Mineral investigations at Carrock Fell, Cumbria. Part 2, geochemical investigations

The underlying objective of investigations at
Carrock Fell, under the Mineral Reconnaissance
Programme, was the recognition of the most
effective combination of surface exploration
methods applicable to the discovery of new
deposits in this type of geological environment.
This second report deals with geochemical aspects
of the investigation.
Soil samples were collected from 1199 sites
in an area of 5 km* around the tungsten veins
at Car-rock, and were analysed for Ti, Mn, Fe, Ni,
Cu, Zn, As, Rb, Sr, Zr, MO, Sn, Sb, Ba, W, Pb,
Th and U. The results are presented on geochemical
maps. New areas of mineral potential, to
the north-east of the mine, have been identified
from the coincidence of geochemical anomalies
with strong linear VLF features. High levels of
W, Cu, Zn, As, Rb and Pb and low levels of Sr
are evident in soils above the worked veins.
These elements, with the exception of As,
constitute a broad zone of anomalously high values
to the north and east of the vein system,
accompanied by low Sr values extending up to
1 km east of the worked veins over a distance of
1.2 km north-south. The distribution of As is
exceptional in that a broad halo is apparent for
some 800 m west of the main vein system. Patterns
in the distribution of some elements not related to
the mineralisation clearly reflect compositional
changes of the underlying rocks. Gamma spectrometry
demonstrates a distinct increase in the
K/Th ratios over the main veins and delineates a
potential area of mineralisation to the west of the
mine, coincident with a strong VLF anomaly.
Qualitative contoured maps of count rate for the
U and K channels are effective in delineating the
sub-outcrop of the granite. The geochemical
results and previously reported geophysical results
enabled three areas to be recommended for further
detailed exploration.