scholarly journals Using Chaos and Ant Track Attributes to Recognize The Faulting Systems and Subtle Faults of a Jurassic - Cretaceous Sedimentary Packages in Merjan_West Kifl Oil Fields - Central Iraq

2019 ◽  
pp. 1350-1361
Author(s):  
Mohammed Sadi Fadhil ◽  
Ali M. Al-Rahim
Keyword(s):  
Gravitational Collapse ◽  
Seismic Data ◽  
Lower Cretaceous ◽  
Upper Cretaceous ◽  
Three Dimensional ◽  
Lower Jurassic ◽  
Passive Margin ◽  
Oil Fields ◽  
Normal Faults ◽  
Seismic Sections

Study of three dimensional seismic data of Merjan area-central Iraq has shown that the Jurassic – Cretaceous succession is affected by faulting system. Seven major normal faults were identified and mapped. Synthetic traces have been calculated by using sonic and density log data of the well Me-1.Two exploration wells were drilled in the area Me-1 and Wkf-1 wells, the distance between them is 15.82 km. Discussion about the effect of this system on the sedimentary package has been presented. The tight faults that couldn’t be distinguished it on seismic sections were determined using seismic attributes. They have different strike and limited in their vertical and horizontal extension. They are system facilitates the movement or migration of the fluid across the stratigraphic column in the study area. Faulting framework can be divided into two groups: the first affects the Jurassic and lower Cretaceous rocks and the second effect the upper Cretaceous and lower Tertiary rocks. The first group is associated with the post rift thermal sag, passive margin progradation and gravitational collapse (lower Jurassic – upper Cretaceous (Turonian) 022 – 93 Ma); approximately Sargelue – NahrUmr depositional time. The second group is few and is associated with the rifting creating the Euphrates graben (Late Turonian – Maastrichtian 90 – 70 Ma) approximately Tanuma shale / Sadi – Shiranish) depositional time.

Mid-crustal detachment beneath southern Timor-Leste: seismic evidence for Australian basement in the Timor collision complex (and implications for prospectivity)

2021 ◽  
Author(s):  
T. R. Charlton
Keyword(s):  
Seismic Data ◽  
Passive Margin ◽  
Petroleum Exploration ◽  
Seismic Survey ◽  
Normal Faults ◽  
Thrust Belt ◽  
Collision Complex ◽  
Fold And Thrust Belt ◽  
Timor Leste ◽  
Seismic Sections

Seismic data originally acquired over SW Timor-Leste in 1994 shows two consistent seismic reflectors mappable across the study area. The shallower ‘red’ reflector (0.4-1s twt) deepens southward, although with a block-faulted morphology. The normal faults cutting the red marker tend to merge downward into the deeper ‘blue’ marker horizon (0.5-2.8s twt), which also deepens southward. Drilling intersections in the Matai petroleum exploration wells demonstrate that the red marker horizon corresponds to the top of metamorphic basement (Lolotoi Complex), while the blue marker horizon has the geometry of a mid-crustal extensional detachment. We see no indications for thrusting on the seismic sections below the red marker horizon, consistent with studies of the Lolotoi Complex at outcrop. However, surficial geology over much of the seismic survey area comprises a thin-skinned fold and thrust belt, established in 8 wells to overlie the Lolotoi Complex. We interpret the fold and thrust belt as the primary expression of Neogene arc-continent collisional orogeny, while the Lolotoi Complex represents Australian continental basement underthrust beneath the collision complex. In the seismic data the basal décollement to the thrust belt dips southward beneath the synorogenic Suai Basin on the south coast of Timor, and presumably continues southward beneath the offshore fold and thrust belt, linking into the northward-dipping décollement that emerges at the Timor Trough deformation front. The same seismic dataset has been interpreted by Bucknill et al. (2019) in terms of emplacement of an Asian allochthon on top of an imbricated Australian passive margin succession. These authors further interpreted a subthrust anticlinal exploration prospect beneath the allochthon, which Timor Resources plan to drill in 2021. This well (Lafaek) will have enormous significance not only commercially, but potentially also in resolving the long-standing allochthon controversy in Timor: i.e., does the Lolotoi Complex represent ‘Australian’ or ‘Asian’ basement?

