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The recently recognized Sanagak Lake shear zone (SLsz) is a 165 km long, southwest striking corridor of high-strain rocks that transects the southern portion of Boothia Peninsula, Nunavut. This zone records pervasive deformation ([??]) at conditions of ~0.52 GPa and ~700 [degrees]C, and localized deformation ([??]) at [greater than or equal to]0.5 GPa and 300-500 [degrees]C that preserve left lateral and right lateral senses of movement, respectively. Neocrystallized [??] titanite in a hornblende-bearing granodiorite yields an age of 1804 [+ or -] 6 Ma, interpreted to be the timing of [??]. The timing of [??] is loosely bracketed by [.sup.40]Ar/[.sup.39]Ar hornblende (1814 [+ or -] 3 Ma) and biotite (1743 [+ or -] 1 Ma) cooling ages since the deformation temperature falls between the estimated closure temperature of these minerals. Similar rock types and metamorphic conditions on either side of the shear zone rule out the SLsz as a terrane boundary. Rather, strain localization may have been triggered by thermal softening related to the emplacement of a northeast-trending belt of high-temperature granites south of the shear zone between 1840 and 1820 Ma. Deformation and metamorphism at ca. 1.81 Ga south of Boothia Peninsula and in the central Rae (Committee Bay belt) have been attributed to the Superior Province colliding with the southeastern margin of the Rae craton, such that the SLsz may too have formed in response to far-field stresses derived from this collision. The absence of ca. 1.81 Ga tectonic fabrics north of the shear zone indicates that the SLsz marks the northwestern extent of mid-crustal, Trans-Hudson related tectonometamorphism. Key words: Churchill Province, shear zone, Trans-Hudson Orogeny, titanite geochronology, thermobarometry, quartz CPO La zone de cisaillement du lac Sanagak (zcLS) récemment découverte est un couloir de roches hautement déformées d'orientation sud-ouest de 165 km de long qui traverse la partie sud de la presqu'île de Boothia (Nunavut). Cette zone conserve le registre d'une déformation répandue (DSL1) à des conditions de ~0,52 GPa et ~700[grados]C et d'une déformation localisée (DSL2) à [mayor que o igual a] 0,5 GPa et 300-500 [grados]C, préservant respectivement des sens de déplacement dextre et senestre. De la titanite DSL1 néocristallisée dans une granodiorite à hornblende donne un âge de 1804 [+ ó -] 6 Ma interprété comme étant l'âge de DSL1. L'âge de DSL2 s'établit généralement entre les âges de refroidissement [.sup.40]Ar/[.sup.39]Ar de la hornblende (1814 [+ ó -] 3 Ma) et de la biotite (1743 [+ ó -] 1 Ma), étant donné que la température de la déformation se situe entre les températures de fermeture estimées de ces deux minéraux. Des types de roches et conditions métamorphiques semblables de part et d'autre de la zone de cisaillement excluent l'interprétation de la zcLS comme étant la limite d'un terrane. La localisation de la déformation pourrait plutôt avoir été déclenchée par l'amollissement thermique associé à la mise en place d'une ceinture de granites de haute température d'orientation nord-est au sud de la zone de cisaillement entre 1840 Ma et 1820 Ma. La déformation et le métamorphisme vers 1,81 Ga au sud de la presqu'île de Boothia et dans le centre du craton de Rae (ceinture de la baie Comité) ont été attribués à la collision de la province du Supérieur avec la marge sud-est du craton de Rae, la zcLS pouvant également s'être formée en réponse à des contraintes de champ lointain découlant de cette collision. L'absence de fabriques tectoniques d'environ 1,81 Ga au nord de la zcLS indique que cette dernière marque la limite nord-ouest du tectonométamorphisme médio-crustal associé à l'orogène trans-hudsonien. [Traduit par la Rédaction] Mots-clés : province de Churchill, zone de cisaillement, orogène trans-hudsonien, géochronologie sur titanite, thermobarométrie, OCP du quartz, Introduction The Churchill Province is one of the largest and most complex pieces of Archean crust on Earth (e.g., Hoffman 1988; Davis et al. 2006; Berman 2010). The province has [...]

