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Journal articleAas TE, Howell JA, Janocko M, et al., 2009,
Control of Aptian palaeobathymetry on turbidite distribution in the Buchan Graben, Outer Moray Firth, Central North Sea
, Marine and Petroleum Geology, Vol: 27, Pages: 412-434It is widely recognized that palaeobathymetry is a key control on the distribution of turbidite deposits. Thus, the utilisation of palaeobathymetric surfaces as an input for numerical turbidity current modelling offers a potentially powerful method to predict the distribution of deep marine sands in ancient (subsurface or outcrop) successions. Such an approach has been tested on an Aptian turbidite deposit from the Buchan Graben, UK Central North Sea, where modelled sand distributions could be quality controlled against available well data. Palaeobathymetric (base Aptian sand) surfaces are re-created from a surface-based 3D model by stepwise backstripping of post-Aptian overburden and removal of the post-depositional structural overprint. Key input parameters such as; (i) initial porosity and compaction factor assigned to the overburden and underburden; (ii) the restoration of structural overprint; and (iii) and the crustal response to removal of overburden (Airy vs. Flexural Isostasy), are associated with significant uncertainty. Thus, to assess this uncertainty, various palaeobathymetric surfaces are re-created by systematically modelling extreme values of individual input parameters. The effects of single input parameter variability on output surface morphology are quantified by spatial comparison of appropriate surfaces. Out of the 20 palaeobathymetric surfaces that were re-created, 3 were selected as input for process-based, numerical turbidity current simulations. The simulation software (Flow 3D™) uses computational fluid-dynamics (CFD) to model depositional patterns, while the effects of flow turbulence are simulated using the Renormalization-Group (RNG) model. The location of flow introduction into the model (sediment input point) as well as flow input parameters (volume of sediment, duration of flow, velocity, height and width) are fixed for all three surfaces to ensure that differences in flow behaviour and sand distribution can be attributed to spa
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Journal articleJackson CA-L, Johnson HD, Zakaria AA, et 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: 1957-1973The 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
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Journal articlePiggott MD, Farrell PE, Wilson CR, et al., 2009,
Anisotropic mesh adaptivity for multi-scale ocean modelling
, PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, Vol: 367, Pages: 4591-4611, ISSN: 1364-503X- Author Web Link
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- Citations: 63
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Journal articleCobden L, Goes S, Ravenna M, et al., 2009,
Thermochemical interpretation of 1-D seismic data for the lower mantle: The significance of nonadiabatic thermal gradients and compositional heterogeneity
, JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, Vol: 114, ISSN: 2169-9313- Author Web Link
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- Citations: 55
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Conference paperTsiampousi A, Zdravkovic L, Potts DM, 2009,
Modelling of overconsolidated unsaturated soils
, 4th Asia Pacific Conference on Unsaturated Soils, Publisher: CRC Press, Pages: 673-678Constitutive models for unsaturated soils are most commonly based on conventional critical state type models for saturated soils. The effect of partial saturation is taken into account through the intro-duction of an additional stress variable which depends on soil suction. The modified Cam-Clay surface is usu-ally assumed for the formulation of the yield and the plastic potential surfaces in the mean stress – deviatoric stress space. In this paper an existing model for unsaturated soils is used to simulate drained triaxial tests per-formed on highly overconsolidated unsaturated silt. Even though the model adopts an improved expression for the yield surface that allows a variety of shapes to be introduced, none of them can accurately simulate the observed soil behaviour in the laboratory tests. A new version of the model is, therefore, proposed and pre-sented here. Following the formulation and implementation of these alterations, analyses of laboratory ex-periments on artificial silt are presented demonstrating the improved simulation of soil behaviour.
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Journal articleBland PA, Jackson MD, Coker RF, et al., 2009,
Why aqueous alteration in asteroids was isochemical: High porosity ≠ high permeability
, EARTH AND PLANETARY SCIENCE LETTERS, Vol: 287, Pages: 559-568, ISSN: 0012-821X- Author Web Link
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- Citations: 109
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Journal articleFang F, Pain CC, Navon IM, et al., 2009,
A POD goal-oriented error measure for mesh optimization
, International Journal for Numerical Methods in Fluids, Vol: 63, Pages: 185-206, ISSN: 1097-0363The approach for designing an error measure to guide an adaptive meshing algorithm proposed in Power et al. (Ocean Modell. 2006; 15:3-38) is extended to use a POD adjoint-based method, thus facilitating efficient primal and adjoint integration in time. The aim is to obtain a new mesh that can adequately resolve all the fields at all time levels, with optimal (w.r.t. the functional) efficiency. The goal-based method solves both the primal and adjoint equations to form the overall error norms, in the form of a metric tensor. The tetrahedral elements are then optimized so that they have unit size in Riemannian space defined with respect to the metric tensor.This is the first attempt to use POD to estimate an anisotropic error measure. The metric tensor field can be used to direct anisotropic mesh adaptivity. The resulting mesh is optimized to efficiently represent the solution fields over a given time period. The calculation of the error measures is carried out in the reduced space. The POD approach facilitates efficient integration backwards in time and yields the sensitivity analysis necessary for the goal-based error estimates. The accuracy of both the primal and adjoint-reduced models is thus optimized (through the use of anisotropic mesh adaptivity). In addition, the functional for optimizing meshes has been designed to be consistent with that for 4D Var data assimilation.
