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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 (≤∼350 m) 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.

A new discovery of carbonatites at Pianciano, Ficoreto and Forcinelle in the Roman Region demonstrates that Italian carbonatites are not just isolated, mantle xenoliths-bearing, primitive diatremic rocks but also evolved subtype fluor-calciocarbonatite (F ~ 10 wt%) associated with fluor ore (F ~ 30 wt%). New data constrain a multi-stage petrogenetic process, 1-orthomagmatic, 2-carbothermal, 3-hydrothermal. Petrography and geochemistry are conducive to processes of immiscibility and decarbonation, rather than assimilation and crystal fractionation. A CO2-rich, ultra-alkaline magma is inferred to produce immiscible melilite leucitite and carbonatite melts, at lithospheric mantle depths. At the crustal level and in the presence of massive CO2 exsolution, decarbonation reactions may be the dominant processes. Decarbonation consumes dolomite and produces calcite and periclase, which, in turn, react with silica to produce forsterite and Ca silicates (monticellite, melilite, andradite). Under carbothermal conditions, carbonate breakdown releases Sr, Ba and LREE; F and S become concentrated in residual fluids, allowing precipitation of fluorite and barite, as well as celestine and anhydrite. Fluor-calciocarbonatite is the best candidate to exsolve fluids able to deposit fluor ore, which has a smaller volume. At the hydrothermal stage, REE concentration and temperature dropping allow the formation of LREEF2+ and LREECO3+ ligands, which control the precipitation of interstitial LREE fluorcarbonate and silicates: (bastnäsite-(Ce), Ce(CO3)F and britholite-(Ce), (Ce,Ca)5(SiO4,PO4)3(OH,F). Vanadates such as wakefieldite-(Ce), CeVO4, vanadinite, Pb5(VO4)3Cl and coronadite Pb(Mn4+ 6 Mn3+ 2)O16 characterise the matrix. At temperatures of ≤100 °C analcime, halloysite, quartz, barren calcite, and zeolites (K-Ca) precipitate in expansion fractures, veins and dyke aureoles. © 2019 The Authors

The Late Cretaceous-Quaternary Cameroon Volcanic Line (CVL) is a 1600km long chain of volcanoes that straddles the continent-ocean boundary and extends from the Gulf of Guinea to the interior of the African continent. The magmatic activity started at 70Ma and has continued until the present. The products of this magmatic activity are distinctive in terms of petrology and isotope geochemistry, the variety of volcanic rocks ranging from ultrabasic, alkaline to sub-alkaline lavas to highly evolved alkaline lavas with isotopic compositions indicating complex combinations of both sub-lithospheric (HIMU, EM, DMM) and lithospheric components (sub-continental lithospheric mantle and crust). We conducted a petrological and geochemical study of a set of volcanic rocks, sampled from the rim and interior of the Miocene Mt Bambouto caldera, one of the 12 main volcanic centres of the CVL. The rocks were analysed for their whole-rock major and trace element contents, 40Ar/39Ar ages and whole-rock Sr-Nd-Pb-Os isotopic compositions. Phonolites and quartz-trachytes of the Mt Bambouto caldera are derived by fractional crystallization of highly alkaline and moderately alkaline parental basic magmas, respectively. Assimilation of the shallow crust has affected both alkaline and subalkaline magmas, suggesting that the petrogenesis of the differentiated rocks cannot be explained by crustal contamination alone. Only minor amounts (usually less than 5%) of assimilation of upper crustal silicic rocks from the local Pan-African basement are required to produce the most differentiated compositions. The rocks with the highest crustal contribution are Q-normative trachytes from peripheral cones, as well as one Ne-trachyte. Mt Bambouto basic-ultrabasic rocks, including basanites and alkali-basalts with high 187Os/188Osi, might have experienced some crustal contamination, but it must have been a limited process. Some Mt Bambouto ultrabasic to basic rocks show large ion lithophile element enrichmen

