scholarly journals Kinematic evolution and quantification of deformation in external orogenic zones: a case study from the Tunisian Atlas

2016 ◽  
Vol 67 (4) ◽  
pp. 391-401 ◽  
Author(s):  
Mohamed Sadok Bensalem ◽  
Soulef Amamria ◽  
Mohamed Ghanmi ◽  
Fouad Zargouni
Keyword(s):  
Structural Evolution ◽  
Direct Calculation ◽  
Normal Faults ◽  
Tectonic Structures ◽  
Tectonic Inheritance ◽  
Kinematic Evolution ◽  
Extensional Tectonic ◽  
Southern Central ◽  
Tunisian Atlas

Abstract The quantification of deformation is one of the main objectives studied by geologists in order to control the evolution of tectonic structures and their kinematics during different tectonic phases. One of the most reliable methods of this theme is the direct calculation of quantity of deformation based on field data, while respecting several parameters such as the notion of tectonic inheritance and reactivation of pre-existing faults, or the relationship between the elongation and shortening axis with major faults. Thus, such a quantification of deformation in an area may explain the relations of thin- and thick-skinned tectonics during this deformation. The study of structural evolution of the Jebel Elkebar domain in the southern-central Tunisian Atlas permits us to quantify the deformation during the extensional phase by a direct calculation of the vertical throw along normal faults. This approach is verified by calculation of thickness of eroded strata in the uplifted compartment and of resedimented series, named the Kebar Formation, in the downthrown compartment. The obtained results confirm the importance of the Aptian-Albian extensional tectonic regime. The extent of deformation during the compressional phase, related to reactivation of pre-existing faults, is less than that of extensional phases; indeed the compressive reactivation did not compensate the vertical throw of normal faults. The geometry of the Elkebar fold is interpreted in terms of the “fault-related fold” model with a décollement level in the Triassic series. This permitted the partition of deformation between the basement and cover, so that the basement was allowed for a limited transport only, and the maximum of observed deformation was concentrated in the thin-skinned tectonics.

Modeling of the principal parameters controlling the evolution of deformation in Atlassic belts: case study of the southern-central Tunisian Atlas

2017 ◽  
Vol 3 (1) ◽  
Author(s):  
Mohamed Sadok Bensalem ◽  
Mohamed Hedi Bensalem ◽  
Soulef Amamria ◽  
Mohamed Ghanmi ◽  
Fouad Zargouni
Keyword(s):  
Southern Central ◽  
Tunisian Atlas

scholarly journals Progressive tilting of salt-bearing continental margins controls thin-skinned deformation

Geology ◽  
2019 ◽  
Vol 47 (12) ◽  
pp. 1122-1126 ◽  
Author(s):  
Zhiyuan Ge ◽  
Michael Warsitzka ◽  
Matthias Rosenau ◽  
Rob L. Gawthorpe
Keyword(s):  
Coupling Effect ◽  
Structural Evolution ◽  
Normal Faults ◽  
Salt Tectonics ◽  
Continental Margins ◽  
Mechanical Coupling ◽  
High Deformation ◽  
Kinematic Evolution ◽  
Structural Style ◽  
Gravity Driven

Abstract As a primary driving force, margin tilting is crucial for gravity-driven thin-skinned salt tectonics. We investigated how instant versus progressive margin tilting mechanisms influence salt tectonics using an analogue modeling setup where tilting rate could be controlled. Instant tilting resulted in initially high deformation rates, triggering widely distributed upslope extension and downslope contraction. Later, both the extensional and contractional domains migrated upslope as early extensional structures were successively deactivated, while deformation rates decreased exponentially. In contrast, progressive tilting led to downslope migration of the extensional domain by sequentially formed, long-lived normal faults. Contraction localized on a few, long-lived thrusts before migrating upslope. We attribute the distinct structural evolution of thin-skinned deformation, especially in the extensional domain, in the two tilting scenarios mainly to mechanical coupling between the brittle overburden and underlying viscous material. The coupling effect in turn is largely controlled by the deformation rate. By demonstrating the spatiotemporal variations of structural style and kinematic evolution associated with instant versus progressive tilting, we suggest that such variation is identifiable in nature and therefore can provide a new way to analyze margin tilting histories.

scholarly journals Constraining the Passive to Active Margin Tectonics of the Internal Central Apennines: Insights from Biostratigraphy, Structural, and Seismic Analysis

