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401 results found
Phillips TB, Fazlikhani H, Gawthorpe RL, et al., 2019, The influence of structural inheritance and multiphase extension on rift development, the northern North Sea, Tectonics, Vol: 38, Pages: 4099-4126, ISSN: 0278-7407
The northern North Sea rift evolved through multiple rift phases within a highly heterogeneous crystalline basement. The geometry and evolution of syn‐rift depocenters during this multiphase evolution and the mechanisms and extent to which they were influenced by preexisting structural heterogeneities remain elusive, particularly at the regional scale. Using an extensive database of borehole‐constrained 2D seismic reflection data, we examine how the physiography of the northern North Sea rift evolved throughout late Permian‐Early Triassic (RP1) and Late Jurassic‐Early Cretaceous (RP2) rift phases, and assess the influence of basement structures related to the Caledonian orogeny and subsequent Devonian extension. During RP1, the location of major depocenters, the Stord and East Shetland basins, was controlled by favorably oriented Devonian shear zones. RP2 shows a diminished influence from structural heterogeneities, activity localizes along the Viking‐Sogn graben system and the East Shetland Basin, with negligible activity in the Stord Basin and Horda Platform. The Utsira High and the Devonian Lomre Shear Zone form the eastern barrier to rift activity during RP2. Toward the end of RP2, rift activity migrated northward as extension related to opening of the proto‐North Atlantic becomes the dominant regional stress as rift activity in the northern North Sea decreases. Through documenting the evolving syn‐rift depocenters of the northern North Sea rift, we show how structural heterogeneities and prior rift phases influence regional rift physiography and kinematics, controlling the segmentation of depocenters, as well as the locations, styles, and magnitude of fault activity and reactivation during subsequent events.
Jackson C, 2019, Review of gc-2019-23 by Lacassin et al. - Rapid collaborative knowledge building via Twitter after significant geohazard events
Jackson CA-L, Whipp PS, Gawthorpe RL, et al., 2019, Structure and kinematics of an extensional growth fold, Hadahid Fault System, Suez Rift, Egypt
<jats:p>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 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, breached, or partly breached monoclines. These segments are soft- or hard-link, or defined by a more subtle 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 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. </jats:p>
Beelen D, Jackson CA-L, Patruno S, et al., 2019, The effects of differential compaction on clinothem geometries and shelf-edge trajectories, GEOLOGY, Vol: 47, Pages: 1011-1014, ISSN: 0091-7613
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- Citations: 10
Giles S, Stephen N, Jackson CA-L, 2019, Barriers to fieldwork in undergraduate geoscience degrees
<p>Fieldwork is an integral part of geoscience subjects, but changing career pathways and student demographics have major implications for the future of compulsory fieldwork. The ways in which fieldwork is taught and the learning outcomes it fulfils urgently need updating.</p>
Phillips T, Fazlikhani H, Gawthorpe R, et al., 2019, The influence of structural inheritance and multiphase extension on rift development, the northern North Sea, Publisher: EarthArXiv
The northern North Sea rift evolved through multiple rift phases within a highly heterogeneous crystalline basement. The geometry and evolution of syn‐rift depocenters during this multiphase evolution and the mechanisms and extent to which they were influenced by preexisting structural heterogeneities remain elusive, particularly at the regional scale. Using an extensive database of borehole‐constrained 2D seismic reflection data, we examine how the physiography of the northern North Sea rift evolved throughout late Permian‐Early Triassic (RP1) and Late Jurassic‐Early Cretaceous (RP2) rift phases, and assess the influence of basement structures related to the Caledonian orogeny and subsequent Devonian extension. During RP1, the location of major depocenters, the Stord and East Shetland basins, was controlled by favorably oriented Devonian shear zones. RP2 shows a diminished influence from structural heterogeneities, activity localizes along the Viking‐Sogn graben system and the East Shetland Basin, with negligible activity in the Stord Basin and Horda Platform. The Utsira High and the Devonian Lomre Shear Zone form the eastern barrier to rift activity during RP2. Toward the end of RP2, rift activity migrated northward as extension related to opening of the proto‐North Atlantic becomes the dominant regional stress as rift activity in the northern North Sea decreases. Through documenting the evolving syn‐rift depocenters of the northern North Sea rift, we show how structural heterogeneities and prior rift phases influence regional rift physiography and kinematics, controlling the segmentation of depocenters, as well as the locations, styles, and magnitude of fault activity and reactivation during subsequent events.