© 2014 Elsevier B.V. The living euryhaline species Cyprideis torosa (Jones) undergoes morphometric variations in size, noding and sieve-pore shape linked to the environmental salinity. In particular it is known that salinity values around 8-9 psu represent the osmoregulation threshold and also the turning point between smaller and greater valve dimensions and prevailingly noded against un-noded valves. The variation of the percentage of round-, elongate- and irregular-shaped sieve-pores on the valves has shown an empiric logarithmic correlation with the water salinity from 0 to 100 psu. Due to this ecologically cued polymorphism, C. torosa represents an invaluable paleosalinometer for the Quaternary brackish basins. In this paperwe attempt to verifywhether the ecophenotypical behavior of the post-evaporiticMessinian species Cyprideis agrigentina Decima was comparablewith that of Cyprideis torosa. To reach this goal, threemorphometric characters have been analyzed: 1) size variability; 2) noding and ornamentation; and 3) variability of the percentage of the sieve-pore shapes. The paleoenvironmental interpretation was made using synecological and geochemical approaches [stable isotopes, trace elements, Sr-isotopes and natural radioactivity (NRD)]. For this study, the 250 m-thick Messinian Lago-Mare succession of Eraclea Minoa (Agrigento, Sicily) was chosen for the presence ofmonotypic assemblagesmade only by C. agrigentina for around 70mof thickness. The results of the morphometric analyses showed that: 1) size variations are not related to the salinity changes recognized both from synecological and geochemical analyses; 2) no noded specimens have been recovered along the Section; 3) the salinities calculated on the basis of the percentage of the sieve-pore shape are not correlated with the salinities inferred from the synecological and geochemical analyses. Thus, in this paper we conclude that Cyprideis agrigentina cannot be considered a paleosalinometer for the Mess

The Jbel Tirremi fluorite-barite sulfide deposit in northeastern Morocco is hosted in a Jurassic-aged structurally high carbonate platform known as the Jbel Tirremi dome. The host rocks consist of unmetamorphosed, flat-lying early Jurassic dolomitized limestones, locally intruded by Eocene lamprophyre dikes. The orebodies consist mostly of fluorite and barite, and occur as open-space fillings and partial to massive replacement of the enclosing medium- to coarse-grained dolomitized limestones. The ore mineralogy is dominated by fluorite of different colors and habits, barite, and, to a lesser extent, sulfides. Rare earth element compositions along with fluid inclusion, halogen and isotopic data suggest that the fluorite barite mineralization and the spatially associated Eocene alkaline magmatism are petrogenetically unrelated, pointing instead to the regional circulation of hydrothermal basinal brines mixed to various degrees with meteoric water in a dominantly closed rock-buffered system at progressively higher temperatures and fluid/rock ratios. In this respect, fluid inclusion microthermometric measurements show that the ore-bearing hydrothermal system developed in two separate stages of fluorite-barite mineralization, as also revealed by isotopic data. Both stages precipitated from saline fluids at shallow crustal levels (i.e., <5 km), and were related, in varying degrees, to different stages of basin evolution and salt dome growth (salt mobilization and mineralization). During the first stage, the ore fluid was a highly saline aqueous brine with a total salinity up to 44.2 wt % NaCl + KCl equiv, at temperatures >= 82 degrees C and possibly up to 218 degrees C, whereas in the second stage the mineralizing fluid had a similar temperature range, but lower salinities (similar to 20-10 wt % NaCl equiv). The recorded high salinities are interpreted to represent the involvement of a mixture of halite dissolution water and evaporated seawater component. Oxygen (delta O

