The Touro target was an active garimpo (artisanal mine) in the 1980s and is located 17 kilometres southwest of Aurizona. The miners processed gold from quartz veins and vein stockworks hosted by altered tonalities and diorites that were mined from open pits and underground workings along the north-south trending Touro Shear Zone (TSZ). A large tailings deposit, the product of artisanal mining, extends for 1 kilometre north-south at Touro. Outcrop is limited to the walls and floors of garimpo pits. Luna conducted several exploration programs including geological mapping, rock and channel sampling, geophysical surveys, a scout reverse circulation program, and a tailings auger drill program. Seven diamond drill holes totaling 1,674 metres were drilled in Q4 2012 testing a strike length of 400 metres. All holes intersected gold mineralization and the target remains open to the North and South along strike and at depth. Significant intercepts are shown below and in Table 3.
- 57.00 metres @ 0.81 g/t Au including 26.00 metres @ 1.26 g/t Au and 1.00 metre @ 7.12 g/t Au in TOURD001 (Section 0000 )
- 24.00 metres @ 1.24 g/t Au including 2.00 meters @ 7.51 g/t Au in TOURD002 (Section 0100S)
- 85.00 metres @ 0.72 g/t Au including 8.00 meters @ 1.27 g/t Au and 5.00 meters @ 1.11 g/t Au in TOURD003 (Section 0200S)
Figure 1. Location of the Touro target, Luna Greenfields project overlain on 1VD magnetic grid (CPRM, 2008).
Surface Channel Sampling Program
Following reconnaissance geological mapping, a channel sampling program was conducted across all available outcrops at Touro. Some 461 metres of sampling (523 individual samples including QA/QC) was completed. Detailed mapping was conducted along the channels, and these data have been integrated into a preliminary geologic model. The program identified several zones of both low and high grade outcropping gold mineralization. Diamond drilling intersected the down-dip extensions of this surface mineralization. Select mineralized channel intervals are tabulated below in Table 1.
Table 1. Average gold grades from surface channel sampling of saprolite at the Touro target. Mineralized intervals are reported. Assay intervals listed are composites. A total of 461 metres of outcrop was sampled. Assay values for surface channel samples not reported here range between below detection limit (<0.05 g/t Au) to 2.19 g/t Au.
Reverse Circulation Drill Program
There is lack of outcrop at Touro due to the occurrence of extensive tailings deposits. Accordingly, a reverse circulation (?RC?) drill program was conducted to test for mineralized saprolite to a maximum depth of 30 metres beneath these deposits. This program successfully delineated a sub-cropping mineralized zone beneath the tailings to the north and south of the garimpo pits. This information assisted in the siting of diamond holes and the mapping of the TSZ. Select mineralized RC drill intercepts are tabulated below in Table 2.
Table 2. Top ten mineralized drill intercepts from the scout Touro RC drill program. Intervals are calculated as composites using a 0.30 gram/tonne Au cut-off and maximum 2 metres of internal waste. True widths to be established. Mineralized surface tailings material is not reported in the intervals.
Rock sampling was also conducted to determine the grades of individual quartz vein sets. Some 95 samples were collected during geologic mapping. Gold values range from below detection limit to 26.20 grams per tonne and 35% of samples (34 samples) assayed greater than 0.50 grams per tonne.
Diamond Drill Program
The initial seven hole diamond drill program, which totalled 1,674 metres, was designed to intersect mineralization in transition and fresh rock along the North-South trending TSZ, in addition to providing information to build a preliminary geologic model. All holes were drilled on surveyed 100 metre spaced sections towards 100o azimuth to intersect the shear zone at right angles. All holes intersected mineralization. When integrated with the RC and channel sample data, these holes define a mineralized zone (?MZ?), extending for over 400 metres strike length trending North-North/East, that remains open to the north and south (Figure 2). The maximum width of the MZ at surface is 90 metres (section 0100S). Mineralization was defined to a maximum depth of 140 metres (TOURD006, Section 0000). Significant mineralized intercepts from holes drilled across the TSZ are tabulated below in Table 3.
Figure 2. Touro target preliminary 3D geologic model showing main NNE-trending mineralized zone (red) and host tonalities (yellow) and diorites (green).
Table 3. Mineralized drill intercepts from the initial Touro exploration drill program. Intervals are calculated as composites using a 0.30 gram/tonne Au cut-off and maximum 2 metres of internal waste. True widths to be established. Mineralized surface tailings material is not reported in the intervals.
Gold mineralization at Touro is hosted in sheared tonalities and diorites of Paleoproterozoic age. The principal MZ trends North-North/East within the dextral brittle-ductile TSZ. Intensely altered tonalities constitute the dominant host unit for the wide zones of gold mineralization. Tonalite alteration consists of silicification, sericitization, carbonatization, sulfidation, and albitization, along with introduced tourmaline and intense bleaching. Pyrite is the dominant sulfide mineral and constitutes up to 3% of the rock mass. Several sub-parallel narrow mineralized zones also cut the diorite (see cross-sections). Gold is also directly associated with quartz veins and stockworks. Three distinct sets have been mapped to date. Luna recommenced drilling at Touro in January 2013 to identify additional mineralized structures and to generate data to support an initial resource estimate.