Empirical observations relating near‐surface magnetic anomalies to high‐frequency seismic data and Landsat data in eastern Sheridan County, Montana

Geophysics ◽  
1991 ◽  
Vol 56 (10) ◽  
pp. 1553-1570 ◽  
Author(s):  
John A. Andrew ◽  
Duncan M. Edwards ◽  
Robert J. Graf ◽  
Richard J. Wold
Keyword(s):  
Seismic Data ◽  
Magnetic Anomalies ◽  
Oil Fields ◽  
Data Types ◽  
Seismic Line ◽  
Near Surface ◽  
The North ◽  
Basement Faults ◽  
Magnetic Basement ◽  
Seismic Sections

Our empirical synergistic correlations of aeromagnetic and seismic data and a Landsat lineament interpretation revealed lineations on the magnetic map that have expression on seismic sections. We observed a conjugate set of northwest‐southeast and northeast‐southwest trending magnetic lineaments (zones which offset and truncate near‐surface magnetic anomalies). We believe these OZs (offset zones) represent lateral faults in a wrench‐fault system. Lateral offsets appear to be 100s of meters to a few kilometers (fractions of a mile to a few miles). We observed a direct correlation between OZs and vertical faults in seismic data. Faults on seismic sections extend from near the surface to near the seismic basement. The faults are most pronounced in the Upper Cretaceous reflectors and seem to disappear with depth. Fault throws are inconsistent (reversing throw across faults). OZs trend northeast‐southwest in the north half of the study area and both northeast‐southwest and northwest‐southeast in the south half. The OZ direction of northeast‐southwest in the north half of the survey is confirmed with seismic data. The northwest‐southeast seismic line contains numerous faults and the northeast‐southwest seismic line contains few faults. Most northeast‐southwest faults do not appear to reach seismic basement and are not seen in an interpretation of the magnetic basement. In two cases, northwest‐southeast OZs and correlative Landsat lineaments coincide with mapped magnetic basement faults. These magnetic basement faults can be seen in seismic data too. Faults trending northwest‐southeast may represent Precambrian faults reactivated during the Laramide Orogeny. Movement along these faults possibly generated the northeast‐southwest faults. Most oil fields have an associated near‐surface magnetic anomaly. Other near‐surface magnetic anomalies occur over obvious, untested (in 1985), seismic character or amplitude anomalies in seismic events which correlate with producing intervals in the oil fields. This synergistic correlation is the most important single observation from our study. Different data types and interpretation techniques identified the same geologic trends and prospective geographical areas. This fundamentally important information is often lost in bickering over which filter or processing technique to use or in arguments over which data type is “more important” than others. Further, if the synergistic correlation of data types were not done, the importance of the anomalous features in each individual data type may not have been recognized.

scholarly journals A Model for the evolution of the Weald

2002 ◽  
Vol 49 ◽  
pp. 109-118
Author(s):  
David Lundbek Hansen ◽  
Søren Bom Nielsen ◽  
Derek J. Blundell
Keyword(s):  
Lower Cretaceous ◽  
Mechanical Model ◽  
Normal Faults ◽  
Crustal Extension ◽  
The South ◽  
Physical Explanation ◽  
Extensional Basin ◽  
The North ◽  
Sequence Of Events ◽  
Seismic Sections

The Weald Basin developed through the Jurassic–Lower Cretaceous as an extensional basin founded upon E–W trending low-angle faults that were probably Variscan thrusts, subsequently reactivated as normal faults. Later, the basin was inverted and uplifted into a broad dome, whilst the London Basin to the north, and the Hampshire–Dieppe Basin to the south, subsided as flanking basins during the late Palaeocene–Eocene. Seismic sections across the Weald indicate that inversion resulted from north-directed stress. A stratigraphic reconstruction based on a N–S profile across the Weald and flanking basins serves as a template for a forward, 2D thermo-mechanical model that simulates the evolution of the Weald Basin through crustal extension and its inversion, and subsidence of the flanking basins, through compression. The model provides a physical explanation for this sequence of events, requiring a region of crust of reduced strength relative to its flanks. This weak region is the location of crustal-scale Variscan thrusts that have been reactivated subsequently. The strong crust on the flanks is essential for the development of flanking basins during inversion and uplift of the Weald.