Claringbould JS, Bell R, Jackson CA-L, et al., 2019, Pre-breakup extension in the northern North Sea defined by complex strain partitioning and heterogeneous extension rates, Publisher: EarthArXiv
The early stages of continental rifting are accommodated by the growth of upper-crustal normal fault systems that are distributed relatively evenly across the rift width. Numerous fault systems define fault arrays, the kinematics of which are poorly understood due to a lack of regional studies drawing on high-quality subsurface data. Here we investigate the long-term (~150 Myr) growth of a rift-related fault array in the East Shetland Basin, northern North Sea, using a regionally extensive subsurface dataset comprising 2D and 3D seismic reflection surveys and 107 boreholes. We show that rift-related strain during the pre-Triassic-to-Middle Triassic was originally distributed across several sub-basins. The Middle-to-Late Triassic saw a decrease in extension rate (~14 m/Myr) as strain localized in the western part of the basin. Early Jurassic strain initially migrated eastwards, before becoming more diffuse during the main, Middle-to-Late Jurassic rift phase. The highest extension rates (~89 m/Myr) corresponded with the main rift event in the East Shetland Basin, before focusing of strain within the rift axis and ultimate abandonment of the East Shetland Basin in the Early Cretaceous. We also demonstrate marked spatial variations in timing and magnitude of slip along-strike of major fault systems during this protracted rift event. Our results imply that strain migration patterns and extension rates during the initial, pre-breakup phase of continental rifting may be more complex than previously thought; this reflects temporal and spatial changes in both thermal and mechanical properties of the lithosphere, in addition to varying extension rates.
Jackson C, McAndrew A, Hodgson D, et al., 2019, Repeated degradation and progradation of a submarine slope over geological timescales
Pichel L, Jackson C, 2019, Four-dimensional Variability of Composite Halokinetic Sequences
Sun Q, Magee C, Jackson C, et al., 2019, How do deep-water volcanoes grow?
Jackson CA-L, Whipp PS, Gawthorpe R, et al., 2019, Structure and kinematics of an extensional growth fold, Hadahid Fault System, Suez Rift, Egypt
<p>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.</p>
Kennett C, Jackson CA-L, 2019, Evaluation of internal geometries within the Miocene Utsira Formation to establish the geological concept of observed CO2 responses on 4D seismic in the Sleipner area, North Sea
<p>CO2 has been injected into the Miocene Utsira Formation at the Sleipner field in the Norwegian North Sea since October 1996. Repeat seismic surveying over the injection site in 1999, 2001, 2004 and 2006 have revealed the temporal development of the CO2 plume. However, in order to help better understand future plume development and aid in locating a new injection site the geological evolution of the Utsira Formation and its resultant stratal architecture needs further development in the greater Sleipner area. Combined used of seismic and well data show that the base of the Utsira Formation, the Middle Miocene Unconformity (MMU), is heavily deformed by soft sedimentary deformation. The source for this deformation is mass sand mobilization and injection of Skade Formation sandstones in the otherwise dominantly argillaceous sediments of the Upper Hordaland Group. Skade Formation sandstones are observed thickening in up-folded, and mounded regions of MMU, where seismic data reveal V-shaped amplitude anomalies or ‘chaotic’, noisy areas. Outside the deformed areas the Upper Hordaland Group is an otherwise flat sequence of continuous acoustic reflectors that are offset by a pervasive network of polygonal