Alkali-syenites in Ayrshire

Abstract

IT is now well known that a group of basic alkalic rocks of approximately late Carboniferous or early Permian age occurs in central Scotland. Dr. Teall first remarked the teschenitic affinities of some of these rocks in his “British Petrography” (1888). During the recent work of the Geological Survey in central Scotland, many occurrences of teschenite, essexite, and theralite have been recognised by Mr. Bailey and Dr. Flett. In several localities the teschenites pass into picrites of the Inchcolm type. Although the general facies of this group is quite basic, and locally ultra-basic, the presence of acid veins in some of the teschenite intrusions has encouraged the hope that a more acidic phase might be discovered in some of the lesser known intrusive masses of central Scotland, hitherto indiscriminately lumped together as “dolerites”.