New U-Pb zircon ages are reported for granulite facies crustal xenoliths brought to the surface by mafic lavas in the Snake River Plain. All samples yield Meso-to-Neoarchean ages (2.4–3.6 Ga) that significantly expand the known extent of the Archean Wyoming Craton at least as far west as the west-central Snake River Plain. Most zircon populations indicate multiple growth episodes with complexity increasing eastward, but they bear no record of major Phanerozoic magmatic episodes in the region. To extrapolate this work further west to the inferred craton boundary, zircons from southwestern Idaho batholith granodiorites were also analyzed. Although most batholith zircons record Cretaceous formation ages, all samples have zircons with inherited cores—with some recording Proterozoic ages (approaching 2 Ga). These data enhance our perspectives regarding lithosphere architecture beneath southern Idaho and adjacent areas and its possible influence on Cenozoic magmatism associated with the Snake River Plain–Yellowstone "melting anomaly". [ABSTRACT FROM AUTHOR]

Abstract: The Omineca Belt between Nelson and Creston in southeastern British Columbia was affected by overlapping pulses of Mesozoic magmatism, metamorphism, and deformation. U--Pb geochronological data from zircon and monazite [...]

Abstract: The Morrison porphyry Cu-Au-Mo deposit is genetically and spatially related to Eocene plagioclase-hornblende-biotite porphyry intrusions. One porphyry intrusion yielded a U-Pb age of 52.54 ± 1.05 Ma. Mineralization occurs [...]

Newton is an intermediate-sulfidation epithermal gold deposit related to Late Cretaceous continental-arc magmatism in south-central British Columbia. Disseminated gold mineralization occurs in quartz-sericite-altered Late Cretaceous felsic volcanic rocks, and feldspar-quartz-hornblende porphyry and quartz-feldspar porphyry intrusions. The mineralization can be divided into three stages: (1) disseminated pyrite with microscopic gold inclusions, and sparse quartz-pyrite ± molybdenite veins; (2) disseminated marcasite with microscopic gold inclusions and minor base-metal sulfides; and (3) polymetallic veins of pyritechalcopyrite-sphalerite-arsenopyrite. Re-Os dating of molybdenite from a stage 1 vein yielded an age of 72.1 ± 0.3 Ma (published by McClenaghan in 2013). The age of the host rocks has been constrained by U-Pb dating of zircon: Late Cretaceous felsic volcanic rocks, 72.1 ± 0.6 Ma (Amarc Resources Ltd., unpublished data, reported by McClenaghan in 2013); feldspar-quartz- hornblende porphyry, 72.1 ± 0.5 Ma; quartz-feldspar porphyry, 70.9 ± 0.5 Ma (Amarc Resources Ltd., unpublished data, reported by McClenaghan in 2013). The mineralized rocks are intruded by a barren diorite, with an age of 69.3 ± 0.4 Ma. Fluid inclusions in quartz- pyrite ± molybdenite ± gold veins yielded an average homogenization temperature of 313 ± 51°C (number of samples, n = 82) and salinity of 4.8 ± 0.9 wt.% NaCl equiv. (n = 46), suggesting that a relatively hot and saline fluid likely of magmatic origin was responsible for the first stage of mineralization. Some evidence for boiling was also observed in the veins. However, the bulk of the gold mineralization occurs as disseminations in the wall rocks, suggesting that wall-rock reactions were the main control on ore deposition. Le gisement Newton est un gisement epithermal aurifere a sulfuration intermediate relie au magmatisme d'arc continental au Cretace tardif dans le centre-sud de la Colombie-Britannique. La mineralisation aurifere est disseminee dans des roches volcaniques felsiques alterees en quartz-sericite (Cretace tardif) et dans des intrusions de porphyres feldspath-quartzhornblende et de porphyres quartz-feldspath. La mineralisation peut etre divisee en trois stages: (1) de la pyrite disseminee avec des inclusions d'or microscopiques et des filons clairsemes de quartz-pyrite ± molybdenite; (2) de la