Control of obliquity directions on structural development, from rifting to inversion: Examples from the Tethyan domain

Oblique rift systems form when the axis of rifting is not orthogonal to the direction of tectonic extension, normally due to pre-existing zones of weakness that influence the location and orientation of new faults. Irrespective of the regional-scale obliquity, most individual extensional faults will tend to nucleate according to the orientation of the tectonic stress orientations, and therefore normal to the direction of maximum extension. Transfer faults in oblique systems will tend to form parallel to the direction of extension and, in contrast to orthogonal rifting, will play a major role in the architecture and development of the rift and its sedimentary basins.An intriguing feature in oblique rift systems is the formation of reverse structures evocative of wrench tectonics during the syn-rifting stage. This stems from the orientation of geological structures relative to the direction of tectonic extension. Even slight changes in tectonic transport direction or stress orientations during the development of the rift system can lead to events of transpression or transtension along transfer structures. Because of the relevance of transfer structures in oblique systems, transpression can result in the appearance of discontinuities in the sedimentary record that are often interpreted as, somewhat incongruent, inversion events.Oblique structures also play a crucial role during the full inversion of the rift system during convergence, particularly so because tectonic shortening will strike at an angle to the orientation of faults. Irrespective of the evolution of oblique rifting and inversion, the initial fault pattern is also normally preserved in fully inverted systems involved in fold-and-thrust systems. In many of cases, when the original rift obliquity is not well understood, the characteristic rhomboidal pattern is interpreted to relate to wrench tectonics. &#160;In this presentation we will review evidence from Iberia, Northwestern Africa and the Eastern Alps to discuss the role that obliquity plays in rift development and its inheritance in fold-and-thrust belts with different degrees of inversion.

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Defining structural permeability in Australian sedimentary basins

The APPEA Journal ◽

10.1071/aj14010 ◽

2015 ◽

Vol 55 (1) ◽

pp. 119 ◽

Cited By ~ 2

Author(s):

Adam Bailey ◽

Rosalind King ◽

Simon Holford ◽

Joshua Sage ◽

Martin Hand ◽

...

Keyword(s):

Regional Scale ◽

Sedimentary Basins ◽

In Situ Stress ◽

Natural Fracture ◽

Enhanced Geothermal Systems ◽

Structural Development ◽

Geothermal Systems ◽

Stress Regime ◽

Orientation Data

Declining conventional hydrocarbon reserves have triggered exploration towards unconventional energy, such as CSG, shale gas and enhanced geothermal systems. Unconventional play viability is often heavily dependent on the presence of secondary permeability in the form of interconnected natural fracture networks that commonly exert a prime control over permeability due to low primary permeabiliy of in situ rock units. Structural permeability in the Northern Perth, SA Otway, and Northern Carnarvon basins is characterised using an integrated geophysical and geological approach combining wellbore logs, seismic attribute analysis and detailed structural geology. Integration of these methods allows for the identification of faults and fractures across a range of scales (millimetre to kilometre), providing crucial permeability information. New stress orientation data is also interpreted, allowing for stress-based predictions of fracture reactivation. Otway Basin core shows open fractures are rarer than image logs indicate; this is due to the presence of fracture-filling siderite, an electrically conductive cement that may cause fractures to appear hydraulically conductive in image logs. Although the majority of fractures detected are favourably oriented for reactivation under in situ stresses, fracture fill primarily controls which fractures are open, demonstrating that lithological data is often essential for understanding potential structural permeability networks. The Carnarvon Basin is shown to host distinct variations in fracture orientation attributable to the in situ stress regime, regional tectonic development and local structure. A detailed understanding of the structural development, from regional-scale (hundreds of kilometres) down to local-scale (kilometres), is demonstrated to be of importance when attempting to understand structural permeability.

