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

Evaluation of the Salinic I tectonic, Cancañiri glacial and Ireviken biotic events: Biochemostratigraphy of the Lower Siluriansuccession in the Niagara Gorge area, Canada and U.S.A.

“…8), coincident with the previously cited Ireviken biotic event identified at Gotland (Jeppsson, 1987;Talent et al, 1993;Munnecke et al, 2003) and interpreted to reflect a decrease in hemi-pelagic productivity (e.g., Jeppsson, 1990Jeppsson, , 1998. On Gotland, this event is represented by up to 13 m of faunal changes while at other localities it is marked by sudden changes within a 1 m interval (Munnecke et al, 2003). The fact that the Llandovery-Wenlock carbon isotope shift was observed in brachiopods from North America and Europe suggests a global significance of the signal.…”

“…Subsequently, the band of δ 13 C values becomes heavier, reaching a maximum during graptolite zone 15, particularly in the Niagara Gorge (+ 6.0‰) and at Gotland (+ 6.37‰). As already pointed out, the Ireviken event/excursion is recorded at Gotland (Munnecke et al, 2003;Calner et al, 2004), Estonia (Heath et al, 1998) and the Niagara Gorge area (Fig. 13B), and is therefore of global significance.…”

“…This global 'light' ) for the Llandovery-Wenlock interval using only the 'best' of all materials. Marked also are the tectonic (T) events Salinic I/part II (Ettensohn and Brett, 1998), glacial (G) Cancañiri episode (Hambry, 1985;Grahn and Caputo, 1992;Caputo, 1998) and biotic (B) Ireviken event and excursion (Walliser, 1964;Jeppsson, 1987Jeppsson, , 1998Talent et al, 1993;Munnecke et al, 2003;Calner et al, 2004). The sea level changes in bathymetry are: S -shallow, D -deep (Johnson, 1996;Johnson et al, 1998) and SHS -Silurian highstand (Ettensohn and Brett, 1998).…”

“…This biotic event was recognized from the Lower Silurian faunal changes on the island of Gotland, Sweden (Wilde, 1991). The Niagara Gorge area is located between Ontario and New York State and locations of other studies are: 1) Nevada (Saltzman, 2001), 2) Oklahoma (Ruppel et al, 1996(Ruppel et al, , 1998Saltzman, 2001), 3) Anticosti Island (Wadleigh and Veizer, 1992;Ruppel et al, 1996Ruppel et al, , 1998Azmy et al, 1998Azmy et al, , 1999, 4) Britain (Azmy et al, 1998, 5) Gotland, Sweden (Wadleigh and Veizer, 1992;Wenzel and Joachimski, 1996;Azmy et al, 1998Azmy et al, , 1999Samtleben et al, 2001;Munnecke et al, 2003), and 6) Estonia/Lithuania (Azmy et al, 1998Heath et al, 1998). Arrows are the hypothetical track of currents, c -cold, w-warm (modified from Driese et al, 1991;Wilde et al, 1991;Brett et al, 1998).…”

“…Arrows are the hypothetical track of currents, c -cold, w-warm (modified from Driese et al, 1991;Wilde et al, 1991;Brett et al, 1998). (Walliser, 1964;Jeppsson, 1987Jeppsson, , 1998Munnecke et al, 2003) and is claimed to have been the major biotic crisis of the Silurian Period (Talent et al, 1993). Support for such a view comes from a host of widely distributed locations in Australia, Britain, the Urals, Poland, Estonia and North America (Jeppsson, 1998).…”