scholarly journals Pre-inversion normal fault geometry controls inversion style and magnitude, Farsund Basin, offshore southern Norway

Solid Earth ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 1489-1510
Author(s):  
Thomas B. Phillips ◽  
Christopher A.-L. Jackson ◽  
James R. Norcliffe
Keyword(s):  
Late Cretaceous ◽  
Focal Point ◽  
Three Dimensional ◽  
Normal Fault ◽  
Fault System ◽  
Prior History ◽  
Plate Boundaries ◽  
Northern Margin ◽  
Long Wavelength ◽  
Structural Style

Abstract. Compressional strains may manifest along pre-existing structures within the lithosphere, far from the plate boundaries along which the causal stress is greatest. The style and magnitude of the related contraction is expressed in different ways, depending on the geometric and mechanical properties of the pre-existing structure. A three-dimensional approach is thus required to understand how compression may be partitioned and expressed along structures in space and time. We here examine how post-rift compressional strains are expressed along the northern margin of the Farsund Basin during Late Cretaceous inversion and Palaeogene–Neogene pulses of uplift. At the largest scale, stress localises along the lithosphere-scale Sorgenfrei-Tornquist Zone, where it is expressed in the upper crust as hangingwall folding, reverse reactivation of the basin-bounding normal fault, and bulk regional uplift. The geometry of the northern margin of the basin varies along strike, with a normal fault system passing eastward into an unfaulted ramp. Late Cretaceous compressive stresses, originating from the convergence between Africa, Iberia, and Europe, selectively reactivated geometrically simple, planar sections of the fault, producing hangingwall anticlines and causing long-wavelength folding of the basin fill. The amplitude of these anticlines decreases upwards due to tightening of pre-existing fault propagation folds at greater depths. In contrast, later Palaeogene–Neogene uplift is accommodated by long-wavelength folding and regional uplift of the entire basin. Subcrop mapping below a major, uplift-related unconformity and borehole-based compaction analysis show that uplift increases to the north and east, with the Sorgenfrei-Tornquist Zone representing a hinge line rather than a focal point to uplift, as was the case during earlier Late Cretaceous compression. We show how compressional stresses may be accommodated by different mechanisms within structurally complex settings. Furthermore, the prior history of a structure may also influence the mechanism and structural style of shortening that it experiences.

scholarly journals Pre-inversion normal fault geometry controls inversion style and magnitude, Farsund Basin, offshore southern Norway

2020 ◽  
Author(s):  
Thomas Brian Phillips ◽  
Christopher A.-L. Jackson ◽  
James R. Norcliffe
Keyword(s):  
Late Cretaceous ◽  
Focal Point ◽  
Three Dimensional ◽  
Normal Fault ◽  
Fault System ◽  
Prior History ◽  
Plate Boundaries ◽  
Northern Margin ◽  
Long Wavelength ◽  
Structural Style

Abstract. Inversion may localise along pre-existing structures within the lithosphere, far from the plate boundaries along which the causal stress is greatest. Inversion style and magnitude is expressed in different ways, depending on the geometric and mechanical properties of the pre-existing structure. A three-dimensional approach is thus required to understand how inversion may be partitioned and expressed along structures in space and time. We here examine how inversion is expressed along the northern margin of the Farsund Basin during Late Cretaceous inversion and Neogene uplift. At the largest scale, strain localises along the lithosphere-scale Sorgenfrei-Tornquist Zone; this is expressed in the upper crust as hangingwall folding, reverse reactivation of the basin-bounding normal fault, and bulk regional uplift. The geometry of the northern margin of the basin varies along-strike, with a normal fault system passing eastward into an unfaulted ramp. Late Cretaceous compressive stresses, originating from the Alpine Orogeny to the south, selectively reactivated geometrically simple, planar sections of the fault, producing hangingwall anticlines and causing long-wavelength folding of the basin fill. The amplitude of these anticlines decreases upwards due to tightening of pre-existing fault propagation folds at greater depths. In contrast, Neogene shortening is accommodated by long-wavelength folding and regional uplift of the entire basin. Subcrop mapping below a major, Neogene uplift-related unconformity and bore-based compaction analysis show that uplift increases to the north and east, with the Sorgenfrei-Tornquist Zone representing a hingeline to inversion rather than a focal point, as was the case during the Late Cretaceous. We show how compressional stresses may be accommodated by different inversion mechanisms within structurally complex settings. Furthermore, the prior history of a structure may also influence the mechanism and structural style of inversion that it experiences.

scholarly journals THREE-DIMENSIONAL ANALYSIS OF NORMAL FAULT ZONES IN KARDIA MINE, PTOLEMAIS BASIN, NW GREECE

2016 ◽  
Vol 50 (1) ◽  
pp. 15 ◽  
Author(s):  
E. Delogkos ◽  
T Manzocchi ◽  
C. Childs ◽  
C. Sachanidis ◽  
T. Barmpas ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Normal Fault ◽  
3D Models ◽  
Fault Zones ◽  
System Structure ◽  
Open Pit ◽  
Fault System ◽  
Zone Structure ◽  
Geological Interpretation ◽  
Lignite Mine

