Mineral Reconnaissance summaries data releases 1-23
These comprise data collected during an MRP investigation accompanied by a brief outline of the work carried out. They were often produced to allow the release of data cheaply or quickly and in some cases were superceded by MRP Reports. Unlike MRP reports, the earlier releases contain little or no interpretation or assessment of the data presented. Later releases (14 onwards) contain more information and are written in a similar style to reports. Brief summaries of the contents of data releases are given below.
Releases 1-7: These were largely superseded by later work and reports.
Release No. 8: Data arising from drilling investigations in the Loch Borralan intrusion, Sutherland
M H Shaw and 5 others (1992)
Release No. 9: Data arising from investigations of the Knock intrusion at Claymires, Aberdeenshire
M T Styles and 8 others (1992)
Data arising from detailed geophysical surveys followed by the drilling of two IP anomalies on the eastern margin of this intrusion are presented. The work, based on a model of platinum-bearing shear zone-hosted copper-nickel-sulphide mineralisation, did not identify any significant sulphide mineralisation or attendant precious-metal enrichments.
Release No. 10: Data arising from investigations into the distribution of platinum-group elements, South Harris, Isle of Lewis, Scotland
M H Shaw, A G Gunn and J R Mendum (1993)
Geochemical (stream sediment, panned stream sediment and surface rock sample) data are presented. The data show minor palladium enrichment (maximum 210 ppb) in ultramafic rocks within the Langavat Metamorphic Belt, on the eastern margin of the South Harris igneous complex, and in metasediments within the same belt. Some palladium-enriched rocks also show minor enrichment in platinum and gold.
Release No. 11: Rare-earth elements in alkaline intrusions, north-west Scotland
M H Shaw and A G Gunn (1993)
Geochemical data on rare-earth element (La, Ce and Y) concentrations in rocks from the Loch Borralan, Loch Ailsh and Ben Loyal alkaline intrusive complexes are presented. In drill core from the Loch Borralan Complex the analyses indicate only localised minor concentrations in excess of 1000 ppm La+Ce. At Loch Ailsh, localised minor enrichment of rare-earth-elements occurs in syenites and pyroxenites near the south-east margin of the complex. Data from a limited programme of sampling at Ben Loyal resulted in the discovery of veins rich in rare-earth elements (maxima 5667 ppm La and 19785 ppm Ce) in syenites.
Release No. 12: Mineral investigations in the Scardroy area, Highland Region, Scotland
J S Coats, M H Shaw and R T Smith (1993)
Data arising from a reconnaissance geochemical survey in the Scardroy area of north-west Scotland are presented. Stream-sediment and panned-concentrate results indicate that the majority of gold anomalies in the area are associated with the Strathconon Fault. The survey also led to the discovery of strongly deformed chalcopyrite-bearing pyrrhotite bodies up to four metres thick in Lewisian amphibolite.
Release No. 13: Exploration for gold in Central Wales
M J Brown (1993)
The results of a panned-concentrate drainage survey across selected areas of Central Wales are contained in this release. The objective of the survey was to search for evidence of mesothermal 'slate-belt type' gold mineralisation similar to that worked at Ogofau, near Pumpsaint. Two anomalous areas were identified: the Rhiwnant Dome near Rhayader and a catchment close to the Ogofau mine at Caeo. Both areas have structural and other geological features in common with the site of the Ogofau mine.
Release No. 14: Geochemical surveys for gold in the Berwyn Hills
R T Smith (1993)
The results of a geochemical survey centred on the Afon Trystion in the western Berwyn Hills are reported. The presence of coarse gold in the Afon Trystion, first reported by an earlier regional-scale survey was confirmed, but its source was not identified. Only minor indications of mineralisation were found in the Lower Palaeozoic clastic sedimentary rocks that form this area.
Release No. 15: An appraisal of the gold potential of mine dumps in the North Molton area, North Devon
D G Cameron and D J Bland (1994)
Values of gold are reported for twelve samples taken from dump material at the old Bampfylde Fe-Cu Mine. These values suggest that there may be sufficient gold present to support a small scale commercial extraction enterprise. Samples from tips at six other iron ± copper mines in the area were found not to be auriferous.
