Boron isotope geochemistry of Na-bicarbonate, Na-chloride, and Ca-chloride waters from the Northern Apennine Foredeep basin: other pieces of the sedimentary basin puzzle

The boron stable isotope ratio δ11B of 12 water samples representative of three chemical facies (fresh Na-bicarbonate, brackish Na-chloride, saline, and brine Ca-chloride) has been analyzed. Interpretation of the δ11B data, along with the chemical compositions, reveals that Na-carbonate waters from the Northern Apennine are of meteoric origin, with boron contributions from clay desorption and mixing with seawater-derived fluids of Na-chloride or Ca-chloride compositions. The comparison of our new results with the literature data on other sedimentary basins of Mediterranean, and worldwide, confirms the contribution of Na-bicarbonate waters to the genesis of mud volcano fluids. The Na-chloride sample of Salvarola (SAL), which may represent the end-member of the mud volcanoes, and the Ca-chloride brine water from Salsomaggiore (SM) indicate boron release from clays compatible with the diagenetic process. The empirical equation: δ11B=[5.1364×ln(1/B)mgl-1]+44.601relating boron concentration and the stable isotope composition of the fluids observed in this study and the literature is proposed to trace the effect of diagenesis in sedimentary basins. A geothermometer associated to the diagenetic equation is also proposed: T{ring operator}C=[δ11B-38.873(±1.180)]/[-0.164(±0.012)] The application of this equation to obtain reservoir temperatures from δ11B compositions of waters should be carefully evaluated against the results obtained from other chemical and isotopic geothermometers from other basins around the world

Sulfur and oxygen isotope compositions of Upper Triassic sulfates from northern Apennines (Italy) : paleogeographic and hydrogeochemical implications

Upper Triassic bedded evaporite sulfate of the Burano Formation outcropping at Cerreto Pass between Tuscany and Emilia-Romagna in the Northern Apennines were analyzed for sulfur and oxygen isotope compositions, yielding d34S and d18O values of 15.5±0.4‰ and 10.8±1.2‰, respectively (mean ±99% confidence intervals). Combining these values with those of other Burano Formation sulfate deposits along the Apennine chain, mean for d34S and d18O values are obtained (15.2±0.2‰ and 10.9±0.5‰, respectively). These isotopic signatures are interpreted as preserved primary features, despite the fact that the Burano Formation underwent anchizone to epizone metamorphism during the Apennine orogenesis. An overall d18O value of 10.9±1.5‰ (mean ± pooled standard deviation), obtained by combining consistent sets of data from Italy and Spain, closely approaches that of gypsum deposited from the Tethys ocean during the Late Triassic. In addition, reviewing the isotope data published on Late Triassic evaporite sulfates from the Mediterranean area and abroad, several d34S values appear to be lower than the inferred primary isotopic signature, and seemly decrease from East to West in the Mediterranean region, suggesting a similar trend for the Tethys ocean sulfate. Possibly, 34S-depleted sulfate entered the ocean through oxidation of volcanic SO2 emitted in the atmosphere and degassed from the seafloor during the development of Late Triassic rifting. On the other hand, positive shifts of d34S and d18O values also occur, defining a common trend that may be related to synsedimentary biological effects or post-depositional metasomatic-metamorphic effects, the latter affecting particularly the d18O signature. Therefore, the d34S and d18O signatures of evaporite sulfate may provide a like "slide-rule" diagram to distinguish between isotopic effects related to biological or abiological processes, thus contributing to the reconstruction of paleoenvironments and paleogeographic settings. Based on the d34S-d18O "slide-rule", the isotopic composition of sulfate dissolved in spring and stream waters of northern Tuscany was interpreted in terms of origin of the sulfate and modifying processes in solution. It was concluded that sulfate in springs derives from Upper Triassic evaporite existing locally at depth (Burano Formation), whereas sulfate in streams is manifestly a mixture of Burano Formation sulfate with supergene sulfate from oxidation of sulfide in the rocks. In sulfurous springs, both sulfur and oxygen isotope fractionations with respect to the source sulfate signatures may be ascribed to bacterial effects. However, the oxygen isotope exchange of sulfate with water should have been a very minor process as supported by the nearsurface temperature values estimated by sulfate-water oxygen isotope thermometry

Hydrogeochemistry and groundwater quality assessment in a municipal solid waste landfill (central Italy)

