Mineralogy and Geochemistry of Uraniferous Sandstones in Fault Zone at Wadi El Sahu Area, Southwestern Sinai, Egypt: Implications for Provenance, Weathering and Tectonic Setting

2020 ◽  
Author(s):  
Osama R. Sallam ◽  
Hamed I. Mira ◽  
Amira M. El Tohamy ◽  
Abd Elhadi A. Abbas
Keyword(s):  
Fault Zone ◽  
Tectonic Setting ◽  
Southwestern Sinai

scholarly journals An analysis of the factors that control fault zone architecture and the importance of fault orientation relative to regional stress

2020 ◽  
Vol 132 (9-10) ◽  
pp. 2084-2104 ◽  
Author(s):  
John M. Fletcher ◽  
Orlando J. Teran ◽  
Thomas K. Rockwell ◽  
Michael E. Oskin ◽  
Kenneth W. Hudnut ◽  
...  
Keyword(s):  
Normal Stress ◽  
Fault Zone ◽  
High Strain ◽  
Tectonic Setting ◽  
Fault Zones ◽  
Coseismic Slip ◽  
Full Spectrum ◽  
Architectural Styles ◽  
Fault Zone Architecture ◽  
High Normal Stress

Abstract The moment magnitude 7.2 El Mayor–Cucapah (EMC) earthquake of 2010 in northern Baja California, Mexico produced a cascading rupture that propagated through a geometrically diverse network of intersecting faults. These faults have been exhumed from depths of 6–10 km since the late Miocene based on low-temperature thermochronology, synkinematic alteration, and deformational fabrics. Coseismic slip of 1–6 m of the EMC event was accommodated by fault zones that displayed the full spectrum of architectural styles, from simple narrow fault zones (< 100 m in width) that have a single high-strain core, to complex wide fault zones (> 100 m in width) that have multiple anastomosing high-strain cores. As fault zone complexity and width increase the full spectrum of observed widths (20–200 m), coseismic slip becomes more broadly distributed on a greater number of scarps that form wider arrays. Thus, the infinitesimal slip of the surface rupture of a single earthquake strongly replicates many of the fabric elements that were developed during the long-term history of slip on the faults at deeper levels of the seismogenic crust. We find that factors such as protolith, normal stress, and displacement, which control gouge production in laboratory experiments, also affect the architectural complexity of natural faults. Fault zones developed in phyllosilicate-rich metasedimentary gneiss are generally wider and more complex than those developed in quartzo-feldspathic granitoid rocks. We hypothesize that the overall weakness and low strength contrast of faults developed in phyllosilicate rich host rocks leads to strain hardening and formation of broad, multi-stranded fault zones. Fault orientation also strongly affects fault zone complexity, which we find to increase with decreasing fault dip. We attribute this to the higher resolved normal stresses on gently dipping faults assuming a uniform stress field compatible with this extensional tectonic setting. The conditions that permit slip on misoriented surfaces with high normal stress should also produce failure of more optimally oriented slip systems in the fault zone, promoting complex branching and development of multiple high-strain cores. Overall, we find that fault zone architecture need not be strongly affected by differences in the amount of cumulative slip and instead is more strongly controlled by protolith and relative normal stress.

Tectonic setting of kimberlites in the Vilyui-Markhinsky fault zone according to modern data

2021 ◽  
pp. 14-21
Author(s):  
Elena Protsenko ◽  
Nadezhda Shakhurdina
Keyword(s):  
Fault Zone ◽  
Tectonic Setting ◽  
Research Area ◽  
Network Density ◽  
Low Grade ◽  
High Grade ◽  
Lateral Heterogeneity ◽  
Fault Network ◽  
Kimberlite Field

The lateral heterogeneity of the Vilyui-Markha fault zone was determined, the central and western subzones were identified. The high-grade diamondiferous Mir and Nakyn kimberlite fields are confined to the central subzone. The low-grade diamondiferous Syuldyukar kimberlite field is confined to the western subzone of the VilyuiMarkha zone. The analysis of the fault network density in the research area was carried out. It was found that the fault network density increases within the subzones, which characterizes them as increased permeability areas favorable for kimberlite melts uprising. This fact can be another tectonic criterion for setting up diamond prospecting operations.

