Publication Type:Journal Article
Source:The Canadian MineralogistThe Canadian Mineralogist, Volume 54, Number 5, p.1147-1173 (2017)
Keywords:Cathodoluminescence, Laser ablation ICP-MS, mineral chemistry, Ore deposits, Scheelite
The relationship between cathodoluminescence (CL) response and chemical composition of scheelite from a variety of ore- deposit settings (e.g., orogenic Au, skarn, porphyry-related, greisens, VMS) was investigated using SEM-EDS, CL imaging, and LA-ICP-MS techniques. Our detailed study concentrates on five samples of scheelite from a range of ore-deposit settings, including orogenic Au, skarn, VMS, and greisen deposits, but draws on a yet unpublished data base of more than 39 deposits world-wide. Results indicate that the scheelite zonation patterns observed under CL can be useful in discriminating between scheelite arising from differing mineralized environments. Scheelite from orogenic Au deposits exhibits a homogenous CL response in contrast to that from proximal intrusion-related systems, such as porphyries, skarns, and greisens that show a strong oscillatory zonation, with individual zones ranging from,1 lmto.300 lm in width. Results from LA-ICP-MS analyses show significant chemical variations in scheelite with respect to Mo, Sr, As, and RREEþY. Maps generated from CL imaging and LA-ICP-MS data reveal a strong negative correlation between the intensity of the CL response in scheelite and Mo content. While enrichments of Sr, As, and RREEþY are noted, none exhibit a correlatable effect with CL response. Furthermore, the qualitative Mo andWX-ray maps produced via SEM-EDS correlate with the corresponding LA-ICP-MS maps of the scheelite grain, successively delineating the zonation patterns observed under CL. This work also demonstrates that the combination of CL and LA-ICP-MS mapping is a powerful tool in the discussion of observed CL textures, elemental relationships, mineral growth history, and paragenesis.