The Gold Plateau Properties
The Gold Plateau Project is located in southern Tanzania, approximately 150 km north of the Mozambique border. Ruby Creek's Gold Plateau Project consists of 15 properties of highly prospective gold mineralized territory. The mining and mineral rights were acquired for over $12 million in a series of business transactions.
Gold mineralization in the area was first discovered by Geological Survey of Tanzania following a country-wide geochemical surveying program in 1990's. Small scale artisanal mining activities commenced in 2002 by local miners, aimed at exploring and mining gemstone. However, a significant amount of gold was recovered from the concentrates and hence the area turned from gemstone to alluvial gold mining. The reported production from artisanal mining work by local miners was reported to average between 1.5 to 2 kilograms of gold per month, recovered from loose sands and gravels.
The Gold Plateau Project is situated at the eastern margin of the Selous Basin where Karoo and young sedimentary rock are in fault contact with low to high-grade metamorphosed rocks of Neoproterozoic age belonging to the Mozambique Belt. The Proterozoic basement rocks are bounded by Paleozoic, Mesozoic and Cenozoic basins to the east, north and west. The dominant rocks are biotite schist and gneiss, granitic gneiss, garnetiferous, amphibolite's, quartzite, pegmatite dyke and mafic sills which are unconformably overlain by palaeo-placer sand and pebble beds and recent superficial deposits. The regional structural trends that control the deposition appear to be trending at northwest and northeast.
The geology of the property is dominated by thick (up to 10 m) of transported cover consisting of palaeo-placer sand, gravel and pebble beds derived from Karoo to the west and younger sedimentary rocks. The sand horizon is massive, graded from fine to coarse grained, characterized by orange-yellow sands, well exposed at Old Matandani Prospect, and white-grey sands which cover the large part of the property. The basal conglomerate pebbles (auriferous pebbles and cobbles beds) are well rounded, well sorted, dominantly made of quartzite, quartz rocks, and other basement rocks.
The thickness of palaeo-placer sand--pebble beds and the overlaying black clays material increase toward the eastern part of Mbwemkuru River as observed at Mkilikage Prospect. This would be expected if the source of the deltaic or beach placer material is from the west. At Mkilikage Prospect, a thick layer of medium to coarse grained sandy bed (~ 2.5 m thick) resulted from modern river deposition is overlaying palaeo-placer sand-pebble beds. This sandy bed is characterized by well-developed cross bedding sedimentary structures with minimal gold content until the lower reaches.
The red-brown sands are massive with no obvious bedding. They comprise subangular quartz grains with a matrix of hematite clay. They range from <1 m up to 3 m thickness, and generally appear to be thicker upslope, particularly at the western extremity of the property, well exposed at Old Matandani workings. They have been reworked in the current river bed, with removal of the clay, to produce white friable sands that extend for up to 300 m, but generally less, up slope. These are clearly gold-bearing as they have been extensively mined by artisanals, but panning suggests that they are low grade.
The sands overlie a polymictic conglomerate sequence that comprises several clay-rich, horizontally bedded units interlayered with sandy beds. The clastsrange from pebbles through cobbles to boulders, the latter being only sporadically developed, but suggesting that there may be distinct channels in the conglomerate sequence up slope from the present river. Artisanal activity and panning indicate that the conglomerates have higher gold grades than the overlying sands. This feature would be anticipated in a delta or beach placer forming river fan.
Most of the Neoproterozoic basement rocks are exposed on the NE-SW trending ridge located in the central-eastern portion of the property with few outcrops observed in the south part, exposed on the river banks and beds. The basement geology consists of granite-gneisses, biotite gneiss, schist and quartzo-feldspathic gneiss and quartzite, which have been intruded by pegmatite veins and mafic dykes and quartz veins.
The quartzite has a bedded sugary texture. The biotite gneiss is fine grained, well bedded with biotite, feldspar and quartz. Quartz-feldspar gneiss additionally contains minor biotite and was also observed to contain some large augen like feldspar crystals. Pegmatite was generally seen to have graphic texture with very coarse grained feldspar and smaller quartz crystals, and with only biotite or chlorite as an accessory mineral. The granite-gneiss characterized by granoblastic texture and weakly developed foliation fabrics.