The Jbel Tirremi fluorite-barite sulfide deposit in northeastern Morocco is hosted in a Jurassic-aged structurally high carbonate platform known as the Jbel Tirremi dome. The host rocks consist of unmetamorphosed, flat-lying early Jurassic dolomitized limestones, locally intruded by Eocene lamprophyre dikes. The orebodies consist mostly of fluorite and barite, and occur as open-space fillings and partial to massive replacement of the enclosing medium- to coarse-grained dolomitized limestones. The ore mineralogy is dominated by fluorite of different colors and habits, barite, and, to a lesser extent, sulfides. Rare earth element compositions along with fluid inclusion, halogen and isotopic data suggest that the fluorite barite mineralization and the spatially associated Eocene alkaline magmatism are petrogenetically unrelated, pointing instead to the regional circulation of hydrothermal basinal brines mixed to various degrees with meteoric water in a dominantly closed rock-buffered system at progressively higher temperatures and fluid/rock ratios. In this respect, fluid inclusion microthermometric measurements show that the ore-bearing hydrothermal system developed in two separate stages of fluorite-barite mineralization, as also revealed by isotopic data. Both stages precipitated from saline fluids at shallow crustal levels (i.e., <5 km), and were related, in varying degrees, to different stages of basin evolution and salt dome growth (salt mobilization and mineralization). During the first stage, the ore fluid was a highly saline aqueous brine with a total salinity up to 44.2 wt % NaCl + KCl equiv, at temperatures >= 82 degrees C and possibly up to 218 degrees C, whereas in the second stage the mineralizing fluid had a similar temperature range, but lower salinities (similar to 20-10 wt % NaCl equiv). The recorded high salinities are interpreted to represent the involvement of a mixture of halite dissolution water and evaporated seawater component. Oxygen (delta O

Late Miocene brackish ostracods and molluscs collected in three Italian basins show noticeable differences in their taxonomic composition, despite their capability of dispersing across wide geographic areas. In the Venetian-Friulian Basin (northern Italy), the upper Tortonian sediments contain oligotypic ostracod assemblages including Hemicyprideis dacica dacica, Hemicytheria pejinovicensis, and Loxoconcha cf. L. josephi and few gastropods referable to Planorbidae and Stenothyroides, which are typical of the central Paratethys. In central Italy, the brackish ostracods and molluscs recovered from upper Tortonian-lower Messinian deposits from four Tuscan basins (Volterra-Radicondoli, Velona, Baccinello-Cinigiano, and Valdelsa) display high affinity at a generic level but strong endemicity at a specific level. At Cessaniti (southern Italy), the upper Tortonian unit contains oligotypic brackish ostracods and molluscs: Mediocytherideis (Sylvestra) posterobursa, Cyprideis ruggierii, Loxoconcha cf. L. biformata, and Zonocypris membranae quadricella characterise the ostracod fauna, while Granulolabium bicinctum and Hydrobia frauenfeldi are the dominant molluscs. The recovered ostracods have a strong affinity with brackish species from central and eastern Palaeo-Mediterranean areas, whereas the molluscs present a Paratethyan origin. Despite the fact that the basins are all brackish and partly coeval, the systematics of these assemblages highlights the absence of common species among the three studied areas. Geochemical analyses (stable isotopes and trace elements) are performed on ostracods, and 87Sr/ 86Sr ratios are established in molluscs and echinoids. The results suggest brackish environments with different compositions and origins of solutes in the three different areas. The Tuscan basins are characterised by brackish waters, with NaCl-enriched waters coming from aquifers of Triassic evaporite bedrock. The brackish deposits of the Venetian-Friulian Basin and Cessaniti a