marcasite disseminee avec des inclusions d'or microscopiques et des quantites mineures de sulfures de metaux de base; et (3) des filons polymetalliques de pyrite-chalcopyrite-sphalerite-arsenopyrite. La datation Re-Os de la molybdenite d'un filon de stage 1 a donne un age de 72.1 ± 0,3 Ma (publie par McClenaghan en 2013). L'age des roches encaissantes a ete contraint par la datation U- Pb du zircon : des roches volcaniques felsiques du Cretace tardif donnant 72,1 ± 0,6 Ma (Amarc Resources Ltd., donnees non publiees, rapportees par McClenaghan en 2013); un porphyre feldspath-quartz-hornblende donnant 72,1 ± 0,5 Ma; un porphyre quartzfeldspath donnant 70,9 ± 0,5 Ma (Amarc Resources Ltd., donnees non publiees, rapportees par McClenaghan en 2013). Une diorite sterile, agee de 69,3 ± 0,4 Ma, penetre les roches mineralisees. Des inclusions de fluides dans les filons quartz-pyrite ± molybdenite ± or ont donne une temperature moyenne d'homogeneisation de 313 ± 51°C (nombre d'echantillons, n = 82) et une salinite de 4,8 [+ or -] 0,9 % (equivalence en poids de NaCl) (n = 46), suggerant qu'un fluide relativement chaud et salin, probablement d'origine magmatique, soit responsable du premier stage de mineralisation. Une certaine evidence d'ebullition a aussi ete observee dans les filons. Toutefois, l'ensemble de la mineralisation aurifere se presente sous forme de disseminations dans les roches encaissantes suggerant que les reactions des roches encaissantes aient constitue le controle principal sur la deposition du minerai. [Traduit par la Redaction], Introduction The Newton gold deposit is a significant new discovery in southern British Columbia. It is located roughly 110 km southwest of Williams Lake at 51°47'N and 123°36'W (Fig. 1). [...]

Cambrian to Ordovician metamorphosed clastic sedimentary rocks of the Meguma terrane have no correlatives elsewhere in Atlantic Canada but are similar to successions in North Wales. In the Meguma terrane, the Cambrian Goldenville Group, dominated by sandstone, is overlain by the Halifax Group, consisting mainly of fine-grained slate and siltstone. Within the Halifax Group widespread Furongian black slate units are overlain by greyer units with rare Early Ordovician fossils, assigned to the laterally equivalent Bear River, Feltzen, Bluestone Quarry, Lumsden Dam and Glen Brook formations. The type section of the Bluestone Quarry Formation, here defined, is on Halifax Peninsula, where four constituent members are recognized; the type section of the Lumsden Dam Formation is here defined in the Lumsden Dam region near Wolfville. Detrital zircons extracted from a sample of the Lumsden Dam Formation show a range of ages similar to those displayed by the underlying Goldenville Group, including abundant Neoproterozoic zircon representing Avalonian or Pan-African sources, and a prominent group of peaks between 1.95 and 2.2 Ga, probably representing sources in West Africa. A sample from the Glen Brook Formation east of Halifax shows a similar distribution. In contrast to the correlative Welsh successions, no influx of Mesoproterozoic zircon is seen in Early Ordovician samples, suggesting that, if the two basins were in close proximity in the Cambrian, they had diverged by the Early Ordovician, possibly as a result of strike-slip motion along the margin of Gondwana. Les roches sedimentaires clastiques metamorphisees du Cambrien a l'Ordovicien du terrane de Meguma nont pas de correlatif ailleurs au Canada atlantique, mais sont semblables a des successions observees en Galles du Nord. Dans le terrane de Meguma, le groupe de Goldenville du Cambrien, a predominance de gres, est reconvert du groupe d'Halifax, pour sa part compose principalement de siltite et d'ardoise a grains fins. Au sein du groupe d'Halifax, d'importantes unites d'ardoise noire du Furongien sont recouvertes d'unites plutot grises et de rares fossiles de l'Ordovicien precoce attribues