scholarly journals Geology and Structural Description of Shakrok Anticline; Northern Iraq

2020 ◽  
pp. 2017-2032
Author(s):  
Mahmood Abd ALAmeer Salman ◽  
Sally Hussin Ahmed
Keyword(s):  
High Stress ◽  
Arabian Plate ◽  
Structural Description ◽  
Fold Axis ◽  
Northern Iraq ◽  
Anticlockwise Rotation ◽  
Major Fault ◽  
Tertiary Folding ◽  
Folded Structures ◽  
Stratigraphic Succession

The studied area is a part of the Arabian plate located within the High Folded Zone of the Zagros Fold-Thrust Belt in northeastern Iraq (Kurdistan Region). The Study area deals with the Shakrok Anticlines is located between Safin Mountain and Sork Mountain. These structures are formed during the Alpine Orogeny in Cretaceous-Tertiary period. Generally, the folded structures are trending NW-SE direction which is parallel to the main Zagros Orogenic trends. The exposed stratigraphic succession of the studied area that represented by 4 formations deposited from the Early Cretaceous which are Shiranish, Aqrah, Bekhme and Qamchuqa formations. Shakrok Anticline are asymmetrical, double plunging and verging toward northeast. This establishes that Merawa is a Tertiary continuation part of Cretaceous Shakrok Anticline, but there is a deflection in the direction of the fold axis that affected the Merawa Anticline due to the effect of strike slip fault addition to Lineament. Shakrok Anticline with Cretaceous successions formed due to the effect of Cretaceous and Tertiary folding phases. But Merawa Anticline with Tertiary succession that formed due to the effect of Tertiary folding phases. The high stress and intensity of the major fault on the southwestern limb rotated and overturned Tertiary successions and changed its dip toward NE. The differences in fold geometry, fold axis, axial surface, and curvilinear hinge imply that the structure formed as a result of two folding phases & lateral growth of folds that developed by changing the direction of the compressional tectonic processes due to Alpine Orogene of Zagros. The fold axis of Shakrok Anticline rotated 16o in anticlockwise trend from Merawa to Sork anticlines. Because of anticlockwise rotation of the Arabian plate due to its collision with Iranian and Anatolian plates.

scholarly journals Kinematics of subduction in the Ibero-Armorican arc constrained by 3D microstructural analysis of garnet and pseudomorphed lawsonite porphyroblasts from Île de Groix (Variscan belt)

Solid Earth ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 971-992
Author(s):  
Domingo G. A. M. Aerden ◽  
Alejandro Ruiz-Fuentes ◽  
Mohammad Sayab ◽  
Aidan Forde
Keyword(s):  
Microstructural Analysis ◽  
Small Island ◽  
Lower Grade ◽  
Fold Axis ◽  
Thin Sections ◽  
Anticlockwise Rotation ◽  
Strong Resemblance ◽  
Inclusion Trails ◽  
Shaped Inclusion ◽  
Cylindrical Folds

Abstract. The small island of Groix in southern Brittany, France, is well known for exceptionally well-preserved outcrops of Variscan blueschists, eclogites, and garnetiferous mica schists that mark a Late Devonian suture between Gondwana and Armorica. The kinematics of polyphase deformation in these rocks is reconstructed based on 3D microstructural analysis of inclusion trails within garnet and pseudomorphed lawsonite porphyroblasts using differently oriented thin sections and X-ray tomography. Three sets of inclusion trails striking NE–SW, NNW–SSE, and WNW–ESE are recognized and interpreted to witness a succession of different crustal shortening directions orthogonal to these strikes. The curvature sense of sigmoidal and spiral-shaped inclusion trails of the youngest set is shown to be consistent with northwest and northward subduction of Gondwana under Armorica, provided that these microstructures developed by overgrowth of actively forming crenulations without much porphyroblast rotation. Strongly non-cylindrical folds locally found on the island are reinterpreted as fold-interference structures instead of having formed by progressive shearing and fold-axis reorientation. Six samples of a lower-grade footwall unit of the Groix ophiolitic nappe (Pouldu schists) were also studied. Inclusion trails in these rocks strike E–W, similar to the youngest set recognized on Groix island. They record Carboniferous N–S shortening during continental collision. These new microstructural data from southern Brittany bear a strong resemblance to earlier measured in inclusion-trail orientations in the northwestern Iberia Massif. A best fit between both regions suggests not more than about 15∘ anticlockwise rotation of Iberia during the Cretaceous opening of the Gulf of Biscay.

scholarly journals Provenance of Paleocene–Eocene red beds from NE Iraq: constraints from framework petrography

