Early Ludlow (Silurian) graptolites from Skåne, southern Sweden

Abstract: The Colonus Shale consists of light grey, greenish or bluish shale with some carbonate. At some localities mica and thin layers of grey limestone are also present. The Colonus Shale has an estimated thickness of 600-1100 m in Skåne. Early Ludlow graptolites from the Colonus Formation are described from seven localities in the province of Skåne, southernmost Sweden. Some of these limestone localities have been described before, about 100 years ago, and thus needs an update. Earlier data from the localities are discussed and correlated with those of the present study. Samples from six of the discussed localities have been examined, ranging in size from pebbles to small boulders. Neodiversograptus nilssoni, which was reported from Skarhult 1, is identified as Lobograptus progenitor. The old designation of the Skarhult fauna belonging in the nilssoni Zone is correlated to the progenitor Zone. The occurrence of Colonograptus colonus, in Röddinge 1 and 2, Billinge 2 and Bäretofta 1, demonstrates that the strata are of Gorstian, early Ludlow, age. C. colonus also occur in Skillinge 1, but along with Lobograptus scanicus and therefore this strata could be younger than the localities mentioned above, although still of Gorstian age. Pinedalen 1 probably has a younger fauna than the other limestone localities, which is partly based on graptolite strata. The identified graptolite faunas agree well with faunas described from: Poland, the Czech Republic and Britain. Graptolites in limestone can be correlated with other faunas, for example: conodont- , brachiopod- and chitinozoan faunas, to give an even better zonation. A comparison is made between graptolite zonation in Skåne, in late Wenlock to early Ludlow, to conodont zonation on Gotland and chitinozoan zonation in Skåne.