A geochemical drainage survey of the Fleet granitic complex and its environs

Abstract

A regional geochemical drainage reconnaissance programme was undertaken over 900 km2 of south-west Scotland centred on the Fleet granitic complex. Rocks of Ordovician and Silurian age outcrop over the area, into which have been intruded the Fleet and Loch Doon plutons. Multi-element analysis of stream sediments and heavy mineral concentrates shows a number of patterns of trace element distribution related to different lithologies and to mineralisation. Broad scale patterns exhibited by some elements denote compositional variations within the Lower Palaeozoic sediments and within the Fleet and Loch Doon plutons. On thebasis of the drainage data the sedimentary rocks have been divided into eight distinct geochemical units each characterised by different element distribution patterns. The Fleet and Loch Doon plutons have been sub-divided on the same basis. Follow-up investigations of drainage anomalies led to the discovery of both structure-controlled and disseminated base metal mineralisation in the Penkiln drainage basin within the salthernaureole of the Loch Doon granite. The distribution of Cu, F’b and Zn to the south and south-west of the Fleet granite suggests a zonation of vein minerahsation, with Cu prominent adjacent to the granite contact and F’b and Zn having a wider dispersion away from the granite. Other anomalies delineate a mineralised lineament that follows the regional strike of the Lower Palaeozoic sediments, southeast of the Fleet granite