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  • 1
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    Shallow submarine mud volcano in the northern Tyrrhenian sea, Italy (2020)
    Elsevier
    Details
    Publication Date: 2023-11-16
    Description: Submarine methane emissions in the Tuscan Archipelago have been studied since the 1960s, both for economic and research purposes. Offshore gas seepage is mainly concentrated southward and westward of Elba island, along N–S faults related to recent extensional activity in the Tuscan shelf and N–S trending positive magnetic anomalies, which have been interpreted as serpentinites associated with ophiolitic rocks due to their very high magnetic susceptibility. This study focuses on the gas chemistry of a new emission site corresponding to a shallow water mud volcano in the Scoglio d’Affrica area. The Scoglio d’Affrica seep has a gas composition typical of mud volcanoes, with methane as the prevalent component (95 vol%) and minor gases which include carbon dioxide, nitrogen and trace amounts of helium. The combined stable C and H isotope composition of CH4 (δ13C and δ2H) and the enrichment in heavy carbon isotopes of CO2, highlight a prevalent secondary microbial origin for these fluids (δ13C~− 35.8‰ vs VPDB; δ2H~− 166‰ vs VSMOW; δ13CCO2 up to + 21.7‰ vs VPDB). Thus, in spite of the occurrence of positive magnetic anomalies, a possible abiotic origin of methane is excluded. Moreover, the gas from the mud volcano is extremely depleted in 3He and presents typical 3He/4He ratios of a geological setting in which radiogenic crustal helium is strongly predominant. A photo-mosaic of the mud volcano is also reported. A possible connection with other submarine methane emissions in the Tuscan Archipelago is limited to emissions located few kilometers from the Scoglio d’Affrica area. Recent emissions in the area suggest that gases similar in composition from distinct reservoirs, find their way to the surface from Eocene deposits in different time intervals and through different faults and fractures, placed along the Elba-Pianosa ridge.
    Description: Published
    Description: 104722
    Description: 6A. Geochimica per l'ambiente e geologia medica
    Description: JCR Journal
    Keywords: Submarine emission ; Mud volcano ; Methane ; Gas geochemistry ; Tyrrhenian sea ; Geochemistry ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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    PAPER (OA)
  • 2
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    Miocene to present oceanographic variability in the Scotia Sea and Antarctic ice sheets dynamics: Insight from revised seismic-stratigraphy following IODP Expedition 382 (2021)
    Elsevier
    Details
    Publication Date: 2024-02-07
    Description: Highlights • Core-log-seismic correlation allows to assign ages to the Scotia Sea seismic record. • Major implications are derived on the relation between regional and global events. • The main stratigraphic events are much younger than previously proposed. • Three major phases for the regional oceanography are observed from late Miocene. • These phases appear to be closely linked to the Antarctic Ice Sheet dynamics. Scotia Sea and the Drake Passage is key towards understanding the development of modern oceanic circulation patterns and their implications for ice sheet growth and decay. The sedimentary record of the southern Scotia Sea basins documents the regional tectonic, oceanographic and climatic evolution since the Eocene. However, a lack of accurate age estimations has prevented the calibration of the reconstructed history. The upper sedimentary record of the Scotia Sea was scientifically drilled for the first time in 2019 during International Ocean Discovery Program (IODP) Expedition 382, recovering sediments down to ∼643 and 676 m below sea floor in the Dove and Pirie basins respectively. Here, we report newly acquired high resolution physical properties data and the first accurate age constraints for the seismic sequences of the upper sedimentary record of the Scotia Sea to the late Miocene. The drilled record contains four basin-wide reflectors – Reflector-c, -b, -a and -a' previously estimated to be ∼12.6 Ma, ∼6.4 Ma, ∼3.8 Ma and ∼2.6 Ma, respectively. By extrapolating our new Scotia Sea age model to previous morpho-structural and seismic-stratigraphic analyses of the wider region we found, however, that the four discontinuities drilled are much younger than previously thought. Reflector-c actually formed before 8.4 Ma, Reflector-b at ∼4.5/3.7 Ma, Reflector-a at ∼1.7 Ma, and Reflector-a' at ∼0.4 Ma. Our updated age model of these discontinuities has major implications for their correlation with regional tectonic, oceanographic and cryospheric events. According to our results, the outflow of Antarctic Bottom Water to northern latitudes controlled the Antarctic Circumpolar Current flow from late Miocene. Subsequent variability of the Antarctic ice sheets has influenced the oceanic circulation pattern linked to major global climatic changes during early Pliocene, Mid-Pleistocene and the Marine Isotope Stage 11.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: other
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Shear-wave velocity structure beneath the Dinarides from the inversion of Rayleigh-wave dispersion (2021)
    Elsevier