STRUCTURE AND DEVELOPMENT OF THE SOUTHERN MARGIN OF AUSTRALIA

1975 ◽  
Vol 15 (1) ◽  
pp. 33 ◽  
Author(s):  
M. G. Boeuf ◽  
H. Doust
Keyword(s):  
Continental Margin ◽  
Seismic Data ◽  
Lower Cretaceous ◽  
Rift Valley ◽  
Upper Cretaceous ◽  
Structural Data ◽  
Theoretical Models ◽  
Palaeomagnetic Data ◽  
Geological Evolution ◽  
Seismic Records

Off the southern coast of Australia, exploration results and deep-water reconnaissance seismic data support the concept of an aseismic Atlantic-type continental margin. Characteristic is a sedimentary wedge which extends from the shelf to the abyssal plains and includes crustal elements of continental and oceanic origin.Oceanward, a continuous level of diffractions ascribed to the top of oceanic crust can be observed on seismic records, steeply dipping beneath the continental rise towards a smooth, flat, often faulted reflector which is correlated with top Precambrian or Palaeozoic continental basement.The sedimentary wedge which overlies the block-faulted and collapsed continental basement is subdivided by unconformities into: (a) a continental Lower Cretaceous unit and a fluviodeltaic unit of Upper Cretaceous-Danian age which are taken to represent rift valley stages of deposition controlled by extensional tectonics and (b) a post-breakup sequence of Tertiary units representing regional collapse and out-building of the shelf. The Upper Cretaceous sequence is missing along much of the continental edge where Tertiary sediments appear to rest directly on the Lower Cretaceous unit.Our interpretation suggests that a prolonged period of uplift took place along the axis of the rift valley prior to continental break-up. On the basis of palaeomagnetic data and biostratigraphic analysis the breakup phase started in the Upper Paleocene.From the continent outward several structural zones can commonly be recognised: (a) a zone of shallow basement with a thin Lower Cretaceous cover normally faulted and overlain by thin gently dipping Tertiary beds, (b) a zone of faulted and landwards tilted basement blocks and Lower Cretaceous sediments overlain (sometimes with clear unconformity) by thick Upper Cretaceous sediments, (c) a zone of thick, moderately deformed Tertiary sediments whose axis of deposition is generally offset to the south of the Upper Cretaceous basinal axis, (d) a zone of rotational faults and associated toe thrusts affecting the Cretaceous sediments and apparently related to the time of margin collapse, (e) an area of little disturbed Cretaceous and Tertiary sediments overlying continental basement. This zone extends into the "magnetic quiet zone" which is therefore believed to be, at least in part, a collapsed portion of the continental margin adjacent to oceanic crust.The interpretation of the geological evolution of the southern Australian margin based on the stratigraphic and structural data presently available can be related to current theoretical models on continental margin development.

Transect across the External Pamir thrust belt and Main Pamir Thrust along the Altyn Darya valley, Kyrgyzstan

2021 ◽  
Author(s):  
Jonas Kley ◽  
Thomas Voigt ◽  
Edward R. Sobel ◽  
Johannes Rembe ◽  
Chen Jie
Keyword(s):  
Cross Section ◽  
Lower Cretaceous ◽  
Upper Cretaceous ◽  
Hanging Wall ◽  
Lower Jurassic ◽  
Late Triassic ◽  
Thrust Belt ◽  
The South ◽  
Late Neogene ◽  
Basal Detachment

