| Title | Scheelite geochemical signatures and potential for fingerprinting ore deposits |
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| Licence | Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences. |
| Author | Poulin, R S; McDonald, A M; Kontak, D J; McClenaghan, M B |
| Source | TGI 4 - Intrusion Related Mineralisation Project: new vectors to buried porphyry-style mineralisation; by Rogers, N (ed.); Geological Survey of Canada, Open File 7843, 2015 p. 317-326, https://doi.org/10.4095/296473  Open Access |
| Links | Canadian Database of Geochemical Surveys, downloadable
files
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| Links | Banque de données de levés géochimiques du Canada,
fichiers téléchargeables
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| Image |  |
| Year | 2015 |
| Publisher | Natural Resources Canada |
| Document | open file |
| Lang. | English |
| Media | on-line; digital |
| Related | This publication is contained in TGI 4 - Intrusion Related
Mineralisation Project: new vectors to buried porphyry-style mineralisation |
| Related | This publication is related to Scheelite geochemical
signatures and potential for fingerprinting ore deposits |
| File format | pdf |
| Subjects | geochemistry; economic geology; scheelite; mineral deposits; arsenic; molybdenum; rare earths geochemistry; indicator elements |
| Illustrations | photographs; plots |
| Program | Targeted Geoscience Initiative (TGI-4) Intrusion/Porphyry Ore Systems |
| Released | 2015 06 11; 2023 03 17 |
| Abstract | Scheelite (CaWO4) is a common accessory mineral found in a variety of geologically diverse ore-deposit settings, including vein/stockwork, skarn, porphyry, epithermal and strata-bound. As part of the
Geological Survey of Canada's (GSC) Targeted Geoscience Initiative (TGI 4) program, the project reported on here was developed to investigate the potential for discriminating scheelite originating from different ore-deposit types. The study
investigated whether crystal-chemical features of scheelite, such as cathodoluminescence (CL), trace-element chemistry, and isotopic signature (O), could be used independently or together as deposit-type discriminators, thereby assessing the
feasibility of using scheelite for provenance studies in regional till-sampling programs. Here we report on the geochemical data obtained using the LA ICP-MS method on scheelite to see if it could be used to geochemically fingerprint its environment
of formation. The samples used come from the granite-related, world-class Sisson W-Mo porphyry-type deposit, NB, along with forty-one scheelite samples from a range of deposit types that constituted the suite used in the broader crystal-chemical
study. The protocol used was twofold: (1) collect data using line traverses and integrate the data over intervals showing uniform chemistry; and (2) generate element maps for a select few scheelite grains which displayed complex zoning patterns
revealed through CL imaging. Despite using an extensive element list (e.g., LILEs, alkalies, transition metals, HFSEs), only Mo, As and the REEs, which follow crystal growth patterns, showed significant levels of elemental enrichment (i.e., > 1.0
ppm). The correlation of As and Mo indicate only a small intra-deposit variance, but the large inter-deposit variation offers the potential to use this element pair to discriminate deposit types. The results for the REEs indicate: (1) a lack of
apparent correlation between REEs and the type of CL observed despite previous suggestions to the contrary; (2) considerable variation in the ?REEs amongst the sample suite used; (3) most samples are dominated by a single chondrite-normalized (CN)
pattern, but rarely a second pattern is present; although the type of CN REE patterns vary (e.g., convex MREE, LREE enrichment), there is a similarity among deposit types; and 5) both positive and negative Eu anomalies are observed. These initial
results suggest that the minor and trace-element chemistry of scheelite along with CL imaging, may offer the potential to discriminate and identify deposit types based on its geochemical fingerprinting. |
| Summary | (Plain Language Summary, not published)
The Targeted Geoscience Initiative (TGI-4) is a collaborative federal geoscience program that provides industry with the next generation of geoscience
knowledge and innovative techniques to better detect buried mineral deposits, thereby reducing some of the risks of exploration. This volume summarises research activities completed under the TGI 4 Intrusion Related Mineralisation Project that
focused on porphyry-style ore systems related to the Cu- and Cu-Mo deposits of South-Central British Columbia and the Sn-W-Mo-In deposits in New Brunswick, Nova Scotia and Newfoundland. |
| GEOSCAN ID | 296473 |
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