The Carboniferous of the Outer Moray Firth Basin, quadrants 14 and 15, Central North Sea

Abstract

Analysis of 11 wells in the Outer Moray Firth Basin reveals a thick (up to 600 m) sequence of Forth Formation (Dinantian) clastic lithofacies deposited in a variety of fluvial and lake/bay environments with minor marine influences. A tentative lithostratigraphy for the Dinantian sequence of the Outer Moray Firth is based partly on the correlation of a western volcanic horizon. Palynological results indicate the presence of the Asbian and Brigantian stages, although older Dinantian stages may also be present. A western, relatively sand-poor sequence is dominated by fine-grained lake or bay facies and may possibly contain oil shales. A central and eastern sandstone and coal-rich sequence records the interaction between a fluvial system, possibly a fan delta, and a lake or bay environment. Sediment derivation was probably from the nearby uplands of the Halibut Horst granitoid to the WSW, which may have existed in the hanging wall of a basin-bounding normal fault. The Dinantian of the Outer Moray Firth Basin occurs in the core of a large pre-Permian syncline and resembles contemporaneous sequences seen at outcrop in the eastern Midland Valley of Scotland.