Contributions of fault gouge mineralogy on aseismic creep of active faults: the East Anatolian Fault (Eastern Turkey) as a case study

2020 ◽  
Author(s):  
Müge Yazıcı ◽  
Mehran Basmenji ◽  
Mehmet Köküm ◽  
Ugur Dogan ◽  
Cengiz Zabcı ◽  
...  
Keyword(s):  
Shear Zone ◽  
Fault Zone ◽  
Eastern Mediterranean ◽  
Tectonic Setting ◽  
Active Faults ◽  
Fault Gouge ◽  
Seismic Gap ◽  
Fault Rocks ◽  
Tunnel Section ◽  
East Anatolian Fault

<p>In the complex tectonic setting of the Eastern Mediterranean, the westward motion of the Anatolian Block is accommodated mainly along its boundary faults, the North Anatolian Shear Zone (NASZ) and the East Anatolian Shear Zone (EASZ). Although there are relatively limited studies on the active tectonics of the EASZ, horizontal slip rate is suggested to be of about 10 mm/yr, using geodetic data. In terms of instrumental and historical seismicity, this sinistral strike-slip fault generated surface rupturing earthquakes along almost its entire length except two segments, Palu in the northeast and Turkoglu in the southwest, creating two seismic gaps on the East Anatolian Fault (EAF), the most prominent member of the EASZ. In spite of the fact that there are some off-fault seismic activities such as the 2010 Kovancılar Earthquake (M 6.1) in the vicinity of Palu Seismic Gap, recent geodetic measurements show significant aseismic creep, almost retaining the full far plate velocity (~10 mm/yr) for about 100 km-long section of the fault. Hence, the region is continuously monitored by various types of techniques, such as GNSS, InSAR, creepmeter, seismology, and high-resolution photogrammetry.</p><p>In addition to monitoring, we investigated the mechanical signature of the creep in the fault zone using fault rocks along the Palu Segment. We collected several samples directly from the deformation zone of the EAF, which makes the boundary between limestones of the Kirkgecit Formation and the chaotic alternation of volcanics, mudstones, and limestones of the Maden Complex, at two locations. The Underground Railway Tunnel Section (39.9504°N, 38.6976°E) is cut by the fault zone where the creep signals are recorded by a creepmeter. The X-Ray Diffraction (XRD) analyses of collected samples of this locality suggest the presence of montmorillonite (smectite group) as the main clay mineral in addition to chlorite-kaolinite with a negligible amount of illite-mica minerals within the fault rocks. This preliminary result suggests a linkage between the creeping and petrophysical properties of fault rocks, which are made of the weak smectite mineral and show no-frictional healing as the expected characteristics of the creep. However, the preliminary analyses of fault gouge samples from the Murat River Section (39.9696°N, 38.7043°E) yield a small amount of smectite group clays. We are going to extend our study at different locations in order to increase the spatial resolution on the relation between the fault rocks and creep motion. This study is supported by the TUBITAK Project no. 118Y435.</p>

The Hospital coal basin (Massif Central, France): relay on the left-lateral strike-slip Argentat fault in relation to the Variscan postorogenic extension

2005 ◽  
Vol 176 (2) ◽  
pp. 151-159
Author(s):  
Jean-Philippe Bellot ◽  
Jean-Yves Roig ◽  
Antonin Genna
Keyword(s):  
Fault Zone ◽  
Cross Sections ◽  
Tectonic Setting ◽  
Regional Scale ◽  
Theoretical Models ◽  
Strike Slip ◽  
Flower Structure ◽  
Coal Basin ◽  
Massif Central ◽  
Lateral Strike Slip

Abstract Structural and microstructural analyses of the Argentat fault, combined with sedimentological and structural analyses of the associated Hospital basin allow us to discuss the tectonic control of coal basins by crustal-scale faults during the late Palaeozoic evolution of the Variscan lithosphere in the French Massif Central. The brittle Argentat fault zone consists of first- and second-order strike-slip faults, with dominant NNW-sinistral faults, NNE-dextral or sinistral faults and secondary ENE-dextral faults. Several experimental and theoretical models explain the observed fault patterns, like en echelon faults, A-type secondary faults, conjugate faults and Riedel shears. Strike-slip faulting is responsible for folding of the metamorphic formations characterized by N-S to NE-SW-trending axis. The regional-scale geometry of brittle faults and associated folds corresponds to a positive flower structure centered on the brittle Argentat fault, combined to a negative flower structure centered on the coal basin. Using tectonic inversion software, we show that these structures result from a left-lateral movement of the brittle Argentat fault in relation to a tectonic regime intermediate between extension and strike-slip, with a horizontal NE-SW to NNE-SSW-trending maximum stretching axis. Detailed map and cross-sections, and sedimentological interpretations of the late Stephanian Hospital basin show the occurrence of intra-basin syn-sedimentary strike-slip faults and progressive overlaying, indicating that sedimentation occurs during left-lateral strike-slip faulting and folding of basement along the Argentat fault. These data are consistent with a model of N-S to NE-SW-trending postorogenic extension proposed to account for the late Carboniferous evolution of the Variscan lithosphere. They also point out the complexity and the variety of structures developed along a regional brittle strike-slip fault zone and the necessity to take into account all the structures and the resulting geometry of the basement in order to better constrain the tectonic setting of intra-continental deposits.

