Deformation pattern in the underthrust carbonate-rich sequence of the Sibillini Thrust (central Italy): insights for shear zone evolution in modern subduction complexes

2007 ◽  
Vol 20 (1-2) ◽  
pp. 53-69 ◽  
Author(s):  
Lorenzo Leoni ◽  
Paola Vannucchi ◽  
Gianfranco Principi ◽  
Filippo Catani
Keyword(s):  
Shear Zone ◽  
Central Italy ◽  
Deformation Pattern

Mesostructural analysis of S-C fabrics in a shallow shear zone of the Umbria–Marche Apennines (Central Italy)

2014 ◽  
Vol 409 (1) ◽  
pp. 149-166 ◽  
Author(s):  
G. Lena ◽  
M. R. Barchi ◽  
W. Alvarez ◽  
F. Felici ◽  
G. Minelli
Keyword(s):  
Shear Zone ◽  
Central Italy ◽  
Mesostructural Analysis

scholarly journals Morphostructural, Meteorological and Seismic Factors Controlling Landslides in Weak Rocks: The Case Studies of Castelnuovo and Ponzano (North East Abruzzo, Central Italy)

Geosciences ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 122 ◽  
Author(s):  
Monia Calista ◽  
Enrico Miccadei ◽  
Tommaso Piacentini ◽  
Nicola Sciarra
Keyword(s):  
Central Italy ◽  
Alluvial Fan ◽  
Precipitation Event ◽  
Integrated Analysis ◽  
Deformation Pattern ◽  
Weak Rocks ◽  
Geomorphological Mapping ◽  
North East ◽  
Triggering Factors ◽  
The Stability

We investigated the role of the morphostructural setting and seismic and meteorological factors in the development of landslides in the piedmont of the Abruzzo Apennines. In February 2017, following a heavy snow precipitation event and a moderate seismic sequence (at the end of the Central Italy 2016–2017 seismic crisis), several landslides affected the NE-Abruzzo chain and piedmont area. This work is focused on the Ponzano landslide (Civitella del Tronto, Teramo) and the Castelnuovo landslide (Campli, Teramo) in the NE Abruzzo hilly piedmont. These landslides consist of: (1) a large translational slide-complex landslide, affecting the Miocene–Pliocene sandstone clay bedrock sequence of the piedmont hilly sector; and (2) a complex (topple/fall-slide) landslide, which occurred along a high and steep scarp on conglomerate rocks pertaining to terraced alluvial fan deposits of the Pleistocene superficial deposits. Both of the landslides are typical of the Abruzzo hilly piedmont and both of them largely affected houses and villages located on top of the scarp or within the slope. The landslides were studied by means of field geological and geomorphological mapping, borehole investigations, geostructural analysis and photogeological analysis. For the Ponzano landslide, a detail pre-post-landslide air photo interpretation allowed for defining the deformation pattern occurred on the slope. For the Castelnuovo landslide, the triggering factors and the stability of the slope were evaluated with FLAC3D numerical modelling, in pre- and post-landslide conditions. Through this integrated analysis, the triggering factors, the landslide mechanism and the stability conditions of the landslides and the characterization of two main types of landslides affecting the piedmont hilly area of the Abruzzo region were investigated.

scholarly journals Eburnean deformation pattern of Burkina Faso and the tectonic significance of shear zones in the West African craton

2020 ◽  
Vol 191 ◽  
pp. 2 ◽  
Author(s):  
Dominique Chardon ◽  
Ousmane Bamba ◽  
Kalidou Traoré
Keyword(s):  
Burkina Faso ◽  
Shear Zone ◽  
Regional Scale ◽  
Kinematic Model ◽  
Shear Zones ◽  
West African ◽  
Deformation Pattern ◽  
The West ◽  
West African Craton ◽  
Regional Flow

Shear zones of the Paleoproterozoic Eburnean accretionary Orogen (West African craton) are investigated by means of large-scale structural mapping. Regional scale (10-100 km) mapping was based on the aeromagnetic survey of Burkina Faso and craton-scale (1000 km) mapping on a compilation of fabric data. At both scales, shear zones are arranged as an anastomosed transpressional network that accommodated distributed shortening and lateral flow of the orogenic lithosphere between the converging Kénéma-Man and Congo Archean provinces. Structural interference patterns at both scales were due to three-dimensional partitioning of progressive transpressional deformation and interactions among shear zones that absorbed heterogeneities in the regional flow patterns while maintaining the connectivity of the shear zone network. Such orogen-scale kinematic patterns call for caution in using the deformation phase approach without considering the “bigger structural picture” and interpreting displacement history of individual shear zones in terms of plate kinematics. The West African shear zone pattern is linked to that of the Guiana shield through a new transatlantic correlation to produce an integrated kinematic model of the Eburnean-Transamazonian orogen.

