Sedimentology of Upper Ordovician regressive strata in Västergötland

Abstract

Abstract The sedimentology of the upper Ashgillian Dalmanitina Beds in the Billingen-Falbygden area in Vastergotland is studied. They exhibit facies of shallow-water type. In contrast, the underlying Ulunda, Jonstorp and Nittsjo formations (‘Tretaspis Shales’) and the overlying Llandoverian Rastrites Shale were formed in notably deeper water. A possible explanation for the short-term shallowing, which was accompanied by the development of bahamitic sediments, such as peloids and ooids, would be that a large mass of water became bound in the ice cap that covered part of Gondwanaland.