Tectonic affinity of Nisutlin and Anvil assemblage strata from the Teslin tectonic zone, northern Canadian Cordillera: Constraints from neodymium isotope and geochemical evidence

Creaser, Robert A.; Erdmer, Philippe; Stevens, Robert A.; Grant, Steven

doi:10.1029/96tc03317

Cited by 86 publications

(67 citation statements)

References 41 publications

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“…These zircon grains record a high-pressure metamorphic age of 266 ± 3 to 265 ± 4 Ma, which agrees with the SIMS ages (271-267 Ma) determined for eclogite (Petrie 2014) and the U-Pb TIMS zircon age of 266 ± 0.6 Ma derived from eclogite (Fallas et al 1998). These dates are also within error of a U-Pb zircon age interpreted to record the high-pressure metamorphism of eclogite at Last Peak (269 ± 2 Ma; Creaser et al 1997), and corroborate other Permian eclogite-facies assemblages attributed to the Yukon-Tanana terrane.…”

Section: Discussionsupporting

confidence: 79%

“…Phengite is confirmed in eclogite from Ross River and Faro (Erdmer 1987;Perchuk et al 1999). Like eclogite at St. Cyr, during the transition from eclogite to garnet amphibolite, omphacite was replaced primarily by calcic amphibole, such as pargasite, and albitic plagioclase (Erdmer and Helmstaedt 1983;Erdmer 1987;Creaser et al 1997;Perchuk et al 1999). Geochemically, the MORB signature recorded in the major and trace element geochemistry of St. Cyr eclogite is consistent with the geochemical signatures of eclogite at all three localities (Erdmer and Helmstaedt 1983;Creaser et al 1999;Pigage 2004;Ghent and Erdmer 2011).…”

Section: Discussionsupporting

confidence: 59%

“…These rocks bear a resemblance to the host rocks in the St. Cyr klippe, although the amphibole is less sodic at St. Cyr. At each of the three other localities, the peak eclogite-facies assemblage is omphacite + garnet + quartz, which is the dominant peak assemblage at St. Cyr (Creaser et al 1997;Erdmer et al 1998). Phengite is confirmed in eclogite from Ross River and Faro (Erdmer 1987;Perchuk et al 1999).…”

Section: Discussionmentioning

confidence: 87%

“…These high-pressure mafic bodies are interpreted to have formed in a tectonic mélange with serpentinized ultramafic and gabbroic rocks and low-grade basalt, chert, limestone and chlorite-schist interpreted to be derived from Yukon-Tanana terrane basement and early YukonTanana arc rocks (Erdmer 1987;Erdmer et al 1998;Devine et al 2006). In addition to the St. Cyr area, Permian age highpressure rocks are found at Ross River, Faro and Last Peak (Erdmer and Armstrong 1989;Creaser et al 1997;. At these localities, eclogite and variably retrogressed equivalent rocks form metre-to tens of metres-sized lenses or structurally conformable layers hosted by greenschist-, blueschist-, or amphibolite-facies schist and quartzite (Erdmer and Helmstaedt 1983;Erdmer 1987;Erdmer et al 1998).…”

Section: Regional Geologic Settingmentioning

confidence: 99%

“…At these localities, eclogite and variably retrogressed equivalent rocks form metre-to tens of metres-sized lenses or structurally conformable layers hosted by greenschist-, blueschist-, or amphibolite-facies schist and quartzite (Erdmer and Helmstaedt 1983;Erdmer 1987;Erdmer et al 1998). Structural fabrics shared by the eclogite and the host rocks led to the suggestion that they were in contact prior to peak metamorphism (Erdmer and Helmstaedt 1983;Erdmer 1987;Creaser et al 1997;Erdmer et al 1998). …”

Section: Regional Geologic Settingmentioning

confidence: 99%

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Geologic Setting of Eclogite-facies Assemblages in the St. Cyr Klippe, Yukon–Tanana Terrane, Yukon, Canada

Petrie

Gilotti

McClelland

et al. 2015

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SUMMARYThe St. Cyr area near Quiet Lake hosts well-preserved to variably retrogressed eclogite found as sub-metre to hundreds of metre-long lenses within quartzofeldspathic schist in southcentral Yukon, Canada. The St. Cyr klippe consists of structurally imbricated, polydeformed and polymetamorphosed units of continental arc crust and ultramafic-mafic rocks. Eclogite-bearing quartzofeldspathic schist forms thrust slices in a 30 km long by 6 km wide, northwest-striking outcrop belt. The schist unit comprises metasedimentary and felsic intrusive rocks that are intercalated on the metre to tens of metres scale. Ultramafic rocks, serpentinite and associated greenschist-facies metagabbro form imbricated tectonic slices within the eclogite-bearing quartzofeldspathic unit, which led to a previously held hypothesis that eclogite was exhumed within a tectonic mélange. The presence of phengite and Permian zircon crystallized under eclogite-facies metamorphic conditions in the quartzofeldspathic host rocks indicate that the eclogite was metamorphosed in situ together with the schist as a coherent unit that was part of the continental arc crust of the Yukon-Tanana terrane, rather than a mélange associated with the subduction of oceanic crust of the Slide Mountain terrane. Petrological, geochemical, geochronological and structural similarities link St. Cyr eclogite to other high-pressure localities within Yukon, indicating the high-pressure assemblages form a larger lithotectonic unit within the Yukon-Tanana terrane. Geoscience Canada, v. 42, http://www.dx