<p>The ca. 35 km long, N-S-trending Altyn Darya valley in Kyrgyzstan exposes a nearly complete cross-section of the External Pamir thrust belt (EP), extending from the active Pamir Frontal Thrust in the north to the Main Pamir Thrust (MPT) and some distance into its hanging-wall. The EP comprises a northward imbricated stack of Carboniferous to Late Neogene rocks. From north to south, young clastics of the Alai Valley foreland basin are overthrust by an intensely folded and thrust-repeated frontal stack of Upper Cretaceous to Paleogene limestone, shale and evaporite. Lower Cretaceous red sandstones first emerge above north- and south-verging thrusts forming a triangle zone whose core comprises spectacular isoclinal folds in Upper Cretaceous strata. Towards the south, another thrust imbricate of Lower Cretaceous is overthrust by Late Triassic-Jurassic sandstones and mafic volcanics which are themselves overthrust by an internally deformed, Carboniferous to Triassic succession of, from bottom to top, greywacke and shale, limestone, volcanoclastic conglomerates, variegated sandstone-shale and pink conglomerates. The Carboniferous units in the south are truncated by the MPT which emplaces a succession of greenschist, marble and chert overlain by a km-thick sequence of metamorphosed and deformed, pillow-bearing lavas of Carboniferous age. Structural geometries and fault preference indicate that the basal detachment of the EP deepens southward very gently, stepping down from a detachment in Upper Cretaceous shale to another one near the base of the Lower Cretaceous and eventually a third one in Triassic shale. Cross-section balancing suggests minimum shortening of 75 km for units in the MPT´s footwall. The displacement on the MPT is poorly constrained due to eroded hanging-wall cutoffs, but must exceed 15 km. The basal detachment cuts into basement no earlier than 100 km from the present thrust front, too far south to link up with the top of the Pamir slab.</p><p>The stratigraphic succession exposed in Altyn Darya can be readily correlated with less deformed and less metamorphosed transects in westernmost China (Qimgan and Kawuke), some 250 km to the east. A marble-greenschist sequence similar to that carried on the MPT in Altyn Darya has been identified there as a tectonic nappe of the Karakul-Mazar unit, emplaced from the south already in an Upper Triassic to Lower Jurassic (Late Cimmerian) event. If the correlation is correct, then the MPT had a Mesozoic precursor structure extending over much of the E-W striking segment of the Northern Pamir.</p>

Geophysical constraints and model of the “Saxothuringian and Rhenohercynian subductions – magmatic arc system” in NE France and SW Germany

2009 ◽  
Vol 180 (6) ◽  
pp. 545-558 ◽  
Author(s):  
Jean-Bernard Edel ◽  
Karel Schulmann
Keyword(s):  
Subduction Zone ◽  
Early Carboniferous ◽  
Passive Margin ◽  
Normal Faults ◽  
Time Range ◽  
Early Paleozoic ◽  
Rhenish Massif ◽  
Magmatic Arc ◽  
Seismic Sections ◽  
Subduction System

Abstract Correlation of geophysical and geological data with the western margin of the Bohemian massif, re-interpretation of the ECORS-DEKORP deep seismic sections, transformations and 3 D modelling of gravimetric and magnetic maps allow to define sequentional Saxothuringian and Rhenohercynian Paleozoic subduction systems in NE France and SW Germany where only 10% of the Early Paleozoic basement is outcropping. Two 35 km spaced and NE-SW trending gravity highs associated with SE dipping reflectors are interpreted as the western continuation of the Teplá Devonian paleo-subduction zone of the Saxothuringian ocean and Early Carboniferous underthrusting of the Saxothuringian passive margin, thereby defining the Saxothuringian subduction system in west Europe. South-eastwards dipping reflectors beneath the Moho are interpreted as witnesses of the Early Carboniferous subduction of the Rhenohercynian ocean. The suture is marked by the gravity high in the phyllite zone of the southern Rhenish Massif. Gravity lows in the SE of gravity highs and weak ondulating reflectors are interpreted in terms of crystalline bulges in the hangingwalls of sutures. The numerous highly magnetic anomalies correspond to magmatic bodies emplaced in the time-range 335–330 Ma, along NW dipping and sinistral normal faults. Located in the hangingwall of the Rhenohercynian subduction zone, this wide magmatic arc trends obliquely with respect to the Saxothuringian subduction system, which is almost obliterated by the wide front of magmatic bodies.

