Imperial College London

ProfessorHowardJohnson

Faculty of EngineeringDepartment of Earth Science & Engineering

Professor in Petroleum Geology
 
 
 
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Contact

 

+44 (0)20 7594 6450h.d.johnson

 
 
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Location

 

1.34Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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59 results found

Wu N, Jackson CA-L, Johnson HD, Hodgson DM, Nugraha HDet al., 2020, Mass-transport complexes (MTCs) document subsidence patterns in a northern Gulf of Mexico salt minibasin, BASIN RESEARCH, ISSN: 0950-091X

Journal article

Collins DS, Johnson HD, Baldwin CT, 2020, Architecture and preservation in the fluvial to marine transition zone of a mixed‐process humid‐tropical delta: Middle Miocene Lambir Formation, Baram Delta Province, north‐west Borneo, Sedimentology, Vol: 67, Pages: 1-46, ISSN: 0037-0746

The interaction of river and marine processes in the fluvial to marine transition zone fundamentally impacts delta plain morphology and sedimentary dynamics. This study aims to improve existing models of the facies distribution, stratigraphic architecture and preservation in the fluvial to marine transition zone of mixed‐process deltas, using a comprehensive sedimentological and stratigraphic dataset from the Middle Miocene Lambir Formation, Baram Delta Province, north‐west Borneo. Eleven facies associations are identified and interpreted to preserve the interaction of fluvial and marine processes in a mixed‐energy delta, where fluvial, wave and tidal processes display spatially and temporally variable interactions. Stratigraphic successions in axial areas associated with active distributary channels are sandstone‐rich, comprising fluvial‐and wave‐dominated units. Successions in lateral, or interdistributary, areas, which lack active distributary channels, are mudstone‐rich, comprising fluvial‐dominated, tide‐dominated and wave‐dominated units, including mangrove swamps. Widespread mudstone preservation in axial and lateral areas suggests well‐developed turbidity maximum zones, a consequence of high suspended‐sediment concentrations resulting from tropical weathering of a mudstone‐rich hinterland. Within the fluvial to marine transition zone of distributary channels, interpreted proximal–distal sedimentological and stratigraphic trends suggest: (i) a proximal fluvial‐dominated, tide‐influenced subzone; (ii) a distal fluvial‐dominated to wave‐dominated subzone; and (iii) a conspicuously absent tide‐dominated subzone. Lateral areas preserve a more diverse spectrum of facies and stratigraphic elements reflecting combined storm, tidal and subordinate river processes. During coupled storm and river floods, fluvial processes dominated the fluvial to marine transition zone along major and minor distributary channels and channel mouths, causing significant overprintin

Journal article

Levell BK, Johnson HD, Collins DS, Van Cappelle Met al., 2020, Deposition and preservation of fluvio-tidal shallow-marine sandstones: A re-evaluation of the Neoproterozoic Jura Quartzite (western Scotland), Sedimentology, Vol: 67, Pages: 173-206, ISSN: 0037-0746

The 2 to 5 km thick, sandstone‐dominated (>90%) Jura Quartzite is an extreme example of a mature Neoproterozoic sandstone, previously interpreted as a tide‐influenced shelf deposit and herein re‐interpreted within a fluvio‐tidal deltaic depositional model. Three issues are addressed: (i) evidence for the re‐interpretation from tidal shelf to tidal delta; (ii) reasons for vertical facies uniformity; and (iii) sand supply mechanisms to form thick tidal‐shelf sandstones. The predominant facies (compound cross‐bedded, coarse‐grained sandstones) represents the lower parts of metres to tens of metres high, transverse fluvio‐tidal bedforms with superimposed smaller bedforms. Ubiquitous erosional surfaces, some with granule–pebble lags, record erosion of the upper parts of those bedforms. There was selective preservation of the higher energy, topographically‐lower, parts of channel‐bar systems. Strongly asymmetrical, bimodal, palaeocurrents are interpreted as due to associated selective preservation of fluvially‐enhanced ebb tidal currents. Finer‐grained facies are scarce, due largely to suspended sediment bypass. They record deposition in lower‐energy environments, including channel mouth bars, between and down depositional‐dip of higher energy fluvio‐ebb tidal bars. The lack of wave‐formed sedimentary structures and low continuity of mudstone and sandstone interbeds, support deposition in a non‐shelf setting. Hence, a sand‐rich, fluvial–tidal, current‐dominated, largely sub‐tidal, delta setting is proposed. This new interpretation avoids the problem of transporting large amounts of coarse sand to a shelf. Facies uniformity and vertical stacking are likely due to sediment oversupply and bypass rather than balanced sediment supply and subsidence rates. However, facies evidence of relative sea level changes is difficult to recognise, which is attributed to: (i) the areally extensive and polygenetic nature of the preserved facies, and (ii) a large stored sedime

Journal article

Steventon M, Jackson C, Hodgson D, Johnson Het 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-

Journal article

Nugraha H, Jackson C, Johnson H, Hodgson D, Reeve Met 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

Journal article

Hamilton-Wright J, Dee S, von Nicolai C, Johnson Het al., 2019, Investigating controls on salt movement in extensional settingsusing finite-element modelling, Petroleum Geoscience, Vol: 25, Pages: 258-271, ISSN: 1354-0793