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Structural development of the Snow Lake Allochthon and its role in the evolution of the southeastern Trans-Hudson Orogen in Manitoba, central Canada

Canadian Journal of Earth Sciences ◽

10.1139/e99-014 ◽

1999 ◽

Vol 36 (11) ◽

pp. 1881-1899 ◽

Cited By ~ 14

Author(s):

Jürgen Kraus ◽

Paul F Williams

Keyword(s):

Structural Development ◽

Southeastern Part ◽

External Zone ◽

Local Boundary ◽

Tectonic Model ◽

Adjacent Part ◽

Central Canada ◽

Tectonic Transport ◽

The One ◽

Superior Craton

The Snow Lake Allochthon is a zone of tectonic interleaving of sedimentary rocks of an inverted marginal basin (Kisseynew Domain) with island-arc and oceanic rocks. It is located in the southeastern part of the exposed internal zone of the Paleoproterozoic Trans-Hudson Orogen in Manitoba, Canada, near the external zone (Superior collision zone or Thompson Belt), which constitutes the local boundary between the Trans-Hudson Orogen and the Archean Superior Craton. The Snow Lake Allochthon formed, was deformed, and was metamorphosed up to high grade at low to medium pressure during the Hudsonian orogeny as a result of the collision of Archean cratons ~1.84-1.77 Ga. Four generations of folds (F1-F4) that formed in at least three successive kinematic frames over a period of more than 30 Ma are described. Isoclinal to transposed southerly verging F1-2 structures are refolded by large, open to tight F3 folds and, locally, by open to tight F4 folds. The axes of the F1-2 folds are parallel or near parallel to the axes of F3 folds, owing to progressive reorientation of the F1-2 axes during south- to southwest-directed tectonic transport, followed by F3 refolding around the previous linear anisotropy. A tectonic model is presented that reconciles the distinct tectono-metamorphic developments in the Snow Lake Allochthon and the adjacent part of the Kisseynew Domain on the one hand, and in the Thompson Belt on the other, during final collision of the Trans-Hudson Orogen with the Superior Craton.

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Pattern and origin of the present-day tectonic stress in the Australian sedimentary basins

ASEG Extended Abstracts ◽

10.1071/aseg2016ab275 ◽

2016 ◽

Vol 2016 (1) ◽

pp. 1-5 ◽

Cited By ~ 1

Author(s):

Mojtaba Rajabi ◽

Mark Tingay

Keyword(s):

Sedimentary Basins ◽

Tectonic Stress

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The Role of GIS in the Interdisciplinary Investigations at Olorgesailie, Kenya, a Pleistocene Archaeological Locality

Anthropology, Space, and Geographic Information Systems ◽

10.1093/oso/9780195085754.003.0015 ◽

1996 ◽

Author(s):

Richard Potts ◽

Daniel Cole

Keyword(s):

Spatial Databases ◽

Regional Scale ◽

Interdisciplinary Studies ◽

Rift System ◽

East African Rift System ◽

Early Hominid ◽

Gis Applications ◽

Basement Rocks ◽

Complex Structural ◽

African Rift

A geographic information system is an ideal tool for use in interdisciplinary studies because it provides automated means of linking and relating different spatial databases. In this paper we discuss GIS applications to ongoing archaeological and paleoecological studies at Olorgesailie, an early hominid archaeological locality in the rift valley of southern Kenya and one of the most noted Acheulian handaxe sites worldwide (Isaac 1977). The questions being asked in early hominid archaeology require thinking beyond individual artifacts and site excavations to broader spatial scales within welldefined time intervals (or chronostratigraphic units) (Blumenschine and Masao 1991; Potts 1991). The sedimentary exposures at Olorgesailie permit the smallest spatial scale of individual artifacts and fossils to be integrated with regional-scale studies. Since many of the GIS applications are still in initial form, the purpose here is largely to illustrate the conceptual framework by which GIS integrates the analysis of spatial data at varying geographic scales in the Olorgesailie basin. Covering over 4000 km in length, the African Rift System trends southward from the Afar Triangle in the Red Sea region to south of the Zambezi River in Zambia. The numerous continental rift basins that make up the rift system have a complex structural and volcanic history. For most of its length, the African Rift traverses Ethiopia, Kenya, and Tanzania. The rift is divisible into eastern and western portions, which merge into a broad faulted region in northern Tanzania (Baker et al. 1972). Between the eastern and western rifts, occupying portions of Uganda, Tanzania, and northern Kenya, is an uplifted plateau 1000 to 1200 m in elevation. Uplifted, elongated domal structures located in Ethiopia and Kenya form the structural base from which the East African Rift System has developed. The rocks that make up this shield complex are Precambrian gneisses, quartzites, and schists. In addition to intrusions by dikes and plutons, these basement rocks have been altered by partial melting and metamorphism. Significant though episodic uplift of the Kenyan dome and its flanks during the late Cretaceous and middle and late Tertiary contributed to the development of a graben structure (Baker 1986; Baker et al. 1972).