2014 ◽  
Vol 151 (6) ◽  
pp. 1034-1050 ◽  
Author(s):  
MUATASAM MAHMOOD HASSAN ◽  
BRIAN G. JONES ◽  
SOLOMON BUCKMAN ◽  
ALI ISMAEL AL-JUBORY ◽  
FAHAD MUBARAK AL GAHTANI
Keyword(s):  
Foreland Basin ◽  
Source Area ◽  
Coarse Grained ◽  
Arabian Plate ◽  
Red Beds ◽  
Northern Iraq ◽  
Rock Fragments ◽  
Clastic Rocks ◽  
The North ◽  
Red Bed

AbstractThe red-bed deposits in northern Iraq are situated in an active foreland basin adjacent to the Zagros Orogenic Belt, bound to the north by the Iranian plate thrust over the edge of the Arabian plate. The red-bed successions are composed of alternating red and brown silty mudstones, purplish red calcareous siltstone, fine- to coarse-grained pebbly sandstone and conglomerate. The red beds in the current study can be divided into four parts showing a trend of upward coarsening with fine-grained deposits at the top. A detailed petrographic study was carried out on the sandstone units. The clastic rocks consist mainly of calcite cemented litharenite with rock fragments (volcanic, metamorphic and sedimentary), quartz and minor feldspar. The petrographic components reflect the tectonic system in the source area, laterally ranging from a mixed orogenic and magmatic arc in Mawat–Chwarta area to recycled orogenic material rich in sedimentary rock fragments in the Qandel area. The Cretaceous–Palaeogene foreland basin of northern Iraq formed to the southwest of the Zagros Suture Zone and the Sanandaj–Sirjan Zone of western Iran. During Palaeogene time deposition of the red beds was caused by renewed shortening in the thrust sheets overlying the Arabian margin with uplift of radiolarites (Qulqula Formation), resulting in an influx of radiolarian debris in addition to continuing ophiolitic detritus. Mixed sources, including metamorphic, volcanic and sedimentary terranes, were present during deposition of the upper part of the red beds.

scholarly journals Stratigraphic Analysis of Gercus Formation in Dohuk area, Northern Iraq

2020 ◽  
pp. 2293-2302
Author(s):  
Karrar Hassooni Awad ◽  
Hamid Ali Ahmed Alsultan
Keyword(s):  
Late Eocene ◽  
Sediment Supply ◽  
Arabian Plate ◽  
Eurasian Plate ◽  
Delta Front ◽  
Northern Iraq ◽  
Base Level ◽  
Accommodation Space ◽  
Surface Section ◽  
The Difference

A surface section of the Gercus Formation (Middle-Late Eocene) was studied in Berafat area, Dohuk Governorate, Northern Iraq. The Gercus Formation consists of a mixed siliciclastic sediments, evaporates and carbonate sequences in the studied region, predominantly in the upper and middle parts. Nevertheless, it usually consists of upward-fining carbonate-rich sandstone cyclothems, marl, conglomerate and siltstone along with a gypsum lens and thin micrite carbonate beds.  The Gercus Formation was deposited in delta and delta front of occasionally depositional environment which is represented by red-brown claystone and reddish-brown mudstone lithofacies. Cross bedded  pebbly sandstone, trough cross-bedded sandstone  and laminated cross-bedded sandstone lithofacies are deposited in braided delta  environment. Marl lithofacies and gypsum lithofacies are deposited in intertidal and supratidal environments. The sea level fluctuation caused the river base level to occasionally rise and fall. In addition, the process changed from erosion to deposition, while the grain size also changed at different environments from gravel to sand and clays. The Gercus succession of northern Iraq was developed during the Middle-Late Eocene in an active margin basin, where the last stage closure of the New-Tethys and its collision with the Eurasian plate took place between the northeastern Arabian plate. It caused major episodes of uplifts and subsidence along with base level variations due to eustatic ups and downs. Within Gercus Formation, several fourth order cycles can be recognized, reflecting generally asymmetrical cycles, as well as the difference between sediment supply and accommodation space.

scholarly journals Taking better advantage of fold axis data to characterize anisotropy of complex folded structures in the implicit modeling framework

2021 ◽  
Author(s):  
Laure Pizzella ◽  
Robin Alais ◽  
Simon Lopez ◽  
Xavier Freulon ◽  
Jacques Rivoirard
Keyword(s):  
Field Measurements ◽  
Field Method ◽  
Complex Case ◽  
Fold Axis ◽  
Implicit Methods ◽  
Modeling Framework ◽  
Local Anisotropy ◽  
Use Of Data ◽  
Practical Guidelines ◽  
Folded Structures