    Details
    Publication Date: 2024-02-07
    Description: Highlights • Rayleigh-wave phase velocity in the wider Dinarides region using the two-station method. • Uppermost mantle shear-wave velocity model of the Dinarides-Adriatic Sea region. • Velocity model reveals a robust high-velocity anomaly present under the whole Dinarides. • High-velocity anomaly reaches depth of 160 km in the northern Dinarides to more than 200 km under southern Dinarides. • New structural model incorporating delamination as one of the processes controlling the continental collision in the Dinarides. The interaction between the Adriatic microplate (Adria) and Eurasia is the main driving factor in the central Mediterranean tectonics. Their interplay has shaped the geodynamics of the whole region and formed several mountain belts including Alps, Dinarides and Apennines. Among these, Dinarides are the least investigated and little is known about the underlying geodynamic processes. There are numerous open questions about the current state of interaction between Adria and Eurasia under the Dinaric domain. One of the most interesting is the nature of lithospheric underthrusting of Adriatic plate, e.g. length of the slab or varying slab disposition along the orogen. Previous investigations have found a low-velocity zone in the uppermost mantle under the northern-central Dinarides which was interpreted as a slab gap. Conversely, several newer studies have indicated the presence of the continuous slab under the Dinarides with no trace of the low velocity zone. Thus, to investigate the Dinaric mantle structure further, we use regional-to-teleseismic surface-wave records from 98 seismic stations in the wider Dinarides region to create a 3D shear-wave velocity model. More precisely, a two-station method is used to extract Rayleigh-wave phase velocity while tomography and 1D inversion of the phase velocity are employed to map the depth dependent shear-wave velocity. Resulting velocity model reveals a robust high-velocity anomaly present under the whole Dinarides, reaching the depths of 160 km in the north to more than 200 km under southern Dinarides. These results do not agree with most of the previous investigations and show continuous underthrusting of the Adriatic lithosphere under Europe along the whole Dinaric region. The geometry of the down-going slab varies from the deeper slab in the north and south to the shallower underthrusting in the center. On-top of both north and south slabs there is a low-velocity wedge indicating lithospheric delamination which could explain the 200 km deep high-velocity body existing under the southern Dinarides.
    Type: Article , PeerReviewed
    Format: text
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    How can biogeomechanical alterations in shales impact caprock integrity and CO2 storage? (2021)
    Elsevier
    Details
    Publication Date: 2023-01-04
    Description: Highlights • Coupled geomicrobiology and geomechanics to investigate alterations in shales. • Microbial process can alter the mechanics, mineralogy, and microstructure of shales. • Biogeomechanical alterations reduced permeability by 93% and porosity by 38%. • Microfractures in shales can be sealed during biogeomechanical alterations. • Biogeomechanical alterations can enhance CO2 storage security and caprock integrity. Shales have been a major focus of the energy industry over the past few decades. Recently, there is a paradigm shift in the energy industry to low-carbon solutions, such as carbon capture and storage (CCS), to mitigate global warming caused by carbon footprint. The problem of long-term safe and efficient geological CO2 storage (GCS) and caprock integrity are some of the major challenges impeding large-scale CCS application. Here, we investigated how localized and bulk biogeomechanical alterations could potentially impact caprock integrity and CO2 storage in depleted shale reservoirs. We cultivated the shale core samples (containing both artificial-induced and pre-existing natural fractures) with a cultured microbial solution at specific temperature, time, and growth conditions. Subsequently, we obtain the properties of the fractured shale rock samples impacted by this microbial process. We investigate the impact of the mechanical responses due to the microbial process, on the long-term integrity and storage potentials of CO2 in shale reservoirs. Our results suggest that in Eagle Ford, Marcellus, and Niobrara shale formations, microbially-altered local and bulk mechanical properties can enhance the long-term caprock integrity and CO2 storage security by: (1.) Increasing the localized (+19% unconfined compressive strength, −20% Poisson’s ratio, +35% fracture toughness) and bulk (+50% unconfined compressive strength, −13% Poisson’s ratio) mechanical integrity; (2.) Decreasing permeability (−93%) and porosity (−38%); (3.) Altering the clay mineral content (−56%), calcite content (+21%), and morphology; (4.) Occluding microfractures; and (5.) Mitigating any potential leakage to the atmosphere through the caprock. This study considers the heterogeneity of shales, and provide valuable insights and viable assessment in solving the long-term GCS application in depleted hydrocarbon reservoirs.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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