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Transient Thermal Effects in Sedimentary Basins with Normal Faults and Magmatic Sill Intrusions—A Sensitivity Study

Geosciences ◽

10.3390/geosciences9040160 ◽

2019 ◽

Vol 9 (4) ◽

pp. 160 ◽

Cited By ~ 3

Author(s):

Magnhild Sydnes ◽

Willy Fjeldskaar ◽

Ivar Grunnaleite ◽

Ingrid Fjeldskaar Løtveit ◽

Rolf Mjelde

Keyword(s):

Physical Properties ◽

Thermal Effects ◽

Sedimentary Basins ◽

Sensitivity Study ◽

Fault Slip ◽

Structural Development ◽

Potential Source Rock ◽

Magmatic Intrusions ◽

Transient Thermal ◽

Magmatic Sill

Magmatic intrusions affect the basin temperature in their vicinity. Faulting and physical properties of the basin may influence the magnitudes of their thermal effects and the potential source rock maturation. We present results from a sensitivity study of the most important factors affecting the thermal history in structurally complex sedimentary basins with magmatic sill intrusions. These factors are related to faulting, physical properties, and restoration methods: (1) fault displacement, (2) time span of faulting and deposition, (3) fault angle, (4) thermal conductivity and specific heat capacity, (5) basal heat flow and (6) restoration method. All modeling is performed on the same constructed clastic sedimentary profile containing one normal listric fault with one faulting event. Sills are modeled to intrude into either side of the fault zone with a temperature of 1000 °C. The results show that transient thermal effects may last up to several million years after fault slip. Thermal differences up to 40 °C could occur for sills intruding at time of fault slip, to sills intruding 10 million years later. We have shown that omitting the transient thermal effects of structural development in basins with magmatic intrusions may lead to over- or underestimation of the thermal effects of magmatic intrusions and ultimately the estimated maturation.

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Seismic detection of rockslides at regional scale: examples from the Eastern Alps and feasibility of kurtosis-based event location

Earth Surface Dynamics ◽

10.5194/esurf-6-955-2018 ◽

2018 ◽

Vol 6 (4) ◽

pp. 955-970 ◽

Cited By ~ 9

Author(s):

Florian Fuchs ◽

Wolfgang Lenhardt ◽

Götz Bokelmann ◽

Keyword(s):

Large Scale ◽

Seismic Velocity ◽

Regional Scale ◽

Vertical Component ◽

Mean Amplitude ◽

Velocity Model ◽

Automatic Processing ◽

Eastern Alps ◽

Seismic Records ◽

Seismic Networks

Abstract. Seismic records can provide detailed insight into the mechanisms of gravitational mass movements. Catastrophic events that generate long-period seismic radiation have been studied in detail, and monitoring systems have been developed for applications on a very local scale. Here we demonstrate that similar techniques can also be applied to regional seismic networks, which show great potential for real-time and large-scale monitoring and analysis of rockslide activity. This paper studies 19 moderate-sized to large rockslides in the Eastern Alps that were recorded by regional seismic networks within distances of a few tens of kilometers to more than 200 km. We develop a simple and fully automatic processing chain that detects, locates, and classifies rockslides based on vertical-component seismic records. We show that a kurtosis-based onset picker is suitable to detect the very emergent onsets of rockslide signals and to locate the rockslides within a few kilometers from the true origin using a grid search and a 1-D seismic velocity model. Automatic discrimination between rockslides and local earthquakes is possible by a combination of characteristic parameters extracted from the seismic records, such as kurtosis or maximum-to-mean amplitude ratios. We attempt to relate the amplitude of the seismic records to the documented rockslide volume and reveal a potential power law in agreement with earlier studies. Since our approach is based on simplified methods we suggest and discuss how each step of the automatic processing could be expanded and improved to achieve more detailed results in the future.

