scholarly journals Structural Analysis of Northwest Sabah Basin by 2D Reconstruction of Seismic Sections

2018 ◽  
Vol 3 (2) ◽  
pp. 69
Author(s):  
Mohd Akhmal Bin Muhamad Sidek ◽  
Umar Hamzah
Keyword(s):  
Cross Sections ◽  
Geological Structure ◽  
Tectonic Deformation ◽  
Thrust Faults ◽  
Fold Belt ◽  
Thrust Sheet ◽  
Sulu Sea ◽  
The North ◽  
Deformation Processes ◽  
Seismic Sections

The tectonic evolution of thrust fold belt and thrust sheet zone in Northwest Sabah basin was described based on balanced reconstruction of seismic sections representing Mid-Miocene to Recent deposits. The study area is located at the center of a wide crustal deformational zone bordered by the Sunda Shelf on the northeast, Sulu Sea in the southwest and the South China Sea in the northwest. Balancing cross section can be applied after the deformed geological structure geometry is accurately determined from seismic sections and 7 seismic stratigraphic unit from 15 Ma until Recent is consecutively restored. There are four steps involved in retro-deformation processes beginning with removing all faults displacements followed by unfolding the folds, isostasy correction and finally the removal of each compacted layer parts or decomposition. Wider fold wavelengths with least thrust faults were observed from south to north in the seismic sections ranging from 12 to 4 km with an average of about 7 km, while smaller fold wavelengths and more thrust faults were observed in the north based on the same seismic sections. In general, the reconstructed cross sections revealed compressional tectonic deformation activity as shown by shortening strain trending NW-SE. Measurement of total shortening shows that thrust fold belt is imbalance by an exceeds of 14.7 km and more active compared to thrust sheet zone which has only 0.9 km. Results of the study also indicate facies destruction due to shortening which is decreasing towards Pliocene or younger deposits.

A Discussion on natural strain and geological structure - The energy balance and deformation mechanisms of thrust sheets

1976 ◽  
Vol 283 (1312) ◽  
pp. 289-312 ◽  
Keyword(s):  
Total Energy ◽  
Cross Sections ◽  
Thermodynamic System ◽  
Geological Structure ◽  
The Body ◽  
Pressure Solution ◽  
Diagnostic Features ◽  
Thrust Sheet ◽  
Frictional Sliding ◽  
Discrete Surfaces

The total energy involved in emplacing a thrust sheet is expended in initiation and growth of the thrust surface, slip along this surface, and deformation within the main mass of the sheet. This total energy can be determined from potential energy considerations knowing the initial and final geometry from balanced cross sections after defining the thrust’s thermodynamic system boundaries. Emplacement of the McConnell thrust in the Canadian Rockies involved ca. 1019 J of gravitational work, an order of magnitude greater than any possible work by longitudinal compressive surface forces. A new theory for the initiation and growth of thrusts as ductile fractures is based on a demonstration that thrust displacement is linearly related to thrust map length and that fold complexes at the ends of thrusts are constant in size for a given metamorphic grade. Much of the total work is dissipated within the body of the sheet. Field observations show which mechanisms of dissipation are most important at various positions within the thrust sheet, and it is found that only the top 5 km of the McConnell was dominated by frictional sliding. A novel type of sliding along discrete surfaces is pressure solution slip, in which obstacles are by-passed by diffusive mass transfer. Fibres and pressure solution grooves are diagnostic features of this sliding law, in which slip velocity is linearly related to shear stress. Pressure solution slip is widespread at depths greater than about 5 km, but at this depth penetrative whole rock deformation by pressure solution becomes dominant - marked by cleavage and stretching directions - and accounts for much of the finite strain within the thrust sheet. The McConnell thrust has an outer layer which deformed by frictional sliding and this overlies a massive linearly viscous core responsible for much of the energy dissipation and gross mechanical behaviour.

scholarly journals Thrust-fault architecture of glaciotectonic complexes in Denmark

1969 ◽  
pp. 17-20
Author(s):  
Stig A. Schack Pedersen ◽  
Lars Ole Boldreel
Keyword(s):  
Sea Level ◽  
Cross Sections ◽  
Thrust Fault ◽  
Basal Part ◽  
The North ◽  
The North Sea ◽  
Fault Deformation ◽  
Seismic Sections ◽  
Structural Levels ◽  
Fault Architecture

