Imperial College London

Professor Christopher Jackson

Faculty of EngineeringDepartment of Earth Science & Engineering

Visiting Professor
 
 
 
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Contact

 

c.jackson Website

 
 
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Location

 

1.46ARoyal School of MinesSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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400 results found

Dobb EM, Magee C, Jackson CA-L, Lathrop B, Köpping Jet al., 2024, Impact of igneous intrusion and associated ground deformation on the stratigraphic record, Geological Society, London, Special Publications, Vol: 525, ISSN: 0305-8719

<jats:title>Abstract</jats:title> <jats:p>The geomorphology and sediment systems of volcanic areas can be influenced by uplift (forced folding) related to subsurface migration and accumulation of magma. Seismic geomorphological analysis presents a unique tool to study how surface morphology and subsurface magma dynamics relate, given seismic reflection data can image buried landscapes and underlying intrusions in 3D at resolutions of only a few metres–decametres. However, differential compaction of the sedimentary sequence above incompressible igneous intrusions during burial modifies palaeosurface morphology. Here we use 3D seismic reflection data from offshore NW Australia to explore how the stratigraphic record of igneous intrusion and associated ground deformation can be unravelled. We focus on a forced fold that likely formed in the Early Cretaceous to accommodate intrusion of magma, but which was later amplified by burial-related differential compaction of the host sedimentary sequence. We show how: (1) marine channels and clinoforms may be deflected by syn-depositional intrusion-induced forced folds; and (2) differential compaction can locally change clinoforms depth post-deposition, potentially leading to erroneous interpretation of shoreline trajectories. Our results demonstrate seismic geomorphological analysis can help us better understand how magma emplacement translates into ground deformation, and how this shapes the landform of volcanic regions.</jats:p>

Journal article

Martinez C, Chiarella D, Jackson CAL, Rennie H, Scarselli Net al., 2024, Syn-rift tectono-stratigraphic development of the Thebe-0 fault system, Exmouth Plateau, offshore NW Australia: The role of fault-scarp degradation, Basin Research, Vol: 36, ISSN: 0950-091X

The syn-rift architecture of extensional basins records deposition from and interactions between footwall-, hangingwall-, and axially-derived systems. However, the exact controls on their relative contributions and the overall variable depositional architecture, and how their sediment volume varies through time, remains understudied. We undertook a quantitative approach to determine temporal and spatial changes in the contribution of fault-scarp degradation to the syn-rift tectono-stratigraphic development of the Thebe-0 fault system on the Exmouth Plateau (NW Shelf, offshore Australia), using high-quality 3D seismic reflection and boreholes data. The magnitude of footwall erosion was measured in terms of vertical (VE) and headward (HE) erosion by calculating the volume of eroded material along the footwall scarp. A detailed seismic-stratigraphic and facies analysis allowed us to constrain the architectural variability of the hangingwall depositional systems and the types of resulting deposits (i.e., fault-controlled base-of-scarp, settling from suspension, and hangingwall-derived). After addressing the syn-rift tectono-stratigraphic framework, we suggest that periods of significant erosion along the Thebe-0 fault scarp are related to the accumulation of fault-controlled base-of-scarp deposits characterised by comprising a lower wedge with chaotic to low-continuity reflections. Footwall-derived deposits characterised by an upward decrease in stratigraphic dip are interpreted as related to periods of reduced fault activity and sustained sediment delivery sourced from the footwall scarp and systems beyond it (e.g., antecedent systems). We then analysed the tectono-stratigraphic framework and the volumetric comparison between material eroded from the fault-scarp and accumulated in the basin, aiming to estimate the contribution of fault-scarp degradation to the hangingwall syn-rift fill. Our results suggest periods of enhanced fault activity control fault-scarp degradat

Journal article

Wrona T, Pan I, Bell RE, Jackson CAL, Gawthorpe RL, Fossen H, Osagiede EE, Brune Set al., 2023, Complex fault system revealed by 3-D seismic reflection data with deep learning and fault network analysis, Solid Earth, Vol: 14, Pages: 1181-1195, ISSN: 1869-9510

