Palaeocurrents in the Silurian Slite Marl of Fårö, Sweden

Abstract

Abstract In the Wenlockian Slite Marl in the Haganäs 1 and Fårö Kyrka 2 areas on Fårö representatives of several groups of fossils are bimodally oriented, some significantly towards the SE. The macrofauna at Haganäs 1 is composed mainly of tentaculitids and bryozoans but also includes remains of trilobites, brachiopods and crinoids. The orientation of the fossil groups is interpretated as being caused by a gravity-current underflow which swept along the bottom towards the SE. The current which probably carried a large proportion of mud instantly buried the benthic fauna. This conclusion is based on the preservation of the orientation of the tentaculitids and is further supported by the orientation and the preservation of two of the crinoids. These crinoids were most probably buried alive since their plates are articulated. The significance of the orientations is evaluated by means of the chi-square procedure, and the Rayleigh test of randomness.