Precambrian gneisses in the Dalradian sequence of northeast Scotland

In this note we draw attention to data which may require major revision of Dalradian stratigraphy and structure in northeast Scotland. The Central Highland sequence of the Dalradian and the Keith Division (Read 1955) of Banffshire are separated from the metasediments of the Banff Division by gneisses. These are referred to as the Cowhythe Gneiss (Read 1923), Queens Hill Gneiss (Harris & Pitcher 1975), Donside and Ellon Gneiss (Read 1955) and Inzie Head Gneiss (Read & Farquhar 1956) after the main areas of outcrop. The reader is referred to Read (1955, pl. 1) where the general distribution of the gneisses is shown. Their relationships to the Central Highland succession are often complicated by the large granitic intrusions of the post-tectonic Younger Granite suite. The generally accepted model for the region interprets the gneisses as migmatites developed from the Ben Lui and Ben Lawers schists (e.g. Read 1955, Harris & Pitcher 1975). Further they are considered to represent the migmatitic core of the Tay Nappe (e.g. Ashworth 1975). Read (1955) originally considered that the rocks of his Banff Division lay on a lag-surface (the Boyne Line) above the gneisses. The great recumbent fold of which the Banff Division formed the upper limb was called the Banff Nappe, and was considered to be a continuation of the Tay Nappe (Read 1955). Recent investigations by the authors reveal a sharp tectonic break between the Dalradian rocks of the Central Highlands/Keith Division and the gneisses. This break is marked by discordance and a major