Six normal fault zones, with throws ranging from a few meters up to 50 m, were studied within an active, open pit, lignite mine in Ptolemais. Each fault was mapped 20 times over a period of five years because at intervals of ca. 3 months working faces are taken back between 20 and 50 m exposing fresh fault outcrops for mapping.Various resolutions of photographs and structural measurements were imported into a fully georeferenced 3D structural interpretation package, resulting in aseismic scale and outcrop resolution 3D fault volume with outcrop and panoramic photographs acting as the seismic sections in equivalent seismic surveys. Low resolution 3D models for the fault system structure at mine scale and higher-resolution 3D models for the fault zone structure were produced after geological interpretation and they can be used for qualitative and quantitative analysis.

Mesozoic salt tectonics in the Toulon Belt, Eastern Provence : Inversion of a salt-rich fault zone

2021 ◽  
Author(s):  
Vincent Wicker ◽  
Mary Ford
Keyword(s):  
Fault Zone ◽  
Early Cretaceous ◽  
Late Cretaceous ◽  
Three Dimensional ◽  
Complex Salt ◽  
Salt Diapir ◽  
Lateral Migration ◽  
Northern Flank ◽  
Northern Margin ◽  
Thickness Variations

<p>Detailed structural and stratigraphic field mapping is used to reconstruct the Jurassic to Late Cretaceous diapiric and tectonic evolution of the Toulon Fault Zone, eastern Beausset Syncline and Toulon Belt, southern France, which represents the easternmost vestige of the Pyrenean orogen in Provence. This complex salt-rich area records a complete history from Jurassic-early Cretaceous subsidence and Aptian-Albian oblique rifting to Late Cretaceous Pyrenean-Provençal shortening. Halokinetic sequences and geometries were preserved principally on the northern flank of the Mont Caume salt diapir sourced from the Upper Triassic Keuper unit. Our field observations are best explained by a model where halokinetic activity interacted with regional deviatoric stresses from early-Jurassic to Santonian/Campanian times. Halokinetic wedges of Jurassic and Early Cretaceous carbonates thin toward the diapir, recording early salt mobilisation. Inverted relics of Apto-Albian rift depocenters are aligned along the northern margin of the Toulon Belt and the adjacent Bandol belt that lies to the west.  The Turonian-Coniacian Revest depocenter developed due to localized strong asymmetrical growth of the Mont Caume diapir. The three-dimensional form and growth of the diapir controlled lateral migration of the Revest depocenter, thickness variations, progressive unconformities, and the westward increase in stratal overturning of a flap. A component of N-S compression with related accelerated halokinetic activity can explain our observations and can be considered as the earliest expression of N-S convergence in the Provencal fold belt.  Further west, the overturned Beausset klippe can be interpreted as the remnant of a megaflap on the northern flank of the Bandol diapir. The Toulon belt salt structures are excellent field analogues to others observed in the external Alps and Pyrenees.</p>

scholarly journals Workflow of Digital Field Mapping and Drone-Aided Survey for the Identification and Characterization of Capable Faults: The Case of a Normal Fault System in the Monte Nerone Area (Northern Apennines, Italy)

2020 ◽  
Vol 9 (11) ◽  
pp. 616
Author(s):  
Mauro De Donatis ◽  
Mauro Alberti ◽  
Mattia Cipicchia ◽  
Nelson Muñoz Guerrero ◽  
Giulio F. Pappafico ◽  
...  
Keyword(s):  
Central Italy ◽  
Three Dimensional ◽  
Normal Fault ◽  
Field Work ◽  
Digital Data ◽  
Fault System ◽  
Seismic Profiles ◽  
Postgraduate Students ◽  
Recent Earthquakes

Field work on the search and characterization of ground effects of a historical earthquake (i.e., the Cagli earthquake in 1781) was carried out using terrestrial and aerial digital tools. The method of capturing, organizing, storing, and elaborating digital data is described herein, proposing a possible workflow starting from pre-field project organization, through reiteration of field and intermediate laboratory work, to final interpretation and synthesis. The case of one of the most important seismic events in the area of the northern Umbria–Marche Apennines provided the opportunity to test the method with both postgraduate students and researchers. The main result of this work was the mapping of a capable normal fault system with a great number of observations, as well as a large amount of data, from difficult outcrop areas. A GIS map and a three-dimensional (3D) model, with the integration of subsurface data (i.e., seismic profiles and recent earthquake distribution information), allowed for a new interpretation of an extensional tectonic regime of this Apennines sector, similar to one of the southernmost areas of central Italy where recent earthquakes occurred on 2016.