Salt structures present numerous challenges for targeting reservoirs. Salt movement within the subsurface can follow complex pathways, producing deformation patterns in surrounding strata which are often difficult to decipher. Consequently, the relative role of key salt-flow drivers and geological sensitivities on salt-structure evolution are often poorly understood. To address this, we have developed 2D geomechanical models using the finite-element method to simulate salt diapir and pillow development in two extensional tectonic settings. We conducted model sensitivity analyses to examine the influence of geological parameters on field-scale salt structures and their corresponding deformation pattern. Modelled diapirs developing in thin-skinned extensional settings closely resemble published analogue experiments; however, active and passive stages of diapir growth are seldom or never reached, respectively, thus challenging existing ideas that diapir evolution is dominated by passive growth. In all modelled cases, highly strained domains bound the diapir flanks where extensive small-scale faulting and fracturing can be expected. Asymmetrical diapirs are prone to flank collapse and are observed in models with fast extension or sedimentation rates, thin roof sections or salt layers, or initially short or triangular-shaped diapirs. In modelled thick-skinned extensional settings, salt pillows and suprasalt overburden faults can be laterally offset (decoupled) from a reactivating basement fault. This decoupling increases with increased salt-layer thickness, overburden thickness, sedimentation rate and fault angle, and decreased fault slip rates. Contrary to existing consensus, overburden grounding onto the basement fault scarp does not appear to halt development of salt structures above the footwall basement block.

Journal article

Collins D, Alvdis A, Allison P, Johnson H, Hill J, Piggott Met al., 2018, Controls on tidal sedimentation and preservation: insights from numerical tidal modelling in the late oligocene–miocene South China sea, Southeast Asia, Sedimentology, Vol: 65, Pages: 2468-2505, ISSN: 0037-0746

Numerical tidal modelling, when integrated with other geological datasets, can significantly inform the analysis of physical sedimentation processes and the depositional and preservational record of ancient tide-influenced shoreline–shelf systems. This is illustrated in the Oligo–Miocene of the South China Sea (SCS), which experienced significant changes in basin physiography and where tide-influenced, shoreline–shelf deposition is preserved in ca 10 sub-basins. Palaeogeographic reconstructions, palaeotidal modelling and regional sedimentary facies analysis have been integrated in order to evaluate the spatial–temporal evolution and physiographic controls on tidal sedimentation and preservation during the ca 25 Myr Oligo–Miocene record in the SCS. Palaeotidal modelling, using an astronomically forced and global tidal model (Fluidity) at a maximum 10 km resolution, indicates that spring tides along Late Oligocene–Middle Miocene coastlines were predominantly mesotidal– macrotidal and capable of transporting sand, which reflects two main conditions: (1) increased tidal inflow through wider ocean connections to the Pacific Ocean; and (2) tidal amplification resulting from constriction of the tidal wave in a ‘blind gulf’ type of basin morphology. Since the Middle–Late Miocene, a reduction in the amplitude and strength of tides in the SCS was mainly due to diminishing tidal inflow from the Pacific Ocean caused by the northward movement of the Philippines and Izu-Bonin-Mariana arc. Sensitivity tests to palaeogeographic and palaeobathymetric uncertainty indicate that regional–scale (100–1000s29 km) palaeogeographic changes influencing tidal inflow versus outflow can override local30scale (1–100s km) changes to tidal resonance and convergence effects (funnelling and shoaling), such as shelf width and shoreline geometry. Palaeotidal model results compare favourably to the distribution and sedimenta

Journal article

van Cappelle M, Hampson GJ, Johnson HD, 2018, Spatial and temporal evolution of coastal depositional systems and regional depositional process regimes: Campanian Western Interior Seaway, USA, Journal of Sedimentary Research, Vol: 88, Pages: 873-897, ISSN: 1527-1404

This paper provides a critical review and regional synthesis of Late Cretaceous shallow-marine deposits along part of the western margin of the Western Interior Seaway of North America, which contains the most extensively documented outcrop-based studies of siliciclastic coastal depositional systems in the world. The results of this synthesis are presented in the form of paleogeographic maps (covering present-day New Mexico, Utah, Colorado, and Wyoming, USA) for five timeslices in the Campanian. These maps are used to evaluate the spatial and temporal evolution of regional depositional process regimes along a large (> 1000 m) stretch of coastline. The evolution of regional depositional process regimes is linked to tectonic and paleoceanographic controls on the Western Interior Seaway, which enables the results of this synthesis to be applied to prediction of depositional process regimes in other, less intensively studied basins.Six gross depositional environments have been mapped for each timeslice: (1) alluvial to coastal-plain sandstones; (2) coastal-plain coals, mudstones, and sandstones; (3) shoreline sandstones; (4) marine mudstones; (5) gravity-flow siltstones and sandstones; and (6) marine marls and chalk. Shoreline sandstones in each timeslice are interpreted in further detail using documented evidence for the three principal classes of depositional process (wave, tidal, and fluvial) and published reconstructions of coastal morphology, which is widely considered to reflect depositional process regime. Based on these interpretations, shoreline sandstones are assigned to five categories of depositional process regime: (1) regressive wave-dominated shorefaces and delta fronts; (2) regressive river-dominated delta fronts; (3) regressive mixed tide- and wave-influenced delta fronts; (4) regressive tide-dominated delta fronts; and (5) transgressive barrier islands, back-barrier lagoons, and estuaries. The accuracy of and uncertainty in classification of deposit

Journal article

Collins DS, Johnson HD, Allison PA, Damit ARet al., 2018, Mixed process, humid-tropical, shoreline-shelf deposition and preservation: middle Miocene-modern Baram Delta Province, Northwest Borneo, Journal of Sedimentary Research, Vol: 88, Pages: 399-430, ISSN: 1527-1404

