Jeppsson, L., 1987. In: Palaeobiology of Conodonts. Ellis Horwood Ltd., Chichester, pp. 129-145). Here, isotope data from nine sections at the NW coast of Gotland are presented that cover the time interval of the Ireviken Event. The δC mean values rise from +1.4‰ to +4.5‰, and the δO values increase from -5.6‰ to -5.0‰. The relative timing of stable isotope development, extinctions, and facies development is discussed. It is shown that first extinctions precede the isotope excursion. This indicates that extinction events and stable isotope development are only indirectly connected but might reflect the same causes. Other events characterised by similar relationships between positive isotope excursions, mass extinctions, and facies development are found in younger parts of the Silurian (late Wenlock and Ludlow), in the late Ordovician, the late Cambrian, and, with some reservations, in the Proterozoic. The similarities between these events indicate analogous controlling mechanisms. For the Silurian, climatic changes between humid and arid conditions in low latitudes were postulated in an earlier study of the authors. A palaeoceanographic/climatic model was postulated which is consistent with most of the sedimentological, palaeontological, and geochemical data. Here we demonstrate that this model may be applicable also for the older events. © 2003 Elsevier Science B.V. All rights reserved.

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Munnecke, A., Samtleben, C., Bickert, T., Munnecke, A., & Munnecke, A. (2003). The Ireviken Event in the lower Silurian of Gotland, Sweden - Relation to similar Palaeozoic and Proterozoic events. Palaeogeography, Palaeoclimatology, Palaeoecology, 195, 99-124.


Munnecke, Axel, et al. "The Ireviken Event in the lower Silurian of Gotland, Sweden - Relation to similar Palaeozoic and Proterozoic events." Palaeogeography, Palaeoclimatology, Palaeoecology 195 (2003): 99-124.

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