Multi-collector 40Ar-39Ar dating of deformation in the Alpi Apuane (northern Apennines)

The Alpi Apuane (northern Apennines) represent a key area for understanding the processes related to the Apennines building and geodynamic evolution of the central Mediterranean, but the timing of tectono-metamorphic events is still debated. ⁴⁰Ar-³⁹Ar in-situ data on rock chips and step-heating data from white-mica separates, supplemented by a detailed structural, textural and chemical characterization down to the microscale, reveal a complex picture that highlights the role of lithology and strain partitioning on the Ar isotope record of white mica in low-grade metamorphic rocks. The significant intrasample scatter of in-situ ages and the variably discordant age spectra from step-heating data, are due to partial re-equilibration of white mica along a deformation path lasting ≥10 Ma, with dates approaching the time of younger events as retrogression becomes more pervasive.

Reference:

Di Vincenzo G., Godard G., Molli G., 2022. Dating low-grade deformation: role of lithology and strain partitioning on Ar isotope records in the Alpi Apuane of northern Apennines (Italy). Tectonics, 41, e2022TC007248. https://doi.org/10.1029/2022TC007248.

For more information: Gianfranco Di Vincenzo, CNR-IGG (gianfranco.divincenzo(at)igg.cnr.it).