287 research outputs found
Multiscale structural analysis of an Epiligurian wedge-top basin: insights into the syn- to post-orogenic evolution of the Northern Apennines accretionary wedge (Italy)
Wedge-top basins represent useful tectonic elements for the characterisation of the evolution of their underlying accretionary wedge in space and time, as their final state of deformation sums up the bulk shortening and structural instability conditions of the wedge. Here, we present the geometric and kinematic patterns of deformation structures deforming the wedge-top Epiligurian basins of the Northern Apennines (Italy). Our main goals are to generate an evolutionary model to account for the syn- to post-orogenic evolution of the Epiligurian basins and to infer the building style of the Northern Apennines wedge during continental collision. Mesoscale structural analysis shows that common and widely distributed thrust and normal fault arrays deform the entire Epiligurian stratigraphic succession infilling the broadly E-vergent wedge-top basins. Thrusts are invariably cut by later NW-SE and NE-SW-striking normal and oblique fault systems characterised by fault planes that mutually intersect at all scales to form polygonal patterns. Remote sensing analysis of the tectonic structures affecting the Epiligurian formations confirms the variable orientation of both thrusts and normal faults within the different studied stratigraphic successions. As a whole, results suggest a polyphase tectonic evolution of the Epiligurian wedge-top basins during the widening of the Northern Apennines accretionary wedge towards the foreland by frontal accretion. The recognised main phases are: (i) syn-orogenic compression accommodating overall tectonic transport towards the eastern quadrants; (ii) post-orogenic extension genetically related to the extension of the inner zone of the Northern Apennines; (iii) more recent extension forming collapse-induced normal faults spatially arranged in polygonal patterns
Constraints on upper crustal fluid circulation and seismogenesis from in-situ outcrop quantification of complex fault zone permeability
The permeability of fault zones plays a significant role on the distribution of georesources and on seismogenesis in the brittle upper crust, where both natural and induced seismicity are often associated with fluid migration and overpressure. Detailed models of the permeability structure of fault zones are thus necessary to refine our understanding of natural fluid pathways and of the mechanisms leading to fluid compartmentalization and possible overpressure in the crust. Fault zones commonly contain complex internal architectures defined by the spatial juxtaposition of "brittle structural facies" (BSF), which progressively and continuously form and evolve during faulting and deformation. We present the first systematic in-situ outcrop permeability measurements from a range of BSFs from two architecturally complex fault zones in the Northern Apennines (Italy). A stark spatial heterogeneity of the present-day permeability (up to four orders of magnitude) even for tightly juxtaposed BSFs belonging to the same fault emerges as a key structural and hydraulic feature. Insights from this study allow us to better understand how complex fault architectures steer the 3D hydraulic structure of the brittle upper crust. Fault hydraulic properties, which may change through space but also in time during an orogenesis and/or individual seismic cycles, in turn steer the development of overpressured volumes, where fluid-induced seismogenesis may localize
Linking rock fabric to fibrous mineralisation: a basic tool for the asbestos hazard
In recent years, many studies have addressed the effect on human health caused by asbestos exposures. As asbestos is a group of fibrous minerals that mainly occurs in mafic and ultramafic rocks (ophiolitic sequences), a close relationship between asbestos occurrence and the geological history of host rocks should be expected. By reviewing the existing literature and presenting characteristic examples, it is proposed a direct correspondence exists between the presence of fibrous minerals in ophiolites and the rock fabric systematics due to the combined activity of deformation, metamorphism/metasomatism, and rock/fluid interaction. Understanding the geological factors that may be at the origin of the nucleation/growth of fibrous minerals constitutes a necessary requirement for developing a methodological and analytical procedure to evaluate asbestos hazard (<I>A</I><sub>H</sub>) in the natural prototype (ophiolitic rocks). A parameterisation of the <I>A</I><sub>H</sub> in function of the main geological processes that produce the rock fabric systematics in different tectonic/geodynamic settings is discussed. A geological multidisciplinary approach (based on geological-structural field evidence combined with textural, mineralogical, petrological, and geochemical investigations) is proposed as the prerequisite for the evaluation of <I>A</I><sub>H</sub> in natural environments. This approach, in particular, can provide a robust basis to formulate a procedural protocol finalised to the mitigation of asbestos effects in environments where these effects are still a real threat
Constraints on upper crustal fluid circulation and seismogenesis from in-situ outcrop quantification of complex fault zone permeability
: The permeability of fault zones plays a significant role on the distribution of georesources and on seismogenesis in the brittle upper crust, where both natural and induced seismicity are often associated with fluid migration and overpressure. Detailed models of the permeability structure of fault zones are thus necessary to refine our understanding of natural fluid pathways and of the mechanisms leading to fluid compartmentalization and possible overpressure in the crust. Fault zones commonly contain complex internal architectures defined by the spatial juxtaposition of "brittle structural facies" (BSF), which progressively and continuously form and evolve during faulting and deformation. We present the first systematic in-situ outcrop permeability measurements from a range of BSFs from two architecturally complex fault zones in the Northern Apennines (Italy). A stark spatial heterogeneity of the present-day permeability (up to four orders of magnitude) even for tightly juxtaposed BSFs belonging to the same fault emerges as a key structural and hydraulic feature. Insights from this study allow us to better understand how complex fault architectures steer the 3D hydraulic structure of the brittle upper crust. Fault hydraulic properties, which may change through space but also in time during an orogenesis and/or individual seismic cycles, in turn steer the development of overpressured volumes, where fluid-induced seismogenesis may localize
Local seismic response studies in the north-western portion of the August 24th, 2016 Mw 6.0 earthquake affected area. The case of Visso village (Central Apennines).
