Atomistic simulations of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si56.svg"><mml:mrow><mml:msup><mml:mrow/><mml:mrow><mml:mn>40</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>Ar diffusion in muscovite

Nteme, Jehiel; Scaillet, Stéphane; Brault, Pascal; Tassan‐Got, L.

doi:10.1016/j.gca.2022.05.004

Cited by 11 publications

(14 citation statements)

References 125 publications

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“…Our interpretation is that the micas with Xcel > 0.3 are porphyroclasts inherited from an early event (≥ 600 Ma) while the younger age of the Xcel < 0.2 micas record a younger fluid-rock interaction event responsible for the growth of secondary white micas and chlorite between 250 and 350 °C during top to the east deformation. That temperature is lower than the closure temperature of white micas for the K/Ar system of 400-445 °C (Harrison et al, 2009) and recently revised theoretical and empirical estimates (Nteme et al, 2022(Nteme et al, , 2023 implying that the 15.4 ± 0.2 Ma (middle Miocene) age correspond to white mica crystallization, not cooling.…”

Section: J O U R N a L P R E -P R O O Fmentioning

confidence: 87%

Cenozoic kinematics of the Wenchuan-Maoxian fault implies crustal stacking rather than channel flow extrusion at the eastern margin of Tibetan plateau (Longmen Shan)

et al. 2023

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Section: J O U R N a L P R E -P R O O Fmentioning

confidence: 87%

Cenozoic kinematics of the Wenchuan-Maoxian fault implies crustal stacking rather than channel flow extrusion at the eastern margin of Tibetan plateau (Longmen Shan)

et al. 2023

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“…This is true in particular for the white mica group for which a large range of closure temperature is suggested by different studies, from 350 to 550 °C or more [e.g. Hames and Bowring, 1994, Harrison et al, 2009, Nteme et al, 2022, a range which remains an area for future exploration. As a consequence, the reconstruction of P -T -D-t path in polydeformed high-temperature rocks using 40 Ar/ 39 Ar data can suffer from this indetermination of the retention properties of the dated minerals and for this purpose the use of multiple geochronometers is highly recommended.…”

Section: Age Interpretationmentioning

confidence: 98%

40 Ar/ 39 Ar geochronology of crustal deformation

Monié,

Münch,

Milesi

et al. 2024

Comptes Rendus. Géoscience

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Crustal deformation is characterized by brittle and ductile faults that accommodate at different scales the strain imposed by plate tectonics. The aim of this contribution is to show with the help of different examples how the in situ 40 Ar/ 39 Ar dating of synkinematic neocrystallized minerals in ductile shear zones and the step-heating 40 Ar/ 39 Ar dating of synkinematic authigenic clays in fault gouges can bring information on the timing of fault activity. However, due to their complex evolution, interpretation of the argon signature in fault zones requires consideration of several effects among which re-or neocrystallization, inheritance and fluid interaction processes are dominant.

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“…A growing number of studies have shown by combining in situ 40 Ar/ 39 Ar dating with petrological characterisation and occasionally Rb-Sr dating that fluid-mediated recrystallisation dominates 40 Ar redistribution in muscovite [42][43][44]. Furthermore, it has been recently demonstrated by atomistic simulations that 40 Ar diffusion in muscovite should be orders of magnitude slower than was previously inferred from in vacuo outgassing experiments, which renders the observation of 40 Ar concentration gradients formed by this process unlikely [45]. Therefore, I think that the possibility that the F-, Rb-, Cs-and Li-rich zones in mica are younger is viable.…”

Section: Pakeagama Lake Pegmatitementioning

confidence: 99%

Do Pegmatites Crystallise Fast? A Perspective from Petrologically-Constrained Isotopic Dating

Popov

2023

Geosciences

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Most recent studies consider the formation of individual pegmatite bodies to be a fast process with estimated crystal growth rates reaching a walloping 10 m/day. This opinion is presumably underpinned by the traditional way of thinking of them as the end products of magmatic fractionation. Indeed, modelling has shown that if a pegmatite-forming substance with a temperature near granitic solidus intrudes into a much colder host rock, as recorded in some outcrops, it must cool rapidly. From here, a conclusion is made that the crystallisation must likewise be rapid. However, this view is challenged by several studies that published isotopic dates supported by petrological characterisation of the analysed materials, which suggested or can be used to suggest that some minerals in pegmatites grew over millions of years. Surprisingly, such in-depth work on the geochronology of individual pegmatite bodies is relatively uncommon, so it is early to make generalisations. Here, I highlight some of the existing evidence with the aim to stimulate further research into the timescales of pegmatite crystallisation, including the use of petrologically constrained isotopic dating.

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Atomistic simulations of 40Ar diffusion in muscovite

Cited by 11 publications

References 125 publications

Cenozoic kinematics of the Wenchuan-Maoxian fault implies crustal stacking rather than channel flow extrusion at the eastern margin of Tibetan plateau (Longmen Shan)

Cenozoic kinematics of the Wenchuan-Maoxian fault implies crustal stacking rather than channel flow extrusion at the eastern margin of Tibetan plateau (Longmen Shan)

40 Ar/ 39 Ar geochronology of crustal deformation

Do Pegmatites Crystallise Fast? A Perspective from Petrologically-Constrained Isotopic Dating

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