Understanding where normal faults are located is critical for an accurate assessment of seismic hazard; the successful exploration for, and production of, natural (including low-carbon) resources; and the safe subsurface storage of CO2. Our current knowledge of normal fault systems is largely derived from seismic reflection data imaging, intracontinental rifts and continental margins. However, exploitation of these data sets is limited by interpretation biases, data coverage and resolution, restricting our understanding of fault systems. Applying supervised deep learning to one of the largest offshore 3-D seismic reflection data sets from the northern North Sea allows us to image the complexity of the rift-related fault system. The derived fault score volume allows us to extract almost 8000 individual normal faults of different geometries, which together form an intricate network characterised by a multitude of splays, junctions and intersections. Combining tools from deep learning, computer vision and network analysis allows us to map and analyse the fault system in great detail and in a fraction of the time required by conventional seismic interpretation methods. As such, this study shows how we can efficiently identify and analyse fault systems in increasingly large 3-D seismic data sets.

Journal article

Fernandez N, Duffy O, Jackson C, Kaus B, Dooley T, Hudec Met al., 2023, How Fast Can Minibasins Translate Down a Slope? Observations from 2D Numerical Models, Tektonika, Vol: 1, ISSN: 2976-548X

<jats:p>Minibasins are important features in salt-bearing basins and are abundant in salt-detached continental slopes where the salt and the overlying sedimentary cover (including minibasins) undergo seaward translation due to gravity. One question which is relevant for understanding the structural evolution of salt-detached slopes is what controls the translation velocity of the salt layer and of overlying minibasins. The aim of this study is three-fold: 1) to compare minibasin downslope translation velocity with salt translation velocity; 2) to understand what controls minibasin translation velocity and 3) to understand how minibasins translating at different velocities can kinematically interact and modify strain patterns around them. To address these questions, we present a 2D numerical modelling study. In addition to parameters that control salt velocity, we show that minibasin thickness is the main factor controlling minibasin velocity in the numerical models. If the minibasin is far from the base-of-salt, its velocity can be estimated by a 1D analytical solution of salt flowing on a slope. Specifically, thicker minibasins translate slower than thinner minibasins. If the minibasin is close to the base-of-salt, viscous drag slows it further, and the numerical results deviate from the 1D analytical solution. Finally, we assess how several minibasins of differing thicknesses and translation velocities, may diverge or converge as they translate downslope, resulting in varying strain patterns around them. Findings from our numerical modelling provide additional conceptual understanding of structural evolution of salt-detached continental slopes that have significant implications for understanding minibasin behaviour, and interpreting strain patterns around them.</jats:p>

Journal article

Nakken L, Chiarella D, Jackson CA-L, 2023, Late Jurassic rift physiography of the Froan Basin and Froya High, offshore Mid-Norway: Development of a syn-rift shallow marine system, BASIN RESEARCH, Vol: 35, Pages: 1908-1932, ISSN: 0950-091X

Journal article

Amarante F, Kuchle J, Jackson C, Scherer C, Pichel Let al., 2023, The cryptic stratigraphic record of the syn- to post-rift transition in the offshore Campos Basin, SE Brazil

<jats:p>Rift basins typically comprise three main tectono-stratigraphic stages; pre-, syn-, and post-rift. The syn-rift stage is often characterised by the deposition of asymmetric wedges of growth strata that record differential subsidence caused by active normal faulting. The subsequent post-rift stage is defined by long-wavelength subsidence driven by lithospheric cooling, and is typified by the deposition of broadly tabular stratal packages that drape any rift-related relief. The stratigraphic contact between syn- and post-rift rocks is often thought to be represented by an erosional unconformity. However, the late syn-rift to early post-rift stratigraphic record is commonly far more complex since: (i) the associated tectonic transition is not instantaneous; (ii) net-subsidence may be punctuated by transient periods of uplift; and (iii) strain often migrates oceanward during rifting until continental breakup is achieved with crustal rupture. The Eastern Brazilian marginal basins have not historically used the tripartite scheme outlined above, with the post-pre-rift interval instead being subdivided into rift, sag, and passive margin tectono-stratigraphic stages. The sag stage has been previously described as late syn-rift, early post-rift, or as a transition between the two, with the passive margin stage being equivalent to the classically defined post-rift, drift stage. Two (rather than one) erosional unconformities are also identified within the rift-to-sag succession. In this work, we use 2D and 3D seismic reflection and borehole data to discuss the expression of and controls on the syn- to post-rift transition in the shallow and deep water domains of the south-central Campos Basin, southeast Brazil. We identified three seismic-stratigraphic sequences bounded by unconformities. The lower pre-salt interval is characterised by wedge-shaped packages of reflections that thicken towards graben and half-graben-bounding normal faults. This stage ends with a de