In this work, we investigate the possible causes of the differential damaging observed in Visso village (Central Apennines, about 28 km north from the August 24th, 2016 Mw 6.0 earthquake epicenter). Following insights from the available geological cartography at 1:10.000 scale, a preliminary geophysical survey has been performed in the damaged area in order to constrain geometries and extent of the subsoil lithotypes. Then, these results have been used to retrieve a Vs profile close to the most heavily damaged buildings. This latter has been used as input for a numerical analysis aimed at deriving the motion at the ground level in the study area. In particular, a linear equivalent simulation has been performed by means of EERA code and the waveform has been obtained convolving the time history recorded during the August 24th, 2016 mainshock at Spoleto Monteluco (SPM) site. Our preliminary results indicate a possible correlation of damaging to the thickness and shape of the geological units. Nevertheless, further analyses are necessary to highlight any 2D basin and / non- linear soil behaviour effects in order to compare them to the intrinsic buildings vulnerability, according to the EMS98 guidelines
Optimization of anti-proliferative activity using a screening approach with a series of bis-heterocyclic G-quadruplex ligands
Using a phenotypic screening and SAR optimization approach, a phenyl-bis-oxazole derivative has been
identified with anti-proliferative activity, optimized with the use of a panel of cancer cell lines. The lead
compound was synthesized by means of a short and effective two-step synthesis using Pd-catalyzed
direct arylation. The compound stabilizes several quadruplex DNA sequences including a human telomeric
DNA and one from the promoter of the HSP90 gene, although the structure–activity relationships of the
series are not obviously related to the quadruplex binding
Broadband interactive services provided through TV-centric technologies via bidirectional satellite connection
Higgs boson production via vector-like top-partner decays: diphoton or multilepton plus multijets channels at the LHC
We first build a minimal model of vector-like quarks where the dominant Higgs
boson production process at LHC -- the gluon fusion -- can be significantly
suppressed, being motivated by the recent stringent constraints from the search
for direct Higgs production over a wide Higgs mass range. Within this model,
compatible with the present experimental constraints on direct Higgs searches,
we demonstrate that the Higgs () production via a heavy vector-like
top-partner () decay, , , allows to
discover a Higgs boson at the LHC and measure its mass, through the decay
channels or . We also comment on the recent hint
in LHC data from a possible GeV Higgs scalar, in the presence of
heavy vector-like top quarks.Comment: 14 pages, 8 figure
Forming and preserving aragonite in shear zones: First report of blueschist facies metamorphism in the Jabal Akhdar Dome, Oman Mountains
We report the first occurrence of high-pressure metamorphic aragonite in Precambrian
carbonates of the Jabal Akhdar Dome in the Oman Mountains (northern Oman). We propose
a model for both its formation at blueschist facies conditions and its subsequent preservation
to the surface within the tectonic framework of the Late Cretaceous obduction of
the Semail Ophiolite. Aragonite formed at temperature ∼350 °C and pressure ≥0.9 GPa and
is preserved within mylonitic shear zones and in stretched-fiber dilational veins where the
necessary conditions for its formation and preservation, such as plastic strain accommodation,
fluid-enhanced mineralogical reactions, and an anisotropic permeability structure, were
preferentially met with respect to the surrounding rock. High-strain structural domains are
ideal sites to look for and study prograde and retrograde high-pressure metamorphic histories
in deeply subducted and exhumed terrains
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