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© 2015 Elsevier B.V. The Logrosán Sn-(W) ore deposits in the metallogenic Sn-W province of the European Variscan Belt consist of endo- and exogranitic greisen-type and quartz-cassiterite veins associated with a S-type granite. Mineral characterization, fluid inclusion study, isotope geochemistry and Ar-Ar geochronology have been combined in order to reconstruct the conditions for Sn-(W) mineralization. The endo- and exogranitic mineralization must have been developed in a relatively long-lived system (~308-303Ma), during or soon after the emplacement of the Logrosán related-granite (at ca. 308Ma). The mineralizing fluids are characterized by complex aqueous and volatile (H2O-N2-CO2-CH4-NaCl) fluid inclusions. Microthermometry and Raman analyses indicate that fluid composition evolved from N2-CH4 to N2-rich, followed by CO2-rich fluids, with varying amounts of H2O. The presence of N2 and CH4 suggests the interaction with fluids derived from the nearby metasedimentary host rocks. A model of host-rock interaction, assimilation, and mixing of metamorphic and magmatic fluids, resulting in change of the redox conditions, is proposed for tin deposition. Later sulfide minerals were precipitated as a result of pressure and temperature release., This work was financially supported by the projects CGL2012-32822 (Ministerio de Economía y Competitividad of Spain) and the 910492 (Universidad Complutense de Madrid).

International audience; Fluid inclusions trapped in quartz veins hosted by a leucogneiss from the southern part of the Naxos Metamorphic Core Complex (Attic-Cycladic-Massif, Greece) were studied to determine the evolution of the fluid record of metamorphic rocks during their exhumation across the ductile/brittle transition. Three sets of quartz veins (V-M2, V-BD & V-B) are distinguished. The V-M2 and V-BD are totally or, respectively, partially transposed into the foliation of the leucogneiss. They formed by hydrofracturing alternating with ductile deformation accommodated by crystal-plastic deformation. The V-B is discordant to the foliation and formed by fracturing during exhumation without subsequent ductile transposition. Fluids trapped during crystalplastic deformation comprise two very distinct fluid types, namely a CO2-rich fluid and a high-salinity brine, that are interpreted to represent immiscible fluids generated from metamorphic reactions and the crystallization of magmas respectively. They were initially trapped at approximate to 625 degrees C and 400MPa and then remobilized during subsequent ductile deformation resulting in various degrees of mixing of the two end-members with later trapping conditions of approximate to 350 degrees C and 140MPa. In contrast, brittle microcracks contain aqueous fluids trapped at 250 degrees C and 80MPa. All veins display a similar 13C pointing to carbon that was trapped at depth and then preserved in the fluid inclusions throughout the exhumation history. In contrast, the D signature is marked by a drastic difference between (i) V-M2 and V-BD veins that are dominated by carbonic, aqueous-carbonic and high-salinity fluids of metamorphic and magmatic origin characterized by D between 56 parts per thousand and 66 parts per thousand, and (ii) V-B veins that are dominated by aqueous fluids of meteoric origin characterized by D between 40 parts per thousand and 46 parts per thousand. The retrograde PT pathway implies that the brittle/ductile transition separates two structurally, chemically and thermally distinct fluid reservoirs, namely (i) the ductile crust into which fluids originating from crystallizing magmas and fluids in equilibrium with metamorphic rocks circulate through a geothermal gradient of 30 degrees C km1 at lithostatic pressure, and (ii) the brittle upper crust through which meteoric fluids percolate through a high geothermal gradient of 55 degrees C km1 at hydrostatic pressure.

International audience; High salinity brines are commonly sampled as fluid inclusions in close paragenetic relationship with unconformity-related U mineralizations in the Proterozoic Athabasca Basin. The large range of brine composition results from the mixing of two end-members (NaCl-rich and CaCl2-rich) during or after maximum burial (T from 120 to 180°C) [1]. Here, we address the question of the origin of these brines and their possible interactions with basin and basement lithologies. Chorinities of 5-7 molal, coupled with Cl/Br ratios of 100-400 and negative ä37Cl values, are unambiguously in favour ofa common dominant evaporated seawater origin for both brines, typical of primary brines having past the point of halite precipitation. Such brines either have immediately percolated through the sedimentary pile, or alternatively have been trapped in the evaporitic formation and were expelled afterwards during compaction events. ä18O values of inclusions-hosting quartz and dolomites are compatible with evolved deep basinal brines.The CaCl2-rich brines are thought to result from strong interactions with basement lithologies where they have uptaken uranium, as shown by the very high content detected by LA-ICP-MS. The range of 87Sr/86Sr ratios of inclusionshosting dolomite veins suggests a mixed origin, between a marine origin and a more radiogenic component typical of basement lithologies. D/H values of brines, coupled with ä13C values of dissolved CO2 argue for interactions with organicmatter and D-depleted materials. The isotopic trends mayindicate the involvement of C-rich components in the waterrock processes in relation with the U mineralization.

