scholarly journals Tectonic escape of Sicily Microplate in the context of Africa-Europe collision

2021 ◽  
Author(s):  
Giulia Penza ◽  
Pietro Paolo Pierantoni ◽  
Chiara Macchiavelli ◽  
Eugenio Turco
Keyword(s):  
Geological Data ◽  
Kinematic Evolution ◽  
Euler Pole ◽  
Geodynamic Processes ◽  
Tectonic Escape ◽  
Lithosphere Thickness ◽  
Sicily Channel ◽  
Seismic Sections ◽  
Recent Earthquakes ◽  
The Right

<p>Sicily is in the centre of an area where complex geodynamic processes work together, these are: the Tyrrhenian-Apennine System evolution, the African-Ionian slab subduction and Africa-Europe collision.</p><p>During the last 5 Ma it was involved in a process of escape towards east-southeast: while on one side Africa acted as an intender pushing toward north, on the other side the fragmentation and retreat of the African-Ionian slab created space to the east.</p><p>The aim of this study is to reconstruct the kinematic evolution of Sicily, here considered as an independent plate starting from 5 Ma ago, and its role in the context of the Tyrrhenian-Apennine system.</p><p>The plates and microplate involved in the evolution are Europe, Africa and Calabria. The boundaries between these and Sicily are the margin of the Sicily microplate and are lithospheric structures known from the literature and identifiable from high resolution bathymetric maps, seismic sections, geodetic data, focal mechanism of recent earthquakes, gravimetric maps, lithosphere thickness maps and so on.</p><p>Briefly the margin between Sicily and Europe is along the Elimi chain, a E-W trending morpho-structure with transpressive kinematics, the margin with Calabria microplate is along the right-lateral Taormina line and the margin with Africa is expressed along the Malta Escarpment, south of Etna Mount, with transpressive kinematics and along the Sicily Channel, where a series of troughs (Pantelleria, Linosa and Malta) were interpreted in literature as pull-apart basins related to a dextral trascurrent zone.</p><p>The Euler pole of rotation between Sicily and Africa was found starting from the structures in the Sicily Channel and using the GPlates software, then we were able to find also Sicily-Europe and Sicily-Calabria poles and the respective velocity vectors and to compare these with the geological data and better refine the model.</p>

scholarly journals Eastward Tectonic Escape of Sicily Microplate: preliminary results

2020 ◽  
Author(s):  
Giulia Penza ◽  
Chiara Macchiavelli ◽  
Pietro Paolo Pierantoni ◽  
Eugenio Turco
Keyword(s):  
Plate Boundaries ◽  
Preliminary Results ◽  
Complex Processes ◽  
Kinematic Evolution ◽  
Euler Pole ◽  
Tectonic Escape ◽  
Lithosphere Thickness ◽  
Sicily Channel ◽  
Seismic Sections ◽  
Recent Earthquakes

<p>The complex processes affecting the Tyrrhenian-Apennine System are inevitably reflected in Sicily, here considered as an independent plate starting from 5 Ma and located between Europe and Africa plates and Calabria microplate.</p><p>In particular the retreat of the Adriatic-Ionian slab and its fragmentation involve Sicily in a process of escape towards east-southeast due to the space that the slab is creating. At the same time Africa acts as an intender during its convergence with the European plate.</p><p>We show here the preliminary results of a study that aims to reconstruct the kinematic evolution of Sicily and its role in the framework of the Tyrrhenian-Apennine System.</p><p>First of all we found the margins of the plate, searching for lithospheric structures that can be considered as plate boundaries, using different types of data (high resolution bathymetric maps, seismic sections, geodetic data, focal mechanism of recent earthquakes, gravimetric maps, lithosphere thickness maps…) together with the literature.</p><p>The margins are:</p><p>-The Sicily Channel, characterized by a series of pull-apart basins related to a dextral trascurrent zone (Sicily-Africa margin);</p><p>-The Malta escarpment and the Taormina Line characterized by transpression (Sicily-Calabria margin);</p><p>-The Drepano-Ustica seamount also characterized by transpression (Sicily Europe margin).</p><p> </p><p>Starting from the structures in the Sicily Channel, we found the Euler pole of rotation between Sicily and Africa using the GPlates software. Thanks to the software we were able to find also Sicily-Europe and Sicily-Calabria poles and the velocity vectors.</p><p>Finally, we compared the Euler poles and the velocity vectors with the geological data, trying the best fit of the two and better refine the model.</p><p> </p><p><strong>Key Words</strong>: Sicily microplate, Sicily Channel, Malta Escarpment, Tyrrhenian-Apennine System.</p>