Journal article

do Amarante FB, Kuchle J, Jackson CA-L, Scherer CMDS, Pichel LMet al., 2023, The cryptic stratigraphic record of the syn- to post-rift transition in the offshore Campos Basin, SE Brazil, BASIN RESEARCH, ISSN: 0950-091X

Journal article

Martinez-Donate A, Kane IAA, Hodgson DMM, Privat AMLJ, Jackson CAL, Schwarz E, Flint SSSet al., 2023, Stratigraphic change in flow transformation processes recorded in early post-rift deep-marine intraslope lobe complexes, SEDIMENTOLOGY, Vol: 70, Pages: 1379-1412, ISSN: 0037-0746

Journal article

Osagiede EE, Nixon CW, Gawthorpe R, Rotevatn A, Fossen H, Jackson CA-L, Tillmans Fet al., 2023, Topological Characterization of a Fault Network Along the Northern North Sea Rift Margin, TECTONICS, Vol: 42, ISSN: 0278-7407

Journal article

Alghuraybi A, Bell R, Jackson C, 2023, A snapshot of the earliest stages of normal fault growth, Tektonika, Vol: 1, Pages: 11-31, ISSN: 2976-548X

Observations of how faults lengthen and accrue displacement during the very earliest stages of their growth are limited, reflecting the fact that the early syn-kinematic sediments that record this growth are often deeply buried and difficult to image with geophysical data. Here, we use borehole and high-quality 3D seismic reflection data from SW Barents Sea, offshore Norway to quantify the lateral propagation (c. 0.38 – 3.4 mm/year) and displacement accumulation (c. 0.0062 – 0.025 mm/year) rates (averaged over 6.2 Myr) for several long (up to 43 km), moderate displacement (up to 155 m), syn-kinematic faults that we argue provide a unique, essentially ‘fossilised’ snapshot of the earliest stage of fault growth. We show that lateral propagation rates were up to 300 times faster than displacement rates during the initial ~25% of fault lifespan, suggesting that these faults lengthened much more rapidly than they accrued displacement. Our inference of rapid lengthening is also supported by geometric observations including: (i) low Dmax/Lmax (<0.01) scaling relationships, ii) high (>5) length/height aspect ratios, iii) broad, bell-shaped throw-length profiles, and iv) hangingwall depocenters forming during deposition of the first seismically detectable stratigraphic unit spanning the length of the fault. We suggest that the high ratio between lateral propagation rate and displacement rate is likely due to relative immaturity of the studied fault system, an interpretation that supports the ‘constant-length’ fault growth model. Our results highlight the need to document both displacement and lateral propagation rates to further our understanding of how faults evolve across various temporal and spatial scales.

Journal article

Oppo D, Jackson CA-L, Gorini C, Iacopini D, Evans S, Maselli Vet al., 2023, Mass wasting records the first stages of the Messinian Salinity Crisis in the eastern Mediterranean, GEOLOGY, Vol: 51, Pages: 637-641, ISSN: 0091-7613

Journal article

Erdi A, Jackson CA-L, Soto JI, 2023, Extensional deformation of a shale-dominated delta: Tarakan Basin, offshore Indonesia, BASIN RESEARCH, Vol: 35, Pages: 1071-1101, ISSN: 0950-091X

Journal article

Andrews B, Mildon Z, Jackson C, 2023, The impact of human factors and measurement obliquity when extracting geological slip-rate from seismically imaged normal faults.

