scholarly journals Evolution of a Normal Fault System, northern Graben, Taranaki Basin, New Zealand

2021 ◽  
Author(s):  
◽  
Hamish Cameron
Keyword(s):  
New Zealand ◽  
Seismic Reflection ◽  
Normal Fault ◽  
Growth Patterns ◽  
Fault System ◽  
Normal Faults ◽  
3D Seismic ◽  
Fault Evolution ◽  
Migration Pathways ◽  
Insight Into

<p>This study investigates the evolution (from initiation to inactivity) of a normal fault system in proximity to active petroleum systems within the Taranaki Basin, New Zealand. The aim of this research is to understand the evolution, interaction, and in some cases, death of normal faults in a region undergoing progressive regional extension. This research provides insight into the geometry, development, and displacement history of new and reactivated normal fault evolution through interpretation of industry standard seismic reflection data at high spatial and temporal resolution. Insight into normal fault evolution provides information on subsidence rates and potential hydrocarbon migration pathways.  Twelve time horizons between 1.2 and 35 Ma have been mapped throughout 1670 square kilometres of the Parihaka and Toro 3D seismic reflection surveys. Fault displacement analysis and backstripping have been used to determine the main phases of fault activity, fault growth patterns, and maximum Displacement/Length ratios. The timing, geometry, and displacement patterns for 110 normal faults with displacements >20 m have been interpreted and analysed using Paradigm SeisEarth and TrapTester 6 seismic interpretation and fault analysis software platforms.  Normal faults within the Parihaka and Toro 3D seismic surveys began developing at ˜11 Ma, with the largest faults accruing up to 1500 m of displacement in <10 Myr (mean throw displacement rate of 0.15mm/yr). Approximately 50% of the 110 mapped faults are associated with pre-existing normal faults and have typical cumulative displacements of ˜20 – 1000 m, with strike parallel lengths of <1 – 23 km. In contrast, new faults have typically greater displacements of 20 – 1400 m, and are generally longer with, with strike parallel lengths of ˜1 – 33 km.   New faults were the first faults within the system to become inactive when strain rates decreased from 0.06 – 0.03 between 3.6 and 3.0 Ma. Eight of the largest faults with > 1000 m cumulative displacement reach the seafloor and are potentially active at present day. An earthquake on one of these faults could be expected to produce MW 2.2 based on the maximum strike-parallel length of the fault plane.</p>

scholarly journals Evolution of a Normal Fault System, northern Graben, Taranaki Basin, New Zealand

2021 ◽  
Author(s):  
◽  
Hamish Cameron
Keyword(s):  
New Zealand ◽  
Seismic Reflection ◽  
Normal Fault ◽  
Growth Patterns ◽  
Fault System ◽  
Normal Faults ◽  
3D Seismic ◽  
Fault Evolution ◽  
Migration Pathways ◽  
Insight Into

<p>This study investigates the evolution (from initiation to inactivity) of a normal fault system in proximity to active petroleum systems within the Taranaki Basin, New Zealand. The aim of this research is to understand the evolution, interaction, and in some cases, death of normal faults in a region undergoing progressive regional extension. This research provides insight into the geometry, development, and displacement history of new and reactivated normal fault evolution through interpretation of industry standard seismic reflection data at high spatial and temporal resolution. Insight into normal fault evolution provides information on subsidence rates and potential hydrocarbon migration pathways.  Twelve time horizons between 1.2 and 35 Ma have been mapped throughout 1670 square kilometres of the Parihaka and Toro 3D seismic reflection surveys. Fault displacement analysis and backstripping have been used to determine the main phases of fault activity, fault growth patterns, and maximum Displacement/Length ratios. The timing, geometry, and displacement patterns for 110 normal faults with displacements >20 m have been interpreted and analysed using Paradigm SeisEarth and TrapTester 6 seismic interpretation and fault analysis software platforms.  Normal faults within the Parihaka and Toro 3D seismic surveys began developing at ˜11 Ma, with the largest faults accruing up to 1500 m of displacement in <10 Myr (mean throw displacement rate of 0.15mm/yr). Approximately 50% of the 110 mapped faults are associated with pre-existing normal faults and have typical cumulative displacements of ˜20 – 1000 m, with strike parallel lengths of <1 – 23 km. In contrast, new faults have typically greater displacements of 20 – 1400 m, and are generally longer with, with strike parallel lengths of ˜1 – 33 km.   New faults were the first faults within the system to become inactive when strain rates decreased from 0.06 – 0.03 between 3.6 and 3.0 Ma. Eight of the largest faults with > 1000 m cumulative displacement reach the seafloor and are potentially active at present day. An earthquake on one of these faults could be expected to produce MW 2.2 based on the maximum strike-parallel length of the fault plane.</p>

