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Mineralogy of the Matagami and Chibougamau vanadium deposits, Abitibi, Quebec, Canada M.F. Taner, T.S. Ercit and R.A. Gault Canadian Museum of Nature PO Box 3443, Stn. "D" Ottawa, Ontario, Canada Kl P 6P4
[email protected]
ABSTRACT Vanadium mineralization occurs in oxide-rich horizons within the layered gabbro zones of the upper parts of the Bell River Complex, Matagami, Quebec and the Lac Dore Complex, Chibougamau, Quebec. The main oxide minerals are ilmenite and titanian magnetite, containing 20 to 70% of volume and the ratio of titanian magnetite to ilmenite is relatively constant, ranging from about 1: 1 to 2: 1. Their sizes are less than 5 µm to greater than 1-2 mm, occurring as coarse- to medium-grained subhedral crystals intergrown with cumulate silicate minerals (plagioclase, pyroxene, etc.). The ilmenite grains are mineralogically and compositionally homogeneous and have low V contents (average 0.18% equivalent V 20 5). In contrast, the titanian magnetite grains are inhomogeneous, consisting of trellisworks of ilmenite lamellae in Ti-poor, V-rich magnetite (less than 2 wt. % Ti02, and 1.41% equiv. V20 5 (in average). Thus, the magnetite is the principal ore mineral of vanadium; it hosts vanadium in the form of y 3+, not V 5+, as is commonly and erroneously reported.
Vanadium-Geology, Processing & Applications, COM 2002 Edited by M.F. Taner, P.A. Riveros, J.E. Dutrizac, M. Gattrell and L. Perron
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VANADIUM-G EOLOGY , PROCESSING AND APPLICATIONS
INTRODUCTION Vanadium mineralization typically occurs in oxide-rich horizons within the upper parts of layered complexes such as the Bushveld (Willemse, 1969; Von Gruenewaldt et al., l 985a and b; Reynolds, 1985). The distribution and geological relationships of these oxide-rich layers clearly indicate that they are magmatic ore deposits and that their genesis is directly related to processes that were operating during the late stages of fractional crystallization. Although there is a substantial potential for vanadium in Canada (cf. Rose, 1973), there is currently no vanadium production. However, McKenzie Bay Resources International Ltd. delivered a feasibility study at April 2002 for development of the Lac Dore vanadium deposit, Chibougamau, Quebec (Allard, 2002; Girard & Allard, 1998). Most of the vanadium deposits in Canada are associated with: ( 1) layered mafic intrusions, such as the Lac Dore Complex at Chibougamau, Quebec (Allard, 1976), the Bell River Complex at Matagami, Quebec (Taner & Allard, 1998; Taner et al., 1998); (2) Anorthosite complexes, such as the Sept Iles complex, Quebec (Cimon, 1998) and (3) anorthosite complexes, such as the Pipestone Lake Complex, Manitoba (Jobin-Bevans et al., 1997); (4) there also is a substantial vanadium potential in the Athabascan tar sands, Alberta. The present report summarizes our findings on the geology and the mineralogy of the vanadium deposits of the Bell River and the Lac Dore Complexes, Abitibi, Quebec.
THE BELL RIVER COMPLEX, MATAGAMI MINING DISTRICT
The Bell River Complex (Figure 1) is a large, layered intrusion of Archean age in the Matagami mining district. It consists of eastern and western lobes separated by the Olga granodioritic pluton (Sharp 1968; Scott, 1980; Maier et al., 1996). Although the complex played an important role as a heat source for the mineralization of a number of massive sulfide deposits in the Matagami mining district (Sharp 1968; Beaudry & Gaucher, 1986; MacLean, 1984; Piche et al. , 1993), it is poorly documented compared to similar layered intrusions in the Abitibi belt, such as the Lac Dore Complex in the Chibougamau area (Allard, 1976 and 2002). The Bell River Complex has been divided into three main zones (Figure 2): (1) a basal anorthosite zone (Main Zone), (2) a layered gabbro zone (Layered Zone), and (3) a zone consisting of apophyses and subsidiary intrusions (Granophyre/Border Zone). The basal anorthosite zone lacks a defined stratigraphy. The layered gabbro zone consists of distinctly layered Fe-Ti-oxide-rich gabbro, ± leucogabbro, minor anorthosite and pyroxenite. Vanadium mineralization within the Bell River Complex occurs within Fe-Ti-oxide-rich horizons (Figure 3A) in the layered ferro gab bro zone of the upper part of the Complex (Figure 2). This horizon is well defined on the ground and in aeromagnetic survey maps by its high magnetic susceptibility.
VANADIUM-GEOLOGY , PROC ESSING AND APPLICATIONS
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Figure 1 - Simplified Geological Map of the Matagami-Chibougamau Area, the Northern Part of the Abitibi Greenstone Belt, Quebec (Modified from MacLean, 1984)
LAC DORE COMPLEX, CHIBOUGAMAU MINING DISTRICT
The Lac Dore Complex (Allard, 1976; Girard & Allard, 1998; Allard, 2002) is located about 250 km east of Matagami (Figure 1). According to Allard (1976), the Lac Dore Complex is a Bushveld-type layered complex, folded into a large anticline and metamorphosed to the greenschist facies like the enclosing volcanic rocks, with which it is coeval and comagmatic. From bottom to top (Figure 2), the Complex has been divided into the following zones: Anorthosite Zone (Main Zone), Layered Zone, and Upper Border Zone (including Soda-granophyre and Ferrodiorite Zones). The vanadium mineralization in the Lac Dore Complex (Allard, 1976) is contained in the lower-most part of the Layered Zone (Figure 2) in Rinfret and Lemoine Townships and in the Cache Lake - David Lake area. The vanadium horizon consists .of rhythmically layered units (50 to 200 meter-thick layered zones) rich in ferroaugite, magnetite and ilmenite, intercalated with layers of leucogabbro. The Fe-Ti oxides at Lac Dore (Figure 3B) are heterogeneously and rhythmically distributed, with Fe-Ti-oxide-rich horizons intercalated with oxide-free horizons. Total evaluated resources estimated by McKenzie Bay Resources Ltd. (Girard & Allard, 1998) are about 100 million tonnes of ore with a grade of 0.49% V 20 5, including 32.2 million tonnes of measured resources with a tenor of 0.65% V 20s. The concentrated ore (vanadian magnetite) contains between 1.4% and 1.6% V20s.
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VANADIUM-GEOLOGY, PROCESSING AND APPLICATIONS
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