Structure Evolution of Qinjiatun-Qindong Fault System in Lishu Subbasin

2013 ◽  
Vol 734-737 ◽  
pp. 170-177
Author(s):  
Shao Dong Qu ◽  
Chi Yang Liu ◽  
Li Jun Song ◽  
Hui Deng ◽  
Long Zhang ◽  
...  
Keyword(s):  
Fault Zone ◽  
Structure Analysis ◽  
Late Cretaceous ◽  
Seismic Data ◽  
Three Dimensional ◽  
Strike Slip ◽  
Fault System ◽  
Structure Evolution ◽  
Active Stage ◽  
Regional Stress

Three-dimensional(3-D) seismic data and structure analysis of the Lishu subasin in Songliao basin indicates that Qinjiatun fault zone is composed of two faults: East-Qin and West-Qin fault. This fault system initially formed at Huoshiling stage, peaked at Shahezi stage and faded dramatically from Yingcheng stage. The Qinjiatun fault was important in controlling strata thickness and distribution of the Huoshiling formation. Qindong fault, a typical strike-slip fault, developed relatively later, cutting the Qinjiatun fault, The major active stage was in Denglouku-Quantou stage, and weakened in the end of late Cretaceous. Qinjiatun fault zone was reversed at Denglouku stage when the regional stress went compressive, generating a structure nose that was potentially beneficial for hydrocarbon to accumulate. The strike-slip Qindong fault became active relatively later, cutting through the previous strata and proving pathways for both accumulation and effusion of hydrocarbon.

Great Plains polygonal fault system as expressed in Saskatchewan: Late Cretaceous fault initiation and graben formation

2017 ◽  
Vol 54 (5) ◽  
pp. 477-493
Author(s):  
Andy St-Onge
Keyword(s):  
Great Plains ◽  
Late Cretaceous ◽  
Three Dimensional ◽  
Fault System ◽  
Western Interior Seaway ◽  
Niobrara Formation ◽  
Near Surface ◽  
M Current ◽  
Time Extension ◽  
Polygonal Fault

An extensive polygonal fault system (PFS) has been recognized in fine-grained Late Cretaceous sediments of the Western Interior Seaway of North America. Polygonal fault systems are pervasive organizations of nontectonic faults with fault traces that coalesce to form distinctive polygonal fault patterns. Interpretation of a three-dimensional seismic dataset from southeast Saskatchewan provides insight into fault initiation, timing, and geometry for the Great Plains PFS (GPPFS). Faulting initiates in the Niobrara Formation, with the largest fault throws occurring over Early Cretaceous Viking Formation sandstone accumulations, suggesting that drape compaction over the channel sand initiated some of the faulting. Above this, faulting increases in vertical offset, and the predominant fault strike angles change in the Lea Park, Belly River, and Bearpaw formations (all homotaxial to the Pierre Shale) throughout Campanian time. By late Bearpaw time, the initially almost random fault strike orientations change to well-defined northwest–southeast- and west–east-striking grabens. These grabens have up to 20 m of throw and can be 125 m wide and 900 m long at ∼400 m current depth. Predominant graben faults are the continuation of some of the deeper PFS faults. Moreover, the grabens are present over a Campanian clinoform bed and may be interpreted to indicate Bearpaw time extension tectonics that is local or regional in scale. The PFS helps to explain near-surface faulting observed in Late Cretaceous sediments in the Western Interior Seaway and could be used as a model to help explain Late Cretaceous geology, subsurface groundwater flow, and shallow natural gas reservoir continuity.

scholarly journals Structure and kinematics of an extensional growth fold, Hadahid Fault System, Suez Rift, Egypt

2019 ◽  
Author(s):  
Christopher Aiden-Lee Jackson ◽  
Paul S Whipp ◽  
Robert Gawthorpe ◽  
Matthew M Lewis
Keyword(s):  
Structural Complexity ◽  
Surface Displacement ◽  
Normal Fault ◽  
Fault System ◽  
Length Scale ◽  
Slip Ratio ◽  
Continental Extension ◽  
Structural Style ◽  
Progressive Loss ◽  
Geometry And Kinematics

