Cenozoic deformation in the Tauern Window (Eastern Alps, Austria) constrained by in-situ Th-Pb dating of fissure monazite

Abstract

Abstract. Thorium-Pb crystallization ages of hydrothermal monazites from the western, central and eastern Tauern Window provide new insights into Cenozoic tectonic evolution of the Tauern metamorphic dome. Growth domain crystallization ages range from 22.3 ± 0.6 Ma to 7.7 ± 0.9 Ma. Three major periods of monazite growth are recorded between ~ 22–19 (peak at 21 Ma), 19–15 (major peak at 17 Ma) and 13–8 Ma (major peaks at 12, 10 and 8 Ma), respectively interpreted to be related to prevailing N-S shortening, in association with E-W extension, beginning strike-slip movements, and reactivation of strike-slip faulting. Fissure monazite ages largely overlap with zircon and apatite fission tracks data. Besides tracking the thermal evolution of the Tauern dome, monazite dates reflect episodic tectonic movement along major shear zones that took place during the formation of the dome. Geochronological and structural data from the Pfitschtal area in the western Tauern Window show the existence of two cleft generations separated in time by 4 Ma and related to strike-slip to oblique-slip faulting. Moreover, these two phases overprint earlier phases of fissure formation.

Unravelling the Hydration History of an Inverted Passive Continental Margin Using Epidote U–Pb Geochronology and Pb–Sr–O–H Isotope Geochemistry

“…To reconstruct fluid circulation in crustal rocks, numerous studies use trace element, isotope and geochronological data of hydrothermal structures such as veins or hydrothermally deformed rocks (e.g., Dempster, 1986;Dusséaux et al, 2022;Grambling et al, 2022;Hofmann et al, 2004;Incerpi et al, 2017Incerpi et al, , 2018Incerpi et al, , 2020Kralik et al, 1992;Manatschal et al, 2000;Marquer and Burkhard, 1992;Marquer and Peucat, 1994;Mulch et al, 2006;Peverelli et al, 2022aPeverelli et al, , 2022bPinto et al, 2015;Ricchi et al, 2019aRicchi et al, , 2019b. One advantage of targeting veinfilling minerals for this purpose is that they precipitate directly from the mineralizing fluid, whose geochemical and isotopic characteristics are recorded and can be used to investigate fluid pathways (e.g., Bons et al, 2012;Elburg et al, 2002;Pettke et al, 2000).…”