scholarly journals A snapshot of the earliest stages of normal fault development

2021 ◽  
Author(s):  
Ahmed Alghuraybi ◽  
Rebecca Bell ◽  
Chris Jackson
Keyword(s):  
Seismic Reflection ◽  
Spatial Scales ◽  
Normal Fault ◽  
Normal Faults ◽  
3D Seismic ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Temporal And Spatial ◽  
Fault Growth ◽  
Lateral Propagation

Despite decades of study, models for the growth of normal faults lack a temporal framework within which to understand how these structures accumulate displacement and lengthen through time. Here, we use borehole and high-quality 3D seismic reflection data from offshore Norway to quantify the lateral (0.2-1.8 mmyr-1) and vertical (0.004-0.02 mmyr-1) propagation rates (averaged over 12-44 Myr) for several long (up to 43 km), moderate displacement (up to 225 m) layer-bound faults that we argue provide a unique, essentially ‘fossilised’ snapshot of the earliest stage of fault growth. We show that lateral propagation rates are 90 times faster than displacement rates during the initial 25% of their lifespan suggesting that these faults lengthened much more rapidly than they accrued displacement. Although these faults have slow displacement rates compared with data compiled from 30 previous studies, they have comparable lateral propagation rates. This suggests that the unusual lateral propagation to displacement rate ratio is likely due to fault maturity, which highlights a need to document both displacement and lateral propagation rates to further our understanding of how faults evolve across various temporal and spatial scales.

Seismic reflection imaging of the low-angle Panamint Valley normal fault system, eastern California, USA

2020 ◽  
Author(s):  
Ryan Gold ◽  
William Stephenson ◽  
Richard Briggs ◽  
Christopher DuRoss ◽  
Eric Kirby ◽  
...  
Keyword(s):  
Seismic Reflection ◽  
Late Quaternary ◽  
Hazard Analysis ◽  
Hanging Wall ◽  
Normal Fault ◽  
Alluvial Fan ◽  
P Wave ◽  
Fault System ◽  
Normal Faults ◽  
High Angle

&lt;p&gt;A fundamental question in seismic hazard analysis is whether &lt;30&amp;#186;-dipping low-angle normal faults (LANFs) slip seismogenically. In comparison to more steeply dipping (45-60&amp;#186;) normal faults, LANFs have the potential to produce stronger shaking given increased potential rupture area in the seismogenic crust and increased proximity to manmade structures built on the hanging wall. While inactive LANFs have been documented globally, examples of seismogenically active LANFs are limited. The western margin of the Panamint Range in eastern California is defined by an archetype LANF that dips west beneath Panamint Valley and has evidence of Quaternary motion. In addition, high-angle dextral-oblique normal faults displace mid-to-late Quaternary alluvial fans near the range front. To image shallow (&lt;1 km depth), crosscutting relationships between the low- and high-angle faults along the range front, we acquired two high-resolution P-wave seismic reflection profiles. The northern ~4.7-km profile crosses the 2-km-wide Wildrose Graben and the southern ~1.1-km profile extends onto the Panamint Valley playa, ~7.5 km S of Ballarat, CA. The profile across the Wildrose Graben reveals a robust, low-angle reflector that likely represents the LANF separating Plio-Pleistocene alluvial fanglomerate and pre-Cambrian meta-sedimentary deposits. High-angle faults interpreted in the seismic profile correspond to fault scarps on Quaternary alluvial fan surfaces. Interpretation of the reflection data suggests that the high-angle faults vertically displace the LANF up to 70 m within the Wildrose Graben. Similarly, the profile south of Ballarat reveals a low-angle reflector, which appears both rotated and displaced up to 260 m by high-angle faults. These results suggest that near the Panamint range front, the high-angle faults are the dominant late Quaternary structures. We conclude that, at least at shallow (&lt;1 km) depths, the LANF we imaged is not seismogenically active today.&lt;/p&gt;