Geosciences ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 160
Author(s):  
Giovanni Luca Cardello ◽  
Giuseppe Vico ◽  
Lorenzo Consorti ◽  
Monia Sabbatino ◽  
Eugenio Carminati ◽  
...  
Keyword(s):  
Seismic Analysis ◽  
Carbonate Platform ◽  
Structural Evolution ◽  
Normal Faults ◽  
Accretionary Wedge ◽  
Central Apennines ◽  
Active Margin ◽  
Kinematic Evolution ◽  
Regional Interest ◽  
Thrust Sheets

The polyphase structural evolution of a sector of the internal Central Apennines, where the significance of pelagic deposits atop neritic carbonate platform and active margin sediments has been long debated, is here documented. The results of a new geological survey in the Volsci Range, supported by new stratigraphic constraints from the syn-orogenic deposits, are integrated with the analysis of 2D seismic reflection lines and available wells in the adjacent Latin Valley. Late Cretaceous syn-sedimentary faults are documented and interpreted as steps linking a carbonate platform to the adjacent pelagic basin, located to the west. During Tortonian time, the pelagic deposits were squeezed off and juxtaposed as mélange units on top of the carbonate platform. Subsurface data highlighted stacked thrust sheets that were first involved into an initial in-sequence propagation with top-to-the-ENE, synchronous to late Tortonian foredeep to wedge-top sedimentation. We distinguish up to four groups of thrust faults that occurred during in-sequence (thrusts 1–3; about 55–60 km shortening) and backthrusting (thrust 4). During Pliocene to recent times, the area has been uplifted and subsequently extended by normal faults cross-cutting the accretionary wedge. Beside regional interest, our findings bear implications on the kinematic evolution of an orogenic wedge affected by far-traveled units.

Depth-dependent inversion of normal faults: Structural analysis of the Penobscot 3D seismic volume, offshore Nova Scotia

2021 ◽  
Author(s):  
Alexander Peace ◽  
Christian Schiffer ◽  
Scott Jess ◽  
Jordan Phethean
Keyword(s):  
Nova Scotia ◽  
Structural Evolution ◽  
Passive Margin ◽  
Normal Faults ◽  
3D Seismic ◽  
Petroleum Systems ◽  
Passive Margins ◽  
Kinematic Evolution ◽  
Kinematic Modelling ◽  
Kinematic Mechanisms

<p>The inversion of rift-related faults on passive margins through kinematic reactivation is documented globally. Such structures form an integral part in petroleum systems, provide essential constraints on the kinematic and structural evolution of rifts and passive margins, and can be used as global markers for far-field stresses. Despite the importance of inverted normal faults, the controls on their kinematic evolution, as well as existence and interactions within fault populations are often poorly constrained. Here, we present new structural interpretation and kinematic modelling of an inverted relay ramp structure located offshore Nova Scotia, Canada. This structure is imaged on the Penobscot 3D seismic reflection survey down to ~3.5 s TWTT, and is constrained by two exploration wells. We map two major normal faults that display evidence for inversion in their lower portions (reverse faulting and low-amplitude folding), below ~2.5 s TWTT, though retain a normal offset in upper sections. The wider fault population is dominated by ~ENE-WSW striking normal faults that dip both north and south, while both of the two major faults dip approximately south and are associated with antithetic and synthetic faults. This kinematic dichotomy along the major faults is important as inversion such as this may go unrecognised if seismic data does not image the full depth of a structure. To accommodate such depth-dependent inversion, if both horizons co-existed during inversion, a reduction in volume of the sedimentary package is required between the normal and reverse segments of the fault. In this study, we explore possible kinematic mechanisms to explain inversion structure and the mechanisms accommodating the volumetric changes/ or mass movements required using fault restoration and strain modelling. Our results favour a poly-phase deformation history that can be reconciled with other inversion structures on related passive-margin segments, suggesting these could be widespread processes.</p>

Tectonic and kinematic evolution within mid-crustal orogenic root zones: a case study from the Caledonides of northwestern Ireland

2001 ◽  
Vol 138 (2) ◽  
pp. 193-211 ◽  
Author(s):  
G. I. ALSOP ◽  
R. BRYSON ◽  
D. H. W. HUTTON
Keyword(s):  
Large Scale ◽  
Root Zone ◽  
Deep Level ◽  
Structural Evolution ◽  
Detailed Examination ◽  
Structural Development ◽  
The South ◽  
The North ◽  
Kinematic Evolution

