Update on bedrock geological mapping of the Yukon-Tanana terrane, southern Stewart River map area, Yukon Territory

Ryan, James J.; Gordey, S P; Glombick, P; Piercey, Stephen J.; Villeneuve, M.

doi:10.4095/214026

Cited by 8 publications

(10 citation statements)

References 10 publications

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“…Amphibolite with arc tholeiitic affi nities Piercey et al, 2003b) stratigraphically overlies, and structurally interfi ngers with, the metasiliciclastic rocks, and marble horizons are found in both the amphibolite and metasiliciclastic rocks Gordey, 2001, 2002;Ryan et al, 2003). Local occurrences of metamorphosed gabbro are interpreted to be comagmatic with the amphibolite (Piercey et al, 2003b;Gordey, 2001, 2002;Ryan et al, 2003). The amphibolite and metasiliciclastic rocks are intruded by a complex of early Mississippian calc-alkalic , metaluminous plutonic to orthogneissic rocks (Figs.…”

Section: Regional Geological Settingmentioning

confidence: 99%

“…This package consists predominantly of psammite and quartzite, with lesser amounts of pelite and rare conglomerate Gordey, 2001, 2002;Ryan et al, 2003). Amphibolite with arc tholeiitic affi nities Piercey et al, 2003b) stratigraphically overlies, and structurally interfi ngers with, the metasiliciclastic rocks, and marble horizons are found in both the amphibolite and metasiliciclastic rocks Gordey, 2001, 2002;Ryan et al, 2003). Local occurrences of metamorphosed gabbro are interpreted to be comagmatic with the amphibolite (Piercey et al, 2003b;Gordey, 2001, 2002;Ryan et al, 2003).…”

Section: Regional Geological Settingmentioning

confidence: 99%

“…2 and 3). This metaplutonic complex is interpreted to represent an early Mississippian subvolcanic intrusive complex, is composed of metamorphosed diorite, tonalite, granodiorite, and monzogranite, and is equivalent to the Simpson Range plutonic suite Gordey, 2001, 2002;Ryan et al, 2003).…”

Section: Regional Geological Settingmentioning

confidence: 99%

“…The early Mississippian suite of augen granitoids is coeval with the early Mississippian granitic orthogneiss, and the Permian suite forms a younger intrusive suite that intrudes all these older rocks, and is coeval with similar Permian plutonic rocks (Sulfur Creek orthogneiss) and metavolcanic rocks (Klondike Schist) near the Dawson City region to the north (e.g., Mortensen, 1990). The Permian suite is interpreted to represent a separate Late Permian volcano-plutonic arc complex (e.g., Mortensen, 1990Mortensen, , 1992Ryan et al, 2003). (Fig.…”

Section: Regional Geological Settingmentioning

confidence: 99%

“…Although attempts were made to collect leastaltered samples, fi eld and petrographic data for the augen granitoids illustrate that they have been exposed to variably intense polyphase deformation and amphibolite facies metamorphism, with local greenschist-grade metamorphic overprints Gordey, 2001, 2002;Ryan et al, 2003). Given these metamorphic conditions, most major elements (e.g., SiO 2 , Na 2 O, K 2 O, and CaO) and low fi eld strength elements (LFSE: Cs, Rb, Ba, Sr) may have been mobilized to varying degrees (MacLean, 1990).…”

Section: Alteration Metamorphism and Element Mobilitymentioning

confidence: 99%

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Mid- to late Paleozoic K-feldspar augen granitoids of the Yukon-Tanana terrane, Yukon, Canada: Implications for crustal growth and tectonic evolution of the northern Cordillera