faults. Onlapping reflection terminations of lower Utsira Formation reflectors onto the deformed surface of the MMU indicate that soft sedimentary deformation occurred at a shallow depth before deposition of the Utsira Formation. Stratal elements within the sand rich (0.98 N:G) Utsira Formation include: i) south westerly dipping clinoforms, ii) erosional scours, and iii) large-scale sand waves, suggesting high depositional energy and potential erosion of (c.1 - 2.5 metre thick) shale interbeds. During deposition of the Utsira Formation differential compaction within the Upper Hordaland Group has down-folded, and rotated intra-Utsira reflectors onto underlying MMU mounded features. Løseth’s et al. (2003) and Jackson’s (2007) models for
Coleman AJ, Duffy OB, Jackson CA-L, 2019, Growth folds above propagating normal faults, EARTH-SCIENCE REVIEWS, Vol: 196, ISSN: 0012-8252
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- Citations: 22
Evans S, Jackson C, 2019, Base-Salt Relief Controls Salt-Related Deformation in the Outer Kwanza Basin, offshore Angola, Basin Research, ISSN: 0950-091X
Peron-Pinvidic G, Manatschal G, Alves T, et al., 2019, Rifted Margins: State of the Art and Future Challenges, FRONTIERS IN EARTH SCIENCE, Vol: 7
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- Citations: 61
Wu N, Jackson C, Johnson H, et al., 2019, Mass-transport complexes (MTCs) document minibasin subsidence patterns and diapir evolution in the northern Gulf of Mexico
Rodriguez C, Jackson C, Bell R, et al., 2019, Deep-water reservoir distribution on a salt-influenced slope, Santos Basin, offshore Brazil
Sun Q, Jackson C, Magee C, et al., 2019, Extrusion dynamics of deep-water volcanoes revealed by 3D seismic data, Solid Earth, ISSN: 1869-9510
Submarine volcanism accounts for c. 75% of the Earth's volcanic activity. Yet difficulties with imaging their exteriors and interiors mean the extrusion dynamics and erupted volumes of deep-water volcanoes remain poorly understood. Here, we use high-resolution 3-D seismic reflection data to examine the external and internal geometry, and extrusion dynamics of two Late Miocene-Quaternary, deep-water (>2 km emplacement depth) volcanoes buried beneath 55–330 m of sedimentary strata in the South China Sea. The volcanoes have crater-like bases, which truncate underlying strata and suggest extrusion was initially explosive, and erupted lava flows that feed lobate lava fans. The lava flows are >9 km long and contain lava tubes that have rugged basal contacts defined by ~90±23 m high erosional ramps. We suggest the lava flows eroded down into and were emplaced within wet, unconsolidated, near-seafloor sediments. Extrusion dynamics were likely controlled by low magma viscosities as a result of increased dissolved H2O due to high hydrostatic pressure, and soft, near-seabed sediments, which collectively are characteristic of deep-water environments. We calculate that long run-out lava flows account for 50–97% of the total erupted volume, with a surprisingly minor component (~3–50%) being preserved in the main volcanic edifice. Accurate estimates of erupted volumes therefore require knowledge of volcano and lava basal surface morphology. We conclude that 3D seismic reflection data is a powerful tool for constraining the geometry, volumes, and extrusion dynamics of ancient or active deep-water volcanoes and lava flows.
Britton B, Jackson C, Wade J, 2019, The reward and risk of social media for academics, Nature Reviews Chemistry, Vol: 3, Pages: 459-461, ISSN: 2397-3358
We are three academics who are active on social media. We explore the motivations for and benefits of engaging with social media, as well as its costs and risks. Overall, we believe this engagement to be a net benefit for us, our employers and for wider society.
