Gold in the Dalradian terrane : a review of previous work

The Dalradian Supergroup comprises a Late Precambrian sequence of marine clastic sedimentary rocks and minor basic volcanic rocks which was folded and metamorphosed during the early Palaeozoic Caledonian Orogeny. Intrusive igneous rocks are widespread throughout the Dalradian terrane. The most important in terms of gold metallogenesis are the post-tectonic granites which comprise a diverse suite of calc-alkaline intrusions emplaced between 420 and 395 Ma. Numerous occurrences of gold in bedrock and alluvium are documented in the Dalradian terrane of Scotland. Mesothermal vein occurrences are the most important and include the Cononish deposit, near Tyndrum in Perthshire, where planning permission for mining has been granted. Gold mineralisation of several other styles, including intrusion-related, epithermal, stratiform and occurrences associated with mafic-ultramafic intrusions, is also present. This report has been compiled for the BGS Core Programme project ‘Sedimentary Basin Resources: Gold in orogenic extensional basins – the Dalradian’. This project, carried out between 1997–2000, was designed to investigate the factors controlling the distribution of gold in the Dalradian and to develop a predictive metallogenic model for gold mineralisation in this terrane. This report provides a` review of known gold occurrences and the results of past mineral exploration activity in the Dalradian terrane. The latter has been compiled from records held in BGS archives and the available data are summarised in a series of appendices. Exploration for metalliferous mineralisation has been carried out widely in the Dalradian terrane by commercial mining companies and by BGS. In the 1970s most work focused on Cu, Pb, Zn, Ni and Mo, while more recently, from 1981 onwards, precious metals (Au and PGE) were the prime target. Between 1972 and 1984 the DTI sought to encourage private-sector mineral exploration by the provision of grants under the Mineral Exploration and Investment Grants Act (MEIGA). About 150 reports derived from these projects are available on open-file at BGS. Exploration by BGS was carried out mainly through the DTI-funded Mineral Reconnaissance Programme (MRP), which ran between 1972 and 1997. Nearly 150 reports and associated data releases were produced by the MRP. Together the MEIGA and MRP reports have been the major sources of information used in this report. The combination of improved genetic models for gold deposits, the increased availability of multidisciplinary digital geoscience data and the information on previous exploration summarised in this report provides a sound basis for research on gold mineralisation in the Dalradian terrane. Potential exists in a range of settings that may host economic gold deposits.