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Elmi Assadzadeh, G.*, Samson, I.M., Gagnon, J.E.Department of Earth and Environmental Sciences, University of Windsor, Windsor, Ontario, Canada, N9B 3P4*[email protected]
University of Windsor! ! ! ! thinking forward
AcknowledgementThe funding of this research is provided by NSERC.
Dr. Dave Sinclair is thanked for providing some samples used in this research.
ReferencesGagnon, J. E., Samson, I. M., Fryer, B. J., and Williams-Jones, A. E., 2003. The Canadian Mineralogist 41, 365-382.
Kooiman, G. J. A., McLeod, M. J., and Sinclair, W. D., 1986. Economic Geology 81, 1356-1373.Sinclair, W. D., Kooiman, G. J. A., and Martin, D. A., 1988. Geological Survey of Canada, 201-208.
Sinclair, W. D., Kooiman, G. J. A., Martin, D. A., and Kjarsgaard, I. M., 2006. Ore Geology Reviews 28, 123-145.
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fluorite associated with wolframite and molybdenite
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Fluorite Associations
ConclusionsThe zoning patterns in fluorite associated with Sn and W mineralization suggests a complex, dynamic fluid evolution during cassiterite and wolframite deposition, that may reflect the interplay among fluids of different character and origin. This is in contrast to the fluid environment during Mo precipitation and
subsequent stages of base metal deposition, where zonation patterns are less complex. These data also illustrate that fluorite chemistry correlates with mineralizing events and thus has possible applications in exploration for Sn-W-Mo deposit. The sum of rare element concentration can positively be used as an exploration tool to distinguish
mineralized from non-mineralized zones within a deposit. Fluorite samples from the Mount Pleasant deposit show flat REE patterns with negative Eu anomaly. This trend is in complete agreement with fluorite samples from granitic magmatism reported by Gagnon et al., 2003.
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Fig. 2. A-D) Fluorite associated with cassiterite, wolframite, molybdenite, base metals E) Barren fluorite.
Fluorite associated with base metals(fluorite + galena+ sphalerite)
Barren fluorite
Fluorite associated with molybdenite(fluorite + molybdenite)
Fluorite associated with wolframite(fluorite + wolframite + hematite)
Fluorite associated with cassiterite (fluorite + topaz + arsenopyrite + cassiterite)
Fig. 3. Cathodoluminescence images of fluorite associated with A) cassiterite, B) wolframite, C) molybdenite, and D) Barren fluorite.
Cathodoluminescence
Laser Ablation ICPMS
Our results also show that dark CL zones have significantly higher REE content than bright CL zones (Fig. 8).
The Trace Element Chemistry and Cathodoluminescence Characteristics of Fluorite in the Mount Pleasant Sn-W-Mo Deposits
Laser-ablation ICPMS analyses of various fluorite types show that fluorite from the FTZ has significantly higher W/Sn ratios than fluorite in the NZ (Fig. 4).
Fig. 5. illustrates the chondrite-normalized concentrations of rare earth elements (REE) for different fluorite types. Our data show that all fluorite types have flat REE patterns with most crystals having negative Eu anomalies; the exception is fluorite associated with base-metal sulphides, which has flat or positive Eu anomalies. Our data is consistent with fluorite chemistry from other granite-related mineralization (Gagnon et. al, 2003). Rare earth element concentrations are up to several orders of magnitude higher in fluorite associated with cassiterite, wolframite, and molybdenite than in barren or base-metal associated fluorite (Fig. 6).
Fig. 4. W/Sn ratio of various fluorite types.
Fig. 6. Chondrite-normalized REE plots for fluorite associated with A) cassiterite B) wolframite C) molybdenite, D) base metals, D) barren fluorite, and E)
wolframite+molybdenite.
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Figure 7. shows that the concentration of REE are generally higher in the FTZ relative to the NZ. The only exception is Eu with concentrations that are lower in FTZ relative to the NZ (Fig.6).
Fig. 7. the concentration of REE for the NZ and the FTZ. The diagram shows that except for Eu, the concentration of all REE are significantly higher in the FTZ.
In addition, REE concentrations are significantly higher for fluorite that is associated with cassiterite, wolframite, molybdenite, and base metals relative to those of barren fluorite veins (Fig. 5).
Fig. 5. Plot of Sum REE for various fluorite types show that barren fluorite has significantly lower REE content.
Fig. 8. Chondrite-normalized REE plot for bright CL (core), dark CL (middle zone), and dark CL (rim) in fluorite associated with cassiterite. Bright CL zone at the core has the lowest REE content.
Core
Middle zoneRim
IntroductionThe focus of this research is to understand the compositional variation of fluorite crystals within an individual deposit. Specifically, the trace element composition of barren fluorite and fluorite that is associated with various styles of mineralization were determined using LA-ICPMS to assess differences between the chemistry of various types of fluorite crystals, and if such differences can be used as an exploration tool to assess mineralizing potential.
Study AreaThe Mount Pleasant Sn (-W-Mo) deposit comprises two hydrothermal breccia pipes and mineralized granite apophyses, namely, the Fire Tower Zone (FTZ) and the North Zone (NZ) that are located in approximately 1 km apart (Fig. 1). The FTZ contains a significant W-Mo with minor Sn mineralization and the NZ hosts several major Sn deposits: Endozone (EZ), Contact Crest (CC), Contact Flank (CF), and DeepTin Zone (DTZ), as well as minor W-Mo mineralization (Kooiman et al., 1986; Sinclair et al., 1988). Ultimately, we are interested in knowing if these differences reflect fluid metal concentrations, and if these are reflected in mineral chemistry.
Fig. 1. Cross-section through FTZ and the NZ at Mount Pleasant (Sinclair et al., 2006).
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