Petrogenesis and tectonic setting of the Huhetaoergai granitic pluton in the northern Ya-Gan Fault zone, northern Alxa, China: constraints from whole-rock geochemistry, zircon U–Pb ages, and Hf isotope compositions

2020 ◽  
Vol 57 (1) ◽  
pp. 56-68
Author(s):  
Fenquan Xie ◽  
Qianhong Wu ◽  
Lidong Wang ◽  
Wenzhou Xiao ◽  
Jingya Cao ◽  
...  
Keyword(s):  
Fault Zone ◽  
Crystallization Process ◽  
Tectonic Setting ◽  
Coarse Grained ◽  
Collision Process ◽  
Data Set ◽  
Granitic Pluton ◽  
Juvenile Crust ◽  
T Values ◽  
Fractional Crystallization Process

This study presents a new data set that contains zircon U–Pb ages, whole-rock geochemistry, and Hf isotopes of the Huhetaoergai granitic pluton in the northern Ya-Gan Fault zone, northern Alxa, China. The Huhetaoergai pluton is composed of medium- to coarse-grained biotite monzogranite and coarse-grained biotite monzogranite with K-feldspar megacrysts, with U–Pb zircon ages of 220.5 ± 1.9 Ma and 226.5 ± 2.4 Ma, respectively. Granitoids are I-type granites with high εHf(t) values (9–11.05). These features indicate that the granitoids were generated from partial melting of juvenile crust and experienced an obvious fractional crystallization process. We speculate that the granitoids of the Huhetaoergai pluton were formed in an intraplate extensional environment during the post-collision process, indicating a crustal stretching and thinning event in the northern Ya-Gan Fault zone.

scholarly journals Cenozoic tectonic evolution of the Ecemiş fault zone and adjacent basins, central Anatolia, Turkey, during the transition from Arabia-Eurasia collision to escape tectonics

Geosphere ◽  
2020 ◽  
Vol 16 (6) ◽  
pp. 1358-1384
Author(s):  
Paul J. Umhoefer ◽  
Stuart N. Thomson ◽  
Côme Lefebvre ◽  
Michael A. Cosca ◽  
Christian Teyssier ◽  
...  
Keyword(s):  
Fault Zone ◽  
Tectonic Evolution ◽  
Tectonic Setting ◽  
Structural Data ◽  
Late Eocene ◽  
Central Anatolia ◽  
Normal Faults ◽  
Profound Change ◽  
Escape Tectonics ◽  
Lateral Offset

Abstract The effects of Arabia-Eurasia collision are recorded in faults, basins, and exhumed metamorphic massifs across eastern and central Anatolia. These faults and basins also preserve evidence of major changes in deformation and associated sedimentary processes along major suture zones including the Inner Tauride suture where it lies along the southern (Ecemiş) segment of the Central Anatolian fault zone. Stratigraphic and structural data from the Ecemiş fault zone, adjacent NE Ulukışla basin, and metamorphic dome (Niğde Massif) record two fundamentally different stages in the Cenozoic tectonic evolution of this part of central Anatolia. The Paleogene sedimentary and volcanic strata of the NE Ulukışla basin (Ecemiş corridor) were deposited in marginal marine to marine environments on the exhuming Niğde Massif and east of it. A late Eocene–Oligocene transpressional stage of deformation involved oblique northward thrusting of older Paleogene strata onto the eastern Niğde Massif and of the eastern massif onto the rest of the massif, reburying the entire massif to >10 km depth and accompanied by left-lateral motion on the Ecemiş fault zone. A profound change in the tectonic setting at the end of the Oligocene produced widespread transtensional deformation across the area west of the Ecemiş fault zone in the Miocene. In this stage, the Ecemiş fault zone had at least 25 km of left-lateral offset. Before and during this faulting episode, the central Tauride Mountains to the east became a source of sediments that were deposited in small Miocene transtensional basins formed on the Eocene–Oligocene thrust belt between the Ecemiş fault zone and the Niğde Massif. Normal faults compatible with SW-directed extension cut across the Niğde Massif and are associated with a second (Miocene) re-exhumation of the Massif. Geochronology and thermochronology indicate that the transtensional stage started at ca. 23–22 Ma, coeval with large and diverse geological and tectonic changes across Anatolia.

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