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Geology and petroleum prospectivity of the deepwater Otway and Sorell basins: new insights from an integrated regional study

The APPEA Journal ◽

10.1071/aj10072 ◽

2011 ◽

Vol 51 (2) ◽

pp. 692 ◽

Cited By ~ 3

Author(s):

Andrew Stacey ◽

Cameron Mitchell ◽

Goutam Nayak ◽

Heike Struckmeyer ◽

Michael Morse ◽

...

Keyword(s):

Continental Margin ◽

Regional Scale ◽

Rift System ◽

Aeromagnetic Data ◽

Regional Study ◽

Sequence Stratigraphic ◽

Petroleum Systems ◽

Tectonic History ◽

Complex Structural ◽

Potential Field Modelling

The frontier deepwater Otway and Sorell basins lie offshore of southwestern Victoria and western Tasmania at the eastern end of Australia’s Southern Rift System. The basins developed during rifting and continental separation between Australia and Antarctica from the Cretaceous to Cenozoic. The complex structural and depositional history of the basins reflects their location in the transition from an orthogonal–obliquely rifted continental margin (western–central Otway Basin) to a transform continental margin (southern Sorell Basin). Despite good 2D seismic data coverage, these basins remain relatively untested and their prospectivity poorly understood. The deepwater (> 500 m) section of the Otway Basin has been tested by two wells, of which Somerset–1 recorded minor gas shows. Three wells have been drilled in the Sorell Basin, where minor oil shows were recorded near the base of Cape Sorell–1. As part of the federal government-funded Offshore Energy Security Program, Geoscience Australia has acquired new aeromagnetic data and used open file seismic datasets to carry out an integrated regional study of the deepwater Otway and Sorell basins. Structural interpretation of the new aeromagnetic data and potential field modelling provide new insights into the basement architecture and tectonic history, and highlights the role of pre-existing structural fabric in controlling the evolution of the basins. Regional scale mapping of key sequence stratigraphic surfaces across the basins, integration of the regional structural analysis, and petroleum systems modelling have resulted in a clearer understanding of the tectonostratigraphic evolution and petroleum prospectivity of this complex basin system.

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Numerical Modelling of Salt-Related Stress Decoupling in Sedimentary Basins–Motivated by Observational Data from the North German Basin

Geosciences ◽

10.3390/geosciences9010019 ◽

2018 ◽

Vol 9 (1) ◽

pp. 19

Author(s):

Steffen Ahlers ◽

Tobias Hergert ◽

Andreas Henk

Keyword(s):

Observational Data ◽

Sedimentary Cover ◽

Sedimentary Basins ◽

Stress Fields ◽

Salt Diapir ◽

Model Parameters ◽

Salt Layer ◽

Stress Changes ◽

Stress Orientations ◽

Mechanical Decoupling

A three dimensional (3D) finite element model is used to study the conditions leading to mechanical decoupling at a salt layer and vertically varying stress fields in salt-bearing sedimentary basins. The study was inspired by observational data from northern Germany showing stress orientations varying up to 90° between the subsalt and the suprasalt layers. Parameter studies address the role of salt viscosity and salt topology on how the plate boundary forces acting at the basement level affect the stresses in the sedimentary cover above the salt layer. Modelling results indicate that mechanical decoupling occurs for dynamic salt viscosities lower than 1021 Pa·s, albeit this value depends on the assumed model parameters. In this case, two independent stress fields coexist above and below the salt layer, differing in tectonic stress regime and/or stress orientation. Thereby, stresses in the subsalt domain are dominated by the shortening applied, whereas in the suprasalt section they are controlled by the local salt topology. For a salt diapir, the orientation of the maximum horizontal stress changes from a circular pattern above to a radial pattern adjacent to the diapir. The study shows the value of geomechanical models for stress prediction in salt-bearing sedimentary basins providing a continuum mechanics–based explanation for the variable stress orientations observed.

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Thermal signature of the lithosphere below sedimentary basins in extensional, compressive and transform settings

10.5194/egusphere-egu2020-22518 ◽

2020 ◽

Author(s):

Magdalena Scheck-Wenderoth ◽

Judith Bott ◽

Mauro Cacace ◽

Denis Anikiev ◽

Maria Laura Gomez Dacal ◽

...

