scholarly journals Effects of transpression on the rocks exposed at the Jhelum Fault Zone in the east of Potwar Basin, Pakistan: implications on the subsurface deformation pattern

2021 ◽  
Author(s):  
Ibrahim Safi ◽  
Gohar Rehman ◽  
Muhammad Yaseen ◽  
Sohail Wahid ◽  
Muhammad Nouman ◽  
...  
Keyword(s):  
Fault Zone ◽  
Stress Component ◽  
Satellite Image ◽  
Fault System ◽  
Deformation Pattern ◽  
The North ◽  
Lateral Extent ◽  
Geological Map ◽  
Potwar Basin ◽  
Well Data

AbstractJhelum Fault is the north–south-oriented major structural lineament originating from the Hazara-Kashmir Syntaxis and extending southwards towards the Mangla Lake. Geographic extent, nature and significance of Jhelum Fault are the subjects which have been approached by different researchers in the past. The previous research provides enough evidence for the presence of Jhelum Fault as well as they discourse its surface extent. None of the previous research addresses the subsurface model of this fault; consequently, its surface extent has been ambiguous and variably reported. The current research takes into account both the surface lineament as well as the subsurface behaviour of the deformed strata to draft the most reasonable depiction of this fault. Field data were coupled with satellite image of 1.5 m ground resolution to produce the geological map of the study area at 1:25,000 scale. The subsurface model was created along four traverse lines by considering the lateral extent of the structures and their shifting trends on the geological map. The stratigraphic package was taken from the nearby hydrocarbon exploratory well data (Missakeswal-01 well of OGDCL) as no rocks older than middle to late Miocene were exposed in the area. The consistent through-going map extents of many faults in the study area prove that faults are playing the major role in the tectonic evolution of the Jhelum Fault Zone. In the subsurface model, the same faults show very little stratigraphic throw, which signify the major stress component to be associated more with wrenching than pure compression. Therefore, most faults in the area are of transpressional nature having dominant lateral component with relatively smaller push towards west on steeply east dipping faults. The model also shows the positive flower structure with dominantly west verging fault system with few east verging back thrusts. The subsurface proposed model shows that the Jhelum Fault is extendible southwards to the Mangla Lake in the subsurface; however, it acts like a continuous shear zone on the surface where there all the shearing is accommodated by tight refolded fold axes. The east–west shortening does not exceed 14.5% which shows smaller compression in the study area. The 3D model further clarifies the model by showing the consistency of the fault system along strike.

Recent and active deformation in the North Evia domain, a diffuse plate boundary between Eurasia and Aegean plates in the Western termination of the North Anatolian Fault. 

2021 ◽  
Author(s):  
Fabien Caroir ◽  
Frank Chanier ◽  
Virginie Gaullier ◽  
Julien Bailleul ◽  
Agnès Maillard-Lenoir ◽  
...  
Keyword(s):  
Fault Zone ◽  
Plate Boundary ◽  
Fault Zones ◽  
North Anatolian Fault ◽  
Fault System ◽  
Eurasian Plate ◽  
Slip Rates ◽  
The North ◽  
South West ◽  
North Aegean

