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

Abstract

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