The central Apennines are a fold-thrust belt currently affected by post-orogenic ex-tensional seismicity. To constrain the influ-ence that the inherited thrust-related struc-tures exert on the present seismic behavior of the belt, we provide the high-resolution structural and hydraulic characterization of one of the most external exposed thrust fault systems of the central Apennines, the Sibil-lini Mts. Thrust Front (STF). We integrate structural mapping, multiscale structural analysis, and in situ air permeability on the brittle structural facies of the thrust zone. We also performed K-Ar dating of selected fault rocks to better constrain structural in-heritance. The STF is defined by a complex, similar to 300-m-thick deformation zone involving Meso-Cenozoic marl and limestone that re-sults from the accommodation of both seis-mic and aseismic slip during shortening. Permeability measurements indicate that the low permeability (10-2 divided by 10-3 D) of the marly rich host rock diminishes within the thrust zone, where the principal slip surfaces and associated S-C structures represent efficient hydraulic barriers (permeability down to similar to 3 x 10-10 D) to sub-vertical fluid flow. Field data and K-Ar dating indicate that the STF began its evolution ca. 7 Ma (early Messin-ian). We suggest that the studied thrust zone may represent a barrier for the upward migration of deep fluids at the hypocentral depth of present-day extensional earth-quakes. We also speculate on the influence that similar deformation zones may have at depth on the overall regional seismotectonic pattern by causing transient fluid overpres-sures and, possibly, triggering cyclic exten-sional earthquakes on normal faults prone to slip while crosscutting the earlier thrust zones (as per a classic fault valve behavior). This mechanism may have controlled the ori-gin of the 2016-2017 central Apennines dev-astating earthquakes.

Architecture and permeability structure of the Sibillini Mts. Thrust and influence upon recent, extension-related seismicity in the central Apennines (Italy) through fault-valve behavior / Curzi, M; Cipriani, A; Aldega, L; Billi, A; Carminati, E; van der Lelij, R; Vignaroli, G; Viola, G. - In: GEOLOGICAL SOCIETY OF AMERICA BULLETIN. - ISSN 0016-7606. - (2023). [10.1130/B36616.1]

Architecture and permeability structure of the Sibillini Mts. Thrust and influence upon recent, extension-related seismicity in the central Apennines (Italy) through fault-valve behavior

Curzi, M
;
Cipriani, A;Aldega, L;Billi, A;Carminati, E;Viola, G
2023

Abstract

The central Apennines are a fold-thrust belt currently affected by post-orogenic ex-tensional seismicity. To constrain the influ-ence that the inherited thrust-related struc-tures exert on the present seismic behavior of the belt, we provide the high-resolution structural and hydraulic characterization of one of the most external exposed thrust fault systems of the central Apennines, the Sibil-lini Mts. Thrust Front (STF). We integrate structural mapping, multiscale structural analysis, and in situ air permeability on the brittle structural facies of the thrust zone. We also performed K-Ar dating of selected fault rocks to better constrain structural in-heritance. The STF is defined by a complex, similar to 300-m-thick deformation zone involving Meso-Cenozoic marl and limestone that re-sults from the accommodation of both seis-mic and aseismic slip during shortening. Permeability measurements indicate that the low permeability (10-2 divided by 10-3 D) of the marly rich host rock diminishes within the thrust zone, where the principal slip surfaces and associated S-C structures represent efficient hydraulic barriers (permeability down to similar to 3 x 10-10 D) to sub-vertical fluid flow. Field data and K-Ar dating indicate that the STF began its evolution ca. 7 Ma (early Messin-ian). We suggest that the studied thrust zone may represent a barrier for the upward migration of deep fluids at the hypocentral depth of present-day extensional earth-quakes. We also speculate on the influence that similar deformation zones may have at depth on the overall regional seismotectonic pattern by causing transient fluid overpres-sures and, possibly, triggering cyclic exten-sional earthquakes on normal faults prone to slip while crosscutting the earlier thrust zones (as per a classic fault valve behavior). This mechanism may have controlled the ori-gin of the 2016-2017 central Apennines dev-astating earthquakes.
2023
fault architecture; permeability; Apennines
01 Pubblicazione su rivista::01a Articolo in rivista
Architecture and permeability structure of the Sibillini Mts. Thrust and influence upon recent, extension-related seismicity in the central Apennines (Italy) through fault-valve behavior / Curzi, M; Cipriani, A; Aldega, L; Billi, A; Carminati, E; van der Lelij, R; Vignaroli, G; Viola, G. - In: GEOLOGICAL SOCIETY OF AMERICA BULLETIN. - ISSN 0016-7606. - (2023). [10.1130/B36616.1]
File allegati a questo prodotto
File Dimensione Formato  
Curzi_Architecture_2023 .pdf

accesso aperto

Tipologia: Versione editoriale (versione pubblicata con il layout dell'editore)
Licenza: Creative commons
Dimensione 19.71 MB
Formato Adobe PDF
19.71 MB Adobe PDF

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1679845
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? 6
social impact