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  • 04.07. Tectonophysics  (3)
  • Hydrothermal systems  (3)
  • Elsevier  (6)
  • American Association for the Advancement of Science (AAAS)
  • American Association of Petroleum Geologists (AAPG)
  • American Geophysical Union (AGU)
  • 2020-2022  (6)
  • 1965-1969
  • 2020  (6)
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Year
  • 1
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    Tidal modulation of plate motions (2020)
    Elsevier
    Details
    Publication Date: 2020-09-07
    Description: While mantle convection is a fundamental ingredient of geodynamics, the driving mechanism of plate tectonics remains elusive. Are plates driven only from the thermal cooling of the mantle or are there further astronomical forces acting on them? GPS measurements are now accurate enough that, on long baselines, both secular plate motions and periodic tidal displacements are visible. The now 〉20 year-long space geodesy record of plate motions allows a more accurate analysis of the contribution of the horizontal component of the body tide in shifting the lithosphere. We review the data and show that lithospheric plates retain a non-zero horizontal component of the solid Earth tidal waves and their speed correlates with tidal harmonics. High-frequency semidiurnal Earth's tides are likely contributing to plate motions, but their residuals are still within the error of the present accuracy of GNSS data. The low-frequency body tides rather show horizontal residuals equal to the relative motion among plates, proving the astronomical input on plate dynamics. Plates move faster with nu- tation cyclicities of 8.8 and 18.6 years that correlate to lunar apsides migration and nodal precession. The high- frequency body tides are mostly buffered by the high viscosity of the lithosphere and the underlying mantle, whereas low-frequency horizontal tidal oscillations are compatible with the relaxation time of the low-velocity zone and can westerly drag the lithosphere over the asthenospheric mantle. Variable angular velocities among plates are controlled by the viscosity anisotropies in the decoupling layer within the low-velocity zone. Tidal oscillations also correlate with the seismic release.
    Description: Published
    Description: 103179
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: Body tide ; Plate tectonics ; Geeodynamics ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Present-day uplift of the European Alps: Evaluating mechanisms and models of their relative contributions (2020)
    Elsevier
    Details
    Publication Date: 2021-06-25
    Description: Recent measurements of surface vertical displacements of the European Alps show a correlation between vertical velocities and topographic features, with widespread uplift at rates of up to ~2–2.5 mm/a in the North-Western and Central Alps, and ~1 mm/a across a continuous region from the Eastern to the South-Western Alps. Such a rock uplift rate pattern is at odds with the horizontal velocity eld, characterized by shortening and crustal thickening in the Eastern Alps and very limited deformation in the Central and Western Alps. Proposed me- chanisms of rock uplift rate include isostatic response to the last deglaciation, long-term erosion, detachment of the Western Alpine slab, as well as lithospheric and surface de ection due to mantle convection. Here, we assess previous work and present new estimates of the contributions from these mechanisms. Given the large range of model estimates, the isostatic adjustment to deglaciation and erosion are su cient to explain the full observed rate of uplift in the Eastern Alps, which, if correct, would preclude a contribution from horizontal shortening and crustal thickening. Alternatively, uplift is a partitioned response to a range of mechanisms. In the Central and Western Alps, the lithospheric adjustment to deglaciation and erosion likely accounts for roughly half of the rock uplift rate, which points to a noticeable contribution by mantle-related processes such as detachment of the European slab and/or asthenospheric upwelling. While it is di cult to independently constrain the patterns and magnitude of mantle contributions to ongoing Alpine vertical displacements at present, future data should provide additional insights. Regardless, interacting tectonic and surface mass redistribution processes, rather than an individual forcing, best explain ongoing Alpine elevation changes.