The final conclusions of a multidisciplinary study of Earth and Soil Sciences, carried out in the frame of Prin 2007 are presented. The study has dealt with a variety of natural materials, encompassing soils, waters, atmospheric depositions, the vegetation and the bottom sediments of a coastal lagoon, in the territory north of Ravenna, characterized by important agricultural and industrial activities. In particular, by chemical and isotopic methodologies and pedological survey, it has been studied the ecosystem of the San Vitale Pinewood and the Lagoon of Pialassa Baiona, both constituting the southernmost part of the Po river delta Park. The results obtained have shown that the Pinewood is affected by major salinization processes induced by local subsidence and concerning underground water and soils. This jeopardizes the vegetation's health, in particular, the pine trees that are the main characteristic species. Moreover, the proximity of the industrial zone of Ravenna to the Pinewood represents another threat to the environment, as it is a major pollution source by release of particulate matter with stacks. Therefore, potentially toxic elements may fallout onto the soils, waters and vegetation of the Pinewood, arising general concern on the preservation of the forest. The important traffic rolling on the road net contouring the Pinewood-Lagoon ecosystem is a further source of pollution, as indicated by the incoming diffusion of PGE on the topsoils bordering the roads. Lastly, the study of the bottom deposits of the Lagoon at the water-sediment interface has unveiled the diffuse presence of Hg with significant concentrations, derived from industrial wastewaters unloaded in the basin some decades ago. Luckily, Hg occurs in the element form and, thus, its mobility is very reduced, keeping so far the risk factor in the Lagoon low. As a whole, the Pinewood-Lagoon ecosystem is ailing due to incoming salinization processes and, subordinately, moderate pollution proceedin

The final conclusions of a multidisciplinary study of Earth and Soil Sciences, carried out in the frame of Prin 2007 are presented. The study has dealt with a variety of natural materials, encompassing soils, waters, atmospheric depositions, the vegetation and the bottom sediments of a coastal lagoon, in the territory north of Ravenna, characterized by important agricultural and industrial activities. In particular, by chemical and isotopic methodologies and pedological survey, it has been studied the ecosystem of the San Vitale Pinewood and the Lagoon of Pialassa Baiona, both constituting the southernmost part of the Po river delta Park. The results obtained have shown that the Pinewood is affected by major salinization processes induced by local subsidence and concerning underground water and soils. This jeopardizes the vegetation's health, in particular, the pine trees that are the main characteristic species. Moreover, the proximity of the industrial zone of Ravenna to the Pinewood represents another threat to the environment, as it is a major pollution source by release of particulate matter with stacks. Therefore, potentially toxic elements may fallout onto the soils, waters and vegetation of the Pinewood, arising general concern on the preservation of the forest. The important traffic rolling on the road net contouring the Pinewood-Lagoon ecosystem is a further source of pollution, as indicated by the incoming diffusion of PGE on the topsoils bordering the roads. Lastly, the study of the bottom deposits of the Lagoon at the water-sediment interface has unveiled the diffuse presence of Hg with significant concentrations, derived from industrial wastewaters unloaded in the basin some decades ago. Luckily, Hg occurs in the element form and, thus, its mobility is very reduced, keeping so far the risk factor in the Lagoon low. As a whole, the Pinewood-Lagoon ecosystem is ailing due to incoming salinization processes and, subordinately, moderate pollution proceedin

The S. Vitale Pinewood represents an historical landmark in coastal Romagna. It developed on an old dune system in the north of Ravenna area, and is bordered by the Pialassa Baiona lagoon. After the first year of integrated studies on the different environmental matrices present in this area, some preliminary results are reported. Waters from the saturated zone are rarely composed of freshwater; they are generally brackish waters of variable composition, ranging from NaCl, Na-CaCl, NaCl-HCO3,Ca-MgHCO3 and NaHCO3, suggesting the different effects of intrusion and freshening. In particular, soil waters from the southernmost area of the Pinewood are generally the more saline. Chemical analyses of more than 30 major and trace ions, including the REE not usually determined in both surface and underground water samples, have shown no evidence of significant pollution by human activities. Sr, B, H and O isotopes have revealed to be useful markers for tracing the seawater intrusion in terms of both conservative parameters and cation-exchange processes. In addition, Sr isotopes have allowed to determine the possible sources of Sr and Ca as a proxy, thus providing information on a basic nutrient for the Pinewood vegetation, and giving indications on the possible contribution of fertilizers to the Sr isotopic budget. The apparent underground water flow encompasses about 75 years on the basis of the measured 226Ra/222Rn ratios. Chemical and mineralogical analyses of the soil horizons of 9 profiles located in the Pinewood have provided a bulk characterization integrated by the evaluation of the bioavailable fractions of both nutrient and toxic elements, including the REE and PGE. In particular, there is a significant enrichment of Pb and, to a lower extent, Zn and Cu in the topmost horizons. Sr isotopes have brought evidence of the significant contribution of seasalts to soils by atmospheric deposition, and have supported the origin of the dune sands from the basins of both the

