Investigations of small intrusions in southern Scotland

Sixteen small intrusions and one mineral occurrence were examined briefly for indications of disseminated mineralisation. Stream sediment and panned concentrate samples were collected from streams crossing some of the intrusions to supplement existing coverage, and geophysical surveys were conducted over Priestlaw, Cockburn Law and Lamberton Moor. Rock samples collected at some of the localities were analysed for major and trace elements. The intrusive rocks range in composition from granite to diorite and in grain size from hypabyssal to plutonic types. The larger intrusions at Portencorkrie, Priestlaw and Cockburn Law are zoned. Hydrothermal alteration, in places with associated pyrite, was recorded at Mains of Dhuloch, Mochrum, Priesthope, Lamberton Moor, Broad Law, Glenluce, Priestlaw, Cockburn Law and Mull of Galloway, and significant copper enrichment was recorded at the last four of these. It is concluded, however, that in no case is there a likelihood of there being porphyry copper style mineralisation at or near surface. An old copper mine at Tonderghie (Burrow Head) worked a vein system along a fault within Silurian sedimentary rocks.