scholarly journals The ophiolite-related Mersin Melange, southern Turkey: its role in the tectonic–sedimentary setting of Tethys in the Eastern Mediterranean region

2004 ◽  
Vol 141 (3) ◽  
pp. 257-286 ◽  
Author(s):  
OSMAN PARLAK ◽  
ALASTAIR ROBERTSON
Keyword(s):  
Lower Cretaceous ◽  
Upper Cretaceous ◽  
Carbonate Platform ◽  
Eastern Mediterranean ◽  
Eastern Mediterranean Region ◽  
Leading Edge ◽  
Vertical Axis ◽  
Upper Jurassic ◽  
Passive Margin ◽  
Southern Turkey

The Mersin Melange underlies the intact Mersin Ophiolite and its metamorphic sole to the south of the Mesozoic Tauride Carbonate Platform in southern Turkey. The Melange varies from chaotic melange to broken formation, in which some stratigraphic continuity can be recognized. Based on study of the broken formation, four lithological associations are recognized: (1) shallow-water platform association, dominated by Upper Palaeozoic–Lower Cretaceous neritic carbonates; (2) rift-related volcanogenic–terrigenous–pelagic association, mainly Upper Triassic andesitic–acidic volcanogenic rocks, siliciclastic gravity flows, basinal carbonates and radiolarites; (3) within-plate-type basalt–radiolarite–pelagic limestone association, interpreted as Upper Jurassic–Lower Cretaceous seamounts with associated radiolarian sediments and Upper Cretaceous pelagic carbonates; (4) ophiolite-derived association, including fragments of the Upper Cretaceous Mersin Ophiolite and its metamorphic sole. Locally, the ophiolitic melange includes granite that yielded a K/Ar radiometric age of 375.7±10.5 Ma (Late Devonian). This granite appears to be subduction influenced based on ‘immobile’ element composition.The Mersin Melange documents the following history: (1) Triassic rifting of the Tauride continent; (2) Jurassic–Cretaceous passive margin subsidence; (3) oceanic seamount genesis; (4) Cretaceous supra-subduction zone ophiolite genesis; (5) Late Cretaceous intra-oceanic convergence-metamorphic sole formation, and (6) latest Cretaceous emplacement onto the Tauride microcontinent and related backthrusting.Regional comparisons show that the restored Mersin Melange is similar to the Beyşehir–Hoyran Nappes further northwest and a northerly origin best fits the regional geological picture. These remnants of a North-Neotethys (Inner Tauride Ocean) were formed and emplaced to the north of the Tauride Carbonate Platform. They are dissimilar to melanges and related units in northern Syria, western Cyprus and southwestern Turkey, which are interpreted as remnants of a South-Neotethys. Early high-temperature ductile transport lineations within amphibolites of the metamorphic sole of the Mersin ophiolite are generally orientated E–W, possibly resulting from vertical-axis rotation of the ophiolite while still in an oceanic setting. By contrast, the commonly northward-facing later stage brittle structures are explained by backthrusting of the ophiolite and melange related to exhumation of the partially subducted northern leading edge of the Tauride continent.