    Description: Published
    Description: 589-604
    Description: 1T. Struttura della Terra
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: 04. Solid Earth ; 04.03. Geodesy ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    Tectonics and seismicity in the Northern Apennines driven by slab retreat and lithospheric delamination (2020)
    Elsevier
    Details
    Publication Date: 2020-06-10
    Description: Understanding how long-term subduction dynamics relates to the short-term seismicity and crustal tec tonics is a challenging but crucial topic in seismotectonics. We attempt to address this issue by linking long-term geodynamic evolution with short-term seismogenic deformation in the Northern Apennines. This retreating subduction orogen displays tectonic and seismogenic behaviors on various spatiotemporal scales that also characterize other subduction zones in the Mediterranean area. We use visco-elasto-plastic seismo-thermo-mechanical (STM) modeling with a realistic 2D setup based on available geological and geophysical data. The subduction dynamics and seismicity are coupled in the numerical modeling, and driven only by buoyancy forces, i.e., slab pull. Our results suggest that lower crustal rheology and lithospheric mantle temperature modulate the crustal tectonics of the Northern Apennines, as inferred by previous studies. The observed spatial distribution of upper crustal tectonic regimes and surface displacements requires buoyant, highly ductile material in the subduction channel beneath the internal part of the orogen. This allows protrusion of the asthenosphere in the lower crust and lithospheric delamination associated with slab retreat. The resulting surface velocities and principal stress axes generally agree with present-day observations, suggesting that slab delamination and retreat can explain the dynamics of the orogen. Our simulations successfully reproduce the type and overall distribution of seismicity with thrust faulting events in the external part of the orogen and normal faulting in its internal part. Slab temperatures and lithospheric mantle stiffness affect the cumulative seismic moment release and spatial distribution of upper crustal earthquakes. The properties of deep, sub-crustal material are thus shown to influence upper crustal seismicity in an orogen driven by slab retreat, even though the upper crust is largely decoupled from the lithospheric mantle. Our simulations therefore highlight the effect of deep lower crustal rheologies, self-driven subduction dynamics and mantle properties in controlling shallow deformation and seismicity.
    Description: Published
    Description: 228481
    Description: 1T. Struttura della Terra
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: Numerical modeling ; Geodynamics ; Seismotectonics orogen ; Delamination ; Northern Apennines ; 04.06. Seismology ; 04.03. Geodesy ; 05.01. Computational geophysics ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
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    Methanotrophy in geothermal soils, an overlooked process: The example of Nisyros island (Greece) (2020)
    Elsevier
    Details
    Publication Date: 2020-07-13
    Description: A multidisciplinary field campaign was carried out at Nisyros Island (Greece). Hydrothermal gases were sampled and analysed, and CH4 and CO2 fluxes from the soils were measured with the accumulation chamber method. The sampling area (Lakki plain) covers an area of about 0.08 km2, and includes the main fumarolic areas of Kaminakia, Stefanos, Ramos, Lofos and Phlegeton. Flux values measured at 130 sites range from −3.4 to 1420 mg m−2 d−1 for CH4 and from 0.1 to 383 g m−2 d−1 for CO2. The fumarolic areas show very different CH4 degassing patterns, Kaminakia showing the highest CH4 output values (about 0.8 t a−1 from an area of about 30,000 m2) and Phlegeton the lowest (about 0.01 t a−1 from an area of about 2500 m2). The total output from the entire geothermal system of Nisyros should not exceed 2 t a−1. Previous indirect estimates of the CH4 output at Nisyros, based on soil CO2 output and CH4/CO2 ratios in fumarolic gases, were more than one order of magnitude higher. The present work further underscores the utmost importance of direct CH4 flux data because indirect methods totally disregard methanotrophic activity within the soil. Ten soil samples were collected for CH4 consumption experiments and for metagenomic analysis. Seven of the soil samples showed small but significant CH4 consumption (up to 39.7 ng g−1 h−1) and were positive for the methanotrophs-specific gene (pmoA) confirming microbial CH4 oxidation in the soil, notwithstanding the harsh environmental conditions (high temperature and H2S concentrations and low pH).