Abstract When too few field measurements are available for the geological mod-ling of complex folded structures, results of implicit methods typically exhibit an unsatisfactory bubbly aspect. However, in such cases, anisotropy data are often readily available but not fully exploited. Among them, fold axis data are a straightforward indicator of this local anisotropy direction. Focusing on the so-called potential field method, this work aims to evaluate the effect of the incorporation of such data into the modeling process. Given locally sampled fold axis data, this paper proposes to use the second-order derivatives of the scalar field in addition to the existing first-order ones. The mathematical foundation of the approach is developed and the respective efficiencies of both kinds of constraints are tested. Their integration and impact are discussed based on a complex case study, thereby providing practical guidelines to geomodeling tool users on the parsimonious use of data for the geological modeling of complex folded structures

Palaeomagnetic study of Tertiary volcanic domains in Southern Turkey and Neogene anticlockwise rotation of the Arabian Plate

2009 ◽  
Vol 465 (1-4) ◽  
pp. 114-127 ◽  
Author(s):  
H. Gürsoy ◽  
O. Tatar ◽  
J.D.A. Piper ◽  
A. Heimann ◽  
F. Koçbulut ◽  
...  
Keyword(s):  
Arabian Plate ◽  
Anticlockwise Rotation ◽  
Southern Turkey

scholarly journals BIOSTRATIGRAPHIC CORRELATION OF PALEOZOIC ROCKS IN NORTHERN AND WESTREN IRAQ

2020 ◽  
Vol 8 (3) ◽  
pp. 315-323
Author(s):  
Falah H. Khalaf Al-jubori ◽  
Akram K. Youkhana ◽  
Srood F. Naqshabandi ◽  
Dyana A. Bayz
Keyword(s):  
Regional Distribution ◽  
Source Rocks ◽  
Western Desert ◽  
Upper Permian ◽  
Upper Ordovician ◽  
Northern Iraq ◽  
Clastic Rocks ◽  
Western Desert Of Iraq ◽  
Paleozoic Rocks ◽  
Stratigraphic Succession

The Paleozoic rocks outcropped in northern Iraq (Ora, Chia Zairi section) are biostratigraphically investigated for their microfossils content. Benthonic foraminifera and algal genera characterize the upper part of the section while palynomorphs (Miospores & Acritarchs) dominated the lower part the section which is consist of clastic sediments. The study also include the stratigraphic succession of the section and its correlation to the subsurface sections penetrated in oil and  water wells drilled in the western desert of Iraq in order to determine the regional distribution of the economically important formations, either  as reservoir or as source  rocks for hydrocarbons. Index palynomorphs including many types of Acritarch genera are identified in the Khabour Formation indicate lower Ordovician time (Tremadocian? Arenigian –Llanvirnian: age) The Perispik Formation has been found barren of any type of microfossils and is composed of red clastic rocks. Pollen and Spores are recorded from the "Ore Group"  (Kaista, Ora and Harur Formations )  indicate that these rocks are of Upper Devonian – Lower Carboniferous  (Famennian – Tournaisian age ) .A Large number of  foraminifera and Algal genera are identified in the Chiazairi rocks,these genera and species are indicated the Upper Permian rocks of Thuringian age. The stratigraphic   succession of the Paleozoic section studied in northern Iraq indicate that there is a stratigraphic break represents by missing of the Ga'ara Formation (late Carboniferous –early Permian) and Akkas Formation (Silurian) and the upper part of the Khabour Formation (Upper Ordovician).

scholarly journals Paleostress Analysis of the Northeastern Limb of Pulkhana Anticline /NE Iraq: Implications for Arabian Plate Tectonic Evolution

2020 ◽  
pp. 2925-2952
Author(s):  
Burkan S. Othman ◽  
Zakariya Q. Jadda
Keyword(s):  
Early Stage ◽  
Bedding Plane ◽  
Acute Angle ◽  
Arabian Plate ◽  
Stress Axis ◽  
Fold Axis ◽  
Oblique Collision ◽  
The North ◽  
North Eastern ◽  
Paleostress Analysis

Pulkhana anticline is located in Tuzhurmatu area, about 50 km SE of Kirkuk city. The study area forms a part of the Zagros Folded Zone which is situated in the unstable shelf of Iraq within the physiographic zone called Foothill Zone (in the middle of Hemrin- Makhul subzone). The north eastern limb of the anticline reaches to 50ᵒ and the dip of the  south western limb reaches to 70ᵒ. The core of the structure comprises the rocks of Fat’ha Formation surrounded by rocks of Injana and Mukdadiya Formations, whereas Bai-Hasan Formation forms the slopes of the low hills surrounding the anticline. These Formations range in age from Middle Miocene to Pliocene. More than 761 readings of joint planes were collected from 20 stations within 5 traverses in the study area. The study of joint sets and system was within Injana and Mukhdadiya formations, along traverses with 3-5 stations for each travers track. The results showed the presence of two sets of tension joints (bc, ac) and five sets of shear joints, through defining the maximum stress axis (σ1) and acute angle  dividers for these conjugate joints. It was determined that two directions of Paleostress are present in the area, which are NE-SW and NW-SE. The direction of the first major stress (NE-SW) is orthogonal with, or normal to, the fold axis in the study area, which can be considered as a horizontal component which resulted from oblique collision of Arabian and Eurasian Plates. This old compressive stress is the reason behind the formation of the tension joint (ac) and shear joints, where the sets (ac) and system are perpendicular-semi perpendicular to the bedding plane, as they were formed at an early stage of folding. Also, the ) joint was formed in five tectonic stages with different time intervals. Joints formed in different tectonic stages, in the study area, are attributed to oblique collision of Arabian and Eurasian plates and counter clockwise rotation of Arabian plate relative to Eruasian plate.