scholarly journals A Multi-Frequency Acoustic  Investigation of Seafloor  Methane Seep Sites at  Omakere Ridge, Hikurangi  Margin, New Zealand

2021 ◽  
Author(s):  
◽  
Thomas Vasilios Golding
Keyword(s):  
New Zealand ◽  
Reflection Coefficient ◽  
Gas Hydrate ◽  
Seismic Reflection ◽  
Authigenic Carbonate ◽  
3D Seismic ◽  
Methane Seep ◽  
Backscatter Intensity ◽  
Seismic Amplitude ◽  
Migration Pathways

<p>Omakere Ridge is an anticlinal thrust ridge in water depths of 1100–1700mon the Hikurangi Margin, east of the North Island of New Zealand, and is an area of active seafloor methane seepage associated with an extensive gas hydrate province. Methane seep sites on the Hikurangi Margin are characterised by localised buildups of authigenic carbonate and chemosynthetic seep fauna that exist on a seafloor otherwise characterised by soft, muddy sediments and provide a unique window into the workings of the gas hydrate system. Seafloor methane seeps sites on Omakere Ridge have been successfully imaged using three newly-acquired acoustic datasets: a P-CableTM high-resolution 3D seismic reflection dataset (60 Hz); a multibeam sonar backscatter dataset (12 kHz); and a ParasoundTM subbottom profiler dataset (4 kHz). Seafloor seismic amplitude and similarity maps have been derived from a preliminary shipboard post-stack migrated data cube. A pronounced acquisition artifact is manifest in the seafloor horizon slice as high- and low-amplitude stripes that alternate periodically in the crossline direction. This artifact has been removed from the seafloor horizon slice using 2D spatial frequency filtering, followed by direct sampling and stochastic removal of the very-low-frequency components in the spatial domain. The seismic amplitude map has then been transformed into a calibrated seafloor reflection coefficient map. Sonar backscatter mosaics have been created after correcting for beam pattern effects and angular variation in backscatter after taking into account the bathymetry. Several backscatter mosaics were incorporated into a stacked mosaic over the study area to attenuate random noise. The ParasoundTM sub-bottom profiler data were processed to display instantaneous amplitude and separated into 43 lines over the study area. Comparison of 3D seismic attributes, multibeam backscatter intensity and shallow subsurface reflection characteristics provides new insights into the previously unknown extent of authigenic carbonate build-ups, methane migration pathways and seep initiation mechanisms at five seep sites on Omakere Ridge. Areas of high seafloor 3D seismic reflection coefficient and high multibeam backscatter intensity are interpreted as carbonate formations of at least 6–7 m thickness, while areas exhibiting low seismic reflection coefficient and moderate/high sonar backscatter intensity are interpreted as areas where the carbonates are less developed. Anomalous high-amplitude subsurface reflections beneath the seeps in the ParasoundTM data are interpreted as buried carbonates and may indicate a previously unknown earlier phase of seepage at Omakere Ridge, but could also be caused by gas or gas hydrates. The extent of authigenic carbonates is directly related to the duration of seepage and thus provides a new proxy for the chronology of seepage at Omakere Ridge, which has proved consistent with an existing hypothesis based on the abundance of deceased and live chemosynthetic fauna at the seep sites.</p>

scholarly journals A Multi-Frequency Acoustic  Investigation of Seafloor  Methane Seep Sites at  Omakere Ridge, Hikurangi  Margin, New Zealand