    Description: Published
    Description: 119546
    Description: 6A. Geochimica per l'ambiente e geologia medica
    Description: JCR Journal
    Keywords: Methanotrophy ; Soil degassing ; Hydrothermal systems ; Methane output ; Greenhouse gases ; 05.09. Miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    Deep CO2 emitted at Furnas do Enxofre geothermal area (Terceira Island, Azores archipelago). An approach for determining CO2 sources and total emissions using carbon isotopic data (2020)
    Elsevier
    Details
    Publication Date: 2020-06-30
    Description: Quantification of the CO2 released by the volcanoes to the atmosphere is relevant for the evaluation of the balance between deep-derived, biogenic and anthropogenic contributions. The current study estimates the CO2 released from Furnas do Enxofre degassing area (Terceira Island, Azores archipelago) by applying an approach that integrates the flux of CO2 fromthe soilwith the δ13C-CO2 values. A deep-derived CO2 output of 2.54 t d−1 is estimated for an area of ~23,715 m2. High biogenic-derived CO2 flux values (~45 g m−2 d−1) associated with light carbon isotopic content (δ13C=−28‰±1.1‰) are detected and explained by the type of vegetation that characterizes the study site. Carbon isotopic compositions of the CO2 (−6.4‰±1.2‰) measured in olivine-hosted fluid inclusions of the Terceira basalts are presented for the first time and contribute to defining the mantle-CO2 signature. Differences between these values and heavier carbon isotope values from gas in fumaroles at Furnas do Enxofre (−4.66‰to−4.27‰) are explained by the carbon isotopic fractionation occurring when CO2 reacts to form calcite in the geothermal reservoir at temperatures N180 °C. A clear correlation between the soil temperature and deep CO2 fluxes is observed and the integration of the diffuse degassing information with the composition of the fumarolic emissions allows estimating a thermal energy flux of 1.1 MW.
    Description: Published
    Description: 106968
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: 4V. Processi pre-eruttivi
    Description: JCR Journal
    Keywords: Soil diffuse degassing ; CO2 fluxes ; Carbon isotopic composition ; Hydrothermal systems ; 04.08. Volcanology ; 04.01. Earth Interior
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    Geochemical features of hydrothermal systems in Jujuy Province, Argentina: Hints for geothermal fluid exploration (2020)
    Elsevier
    Details
    Publication Date: 2020-05-21
    Description: Fluid primary source(s) and chemical-physical processes controlling water and gas chemistry of thermal springs from Eastern Cordillera, sub-Andean Ranges and Santa Bárbara (Jujuy Province, northern Argentina) were investigated to provide information for a preliminary evaluation of the geothermal potential in these areas. Thermal manifestations in Eastern Cordillera (Reyes) and part of those in the western sector of sub-Andean Range (Aguas Calientes) are fed by shallow aquifers, interacting with Quaternary- Neogene rocks and the upper portion of Pliocene-Miocene formations (Orán Group), whereas the meteoric water recharge area is located at〉2500 m a.s.l., corresponding to Chañi hill. Differently, El Jordán thermal spring in the sub-Andean Range is fed by a hydrothermal aquifer hosted within highly porous and fractured formations of the Salta Group (Yacoraite Formation) and recharged by meteoric water from Sierra de Calilegua (∼1500m a.s.l.). The latter is the recharge area of the La Quinta geothermal waters as well, but these have been fed at higher altitudes (〉 2500 m a.s.l.) in the range. The hydrothermal reservoir feeding the other thermal springs from the Santa Barbara system (Caimancito, El Palmar, and Siete Aguas) is recharged by meteoric water from Zapla Ranges and Santa Barbara Hill at〈2500m a.s.l. The high-TDS (〉 16,000 mg/L) Na+-Cl- La Quinta thermal springs are produced by interaction with the evaporite deposits of Salta Group, including halite, whereas the chemistry of El Palmar, El Jordán and Caimancito thermal springs, showing a Na+-SO4 2-(Cl−) composition, depends on mixing with shallower SO4 2--rich waters interacting with gypsum deposits of Anta Formation. Dissolved and bubbling gases from all the investigated provinces are related to CO2- and CH4-rich crustal fluids produced by both thermogenic processes occurring within the hydrothermal systems and microbial activity at relatively low depth, with low to negligible mantle contribution, as indicated by the 3He/4He values ≤ 0.21 Ra. The fluid reservoir feeding the Quinta thermal springs shows the highest estimated temperatures (〉 200 °C), which, considering the depth of Salta Group in the Santa Barbara system (~2000 m), support the idea, suggested by previous authors, of an anomalous geothermal gradient for this area, a promising pre-requisite for future exploitation of the geothermal resource.
    Description: Published
    Description: 102627
    Description: 1TR. Georisorse
    Description: JCR Journal
    Keywords: Hydrothermal systems ; Fluid geochemistry ; Jujuy province ; Geothermal resource
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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