Palaeomagnetic study of the Karacadağ Volcanic Complex, SE Turkey: Monitoring Neogene anticlockwise rotation of the Arabian Plate

2013 ◽  
Vol 608 ◽  
pp. 1007-1024 ◽  
Author(s):  
Fikret Koçbulut ◽  
Zafer Akpınar ◽  
Orhan Tatar ◽  
John D.A. Piper ◽  
Andrew. P. Roberts
Keyword(s):  
Arabian Plate ◽  
Volcanic Complex ◽  
Anticlockwise Rotation ◽  
Se Turkey

scholarly journals Calcareous nannofossil zonation and sequence stratigraphy of the Jurassic System, onshore Kuwait

GeoArabia ◽  
2015 ◽  
Vol 20 (4) ◽  
pp. 125-180
Author(s):  
Adi P. Kadar ◽  
Thomas De Keyser ◽  
Nilotpaul Neog ◽  
Khalaf A. Karam
Keyword(s):  
Upper Jurassic ◽  
Optical Microscope ◽  
Arabian Plate ◽  
Calcareous Nannofossil ◽  
Jurassic System ◽  
Sequence Boundaries ◽  
Stratigraphic Nomenclature ◽  
Stratigraphic Succession ◽  
Middle Callovian ◽  
Lower Bathonian

ABSTRACT This paper presents the calcareous nannofossil zonation of the Middle and Upper Jurassic of onshore Kuwait and formalizes current stratigraphic nomenclature. It also interprets the positions of the Jurassic Arabian Plate maximum flooding surfaces (MFS J10 to J110 of Sharland et al., 2001) and sequence boundaries in Kuwait, and correlates them to those in central Saudi Arabia outcrops. This study integrates data from about 400 core samples from 11 wells representing a nearly complete Middle to Upper Jurassic stratigraphic succession. Forty-two nannofossil species were identified using optical microscope techniques. The assemblage contains Tethyan nannofossil markers, which allow application of the Jurassic Tethyan nannofossil biozones. Six zones and five subzones, ranging in age from Middle Aalenian to Kimmeridgian, are established using first and last occurrence events of diagnostic calcareous nannofossil species. A chronostratigraphy of the studied formations is presented, using the revised formal stratigraphic nomenclature. The Marrat Formation is barren of nannofossils. Based on previous studies it is dated as Late Sinemurian–Early Aalenian and contains Middle Toarcian MFS J10. The overlying Dhruma Formation is Middle or Late Aalenian (Zone NJT 8c) or older, to Late Bajocian (Subzone NJT 10a), and contains Lower Bajocian MFS J20. The overlying Sargelu Formation consists of the Late Bajocian (Subzone NJT 10b) Sargelu-Dhruma Transition, and mostly barren Sargelu Limestone in which we place Lower Bathonian MFS J30 near its base. The lower part of the overlying Najmah Formation consists of the Najmah Shale, which is subdivided into three subunits: (1) barren Najmah-Sargelu Transition, (2) Late Bathonian to Middle Callovian (lower Zone NJT 12) Lower Najmah Shale, and (3) Middle Callovian to Middle Oxfordian (upper Zone NJT 12 to NJT 13b) Upper Najmah Shale. Middle Callovian MFS J40 and Middle Oxfordian MFS J50 are positioned near the base and top of the Upper Najmah Shale. The upper part of the Najmah Formation is represented by the Late Oxfordian (Subzone NJT 13b) Najmah Limestone, and is overlain by the Kimmeridgian (Zone NJT 14) Jubaila Formation. Early Kimmeridgian MFS J60 and Late Kimmeridgian MFS J70 are positioned near the base and top of the Jubaila Formation. The positions of Late Jurassic MFS J80, J90 and J100 are not constrained by our biostratigraphic data and are positioned in the Gotnia Formation. The Upper Tithonian MFS J110 and the Jurassic/Cretaceous boundary are positioned in the Makhul Formation.

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