2021 ◽  
Author(s):  
◽  
Thomas Vasilios Golding
Keyword(s):  
New Zealand ◽  
Reflection Coefficient ◽  
Gas Hydrate ◽  
Seismic Reflection ◽  
Authigenic Carbonate ◽  
3D Seismic ◽  
Methane Seep ◽  
Backscatter Intensity ◽  
Seismic Amplitude ◽  
Migration Pathways

<p>Omakere Ridge is an anticlinal thrust ridge in water depths of 1100–1700mon the Hikurangi Margin, east of the North Island of New Zealand, and is an area of active seafloor methane seepage associated with an extensive gas hydrate province. Methane seep sites on the Hikurangi Margin are characterised by localised buildups of authigenic carbonate and chemosynthetic seep fauna that exist on a seafloor otherwise characterised by soft, muddy sediments and provide a unique window into the workings of the gas hydrate system. Seafloor methane seeps sites on Omakere Ridge have been successfully imaged using three newly-acquired acoustic datasets: a P-CableTM high-resolution 3D seismic reflection dataset (60 Hz); a multibeam sonar backscatter dataset (12 kHz); and a ParasoundTM subbottom profiler dataset (4 kHz). Seafloor seismic amplitude and similarity maps have been derived from a preliminary shipboard post-stack migrated data cube. A pronounced acquisition artifact is manifest in the seafloor horizon slice as high- and low-amplitude stripes that alternate periodically in the crossline direction. This artifact has been removed from the seafloor horizon slice using 2D spatial frequency filtering, followed by direct sampling and stochastic removal of the very-low-frequency components in the spatial domain. The seismic amplitude map has then been transformed into a calibrated seafloor reflection coefficient map. Sonar backscatter mosaics have been created after correcting for beam pattern effects and angular variation in backscatter after taking into account the bathymetry. Several backscatter mosaics were incorporated into a stacked mosaic over the study area to attenuate random noise. The ParasoundTM sub-bottom profiler data were processed to display instantaneous amplitude and separated into 43 lines over the study area. Comparison of 3D seismic attributes, multibeam backscatter intensity and shallow subsurface reflection characteristics provides new insights into the previously unknown extent of authigenic carbonate build-ups, methane migration pathways and seep initiation mechanisms at five seep sites on Omakere Ridge. Areas of high seafloor 3D seismic reflection coefficient and high multibeam backscatter intensity are interpreted as carbonate formations of at least 6–7 m thickness, while areas exhibiting low seismic reflection coefficient and moderate/high sonar backscatter intensity are interpreted as areas where the carbonates are less developed. Anomalous high-amplitude subsurface reflections beneath the seeps in the ParasoundTM data are interpreted as buried carbonates and may indicate a previously unknown earlier phase of seepage at Omakere Ridge, but could also be caused by gas or gas hydrates. The extent of authigenic carbonates is directly related to the duration of seepage and thus provides a new proxy for the chronology of seepage at Omakere Ridge, which has proved consistent with an existing hypothesis based on the abundance of deceased and live chemosynthetic fauna at the seep sites.</p>

Normal fault growth and segment linkage in a gravitationally detached delta system: evidence from 3D seismic reflection data from the Ceduna Sub-basin, Great Australian Bight

2015 ◽  
Vol 55 (2) ◽  
pp. 467
Author(s):  
Alexander Robson ◽  
Rosalind King ◽  
Simon Holford
Keyword(s):  
Seismic Reflection ◽  
Fault Plane ◽  
Structural Evolution ◽  
Normal Fault ◽  
Fault System ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Listric Fault ◽  
Dip Angle ◽  
Fault Growth

