Publication Date:
2023-02-02
Description:
We analyzed from meso-to microscale the chemical interaction (e.g., bleaching) between deep fluids and carbonate
rocks in pelagic limestones exposed along the seismically active Gubbio normal fault (Northern Apennines),
exhumed from ca. 2 km depth. Bleaching is enhanced by the exploitation of inherited stylolitic seams by
fluids and is favored by the progressive leaching and mobilization of primary components (i.e., Ca, Fe, Pb, and
Cu) and the precipitation of authigenic baryte due to temperature and/or redox potential contrast.
Analysis of fluid inclusions trapped in calcite veins in the damage zone precipitated from a H2O–NaCl-bearing
fluid(s), with low salinity (1.22–2.57 wt%NaCleq) and a range of trapping temperature between 107 ◦C and 185
◦C, higher than the host rock peak T conditions. Analysis of fluid inclusions and noble gases from syn-kinematic
calcite and mineralogy of altered rocks suggests a mixed contribution between crustal-derived fluids with
diagenetic fluids containing sulphates and CO2. We speculate that bleaching is a by-product of the circulation of
such aggressive fluids with mixed contributions, likely mobilized during seismic event(s) and injected into the
damage zone at shallow depths. Such processes, affecting the chemical-physical properties of limestones, are
generally underestimated and should be considered when modelling hydraulic connectivity in fractured carbonate
reservoirs.
Description:
Published
Description:
104668
Description:
9T. Geochimica dei fluidi applicata allo studio e al monitoraggio di aree sismiche
Description:
JCR Journal
Keywords:
fluids
;
eartquakes
;
Gubbio Fault
;
noble gases
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