<p>The Anatolia-Aegean microplate is currently extruding toward the South and the South-West. This extrusion is classically attributed to the southward retreat of the Aegean subduction zone together with the northward displacement of the Arabian plate. The displacement of Aegean-Anatolian block relative to Eurasia is accommodated by dextral motion along the North Anatolian Fault (NAF), with current slip rates of about 20 mm/yr. The NAF is propagating westward within the North Aegean domain where it gets separated into two main branches, one of them bordering the North Aegean Trough (NAT). This particular context is responsible for dextral and normal stress regimes between the Aegean plate and the Eurasian plate. South-West of the NAT, there is no identified major faults in the continuity of the NAF major branch and the plate boundary deformation is apparently distributed within a wide domain. This area is characterised by slip rates of 20 to 25 mm/yr relative to Eurasian plate but also by clockwise rotation of about 10° since ca 4 Myr. It constitutes a major extensional area involving three large rift basins: the Corinth Gulf, the Almiros Basin and the Sperchios-North Evia Gulf. The latter develops in the axis of the western termination of the NAT, and is therefore a key area to understand the present-day dynamics and the evolution of deformation within this diffuse plate boundary area.</p><p>Our study is mainly based on new structural data from field analysis and from very high resolution seismic reflexion profiles (Sparker 50-300 Joules) acquired during the WATER survey in July-August 2017 onboard the R/V “Téthys II”, but also on existing data on recent to active tectonics (i.e. earthquakes distribution, focal mechanisms, GPS data, etc.). The results from our new marine data emphasize the structural organisation and the evolution of the deformation within the North Evia region, SW of the NAT.</p><p>The combination of our structural analysis (offshore and onshore data) with available data on active/recent deformation led us to define several structural domains within the North Evia region, at the western termination of the North Anatolian Fault. The North Evia Gulf shows four main fault zones, among them the Central Basin Fault Zone (CBFZ) which is obliquely cross-cutting the rift basin and represents the continuity of the onshore Kamena Vourla - Arkitsa Fault System (KVAFS). Other major fault zones, such as the Aedipsos Politika Fault System (APFS) and the Melouna Fault Zone (MFZ) played an important role in the rift initiation but evolved recently with a left-lateral strike-slip motion. Moreover, our seismic dataset allowed to identify several faults in the Skopelos Basin including a large NW-dipping fault which affects the bathymetry and shows an important total vertical offset (>300m). Finally, we propose an update of the deformation pattern in the North Evia region including two lineaments with dextral motion that extend southwestward the North Anatolian Fault system into the Oreoi Channel and the Skopelos Basin. Moreover, the North Evia Gulf domain is dominated by active N-S extension and sinistral reactivation of former large normal faults.</p>

Transpressional deformation in the mantle below the North Anatolian fault system, Turkey

2020 ◽  
Author(s):  
Basil Tikoff ◽  
Vasili Chatzaras ◽  
Timothy Chapman ◽  
Naomi Barshi ◽  
Ercan Aldanmaz ◽  
...  
Keyword(s):  
Fault Zone ◽  
Electron Backscatter Diffraction ◽  
Preferred Orientation ◽  
North Anatolian Fault ◽  
Mantle Xenoliths ◽  
Fault System ◽  
Alkali Basalts ◽  
Crystallographic Preferred Orientation ◽  
The North ◽  
Backscatter Diffraction

<p>The North Anatolian Fault Zone (NAFZ) is a 1200-km-long, dextral intracontinental transform fault zone, and initiated ca. 13–11 Ma ago.  The NAFZ formed in response to the N-S convergence of the Eurasian and Arabian plates, accommodated by the westward motion of the Anatolia plate relative to Eurasia plate.  Mantle xenoliths were sampled in late Miocene (11.68±0.25 to 6.47±0.47 Ma) alkali basalts and basanites, immediately N of the trace of the North Anatolian fault, and were previously interpreted to sample the mantle portion of the North Anatolian fault/shear zone at depth.  The studied xenoliths are mainly spinel lherzolites and harzburgites.  Equilibration temperatures estimated from two-pyroxene geothermometers range from 775 to 975 °C, while pressures estimated from the Cr in clinopyroxene geobarometer and pseudosection modelling range from 12 to 22 kbar, which correspond to depths of 40–80 km.  We used high‐resolution X-ray computed tomography to quantify the xenolith fabric defined by the 3D shape preferred orientation of spinel grains.  Spinel displays dominantly oblate fabric ellispoids, consistent with flattening strain.  Olivine has two main crystallographic preferred orientation patterns, the axial-[010] and the A-type, determined with electron backscatter diffraction.  The axial-[010] pattern is consistent with the spinel fabric and other microstructures that show flattening strains.  To further constrain the strain path, we analyze the crystallographic vorticity axes in olivine, which show a complex pattern.  Our results are consistent with an interpretation of transpressional deformation in the upper mantle below the NAFZ, during the early stages of the development of the transform system.  Transpressional deformation is consistent with collision-induced, strike-slip extrusion of Anatolia.</p>