This evaluation of the Miocene–Modern Baram Delta Province (BDP) depositional system provides: (1) a rare case study of outcrop observations that can be directly compared with a closely comparable and geographically adjacent modern analogue; (2) new insights into how deposition and preservation occur across a range of process regimes in a highly aggradational tectono-stratigraphic setting; and (3) an example of a well-exposed mixed-influenced shoreline–shelf depositional system, displaying variable interaction of fluvial, wave, and tidal processes. The exceptionally close relationship between the present-day BDP source-to-sink system and its ancient (Miocene–Pliocene) counterpart is because the climatic (humid-tropical, ever-wet, monsoon-influenced), tectonic (active foreland margin), hydrological (multiple, relatively short rivers), and gross depositional (shoreline–shelf) settings have remained consistent over the past c. 15–20 Myr. This study compares exposure-based analyses of facies and stratigraphic architecture in the middle Miocene Belait Formation (eastern BDP) with process-based geomorphological and sedimentological analyses of coastal–deltaic depositional environments in the present-day BDP. The Belait Formation comprises three distinct types of vertical facies-succession sets: (1) aggradationally-stacked, upward-sanding units (10–50 m thick), dominated by erosionally based sandstone beds showing swaly cross-stratification and gutter casts, record deposition during simultaneously high storm-wave energy and storm-enhanced fluvial discharge (“storm floods”); these are interpreted as analogs for deposits along the present-day open coastline in the BDP (e.g., the present-day, open-shelf Baram delta and flanking strandplain); (2) aggradationally stacked, heterolithic, upward-sanding units characterized by interbedded swaly cross-stratified sandstone and combined-flow-rippled heterolithics, record deposition

Journal article

Collins DS, Avdis A, Allison PA, Johnson HD, Hill J, Piggott MD, Amir Hassan M, Damit ARet al., 2017, Tidal dynamics and mangrove carbon sequestration during the Oligo–Miocene in the South China Sea, Nature Communications, Vol: 8, ISSN: 2041-1723

Modern mangroves are among the most carbon-rich biomes on Earth, but their long-term (≥106 yr) impact on the global carbon cycle is unknown. The extent, productivity and preservation of mangroves are controlled by the interplay of tectonics, global sea level and sedimentation, including tide, wave and fluvial processes. The impact of these processes on mangrove-bearing successions in the Oligo–Miocene of the South China Sea (SCS) is evaluated herein. Palaeogeographic reconstructions, palaeotidal modelling, and facies analysis suggest that elevated tidal range and bed shear stress optimised mangrove development along tide-influenced tropical coastlines. Preservation of mangrove organic carbon (OC) was promoted by high tectonic subsidence and fluvial sediment supply. Lithospheric storage of OC in peripheral SCS basins potentially exceeded 4000 Gt (equivalent to 2000 ppm of atmospheric CO2). These results highlight the crucial impact of tectonic and oceanographic processes on mangrove OC sequestration within the global carbon cycle on geological timescales.

Journal article

Collins D, Johnson HD, Allison PA, Guilpain P, Razak Damit Aet al., 2017, Coupled ‘storm-flood’ depositional model: Application to the Miocene–Modern Baram Delta Province, north-west Borneo, Sedimentology, Vol: 64, Pages: 1203-1235, ISSN: 1365-3091

The Miocene to Modern Baram Delta Province is a highly efficient source to sink system that has accumulated 9 to 12 km of coastal-deltaic to shelf sediments over the past 15 Myr. Facies analysis based on ca 1 km of total vertical outcrop stratigraphy, combined with subsurface geology and sedimentary processes in the present-day Baram Delta Province, suggests a ‘storm-flood’ depositional model comprising two distinct periods: (i) fair-weather periods are dominated by alongshore sediment reworking and coastal sand accumulation; and (ii) monsoon-driven storm periods are characterised by increased wave energy and offshore-directed downwelling storm flow that occur simultaneously with peak fluvial discharge caused by storm-precipitation (‘storm-floods’). The modern equivalent environment has the following characteristics: (i) humid-tropical monsoonal climate; (ii) narrow (ca <100 km) and steep (ca 1°), densely vegetated, coastal plain; (iii) deep tropical weathering of a mudstone-dominated hinterland; (iv) multiple independent, small to moderate-sized (102 to 105 km2) drainage basins; (v) predominance of river-mouth bypassing; and (vi) supply-dominated shelf. The ancient, proximal part of this system (the onshore Belait Formation) is dominated by strongly cyclical sandier-upward successions (metre to decametre-scale) comprising (from bottom to top): (i) finely laminated mudstone with millimetre-scale silty laminae; (ii) heterolithic sandstone-mudstone alternations (centimetre to metre-scale); and (iii) sharp-based, swaley cross-stratified sandstone beds and bedsets (metre to decimetre-scale). Gutter casts (decimetre to metre-scale) are widespread, they are filled with swaley cross-stratified sandstone and their long-axes are oriented perpendicular to the palaeo-shoreline. The gutter casts and other associated waning-flow event beds suggest that erosion and deposition was controlled by high-energy, offshore-directed, oscillatory-dominated, s

Journal article

Alqahtani F, Jackson CA-L, Johnson HD, Som RBet al., 2017, Controls on The Geometry And Evolution of Humid-Tropical Fluvial Systems: Insights From 3D Seismic Geomorphological Analysis of The Malay Basin, Sunda Shelf, South-East Asia, Journal of Sedimentary Research, Vol: 87, Pages: 17-40, ISSN: 1527-1404