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Journal articleJardine RJ, Zhu B, Foray P, et al., 2009,
EXPERIMENTAL ARRANGEMENTS FOR INVESTIGATION OF SOIL STRESSES DEVELOPED AROUND A DISPLACEMENT PILE
, SOILS AND FOUNDATIONS, Vol: 49, Pages: 661-673, ISSN: 0038-0806- Author Web Link
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- Citations: 30
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Journal articleKenkmann T, Collins GS, Wittmann A, et al., 2009,
A model for the formation of the Chesapeake Bay impact crater as revealed by drilling and numerical simulation
, Geological Society of America Special Paper, Vol: 458, Pages: 571-586 -
Journal articleGetsinger A, Rushmer T, Jackson MD, et al., 2009,
Generating High Mg-numbers and Chemical Diversity in Tonalite-Trondhjemite-Granodiorite (TTG) Magmas during Melting and Melt Segregation in the Continental Crust
, JOURNAL OF PETROLOGY, Vol: 50, Pages: 1935-1954, ISSN: 0022-3530- Author Web Link
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- Citations: 27
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Journal articleZhu B, Jardine RJ, Foray P, 2009,
THE USE OF MINIATURE SOIL STRESS MEASURING CELLS IN LABORATORY APPLICATIONS INVOLVING STRESS REVERSALS
, SOILS AND FOUNDATIONS, Vol: 49, Pages: 675-688, ISSN: 0038-0806- Author Web Link
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- Citations: 44
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Journal articleSech RP, Jackson MD, Hampson GJ, 2009,
Three-dimensional modeling of a shoreface-shelf parasequence reservoir analog: Part 1. Surface-based modeling to capture high-resolution facies architecture
, AAPG Bulletin, Vol: 93, Pages: 1155-1181, ISSN: 0149-1423 -
Journal articleJackson MD, Hampson GJ, Sech RP, 2009,
Three-dimensional modeling of a shoreface-shelf parasequence reservoir analog: Part 2. Geologic controls on fluid flow and hydrocarbon recovery
, AAPG BULLETIN, Vol: 93, Pages: 1183-1208, ISSN: 0149-1423- Author Web Link
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- Citations: 55
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Conference paperBarmpopoulos IH, Ho TYK, Jardine RJ, et al., 2009,
The large displacement shear characteristics of granular media against concrete and steel interfaces
, Amsterdam, Research Symposium on the Characterization and Behavior of Interfaces (CBI), Publisher: IOS Press, Pages: 17-24 -
Journal articleJackson 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: 77-96The 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.
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BookLiu JG, Mason P, 2009,
Essential Image Processing and GIS for Remote Sensing
, UK 9780470510322, Publisher: Wiley, ISBN: 9780470510322Essential Image Processing and GIS for Remote Sensing is an accessible overview of the subject and successfully draws together these three key areas in a ...
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Conference paperCiesla FJ, Davison TM, Collins GS, 2009,
Cooling of porous planetesimals after impacts: Implications for the thermal evolution of primitive bodies
, 72nd Annual Meeting of the Meteoritical-Society, Publisher: Meteoritical Society, Pages: A51-A51, ISSN: 1086-9379 -
Conference paperDavison TM, Collins GS, Ciesla F, 2009,
Quantifying heating in porous planetesimal collisions
, 72nd Annual Meeting of the Meteoritical-Society, Publisher: Meteoritical Society, Pages: A58-A58, ISSN: 1086-9379 -
Conference paperCollins GS, Wuennemann K, 2009,
NUMERICAL MODELING OF IMPACT EJECTION PROCESSES IN POROUS GEOLOGIC MATERIALS
, 72nd Annual Meeting of the Meteoritical-Society, Publisher: METEORITICAL SOC, Pages: A53-A53, ISSN: 1086-9379- Author Web Link
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- Citations: 2
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Journal articleHwang YK, Ritsema J, Goes S, 2009,
Spatial variations of P wave attenuation in the mantle beneath North America
, JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, Vol: 114, ISSN: 2169-9313- Author Web Link
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- Citations: 16
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