Geological mapping of the 1985 Chinese—British Tibetan (Xizang—Qinghai) Plateau Geotraverse route

1988 ◽  
Vol 327 (1594) ◽  
pp. 287-305 ◽  
Keyword(s):  
Strike Slip ◽  
Geological Mapping ◽  
Strike Slip Fault ◽  
Fault System ◽  
Late Triassic ◽  
Clastic Rocks ◽  
The North ◽  
Opposite Sequence ◽  
Geological Map ◽  
Qiangtang Terrane

The 1:500,000 coloured geological map of the traverse route combines observations from the Geotraverse, previous mapping, and interpretation of orbital images. The position of all localities visited by Geotraverse participants and basic geological data collected by them along the traverse route are shown on a set of maps originally drawn at 1:100,000 scale, reproduced on microfiche for this publication. More detailed mapping, beyond a single line of section, was achieved in five separate areas. The relationships between major rock units in these areas, and their significance, are outlined in this paper. Near Gyanco, (Lhasa Terrane) an ophiolite nappe, apparently connected with outcrops of ophiolites in the Banggong Suture about 100 km to the north, was under thrust by a discontinuous slice of Carboniferous—Permian clastic rocks and limestone, contrary to a previous report of the opposite sequence. At Amdo, a compressional left-lateral strike-slip fault zone has modified relationships along the Banggong Suture. Near Wuli, (northern Qiangtang Terrane) limited truncation of Triassic strata at the angular unconformity below Eocene redbeds demonstrates that most of the folding here is of Tertiary age. The map of the nearby Erdaogou region displays strong fold and thrust-shortening of the Eocene redbeds, evidence of significant crustal shortening after the India- Asia collision began. In the Xidatan-Kunlun Pass area, blocks of contrasting Permo—Triassic rocks are separated by east-trending faults. Some of these faults are ductile and of late Triassic — early Jurassic age, others are brittle and part of the Neogene—Quaternary Kunlun leftlateral strike-slip fault system. Some more significant remaining problems that geological mapping might help to solve are discussed briefly, including evidence for a possible additional ophiolitic suture within the Qiangtang Terrane.

scholarly journals Palaeomagnetic evidence for non-rotational deformation along the Nea Anchialos Fault System, Central Greece

1997 ◽  
Vol 40 (4) ◽  
Author(s):  
D. Kondopoulou ◽  
R. Caputo
Keyword(s):  
Hanging Wall ◽  
Fault System ◽  
Deformation Pattern ◽  
Structural Investigations ◽  
The North ◽  
Magnetic Carriers ◽  
Rotational Deformation ◽  
North Aegean ◽  
Almost All ◽  
Paleomagnetic Direction

Four sites in 1.4 Ma old basaltic lavas and two sites in upper Pliocene-lower Quaternary sediments, located both in the hanging-wall and in the footwall blocks of the Nea Anchialos Fault System, have been sampled. This fault system is one of the major E-W trending structures affecting the Thessaly region during Quaternary times.It is possibly connected with the North Aegean Trough to the E and displays recent seismic activity (1980, Volos earthquake). Standard techniques have been used for both field sampling and laboratory analyses. The magnetic carriers were characterised by measuring the thermomagnetic curves, the anisotropy of magnetic susceptibility and the isothermal remanent magnetisation of the samples. Almost all the samples exhibit a reverse polarity. The overall mean paleomagnetic direction is defined by D = 174°, I = –54°, confirming the non-rotational deformation pattern of the Nea Anchialos Fault System as independently inferred from structural investigations.

