'Institute of Geological Sciences of the National Academy of Sciences of Ukraine'
Abstract
Five boreholes in the vicinity of the ancient Ag-Ni-Pb
mine at Hilderston, near Bathgate have yielded new
stratigraphic, mineralogical and geochemical information.
These results, together with a critical reexamination
of old records, are interpreted in relation to a
palaeo-environment profde across a volcanic island with
coastal lagoon and fringing reef deposits, as proposed by
Jameson (1980).
Stratabound Zn-Pb mineralisation occurs in the lower,
argillaceous part of the Petershill Limestone, which was
deposited in an anaerobic lagoon on the edge of a volcanic
landmass during the Lower Carboniferous Epoch (Lower
Limestone Group, Vi&an Stage). The best intersection
shows 8 m of mineralised limestone, with underlying carbonaceous
mudstone (1 m) and tuffaceous seat rock
(2 m), having an average concentration of 0.14 % Pb and
0.66% Zn and maximum values of 0.6% Pb and 3.1%
Zn in the carbonaceous mudstone. Further drilling was
subsequently carried out in order to investigate possible
lateral extensions of the stratabound mineralisation and to
test for mineralisation in similar lithologies and geological
environments at other stratigraphic levels, and a report
on the results will be available at Edinburgh.
Late-Carboniferous hydrothermal veins occur within
the Petershill Limestone and in immediately overlying
elastic sediments, where they are cut by E-W faults and
quartz-dolerite dykes. At Hilderston Mine two
assemblages are recognised in the vein: Ba-Fe-
Ni-Co-Ag-As on a dyke margin adjacent to the elastic
sediments and Fe-Pb-Zn-S at lower levels adjacent to
the limestone. Zones of alteration in the dolerite dykes
carry hydrocarbons and weak Ba-Fe-Cu-F mineralisation.
No potentially-valuable vein deposits were
discovered in the present investigation