A multidisciplinary study has been carried out on a 51 m long core, drilled on coastal lowlands near the Albegna River (Tuscany, Central Italy). Both sedimentological and faunal analyses (ostracods and molluscs) indicate a coastal lagoon environment repeatedly influenced both by the rising Holocene sea and the Albegna River alluvial inflow. d13C, d18O, Mg=Ca, Sr=Ca and 87Sr=86Sr analyses were performed on Cyprideis torosa shells in order to detail the influence of Albegna River freshwater on the coastal lagoon water. The analytical data illustrate the difficulties of using geochemical proxies in marginal marine settings. Four radiocarbon dates provide a chronostratigraphy for the early Holocene part of the core. The data are used to reconstruct Late Pleistocene to early Holocene palaeoenvironments along this part of the coast and show the development of freshwater environments followed by a coastal brackish lagoon formed in response to the initial Holocene rapid rise in relative sea level. An attempt is made to relate sediments and age data from the core to the relative sea-level curve for the Tyrrhenian Sea. Ó 1999 Elsevier Science B.V. All rights reserved.

The Apuane Alps core complex underwent polyphasic deformation and greenschist facies metamorphism during the Apennine orogeny. Several types of deposit occur within its Palaeozoic basement. At Pollone, barite-pyrite-polymetallic stratiform (syngenetic) bodies and metamorphogenic veins are spatially associated. Sr isotope ratios seem to be systematically higher in vein barites than in stratiform bodies. The features suggest a scarce remobilisation of stratiform barite and a channelled, rather than pervasive, style of circulation of mineralising fluids. The relatively high Sr isotope ratio in vein barites indicates a radiogenic source. Radiogenic S may have been released by the breakdown of Rb-bearing silicates in basement rocks; this would agree with a previous study of host rock Rb geochemistry., The Apuane Alps core complex underwent polyphasic deformation and greenschist facies metamorphism during the Apennine orogeny. Several types of deposit occur within its Palaeozoic basement. At Pollone, barite-pyrite-polymetallic stratiform (syngenetic) bodies and metamorphogenic veins are spatially associated. Sr isotope ratios seem to be systematically higher in vein barites than in stratiform bodies. The features suggest a scarce remobilisation of stratiform barite and a channelled, rather than pervasive, style of circulation of mineralising fluids. The relatively high Sr isotope ratio in vein barites indicates a radiogenic source. Radiogenic S may have been released by the breakdown of Rb-bearing silicates in basement rocks; this would agree with a previous study of host rock Rb geochemistry.