Keyword(s):

Tectonic Setting ◽

Internal Heat ◽

Sedimentary Basins ◽

Rift System ◽

Upper Rhine Graben ◽

East African Rift System ◽

Forming Mechanism ◽

Passive Margins ◽

The North ◽

Thermal Signature

The configuration of the lithosphere below sedimentary basins varies in response to the basin-forming mechanism, the lifetime of the causative stress fields and the lithological heterogeneity inherited from pre-basin tectonic events. Accordingly, the deep thermal configuration is a function of the tectonic setting, the time since the thermal disturbance occurred and the internal heat sources within the lithosphere. We compare deep thermal configurations in different settings based on data-constrained 3D lithosphere-scale thermal models that consider both geological and geophysical observations and physical processes of heat transfer. The results presented come from a varied range of tectonic settings including: (1) the extensional settings of the Upper Rhine Graben and the East African Rift System, where we show that rifts can be hot for different reasons; (2) the North and South Atlantic passive margins, demonstrating that magma-rich passive margins can be comparatively hot or cold depending on the thermo-tectonic age; (3) the Alps, where we find that foreland basins are influenced by the conductive properties and heat-producing units of the adjacent orogen; and (4)the Sea of Marmara, along the westernmost sector of the North Anatolian Fault Zone, that suggest strike-slip basins may be thermally segmented.

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Rift systems of the East Siberian basin, Arctic region

10.5194/egusphere-egu2020-8551 ◽

2020 ◽

Author(s):

Nickolay Zhukov ◽

Anatoly Nikishin ◽

Eugene Petrov

Keyword(s):

Continental Margin ◽

Large Scale ◽

Block Structure ◽

Sedimentary Basins ◽

Rift System ◽

Northwestern Part ◽

Gravitational Fields ◽

Stage Of Development ◽

East Siberian Sea ◽

Seismic Lines

The growing interest of geoscientists to the Eastern Arctic shelf is caused one of the most important problems of the present time &#8211; the creation of a tectonic model for assessing the hydrocarbon potential of the Eastern Arctic basins. In this time, over the past decade, the study of the East Siberian sea seismic lines have increased. Now, we operated a new seismic data, the interpretation of which gives the key to understanding the structure of the East Siberian continental margin.This paper presents an analysis of the tectonic structure and geological history of the shelf of the East Siberian continental margin based on the interpretation of seismic lines in conjunction with geological information.The modern ideas of the East Arctic rift tectonic evolution and formation of sedimentary basins over the entire East Siberian shelf resulted from the large-scale tectonic and magmatism events took place and the intense rifting or stretching phase widespread the entire shelf in the Albian-Aptian.The East Siberian basin includes the main structural elements, formed in a postcollisional destructive stage of development &#8211; the New Siberian rift, the De Long uplift, the Zhokhov Foredeep basin, the Melville trough, the Baranov rise, the Pegtymel trough, the Shelagskoe rise.The New Siberian rift is located between the elevations of the New Siberian Islands and the archipelago De Long. Rift extends in a southeast direction from the East-Anisin Trough deflection to the Islands of Faddeev Island and New Siberia Islands. The New Siberian rift is a bright negative structural element and clearly stands out on the maps of the anomalous magnetic and gravitational fields, contrasting with the positive anomalies of surrounding rises and ridges.De Long Plateau is a large positive structure. The uplift boundaries and internal structure are clearly visible in the gravitational and magnetic fields. The magnetic anomaly expressed in the De long, it is a typical for the areas of development of volcanogenic formations and basalts trap magmatism.The East Siberian Rift System located from the northwestern part of the De long Plateau to the eastern part of the North Chukchi basin. System includes the Melville trough in the southern part of the East Siberian Sea. The reflector packages on seismic lines in the De Long Plateau and The East Siberian Rift System indicate that continental rifting occurred over the mantle plum.The length of the Melville trough is a 350-370 km; with a width of 100-150 km. Trough is the symmetrical deflection consists of two narrow rifts separated by a rise.The eastern branch of the rift system of the Melville trough joins the Baranov rise. The Baranov rise has a block structure with the geometry of which is similar to the block structure of the De-Long Plateau.The Dremkhed trough is a deep rift structure transitional between the East Siberian and North Chukchi basins, the thickness of the sedimentary cover in central part of section is 7000 ms.The study was funded by RFBR project - 18-05-70011.

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