Rotevatn A, Jackson CA-L, Tvedt ABM, et al., 2019, How do normal faults grow?, Journal of Structural Geology, Vol: 125, Pages: 174-184, ISSN: 0191-8141
Normal faults grow via synchronous increase in displacement and length (‘propagating fault model’, also known as the ‘isolated fault model’), or by rapid length establishment and subsequent displacement accrual (constant-length fault model). We here use time-series displacement (D) and length (L) data from natural and experimental faults to elucidate growth styles and D-L trajectories throughout fault life, and to assess the applicability of the two fault models. We show that the growth of most faults is characterized by two stages, with the first defined by fault lengthening (20–30% of fault lifespan) and the second by displacement accrual (70–80% of fault lifespan). Although broadly adhering to the constant-length model, fault growth throughout the lengthening stage, during which significant displacement (10–60% of the total end-of-life fault displacement) may also accumulate, is achieved through rapid tip propagation, relay breaching, and segment linkage, characteristics perhaps most intuitively thought to reflect growth in accordance with the propagating model. The subsequent growth stage is dominated by displacement accrual with limited lateral tip propagation, a phenomenon best described by the constant-length model. We also show that, despite being used primarily in support of the propagating model, global displacement-length (D-L) datasets are equally compatible with the constant-length model.
Collanega L, Siuda K, Jackson CA-L, et al., 2019, Normal fault growth influenced by basement fabrics: The importance of preferential nucleation from pre-existing structures, BASIN RESEARCH, Vol: 31, Pages: 659-687, ISSN: 0950-091X
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- Citations: 37
Evans S, Jackson C, 2019, Base-Salt Relief Controls Salt-Related Deformation in the Outer Kwanza Basin, offshore Angola
Magee C, Muirhead J, Schofield N, et al., 2019, Structural signatures of igneous sheet intrusion propagation, Journal of Structural Geology, Vol: 125, Pages: 148-154, ISSN: 0191-8141
The geometry and distribution of planar igneous bodies (i.e. sheet intrusions), such as dykes, sills, and inclined sheets, has long been used to determine emplacement mechanics, define melt source locations, and reconstruct palaeostress conditions to shed light on various tectonic and magmatic processes. Since the 1970's we have recognised that sheet intrusions do not necessarily display a continuous, planar geometry, but commonly consist of segments. The morphology of these segments and their connectors is controlled by, and provide insights into, the behaviour of the host rock during emplacement. For example, tensile brittle fracturing leads to the formation of intrusive steps or bridge structures between adjacent segments. In contrast, brittle shear faulting, cataclastic and ductile flow processes, as well as heat-induced viscous flow or fluidization, promotes magma finger development. Textural indicators of magma flow (e.g., rock fabrics) reveal that segments are aligned parallel to the initial sheet propagation direction. Recognising and mapping segment long axes thus allows melt source location hypotheses, derived from sheet distribution and orientation, to be robustly tested. Despite the information that can be obtained from these structural signatures of sheet intrusion propagation, they are largely overlooked by the structural and volcanological communities. To highlight their utility, we briefly review the formation of sheet intrusion segments, discuss how they inform interpretations of magma emplacement, and outline future research directions.
Reeve M, Magee C, Bastow I, et al., 2019, Are magnetic stripes on the Cuvier Abyssal Plain (offshore NW Australia) diagnostic of oceanic crust?
Coleman AJ, Duffy OB, Jackson C, 2019, Growth folds above propagating normal faults, Earth-Science Reviews, ISSN: 1872-6828
Duffy OB, Fernandez N, Peel FJ, et al., 2019, Obstructed minibasins on a salt-detached slope: An example from above the Sigsbee canopy, northern Gulf of Mexico, BASIN RESEARCH, ISSN: 0950-091X
Evans S, Jackson CA, 2019, Intrasalt structure and strain partitioning in layered evaporites: Insights from the Messinian salt in the eastern Mediterranean
The deforming Messinian evaporite sequence is lithologically heterogeneous and structurally complex. Understanding the Messinian stratigraphy and its influence on the intrasalt strain distribution is essential for accurate velocity modelling and efficient drilling of petroleum prospects in the pre-salt domain. We use high quality 3D seismic reflection data from offshore Lebanon to show vertical and lateral variations in strain across the dataset.