Ductile-brittle shear zone in a listwaenite body, within the Frontal Range Fault of the Oman Mountains (Sultanate of Oman)

2020 ◽  
Author(s):  
Andreas Scharf ◽  
Frank Mattern ◽  
Paul Mattern
Keyword(s):  
Shear Zone ◽  
Oceanic Lithosphere ◽  
Late Eocene ◽  
Age Dating ◽  
Deformation Pattern ◽  
Sultanate Of Oman ◽  
Brittle Deformation ◽  
Northern Margin ◽  
Oman Mountains ◽  
Semail Ophiolite

<p>Listwaenite (fully serpentinized and carbonatized/silicified ultramafic rock) is common within the Oman Mountains near Fanja. The Oman Mountains formed during the late Cretaceous obduction of the Semail Ophiolite. Eventually, major exhumation and associated extensional shearing formed the Saih Hatat Dome during the latest Cretaceous to Paleocene. This dome displays rocks of the Arabian platform, framed by the Hawasina Allochthonous and the Semail Ophiolite. Postobductional rapid exhumation/cooling of the Saih Hatat Dome is reflected by a major extensional shear zone at the northern margin of the dome (Frontal Range Fault, FRF; Mattern and Scharf, 2018). Shearing along the FRF with a throw of few to several kilometers, occurred within two intervals. The major first event occurred during the latest Cretaceous to Paleocene while the minor second event lasted probably from the late Eocene to Oligocene (Mattern et al., 2019). Along and within the FRF, major tabular listwaenite bodies occur displaying a lateral extend from few meters to hundreds of meters and a thickness of up to a few to tens of meters. According to Scharf et al. (2020), the listwaenite dates as latest Cretaceous to Paleocene.</p><p>Most of the numerous SiO<sub>2</sub>-rich listwaenite bodies near Fanja preserve a brittle deformation pattern, indicating that the temperature during and after formation was less than 250°C. As an exception, we found one unusually well-developed, intensely foliated and wide strike-slip ductile-brittle shear zone at the surface, exhibiting a width of 5m and a length of a few tens of meters within a large listwaenite body near the community of Sunub. The foliation of the shear zone dips to the SW with about 50-80°. The shear zone intersects at a high angle with the FRF (strike SW-NE) and the listwaenite unit it contains. The shear movement is unrelated to that of the FRF. Approximately 6km WNW of the sheared listwaenite, a mafic dike of Lutetian age (42.7±0.5Ma; Mattern et al., 2019) intruded Cenozoic limestone. Intrusion is associated with the second shearing interval of the FRF. Because listwaenite bodies usually display brittle deformation, we tentatively conclude that the ductile-brittle shear zone formed during the late Eocene because of mafic intrusions. We assume that another mafic body is located near the shear zone and provided the heat for the ductile-brittle deformation conditions.</p><p> </p><p>References:</p><p>Mattern, F., Scharf, A., 2018. Postobductional extension along and within the Frontal Range of the Eastern Oman Mountains. Journal of Asian Earth Sciences 154, 369-385, doi: 10.1016/j.jseaes.2017.12.031.</p><p>Mattern, F., Sudo, M., Callegari, I., Pracejus, B., Bauer, W., Scharf, A., 2019. Late Lutetian <sup>40</sup>Ar/<sup>39</sup>Ar Age Dating of a Mafic Intrusion into the Jafnayn Formation and its Tectonic Implications (Muscat, Oman). AAPG Event, 2<sup>nd</sup> Edition, Structural styles of the Middle East, 9<sup>th</sup>-11<sup>th</sup> December 2019, Muscat, Oman.</p><p>Scharf, A., Mattern, F., Bolhar, R., Bailey, C.M., Ring, U., 2020. U-Pb dating of postobductional carbonate veins in listwaenite of the Oman Mountains near Fanja. International Conference on Ophiolites and the Oceanic Lithosphere: Results of the Oman Drilling Project and Related Research, 12-14<sup>th</sup> January, 2020, Sultan Qaboos University, Muscat, Sultanate of Oman.</p>