High-resolution three-dimensional (3D) seismic reflection data from the Pleistocene-to-Recent succession of the Malay Basin (Sunda Shelf, SE Asia) have been used to evaluate the geometry, dimensions, distribution and evolution of humid-tropical fluvial channel systems. Based on their seismic expression, and variations in sinuosity and depth, we identify six fluvial channel types, which occur within eight, seismically-defined, 18-145 m thick depositional units. Each unit is characterized by a consistent vertical change in channel body geometry and dimensions as follows (bottom to top): (1) relatively large (300-3000 m wide and 15-45 m deep), straight-to-low-sinuosity channels and/or large incised valleys at their bases, and (2) smaller (75-250 m wide and 8-23 m deep), highly-sinuous channels at their tops. This cyclical stratigraphic architecture is interpreted as a mainly climatically-driven change in fluvial discharge and sediment supply, rather than by eustatically- or tectonically-driven changes in relative sea-level based on (i) the study area was located far upstream (c. 700 km) of the coeval shoreline, and (ii) tectonically-quiescent nature of the basin during the Pleistocene to Recent. Although, the upstream control were likely the main control on the stratigraphic organization (Units 2-4 and 6), the large incised valleys (Units 5 and 7) are interpreted to be formed due a relative sea-level fall during the Last Glacial Maximum (LGM). This study demonstrates how an improved understanding of the temporal and spatial variability of fluvial channel systems can be obtained through detailed analysis of regionally-extensive, high-resolution 3D seismic reflection data. In particular, regional constraints on channel geometry, scale and orientation can be more confidently determined than is typically permitted b

Journal article

jordan OD, Gupta S, Hampson GJ, johnson HDet al., 2016, Preserved stratigraphic architecture and evolution of a net-transgressive mixed wave- and tide-influenced coastal system: Cliff House Sandstone, northwestern New Mexico, USA, Journal of Sedimentary Research, Vol: 86, Pages: 1399-1424, ISSN: 1527-1404

The Cretaceous Cliff House Sandstone comprises a thick (400 m) net-transgressive succession representing a mixed wave- and tide-influenced shallow-marine system that migrated episodically landwards. This study examines the youngest part (middle Campanian) of the Cliff House Sandstone, exposed in Chaco Cultural Natural Historical Park, northwest New Mexico, U.S.A. Detailed mapping of facies architecture between a three-dimensional network of measured sections has allowed the character, geometry, and distribution of key stratigraphic surfaces and stratal units to be reconstructed. Upward-shallowing facies successions (parasequences) are separated by laterally extensive transgressive erosion (ravinement) surfaces cut by both wave and tide processes. Preservation of facies tracts in each parasequence is controlled by the depth of erosion and migration trajectory of the overlying ravinement surfaces. In most parasequences, there is no preservation of the proximal wave-dominated facies tracts (foreshore, upper-shoreface), resulting in thin (4–7 m) top-truncated packages. Four distinct shallow marine tongues (parasequence sets) have been identified, consisting of ten parasequences with a total stratigraphic thickness of ~ 100 m. Each tongue records an episode of complex shoreline migration history (multiple regressive–transgressive phases) in an overall net-transgressive system. The ravinement surfaces provide a stratigraphic framework in which to understand partitioning of tide- and wave-dominated deposits in a net-transgressive system, and a model is presented to account for the sediment distribution and stratigraphic architecture observed in each parasequence. Despite a complex internal architecture, parasequences exhibit a predictable pattern which can be related to the regressive and transgressive phases of deposition. Preservation of wave-dominated facies tracts is associated with shoreline regression, while tide-dominated facies tracts are interpreted to

Journal article

van Cappelle M, Ravnås R, Hampson GJ, Johnson HDet al., 2016, Depositional evolution of a progradational to aggradational, mixed-influenced deltaic succession: Jurassic Tofte and Ile formations, southern Halten Terrace, offshore Norway, Marine and Petroleum Geology, Vol: 80, Pages: 1-22, ISSN: 0264-8172

Predicting the hydrodynamics, morphology and evolution of ancient deltaic successions requires the evaluation of the three-dimensional depositional process regime based on sedimentary facies analysis. This has been applied to a core-based subsurface facies analysis of a mixed-energy, clastic coastal-deltaic succession in the Lower-to-Middle Jurassic of the Halten Terrace, offshore mid-Norway. Three genetically related successions with a total thickness of 100–300 m and a total duration of 12.5 Myr comprising eight facies associations record two initial progradational phases and a final aggradational phase. The progradational phases (I and II) consist of coarsening upward successions that pass from prodelta and offshore mudstones (FA1), through delta front and mouth bar sandstones (FA2) and into erosionally based fluvial- (FA3) and marine-influenced (FA4) channel fills. The two progradational phases are interpreted as fluvial- and wave-dominated, tide-influenced deltas. The aggradational phase (III) consists of distributary channel fills (FA3 and FA4), tide-dominated channels (FA5), intertidal to subtidal heterolithic fine-grained sandstones (FA6) and coals (FA7). The aggradational phase displays more complex facies relationships and a wider range of environments, including (1) mixed tide- and fluvial-dominated, wave-influenced deltas, (2) non-deltaic shorelines (tidal channels, tidal flats and vegetated swamps), and (3) lower shoreface deposits (FA8). The progradational to aggradational evolution of this coastal succession is represented by an overall upward decrease in grain size, decrease in fluvial influence and increase in tidal influence. This evolution is attributed to an allogenic increase in the rate of accommodation space generation relative to sediment supply due to tectonic activity of the rift basin. In addition, during progradation, there was also an autogenic increase in sediment storage on the coastal plain, resulting in a gradual autoretreat of

Journal article

Amir Hassan MH, Johnson HD, Allison PA, Abdullah WHet al., 2016, Sedimentology and stratigraphic architecture of a Mioceneretrogradational, tide-dominated delta system: BalingianProvince, offshore Sarawak, Malaysia, Geological Society, London, Special Publication