International audience; Au and W-Sn mineralization of the Schistose Domain of Galicia-Trás-os-Montes are spatially related to late hercynian granites. The Bruès (Au) and the Mina Soriana W-(Sn) deposits are studied. Both show some similarities and are assumed to form in the same tectonic and metamorphic context, on top of the granites. The role of the granite as a source for mineralizing fluids and rheological control for vein emplacement is re-adressed and discussed.

The intracontinental geothermal field of Larderello (Tuscany, Italy) is a vapour-dominated system, which has been exploited for electricity production throughout this Century. At Lardereil0, studies on hydrothermal mineral assemblages and related fluid inclusions evidenced the presence of several fluid types of different sources and a complex evolution of the geothermal system, from early stage circulation, related to granite emplacement, to present-day condition (Valori et al., 1992; Cathelineau et al., 1994). In this study we measured N2/Ar ratio and the isotopic compositions of noble gases and carbon of CO2 extracted by undervacuum crushing of fluid inclusions in order to: 1) define the origin of the palaeogeothermal fluids, 2) compare noble gas and CO2 isotopic compositions of the fluid trapped in the inclusions with present-day discharged fluid and evaluate if the source of these fluids has been changed with time. The stratigraphy of the deep geothermal wells (up to 4.5 km below the ground level, b.g.l.) schematically consists of (from top to bottom): 1) a cover of siliciclastic sediments, carbonatic rocks, evaporite and ophiolite rocks (Late Triassic to Pliocene), 2) a complex of tectonic slices which include the lower formation of the sedimentary rocks and the uppermost part of the metamorphic basement, 3) a metamorphic basement (Palaeozoic), consisting of phyllitic-quartzitic rocks, micaschists and gneisses. The deepest wells at Larderello have also encountered contact metamorphic rocks and granite dykes and intrusion with ages between 1.3 and 3.8 Ma. Geophysical data suggest that a large intrusion is present below the Larderello area; the geothermal activity can be related to the presence of this intrusion. The productive horizons were found in Triassic carbonate and anhydrite formations (shallow reservoir) of the upper units and in some permeable levels of the Palaeozoic metamorphic basement (deep reservoir).

The geometry of the ore fluid migration was investigated in the (W-Sn) mineralizated granites of the Spanish Central System. Based on microthermometry, Raman microprobe and textural relationships, six types of fluid inclusions have been distinguished: 1) Magmatic hypersaline aqueous fluid represented by Lw-s inclusions. 2) Metamorphic aquo-carbonic fluids represented as different types of fluid inclusions: (i) H20 - C02-(CH4) fluids represented by Vc-w three phase inclusions at room temperature; (ii) H 20 - C 0 2-CH4 fluids showing two-phase at room temperature with a low density volatile phase displaying a large variation of the CH4/C02 ratio; (iii) H20-CH4 fluids represented by Lw-m two-phase inclusions with a volatile phase entirely dominated by CH4.3) Aqueous fluid sare shown by (iv) Lw1 and (v) Lw2 two phase in elusions with low to moderate salinity. Fluid trapping occurred in the granites by means of a complex succession of opening and reopening of microfracture network. NE-SW ductile-brittle cracks contains quartz-wolframite thus connected with FIP bearing aqueous-carbonic fluids. A later drop in C02 es recorded in N140°-150°E, N 100°-110°E, N-S and E-W. A latest fluid is represented by aqueous fluids crosscutting the precedent fluid inclusions planes

The geometry of the ore fluid migration was investigated in the (W-Sn) mineralizated granites of the Spanish Central System. Based on microthermometry, Raman microprobe and textural relationships, six types of fluid inclusions have been distinguished: 1) Magmatic hypersaline aqueous fluid represented by Lw-s inclusions. 2) Metamorphic aquo-carbonic fluids represented as different types of fluid inclusions: (i) H20 - C02-(CH4) fluids represented by Vc-w three phase inclusions at room temperature; (ii) H 20 - C 0 2-CH4 fluids showing two-phase at room temperature with a low density volatile phase displaying a large variation of the CH4/C02 ratio; (iii) H20-CH4 fluids represented by Lw-m two-phase inclusions with a volatile phase entirely dominated by CH4.3) Aqueous fluid sare shown by (iv) Lw1 and (v) Lw2 two phase in elusions with low to moderate salinity. Fluid trapping occurred in the granites by means of a complex succession of opening and reopening of microfracture network. NE-SW ductile-brittle cracks contains quartz-wolframite thus connected with FIP bearing aqueous-carbonic fluids. A later drop in C02 es recorded in N140°-150°E, N 100°-110°E, N-S and E-W. A latest fluid is represented by aqueous fluids crosscutting the precedent fluid inclusions planes