Fault inversion may lead to significant obliteration of earlier tectonic structures, thus preventing the straightforward interpretation of the complete kinematics and deformation history of faults. We adopt a multidisciplinary approach to: (1) reconstruct the tectonic evolution through space and in time of the extensionally-inverted Mt. Tancia Thrust (Central Apennines, Italy); (2) understand the deformation mechanisms and the transition and reactivation of compressional structures during negative tectonic inversion; and (3) constrain the origin of fluids involved during tectonic processes. To this end, we combined: (1) detailed geological mapping and multiscale structural analysis; (2) illite-smectite paleothermal indicators; (3) C, O, and clumped isotopes on calcite mineralizations and (4) K–Ar dating of authigenic and/or syn-kinematic illite from the Mt. Tancia Thrust fault rocks. We show that shortening occurred between ~9 and ~7 Ma, during possibly multiple events of fluid overpressure and shear rupturing involving fluids entrapped over long term within the host rocks. Post-compressive tectonic inversion occurred at ~3 Ma under fluid pressure fluctuations during shear events with an input of meteoric-derived fluids. Tectonic inversion is spatially confined within the first few metres below the thrust surface in a volume dominated by the partial overprinting, folding, transposition, and re-utilization of the earlier compressional fabric.
Architecture and evolution of an extensionally-inverted thrust (Mt. Tancia Thrust, Central Apennines) : Geological, structural, geochemical, and K–Ar geochronological constraints / M. Curzi, L. Aldega, S.M. Bernasconi, F. Berra, A. Billi, C. Boschi, S. Franchini, R. Van der Lelij, G. Viola, E. Carminati. - In: JOURNAL OF STRUCTURAL GEOLOGY. - ISSN 0191-8141. - 136:(2020 Jul), pp. 104059.1-104059.23. [10.1016/j.jsg.2020.104059]
Architecture and evolution of an extensionally-inverted thrust (Mt. Tancia Thrust, Central Apennines) : Geological, structural, geochemical, and K–Ar geochronological constraints
F. Berra;
2020
Abstract
Fault inversion may lead to significant obliteration of earlier tectonic structures, thus preventing the straightforward interpretation of the complete kinematics and deformation history of faults. We adopt a multidisciplinary approach to: (1) reconstruct the tectonic evolution through space and in time of the extensionally-inverted Mt. Tancia Thrust (Central Apennines, Italy); (2) understand the deformation mechanisms and the transition and reactivation of compressional structures during negative tectonic inversion; and (3) constrain the origin of fluids involved during tectonic processes. To this end, we combined: (1) detailed geological mapping and multiscale structural analysis; (2) illite-smectite paleothermal indicators; (3) C, O, and clumped isotopes on calcite mineralizations and (4) K–Ar dating of authigenic and/or syn-kinematic illite from the Mt. Tancia Thrust fault rocks. We show that shortening occurred between ~9 and ~7 Ma, during possibly multiple events of fluid overpressure and shear rupturing involving fluids entrapped over long term within the host rocks. Post-compressive tectonic inversion occurred at ~3 Ma under fluid pressure fluctuations during shear events with an input of meteoric-derived fluids. Tectonic inversion is spatially confined within the first few metres below the thrust surface in a volume dominated by the partial overprinting, folding, transposition, and re-utilization of the earlier compressional fabric.File | Dimensione | Formato | |
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