NI43-101Pre-Feasibility Study Report - page 125

Rare Element Resources
Bear Lodge Project
Canadian NI 43-101 Technical Report
October 9
, 2014
10135-200-46 - Rev. 0
Most of the rock units within the project area are affected by widespread potassic
alteration and have a thick near-surface oxidized zone. Recognizable hydrothermal
alteration includes pervasive fenitization (alkali-ferric iron metasomatism), K-feldspar-
pyrite alteration, minor silicification, and localized argillic alteration, along with
superimposed oxidation and surface weathering.
Geological events that are interpreted in the core of the complex include multiple
intrusions of dominantly porphyritic phonolite and trachyte, multiple brecciation
events, a primary diatreme event that hosts carbonatite magmatism, alkali-ferric iron
metasomatism (fenitization), hydrothermal alteration, REE and gold mineralization,
and supergene oxidation. Pre-intrusion, syn-intrusion, and post-intrusion faulting and
deformation disrupt the geology, although displacements appear to be relatively
7.5 Bear Lodge Deposit Alteration and REE Mineralization
REE mineralization in the Bear Lodge deposit is contained primarily within dikes,
veins, and stockwork of carbonatite, variably oxidized and leached carbonatite
(transitional and oxide-carbonate), and FMR. The latter two types of mineralization
represent progressive degrees of hydrothermal and supergene alteration of the
carbonatite that generally decrease with increasing depth. The FMR dikes and veins
are typically black to rusty brown in color. Many are friable, and drill recoveries are
often poor. However, some of the FMR bodies were subject to late silicification and
may be highly competent. REE grades tend to be higher in the FMR bodies than in
the corresponding carbonatite and can reach more than 20% TREO. The FMR bodies
and mineralization style tend to persist to depths of 500 feet (152 m) or more beneath
the surface.
Within the overall deposit, REE mineralization is concentrated in three main resource
areas, described in the next section (Chapter 8.0). These include: Bull Hill (formerly
known as Bull Hill Southwest, and including Bull Hill West), Bull Hill Northwest, and
the Whitetail Ridge resource areas. The greatest concentration of REE-mineralized
bodies occurs in NW-trending dike swarms and stockworks in the Bull Hill resource
area. Overall, the REE mineralization extends for more than 1800 meters along the
northwesterly trend (Figure 7.3). Individual dikes can reach 80 feet in width (24.4m).
The REE mineralization is open at depth, based on existing drilling, but the REE
mineralization types are zoned with depth. The generalized vertical distribution of
REE mineralization types in the Bull Hill and Whitetail resource area is shown
schematically in Table 7.2, with descriptions following.
1...,115,116,117,118,119,120,121,122,123,124 126,127,128,129,130,131,132,133,134,135,...587
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