scholarly journals Structural variation along the Zagros and the nature of the Dezful Embayment

2011 ◽  
Vol 148 (5-6) ◽  
pp. 911-924 ◽  
Author(s):  
MARK B. ALLEN ◽  
MORTEZA TALEBIAN

AbstractStructure varies along strike in the Zagros fold-and-thrust belt of Iran, which is a principal element in the Arabia–Eurasia continental collision. Pre-collision, Late Cretaceous ophiolite nappes (Kermanshah, Neyriz) and related nappes of deep marine sediments (Radiolarite Series) were emplaced next to two regions (Pusht-e Kuh arc, Fars) which later developed a consistent structural style across the range from the High Zagros Fault to the foreland limit of deformation. The intervening area has a zone of highly imbricated Arabian plate strata (the Bakhtyari Culmination) thrust southwest towards and over a low relief, low elevation region (the Dezful Embayment). There are no ophiolite nappes northeast of the Bakhtyari Culmination. Isopachs reflect these different structural patterns from Late Cretaceous time but not earlier. In Late Cretaceous time the Dezful Embayment recorded less deposition than adjacent areas to the northwest and southeast. In the Palaeogene there was little net difference between the Dezful Embayment and its margins. The Dezful Embayment has been a depocentre since roughly 35 Ma, which is the likely time of initial collision between Arabia and Eurasia. We propose that the syn-collision structure and stratigraphy of the Zagros is therefore strongly influenced by the variation in Late Cretaceous ophiolite emplacement, but the original cause of this variation is not clear.

1984 ◽  
Vol 121 (6) ◽  
pp. 577-587 ◽  
Author(s):  
P. E. R. Lovelock

AbstractThe structure of the northern part of the Arabian platform is reviewed in the light of hitherto unpublished exploration data and the presently accepted kinematic model of plate motion in the region. The Palmyra and Sinjar zones share a common history of development involving two stages of rifting, one in the Triassic–Jurassic and the other during late Cretaceous to early Tertiary times. Deformation of the Palmyra zone during the Mio-Pliocene is attributed to north–south compression on the eastern block of the Dead Sea transcurrent system which occurred after continental collision in the north in southeast Turkey. The asymmetry of the Palmyra zone is believed to result from northward underthrusting along the southern boundary facilitated by the presence of shallow Triassic evaporites. An important NW-SE cross-plate shear zone has been identified, which can be traced for 600 km and which controls the course of the River Euphrates over long distances in Syria and Iraq. Transcurrent motion along this zone resulted in the formation of narrow grabens during the late Cretaceous which were compressed during the Mio-Pliocene. To a large extent, present day structures in the region result from compressional reactivation of old lineaments within the Arabian plate by the transcurrent motion of the Dead Sea fault zone and subsequent continental collision.


GeoArabia ◽  
2006 ◽  
Vol 11 (1) ◽  
pp. 97-140 ◽  
Author(s):  
Jacek B. Filbrandt ◽  
Salah Al-Dhahab ◽  
Abdullah Al-Habsy ◽  
Kester Harris ◽  
John Keating ◽  
...  