Journal article

Massart BYG, Jackson MD, Hampson GJ, Johnson HD, Legler B, Jackson CA-Let al., 2016, Effective flow properties of heterolithic, cross-bedded tidal sandstones: Part 1. Surface-based modeling, AAPG Bulletin, Vol: 100, Pages: 697-721, ISSN: 0149-1423

Tidal heterolithic sandstones are commonly characterized by millimeter- to centimeter-scale intercalations of mudstone and sandstone. Consequently, their effective flow properties are poorly predicted by (1) data that do not sample a representative volume or (2) models that fail to capture the complex three-dimensional architecture of sandstone and mudstone layers. We present a modeling approach in which surfaces are used to represent all geologic heterogeneities that control the spatial distribution of reservoir rock properties (surface-based modeling). The workflow uses template surfaces to represent heterogeneities classified by geometry instead of length scale. The topology of the template surfaces is described mathematically by a small number of geometric input parameters, and models are constructed stochastically. The methodology has been applied to generate generic, three-dimensional minimodels (9 m3 volume) of cross-bedded heterolithic sandstones representing trough and tabular cross-bedding with differing proportions of sandstone and mudstone, using conditioning data from two outcrop analogs from a tide-dominated deltaic deposit. The minimodels capture the cross-stratified architectures observed in outcrop and are suitable for flow simulation, allowing computation of effective permeability values for use in larger-scale models. We show that mudstone drapes in cross-bedded heterolithic sandstones significantly reduce effective permeability and also impart permeability anisotropy in the horizontal as well as vertical flow directions. The workflow can be used with subsurface data, supplemented by outcrop analog observations, to generate effective permeability values to be derived for use in larger-scale reservoir models. The methodology could be applied to the characterization and modeling of heterogeneities in other types of sandstone reservoirs.

Journal article

van Cappelle M, Stukins S, Hampson GJ, Johnson HDet al., 2016, Fluvial to tidal transition in proximal, mixed tide-influenced and wave-influenced deltaic deposits: Cretaceous lower Sego Sandstone, Utah, USA, Sedimentology, Vol: 63, Pages: 1333-1361, ISSN: 0037-0746

Facies models for regressive, tide-influenced deltaic systems are under-represented in the literature compared with their fluvial-dominated and wave-dominated counterparts. Here, a facies model is presented of the mixed, tide-influenced and wave-influenced deltaic strata of the Sego Sandstone, which was deposited in the Western Interior Seaway of North America during the Late Cretaceous. Previous work on the Sego Sandstone has focused on the medial to distal parts of the outcrop belt where tides and waves interact. This study focuses on the proximal outcrop belt, in which fluvial and tidal processes interact. Five facies associations are recognized. Bioturbated mudstones (Facies Association 1) were deposited in an offshore environment and are gradationally overlain by hummocky cross-stratified sandstones (Facies Association 2) deposited in a wave-dominated lower shoreface environment. These facies associations are erosionally overlain by tide-dominated cross-bedded sandstones (Facies Association 4) interbedded with ripple cross-laminated heterolithic sandstones (Facies Association 3) and channelized mudstones (Facies Association 5). Palaeocurrent directions derived from cross-bedding indicate bidirectional currents which are flood-dominated in the lower part of the studied interval and become increasingly ebb-directed/fluvial-directed upward. At the top of the succession, ebb-dominated/fluvial-dominated, high relief, narrow channel forms are present, which are interpreted as distributary channels. When distributary channels are abandoned they effectively become estuaries with landward sediment transport and fining trends. These estuaries have sandstones of Facies Association 4 at their mouth and fine landward through heterolithic sandstones of Facies Association 3 to channelized mudstones of Facies Association 5. Therefore, the complex distribution of relatively mud-rich and sand-rich deposits in the tide-dominated part of the lower Sego Sandstone is attributed to t

Journal article

Massart BYG, Jackson MD, Hampson GJ, Johnson HDet al., 2016, Effective flow properties of heterolithic, cross-bedded tidal sandstones: Part 2. Flow simulation, AAPG Bulletin, Vol: 100, Pages: 723-742, ISSN: 0149-1423

Tidal heterolithic sandstone reservoirs are heterogeneous at the sub-meter scale, due to the ubiquitous presence of intercalated sandstone and mudstone laminae. Core-plug permeability measurements fail to sample a representative volume of this heterogeneity. Here we investigate the impact of mudstone drape distribution on the effective permeability of heterolithic, cross-bedded tidal sandstones using three-dimensional (3D) surface-based “mini-models” that capture the geometry of cross-beds at an appropriate scale. The impact of seven geometric parameters has been determined: (1) mudstone fraction, (2) sandstone laminae thickness, (3) mudstone drape continuity, (4) toeset dip, (5) climb angle of foreset-toeset surfaces, (6) proportion of foresets to toesets, and (7) trough or tabular geometry of the cross-beds.We begin by identifying a representative elementary volume (REV) of 1 m3, confirming that the model volume of 9 m3 yields representative permeability values. Effective permeability decreases as the mudstone fraction increases, and is highly anisotropic: vertical permeability falls to c. 0.5% of the sandstone permeability at a mudstone fraction of 25%, while the horizontal permeability falls to c. 5% and c. 50% of the sandstone value in the dip (across mudstone drapes) and strike (parallel to mudstone drapes) directions, respectively. There is considerable spread around these values, because each parameter investigated can significantly impact effective permeability, with the impact depending upon the flow direction and mudstone fraction. The results yield improved estimates of effective permeability in heterolithic, cross-bedded sandstones, which can be used to populate reservoir-scale model grid blocks using estimates of mudstone fraction and geometrical parameters obtained from core and outcrop-analog data.