Strain Partitioning Between the Izmir-Balikesir Transfer Zone and the North Anatolian Fault Zone, NW Turkey

2020 ◽  
Author(s):  
Levent Tosun ◽  
Elif Çakır ◽  
Bora Uzel ◽  
Ökmen Sümer ◽  
Atilla Arda Özacar ◽  
...  
Keyword(s):  
Fault Zone ◽  
Strike Slip ◽  
North Anatolian Fault ◽  
Western Anatolia ◽  
Deformation Pattern ◽  
Strain Partitioning ◽  
North Anatolian Fault Zone ◽  
The North ◽  
Nw Turkey ◽  
Transfer Zone

<p>The present tectonic framework of the Western Anatolia has been dominated by two major deformations. The first one is the product of the slab-edge processes related to the convergence between Eurasian and African plates along with the Aegean-Cyprean subduction system since the Oligocene, and the second one is the westwards escape of Anatolian Block along the North Anatolian Fault Zone (NAFZ) since the late Miocene. The first one resulted in a widespread extensional deformation in the Western Anatolia and the Aegean region and is associated with slab-detachment and slab-tear processes that gave rise to the development of dynamic topography and various core-complexes (e.g., Cyclades and Menderes). Recent studies have shown that the deferential extensional strain between the core complexes in the region has been accommodated by strike-slip dominated transfer zones, the İzmir-Balıkesir Transfer Zone (İBTZ), which developed (sub)parallel to the extension direction and accommodate differential extension and rotational deformation in the region. The second one gave way to the development of a complex strike-slip deformation pattern and an array of pull-apart basin complexes throughout the northern margin of the Anatolian Block. The NAFZ and İBTZ interact around the Balıkesir-Bursa region resulting in a very peculiar deformation style due to partitioning of strain between these major structures.<br>This study aims at unraveling how the strain partitioning operates between İBTZ and NAFZ and to reveal the kinematic constraints that produced the present tectonic scheme in the region. The geometry and kinematics of the faults are determined by analyzing 2773 fault slip data obtained from 49 sites evenly distributed throughout the study area. The preliminary results show that the İzmir-Balıkesir Transfer Zone localized after Miocene with the decoupling of strike-slip faults, and to the episodic exhumation of the metamorphic core complexes. The focal mechanism solutions of the recent earthquakes support this decoupling and manifest the seismic activity of the İBTZ. This study is supported by a Tübitak Project, Grant Number of 117R011.</p>

scholarly journals Near surface structure of the North Anatolian Fault Zone from Rayleigh and Love wave tomography using ambient seismic noise

2018 ◽  
Author(s):  
George Taylor ◽  
Sebastian Rost ◽  
Gregory Houseman ◽  
Gregor Hillers
Keyword(s):  
Phase Velocity ◽  
Fault Zone ◽  
North Anatolian Fault ◽  
Fault System ◽  
Velocity Variation ◽  
S Wave ◽  
North Anatolian Fault Zone ◽  
Near Surface ◽  
The North ◽  
Wave Tomography

Abstract. We use observations of surface waves in the ambient noise field recorded at a dense seismic array to image the North Anatolian Fault Zone (NAFZ) in the region of the 1999 magnitude 7.6 Izmit earthquake in western Turkey. The NAFZ is a major strike slip fault system extending ~ 1200 km across northern Turkey and poses a high level of seismic hazard, particularly to the city of Istanbul. Assuming isotropy, we obtain maps of phase velocity variation using surface wave tomography applied to Rayleigh and Love waves and construct high resolution images of S-wave velocity in the upper 10 km of a 70 km by 30 km region around Lake Sapanca. We observe low S-wave velocities (< 2.5 km s−1) associated with the Adapazari and Pamukova sedimentary basins, as well as the northern branch of the NAFZ. In the Armutlu Block, between the two major branches of the NAFZ, we detect higher velocities (> 3.2 km s−1) associated with a shallow crystalline basement. We measure azimuthal anisotropy in our phase velocity observations, with the fast direction seeming to align with the direction of maximum extension for the region (~ 45°). The signatures of both the northern and southern branches of the NAFZ are clearly associated with strong gradients in seismic velocity that also denote the boundaries of major tectonic units. Our results suggest that the development of the NAFZ has exploited this pre-existing contrast in physical properties.