ABSTRACT On the basis of structural style and differences in Late Cretaceous evolution, the carbonate platform in northern Oman and the allochthonous wedge comprising deepwater sediments and oceanic crust in the Oman Mountains form distinct structural domains. Imbrication associated with the emplacement of the Semail Ophiolite and predominantly SW-verging thrusting of the Arabian Platform margin culminated in the late early Campanian. The structural grain of NW-trending thrust faults and contractional folds contrasts markedly with the style and grain of the region immediately south of the Oman Mountains (our study area) and implies strong strain partitioning. Kinematic indicators from subsurface data, combined with the age of growth faulting, provide the basis for the interpretation that maximum horizontal stress was oriented NW-SE in this foreland region rather than NE-SW during the Campanian. The dominant tectonic control on the formation of faults is believed to have been an oblique “collision” of the Indian Continent with the Arabian Plate during the Santonian-Campanian. Deformation in this domain was dominated by distributed strike-slip and normal faulting. This period of faulting was significant for two reasons: (1) The faults both enhanced existing structures and formed new traps. They also allowed vertical migration of hydrocarbons from Palaeozoic reservoirs (e.g. Haushi clastic accumulations) into Shu’aiba and Natih carbonates above. Until that time, some 75 Ma ago, oil was retained in Late Palaeozoic and older traps. This period of deformation is a “Critical Event” within the context of Oman’s hydrocarbon distribution.(2) Faults with NNW and WNW orientations that developed at that time appear to be directly associated with important fracture systems that affect the productivity of several giant fields comprising Natih and Shu’aiba carbonate reservoirs (e.g. Lekhwair, Saih Rawl). Following this tectonic event, late Maastrichtian to Palaeocene uplift and erosion in excess of 1,000 m, is recorded by truncation of the Aruma Group and Natih Formation, as well as part of the Shu’aiba Formation below the base Cenozoic unconformity. Seismic velocity and porosity anomalies from Lekhwair field in the northwest to the Huqf-Haushi High in the southeast, provide additional support for the areal distribution of this event. Around the Lekhwair and Dhulaima fields, the circular to elliptical subcrop pattern below this unconformity does not support the notion of a peripheral bulge related to the emplacement of the allochthon. The stress field changed during the late Cenozoic with the opening of the Red Sea and Gulf of Aden, and the collision of the Arabian Plate with the Iranian Plate. NE-SW-oriented maximum horizontal stress during the late Cenozoic led to the formation of major folds resulting in, for example, the surface anticlines over the Natih and Fahud fields as well as causing inversion along the Maradi Fault Zone. This may also have led to the uplift of the Oman Mountains. The regional northerly subsidence caused by crustal loading of the Arabian Plate gently tilted traps during the Pliocene-Pleistocene from Lekhwair to Fahud.


Tectonics ◽  
2021 ◽  
Vol 40 (4) ◽  
Author(s):  
Luke Mahoney ◽  
Richard Stanaway ◽  
Sandra McLaren ◽  
Kevin Hill ◽  
Eric Bergman

2019 ◽  
Vol 34 (1) ◽  
Author(s):  
Tumpal Bernhard Nainggolan ◽  
Said Muhammad Rasidin ◽  
Imam Setiadi

Multiple often and always appear in marine seismic data due to very high acoustic impedance contrasts. These events have undergone more than one reflection. This causes the signal to arrive back at the receiver at an erroneous time, which, in turn, causes false results and can result in data misinterpretation. Several types of multiple suppression have been studied in literature. Methods that attenuate multiples can be classified into three broad categories: deconvolution methods; filtering methods and wavefield prediction subtraction methods. The study area is situated on Seram Sea in between 131°15’E – 132°45’E and 3°0’S – 4°0’S, Seram Trough which is located beneath Seram Sea at northern part of the Banda-Arc – Australian collision zone and currently the site of contraction between Bird’s Head and Seram. This research uses predictive deconvolution and FK-filter to attenuate short period multiple from their move out, then continued by SRME method to predict multiple that cannot be attenuated from previous method, then followed by Radon transform to attenuate multiple that still left and cannot be attenuated by SRME method. The result of each method then compared to each other to see how well multiple attenuated. Predictive deconvolution and F-K filter could not give satisfactory result especially complex area where multiple in dipping event is not periodic, SRME method successfully attenuate multiple especially in near offset multiple without need subsurface information, while SRME method fails to attenuate long offset multiple, combination of SRME method and Radon transform can give satisfactory result with careful selection of the Radon transform parameters because it can obscure some primary reflectors. Based on geological interpretation, Seram Trough is built by dominant structural style of deposited fold and thrust belt. The deposited fold and thrust belt has a complexly fault geometry from western zone until eastern of seismic line.


