NI 43-101 Technical report, Surface diamond drilling ... - Iamgold

R a r e E a r t h E l e m e n t E x p l o r a t i o n P r o g r a m M a r c h - 2 0 1 3
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9.2.1.4.4 Conclusion of the petro-mineralogical study of REE Zone
Petrographic and mineralogical highlights are based over historical works leaded by Fortin
(1977), Gauthier (1979) and Fournier (1993). Additional drilling of the REE Zone has been
realized recently (2011 and 2012) by IAMGOLD-Niobec. Thus 61 drill holes, totaling
37,649 m of new data, confirmed and update, particularly at depth, the previous observations.
In 2012, IAMGOLD and UQAC (Université du Québec à Chicoutimi) collaborated in a new
petrographic, mineralogical and geochemical study. A master project, realised by Alexandre
Neron, Geo. Stag. and supervised by Paul Bédard, Ing. Ph.D. will focus on the REE zone and
the new drilling datas.
The observation, at a macroscopic scale, of some of the core of these recent drill holes
confirm all the macroscopic petrographic data mentioned above with additional and
complementary information, thus:
• These breccia correspond to hydrothermal breccia related to igneous activity, attested
by the multiple hydraulic breccia structures;
• Presence of multiple breccia phases (brecciation of breccia);
• The REE zone is constituted by mainly ferrodolomitite breccia with the presence
locally of, a mineralized or not, calcitite breccia facies;
• The breccia zone shows the existence of numerous clasts of syenite highly altered
corresponding probably to xenoliths;
• Presence of at least two mineralized phases expressed by the presence of lanthanides
in the carbonates elements of the breccia (impregnation) and mainly in the matrix of
this breccia;
• Presence of at least a mineralized alteration front affecting all the core breccia
(dolomitic and calcitic) testified by the existence of small barren zones of the different
brecciated facies or small patches of different sizes in the mineralized zones.
These observations confirm the existence of multiple stages of igneous activity and a
metasomatic replacement characteristic of the carbonatite complexes.
Based on petrographic observations, the paragenesis of REE Zone can be subdivided into
four stages (Fournier, 1993):
• The first consisted of the crystallization of a dolomite low in Nb and REE (C2),
• This was followed by brecciation (C1) and deposition of synchisite and possibly
parisite, monazite and thorite. Ankerite, ferroan dolomite, hematite and chlorite were
also introduced in this stage,
• The next stage consisted of the formation of veinlets of barite, fluorite and calcite,
• The last event was the meteoric alteration which caused hematization.
This model is in accordance with the chronology of the whole carbonatite complex buildup,
advanced by Fortin in 1977:
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