Municipal solid waste landfills leachate can cause serious environmental issues for groundwater quality. Therefore, the application of environmental tracing methods to identify groundwater contamination by municipal solid waste landfills leachate is significant. Hydrogeochemical evaluations to trace municipal solid waste landfills leachate are usually carried out. The study was carried out at a landfill in central Italy (Umbria). Samples of leachate and groundwater have been analyzed to evaluate the impact of leachates on groundwater through the comparison of their hydrogeochemical nature. Parameters like pH, Temperature (T), Electrical Conductivity (EC), redox potential (Eh) and Chemical Oxygen Demand (COD) were also measured in situ using digital instruments. Hydrogeochemical data (Na+, K+, Mg2+, Ca2+, SO42−, HCO3−, Cl−, NO3−), ionic ratios and geochemical correlations were used to confirm the processes that govern the chemistry of the spring water and to identify leachate contamination phenomena. In fact, the main geochemical diagrams (Langelier-Ludwig, Piper, Schoeller) confirm the leachate contamination in a groundwater sample. In particular, the Piper diagram shows that a sample is in Na+ – Cl- – HCO3- mixing zone, indicating a possible influence of the leachate on groundwater chemistry. As a matter of fact, some correlations between major elements, such as Cl- versus Na+ and Cl- versus HCO3-, confirm that the leachate in this study area is highly enriched in Cl- and HCO3- due to wastes dissolution and degradation processes. Further, the assessment of K+/Mg2+ ratio also confirms the presence of a sample heavily impacted from leachate contamination. These results indicate that also one basic hydrogeochemical study can be useful for fingerprinting the leachate pollution for groundwater samples

Octave bias in an absolute pitch identification task

Octave errors are common within musicians, even among absolute pitch possessors. Overall, evidence shows pitch class and octave to be perceived in a different way, even if they are highly connected. We investigated whether pitch class perception, in an absolute pitch identification task, can be influenced by the octave context, examined among two consecutive octaves. Participants, all musicians with formal musical education, showed different response patterns in the two octaves even if the octave context was explicitly told to be task irrelevant. The direction of errors revealed a consistent tendency to underestimate pitch height in the lowest octave and to overestimate pitch height in the highest octave. Thus, pitch class identification showed to be biased by the octave context. These results are discussed in terms of polarity and pitch enhancement

Hydrogeochemical characterization of oilfield waters from southeast Maracaibo Basin (Venezuela): diagenetic effects on chemical and isotopic composition

Free water and water in emulsion with oil from hydrocarbon wells onshore-offshore Lake Maracaibo were extracted and analyzed. The use of classical and new chemical diagrams evidenced that Na-HCO3 and Na- Cl are the main chemical facies, whereas Na-SO4 facies was rare and revealed only in faulted areas in which shallow groundwater was involved in deep circulation. Cretaceous Ca-Cl waters were not revealed, but their imprint on some samples was traced and evidenced by Langelier-Ludwig, Brine-Differentiation and Caexcess vs. Nadeficit diagrams. These square plots, allowing a discrimination between the water contributions from the different source rocks, should be more exploited as hydrogeochemical tools in hydrocarbon exploration. Original data on monocarboxylic anions showed acetate concentration higher than ten times that of formate at sampling conditions, but speciation under deep conditions indicated a reversed activity dominance. Calculation of saturation indexes and kinetic modeling showed an active precipitation of chalcedony, kaolinite and clays, especially where the temperature was lower (T < 100 °C). Formation waters and lake water showed quite similar chloride concentration and hydrogen isotope composition. However, thermodynamic calculations at the oilfield P-T conditions revealed chlorite and illite, produced during previous diagenetic stages of Misoa sandstones, recrystallization to smectite and vermiculite in present-day stage. The diagenetic water produced in these reactions could have enriched the delta18O isotopic composition of approximately +2‰. This isotope diagenetic effect was more evident in Na-HCO3 waters, which also showed a decrease in chloride at constant boron as a consequence of clay dewatering. In this regard, a new boron geothermometer useful for formation waters is also proposed

Multi-stage rodingitization of ophiolitic bodies from Northern Apennines (Italy): Constraints from petrography, geochemistry and thermodynamic modelling

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Understanding the Origin and Mixing of Deep Fluids in Shallow Aquifers and Possible Implications for Crustal Deformation Studies: San Vittorino Plain, Central Apennines