The fluorite-bearing hydrothermal mineralisation occurs mainly within Palaeozoic volcanic and metasedimentary rocks, with only three occurrences being located in Cainozoic volcanic and siliciclastic rocks. Most of the fluorites exhibit relatively high rare-earth and Y (REY) contents, strong positive Y anomalies, slightly negative Ce and generally positive Eu anomalies indicating that the REY were mobilised mainly from non-carbonate rocks. Mixing probably occurred between diluted surficial waters and brines circulating mainly through the Lower Palaeozoic metasedimentary basement. The Cainozoic fluorites exhibit chemical and isotopic features similar to those of the Palaeozoic fluorites, but the Nuraghe Onigu fluorite displays a possible contribution of Sr from Cainozoic magmatic rocks. The data suggest that radiogenic Nd was provided to the fluids from the Ordovician siliciclastic basement, except for three deposits where the potential source rocks of Nd were mainly Ordovician acidic magmatic rocks. The results for the Cainozoic fluorites suggest a provenance of Nd essentially from the leaching of Variscan granitoids., The fluorite-bearing hydrothermal mineralisation occurs mainly within Palaeozoic volcanic and metasedimentary rocks, with only three occurrences being located in Cainozoic volcanic and siliciclastic rocks. Most of the fluorites exhibit relatively high rare-earth and Y (REY) contents, strong positive Y anomalies, slightly negative Ce and generally positive Eu anomalies indicating that the REY were mobilised mainly from non-carbonate rocks. Mixing probably occurred between diluted surficial waters and brines circulating mainly through the Lower Palaeozoic metasedimentary basement. The Cainozoic fluorites exhibit chemical and isotopic features similar to those of the Palaeozoic fluorites, but the Nuraghe Onigu fluorite displays a possible contribution of Sr from Cainozoic magmatic rocks. The data suggest that radiogenic Nd was provided to the fluids from the Ordovician siliciclastic basement, except for three deposits where the potential source rocks of Nd were mainly Ordovician acidic magmatic rocks. The results for the Cainozoic fluorites suggest a provenance of Nd essentially from the leaching of Variscan granitoids.

The fluorite-barite +/-sulphide deposit is hosted in a Jurassic carbonate platform known as the Jbel Tirremi dome. The orebodies occur as open-space fillings and partial to massive replacement of the enclosing dolomitised limestones. Rare earth element compositions along with fluid inclusion, halogen and isotopic data suggest that the mineralisation and the spatially associated Eocene alkaline magmatism were petrogenetically unrelated, pointing instead to the regional circulation of hydrothermal basinal brines mixed to various degrees with meteoric water in a dominantly closed rock-buffered system at progressively higher temperatures and fluid/rock ratios. Fluid inclusion microthermometric measurements and isotopic data show that the ore-bearing hydrothermal system developed in two separate stages of mineralisation. Both stages precipitated from saline fluids at shallow crustal levels. Petroleum-bearing fluid, released from overpressured portions of the Guercif Basin at lithostatic pressures, and bittern brines dominated the first stage of mineralisation during Late Miocene. Mixing of saline, oxidised, CaCl2- and sulphate-rich bittern brine with oil-bearing fluid resulted in fluorite precipitation. Conversely, in the second stage of mineralisation during Tortonian time, the hydrothermal system was open to influx of oxidised meteoric water as a consequence of upward migration of the Triassic salt-bearing diapir and associated pressure decrease., The fluorite-barite +/-sulphide deposit is hosted in a Jurassic carbonate platform known as the Jbel Tirremi dome. The orebodies occur as open-space fillings and partial to massive replacement of the enclosing dolomitised limestones. Rare earth element compositions along with fluid inclusion, halogen and isotopic data suggest that the mineralisation and the spatially associated Eocene alkaline magmatism were petrogenetically unrelated, pointing instead to the regional circulation of hydrothermal basinal brines mixed to various degrees with meteoric water in a dominantly closed rock-buffered system at progressively higher temperatures and fluid/rock ratios. Fluid inclusion microthermometric measurements and isotopic data show that the ore-bearing hydrothermal system developed in two separate stages of mineralisation. Both stages precipitated from saline fluids at shallow crustal levels. Petroleum-bearing fluid, released from overpressured portions of the Guercif Basin at lithostatic pressures, and bittern brines dominated the first stage of mineralisation during Late Miocene. Mixing of saline, oxidised, CaCl2- and sulphate-rich bittern brine with oil-bearing fluid resulted in fluorite precipitation. Conversely, in the second stage of mineralisation during Tortonian time, the hydrothermal system was open to influx of oxidised meteoric water as a consequence of upward migration of the Triassic salt-bearing diapir and associated pressure decrease.