U–Pb geochronological constraints on the timing of episodic regional metamorphism and rapid high-T exhumation of the Grand Forks complex, British Columbia

Cubley, Joel F.; Pattison, David R.M.; Tinkham, Douglas K.

doi:10.1016/j.lithos.2012.10.015

Cited by 15 publications

(9 citation statements)

References 79 publications

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“…Kohn, 2014), but the tight path inferred here contrasts with more "open" P-T paths commonly inferred from many Phanerozoic orogenic belts which record heating at greater initial depths followed by more extensive HT decompression (e.g. Cubley, Pattison, Tinkham, & Fanning, 2013;Kohn, 2014;Sorcar, Hoppe, Dasgupta, & Chakraborty, 2014;Stevens et al, 2015;Yakymchuk et al, 2015). We note, however, that tight clockwise P-T paths characterized by limited HT decompression (~1 kbar or less) have been inferred from various settings interpreted to result from orogenic processes (e.g.…”

Section: Ht Metamorphismcontrasting

confidence: 78%

Rapid high‐T decompression recorded by Archean granulites in the northern Wyoming Province: Insights from petrological modelling

Guevara

Caddick

Dragovic

2017

Journal Metamorphic Geology

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This study places new constraints on the pressure–temperature (P–T) path and duration of high‐temperature (HT) metamorphism recorded by Archean granulite facies metasedimentary rocks from the northern Wyoming Province in the eastern Beartooth Mountains, MT and WY, USA. These rocks exist as m‐ to km‐scale xenoliths within a c. 2.8 Ga calc‐alkaline granitoid batholith. Different interpretations of the timing of HT metamorphism relative to batholith intrusion in previous works have led to ambiguity over the mechanism by which these rocks were heated (i.e. batholith intrusion v. a later, cryptic event). The P–T path recorded by these rocks and the duration of this path may be indicative of the heating mechanism but are not currently well constrained. Here, we combine phase equilibria thermobarometry and diffusion modelling of major element zonation in garnet in order to constrain the P–T path of HT metamorphism and the durations of different parts of this path. It is shown that these rocks record a tight, clockwise P–T path characterized by near‐isobaric heating at ~6.5–7 kbar to ˜770–800°C, HT decompression to ~6 kbar, 780–800°C, followed by limited decompression while cooling. Diffusion modelling of major element zonation in garnet suggests that HT decompression was brief (likely <1 Ma), and that cooling rates following this decompression were on the order of 10–100°C/Ma. Substantial changes in apparent thermal gradient along this P–T path indicate that the rocks record a significant but short‐lived thermal anomaly that occurred in the Wyoming mid‐crust in the Late Archean.

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Section: Ht Metamorphismcontrasting

confidence: 78%

Rapid high‐T decompression recorded by Archean granulites in the northern Wyoming Province: Insights from petrological modelling

Guevara

Caddick

Dragovic

2017

Journal Metamorphic Geology

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“…In other studies, yttrium has primarily been utilised as an independent proxy for identifying different age domains within the monazite grains (e.g. Cubley et al, 2013;Cutts et al, 2013;Mahan et al, 2006;Pyle and Spear, 2003;Reno et al, 2012;Williams et al, 2007). However, the results obtained in this study suggest no apparent systematic relationship between age and internal compositional variability.…”

Section: La-icp-ms Monazite Geochronologymentioning

confidence: 64%

A duality of timescales: Short-lived ultrahigh temperature metamorphism preserving a long-lived monazite growth history in the Grenvillian Musgrave–Albany–Fraser Orogen

Tucker

Hand

Kelsey

et al. 2015

Precambrian Research

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“…61–49 Ma in the Okanogan dome (Kruckenberg et al ., ), c . 50 Ma in the Grand Forks complex (Cubley et al ., ) and c . 54–44 Ma in the PRC.…”

Section: Discussionmentioning

confidence: 99%

“…Similarly, the timing of melt crystallization recorded by monazite is c. 56-51 Ma in the Thor-Odin dome (Hinchey et al, 2006), c. 60-50 Ma in the Valhalla dome (Gordon et al, 2008), c. 61-49 Ma in the Okanogan dome (Kruckenberg et al, 2008), c. 50 Ma in the Grand Forks complex (Cubley et al, 2013) and c. 54-44 Ma in the PRC. While the initiation of melt crystallization varies somewhat, melt crystallization ceases latest in the PRC.…”

mentioning

confidence: 82%

Phase equilibria modelling and LASS monazite petrochronology: P–T–t constraints on the evolution of the Priest River core complex, northern Idaho

Stevens

Baldwin

Cottle

et al. 2015

Journal Metamorphic Geology

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Phase equilibria modelling, laser‐ablation split‐stream (LASS)‐ICP‐MS petrochronology and garnet trace‐element geochemistry are integrated to constrain the P–T–t history of the footwall of the Priest River metamorphic core complex, northern Idaho. Metapelitic, migmatitic gneisses of the Hauser Lake Gneiss contain the peak assemblage garnet + sillimanite + biotite ± muscovite + plagioclase + K‐feldspar ± rutile ± ilmenite + quartz. Interpreted P–T paths predict maximum pressures and peak metamorphic temperatures of ~9.6–10.3 kbar and ~785–790 °C. Monazite and xenotime 208Pb/232Th dates from porphyroblast inclusions indicate that metamorphism occurred at c. 74–54 Ma. Dates from HREE‐depleted monazite formed during prograde growth constrain peak metamorphism at c. 64 Ma near the centre of the complex, while dates from HREE‐enriched monazite constrain the timing of garnet breakdown during near‐isothermal decompression at c. 60–57 Ma. Near‐isothermal decompression to ~5.0–4.4 kbar was followed by cooling and further decompression. The youngest, HREE‐enriched monazite records leucosome crystallization at mid‐crustal levels c. 54–44 Ma. The northernmost sample records regional metamorphism during the emplacement of the Selkirk igneous complex (c. 94–81 Ma), Cretaceous–Tertiary metamorphism and limited Eocene exhumation. Similarities between the Priest River complex and other complexes of the northern North American Cordillera suggest shared regional metamorphic and exhumation histories; however, in contrast to complexes to the north, the Priest River contains less partial melt and no evidence for diapiric exhumation. Improved constraints on metamorphism, deformation, anatexis and exhumation provide greater insight into the initiation and evolution of metamorphic core complexes in the northern Cordillera, and in similar tectonic settings elsewhere.

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U–Pb geochronological constraints on the timing of episodic regional metamorphism and rapid high-T exhumation of the Grand Forks complex, British Columbia

Cited by 15 publications

References 79 publications

Rapid high‐T decompression recorded by Archean granulites in the northern Wyoming Province: Insights from petrological modelling

Rapid high‐T decompression recorded by Archean granulites in the northern Wyoming Province: Insights from petrological modelling

A duality of timescales: Short-lived ultrahigh temperature metamorphism preserving a long-lived monazite growth history in the Grenvillian Musgrave–Albany–Fraser Orogen

Phase equilibria modelling and LASS monazite petrochronology: P–T–t constraints on the evolution of the Priest River core complex, northern Idaho

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