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  • 1
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    Abnormal fluid pressures and fault-zone dilation in the Barbados accretionary prism: Evidence from logging while drilling (1995)
    GSA, Geological Society of America
    In:  Geology, 23 (7). pp. 605-608.
    Details
    Publication Date: 2017-06-15
    Description: Logs collected while drilling measured density in situ, through the accretionary prism and decollement zone of the northern Barbados Ridge. Consolidation tests relate void ratio (derived from density) to effective stress and predict a fluid pressure profile, assuming that the upper 100 m of the prism is at a hydrostatic pressure gradient. The calculated fluid pressure curve rises to 〉90% of lithostatic below thrusts in the prism, presumably due to the increase in overburden and lateral tectonic loading. Thin (0.5–2.0 m) intervals of anomalously low density and resistivity in the logs through the basal decollement zone suggest dilation and perhaps hydrofracturing. A peak in hydraulic head in the upper half of the decollement zone requires lateral influx of fluid, a conclusion consistent with previous geochemical studies. Although the calculated fluid-pressure profile is model dependent, its inherent character ties to major structural features.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1130/0091-7613(1995)​023〈0605:AFPAFZ〉​2.3.CO;2
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
    facet.materialart.
    Unknown
    Abnormal fluid pressures and fault-zone dilation in the Barbados accretionary prism: Evidence from logging while drilling (1995)
    GSA, Geological Society of America
    In:  Geology, 23 (7). pp. 605-608.
    Details
    Publication Date: 2017-05-17
    Description: Logs collected while drilling measured density in situ, through the accretionary prism and decollement zone of the northern Barbados Ridge. Consolidation tests relate void ratio (derived from density) to effective stress and predict a fluid pressure profile, assuming that the upper 100 m of the prism is at a hydrostatic pressure gradient. The calculated fluid pressure curve rises to 〉90% of lithostatic below thrusts in the prism, presumably due to the increase in overburden and lateral tectonic loading. Thin (0.5–2.0 m) intervals of anomalously low density and resistivity in the logs through the basal decollement zone suggest dilation and perhaps hydrofracturing. A peak in hydraulic head in the upper half of the decollement zone requires lateral influx of fluid, a conclusion consistent with previous geochemical studies. Although the calculated fluid-pressure profile is model dependent, its inherent character ties to major structural features.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1130/0091-7613(1995)023〈0605:AFPAFZ〉2.3.CO;2
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Strain decoupling across the decollement of the Barbados accretionary prism (1996)
    GSA, Geological Society of America
    In:  Geology, 24 (2). pp. 127-130.
    Details
    Publication Date: 2017-04-10
    Description: The interrelation between deformation styles and behavior of fluids in accretionary prisms is under debate, particularly the possibility that overpressuring within the basal decollement may enable mechanical decoupling of the prism from the subducting material. Anisotropy of magnetic susceptibility (AMS) data from sediments spanning the basal decollement of the Barbados accretionary prism show a striking progression across this structure that strongly supports the hypothesis that it is markedly overpressured. In the accretionary prism, above the decollement, the minimum AMS axes are subhorizontal and oriented nearly east-west, whereas the maximum AMS axes are oriented nearly north-south and shallowly inclined. At the top of the decollement, the minimum AMS axes orientations abruptly change to nearly vertical; this orientation is maintained throughout the decollement and in the underthrust sediments below. The AMS orientations in the prism sediments above the decollement are consistent with lateral shortening due to regional tectonic stress, as the minimum axes generally parallel the convergence vector of the subducting South American plate and the maximum axes are trench-parallel. Because the orientations of the AMS axes in deformed sediments usually parallel the orientations of the principal strains, the AMS results indicate that the incremental strain state in the Barbados prism is one dominated by subhorizontal shortening. In contrast, the AMS axes within and below the decollement are consistent with a strain state dominated by vertical shortening (compaction). This abrupt change in AMS orientations at the top of the decollement at Site 948 is a direct manifestation of mechanical decoupling of the off-scraped prism sediments from the underthrust sediments. The decoupling horizon occurs at the top of the decollement zone, coinciding with the location of flowing, high-pressure fluids.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1130/0091-7613(1996)​024〈0127:SDATDO〉​2.3.CO;2
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Unveiling the fault source of the January 25th 2016, Mw 6.4 earthquake (Alboran Sea) constrained by seismological and geological data (2017)
    In:  [Poster] In: Subduction Interface Processes SIP 2017, 19.04-21.04.2017, Castelldefels, Barcelona, Spain .
    Details
    Publication Date: 2018-05-31
    Description: On the 25th January 2016 a magnitude Mw 6.3 earthquake struck 45 km offshore north Morocco, the largest recorded event in the Alboran Sea (western Mediterranean). It was preceded on 21 January by an earthquake of magnitude 5.1 in the same epicentral area, and was followed by numerous aftershocks whose locations mainly migrated south and northeast from the mainshock. The mainshock nucleated at a releasing bend of the poorly known Al-Idrissi Fault. According to slip inversion we assume a 20 to maximum 30 km long rupture zone. We use swath-bathymetry, seismic reflection profiles and seismological data to characterize and document Quaternary activity on the 100 km long Al-Idrissi Fault. We report evidence of left-lateral strike-slip displacement, characterize their fault segments and demonstrate that Al-Idrissi is the fault source of the 2016 earthquake events. Located along a crustal boundary that separates the West and East Alboran Sea, the Al-Idrissi Fault is a young structure. Its central segment, mainly transpressive, was developed during the Early Pliocene while the north and south segments are transtensional and of Quaternary age. All these observations together suggest that the Mw 6.4 earthquake broke across the southern and central segment boundary. Therefore, the complete rupture of the Al-Idrissi Fault should be considered and might generate a greater rupture (Mw 7.2), significantly increasing the potential hazard of the structure.
    Type: Conference or Workshop Item , NonPeerReviewed
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    OceanRep: Poster
  • 5
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    Insights on continental collisional processes from GPS data: Dynamics of the peri-Adriatic belts (2018)
    Details
    Publication Date: 2022-04-05
    Description: We present a new GPS velocity field covering the peri-Adriatic tectonically active belts and the entire Balkan Peninsula. From the velocities, we calculate consistent strain rate and interpolated velocity fields. Significant features of the crustal deformation include (1) the eastward motion of the northern part of the Eastern Alps together with part the Alpine foreland and Bohemian Massif toward the Pannonian Basin, (2) shortening across the Dinarides, (3) a clockwise rotation of the Albanides-Hellenides, and (4) a southward motion south of 44°N of the inner Balkan lithosphere between the rigid Apulia and Black Sea, toward the Aegean domain. Using this new velocity field, we derive the strain rate tensor to analyze the regional style of the deformation. Then, we devise a simple test based on the momentum balance equation, to investigate the role of horizontal gradients of gravitational potential energy in driving the deformation in the peri-Adriatic tectonically active mountain belts: the Eastern Alps, the Dinarides, the Albanides, and the Apennines. We show that the strain rate fields observed in the Apennines and Albanides are consistent with a fluid, with viscosity η ∼ 3×1021 Pa s, deforming in response to horizontal gradients of gravitational potential energy. Conversely, both the Dinarides and Eastern Alps are probably deforming in response to the North and North-East oriented motion of the Adria-Apulia indenter, respectively, and as a consequence of horizontal lithospheric heterogeneity.
    Description: Published
    Description: 8701–8719
    Description: 1T. Deformazione crostale attiva
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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