An analytical model concerning the possible initiation of subduction between the India and Africa plates, caused by the Morondova plume

2020 ◽  
Author(s):  
Bernhard Steinberger ◽  
Douwe van Hinsbergen
Keyword(s):  
Subduction Zones ◽  
Plate Tectonics ◽  
Eastern Mediterranean ◽  
Plate Boundary ◽  
Plate Motion ◽  
Mantle Flow ◽  
Plate Motions ◽  
Subduction Initiation ◽  
Euler Pole ◽  
Geodynamic Processes

<p>Identifying the geodynamic processes that trigger the formation of new subduction zones is key to understand what keeps the plate tectonic cycle going, and how plate tectonics once started. Here we discuss the possibility of plume-induced subduction initiation. Previously, our numerical modeling revealed that mantle upwelling and radial push induced by plume rise may trigger plate motion change, and plate divergence as much as 15-20 My prior to LIP eruption. Here we show that, depending on the geometry of plates, the distribution of cratonic keels and where the plume rises, it may also cause a plate rotation around a pole that is located close to the same plate boundary where the plume head impinges: If that occurs near one end of the plate boundary, an Euler pole of the rotation may form along that plate boundary, with extension on one side, and convergence on the other.  This concept is applied to the India-Africa plate boundary and the Morondova plume, which erupted around 90 Ma, but may have influenced plate motions as early as 105-110 Ma. If there is negligible friction, i.e. there is a pre-existing weak plate boundary, we estimate that the total amount of convergence generated in the northern part of the India-Africa plate boundary can exceed 100 km, which is widely thought to be sufficient to initiate forced, self-sustaining subduction. This may especially occur if the India continental craton acts like an “anchor” causing a comparatively southern location of the rotation pole of the India plate. Geology and paleomagnetism-based reconstructions of subduction initiation below ophiolites from Pakistan, through Oman, to the eastern Mediterranean reveal that E-W convergence around 105 Ma caused forced subduction initiation, and we tentatively postulate that this is triggered by Morondova plume head rise. Whether the timing of this convergence is appropriate to match observations on subduction initiation as early as 105 Ma depends on the timing of plume head arrival, which may predate eruption of the earliest volcanics. It also depends on whether a plume head already can exert substantial torque on the plate while it is still rising – for example, if the plate is coupled to the induced mantle flow by a thick craton.</p>

scholarly journals Submeridional boundary zone in Asia: seismicity, lithosphere structure, and the distribution of convective flows in the upper mantle

2018 ◽  
Vol 9 (3) ◽  
pp. 1007-1023 ◽  
Author(s):  
N. A. Bushenkova ◽  
O. A. Kuchay ◽  
V. V. Chervov
Keyword(s):  
Central Asia ◽  
Upper Mantle ◽  
Convective Flow ◽  
Focal Mechanisms ◽  
Boundary Zone ◽  
Earthquake Focal Mechanisms ◽  
Principal Axes ◽  
Geodynamic Processes ◽  
Lithosphere Thickness ◽  
Velocity Anomalies

The study is focused on the submeridional transregional boundary that stretches as a wide band along 105°E in Central Asia. In modern seismic models, it is traceable to a depth of ~600 km. In the continental area to the west of this boundary, seismic activity is increased. Following the study of the origin of the transregional boundary zone, it becomes possible to assess its contribution to the current geodynamic processes in Asia. This article presents a comprehensive analysis based on comparison of the available data with the results obtained in our study using independent methods. The distribution of earthquakes was analyzed by depth. We revealed a correlation between the characteristics of seismotectonic deformation (STD) reconstructed from earthquake focal mechanisms, the structure of P-velocity anomalies, and the distribution of convection flows in the upper mantle. The pattern of seismic velocity anomalies in the upper mantle was investigated on the basis of the data from the ISC catalogue for the period of 1964–2011. The modeling was carried out for two regional tomographic schemes, using the first arrivals of P-waves from [Koulakov et al., 2002 and PP-phases from [Bushenkova et al., 2002, with the subsequent summation with weight coefficients depending on the distribution of the input data in each scheme. A similar approach was applied in [Koulakov, Bushenkova, 2010 for the territory of Siberia; however, that model only partially covered the submeridional transregional boundary zone and was based on fewer ISC data (until 2001). The parameters of the combined model were used to estimate variations in the lithosphere thickness, which can significantly influence the structure of convection flows in the upper mantle [Chervov et al., 2014; Bushenkova et al., 2014, 2016. The thickness variations were taken into account when setting boundary conditions in the numerical modeling of thermal convection, which followed the algorithm described in [Chervov, Chernykh, 2014. The STD field was reconstructed from the earthquake focal mechanisms (M≥4.6) which occurred in Central Asia in 1976–2017. The analysis shows that the zone, wherein the seismic regime changes, correlates with the band wherein the STD principal axes are turning, the submeridional high/low velocity elongated boundary in the seismotomographic model, as well as with the submeridionally elongated descending convective flow in the upper mantle. Shortening of the STD principal axes is observed in the submeridional direction in the western part and in the sublatitudinal direction in the eastern part of the study area. The directions of the principal axes turn in the 93–105°E zone. It is thus probable that the submeridionally elongated descending convective flow in the upper mantle of this region, which results from the superposition of the lithosphere thickness heterogeneities, is a barrier to propagation of seismically manifested active geodynamic processes caused by lithospheric plates collision.