The Stress-State in the Shear Zone During Steady State Machining

1979 ◽  
Vol 101 (2) ◽  
pp. 211-216 ◽  
Author(s):  
J. H. L. The´ ◽  
R. F. Scrutton
Keyword(s):  
Flow Stress ◽  
Stress State ◽  
Strain Rate ◽  
Shear Zone ◽  
Deformation Mode ◽  
Deformation Pattern ◽  
Line Field ◽  
Strain And Strain Rate ◽  
Theoretical Predictions ◽  
Simple Shear Deformation

In order to calculate the stress state at any point in the shear zone, a new method has been developed which incorporates the effects of strain—hardening, strain-rate and temperature. Previous attempts have employed a modified slip-line field technique. The method is based on an empirical formula derived from published experimental data over a period of fifteen years relating flow stress values with values of strain, strain-rate, and temperature. From an experimentally derived deformation pattern, the strain and strain-rate distributions may be determined assuming a simple shear deformation mode. By using the empirical flow stress formula, the stresses and temperatures in the plastic zone may be calculated easily. Theoretical predictions agree well with experimentally observed values. The method is applied to a parallel-sided zone.

scholarly journals Deformation Characteristics of the Shear Zone and Movement of Block Stones in Soil–Rock Mixtures Based on Large-Sized Shear Test

2020 ◽  
Vol 10 (18) ◽  
pp. 6475
Author(s):  
Zhiqing Li ◽  
Feng Hu ◽  
Shengwen Qi ◽  
Ruilin Hu ◽  
Yingxin Zhou ◽  
...  
Keyword(s):  
Shear Deformation ◽  
Shear Zone ◽  
Failure Mode ◽  
Deformation Pattern ◽  
Deformation Characteristics ◽  
Shear Surface ◽  
Field Samples ◽  
Deformation Properties ◽  
Shear Process ◽  
Zone Deformation

Soil–rock mixtures (SRM) have the characteristics of distinct heterogeneity and an obvious structural effect, which make their physical and mechanical properties very complex. This study aimed to investigate the deformation properties and failure mode of the shear zone as well as the movement of block stones in SRM experimentally, not only considering SRM shear strength. The particle composition and proportion of specimens were based on field samples from an SRM slope along national highway 318 in Xigaze, Tibet. Shear zone deformation tests were carried out using an SRM-1000 large-sized geotechnical apparatus controlled by a motor servo, considering the effects of different stone contents by mass (0, 30%, 50%, 70%), vertical pressures (50, 100, 200, 300, and 400 kPa), and block stone sizes (9.5–19.0, 19.0–31.5, and 31.5–53.0 mm). The characteristics of the shear zone deformation and block stone interactions were monitored by placing aluminum wires and dry ash in holes in the specimens. The results showed that the stone content 30% and 70% were two critical thresholds to determine the deformation characteristics of SRM. Under the conditions of high stone content and large particle size, the stones throughout the shear surface tended to extrude and roll during the shear process. The block stones around the shear surface were mainly affected by dilatancy and exhibited extrusion, particle breakage, and redistribution. The deformation pattern could be considered as be analogous to push-type shear deformation from the back to front or composite shear deformation from the front and back to the middle of the slope. It is of great importance to study the shear characteristics and deformation evolution of SRM to understand the progressive shear process of the sliding zone and the failure mode of landslides.

scholarly journals Deformation pattern of the 6 and 7 April 2009, <i>M</i><sub>W</sub>=6.3 and <i>M</i><sub>W</sub>=5.6 earthquakes in L'Aquila (Central Italy) revealed by ground and space based observations

2010 ◽  
Vol 10 (1) ◽  
pp. 73-87 ◽  
Author(s):  
I. D. Papanikolaou ◽  
M. Foumelis ◽  
I. Parcharidis ◽  
E. L. Lekkas ◽  
I. G. Fountoulis
Keyword(s):  
Environmental Effects ◽  
Central Italy ◽  
Deformation Pattern ◽  
Fault Surface ◽  
The Past ◽  
Order Of Magnitude ◽  
Surface Ruptures ◽  
Maximum Subsidence ◽  
Fault Trace ◽  
Earthquake Environmental Effects