Release No. 16: Exploration for stratabound mineralisation around Chillaton, Devon
R C Leake, K Smith and K E Rollin (1994)
Results of reconnaissance overburden sampling and geophysical surveys over an area of Lower Carboniferous sediments, mafic volcanics and basic intrusions with associated manganese mineralisation are presented. Drilling showed the source of prominent conductivity, chargeability and, SP anomalies, coincident with a positive gravity anomaly, to be black, pyrite-rich shales. Minor manganese mineralisation was intersected in the envelopes of doleritic intrusions and weak base-metal enrichments were recorded locally in the volcanic and sedimentary succession.
Release No. 17: Regional appraisal of potential for stratabound base-metal mineralisation in the Solway Basin
T B Colman and 6 others (1995)
The basin, which is up to 7km thick, developed due to north-south extension with major fault-controlled subsidence during the Courceyan-Holkerian (syn-extension phase), followed by more gradual post-extension regional subsidence during the later Carboniferous. It straddles the trace of the Iapetus Suture on whose extension major Irish lead-zinc deposits are located. The basinal succession is poorly exposed away from the margins where it is covered by later Permo-Trias sediments and extensive drift deposits. Minor base-metal and baryte vein and replacement mineralisation is recorded close to the northern and southern margins. Investigations of the regional geochemistry, geophysics and deep geology, together with Landsat imagery, indicated that the basin could be prospective for syn-diagenetic mineralisation of Sedex style found in Ireland adjacent to basin-controlling faults, but that the most prospective rocks in chronostratigraphic terms are likely to be at considerable depth on the southern margin. Close to the northern margin prospective areas were identified and limited follow-up investigations carried out. These are described in Data Releases 18 and 20-23.
Release No. 18: Mineral investigations in the Northumberland Trough: Part 1, Arnton Fell area, Borders, Scotland
R T Smith, A S D Walker and D J Bland (1996)
In this area, at the northern margin of the Northumberland Trough, stream sediment anomalies for barium and base-metals recorded by regional scale surveys were followed-up by panned stream sediment and deep overburden sampling and geophysical (magnetic and VLF) surveys. Strong anomalies for Cu, Pb, Zn and Ba in panned stream sediment were recorded over much of the area. Mineralogical examination of the samples revealed the presence of coarse untarnished sphalerite, more locally galena chalcopyrite and gold, and rare cinnabar and mimetite. Outcrop sampling revealed weak vein-style mineralisation and weakly disseminated galena in a sandstone unit. The small amount of deep overburden sampling undertaken revealed few high values but some coincidence of these with the Coomb Edge Fault was evident. Geophysical surveys failed to detect pronounced anomalies associated with the sub-outcropping Birenswark Lavas or the Coomb Edge Fault. It was concluded that vein-style mineralisation was the most probable source of most anomalies, and that this might include polymetallic (Cu, Au, Pb, Hg, Ba) veins associated with Lower Palaeozoic rocks, and sphalerite-baryte mineralisation in the Carboniferous cementstone succession. Most mineralisation is concealed by the extensive drift deposits.
Release No. 19: Exploration for gold in the Thornhill Basin, southern Scotland
R C Leake and D G Cameron (1996)
The presence of alluvial gold associated with Permian red beds of the Thornhill basin is reported. The gold occurs mostly in streams on the eastern side of the basin where Permian rocks are in faulted contact with the Lower Palaeozoic succession. Electron microprobe studies of the gold grains show that they are similar to those discovered in Devon (south Hams and Crediton Trough) and that the mineralised source is therefore likely to be metallogenetically similar. There is sufficient evidence to suggest that mineralised structures carrying gold occur at contacts between the Lower Palaeozoic and Permian rocks and, possibly, also in structures cutting the Permian rocks.
