North Pennine Project, England
Minco has commenced a new exploration initiative in the North Pennine Orefield located in the northern English counties of Cumbria, Northumberland and Durham. Minco has completed 5,800 metres of exploration drilling to date centred around the historical mining town of Nenthead.
The North Pennine Orefield
The North Pennine Orefield forms the largest area of carbonate-hosted lead-zinc mineralisation within the British Isles after the Midland Orefield of Ireland. It covers an area of approximately 40km x 35km and is located south of the Tyne valley, east of the Vale of Eden and north of Stainmore Forest. The area was extensively mined in the past, probably dating as far back as Roman times. The main mining effort started in the mid-seventeenth century and, in terms of zinc-lead production, continued without interruption until the end of the nineteenth century, and at a reduced scale up until 1938. For most of this period of production, lead was the only metal of economic interest and the orefield was one of the primary lead producing areas in the world. Other mineral production including zinc, fluorite and barite commenced at the end of the nineteenth century where zinc production was primarily located in the Nenthead-Coalcleugh area. Treatment of mine waste at Nenthead between 1942 and 1943 produced 19,941 tonnes of zinc concentrate and 1,385 tonnes of lead concentrate, the only time floatation has been used within the orefield. The British Geological Survey ("BGS") has estimated the total mineral production of the orefield from 1666 to 1938 at 6 million tonnes dressed lead ore and 1 million tonnes dressed zinc ore. In addition there has been significant fluorite, barite, witherite and iron production in the area with the last mine being closed in 1999.
Minco is exploring for stratiform, replacement-style zinc and lead deposits in the unexplored, more massive limestone formations of the basal Carboniferous stratigraphy. There is significant untested potential for such mineralisation approximately 300-400m below previous, adit-accessed workings, and such deposits could be significantly larger than any previously discovered.
Within the North Pennine Orefield, there is a very strong correlation between mineralisation, especially the development of fault-localised stratiform lenses or 'flats', and the thickest and most massive limestone sequences. The bulk of the previous commercial production was derived from the massively bedded Great Limestone formation, approximately 400m above the base of the Carboniferous succession. In the main former production areas mineralisation was explored and developed by means of adits, sometimes up to 9.5km in length, driven from adjacent river valleys, principally in the 18th and 19th centuries.
The basal carbonate formations, principally the Melmerby Scar Limestone, which lie approximately 350-400m below the Great Limestone, are the thickest and most massive within the local carbonate stratigraphy. In all of the principal production areas within the orefield these deeper horizons have never been explored, although they are mineralised where they outcrop peripheral to the orefield. Minco believes it is possible that the lower formations could prove to be the principal mineralised horizons, hosting stronger and more extensive zinc-lead mineralisation than any worked previously in the overlying Great Limestone. In this, the North Pennines could be similar to the zinc-lead deposits of the Irish Midland Orefield, and other similar deposits worldwide, where the lower most massive limestone horizon tends to be the most strongly mineralised.
The initiative to explore the North Pennine Orefield has been under consideration by Minco for a number of years and was developed independently by Minco's technical team of Peter Tyler and Terence McKillen who successfully identified the potential for and led the discovery of the Pallas Green zinc-lead deposit in the southern sector of the Irish Midland Orefield. The complexity of mineral and surface rights ownership in England contributed to the long lead time in bringing the project to its present stage.
Specific exploration targets have already been identified by Minco and initial exploration drilling will be focused at three principal sites. Minco will complete approximately 4,000 metres of core drilling. The average depth of each hole will be approximately 500m.
Through a wholly-owned subsidiary, Minco has entered into agreements with a number of mineral rights and surface rights owners. The Company is in discussion with additional mineral rights and surface rights owners to add further exploration rights located in other parts of the North Pennine Orefield.