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Section: Discussionsupporting

confidence: 79%

Section: Discussionsupporting

confidence: 59%

Section: Discussionmentioning

confidence: 87%

Section: Regional Geologic Settingmentioning

confidence: 99%

Section: Regional Geologic Settingmentioning

confidence: 99%

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Geologic Setting of Eclogite-facies Assemblages in the St. Cyr Klippe, Yukon–Tanana Terrane, Yukon, Canada

Petrie

Gilotti

McClelland

et al. 2015

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Refinement of the time-space evolution of the giant Mio-Pliocene Río Blanco-Los Bronces porphyry Cu–Mo cluster, Central Chile: new U–Pb (SHRIMP II) and Re–Os geochronology and 40Ar/39Ar thermochronology data

2012

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Artículo de publicación ISIRepresenting one of the largest known (estimated >5 Gt at 1 % Cu and 0.02 % Mo) porphyry system, the Río Blanco-Los Bronces deposit incorporates at least five hypabyssal intrusive and hydrothermal centres, extending for about 5 km from the Río Blanco and Los Bronces mines in the north, through the Don Luis mine, to the Sur Sur mine, La Americana and Los Sulfatos in the south. The new geochronology data, which now include data on differentmolybdenite vein types, confirm the U–Pb ages of the pre-mineralisation intrusions but slightly increase their age range from 8.8 to 8.2 Ma. The distinct magmatic pulses of the mineralisationassociated porphyritic intrusives (Late Porphyries) indicate an age interval instead of the previously suggested individual ages: the quartz monzonite porphyry ranges from 7.7 to 6.1Ma (Sur Sur 5.74±0.13Ma), the feldspar porphyry shows an interval from 5.8 to 5.2 Ma and the Don Luis porphyry from 5.2 to 5.0 Ma. The new Re–Os data on distinct molybdenite vein types confirm the protracted history of Cu(–Mo) mineralisation, inferred previously. The vein development occurred at least from 5.94 to 4.50 Ma, indicating a timespan of 1.5 Ma for the hydrothermal activity. Hydrothermal minerals dated by the 40Ar/39Ar method are generally too young to record the age of early, high-temperature mineralisation. The majority of the 40Ar/39Ar data in the Río Blanco porphyry cluster record reheating by either the youngestmember of the Late Porphyry suite or the post-mineralisation dacite or rhyolite plug formations at around 4.9–4.7 Ma

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Timing and duration of hydrothermal activity at the Los Bronces porphyry cluster: an update

Deckart

Silva²,

Spröhnle³

et al. 2014

Miner Deposita

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Artículo de publicación ISINew geochronological data from the Los Bronces cluster of the Río Blanco-Los Bronces mega-porphyry Cu-Mo district establish a wide range of magmatism, hydrothermal alteration, and mineralization ages, both in terms of areal extent and time. The northern El Plomo and southernmost Los Piches exploration areas contain the oldest barren porphyritic intrusions with U-Pb ages of 10.8±0.1 Ma and 13.4± 0.1 Ma, respectively. A hypabyssal barren intrusion adjacent northwesterly to the main pit area yields a slightly younger age of 10.2±0.3 Ma (San Manuel sector, U-Pb), whereas in the Los Bronces (LB) open-pit area, the present day mineral extraction zone, porphyries range from 8.49 to 6.02 Ma (UPb). Hydrothermal biotite and sericite ages are up to 0.5 Ma younger but consistent with the cooling of the corresponding intrusion events of each area. Two quartz-molybdenite B-type veins from the LB open pit have Re-Os molybdenite ages of 5.65±0.03 Ma and 5.35±0.03 Ma consistent with published data for the contiguous Río Blanco cluster. The San Manuel exploration area within the Los Bronces cluster, located about 1.5–2 km southeast of the open-pit extraction zone, shows both the oldest hydrothermal biotite (7.70±0.07 Ma; 40Ar/39Ar) and breccia cement molybdenite ages (8.36± 0.06 Ma; Re-Os) registered in the entire Río Blanco-Los Bronces district. These are also older than those reported from the El Teniente porphyry Cu(-Mo) deposit, suggesting that mineralization in the late Miocene to early Pliocene porphyry belt of Central Chile commenced 2 Ma before the previously accepted age of 6.3 Ma.This study has been financed by Anglo American Chile

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Tectonic affinity of Nisutlin and Anvil assemblage strata from the Teslin tectonic zone, northern Canadian Cordillera: Constraints from neodymium isotope and geochemical evidence

Cited by 86 publications

References 41 publications

Geologic Setting of Eclogite-facies Assemblages in the St. Cyr Klippe, Yukon–Tanana Terrane, Yukon, Canada

Geologic Setting of Eclogite-facies Assemblages in the St. Cyr Klippe, Yukon–Tanana Terrane, Yukon, Canada

Refinement of the time-space evolution of the giant Mio-Pliocene Río Blanco-Los Bronces porphyry Cu–Mo cluster, Central Chile: new U–Pb (SHRIMP II) and Re–Os geochronology and 40Ar/39Ar thermochronology data

Timing and duration of hydrothermal activity at the Los Bronces porphyry cluster: an update

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