<jats:p>Seismic reflection datasets can help unpick the long term (i.e., 100 kyr to Ma) slip history of active normal faults (e.g., Nicol et al., 2005). To constrain slip-rate from seismically imaged normal faults you measure the across-fault offset of stratigraphic markers of known age. &amp;#160;Ideally, this is undertaken parallel to the slip-vector, i.e., orthogonal to fault-strike. In many active systems this is not possible with only non-optimally orientated 2D surveys available. Here we assess how obliquity effects continuous and discontinuous fault properties (throw, heave, dip, displacement) extracted from normal faults imaged in a 3D seismic cube. We targeted &amp;#8216;straight&amp;#8217; faults and extracted cut off data from sequentially oblique sample lines ranging from &amp;#177;50&amp;#730;, comparing oblique data to that extracted from optimally orientated lines. Additionally, repeat picks were undertaken on two horizons to investigate the relative importance of measurement obliquity and human error.Oblique measurements showed different along-fault profiles compared to orientated sample lines. This causes some datasets to be statistically different, with &gt;100 % difference occasionally observed. Continuous deformation is more prone to obliquity errors, with the measurement of an apparent dip causing heave, and therefore displacement and dip, to display large differences at high obliquity. The dip of horizons close to the fault and localised complexity at the sample location (e.g., nearby faults) are also important factors. Differences regularly exceed 20% at high obliquity and we therefore suggest obliquity should not exceed 15&amp;#730; and were this is not possible measurements are corrected using fault cut offs and local fault strike.For repeats picks, the shape of along-fault profiles is similar; however, subtle differences exist. Variability depends on the fault and fault parameter, with greater differences o

Other

do Amarante FB, Jackson CA-L, Pichel LM, 2023, Post-salt magmatism in the Campos Basin, offshore SE Brazil: style, distribution, and relationship to salt tectonics, JOURNAL OF SOUTH AMERICAN EARTH SCIENCES, Vol: 125, ISSN: 0895-9811

Journal article

Wrona T, Whittaker AC, Bell RE, Gawthorpe RL, Fossen H, Jackson CA-L, Bauck MSet al., 2023, Rift kinematics preserved in deep-time erosional landscape below the northern North Sea, Basin Research, Vol: 35, Pages: 744-761, ISSN: 0950-091X

Our understanding of continental rifting is, in large parts, derived from the stratigraphic record. This record is, however, incomplete as it does not often capture the geomorphic and erosional signal of rifting. New 3D seismic reflection data reveal a Late Permian-Early Triassic landscape incised into the pre-rift basement of the northern North Sea. This landscape, which covers at least 542 km2, preserves a drainage system bound by two major tectonic faults. A quantitative geomorphic analysis of the drainage system reveals 68 catchments, with channel steepness and knickpoint analysis of catchment-hosted palaeo-rivers showing that the landscape preserved a >2 Myr long period of transient tectonics. We interpret that this landscape records a punctuated uplift of the footwall of a major rift-related normal fault (Vette Fault) at the onset of rifting. The landscape was preserved by a combination of relatively rapid subsidence in the hangingwall of a younger fault (Øygarden Fault) and burial by post-incision sediments. As such, we show how and why erosional landscapes are preserved in the stratigraphic record, and how they can help us understand the tectono-stratigraphic evolution of ancient continental rifts.

Journal article

Joffe A, Jackson CA-L, Steinberg J, Bell RE, Makovsky Yet al., 2023, Origin and kinematics of a basin-scale, non-polygonal, layer-bound normal fault system in the Levant Basin, eastern Mediterranean, Basin Research, Vol: 35, Pages: 662-691, ISSN: 0950-091X

