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.