scholarly journals Hydrogeological functioning of the tablecloth of the Midelt Furrow (High Moulouya, MOROCCO)

2018 ◽  
Vol 37 ◽  
pp. 01002
Author(s):  
H. Ikhmerdi ◽  
A. Boukdir ◽  
A. Kossir ◽  
L. Alili ◽  
E. Ben-Said
Keyword(s):  
Water Quality ◽  
Point Of View ◽  
Flow Mode ◽  
Left Bank ◽  
Geological Data ◽  
The West ◽  
High Atlas ◽  
The Poor ◽  
The Right ◽  
Different Levels

The superficial tablecloth of furrow of Midelt belongs to the bowl of High Moulouya which stretches out from the west eastward between the High Atlas in the South and the Medium Atlas west and in the Northeast. The methodology used includes the synthesis of geological data, piezometry, hydrodynamics, hydroclimatology and water quality. This study provides the following results: The flow mode of the water table is general SW to NE on the left bank of the Moulouya river and on the right bank, the flow is from the NW to the SE. The piezometric ratings vary from 1460 to 1780 m. The hydraulic gradient is the order of 2% on average. The transmissivity is usually about 10-3 m2/s. the punctual flows can reach 50 l / s (case of the drilling N ° IRE 879/38 realized in the alluviums of the Outat). The flow provided by the sources from conglomerates and lake limestones of the Plio-Villafranchien is 50 l / s. The unit of the Mio- Plio-Quaternary aquifer is fed from the infiltrations of rains, by the wadis which cross the banks of the conglomerates and by the landing of the tablecloths of Lias, Dogger and Cretaceous this feeding is however weak in because of the discontinuity of the formations and the poor permeability of the different levels. From a qualitative point of view the groundwater analysis of the aquifer shows that their overall quality is average to good.

Coexisting geodynamic processes in the Sicily Channel

2006 ◽  
Author(s):  
Giacomo Corti ◽  
Marco Cuffaro ◽  
Carlo Doglioni ◽  
Fabrizio Innocenti ◽  
Piero Manetti
Keyword(s):  
Geodynamic Processes ◽  
Sicily Channel

scholarly journals Tectonic inversion of salt-detached ramp-syncline basins as illustrated by analog modeling and kinematic restoration

2018 ◽  
Vol 6 (1) ◽  
pp. T127-T144 ◽  
Author(s):  
Maria Roma ◽  
Oskar Vidal-Royo ◽  
Ken McClay ◽  
Oriol Ferrer ◽  
Josep Anton Muñoz
Keyword(s):  
Cross Sections ◽  
Hanging Wall ◽  
Sedimentary Basins ◽  
Kinematic Evolution ◽  
Analog Modeling ◽  
Tectonic Inversion ◽  
Positive Tectonic Inversion ◽  
Seismic Sections ◽  
And Inversion ◽  
Analog Models

Salt-detached ramp-syncline basins are developed in extensional settings and are characterized by wide synclinal sedimentary basins detached on salt and formed above the hanging wall of active ramp-flat-ramp extensional faults. They are rarely fault bounded; instead, they are bounded by salt structures that are in general parallel to the major subsalt structures. As such, the formation of these extensional systems requires the presence of (1) a subsalt extensional fault with significant dip changes and (2) an evaporitic unit above the extensional fault, which partially or completely decouples the basin from a subsalt extensional fault. Salt-detached ramp-syncline basins have a significant exploration potential when their extensional geometry is preserved and when they have undergone positive tectonic inversion and consequent uplift and fold amplification. However, in some cases, their subsalt geometry may not be fully recognizable, especially when subsalt seismic imaging is poor. To obtain a deeper understanding of the geometry and kinematic evolution of these salt-detached ramp-syncline basins, we performed a series of analog modeling experiments, in which the models’ cross sections had been sequentially restored. Analog models and restoration results reveal that the kinematic evolution of the salt-detached ramp-syncline basins during extension and inversion depends on the interaction of different factors that may function simultaneously. Our results are used to improve the interpretation of seismic sections in inverted Mesozoic salt-detached ramp-syncline basins on the Atlantic margins, where subsalt faults are not well-imaged, and thus the suprasalt geometries must be used to infer the subsalt structure.