Ruks¹,

Piercey²,

Ryan³

et al. 2006

Geological Society of America Bulletin

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Potassic feldspar-bearing augen granitoids are a fundamental component of the architecture of the Yukon-Tanana terrane and the ancient Pacifi c margin of the northern Cordillera. These augen granitoids form a belt that extends from Alaska to southeast Yukon Territory, vary in age, and provide probes of the crustal evolution and tectonic history of the Yukon-Tanana terrane and ancient Pacifi c margin of North America in the Paleozoic. We present results of an integrated fi eld mapping, geochemical, Sm-Nd tracer isotopic, and U-Pb zircon geochronologic study of the augen granitoids in the Stewart River area in an attempt to understand their role in the crustal evolution and tectonic history of the Yukon-Tanana terrane and ancient Pacifi c margin of North America.Augen granitoids of the Stewart River area are of three distinct ages: Late Devonian, early Mississippian, and Permian. U-Pb zircon geochronology of these augen granitoids has yielded ages of 362.1 ± 2.7 Ma (Stewart River augen granite), 347.5 ± 0.7 Ma (Mount Burnham augen granite), and 264.8 ± 3.7 Ma (Wounded Moose augen granite). All of the augen granitoids, regardless of age, have negative ε Ndt values (−2.0 to −15.3) and Proterozoic-Archean depleted-mantle model ages (T DM = 1.37-2.56 Ga). These geochemical and isotopic attributes, coupled with the presence of inherited zircon with Precambrian ages, suggest that these granitoids are the product of crustal melting and crust-mantle mixing during three different cycles of arc magmatism in the Paleozoic. Furthermore, these granitoids represent net crustal recycling along the ancient Pacifi c margin of North America in the Paleozoic. Importantly, however, there are minor secular variations in crustal recycling, and the younger Permian augen granitoids exhibit higher ε Ndt , Nb/Ta, V/Yb, and Sc/Yb, consistent with a greater juvenile component in their genesis. This juvenile component is probably due to assimilation of underplated mafi c material derived from older early Mississippian Yukon-Tanana terrane arc magmatism and/or a greater mantle component due to enhanced infi ltration of underplated mafi c material into augen granitoid magma chambers through rheologically weak crust associated with Permian subduction.The older Late Devonian and early Mississippian augen granitoid suites represent two pulses of Yukon-Tanana terrane arc magmatic activity that developed in response to east-dipping subduction along the western edge of the North America craton in the mid-Paleozoic. This east-dipping Yukon-Tanana terrane arc system continued to evolve throughout the Mississippian to Early Permian and was coincident with the development of the Slide Mountain backarc basin that formed between the Yukon-Tanana terrane arc system and the North American craton; this east-dipping arc-backarc system continued until ca. 275 Ma. After ca. 275 Ma, the east-dipping arc and backarc magmatism ceased and was replaced by ca. 270-269 Ma high-pressure metamorphism and the establishment of a new subduction zone that formed in response t...

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Section: Regional Geological Settingmentioning

confidence: 99%

Section: Regional Geological Settingmentioning

confidence: 99%

Section: Regional Geological Settingmentioning

confidence: 99%

Section: Regional Geological Settingmentioning

confidence: 99%

Section: Alteration Metamorphism and Element Mobilitymentioning

confidence: 99%

See 3 more Smart Citations

Mid- to late Paleozoic K-feldspar augen granitoids of the Yukon-Tanana terrane, Yukon, Canada: Implications for crustal growth and tectonic evolution of the northern Cordillera

Ruks¹,

Piercey²,

Ryan³

et al. 2006

Geological Society of America Bulletin

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Zircon and the role of magmatic petrogenesis in the formation of felsic-hosted volcanogenic massive sulfide (VMS) deposits: a case study from the mid-Paleozoic Yukon-Tanana terrane, northern Canadian Cordillera