Nugraha H, Jackson C, Johnson H, et al., 2019, Tectonic and oceanographic process interactions archived in the Late Cretaceous to Present deep-marine stratigraphy on the Exmouth Plateau, offshore NW Australia, Basin Research, Vol: 31, Pages: 405-430, ISSN: 0950-091X
Deep-marine deposits provide a valuable archive of process interactions between sediment gravity flows, pelagic sedimentation, and thermo-haline bottom-currents. Stratigraphic successions can also record plate-scale tectonic processes (e.g. continental breakup and shortening) that impact long-term ocean circulation patterns, including changes in climate and biodiversity. One such setting is the Exmouth Plateau, offshore NW Australia, which has been a relatively stable, fine-grained carbonate-dominated continental margin from the Late Cretaceous to Present. We combine extensive 2D (~40,000 km) and 3D (3,627 km2) seismic reflection data with lithologic and biostratigraphic information from wells to reconstruct the tectonic and oceanographic evolution of this margin. We identified three large-scale seismic units (SUs): (1) SU-1 (Late Cretaceous) – 500 m-thick, and characterised by NE-SW-trending, slope-normal elongate depocentres (c. 200 km long and 70 km wide), with erosional surfaces at their bases and tops, which are interpreted as the result of contour-parallel bottom-currents, coeval with the onset of opening of the Southern Ocean; (2) SU-2 (Palaeocene – Late Miocene) – 800 m-thick and characterised by: (i) very large (amplitude, c. 40 m and wavelength, c. 3 km), SW-migrating, NW-SE-trending sediment waves, (ii) large (4 km-wide, 100 m-deep), NE-trending scours that flank the sediment waves, and (iii) NW-trending, 4 km wide and 80 m deep turbidite channel, infilled by NE-dipping reflectors, which together may reflect an intensification of NE-flowing bottom currents during a relative sea-level fall following the establishment of circumpolar-ocean current around Antarctica; and (3) SU-3 (Late Miocene – Present) – 1000 m-thick and is dominated by large (up to 100 km3) mass-transport complexes (MTCs) derived from the continental margin (to the east) and the Exmouth Plateau Arch (to the west), and accumulated mainly in the adjacent Kangaro
Steventon M, Jackson C, Hodgson D, et al., 2019, Strain analysis of a seismically-imaged mass-transport complex (MTC), offshore Uruguay, Basin Research, Vol: 31, Pages: 600-620, ISSN: 0950-091X
Strain style, magnitude, and distribution within mass-transport complexes (MTCs) is important for understanding the process evolution of submarine mass flows and for estimating their runout distances. Structural restoration and quantification of strain in gravitationally-driven passive margins have been shown to approximately balance between updip extensional and downdip compressional domains; such an exercise has not yet been attempted for MTCs. We here interpret and structurally restore a shallowly buried (c. 1500 mbsf) and well-imaged MTC, offshore Uruguay using a high-resolution (12.5 m vertical and 15x12.5 m horizontal resolution) 3D seismic-reflection survey. This allows us to characterise and quantify vertical and lateral strain distribution within the deposit. Detailed seismic mapping and attribute analysis shows that the MTC is characterised by a complicated array of kinematic indicators, which vary spatially in style and concentration. Seismic-attribute extractions reveal several previously undocumented fabrics preserved in the MTC, including internal shearing in the form of sub-orthogonal shear zones, and fold-thrust systems within the basal shear zone beneath rafted-blocks. These features suggest multiple phases of flow and transport directions during emplacement. The MTC is characterised by a broadly tripartite strain distribution, with extensional (e.g. normal faults), translational and compressional (e.g. folds and thrusts) domains, along with a radial frontally emergent zone. We also show how strain is preferentially concentrated around intra-MTC rafted-blocks due to kinematic interaction between these features and the underlying basal shear zone. Overall, and even when volume loss within the frontally emergent zone is included, a strain deficit between the extensional and compressional domains (c. 3-14%) is calculated, which we attribute to a combination of distributed, sub-seismic, ‘cryptic’ strain, likely related to de-watering, grain-
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