Journal article

Alqahtani FA, Johnson HD, Jackson CA-L, Som RBet al., 2015, Nature, origin and evolution of a Late Pleistocene incised valley-fill, Sunda Shelf, Southeast Asia, Sedimentology, Vol: 62, Pages: 1198-1232, ISSN: 1365-3091

Shallow (<500 ms TWT/c. 500 m sub-sea) 3D seismic reflection data from a large (11500 km2), ‘merge’ survey, supplemented with high-resolution site survey data, have enabled identification and characterisation of a large (up to 18 km wide by 80 m deep) Late Pleistocene incised valley on the Sunda Shelf, offshore eastern Malaysia. The valley-fill displays five large-scale stratigraphic features: (1) it is considerably larger than other seismically-resolvable channel forms and can be traced for at least 180 km along its length within the available 3D seismic volume; (2) it is located in the axial part of the Malay Basin with a_NNW-SSE orientation, which is parallel to the maximum thickness of the underlying Oligo-Miocene succession (the main fill of the Malay Basin); (3) the youngest fill of the valley-fill is dominated by a large (up to 800 m wide and 23 m deep), high-sinuosity channel, with well-developed lateral accretion surfaces, point bars and meander loop cut-offs; (4) the immediately adjacent interfluves contain much smaller, dendritic ‘tributary’ channel systems, which drain into the larger incised valley system, and (5) a ca. 16 m thick, shell-bearing, Holocene age clay caps the valley-fill. Site survey borehole data from the abandonment part of the large meandering channel at the top of the incised valley-fill display the following: (1) pebbles, gravels and cobbles form a basal channel lag above a prominent, seismically-defined erosional surface; .(2) interbedded fine-grained sandstones and claystones, with shell fragments and terrestrially-derived organic material, form the middle part of the channel-fill; and (3) inclined heterolithic stratification (IHS), visible on high-resolution site survey seismic data, is the dominant macro-scale sedimentary structure. The interval adjacent to the incised valley comprises muds and silts with dispersed plant material and shell debris. These data document two major depositional environments

Journal article

Hampson GJ, Morris JE, Johnson HD, 2015, Synthesis of time-stratigraphic relationships and their impact on hydrocarbon reservoir distribution and performance, Bridport Sand Formation, Wessex Basin, UK, Editors: Smith, Bailey, Burgess, Fraser, Publisher: GEOLOGICAL SOC PUBLISHING HOUSE, Pages: 199-222

Book chapter

Legler B, Hampson GJ, Jackson CA, Johnson HD, Sarginson M, Ravnas Ret al., 2014, Facies relationships and stratigraphic architecture of distal, mixed tide-and-wave-influenced deltaic deposits: lower Sego Sandstone, western Colorado, Journal of Sedimentary Research, Vol: 84, Pages: 605-625, ISSN: 1527-1404

The facies characteristics and stratigraphic architectures of ancient mixed, wave- and tide-influenced deltas are poorly documented, despite the abundance of analogous modern shorelines. This paper presents the first facies analysis and stratigraphic-architectural characterization of the distal part of the Cretaceous lower Sego Sandstone (Book Cliffs, Colorado, U.S.A.), whose correlative proximal part is arguably the most comprehensively documented example of ancient deltaic strata that exhibit evidence for the activity of tides and waves.The distal lower Sego Sandstone consists of tide-dominated and wave-dominated deposits arranged within four regressive–transgressive tongues bounded by flooding surfaces. The proximal part of each regressive–transgressive tongue contains tide- dominated sandstones that sharply to erosionally overlie, and laterally interfinger with, wave-dominated deposits in the distal part of the tongue. Tide-dominated sandstones are fine to medium grained, and comprise wavy bedded and cross-bedded sandstones with abundant mud drapes, reactivation surfaces, and bidirectional, ebb- and flood-tide-directed paleocurrents. They define active tidal distributary channel-fill and nonchannelized tidal-bar deposits of similar lithologic character, which represent the proximal part of the delta front. Abandoned tidal distributary channel fills comprise intensely bioturbated mudstones. The outer, paleoseaward parts of tidal bars contain direct evidence for mixed tide and wave influence in the form of hummocky cross-stratified, very fine-grained sandstone beds intercalated with cross-bedded, fine- to medium-grained sandstones containing tidal indicators. These deposits locally pass paleoseaward into low-angle and hummocky cross-stratified sandstones with grain size and texture similar to tidal-bar deposits, implying reworking by storm waves. Wave-dominated deposits consist of coarsening-upward successions of mudstone and hummocky cross-stratified

Journal article

Bowman AP, Johnson HD, 2014, Storm-dominated shelf-edge delta successions in a high accommodation setting: The palaeo-Orinoco Delta (Mayaro Formation), Columbus Basin, South-East Trinidad, SEDIMENTOLOGY, Vol: 61, Pages: 792-835, ISSN: 0037-0746

Journal article

Zakaria AA, Johnson HD, Jackson CAL, Tongkul Fet al., 2013, Sedimentary facies analysis and depositional model for the Palaeogene West Crocker submarine fan system, NW Borneo, Journal of Asian Earth Sciences, Vol: 76, Pages: 283-300