Polygonal, layer-bound normal faults can extend over very large areas (>2,000,000 km2) of sedimentary basins. Best developed in very fine-grained rocks, these faults are thought to form during early burial in response to a range of diagenetic processes, including compaction and water expulsion. Local deviations from this idealised polygonal pattern are common; however, basin-scale, layer-bound faults with non-polygonal map view are not well-documented and accordingly, their genesis is not well understood. In this study, we use 3D seismic reflection data, biostratigraphy and well logs from the Southern Levant Basin, offshore Israel, to develop an age-constrained seismic-stratigraphic framework and determine the geometry and kinematics of such basin-scale fault system. The faults tip out downwards along an Eocene Unconformity, but unlike layer-bound faults in the Northern Levant Basin, they do not reach the base of the Messinian evaporites, instead tipping out upwards at the top Langhian. On average, the faults in the Southern Levant Basin are 6.3 km long, have an average throw of 120 m, and consistently strike NW-SE. Throw-depth plots, accompanied by thickness changes, indicate that the faults accumulated growth strata during the Late Burdigalian and are spatially and kinematically associated with a WSW-ESE-striking strike-slip fault. Unlike true polygonal faults, these faults propagated through ca. 2 km-thick sandstone-prone Oligocene-Miocene strata. Whereas previous studies from the Northern Levant Basin associate fault nucleation and growth with burial-related diagenesis, the sandstone-prone character of the Oligocene-Miocene suggests that this process cannot be readily applied to the Southern Levant Basin. Instead, we highlight potential tectonic events that occurred during and may have triggered thin-skinned extension at times of fault growth.

Journal article

Joffe A, Jackson CA-L, Pichel LMM, 2023, Syn-depositional halokinesis in the Zechstein Supergroup (Lopingian) controls Triassic minibasin genesis and location, BASIN RESEARCH, Vol: 35, Pages: 784-801, ISSN: 0950-091X

Journal article

Amarante F, Jackson C, Pichel L, 2023, Post-salt magmatism in the Campos Basin, offshore SE Brazil: style, distribution, and relationship to salt tectonics

<jats:p>Substantial magmatism occurred during the development of the marginal basins of the central and southern South Atlantic. Situated on the Brazilian side of the central segment, the Campos and Santos basin represent a transitional margin, located between the magma-rich margin in the north and the magma-poor margin in the south. In addition to magmatism associated with the initiation of continental rifting, the southeast Brazilian basins experienced three main magmatic events; one during the early post-rift (i.e., sag stage) and two during the late post-rift (i.e., passive margin stage), both occurring after deposition of a thick, late Aptian salt layer. The products of post-salt, intrusive and extrusive magmatism in the southern Campos Basin are imaged in seismic reflection data and have been directly penetrated by boreholes, yet they remain poorly understood in terms of their style, detailed geometry, and distribution. Furthermore, the temporal, spatial and possibly genetic relationships between these post-salt igneous products and salt-tectonics are largely unknown. Documenting these possible salt-magma interactions is important to understanding the tectono-stratigraphic evolution of Campos Basin and other salt-bearing passive margin basins subject to magmatic activity. We use 2D and 3D seismic reflection and borehole data from the southeastern Campos Basin, offshore Brazil to map and characterize post-salt igneous sills and volcanoes, and to understand the interaction between salt tectonics and igneous products. We identified 99 sills emplaced within uppermost Aptian-to-Maastrichtian strata, 83 emplaced above the salt and 16 intra-salt, and 15 volcanoes within Upper Cretaceous-to-lower Paleogene strata, associated with a &gt;310 km² lava field. We also identify four, subsalt-sourced, vent-like structures, which vary in age from Paleogene to Late Cretaceous. Salt and overburden structures define a domain of extensional deformation on a base-sa

Journal article

Dowey N, Giles S, Jackson C, Williams R, Fernando B, Lawrence A, Raji M, Barclay J, Brotherson L, Childs E, Houghton J, Khatwa A, Mills K, Newton A, Rockey F, Rogers S, Souch Cet al., 2023, The Equator Project

<jats:p>Geography, Earth and Environmental Science (GEES) research will play a vital role in addressing the grand challenges of the 21st century, contributing to many of the UN sustainable development goals and the global energy transition. However, geoscience knowledge cannot be successfully applied to global problems that impact people from all walks of life unless the discipline itself is equitable. There is a well-documented racial and ethnic diversity crisis in GEES subjects in the Global North1 that leads to inequities in who does environmental research. The Equator project set out to increase participation and retention of UK-domiciled Black, Asian and minority ethnic postgraduate research (PGR) students in GEES topics. Our goal was to improve equity and diversity in a research area critical to a more sustainable future; not because of a business case, or for diversity as resource- but for social justice.Equator was a six-month project, funded by the Natural Environment Research Council (NERC), that developed three evidence-based interventions targeting different barriers to racial and ethnic diversity in GEES research. To remove barriers to access, a doctoral training working group was formed to share best practice and develop recommendations to make PhD recruitment more equitable. To improve access and participation, a ring-fenced research school for ethnic minority undergraduate, masters and doctoral students was delivered. To increase retention and improve student experience, a targeted mentoring network pairing students with mentors from both industry and academia was created.Evaluation of interventions took the form of action research with a Theory of Change approach, with surveys used to capture thoughts and reflections in each of the three work packages. This occurred alongside collaborative, self-reflective inquiry within the project team and steering committee. The steering committee included grassroots organisations, higher education institut

