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February 02, 2005
McLennan Property: AntOro Announces The Results of its Diamond Exploration Reconnaissance Survey
Montreal, February 2nd 2005 - AntOro Resources Inc. is pleased to announce the results of its reconnaissance survey targeting the glacial sediments on the McLennan property, located in the heart of the Le Tac Kimberlite field. The property, located 15 kilometre south-east of Desmaraisville (Quebec) within the Benoist and Le Tac townships, counts 40 map-designated claims (CDC’s) for a total area of 2,241.86 hectares.
The Reconnaissance Survey
The reconnaissance survey was initiated following the acquisition of these claims (See the April 2nd, 2004 news release) and specifically targeted the quaternary tills in order to extract the heavy minerals fraction that may contain Kimberlite Indicator Minerals (KIM’s). A total of 68 till samples were collected down ice-flow from magnetic targets identified from the examination of the publicly-available magnetic airborne surveys. Following the collection of the samples, the Company sent them to IOS Services Géoscientifiques of Saguenay (Québec) for separation and heavy minerals fractions analysis and the subsequent microprobe work.
AntOro is particularly pleased to announce that 603 Indicator minerals have been extracted from the 68 samples submitted to the laboratory.
Pyropes (using Dawson et Stephens, 1975)
Using this classification, 23 mantle-derived garnets were recovered: one (1) Harzburgitic or “G10” garnet, four (4) Lherzolitic or “G9” garnets, thirteen (13) catazonal garnets “G5”, four (4) eclogitic garnets or “G3” and one (1) low-chromium megacryst or “G1”. By taking the quantitative
(microprobe) results for the Lherzolitic and Harzburgitic garnets and plotting them on a Cr2O3 vs. CaO (in weight %) graph, the Harzburgitic garnet plots into the exclusive diamond-stability pyrope field, deeming it a diamond–inclusion (DI) “G10”. This significant result could infer that the source of this pyrope fits in the diamond window. Furthermore, the chemistry of the Lherzolitic garnets indicate a catazonal origin and are similar to other pyropes found in the immediate region. The four Eclogitic (G3) garnets demonstrate a particular chemistry classifying them into the « Type B » eclogitic garnets that usually co-exists with diamonds.
The company wishes to remind the reader that a similar Harzburgitic (G10) garnet was uncovered by the Fonds de prospection minière Jamesien during an esker-sampling survey in the region as described in their November 20th 2004 press release.
Diopsides
Four (4) uncovered diopside grains deemed as being mantle-derived were plotted on the Kosmochlor-Jadeite axis which discriminates these pyroxene minerals in diamond-exploration chemistry. Two (2) of these diopside grains gave geothermic calculations results showing that the chemical equilibrium into the diamond field for an undisturbed geothermal gradient with surface heat-flux values of 40 mW/m2, indicating a diamond-bearing kimberlitic source. These minerals are highly susceptible to mechanical weathering conditions predominant in this glacial context. Their presence in the samples implies that the parent rock is close to the sampling site.
Picroilmenites
A total of 324 picroilmenite grains were recovered from the samples. This high count is a telltale sign of the presence of kimberlite or ultramafic lamprophyres. At least 50% of these picroilmenites had significant chromium enrichment (between 5% and 14% Cr2O3) and showed similar compositions to the varieties found in diamondiferous kimberlites.
Chromites
On the 142 extracted chromite grains and submitted to microprobe analysis, 29 can be plotted as a coherent population into the diamondiferous kimberlites (HZ Chromites), Diamond Inclusion Chromites (DI Chromites) and diamondiferous peridotitic xenoliths (DG Chromites) definition fields. Of these 29 chromite grains, 7 plot directly within the DI- and DG-Chromites. Another significant result is the presence of 16 zinc-enriched chromite grains; AntOro would like to point out that these Zinc-enriched chromite grains are similar to those found in the Lac de Gras (Nunavut) and Wawa (Ontario) diamond-exploration camps.
Ti-Andradites
22 Titanium-rich andradites were extracted and analyzed. These black garnets are commonly found in the magmatic phase of ultramafic lamprophyres and were found in a Le Tac field kimberlitoïd rock and also in the Selco field in Northern Ontario. Ti-Andradites were also found in the Renard pipes in the Otish mountains of Quebec.
Conclusion
The presence of an Harzburgitic garnet plotting in the diamond window together with five (5) low-Cr pyropes and Type-B Eclogitic garnets (E-Garnets) suggest the presence of a diamond-fertile source-rock. The Kosmochlor diopsides demonstrate that diamond crystal growth stability conditions were attained and the parent rock is in the near vicinity. The presence of important concentrations of picroilmenites in the samples indicates the presence of kimberlites or lamprophyres in the region and their distinctive chemical signature reveals diamond-conservation conditions. Finally, the KIM Chromites present chemical compositions of similar minerals found as inclusions in diamond crystals.
Future Work
The Company wishes to follow-up on these excellent results and pursue the diamond exploration activities in the region with an orientation survey in order to find the source of these Kimberlite Indicator Minerals. The company is also considering the realisation of a high-density airborne magnetometric survey.
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