| Titre | Recognizing tourmaline in mineralized porphyry copper systems: textures and major-element chemistry |
| |
| Auteur | Beckett-Brown, C E ; McDonald, A M; McClenaghan, M B |
| Source | The Canadian Journal of Mineralogy and Petrology vol. 61, issue 1, 2023 p. 3-29, https://doi.org/10.3749/2200011  Accès ouvert |
| Image |  |
| Année | 2023 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20220492 |
| Éditeur | Association minéralogique du Canada |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.3749/2200011 |
| Media | papier; numérique; en ligne |
| Formats | pdf; html |
| Province | Canada; Colombie-Britannique; Alberta; Saskatchewan; Manitoba; Ontario; Québec; Nouveau-Brunswick; Nouvelle-Écosse; Île-du-Prince-Édouard; Terre-Neuve-et-Labrador; Territoires du Nord-Ouest; Yukon;
Nunavut |
| SNRC | 1; 2; 3; 10; 11; 12; 13; 14; 15; 16; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 52; 53; 54; 55; 56; 57; 58; 59; 62; 63; 64; 65;
66; 67; 68; 69; 72; 73; 74; 75; 76; 77; 78; 79; 82; 83; 84; 85; 86; 87; 88; 89; 92; 93; 94; 95; 96; 97; 98; 99; 102; 103; 104; 105; 106; 107; 114O; 114P; 115; 116; 117; 120; 340; 560 |
| Lat/Long OENS | -180.0000 180.0000 90.0000 -90.0000 |
| Lat/Long OENS | -141.0000 -50.0000 90.0000 41.7500 |
| Sujets | tourmaline; cuivre; gisements porphyriques; cuivre porphyrique; exploration; Sciences et technologie; minéralogie; minéraux métalliques; Nature et environnement |
| Illustrations | cartes de localisation; photographies; tableaux; diagrammes; photomicrographies |
| Programme | Initiative géoscientifique ciblée (IGC-5) Systèmes minéralisés intrusions/porphyriques - processus porphyriques - minéraux marqueurs |
| Diffusé | 2023 03 10 |
| Résumé | (disponible en anglais seulement)
Samples of tourmaline supergroup minerals (TSM) from seven mineralized porphyry systems (Cu, ±Au, ±Mo) including Casino (Yukon Territory, Canada), Coxheath
(Nova Scotia, Canada), Donoso Breccia-Los Bronces (Chile), Highland Valley Copper (British Columbia, Canada), New Afton (British Columbia, Canada), Schaft Creek (British Columbia, Canada), and Woodjam (British Columbia, Canada) were examined at a
variety of scales to evaluate their relationships with mineralization. Data from paragenetic observations show that TSM are generally an early hydrothermal mineral that predates both mineralization and alteration (e.g., overgrown and crosscut by). In
general, TSM occur as sub- to euhedral crystals that are black in hand sample and can be found in a variety of mineralized settings (including breccias, veins, and disseminations) and alteration assemblages (including potassic, sodic-calcic, phyllic,
propylitic, and argillic). As TSM are resilient and occur throughout a given porphyry system they are comprehensive recorders of the type and extent of various geochemical processes that exist during the complex genesis of these systems. Data from
BSE imaging shows two primary zonation types, concentric, and sector. These are interpreted to reflect conditions of rapid crystallization and disequilibrium. Results from SEM-EDS analyses show that most TSM are dravite (~80 % of grains), with the
remainder being primarily classified as schorl. Porphyry TSM exhibits remarkably consistent ~2.0 apfu Mg values (range: 0.69 - 2.89) with the majority of TSM plotting along the oxy-dravite - povondraite trend, reflecting the predominance of the
Al3+?Fe3+ substitution at constant Mg values. This pattern starts from the povondraite side (reflecting the oxidizing nature of early porphyry mineralizing fluids) and trends towards oxy-dravite as a porphyry system evolves, a feature that can, in
turn, be interpreted to reflect relative emplacement depths. In mineralized porphyry systems, TSM exhibit remarkably similar physical and chemical characteristics among the systems examined suggesting the source and geological processes must be
extraordinarily similar. Unfortunately, these characteristics are not solely unique to porphyry systems and such observations should be integrated with additional data such as trace-element mineral chemistry to effectively discriminate TSM that have
formed in porphyry systems. |
| Sommaire | (Résumé en langage clair et simple, non publié)
L'exploration des gisements minéraux devient de plus en plus difficile. Ce manuscrit examine un minéral relativement commun (la tourmaline) dans
des gisements de cuivre à faible teneur et à fort tonnage (appelés gisements de porphyre). La tourmaline dans les systèmes porphyriques présente des caractéristiques uniques qui aident à la distinguer de celle qui se forme dans des environnements qui
ne contiennent pas de minerai de cuivre. Ce manuscrit décrit les observations de la tourmaline à partir de sept systèmes de porphyre pour créer une base de référence à laquelle les futurs chercheurs pourront se comparer. L'objectif final est de créer
une méthode par laquelle les propriétés de la tourmaline (caractéristiques texturales et chimiques) peuvent être utilisées pour aider à trouver de nouveaux gisements minéraux. |
| GEOSCAN ID | 331322 |
|
|