Cross sections of glaciotectonic complexes are exposed in coastal cliff s in Denmark, which allow structural studies of the architecture of thin-skinned thrust-fault deformation (Pedersen 2014). However, the basal part of the thrust-fault complex is never exposed, because it is located 50 to 100 m below sea level. It is in the basal part the most important structure – the décollement zone – of the complex is found. Th e décollement zone constitutes the more or less horizontal surface that separates undeformed bedrock from the displaced thrust-sheet units along the décollement level. One of the most famous exposures of glaciotectonic deformations in Denmark is the Møns Klint Glaciotectonic Complex. Th e structures above sea level are well documented, whereas the structures below sea level down to the décollement level are poorly known. Modelling of deep structures was carried out by Pedersen (2000) but still needs documentation. A glaciotectonic c omplex aff ecting comparable rock units, such as the chalk at Møns Klint, was recently recognised in seismic sections from Jammerbugten in the North Sea (Fig. 1). Th ese sections provide an excellent opportunity for comparable studies of the upper and lower structural levels in thin-skinned thrust-fault deformation, which is discussed in this paper with examples from three major glaciotectonic complexes.

A Discussion on natural strain and geological structure - Strain patterns in the Pyrenean Chain

1976 ◽  
Vol 283 (1312) ◽  
pp. 271-280 ◽  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Horizontal Displacement ◽  
Geological Structure ◽  
Deformation Analysis ◽  
Brittle Deformation ◽  
Deformation Axis ◽  
Narrow Zone ◽  
The North ◽  
East West

The Pyrenean Chain is a deformed part of the crust, fan-shaped in cross section, in which we can define the main characteristics of the major deformation as follows: (a) East—west folds always have their axial planes nearly vertical; the B axes of these folds have gentle plunges; (b) in the domain where schistosity is present (dominent flattening), the direction of maximum apparent elongation on cleavage planes, i.e. the X deformation axis, is nearly parallel to the geometric A axis of the folds. Inside the domain of strong flattening, a very narrow zone is present (less than 2 km wide on some cross sections) bounded by discontinuities, one of the most important is the North Pyrenean fault. This narrow zone is fundamentally different from the rest of the chain: (i) here, the deformation has the highest intensity and the rocks are metamorphosed; (ii) the B axes of the folds are curved and display steep plunges; (iii) the X deformation axis is parallel to the B geometric axis. We imagine that these anomalies have been created by sinistral horizontal displacement on the North Pyrenean fault during the folding. In addition to these facts, a brittle-deformation analysis permits the drawing of deformation trajectories in the flat northern foreland up to 400 km from the chain itself.

Subglacial topography and thickness of ice caps on the Argentine Islands

2019 ◽  
Vol 31 (6) ◽  
pp. 332-344 ◽  
Author(s):  
Jānis Karušs ◽  
Kristaps Lamsters ◽  
Anatolii Chernov ◽  
Māris Krievāns ◽  
Jurijs Ješkins
Keyword(s):  
Land Surface ◽  
Geological Structure ◽  
Aerial Images ◽  
Ice Thickness ◽  
Ice Caps ◽  
The North ◽  
Prevailing Wind Direction ◽  
Aerial Vehicle ◽  
Subglacial Topography ◽  
Ground Penetrating

AbstractThis study presents the first subglacial topography and ice thickness models of the largest ice caps of the Argentine Islands, Wilhelm Archipelago, West Antarctica. During this study, ground-penetrating radar was used to map the thickness and inner structure of the ice caps. Digital surface models of all studied islands were created from aerial images obtained with a small-sized unmanned aerial vehicle and used for the construction of subglacial topography models. Ice caps of the Argentine Islands cover ~50% of the land surface of the islands on average. The maximum thickness of only two islands (Galindez and Skua) exceeds 30 m, while the average thickness of all islands is only ~5 m. The maximum ice thickness reaches 35.3 m on Galindez Island. The ice thickness and glacier distribution are mainly governed by prevailing wind direction from the north. This has created the prominent narrow ice ridges on Uruguay and Irizar islands, which are not supported by topographic obstacles, as well as the elongated shape of other ice caps. The subglacial topography of the ice caps is undulated and mainly dependent on the geological structure and composition of magmatic rocks.