2021 ◽  
Author(s):  
Wajdi Belkhiria ◽  
Haifa Boussiga ◽  
Imen Hamdi Nasr ◽  
Adnen Amiri ◽  
Mohamed Hédi Inoubli

<p>The Sahel basin in eastern Tunisia has been subject for hydrocarbon exploration since the early fifties. Despite the presence of a working petroleum system in the area, most of the drilled wells were dry or encountered oil shows that failed to give commercial flow rates. A better understanding of the tectono-sedimentary evolution of the Sahel basin is of great importance for future hydrocarbon prospectivity. In this contribution, we present integration of 2D seismic reflection profiles, exploration wells and new acquired gravity data. These subsurface data reveal that the Sahel basin developed as a passive margin during Jurassic-Early Cretaceous times and was later inverted during the Cenozoic Alpine orogeny. The occurrence of Triassic age evaporites and shales deposited during the Pangea breakup played a fundamental role in the structural style and tectono-sedimentary evolution of the study area. Seismic and gravity data revealed jointly important deep-seated extensional faults, almost along E-W and few along NNE–SSW and NW-SE directions, delimiting horsts and grabens structures. These syn-rift extensional faults controlled deposition, facies distribution and thicknesses of the Jurassic and Early cretaceous series. Most of these inherited deep-seated normal and transform faults are ornamented by different types of salt-related structures. The first phase of salt rising was initiated mainly along these syn-extensional faults in the Late Jurassic forming salt domes and continued into the Early and Late Cretaceous leading to salt-related diapir structures. During this period, the salt diapirism was accompanied by the development of salt withdrawal minibasins, characterized important growth strata due the differential subsidence. These areas represent important immediate kitchen areas to the salt-related structures. The later Late Cretaceous - Cenozoic shortening phases induced preferential rejuvenation of the diapiric structures and led to the inversion of former graben/half-graben structures and ultimately to vertical salt welds along salt ridges. These salt structures represent key elements that remains largely undrilled in the Sahel basin. Our results improve the understanding of salt growth in eastern Tunisia and consequently greatly impact the hydrocarbon prospectivity in the area.</p>


2000 ◽  
Vol 37 (9) ◽  
pp. 1259-1273 ◽  
Author(s):  
M E McMechan

Walker Creek fault zone (WCFZ), well exposed in the western Rocky Mountains of central British Columbia near 54°, comprises a 2 km wide zone of variably deformed Neoproterozoic and Cambrian strata in fault-bounded slivers and lozenges. Extensional shear bands, subhorizontal extension lineations, slickensides, mesoscopic shear bands, and other minor structures developed within and immediately adjacent to the fault zone consistently indicate right-lateral displacement. Offset stratigraphic changes in correlative Neoproterozoic strata indicate at least 60 km of right-lateral displacement across the zone. WCFZ is the southern continuation of the Northern Rocky Mountain Trench (NRMT) fault zone. It shows a through going, moderate displacement, strike-slip fault system structurally links the NRMT and the north-central part of the Southern Rocky Mountain Trench. Strike-slip motion on the WCFZ occurred in the Late Cretaceous to Early Eocene at the same time as northeast-directed shortening in the fold-and-thrust belt. Thus, oblique convergence in the eastern part of the south-central Canadian Cordillera was apparently resolved into parallel northwest-striking zones of strike-slip and thrust faulting during the Late Cretaceous to Early Eocene. The change in the net Late Cretaceous to Early Eocene displacement direction for rocks in the Rocky Mountain trenches from north (56-54°N) to northeast (52-49°N) suggests that the disappearance of strike-slip displacement and increase in fold-and-thrust belt shortening in the eastern Cordillera between 56° and 49°N is largely the result of a north-south change in relative plate motion or strain partitioning across the Cordillera, rather than the southward transformation of right-lateral strike-slip displacement on the Tintina - NRMT fault system into compressional deformation.


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