Journal article

Zhang Y, Jackson C, Darraj N, Krevor Set al., 2023, Carbon dioxide storage resource use trajectories consistent with US climate change mitigation scenarios

<jats:p>To progress decarbonisation in the United States, numerous techno-economic models have been built projecting climate change mitigation scenarios that include CO2 storage deployment at annual injection rates of 0.3 – 1.7 Gt yr-1 by 2050. However, these projections do not include geological, technical, or socio-economic factors that could impede the growth of geological storage resource use. Here, we apply a growth modelling framework to evaluate CO2 storage scenarios proposed in the Net Zero America, Carbon Neutral Pathways, Long-Term Strategy, and Decarb America reports. Our modelling framework uses logistic curves to analyse the feasibility of growth trajectories under constraints imposed by the associated storage resource availability. We show that the entire storage demand for the US can be accommodated by the resources available in the Gulf Coast alone. Deployment trajectories require sustained average annual (exponential) growth at rates &gt;10% nationally and between 3% - 20% regionally across four storage hubs. These scale-up rates are high relative to those characterising analogous, historical, large-scale energy infrastructure projects in the US (4%), suggesting that modelled projections in current reports are too aggressive in their deployment of CCS. These models could be easily constrained to more realistic deployment trajectories with the type of modelling framework we present here.</jats:p>

Journal article

Magee C, Reeve MT, Jackson CA-L, Bell RE, Bastow IDet al., 2023, Reply to Alves et al. (2022) discussion on "Stratigraphic record of continental breakup, offshore NW Australia" by Reeve et al. (2022), Basin Research, Vol: 35, Pages: 483-486, ISSN: 0950-091X

Journal article

Erdi A, Jackson C, Soto J, 2023, Extensional Deformation of a Shale-dominated Delta: Tarakan Basin, Offshore Indonesia

<jats:p>Deformation on shale-rich continental margins is commonly associated with thin-skinned extension above mobile shales. Normal faulting and shale mobilization are widespread on such margins, being associated with and controlled by progradation and gravitational failure of deltaic sedimentary wedges. However, due to limitations in our ability to seismically imaging these mobile shales, our understanding of how base-shale relief controls deformation, and the shape, size, and distribution of shale structures remain poorly understood. We here use 3D seismic reflection data from the Tarakan Basin, offshore Indonesia to investigate the temporal and spatial evolution of thin-skinned deformations of the Neogene sedimentary section. Our detailed seismic interpretation reveals long (≤ 74 km), concave- and convex-into-the-basin faults, dipping both basinward (eastwards) and locally landward (westwards), which detach downwards on a basal mobile shale (Middle Miocene). The base of the shale unit dips gently (&lt; 17o) seaward, although older (Paleogene), rift-related normal faults mean a local base-shale relief is present. Our analysis of isochron (thickness map) analysis shows that supra-shale normal faulting commenced in the Middle Miocene and was accompanied by the formation of hanging wall rollover folds and associated crestal grabens, with the subsequent along- and across strike migration of strain being related to the nucleation, lateral linkage, and reactivation of individual fault systems. Updip growth faulting was also accompanied by the downslope flow of mobile shale, margin-parallel and-perpendicular differential loading, and local contraction and mobile shale-upbuilding, resulting in the growth of large, margin-parallel shale anticlines further downdip. These faults and anticlines are locally overlain by tall (≤ 5 km) mud diapirs and volcanoes. We suggest that variations in the rate of sediment loading, mobile shale flow, fault growth, and gravi

