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Earth sciences

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Alpine deformation and (super 40)Ar/(super 39)Ar geochronology of synkinematic white mica in the Siviez-Mischabel Nappe, western Pennine Alps, Switzerland

Article Abstract:

A (super 40)Ar/(super 39)Ar analysis was performed on synkinematic white mica samples from the Siviez-Mischabel Nappe, western Swiss Alps, to determine the timing of the nappe's exhumation and deformation. It was found that the primary foilation from Permo-Triassic covered sediments by nucleation, growth and rigid rotation of mica grains during noncoaxial Alpine deformation. The result suggests that the Siviez-Mischabel Nappe occurred and developed foilation during a five m.y. period.

Surfaces, Deformation of, Surface deformation, Geology, Stratigraphic, Stratigraphy, Muscovite, Nappes (Geology), Nappes, Triassic period

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Radiometric age constraints on mineral growth, metamorphism, and tectonism of the Gummfluh Klippe, Brianconnais domain of the Prealpes, Switzerland

Article Abstract:

An analysis of white micas from the Gummfluh Klippe in Switzerland is presented. The klippe is part of the Brianconnais domain of the country's Prealpes and is composed of Mesozoic to early Tertiary carbonate rocks. White mica separates indicate ages ranging from 57 to 103 Ma based on K/Ar and Rb/Sr techniques. In addition, sample characterization shows the presence of coarser grained and fine grained white mica populations.

Switzerland, Minerals, Minerals (Geology), Radioactive dating, Radiometric dating

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Dating incipient metamorphism using 40Ar/39Ar geochronology and XRD modeling: a case study from the Swiss Alps

Article Abstract:

X-ray diffraction modeling and 40Ar/39Ar geochronology were used to study samples of metamorphosed neoformed illite of the Couches Rouges that were collected at different locations within the Swiss Alps. Results revealed an extrapolated age of 27 Ma for 100% neoformed dioctahedral phyllosilicates. This age represents the time of incipient metamorphism of the Couches Rouges stratigraphic unit.

Mica

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