Characterising As–Bi–Co–Cu-bearing minerals at Scar Crags and Dale Head North, Lake District, UK

Abstract

Scar Crags and Dale Head North in the English Lake District host mineralised veins enriched in ‘Energy Critical Elements’ (ECEs) specifically, bismuth, cobalt and copper. A limited number of studies in the 1970s investigated the mineralogy and inferred the genesis of these veins as being related to the intrusion of the Lake District batholith. This study investigates the geology, mineralogy, composition and paragenesis of these two mineralised areas. The results highlight the ubiquitous presence of Co–Fe–Ni-sulfarsenides in both deposits and the presence of some mineral species, hitherto unreported. Scar Crags samples contained high concentrations of cobalt, commonly present within arsenopyrite, whereas cobalt is of minor importance at Dale Head North, where copper and arsenic are the primary metals. A sequence of events, with As–Co–Ni-bearing fluids infilling the veins after an initial stage of quartz and chlorite precipitation is the most striking resemblance between the two mineralised systems, potentially indicating a common process for Co-rich vein-type deposits in the area. If so, understanding such processes could prove vital in aiding exploration in other terranes.

The applicability of G-BASE stream sediment geochemistry as a combined geological mapping, and prospective exploration tool for As-Co-Cu-Ni mineralisation across Cumbria, UK.

“…The Lake District As-Co-Cu-Ni mineralisation is associated with the emplacement of the aforementioned underlying batholith (Firman & Lee. 1986;Stone et al 2010), with the Scar Crags mineralisation relating to slightly shallower batholith topography and Dale Head North to slightly higher (Solferino et al 2021). The ores were formed most likely from a mixing of magmatic fluids, originated from the intrusive body, and meteoric fluids that circulated through the SKD and BVG (Stanley and Vaughan.…”

“…As defined in the 2015 Paris Climate Agreement, the goal of societal carbon-neutrality by minimum 2050 requires an increased global production of Plug-in Hybrid Electric Vehicles (PHEV), critical to this being the supply of Energy Critical Elements (ECEs) such as Ag, Al, Cr, Co, Cu, Fe, In, Li, Mn, Mo, Nd, Ni, Pb, V, and Zn (Darton Commodities Ltd. 2020;Hund et al 2020;Dehaine et al 2021;Tabelin et al 2021). Cobalt (Co), in particular, is used in various industries related to the production of renewable technologies including PHEV, Li-Co batteries, and high-strength magnets (Alves et al 2018;Dehaine et al 2021;Solferino et al 2021). There is a current monopolisation of global supplies with 69 % of 2020 global Co mining from the Democratic Republic of Congo (DRC) (Gulley.…”

“…Mineralisation is varied across Cumbria but is typically categorised into Baryte, Co, Cu, Graphite, Haematite, Sb, Pb (+Zn) and W occurring as a mixture of skarns, greisens, sedimentary ores, and mineralised veins (Stanley & Vaughan. 1982a, 1982bIxer et al 1979;Solferino et al 2021). The hypogene mineralisation episodes are believed to have occurred between the Middle Ordovician (Dapingian Stage -470 Ma) and the Lower Jurassic .…”

“…1992). The SKD and BVG are the main host groups, with vein-type As-Co-Cu-Ni mineralisation at Scar Crags and Dale Head North (Solferino et al 2021), and minor Co-occurrences noted at Seathwaite and Ulpha (Ixer et al 1979;Stanley & Criddle. 1979;Stanley & Vaughan.…”

“…The ores were formed most likely from a mixing of magmatic fluids, originated from the intrusive body, and meteoric fluids that circulated through the SKD and BVG (Stanley and Vaughan. 1982a;Solferino et al 2021). Numerous, regional scale structures were formed across the Lake District from the Caledonian Orogeny.…”