This study outlines a sedimentological analysis of the Palaeogene West Crocker Formation (WCF) around the Kota Kinabalu area of SW Sabah, which represents a large submarine fan depositional system within part of what was the complex and tectonically active margin of NW Borneo. The newly acquired and often extensive outcrop data summarised in this study has resulted in a more complete synthesis of the Crocker fan depositional system than has been previously possible. Seven facies (F1 to F7) have been identified which constitute three main facies groups: (1) sand-dominated facies (F1 to F3), comprise high- to low-density turbidites and form the dominant part of the WCF, (2) debris flow-dominated facies (F4 to F6) comprises mud- and sand-dominant debris flows and mass transport deposits (MTD), which form a secondary but highly distinctive part of the WCF, and (3) mudstone-dominated facies (F7), represent a subordinate part of the WCF. Analysis of the vertical facies successions (from proximal to distal), has resulted in recognition of five major genetic units: (1) Channel-levee complex; characterised by thick (30-60 m) thinning and fining upward facies succession, which are dominated in their lower part by thick-bedded (1-6 m), amalgamated high-density (Lowe-type) turbidites with rare debrite beds; the upper part is dominated low-density (Bouma-type) turbidites, without associated debrite beds. (2) Channelised lobes; characterized by 2-10 m thick, coarsening upward, which are overlain by 5-20 m thick fining upward facies successions; these successions are dominated by high-density turbidites (c. 0.5-1 m thick) and linked co-genetic turbidite-debrite beds (0.1-0.5 m thick), with subordinate mudstone facies. (3) Non-channelised lobes; comprise 5-20 m thick coarsening upward facies successions; these start with mudstone facies, which pass gradually upwards into linked co-genetic turbidite-debrite beds; sandstone bed thickness increases upwards, while the debrite caps tend

Journal article

Legler B, Johnson HD, Hampson GJ, Massart BYG, Jackson CAL, Jackson MD, El-Barkooky A, Ravnas Ret al., 2013, Facies model of a fine-grained, tide-dominated delta: lower Dir Abu Lifa Member (Eocene), Western Desert, Egypt, Sedimentology, Vol: 60, Pages: 1313-1356

Existing facies models of tide-dominated deltas largely omit fine-grained, mud-rich successions. Sedimentary facies and sequence stratigraphic analysis of the exceptionally well-preserved Late Eocene Dir Abu Lifa Member (Western Desert, Egypt) aims to bridge this gap. The succession was deposited in a structurally controlled, shallow, macrotidal embayment and deposition was supplemented by fluvial processes but lacked wave influence. The succession contains two stacked, progradational parasequence sets bounded by regionally extensive flooding surfaces. Within this succession two main genetic elements are identified: non-channelised tidal bars and tidal channels. Non-channelised tidal bars comprise coarsening-upward sand bodies, including large, downcurrent-dipping accretion surfaces, sometimes capped by palaeosols indicating emergence. Tidal channels are preserved as single-storey and multilateral bodies filled by: (i) laterally migrating, elongate tidal bars (inclined heterolithic strata, 5 to 25 m thick); (ii) forward-facing lobate bars (sigmoidal heterolithic strata, up to 10 m thick); (iii) side bars displaying oblique to vertical accretion (4 to 7 m thick); or (iv) vertically-accreting mud (1 to 4 m thick). Palaeocurrent data show that channels were swept by bidirectional tidal currents and typically were mutually evasive. Along-strike variability defines a similar large-scale architecture in both parasequence sets: a deeply scoured channel belt characterised by widespread inclined heterolithic strata is eroded from the parasequence-set top, and flanked by stacked, non-channelised tidal bars and smaller channelised bodies. The tide-dominated delta is characterised by: (i) the regressive stratigraphic context; (ii) net-progradational stratigraphic architecture within the succession; (iii) the absence of upward deepening trends and tidal ravinement surfaces; and (iv) architectural relations that demonstrate contemporaneous tidal distributary channel infill and ti

Journal article

Lonergan L, Jamin NH, Jackson CA-L, Johnson HDet al., 2013, U-shaped slope gully systems and sediment waves on the passive margin of Gabon (West Africa), Marine Geology, Vol: 337, Pages: 80-97

3-D seismic reflection data has enabled the documentation of a system of remarkable modern and buried u-shaped gullies which intimately co-exist with upslope migrating sediment waves along 80 km of the Gabon continental slope. The modern gullies occur on a silty mud-dominated slope in water depths of 150–1500 m on an ~50 km wide slope with a gradient of 4.5° decreasing to 1.5°. The gully sets persist laterally for distances of at least 40 km and extend downslope for distances of up to 60 km. The gullies are u-shaped in crosssection,with a relief of 5–30 m, and widths of 50–400 m. Intriguingly, the gullies become narrower andshallower with distance down the slope, as well as increasing in number down slope. The majority of the gullies appear to be erosional but some appear to have resulted from simultaneous aggradation along inter-gully ridges and non-deposition along the adjacent gully floor. Hence, these gullies are interpreted to have formed mainly inresponse to spatially-variable deposition, rather than erosion. Upslope migrating sediment waves occur in close proximity to the gullies. Gullies cross fields of sediment waves and waves are observed to migrate up-slopelocally within both the erosional and aggradational gullies. Evidence is lacking for any slumping or headward erosion in the headwall region of the gullies, which discounts formation by very local sediment gravity flowsoriginating from shelf-edge collapse, as has been observed in other v-shaped gully systems. Based on our new data, and supported by theoretical studies on the mechanics of turbidity currents, we propose that the gulliesand related sediment waves were formed by diffuse, sheet-like, mud-rich turbidity currents that presumably originated on the shelf. Instabilities in the turbidity currents generated a wave-shaped perturbation in a crossflow direction leading to regularly spaced regions of faster and slower flow. For the non-aggradational and erosional gullies it is

Journal article

Massart BYG, Jackson MD, Hampson GJ, Legler B, Johnson HD, Jackson CAL, Ravnas R, Sarginson Met al., 2011, Three-dimensional Characterization and Surface-based Modeling of Tide-dominated Heterolithic Sandstones, EAGE