scholarly journals Seismic investigation of an active ocean–continent transform margin: the interaction between the Swan Islands Fault Zone and the ultraslow-spreading Mid-Cayman Spreading Centre

2019 ◽  
Vol 219 (1) ◽  
pp. 159-184 ◽  
Author(s):  
C Peirce ◽  
A H Robinson ◽  
A M Campbell ◽  
M J Funnell ◽  
I Grevemeyer ◽  
...  
Keyword(s):  
Continental Crust ◽  
Oceanic Crust ◽  
Fault Zone ◽  
Lower Crust ◽  
P Wave ◽  
Fault System ◽  
Transform Fault ◽  
Apparent Lack ◽  
The North ◽  
Transform Margin

SUMMARY The Swan Islands Transform Fault (SITF) marks the southern boundary of the Cayman Trough and the ocean–continent transition of the North American–Caribbean Plate boundary offshore Honduras. The CAYSEIS experiment acquired a 180-km-long seismic refraction and gravity profile across this transform margin, ∼70 km to the west of the Mid-Cayman Spreading Centre (MCSC). This profile shows the crustal structure across a transform fault system that juxtaposes Mesozoic-age continental crust to the south against the ∼10-Myr-old ultraslow spread oceanic crust to the north. Ocean-bottom seismographs were deployed along-profile, and inverse and forward traveltime modelling, supported by gravity analysis, reveals ∼23-km-thick continental crust that has been thinned over a distance of ∼70 km to ∼10 km-thick at the SITF, juxtaposed against ∼4-km-thick oceanic crust. This thinning is primarily accommodated within the lower crust. Since Moho reflections are not widely observed, the 7.0 km s−1 velocity contour is used to define the Moho along-profile. The apparent lack of reflections to the north of the SITF suggests that the Moho is more likely a transition zone between crust and mantle. Where the profile traverses bathymetric highs in the off-axis oceanic crust, higher P-wave velocity is observed at shallow crustal depths. S-wave arrival modelling also reveals elevated velocities at shallow depths, except for crust adjacent to the SITF that would have occupied the inside corner high of the ridge-transform intersection when on axis. We use a Vp/Vs ratio of 1.9 to mark where lithologies of the lower crust and uppermost mantle may be exhumed, and also to locate the upper-to-lower crustal transition, identify relict oceanic core complexes and regions of magmatically formed crust. An elevated Vp/Vs ratio suggests not only that serpentinized peridotite may be exposed at the seafloor in places, but also that seawater has been able to flow deep into the crust and upper mantle over 20–30-km-wide regions which may explain the lack of a distinct Moho. The SITF has higher velocities at shallower depths than observed in the oceanic crust to the north and, at the seabed, it is a relatively wide feature. However, the velocity–depth model subseabed suggests a fault zone no wider than ∼5–10 km, that is mirrored by a narrow seabed depression ∼7500 m deep. Gravity modelling shows that the SITF is also underlain, at &gt;2 km subseabed, by a ∼20-km-wide region of density &gt;3000 kg m−3 that may reflect a broad region of metamorphism. The residual mantle Bouguer anomaly across the survey region, when compared with the bathymetry, suggests that the transform may also have a component of left-lateral trans-tensional displacement that accounts for its apparently broad seabed appearance, and that the focus of magma supply may currently be displaced to the north of the MCSC segment centre. Our results suggest that Swan Islands margin development caused thinning of the adjacent continental crust, and that the adjacent oceanic crust formed in a cool ridge setting, either as a result of reduced mantle upwelling and/or due to fracture enhanced fluid flow.

scholarly journals Historical evidence of faulting in Eastern Anatolia and Northern Syria

