From deep to shallow fluid reservoirs: evolution of fluid sources during exhumation of the Sierra Almagrera, Betic Cordillera, Spain

Abstract

Palaeo-fluids trapped in quartz and siderite-barite veins hosted by graphitic schists recorded the fluid and metal transfers during the Neogene exhumation of the Sierra Almagrera Metamorphic Core Complex. First quartz veins registered the ductile then brittle-ductile extensional shearing. The reservoir at that time was wetted by high-salinity fluids with a low density volatile phase resulting from the dissolved Triassic evaporites. Low salinity fluids occurred during the exhumation within the brittle domain as revealed by transgranular fluid inclusion planes affecting previous veins. This suggests an opening of the system and the penetration of surficial fluids from uplifted ranges during Serravalian to early Tortonian times.Transcurrent tectonics generated marine basins since late Tortonian. At depth quartz veins discordant to the foliation were associated to hematite indicating oxydizing conditions. A stop of the low-saline record is revealed by high-salinity Fe-rich fluids issued from the underlying metamorphic reservoir. The Messinian ongoing activity of the sinistral Trans-Alboran tectonovolcanic trend led to the formation of ore deposits.Reducing conditions and Fe-rich fluid led to the formation of siderite and pyrite. The subsequent formation of galena and barite under oxydizing conditions has been related to a probable increase of temperature. A higher salinity and the Cl/Br ratio indicate another source of secondary brine issued from dissolved Messinian evaporites as confirmed by δ This is a PREPRINT version (pre-refereeing) of the paper: Dyja, V., Hibsch, C., Tarantola, A., Cathelineau M., Boiron M.C., Marignac C, Bartier, D., Carrillo-Rosúa, J., Morales-Ruano, S., Boulvais, P. (2015). From deep to shallow fluid reservoirs: evolution of fluid sources during exhumation of the Sierra

CO 2 flow during orogenic gravitational collapse: Syntectonic decarbonation and fluid mixing at the ductile-brittle transition (Lavrion, Greece)

“…The fluid record of an exhumed metamorphic rock shows first trapping of metamorphic and/or magmatic fluids associated with ductile deformation and then entrapment of surface-derived fluids along fractures illustrating the transition from the deep ductile reservoir to the upper crustal brittle reservoir (Siebenaller et al, 2013;Dyja et al, 2016). Isotopic evidences suggest that superficial fluids can penetrate the crust down to the ductile crust along low-angle or high angle faults that are rooted into low-angle normal faults (e.g.…”

“…Isotopic evidences suggest that superficial fluids can penetrate the crust down to the ductile crust along low-angle or high angle faults that are rooted into low-angle normal faults (e.g. Kerrich et al, 1984;Wickham et al, 1993;Morrison, 1994;Upton et al, 1995;Ingebritsen and Manning, 1999;Famin et al, 2004;Famin et al, 2005;Siebenaller et al, 2013;Menzies et al, 2014;Dyja et al, 2016).…”

“…Below the DBT, fluids of the deep crust reservoir are confined under lithostatic conditions A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 5 and their redistribution is intimately linked to intracrystalline deformation (Siebenaller et al, 2016) whereas, above the DBT, fluids of the upper crust reservoir are submitted to alternating lithostatic and hydrostatic conditions (Morrison and Anderson, 1998;Famin et al, 2005;Siebenaller et al, 2013;Dyja et al 2016). As such, because the DBT zone is a place of change in the pressure regime and of fluid mixing, it appears as a strategic target to decipher fluidrock interactions and exchanges between fluids reservoirs.…”

A comparison of isotope ratio mass spectrometry and cavity ring‐down spectroscopy techniques for isotope analysis of fluid inclusion water

“…6,7,34 Furthermore, the technique has successfully been applied on hydrothermal vein mineralization to gain insight into subsurface fluid flow dynamics. [18][19][20]35 As a more cost-efficient alternative, fluid inclusion isotope ratios may also be measured on an IRMS instrument using an off-line extraction method. 36 Since the beginning of the 2010s, new online setups have been developed using cavity ring-down spectroscopy (CRDS), which was already an established technique for the accurate isotope analysis of water samples.…”

The origin of large gypsum crystals in the Geode of Pulpí (Almería, Spain)

“…In Mina Rica, the first and main mineralization stage occurred after the Serravallian deformation (Sanz de Galdeano, 1990) and before 5.6 Ma. This upper time constraint, corresponding to the sea-level fall of the Messinian crisis, is based on the limit found by Dyja et al (2015) for similar Fe-Ba mineralizations at Almagrera-Herrerias (Fig. 1).…”