scholarly journals The results of dipole sounding of the right bank of the dam of the Chirkei hydroelectric power plant

2019 ◽  
Vol 12 (2) ◽  
pp. 113-119
Author(s):  
Sh. G. Idarmachev ◽  
Ib. S. Idarmachev
Keyword(s):  
Rock Mass ◽  
Power Plant ◽  
Power Plants ◽  
Hydroelectric Power Plant ◽  
Hydroelectric Power ◽  
Geological Processes ◽  
Accuracy Of Measurements ◽  
Short Period ◽  
Geodynamic Processes ◽  
The Right

For the first time in the practice of full-scale studies in the area of the Chirkei HPP dam, the method of dipole electric sounding was used. The aim was to study the geodynamic processes in the rock mass located in the sides of the highrise dam to develop new methods of control of natural and man-made hazardous geological processes. The basis for the study of deformation processes in a large volume of the right bank of the dam was laid by the results of electric sounding of rocks by a small four-electrode in-well installation over the period 2010–2015, which showed that the change in the level of the reservoir caused seasonal deformation of rocks. The use of dipole sounding can significantly increase the size of the object under study. The volume of the probed rocks of the right bank of the dam is 6×106 m3, that is 2000 times larger compared to the four-electrode in-well installation. The equipment used is characterized by the continuity and high accuracy of measurements of apparent resistance of the mass, which enables to register the dynamic processes occurring in it. The results of observations by the method of dipole sounding over a short period of 2018 enable to conclude about the anthropogenic impact of the Chirkei hydroelectric power plant on the stress-strain state of rocks adjacent to the right side of the dam. For individual periods of observation, variations of apparent resistivity of large amplitude are detected, suggesting that the analyzed mass is in conditions of unstable equilibrium, i. e. displacements occur from time to time along the cracks in place. The movements can be triggered by starts of hydraulic units. Shifts in large tectonic cracks in the rock mass near the right side of the dam can lead to landslide processes and opening of cracks in the dam contact zone. The method of continuous dipole electric sounding can find its practical application for monitoring of hazardous geological processes in hydroelectric power plants.

Geo-Hydrodynamic Risk Management: Villano-Baeza Pipeline System

2021 ◽  
Author(s):  
Fabián Vásconez ◽  
Alberto Velasteguí ◽  
Jaime Núñez ◽  
Patricio Torres ◽  
Paco Riofrío ◽  
...  
Keyword(s):  
Oil Spills ◽  
Monitoring Program ◽  
Pipeline System ◽  
Second Phase ◽  
Periodic Review ◽  
Oil Pipeline ◽  
Geodynamic Processes ◽  
Multi Temporal ◽  
Geophysical Investigations ◽  
The Right

Abstract The main areas susceptible to the occurrence of landslides, which imply a threat against the pipeline system, are identified, mapped and classified according to their degree of danger, for which the kinematics of each landslide is considered its intensity and probability of occurrence. In a second phase, detailed geological, geotechnical and geophysical investigations of the main landslides, both active and potential, are carried out. A monitoring program of the unstable slopes through inclinometers, piezometers, strain-gauges, crack meters is carried out in order to determine the degree of activity of the landslides. Among the monitoring techniques, PCM (Pipeline Current Mapper) has been incorporated. Additionally, a record and analysis of trigger factors such as rainfall and seismic activity is carried out. As an additional control system, periodic review of multi-temporal satellite images has been incorporated, which provides a macro vision of the evolution of geodynamic, hydrodynamic and anthropic processes that could affect the integrity of the pipeline any time. Of importance for management is the work of preventive maintenance of the Right of Way, trying to identify and manage the geodynamic processes in a timely manner, before they become uncontrollable. As a result, we have an Oil Pipeline System that has not suffered any rupture, and without consequently oil spills, in more than 21 years of operation.

Sign in / Sign up

Export Citation Format

Share Document