Release No. 20: Mineral investigations in the Northumberland Trough: Part 2, Newcastleton area, Borders, Scotland
R T Smith and A S D Walker (1996)
In this area, close to the northern margin of the Solway-Northumberland Trough, stream sediment anomalies for zinc with lesser amounts of lead, barium and copper recorded by regional scale surveys were followed up by panned stream sediment, outcrop and traverse-based deep overburden sampling. Mineralogical examination of the panned concentrates showed the anomalies to be caused by sphalerite often accompanied by variable amounts of baryte, chalcopyrite, galena pyromorphite and secondary lead minerals. Deep overburden sampling revealed base-metal anomalies in a well-defined zone close to the Bedda fault. Most anomalies are attributed to fault-controlled vein-style base-metal and baryte mineralisation, but evidence of disseminated syngenetic sphalerite-pyrite mineralisation was discovered in a carbonate-cemented sandstone unit in the Harden beds. Geophysical orientation studies indicated that magnetic surveys are useful locally for tracing faults beneath the thick overburden.
Release No. 21: Mineral investigations in the Northumberland Trough: Part 3, Ecclefechan-Waterbeck area
R T Smith and A A McMillan (1996)
In this area, at the northern margin of the Solway-Northumberland Trough, stream sediment anomalies for barium and base-metals recorded by regional scale surveys were followed up by panned stream sediment, outcrop and deep overburden sampling. Mineralogical examination of the panned concentrates indicated that the anomalies were the product of both mineralisation and contamination. Nevertheless, a substantial zone of coherent Cu-Pb-Ba enrichment over the Birenswark Volcanic Formation and a cluster of anomalies close to the Silurian-Upper Old Red Sandstone boundary were identified. Deep overburden sampling revealed base-metal anomalies presumed to be derived from concealed mineralisation in the vicinity. Gold grains, seen in panned concentrates at 13 sites, may be derived from Silurian rocks at the basin margin. Examination of the core from a previously drilled borehole (Hoddam No.2) sited close to this area revealed the presence of gypsum-anhydrite in veins, breccias and massive beds, increasing the prospectivity of the area according to some metallogenetic models.
Release No. 22: Mineral investigations in the Northumberland Trough: Part 4, the Bewcastle area
R T Smith and D J Bland (1996)
Stream sediment anomalies for zinc with lesser amounts of lead, barium and copper recorded by regional scale surveys were followed up by panned stream sediment and outcrop sampling. In the lower parts of the area streams are contaminated giving rise to anomalies from both natural and anthropogenic sources. The large zinc anomalies are caused by the presence of coarse sphalerite and coarse baryte is also common. Widespread but weak vein-style sphalerite-baryte-pyrite mineralisation was found in anomalous catchments, but no stratabound mineralisation apart from pyrite was seen. Gold was panned from ten sites and appears to be associated with the presence of Permo-Carboniferous quartz dolerite dykes, but its source is uncertain.
Release No. 23: Mineral investigations in the Northumberland Trough: Part 5, the Kirkbean area south-west Scotland
R T Smith and 5 others (1996)
Drainage geochemical anomalies recorded by previous surveys in this area, close to the northern margin of the Solway-Northumberland basin, were followed-up by traverse-based soil sampling from pits, outcrop sampling and geophysical surveys (magnetic, electromagnetic and gravity). The work was designed to provide information on the geology and structure beneath the thick drift cover and outline base-metal and baryte drilling targets. Deep overburden sampling using a power auger was then carried out in part of the area where the earlier work suggested the presence of sub-surface mineralisation coincident with intersecting faults. The results suggested that mineralised (vein-style) structures carrying baryte and/or base-metals may extend over a strike length of 2.5km or more in this area. Both base-metal and baryte mineralisation is exposed at surface in a few places, but most of the area is covered by thick drift deposits. Much of the mineralisation may comprise small epigenetic occurrences but there are good indications of a relatively large steeply-dipping baryte-bearing vein structure and the possibility of more substantial stratabound or breccia infill deposits.
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