Conference paper

Jackson CA-L, Johnson HD, Zakaria AA, Tongkul F, Crevello PDet al., 2009, Sedimentology, stratigraphic occurrence and origin of linked debrites in the West Crocker Fm (Oligo-Miocene), Sabah, NW Borneo, Marine and Petroleum Geology, Vol: 26, Pages: 1957-1973

The West Crocker Fm (Oligocene-Early Miocene), NW Borneo, consists of a large (>20000 km2) submarine fan deposited as part of an accretionary complex. A range of gravity-flow deposits are observed, the most significant of which are mud-poor, massive sandstones interpreted as turbidites and clast-rich, muddy sandstones and sandy mudstones interpreted as debrites. An upward transition from turbidite to debrite is commonly observed, with the contact being either gradational and planar, or sharp and highly erosive. Their repeated vertical relationship and the nature of the contact between them, these intervals are interpreted as being deposited from one flow event which consisted of two distinct flow phases (fully turbulent turbidity current and weakly turbulent to laminar debris flow). The associated bed is called a co-genetic turbidite-debrite, with the upper debrite interval termed a linked debrite. Linked debrites indicates are best developed in the non-channelised parts of the fan system, and are absent to poorly-developed in the proximal channel-levee and distal basin floor environments. Due to outcrop limitations, the genesis of linked debrites within the West Crocker Formation is unclear. Based on clast size and type, it seems likely that a weakly turbulent to laminar debris-flow flow phase was present when the flow event entered the basin. A change in flow behaviour may have led to deposition of a sand-rich unit with ‘turbidite’ characteristics, which was subsequently overlain by a mud-rich unit with ‘debrite’ characteristics. Flow transformation may have been enhanced by the disintegration and incorporation into the flow of muddy clasts derived from the upstream channel floor, channel mouth or from channel levee collapse. Lack of preservation of this debrite in proximal areas may indicate either bypass of this flow phase or that the available outcrops fail to capture the debris flow entry point. Establishing robust sedimentological c

Journal article

Jackson CA-L, Johnson HD, 2009, Sustained turbidity currents and their interaction with debrite-related topography; Labuan Island, offshore NW Borneo, Malaysia, Sedimentary Geology, Vol: 219, Pages: 77-96

The Temburong Fm (Early Miocene), Labuan Island, offshore NW Borneo, was deposited in a lower-slope to proximal basin-floor setting, and provides an opportunity to study the deposits of sustained turbidity currents and their interaction with debrite-related slope topography. Two main gravity-flow facies are identified; (i) slump-derived debris-flow deposits (debrites) - characterised by ungraded silty mudstones in 1.5 to >60 m thick beds which are rich in large (>5 m) lithic clasts; and (ii) turbidity current deposits (turbidites) - characterised by medium-grained sandstone in beds up to 2 m thick, which contain structureless (Ta) intervals alternating with planar-parallel (Tb) and current-ripple (Tc) laminated intervals. Laterally discontinuous, cobble-mantled scours are also locally developed within turbidite beds. Based on these characteristics, these sandstones are interpreted as having been deposited from sustained turbidity currents. Cobble-mantled scours indicate periods of intense turbidity current waxing. The sustained turbidity currents are interpreted to have been derived from retrogressive collapse of sand-rich mouth bars (breaching) or directly from river effluent (hyperpycnal flow). Analysis of the stratal architecture of the two facies indicates that routing of the turbidity currents was influenced by topographic relief developed at the top of underlying debrite Turbidite beds are locally eroded at the base of an overlying debrite, possibly due to clast-related substrate ‘ploughing’ during the latter flow event. This study highlights the difficulty in constraining the origin of sustained turbidity currents in ancient sedimentary sequences. In addition, this study documents the importance large debrites may have in generating topography on submarine slopes and influencing routing of subsequent turbidity current and the geometry of their associated deposits.

Journal article

Hampson GJ, Sixsmith PJ, Kieft RL, Jackson CA-L, Johnson HDet al., 2009, Quantitative analysis of net-transgressive shoreline trajectories and stratigraphic architectures: mid-to-late Jurassic of the North Sea rift basin, Basin Research, Vol: 21, Pages: 528-558

This paper outlines the use of the shoreline trajectory concept to understand the controls on net-transgressive reservoir distribution and architecture in the highly productive Middle and Late Jurassic plays in the North Sea. Two broad groups of regressive–transgressive sandstone tongue are identified, with distinctive geometries, architectures and values of net-transgressive shoreline trajectory defined by the stacking arrangement of multiple tongues. Shoreface tongues were supplied by longshore-transported, marine-reworked sediment and are associated with low-to-moderate transgressive trajectories (typically <0.2°). These tongues have variable dip extents that decrease weakly as the angle of shoreline trajectory increases, relatively small thicknesses that increase weakly with the angle of transgressive trajectory, and partial or no overlap with underlying and overlying tongues down depositional dip. Deltaic-to-estuarine tongues were supplied directly by fluvial sediment and are associated with moderate-to-very high transgressive trajectories (typically >0.1°). These tongues have small dip extents, variable thicknesses that increase weakly with the angle of transgressive trajectory, and partial to full overlap with underlying and overlying tongues down depositional dip, although vertically stacked tongues are separated by thin mudstones over much of their extents. There is some overlap in geometry and stacking arrangement of these two groups of sandstone tongues. The temporal and spatial distribution of shoreface and deltaic-to-estuarine sandstone tongues reflects linked variations in tectonic subsidence and sediment routing within the evolving rift basin. Deltaic-to-estuarine tongues with moderate-to-very high transgressive trajectories were developed in rapidly subsiding fault-bounded depocentres supplied directly by fluvial sediment, whereas shoreface tongues with low-to-moderate transgressive trajectories characterised slowly subsiding faul

Journal article

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