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TitreTrace elements and oxygen isotope of quartz from the Nashwaak Granite and dykes, and quartz veins related to the Sisson Brook W-Mo-Cu deposit, west-central New Brunswick
TéléchargerTéléchargement (publication entière)
AuteurZhang, W; Lentz, D R; McFarlane, C R M; Thorne, K G
SourceTGI 4 - Intrusion Related Mineralisation Project: new vectors to buried porphyry-style mineralisation; par Rogers, N (éd.); Commission géologique du Canada, Dossier public 7843, 2015 p. 475-491, (Accès ouvert)
LiensCanadian Database of Geochemical Surveys, downloadable files
LiensBanque de données de levés géochimiques du Canada, fichiers téléchargeables
ÉditeurRessources naturelles Canada
Documentdossier public
Mediaen ligne; numérique
Référence reliéeCette publication est contenue dans Rogers, N; (2015). TGI 4 - Intrusion Related Mineralisation Project: new vectors to buried porphyry-style mineralisation, Commission géologique du Canada, Dossier public 7843
Référence reliéeCette publication est reliée Lang, J R; Duncan, R; Lentz, D; Zhang, W; Bustard, A; McFarlane, C R M; Thorne, K G; (2014). Geological and structural controls on hydrothermal alteration and W-Mo mineralization in the Sisson deposit, New Brunswick, L'Association géologique du Canada-L'Association minéralogique du Canada, Réunion annuelle conjointe, Recueil des résumés vol. 37
SNRC21J/02N; 21J/03NE; 21J/06SE; 21J/07SW
Lat/Long OENS -67.1667 -66.8333 46.5000 46.1667
Sujetsanalyses des éléments en trace; géochimie des éléments en trace; éléments en trace; isotopes d'oxygène; gisements porphyriques; cuivre porphyrique; prospection minière; minéralisation; tungstène; molybdène; cuivre; or; granites; filons rocheux; Granite de Nashwaak ; géologie économique; géochimie; Paléozoïque; Dévonien; Silurien; Ordovicien
Illustrationslocation maps; photomicrographs; photographs; plots
ProgrammeInitiative géoscientifique ciblée (IGC-4), Étude des gîtes porphyriques
Diffusé2015 06 11
Résumé(disponible en anglais seulement)
The Sisson Brook W-Mo-Cu deposit, situated in west-central New Brunswick, is hosted by Cambro- Ordovician volcanic and sedimentary rocks of the Miramichi and Tetagouche groups. These rocks have been intruded by the Early Devonian Howard Peak diorite-gabbro, Nashwaak Granite, a phaneritic felsic dyke swarm, and a distinctively younger Late Devonian porphyritic felsic dyke. In order to understand the magma evolution history, the textural and geochemical characteristics of quartz phenocrysts from these felsic rocks were analyzed with the aid of SEM-cathodoluminescence (CL), laser ablation inductively coupled plasma mass spectrometry (LA ICPMS), and secondary ion mass spectrometry (SIMS).
Four intrusive granitic units in the Sisson Brook deposit area: (1) medium-grained, equigranular two-mica granite with brown biotite that is slightly altered to chlorite; (2) biotite- granite with ca. 20 % greenish brown biotite and accessory zircon, apatite, monazite, magnetite, titanite, sulfide and ilmenite; (3) biotite-granite dykes with similar mineralogical features to the biotite-granite; and (4) porphyry dykes with phenocrysts consisting of approximately 23 % plagioclase, 10 % quartz, 8 % biotite, and 7 % K-feldspar.
Quartz phenocyrsts in two-mica granite and biotite-granite plutonic phases is unzoned indicating that it formed at relatively stable magma chamber. Quartz dissolution textures in the dyke phases might be caused by cooling from 600°C to 300°C at pressure below 1 Kbar. Quartz phenocrysts in porphyry dyke samples are oscillatory-zoned. With the assumption that the activity of Ti in these magmas is 0.8 (based on the presence of ilmenite rather than rutile), Ti-In-quartz geothermometry indicates that the porphyry dykes formed at a temperature above 675°C, twomica granite and biotite-granite plutons formed at 600°C to 700°C, and the biotite-granite dykes formed at slightly below 600°C. Higher Ge/Ti ratios reflect greater degrees of magma differentiation. This ratio increases from porpyrhy dykes, two-mica granite and biotite-granite pluton phases to biotite dykes. The highest Al content of quartz measured in two-mica granite is consistent with the highest aluminium saturation index of its whole rock. The oxygen isotope of quartz is from 8-8.5 perthousand for biotite-granite, 9-10 perthousand for biotite dykes and porphyry dykes, and 10-10.5 perthousand for the two-mica granites. The later mineralization quartz veins in the dykes have oxygen isotope values between 8.5 perthousand to 9.5 perthousand, indicating the hydrothermal fluids related to the Sisson Brook deposit are dominantly magmatic fluids.