The Slieve League Peninsula of northwest Ireland lies on the western limb of a major orogenic strike-swing in which regional foliation trends have deviated from the northeast–southwest trends typical of much of Scotland, to west–east orientations. Across-strike coastal exposures on the western tip of the peninsula through Neoproterozoic Dalradian metasediments enable a detailed examination and analysis of the structural evolution of a Caledonian orogenic root zone which has been previously correlated with the Loch Awe Syncline of southwest Scotland. Minor structural development may be evaluated in terms of regional strain profiles and overprinting relationships. Over much of the area, a composite, steep northeast–southwest-trending S2–S3 foliation containing a gently southwest-plunging quartz mineral elongation lineation is the dominant fabric at outcrop, and is associated with MP2 almandine–amphibolite facies metamorphism. F2 folds are isoclinal with curvilinear hinges and similar geometry. They typically plunge steeply towards the southwest and display variable (dextral) or north-directed vergence, whilst minor F3 fold hinges plunge moderately towards the southwest and typically verge (sinistrally) towards the south. Major, composite D1–D3 tectonic slides are developed in the Argyll Group. Structural and stratigraphic relationships indicate that D1 induced large-scale reversals in younging across tectonic slides, resulting in reversals in subsequent F2 and F3 facing patterns. Tectonic sliding is associated with an intensification of strain demonstrated by increasingly intrafolial and curvilinear folding, together with extensional crenulations, sheared quartz pods and metre-scale asymmetric boudinage of metadolerites, all of which indicate dextral (D2) and sinistral (D3) shear. After unfolding subsequent folds (F4), this corresponds to top-to-the-north (D2) and top-to-the-south (D3) translations. D4 results in regionally northwest-verging structures, with minor crenulations and the S4 cleavage transecting fold hinges in an anticlockwise sense, suggesting a dextral component of deformation. The detailed kinematic data indicate that the overall geometry of this western, deep-level arm of the root zone is not a product of the classic mushrooming fountain of nappes model, but rather major interference between consistent northerly directed D2 thrusting and a later phase of southeast-directed (D3) retrocharriage (‘back-folding’) which intensifies towards the south.

Optimizing preventive maintenance over a finite planning horizon in a semi-Markov framework

2020 ◽  
Author(s):  
Antonio Sánchez Herguedas ◽  
Adolfo Crespo Márquez ◽  
Francisco Rodrigo Muñoz
Keyword(s):  
Preventive Maintenance ◽  
Recurrence Relations ◽  
Direct Calculation ◽  
Planning Horizon ◽  
Practical Implementation ◽  
Practical Application ◽  
Mathematical Solution ◽  
Accumulated Reward ◽  
Finite Planning Horizon

Abstract This paper describes the optimization of preventive maintenance (PM) over a finite planning horizon in a semi-Markov framework. In this framework, the asset may be operating, and providing income for the asset owner, or not operating and undergoing PM, or not operating and undergoing corrective maintenance following failure. PM is triggered when the asset has been operating for τ time units. A number m of transitions specifies the finite horizon. This system is described with a set of recurrence relations, and their z-transform is used to determine the value of τ that maximizes the average accumulated reward over the horizon. We study under what conditions a solution can be found, and for those specific cases the solution τ* is calculated. Despite the complexity of the mathematical solution, the result obtained allows the analyst to provide a quick and easy-to-use tool for practical application in many real-world cases. To demonstrate this, the method has been implemented for a case study, and its accuracy and practical implementation were tested using Monte Carlo simulation and direct calculation.

Tectonique synsedimentaire d'age cretace superieur en Tunisie nord orientale; blocs bascules et reorganisation des aires de subsidence

2000 ◽  
Vol 171 (4) ◽  
pp. 431-440 ◽  
Author(s):  
Lahcen Boutib ◽  
Fetheddine Melki ◽  
Fouad Zargouni
Keyword(s):  
Structural Analysis ◽  
Upper Cretaceous ◽  
Tectonic Activity ◽  
Normal Faults ◽  
Half Graben ◽  
Combined Movements ◽  
Basin Floor ◽  
Tunisian Atlas ◽  
Facies Variation ◽  
Regional Tectonics

Abstract Structural analysis of late Cretaceous sequences from the northeastern Tunisian Atlas, led to conclude on an active basin floor instability. Regional tectonics resulted in tilted blocks with a subsidence reorganization, since the Campanian time. These structural movements are controlled both by N140 and N100-120 trending faults. The Turonian-Coniacian and Santonian sequences display lateral thickness and facies variation, due to tectonic activity at that time. During Campanian-Maastrichtian, a reorganization of the main subsidence areas occurred, the early Senonian basins, have been sealed and closed and new half graben basins developed on area which constituted previously palaeohigh structures. These syndepositional deformations are characterized by frequent slumps, synsedimentary tilting materials, sealed normal faults and progressive low angle unconformities. These tilted blocks combined to a subsidence axis migration were induced by a NE-SW trending extensional regime. This extension which affects the Tunisian margin during the Upper Cretaceous, is related to the Tethyan and Mesogean rifting phase which resulted from the combined movements of the African and European plates.

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