Journal article

Wu N, Jackson CAL, Clare MA, Hodgson DM, Nugraha HD, Steventon MJ, Zhong G, Wu N, Jackson CAL, Clare MA, Hodgson DM, Nugraha HD, Steventon MJ, Zhong Get al., 2023, Diagenetic priming of submarine landslides in ooze-rich substrates, GEOLOGY, Vol: 51, Pages: 85-90, ISSN: 0091-7613

Journal article

Pichel LM, Ferrer O, Jackson CA-L, Roca Eet al., 2022, Physical modelling of the interplay between salt-detached gravity gliding and spreading across complex rift topography, Santos Basin, offshore Brazil, BASIN RESEARCH, Vol: 34, Pages: 2042-2063, ISSN: 0950-091X

Journal article

Jackson C, Evans S, Alshammasi T, 2022, Salt welding during canopy advance and shortening in the Green Canyon Area, northern Gulf of Mexico

<jats:p>Welds form due to tectonically-induced thinning and/or dissolution of salt, with their composition and completeness thought to at least partly reflect their structural position within the salt-tectonic system. Despite their importance as seals or migration pathways for accumulations of hydrocarbons and CO2, we have relatively few published examples of drilled subsurface welds; such examples would allow us to improve our understanding of the processes and products of welding, and to test analytical models of the underlying mechanics. In this study we integrate 3D seismic reflection and borehole data from the Green Canyon Area of the northern Gulf of Mexico, USA to characterize the geophysical and geological expression of a tertiary weld, as well as its broader salt-tectonic context. These data show although it appears complete on seismic reflection data, the weld contains 124 ft (c. 38 m) of pure halite. This thickness is consistent with the predictions of analytical models, and with observations from other natural examples of subsurface welds. Our observations also support a model whereby compositional fractionation of salt occurs as the salt-tectonic system evolves; in this model, less mobile and/or denser units, if originally present, are typically stranded within the deeper, autochthonous level, trapped in primary welds, or near the basal root of diapirs, whereas less viscous and/or less dense units form the cores of these diapirs and, potentially, genetically related allochthonous sheets and canopies. We also show that shearing of the weld during downslope translation of the overlying minibasin did not lead to complete welding.</jats:p>

Journal article

Joffe A, Jackson C, Pichel L, 2022, Syn-Depositional Halokinesis in the Zechstein Supergroup (Lopingian) Controls Triassic Minibasin Genesis and Location

<jats:p>Salt tectonics is typically caused by the flow of mobile evaporites in response to post-depositional gravity gliding and/or differential loading by overburden sediments. This situation is considerably more complex near the margins of salt basins, where carbonate and clastic rocks may be deposited at the same time and interbedded with more mobile evaporitic strata. In these cases, syn-depositional salt flow may occur due to density differences in the deposited lithologies, although our understanding of this and related processes is relatively poor. We here use 3D seismic reflection and borehole data from the Devil’s Hole Horst, West Central Shelf, offshore UK to understand the genesis, geometry and kinematic evolution of intra-Zechstein Supergroup (Lopingian) minibasins and their effect on post-depositional salt deformation. We show that immobile, pinnacle-to-barrier-like, carbonate build-ups and anhydrite are largely restricted to intra-basin highs, whereas mobile halite, which flowed to form large diapirs, dominates in the deep basin. At the transition between the intra-basin highs and the deep basin, a belt of intra-Zechstein minibasins occur, forming due to the subsidence of relatively dense anhydrite into underlying halite. Depending on primary halite thickness, these intra-Zechstein minibasins created topographic lows, dictating the position for nucleation and subsequent down-building of Triassic minibasins. Our study refines the original depositional model for the Zechstein Supergroup in the Central North Sea, with the results also helping us better understand the style and distribution of syn-depositional salt flow on other layered evaporitic sequences and the role intra-salt heterogeneity and related deformation may have in the associated petroleum plays.</jats:p>

Journal article

Nugraha HD, Jackson CA-L, Johnson HD, Hodgson DM, Clare MAet al., 2022, Extreme erosion by submarine slides, GEOLOGY, Vol: 50, Pages: 1130-1134, ISSN: 0091-7613