Expanding knowledge about the origin and mixing of deep fluids and the water–rock–gas interactions in aquifer systems can represent an improvement in the comprehension of crustal deformation processes. An analysis of the deep and meteoric fluid contributions to a regional groundwater circulation model in an active seismic area has been carried out. We performed two hydrogeochemical screenings of 15 springs in the San Vittorino Plain (central Italy). Furthermore, we updated the San Vittorino Plain structural setting with a new geological map and cross-sections, highlighting how and where the aquifers are intersected by faults. The application of Na-Li geothermometers, coupled with trace element and gas analyses, agrees in attributing the highest temperatures (&gt;150 °C), the greatest enrichments in Li (124.3 ppb) and Cs (&gt;5 ppb), and traces of mantle-derived He (1–2%) to springs located in correspondence with high-angle faults (i.e., S5, S11, S13, and S15). This evidence points out the role of faults acting as vehicles for deep fluids into regional carbonate aquifers. These results highlight the criteria for identifying the most suitable sites for monitoring variations in groundwater geochemistry due to the uprising of deep fluids modulated by fault activity to be further correlated with crustal deformation and possibly with seismicit

Chemical and stable isotope composition (18O/16O, 2H/1H) of formation waters from the Carabobo Oilfield, Venezuela

In this short note, we present the first data on stable isotope composition of the oilfield waters from Carabobo area of the Faja Petrolífera del Orinoco "Hugo Chávez" (Orinoco Oil Belt). From a chemical point of view, the formation waters show a main Na-Cl level (TDS up to 30g/l) with a dilution trend toward Na-HCO3 composition (down to 1g/l). Until now, such a clear net chemical compositional trend was ascribed to a meteoric dilution (fresh/ brackish bicarbonate) of the seawater endmember (the saltiest chloride). The isotope results of this study reveal that the seawater mother water was modified during a high-temperature thrusting event (120-125°C), forming 18O-enriched diagenetic water (up to +4‰), which was diluted in recent times by glacial meltwater and presentday meteoric water. The hypothetical presence of flood by a meteoric paleo-water also offers new hints to explain the low API gravity (<10°API biodegraded, extra heavy oil) and composition of the local crude

Octave Bias in Pitch Perception: The Influence of Pitch Height on Pitch Class Identification

The Publisher's final version can be found by following the DOI link (open access).Pitch height and pitch class are different, but strictly related, percepts of music tones. To investigate the influence of pitch height in a pitch class identification task, we systematically analyzed the errors—in terms of direction and amount—committed by a group of musicians. The aim of our study was to verify the existence of constant errors in the identification of pitch classes across consecutive octaves. Stimuli were single piano tones from the C major scale executed in two consecutive octaves. Participants showed different response patterns in the two octaves. The direction of errors revealed a constant tendency to underestimate pitch classes in the lowest octave and to overestimate pitch classes in the highest octave. Thus, pitch height showed to influence pitch class identification. We called this bias ‘‘pitch class polarization’’, since the same pitch class was judged to be respectively lower and higher, depending on relatively low or high pitch height

Recharge, groundwater flow pattern and contamination processes in an arid volcanic area: Insights from isotopic and geochemical tracers (Bara aquifer system, Republic of Djibouti)

Fractured volcanic aquifers are the main water resources in the arid climate of the Republic of Djibouti. Nonetheless, these strategic reservoirs are overexploited and their comprehensive understanding is therefore a pre-requisite for a sustainable use. A geochemical and isotopic survey, including major ion chemistry, 2H, 18O, 13C, 3H, 87Sr/86Sr, 15N was performed and combined with existing 14C data to study recharge, contamination processes and groundwater flow patterns inside and between the compartments of a complex aquifer system composed by basaltic rocks and by alluvium located in Petit Bara, Grand Bara, and Mouloud areas (Southwest of Djibouti). A main feature was the common trend from a fresh Na-Cl-HCO3 water type (alluvium groundwaters) to an intermediate water type (alluvium and basalt groundwaters) and finally to a Na-Cl-SO4 water type (most mineralized basalt groundwater). Elementary and isotopic nitrate evidenced and located anthropogenic and geogenic origins of nitrate. Alluvium groundwaters had δ2H and δ18O signature of modern precipitation while basalt groundwaters were significantly depleted and enriched in δ13C due to water-rock interactions. Modern radiocarbon and tritium were evidenced in the alluvium groundwaters, while recalculated radiocarbon ages located recharge of the basalt groundwaters in the early to mid-Holocene. These features revealed a common evolutionary pattern, with a recharge from wadi-rivers to the alluvium and a downward circulation to the basalt through major faults, combined with a mixing with a more geochemically evolved groundwater. Accordingly, highly saline groundwater at the outlet of the Petit Bara plain was found to be diluted by modern recharge in the alluvium. Two major basaltic aquifer compartments were found to be connected (Grand Bara and Mouloud), revealing a global northeastward flowpath below the endorheic Grand Bara plain