Timing of magmatism, foreland basin development, metamorphism and inversion in the Anglo-Brabant fold belt

1997 ◽  
Vol 134 (5) ◽  
pp. 607-616 ◽  
Author(s):  
G. VAN GROOTEL ◽  
J. VERNIERS ◽  
B. GEERKENS ◽  
D. LADURON ◽  
M. VERHAEREN ◽  
...  
Keyword(s):  
Subduction Zones ◽  
Foreland Basin ◽  
Fold Belt ◽  
East Anglia ◽  
Basin Inversion ◽  
Tectonic Model ◽  
The North ◽  
Basin Development ◽  
The North Sea ◽  
And Inversion

New data implying crustal activation of Eastern Avalonia along the Anglo-Brabant fold belt are presented. Late Ordovician subduction-related magmatism in East Anglia and the Brabant Massif, coupled with accelerated subsidence in the Anglia Basin and in the Brabant Massif during Silurian time, indicate a foreland basin development. Final collision resulted in folding, cleavage development and thrusting during the mid-Lochkovian to mid-Eifelian. In the southeast of the Anglo-Brabant fold belt, Acadian deformation produced basin inversion and the regional antiformal structure of the Brabant Massif. The uplift, inferred from the sedimentology, petrography and reworked palynomorphs in the Lower Devonian of the Dinant Synclinorium is confirmed by illite crystallinity studies. The tectonic model discussed implies the presence of two subduction zones in the eastern part of Eastern Avalonia, one along the Anglo-Brabant fold belt and another under the North Sea in the prolongation of the North German–Polish Caledonides.

Reconstruction of the Reservoir Fine Structure by Using Scattering Attributes

2021 ◽  
Author(s):  
Vladimir Cheverda ◽  
Vadim Lisitsa ◽  
Maksim Protasov ◽  
Galina Reshetova ◽  
Andrey Ledyaev ◽  
...  
Keyword(s):  
Seismic Data ◽  
Numerical Experiments ◽  
Seismic Waves ◽  
Fractured Reservoirs ◽  
Three Dimensional ◽  
Geological Structure ◽  
Discrete Elements ◽  
Digital Twin ◽  
The North ◽  
Slip Surfaces

Abstract To develop the optimal strategy for developing a hydrocarbon field, one should know in fine detail its geological structure. More and more attention has been paid to cavernous-fractured reservoirs within the carbonate environment in the last decades. This article presents a technology for three-dimensional computing images of such reservoirs using scattered seismic waves. To verify it, we built a particular synthetic model, a digital twin of one of the licensed objects in the north of Eastern Siberia. One distinctive feature of this digital twin is the representation of faults not as some ideal slip surfaces but as three-dimensional geological bodies filled with tectonic breccias. To simulate such breccias and the geometry of these bodies, we performed a series of numerical experiments based on the discrete elements technique. The purpose of these experiments is the simulation of the geomechanical processes of fault formation. For the digital twin constructed, we performed full-scale 3D seismic modeling, which made it possible to conduct fully controlled numerical experiments on the construction of wave images and, on this basis, to propose an optimal seismic data processing graph.

scholarly journals Evaluation of the Moisture Sources in two Extreme Landfalling Atmospheric River Events using an Eulerian WRF-Tracers tool

2017 ◽  
Author(s):  
Jorge Eiras-Barca ◽  
Francina Dominguez ◽  
Huancui Hu ◽  
A. Daniel Garaboa-Paz ◽  
Gonzalo Miguez-Macho
Keyword(s):  
Cross Sections ◽  
North Atlantic ◽  
Cold Front ◽  
Wrf Model ◽  
Atmospheric River ◽  
The North ◽  
Northern Latitudes ◽  
The Pacific ◽  
Low Level Jet ◽  
Tropical Moisture

Abstract. A new 3D Tracer tool is coupled to the WRF model to analyze the origin of the moisture in two extreme Atmospheric River (AR) events: the so-called Great Coast Gale of 2007 in the Pacific Basin, and the Great Storm of 1987 in the North Atlantic. Results show that between 80 % and 90 % of the moisture advected by the ARs, as well as between 70 % and 80 % of the associated precipitation have a tropical or subtropical origin. Local convergence transport is responsible for the remaining moisture and precipitation. The ratio of tropical moisture to total moisture is maximized as the cold front arrives to land. Vertical cross sections of the moisture suggest that the maximum in humidity does not necessarily coincide with the Low-Level Jet (LLJ) of the extratropical cyclone. Instead, the amount of tropical humidity is maximized in the lowest atmospheric level in southern latitudes, and can be located above, below or ahead the LLJ in northern latitudes in both analyzed cases.

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