Manor,

Piercey,

Wall

2023

Miner Deposita

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Magmatism is a critical component in sustaining hydrothermal convection and metal transport during the formation of volcanogenic massive sulfide (VMS) deposits. Previous studies of magmatic petrogenesis in VMS systems have demonstrated that ore-related volcanic rocks have distinct whole-rock geochemical and isotopic signatures (i.e., high HFSE, REE, Th, εHf-Nd, zircon saturation T) relative to barren volcanic rocks, which supports models of elevated crustal heat flow during periods of ore deposition; however, the petrologic characteristics and intrinsic parameters (e.g., T, fO2) related to these magmatic events in VMS districts remain poorly understood. Arc–back-arc assemblages from the mid-Paleozoic Yukon-Tanana terrane are well-characterized and include the Finlayson Lake VMS district, which is host to several felsic-hosted deposits (e.g., Kudz Ze Kayah, GP4F, Wolverine) that were generated in a peri-Laurentian continental back-arc tectonic setting. In this study, zircon from back-arc and coeval arc rocks in the Yukon-Tanana terrane was used as a proxy for primary magma formation conditions that generated VMS-proximal and VMS-distal stratigraphy. Our results indicate that zircon grains in VMS-proximal environments have unique textural, geochemical, and isotopic characteristics (e.g., low-aspect ratios, greater abundance of zircon-phosphate intergrowths, Th/U > 1, Zr/Hf > 80, Tzrc > 780 °C, εHfi > –7) that are clearly distinguished from zircon in VMS-distal rocks in both the back-arc and arc settings (Th/U < 1, Zr/Hf < 80, Tzrc < 780 °C, εHfi < –7). These signatures correlate to VMS-proximal magmas that were hotter, less fractionated, and contained greater juvenile melt contributions compared to VMS-distal magmas and reflect a series of high-flux magmatic events that directly correspond to the early tectonic development of Yukon-Tanana terrane. Moreover, this study underscores the importance of mineral-scale petrology, geochemistry, and geochronology in defining the primary magmatic conditions that generated VMS-related felsic rocks and highlights the utility of zircon as a prospectivity tool in both grassroots and brownfields VMS exploration.

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Permian to Cretaceous polymetamorphic evolution of the Stewart River region, Yukon‐Tanana terrane, Yukon, Canada: P–T evolution linked with in situ SHRIMP monazite geochronology

Berman

Ryan

Gordey

et al. 2007

Journal Metamorphic Geology

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Textural relationships and the trace element chemistry of accessory minerals and garnet can provide the linkage between in situ SHRIMP ages and quantitative pressure-temperature data that is required to decipher complex polymetamorphic and polydeformational histories. Application of these methods to lower amphibolite facies rocks of the Stewart River area, Yukon (Canada) yields robust new constraints on the tectonic evolution of central Yukon Tanana Terrane (YTT). A TIMS U/Pb titanite age of 365-350 Ma is interpreted to date low-P metamorphism (M1) and D1 deformation associated with arc plutonism above an east-dipping subduction zone. Monazite inclusions in garnet porphyroblasts record a transition from low to high pressure ($9 kbar and 600°C) at c. 239 Ma. These data help to establish a c. 260-240 Ma tectonometamorphic event (M2-D2) reflecting intra-arc thickening during west-dipping subduction of Slide Mountain Ocean. Another transition from low-to high-P (M3-D3; 7.8 kbar and 595°C), dated by c. 195-187 Ma monazite, is interpreted to reflect the change from regional contact metamorphism during arc plutonism to internal duplication of YTT during initial collision of YTT with the North American craton. The Mt Burnham (north-eastern) region records a different history because of its proximity to later plutons and its late exhumation via extensional faulting. Monazite growth at 146 Ma dates $9 kbar metamorphism (M4), interpreted to reflect a previously unrecognized period of plutonism associated with auriferous quartz veins in the Klondike region. Monazite growth at 114-107 Ma reflects low-P (<4.6 kbar) contact metamorphism (M5) accompanying regional plutonism and extension.

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Update on bedrock geological mapping of the Yukon-Tanana terrane, southern Stewart River map area, Yukon Territory

Cited by 8 publications

References 10 publications

Mid- to late Paleozoic K-feldspar augen granitoids of the Yukon-Tanana terrane, Yukon, Canada: Implications for crustal growth and tectonic evolution of the northern Cordillera

Mid- to late Paleozoic K-feldspar augen granitoids of the Yukon-Tanana terrane, Yukon, Canada: Implications for crustal growth and tectonic evolution of the northern Cordillera

Zircon and the role of magmatic petrogenesis in the formation of felsic-hosted volcanogenic massive sulfide (VMS) deposits: a case study from the mid-Paleozoic Yukon-Tanana terrane, northern Canadian Cordillera

Permian to Cretaceous polymetamorphic evolution of the Stewart River region, Yukon‐Tanana terrane, Yukon, Canada: P–T evolution linked with in situ SHRIMP monazite geochronology

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