aux formations lateralement equivalentes de Bear River, de Feltzen, de Bluestone Quarry, de Lumsden Dam et de Glen Brook. Le stratotype de la formation de Bluestone Quarry est ici defini comme se trouvant sur la peninsule d'Halifax, ou on reconnait quatre membres constitutifs, tandis que le stratotype de la formation de Lumsden Dam est ici defini comme se trouvant dans la region de Lumsden Dam, pres de Wolfville. Des zircons detritiques extraits d'un echantillon de la formation de Lumsden Dam revelent differents ages semblables a ceux du groupe de Goldenville sousjacent. On y trouve notamment une abondance de zircon du Neoproterozo'ique representant des sources avaloniennes ou pan-africaines et un groupe proeminent de pics ages de 1,95 a 2,2 Ga representant probablement des sources de l'Afrique de l'Ouest. Un echantillon de la formation de Glen Brook, situee a l'est d'Halifax, revele une distribution semblable. A la difference des successions du Pays de Galles qui y sont liees, aucun afflux de zircon du Mesoproterozoique nest observe dans les echantillons de l'Ordovicien precoce, ce qui tend a indiquer que les deux bassins, qui etaient situes tout pres au Cambrien, se sont eloignes a l'Ordovicien precoce, vraisemblablement a la suite d'un mouvement de decrochement le long de la limite de Gondwana. [Traduit par la redaction], INTRODUCTION Metamorphosed clastic sedimentary rocks of the Meguma terrane (Fig. 1), the most outboard terrane of the Canadian Appalachians, have no correlatives elsewhere in Atlantic Canada, and their source has [...]

The Red Chris porphyry Cu-Au deposit is located in the Stildnia island-arc terrane in northwest Br itish Columbia. It is hosted by the Red Stock, which has five phases of porphyry intrusions: PI, P2E, P2I, P2L, and P3. New U-Pb dating of zircon shows that these intrusions were emplaced over a ~10 m.y. period, with PI intruded at 211.6 ± 1.3 Ma (MSWD = 0.85), P2I at 206.0 ± 1.2 Ma (MSWD = 1.5), P2L at 203.6 ± 1.8 Ma (MSWD = 1.5), and P3 at 201.7 ± 1.2 Ma (MSWD = 1.05). The ore-forming event at Red Chris was a short-lived event at 206.1 ± 0.5 Ma (MSWD = 0.96; weighted average age of three Re-Os molybdenite analyses), implying a duration of <1 m.y., as defined by the uncertainty range, coincident with the emplacement age of the P2 porphyries. Zircons from PI to P3 porphyry rocks have consistently high E un/E un 0.4), indicating that their associated magmas were moderately oxidized. The magmatic water contents estimated from plagioclase and amphibole compositions suggest ILO contents of ~5 wt %. Taken together, the PI to P3 poiphyries are interpreted to be moderately oxidized and hydrous. The porphyry phases are differentiated by sulfur and chlorine contents. The SCR contents of igneous apatite microphenocrysts from the mineralization-related P2 porphyries are higher (P2E: 0.28 ± 0.10 wt %, n = 19; P2I: 0.32 + 0.17, n = 15; P2L: 0.29 ± 0.18 wt %, n = 100) than those from the premineralization PI (0.11 ± 0.03 wt %, n = 34) and postmineralization P3 porphyries (0.03 ± 0.01 wt %, n = 13). The chlorine contents in apatite grains from the P2E, P2I, and P2L porphyries are 1.47 ± 0.22 (n = 19), 0.82 ± 0.10 (n = 15), and 1.47 ± 0.28 wt % (n = 100), also higher than those from PL (0.51 ± 0.3 wt % Cl, n = 34) and P3 (0.02 ± 0.02 wt % Cl, n = 17). These results imply that the sulfur and chlorine contents of the P2 magmas were higher than in the PI and P3 magmas, suggesting that elevated magmatic S-Cl contents in the P2 poiphvries may have been important for ore formation. Although the process that caused the increase in sulfur and chlorine is not clear, reverse zoning seen in plagioclase phenocrysts from the P2 porphyry, and the occurrence of more mafic compositions in P2L suggest that recharge of the deeper magma chamber by a relatively S-Cl-rich mafic magma may have triggered the ore-forming hydrothermal event. [ABSTRACT FROM AUTHOR]