The authors used three-dimensional (3D) seismic reflection data from the central Ceduna Sub-Basin, Australia, to establish the structural evolution of a linked normal fault assemblage at the extensional top of a gravitationally driven delta system. The fault assemblage presented is decoupled at the base of a marine mud from the late Albian age. Strike-linkage has created a northwest–southeast oriented assemblage of normal fault segments and dip-linkage through Santonian strata, which connects a post-Santonian normal fault system to a Cenomanian-Santonian listric fault system. Cenomanian-Santonian fault growth is on the kilometre scale and builds an underlying structural grain, defining the geometry of the post-Santonian fault system. A fault plane dip-angle model has been created and established through simplistic depth conversion. This converts throw into fault plane dip-slip displacement, incorporating increasing heave of a listric fault and decreasing in dip-angle with depth. The analysis constrains fault growth into six evolutionary stages: early Cenomanian nucleation and radial growth of isolated fault segments; linkage of fault segments by the latest Cenomanian; latest Santonian Cessation of fault growth; erosion and heavy incision during the continental break-up of Australia and Antarctica (c. 83 Ma); vertically independent nucleation of the post-Santonian fault segments with rapid length establishment before significant displacement accumulation; and, continued displacement into the Cenozoic. The structural evolution of this fault system is compatible with the isolated fault model and segmented coherent fault model, indicating that these fault growth models do not need to be mutually exclusive to the growth of normal fault assemblages.

Evolution of a Normal Fault System Along Eastern Gondwana, New Zealand

Tectonics ◽  
2020 ◽  
Vol 39 (10) ◽  
Author(s):  
T. R. Sahoo ◽  
A. Nicol ◽  
G. H. Browne ◽  
D. P. Strogen
Keyword(s):  
New Zealand ◽  
Normal Fault ◽  
Fault System

Basement-involved inversion at the Appalachian structural front, western Newfoundland: an interpretation of seismic reflection data with implications for petroleum prospectivity

2004 ◽  
Vol 52 (3) ◽  
pp. 215-233 ◽  
Author(s):  
Glen S. Stockmal ◽  
Art Slingsby ◽  
John W.F. Waldron
Keyword(s):  
Seismic Reflection ◽  
Hanging Wall ◽  
Normal Fault ◽  
Hydrocarbon Exploration ◽  
Normal Faults ◽  
Apparent Magnitude ◽  
Seismic Reflection Data ◽  
The Public ◽  
Reflection Data ◽  
New Interpretation

Abstract Recent hydrocarbon exploration in western Newfoundland has resulted in six new wells in the Port au Port Peninsula area. Port au Port No.1, drilled in 1994/95, penetrated the Cambro-Ordovician platform and underlying Grenville basement in the hanging wall of the southeast-dipping Round Head Thrust, terminated in the platform succession in the footwall of this basement-involved inversion structure, and discovered the Garden Hill petroleum pool. The most recent well, Shoal Point K-39, was drilled in 1999 to test a model in which the Round Head Thrust loses reverse displacement to the northeast, eventually becoming a normal fault. This model hinged on an interpretation of a seismic reflection survey acquired in 1996 in Port au Port Bay. This survey is now in the public domain. In our interpretation of these data, the Round Head Thrust is associated with another basement-involved feature, the northwest-dipping Piccadilly Bay Fault, which is mapped on Port au Port Peninsula. Active as normal faults in the Taconian foreland, both these faults were later inverted during Acadian orogenesis. The present reverse offset on the Piccadilly Bay Fault was previously interpreted as normal offset on the southeast-dipping Round Head Thrust. Our new interpretation is consistent with mapping on Port au Port Peninsula and north of Stephenville, where all basement-involved faults are inverted and display reverse senses of motion. It also explains spatially restricted, enigmatic reflections adjacent to the faults as carbonate conglomerates of the Cape Cormorant Formation or Daniel’s Harbour Member, units associated with inverted thick-skinned faults. The K-39 well, which targeted the footwall of the Round Head Thrust, actually penetrated the hanging wall of the Piccadilly Bay Fault. This distinction is important because the reservoir model invoked for this play involved preferential karstification and subsequent dolomitization in the footwalls of inverted thick-skinned faults. The apparent magnitude of structural inversion across the Piccadilly Bay Fault suggests other possible structural plays to the northeast of K-39.

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