Normal faulting drives extensional growth folding of the Earth’s upper crust during continental extension, yet we know little of how fold geometry relates to the structural segmentation of the underlying fault. We use field data from the Hadahid Fault System, Suez Rift, Egypt to investigate the geometry and kinematics of a large (30 km long, up to 2.5 km displacement), exceptionally well-exposed normal fault system to test and develop models for extensional growth folding. The Hadahid Fault System comprises eight, up to 5 km long segments that are defined by unbreached or breached monoclines. These segments are soft-linked, hard-linked, or defined by a more subtle along-strike transition in overall structural style. High overlap:separation (O:S) ratios between its segments suggest the Hadahid Fault System comprises a single, now hard-linked structure at-depth. We demonstrate that a progressive loss of at-surface displacement along strike of the Hadahid Fault System results in surface-breaking faults and breached monoclines being replaced by unbreached monoclines developed above blind faults. However, shorter along-strike length-scale variations in structural style also occur, with unbreached monoclines developed between breached monoclines. The origin of this variability is unclear, but might reflect local variations in host rock material properties that drive short length-scale variations in fault propagation-to-slip ratio, and thus the timing and location of fold breaching. We show that folding is a key expression of the strain that accumulates in areas of continental extension, and argue that tectono-sedimentary models for rift development should capture the related structural complexity.

scholarly journals Structure and kinematics of an extensional growth fold, Hadahid Fault System, Suez Rift, Egypt

Solid Earth ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 1027-1051
Author(s):  
Christopher A.-L. Jackson ◽  
Paul S. Whipp ◽  
Robert L. Gawthorpe ◽  
Matthew M. Lewis
Keyword(s):  
Structural Complexity ◽  
Surface Displacement ◽  
Normal Fault ◽  
Fault System ◽  
Length Scale ◽  
Slip Ratio ◽  
Continental Extension ◽  
Structural Style ◽  
Progressive Loss ◽  
Geometry And Kinematics

Abstract. Normal faulting drives extensional growth folding of the Earth's upper crust during continental extension, yet we know little of how fold geometry relates to the structural segmentation of the underlying fault. We use field data from the Hadahid Fault System, Suez Rift, Egypt, to investigate the geometry and kinematics of a large (30 km long, up to 2.5 km displacement), exceptionally well-exposed normal fault system and to test and develop models for extensional growth folding. The Hadahid Fault System comprises eight up to 5 km long segments that are defined by unbreached or breached monoclines. These segments are soft-linked, hard-linked, or defined by a more subtle along-strike transition in overall structural style. High overlap : separation (O:S) ratios between its segments suggest the Hadahid Fault System comprises a single, now hard-linked structure at depth. We demonstrate that a progressive loss of at-surface displacement along-strike of the Hadahid Fault System results in surface-breaking faults and breached monoclines being replaced by unbreached monoclines developed above blind faults. However, shorter along-strike length-scale variations in structural style also occur, with unbreached monoclines developed between breached monoclines. The origin of this variability is unclear, but it might reflect local variations in host rock material properties that drive short length-scale variations in fault propagation-to-slip ratio, and thus the timing and location of fold breaching. We show that folding is a key expression of the strain that accumulates in areas of continental extension, arguing that tectono-sedimentary models for rift development should capture the related structural complexity.

scholarly journals Salt tectonics in the Toulon Belt : Inversion of a salt-rich fault zone

2021 ◽  
Author(s):  
Vincent Wicker ◽  
Mary Ford
Keyword(s):  
Fault Zone ◽  
Early Cretaceous ◽  
Late Cretaceous ◽  
Three Dimensional ◽  
Complex Salt ◽  
Salt Diapir ◽  
Lateral Migration ◽  
Northern Flank ◽  
Northern Margin ◽  
Thickness Variations

Detailed structural and stratigraphic field mapping is used to reconstruct the Jurassic to Late Cretaceous diapiric and tectonic evolution of the Toulon Fault Zone, eastern Beausset Syncline and Toulon Belt, southern France, which represents the easternmost vestige of the Pyrenean orogen in Provence. This complex salt-rich area records a complete history from Jurassic-early Cretaceous subsidence and Aptian-Albian oblique rifting to Late Cretaceous Pyrenean-Provençal shortening. Halokinetic sequences and geometries were preserved principally on the northern flank of the Mont Caume salt diapir sourced from the Upper Triassic Keuper unit. Our field observations are best explained by a model where halokinetic activity interacted with regional deviatoric stresses from early-Jurassic to Santonian/Campanian times. Halokinetic wedges of Jurassic and Early Cretaceous carbonates thin toward the diapir, recording early salt mobilisation. Inverted relics of Apto-Albian rift depocenters are aligned along the northern margin of the Toulon Belt and the adjacent Bandol belt that lies to the west. The Turonian-Coniacian Revest depocenter developed due to localized strong asymmetrical growth of the Mont Caume diapir. The three-dimensional form and growth of the diapir controlled lateral migration of the Revest depocenter, thickness variations, progressive unconformities, and the westward increase in stratal overturning of a flap. A component of N-S compression with related accelerated halokinetic activity can explain our observations and can be considered as the earliest expression of N-S convergence in the Provencal fold belt. Further west, the overturned Beausset klippe can be interpreted as the remnant of a megaflap on the northern flank of the Bandol diapir. The Toulon belt salt structures are excellent field analogues to others observed in the external Alps and Pyrenees.

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