Contribution a l'etude geologique de la chaine calcaire des monts Peloritains (zone de Militello-Tortorici), Sicile nord-orientale

1961 ◽  
Vol S7-III (6) ◽  
pp. 568-579 ◽  
Author(s):  
G. Duee
Keyword(s):  
Lower Cretaceous ◽  
Upper Cretaceous ◽  
Upper Jurassic ◽  
Lower Jurassic ◽  
Tectonic Deformation ◽  
Dolomitic Limestone ◽  
Early Tertiary ◽  
Lower Unit ◽  
Jurassic Limestone ◽  
Northeastern Sicily

Abstract The limestone chain of the Peloritani mountains in northeastern Sicily is made up of several tectonic units differing stratigraphically, and complexly thrust-faulted into various anomalous positions. The Longi (or lower) unit and its eastern extension, the dolomitic unit, comprise 250-300 m of red quartz conglomerate of pre-Liassic age; 500 m of Jurassic limestone and dolomite concordant on the conglomerate; and about 300 m of upper Jurassic-Cretaceous-Eocene marl and limestone. In the Longi unit, a thick molasse of early Tertiary age also occurs. The Galati unit consists of phyllite overlain unconformably by various facies of Mesozoic limestone, dolomitic limestone, marl, and conglomerate. The red limestone unit comprises upper Cretaceous marl overlain by lower Jurassic limestones, Eocene beds transgressive over both, and Oligocene-Miocene molasse at the top. The tectonic relationships of these units are highly complicated. Much thrusting probably occurred prior to deposition of the molasse. Jurassic-lower Cretaceous flysch on the south has been overridden by the chain, but the age of this thrusting is problematic. The molasse seems to have been deposited transgressively over all other formations and tectonic units, but some important tectonic deformation certainly is post-molasse and part is Quaternary.

Multiphase oblique extension on the North West Shelf of Australia

2021 ◽  
Author(s):  
Chris Elders ◽  
Sara Moron
Keyword(s):  
Seismic Data ◽  
Lower Cretaceous ◽  
Passive Margin ◽  
Rift System ◽  
Active Deformation ◽  
North West ◽  
North East ◽  
The North ◽  
Northern Carnarvon Basin ◽  
Carnarvon Basin

<p>The North West Shelf of Australia has experienced numerous rift events during its prolonged evolution that most likely started in the Lower Palaeozoic and continued through to the formation of the present day passive margin in the Lower Cretaceous.  Carboniferous and Permian is associated with rifting of the Lhasa terrane, a phase extension in the Lower and Middle Jurassic associated with the separation of the Argo terrane Upper Jurassic to Lower Cretaceous extension culminated in the separation of Greater India and Australia.  Investigations based on interpretation of extensive, public domain seismic data, combined with numerical mechanical modelling, demonstrate that crustal structure, rheology and structural fabrics inherited from older events exert a significant control on the architecture of younger rifts.</p><p>Defining the older, more deeply buried rift episodes is challenging, but with seismic data that now images deeper structures more effectively, it is clear that NE-SW oriented Carboniferous to Permian aged rift structures control the overall geometry of the margin.  Variations in the timing, distribution and intensity of that rift may account for some of the complexity that governs the Triassic – a failed arm of the rift system might account for the accumulation of thick sequences of fluvio-delatic sediments in an apparent post-rift setting, while active deformation and igneous activity continued elsewhere on the margin.</p><p>A renewed phase of extension began in the latest Triassic in the western part of the Northern Carnarvon Basin, but became progressively younger to the NE.  High-resolution mechanical numerical experiments show that the dual mode of extension that characterises the Northern Carnarvon Basin, where both distributed and localised deformation occurs at the same time, is best explained by necking and boudinage of strong lower crust, inherited form the Permian rift event, proximal to the continental margin, and a subdued extensional strain rate across the distal extended margin.  A very clear and consistent pattern of ENE oriented extension, which interacts obliquely with the older NE-SW oriented Permian aged structures, is apparent across the whole of the Northern Carnarvon Basin and extends north east into the Roebuck and Browse Basins.  This is at odds with the NW-SE oriented extension predicted by the separation of the Argo terrane which occurs at this time.  This may be explained by the detached style of deformation that characterises the Mesozoic interval.  Alternatively, the separation of Greater India may have exerted a stronger influence on the evolution of the margin during the Jurassic than hitherto recognised.</p>

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