1995 ◽  
Vol 38 (3-4) ◽  
Author(s):  
N. N. Ambraseys ◽  
C. P. Melville
Keyword(s):  
Fault Zone ◽  
Historical Data ◽  
Dead Sea ◽  
Fault System ◽  
Eastern Anatolia ◽  
Major Event ◽  
Historical Evidence ◽  
North Anatolian Fault Zone ◽  
The North ◽  
Large Earthquakes

Historical data show that like the North Anatolian fault zone, which was delineated by a series of earthquakes during this century from east to west, so was the conjugate Eastern Anatolian fault zone delineated from the northeast to the southwest by a succession of large earthquakes in earlier times, with a major event at its junction with the Dead Sea fault system. This event was associated with surface faulting and occurred in a region seismically quiescent for nearly two centuries.

scholarly journals Surface mapping, structural modelling and kinematics along the sinistral strike-slip fault zone, NE Potwar, Pakistan

2021 ◽  
Author(s):  
Muhammad Nouman ◽  
Gohar Rehman ◽  
Muhammad Yaseen ◽  
Sohail Wahid ◽  
Ibrahim Safi ◽  
...  
Keyword(s):  
Fault Zone ◽  
Cross Sections ◽  
Strike Slip ◽  
Computer Application ◽  
Deformation Pattern ◽  
Surface Mapping ◽  
Geological Map ◽  
Dip Isogons ◽  
Splay Faults ◽  
Bounding Surfaces

AbstractThis research was carried out to understand the nature of strike-slip Jhelum Fault zone and to propose a model for the surface to subsurface deformation pattern. Field data along with satellite images are used to construct the geological map. Moreover, the subsurface model has been proposed using the mechanism of dip-isogons in computer application which connects points of equal inclination or dip on the outer and inner bounding surfaces of a folded layers. The proposed geological map and subsurface model shows that the Jhelum Fault when propagated in the south from Hazara-Kashmir Syntaxis forms a continuous shear zone on surface with some discontinuous exposure of splay faults rather than exposed as continuous discrete break. Likewise, the subsurface cross sections show that deformation along the fault zone is accumulated by splay faults from the main Jhelum Fault, which forms a positive flower structure with steep north-eastward dips, which is characteristics of strike-slip movement along Jhelum Fault Zone. The vertical stratigraphic throw along these faults shows small offsets and little east–west shortening, indicating that the major slip along the fault is strike slip.

Sense of displacement on the Cobequid–Chedabucto fault system, Nova Scotia, Canada

1987 ◽  
Vol 24 (2) ◽  
pp. 217-223 ◽  
Author(s):  
C. K. Mawer ◽  
J. C. White
Keyword(s):  
Nova Scotia ◽  
Fault Zone ◽  
Shear Bands ◽  
Fault System ◽  
Progressive Development ◽  
The North ◽  
Ductile Shearing ◽  
History Of ◽  
Appalachian Orogen ◽  
Meguma Terrane

The Cobequid–Chedabucto fault system of the Canadian Appalachians is a major anastomosing fault system over 300 km in length. It separates the Meguma Terrane of southern Nova Scotia from the Avalon Terrane to the north. These terranes are distinct tectonic and lithological entities in the Appalachian Orogen. Two areas at either end of this fault system have been examined in detail to determine the sense and history of offset along it. Both areas are situated on major component fault zones of the system, and both exhibit structures due to early intense ductile shearing that are overprinted by semi-brittle to brittle structures caused by later faulting. Along the eastern Chedabucto fault zone (area A), ductile structures were examined. This area is characterized by the progressive development of S–C textures and shear bands, rotated syntectonic porphyroblasts, and asymmetric minor folds, features indicative of and caused by ductile shearing. Along the western Cobequid fault zone (area B), semi-brittle and brittle structures were studied. A distinctive asymmetric geometrical package of faults, self-similar at a variety of scales, is developed throughout this part of the fault system. Ductile and brittle displacement sense (kinematic) indicators at both sites indicate a protracted history of dextral strike-slip movement. No evidence was observed for major sinistral movement.

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