Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/11914
Authors: Smeraglia, Luca* 
Bernasconi, Stefano* 
Berra, Fabrizio* 
Billi, Andrea* 
Boschi, Chiara* 
Caracausi, Antonio* 
Carminati, Eugenio* 
Castorina, Francesca* 
Doglioni, Carlo* 
Italiano, Francesco* 
Rizzo, Andrea Luca* 
Tonguç Uysal, I.* 
Zhao, Jian-xin* 
Title: Crustal-scale fluid circulation and co-seismic shallow comb-veining along the longest normal fault of the central Apennines, Italy
Issue Date: 2018
Series/Report no.: /498 (2018)
DOI: 10.1016/j.epsl.2018.06.013
URI: http://hdl.handle.net/2122/11914
Abstract: The extensional Val Roveto Fault, which is the longest exhumed potentially-seismogenic structure of central Apennines, Italy, is examined to constrain earthquake-related fluid circulation and fluid sources within shallow carbonate-hosted faults. The study focuses on fault-related comb and slip-parallel veins that are calcite-filled and cut through the principal surface of the Val Roveto Fault. We observe multiple crack-and-seal events characterized by several veining episodes, probably related to different slip increments along the fault plane. We show that vein calcite precipitated in Late Pleistocene time below the present-day outcrop level at a maximum depth of ∼350 m and temperatures between 32 and 64◦C from meteoric-derived fluids modified by reactions with crustal rocks and with a mantle contribution (up to ∼39%). The observed warm temperatures are not compatible with a shallow (≤∼350m) precipitation depth, which, in this region, is dominated by circulation of cold meteoric water and/or shallow groundwater. Based on structural–geochemical data, we propose that deep-seated crust–mantle-derived warm fluids were squeezed upward during earthquakes and were hence responsible for calcite precipitation at shallow depths in co-seismic comb and slip-parallel fractures. As comb-and slip-parallel veins are rather common, particularly along seismogenic extensional faults, we suggest that further studies are necessary to test whether these veins are often of co-seismic origin. If so, they may become a unique and irreplaceable tool to unravel the seismic history of hazardous active faults.
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