Journal article

Wu N, Jackson C, Clare M, Hodgson D, Nugraha H, Steventon M, Zhong Fet al., 2022, Diagenetic priming of submarine landslides in ooze-rich substrates

<jats:p>Oozes are the most widespread deep-sea sediment in the global ocean, but very little is known about how changes in their physical properties during burial impact slope stability and related geohazards. Here, we use 3D seismic reflection, geochemical, and petrophysical data acquired both within and adjacent to 13 large (in total c. 6330 km2) submarine slides on the Exmouth Plateau, NW Shelf, Australia, to investigate how the pre-slide physical properties of oozes control slope failure and emplacement processes. Our integrated dataset allows potential slide surfaces to be detected within ooze successions; a crucial advance for improved submarine geohazard assessment. Moreover, we demonstrate that the interplay of tectonics, ocean current activity, and silica diagenesis can prime multiple slides on very low gradient slopes in tropical, oceanic basins. Therefore, the diagenetic state of silica-rich sediments must be considered to improve slope stability assessments.</jats:p>

Journal article

Erdi A, Jackson C, 2022, Salt-detached strike-slip faulting, Outer Kwanza Basin, Offshore Angola

<jats:p>We here use a 3D seismic reflection dataset from Outer Kwanza Basin, offshore Angola to examine the structure and growth of salt-detached strike-slip faults. The faults occur in four, up to 13.8 km-long, NE-trending arrays that are physically linked by restraining bend and releasing stepovers, and which presently overlie Aptian salt and base-salt relief related to pre-salt faulting. We suggest that these faults formed to accommodate along-margin variations in the rate and magnitude of differential seaward translation and salt diapirism, which commenced in the Early Cretaceous. We illustrate that the arrays grew by tip propagation of isolated fault segments, some of which linked during the Albian-Cenomanian (i.e., 113-100.5 Ma, or the initial 11-13% of their deformation history). Some arrays then reached their near-final length within the subsequent ca. 77 Ma, or the next 69-81% of their deformation history), while others attained this later, during the subsequent ca. 18 Ma (i.e., after 95% of their deformation history). During this time, the segments formed and then breached releasing and restraining stepovers, with the arrays as a whole growing by alternating periods of lengthening, throw accumulation, and inactivity. Our results also show that scatter in the D-L scaling of strike-slip faults reflect the propagation, interaction, and linkage of individual segments.</jats:p>

Journal article

Lathrop B, Bell R, Jackson C, Rotevatn A, Lathrop Bet al., 2022, Displacement/length scaling relationships for normal faults; a review, critique, and revised compilation, Frontiers in Earth Science, Vol: 10, ISSN: 2296-6463

The relationship between normal fault displacement (D) and length (L) varies due to numerous factors, including fault size, maturity, basin tectonic history, and host rock lithology. Understanding how fault D and L relate is useful, given related scaling laws are often used to help refine interpretations of often incomplete, subsurface datasets, which has implications for hydrocarbon and low-carbon energy applications. Here we provide a review of D/L scaling laws for normal faults, discuss factors that could influence these relationships, including both geological factors and errors in measurement, and provide a critique of previously published D/L databases. We then present our newly assembled database of 4059 normal faults from 66 sources that include explicit information on: 1) faultlength and displacement, 2) host rock lithology, 3) host basin tectonic history, and 4) maturity, as well as fault D and L through time when these data are available. We find an overall scaling law of D = 0.3L0.92, which is similar to previously published scaling equations and that varies in response to the aforementioned geological factors. Our data show thatsmall faults (<1 m length) tend to be over-displaced compared to larger faults, active faults tend to be over-displaced compared to inactive faults, and faults with stiffer host rock lithologies, like igneous and carbonate rocks, tend to be under-displaced with respect to faults within softer, more compliant host rocks, like clastic sedimentary rocks. Our dynamicD/L through time data show that faults follow the hybrid fault growth model, i.e., they initially lengthen, during which time they will appear under-displaced, before accumulating displacement. To the best of our knowledge, this is the first comprehensive, integrated, critical study of D/L scaling laws for normal faults and the factors influencing their growth. These revised relationships can now be utilized for predicting fault length or displacement when only one var

Journal article

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