Abstract. The deformation pattern of the 6 and 7 April 2009 MW=6.3 and MW=5.6 earthquakes in L'Aquila is revealed by DInSAR analysis and compared with earthquake environmental effects. The DInSAR predicted fault surface ruptures coincide with localities where surface ruptures have been observed in the field, confirming that the ruptures observed near Paganica village are indeed primary. These ruptures are almost one order of magnitude lower than the ruptures that have been produced by other major surrounding faults in the past. These faults have not been activated during the 2009 event, but have the capacity to generate significantly stronger events. DInSAR analysis shows that 66% (or 305 km2) of the area deformed has been subsided whereas the remaining 34% (or 155 km2) has been uplifted. A footwall uplift versus hangingwall subsidence ratio of about 1/3 is extracted from the mainshock. The maximum subsidence (25 cm) was recorded about 4.5 km away from the primary surface ruptures and about 9 km away from the epicentre. In the immediate hangingwall, subsidence did not exceeded 15 cm, showing that the maximum subsidence is not recorded near the ruptured fault trace, but closer to the hangingwall centre. The deformation pattern is asymmetrical expanding significantly towards the southeast. A part of this asymmetry can be attributed to the contribution of the 7 April event in the deformation field.

Post-seismic deformation related to the 2016 central Italy seismic sequence from GPS displacement time-series

2021 ◽  
Author(s):  
Eugenio Mandler ◽  
Maria Elina Belardinelli ◽  
Enrico Serpelloni ◽  
Letizia Anderlini ◽  
Adriano Gualandi ◽  
...  
Keyword(s):  
Time Series ◽  
Shear Zone ◽  
Central Italy ◽  
Transient Signal ◽  
Driving Mechanism ◽  
Far Field ◽  
Crust And Upper Mantle ◽  
Epicentral Area ◽  
Brittle Ductile Transition ◽  
Seismic Deformation

&lt;p&gt;The 2016-2017 Central Italy earthquake sequence was characterized by three main events striking the central Apennines between August 2016 and October 2016 with a Mw &amp;#8712; [5.9 to 6.5], plus four earthquakes occurring in January 2017 with a Mw &amp;#8712; [5.0; 5.5]. Here we study 85 Global Positioning System (GPS) stations active during the post-seismic phase in a region within a radius of 100 km around the epicentral area, including near and far-field domains. We separate the post-seismic deformation from other, mainly seasonal, deformation signals present in ground displacement time-series via a variational Bayesian Independent Component Analysis (vbICA) technique. Excluding the postseismic transient signal, we found that all the other components are due to hydrological processes, and found no evidence of pre-seismic deformation signals with a spatial and temporal pattern that can be ascribed to a precursory deformation. We study the role played by afterslip on the main structures activated during the co-seismic phase, and we infer the activation during the post-seismic phase of the Paganica fault, which is located further south of the 2016-2017 epicenters and did not rupture during the co-seismic phase. We investigate an aseismic activation of the &amp;#8764; 2 &amp;#8722; 3 km thick subhorizontal layer of seismicity, which bounds at depth the SW-dipping normal faults where the mainshocks nucleated, and which has been interpreted as a shear zone. Moreover we consider the possibility that the shear zone marks the brittle-ductile transition including the viscoelastic relaxation of the lower crust and upper mantle as a driving mechanism of the post-seismic displacement. However, neither afterslip nor viscoelasticity can fully explain the observations alone: the former is capable of satisfactorily explaining only the data in the epicentral area but it generally underestimates the displacement in the far-field domain; the latter cannot simultaneously explain the displacement observed in the near-field and far-field domains. Hence we infer a mixed contribution of these two mechanisms.&amp;#160;&lt;/p&gt;

scholarly journals Surface faulting during the August 24, 2016, Central Italy earthquake (Mw 6.0): preliminary results

2016 ◽  
Vol 59 ◽  
Author(s):  
Franz A. Livio ◽  
A. M. Michetti ◽  
E. Vittori ◽  
L. Gregory ◽  
L. Wedmore ◽  
...  
Keyword(s):  
Central Italy ◽  
Surface Expression ◽  
Deformation Pattern ◽  
Complex Deformation ◽  
Fault Surface ◽  
Preliminary Results ◽  
The North ◽  
Central Italy Earthquake ◽  
Seismogenic Source ◽  
Adjacent Structures

<p>We present some preliminary results on the mapping of coseismically-induced ground ruptures following the Aug. 24, 2016, Central Italy earthquake (Mw 6.0). The seismogenic source, as highlighted by InSAR and seismological data, ruptured across two adjacent structures: the Vettore and Laga faults. We collected field data on ground breaks along the whole deformed area and two different scenarios of on-fault coseismic displacement arise from these observations. To the north, along the Vettore fault, surface faulting can be mapped quite continuously along a well-defined fault strand while such features are almost absent to the south, along the Laga fault, where flysch-like marly units are present. A major lithological control, affects the surface expression of faulting, resulting in a complex deformation pattern.</p>

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