Publications
103 results found
Doughty-Jones G, Mayall M, Lonergan L, 2017, Stratigraphy, facies and evolution of deep-water lobe complexes within a salt-controlled intra-slope mini-basin, AAPG Bulletin, Vol: 101, Pages: 1879-1904, ISSN: 0149-1423
A succession of four deep-water lobe complexes deposited within a salt-controlled minibasin have been imaged in unprecedented detail on high resolution, high frequency 3D seismic reflection data. The ponded interval was deposited over approximately 2.7 m.y. and consists of four discrete sequences, each of which contains one lobe complex. There is a systematic change in the shape and orientation of the lobe complexes through time: the two older lobe complexes are oriented broadly north-south and are up to 10 km (6.2 mi) long by 5 km (3.1 mi) wide, whereas the youngest lobe complexes are oriented southeast-northwest and have a rounder shape (9 km (5.6 mi) long by 8 km (5 mi) wide). The north to south migration of the feeder channel entry point and the change in lobe complex orientation is attributed to growth of the basin-bounding salt structures. Each lobe complex is composed of a feeder channel, multiple individual lobes formed of a trunk channel and a diverging network of smaller distributary channels, commonly fringed by a high amplitude band. The lobes are on average 1.6 km (1 mi) long by 1.3 km (0.8 mi) wide and are fed by trunk channels that range from 60 m (197 ft) to 200 m (656 ft) wide, with thicknesses up to 15 m (49 ft). Variation in lobe shape and spatial location is driven by the response of the lobes to topographic growth along the edge of the basin and as well as inherited seabed relief generated by previous lobe growth. In areas where lobe development is constrained by structural growth along the edge of the basin the lobes become elongated and divert away from the growing topography. Lobe complexes of similar scales have been described in detail in outcrops and in unconfined settings on the seafloor but this is the first study to describe these systems in such detail in the subsurface, resolving the individual lobes and lobe elem
Lonergan L, Jolly BA, Whittaker A, 2016, Growth history of fault-related folds and interaction with seabed channels in the toe-thrust region of the deep-water Niger delta, Marine and Petroleum Geology, Vol: 70, Pages: 58-76, ISSN: 0264-8172
The deep-water fold and thrust belt of the southern Niger Delta has prominent thrusts and folds oriented perpendicular to the regional slope that formed as a result of the thin-skinned gravitational collapse of the delta above overpressured shale. The thrust-related folds have grown in the last 12.8 Ma and many of the thrusts are still actively growing and influencing the pathways of modern seabed channels. We use 3D seismic reflection data to constrain and analyse the spatial and temporal variation in shortening of four thrusts and folds having seabed relief in a study area of 2600 km2 size in 2200–3800 m water depth. Using these shortening measurements, we have quantified the variation in strain rates through time for both fault-propagation and detachment folds in the area, and we relate this to submarine channel response. The total amount of shortening on the individual structures investigated ranges from 1 to 4 km, giving a time-averaged maximum shortening rate of between 90 ± 10 and 350 ± 50 m/Myr (0.1 and 0.4 mm/yr). Fold shortening varies both spatially and temporally: The maximum interval shortening rate occurred between 9.5 Ma and 3.7 Ma, and has reduced significantly in the last 3.7 Ma. We suggest that the reduction in the Pliocene-Recent fold shortening rate is a response to the slow-down in extension observed in the up-dip extensional domain of the Niger Delta gravitational system in the same time interval. In the area dominated by the fault-propagation folds, the channels are able to cross the structures, but the detachment fold is a more significant barrier and has caused a channel to divert for 25 km parallel to the fold axis. The two sets of structures have positive bathymetric expressions, with an associated present day uphill slope of between 1.5° and 2°. However, the shorter uphill slopes of the fault-propagation folds and increased sediment blanketing allow channels to cross these structures. Channels that develop coev
Wang X, Jardani A, Jourde H, et al., 2015, Characterisation of the transmissivity field of a fractured and karstic aquifer, Southern France, Advances in Water Resources, Vol: 87, Pages: 106-121, ISSN: 1872-9657
Geological and hydrological data collected at the Terrieu experimental site north of Montpellier, in a confined carbonate aquifer indicates that both fracture clusters and a major bedding plane form the main flow paths of this highly heterogeneous karst aquifer. However, characterising the geometry and spatial location of the main flow channels and estimating their flow properties remain difficult. These challenges can be addressed by solving an inverse problem using the available hydraulic head data recorded during a set of interference pumping tests.We first constructed a 2D equivalent porous medium model to represent the test site domain and then employed regular zoning parameterisation, on which the inverse modelling was performed. Because we aim to resolve the fine-scale characteristics of the transmissivity field, the problem undertaken is essentially a large-scale inverse model, i.e. the dimension of the unknown parameters is high. In order to deal with the high computational demands in such a large-scale inverse problem, a gradient-based, non-linear algorithm (SNOPT) was used to estimate the transmissivity field on the experimental site scale through the inversion of steady-state, hydraulic head measurements recorded at 22 boreholes during 8 sequential cross-hole pumping tests. We used the data from outcrops, borehole fracture measurements and interpretations of inter-well connectivities from interference test responses as initial models to trigger the inversion. Constraints for hydraulic conductivities, based on analytical interpretations of pumping tests, were also added to the inversion models. In addition, the efficiency of the adopted inverse algorithm enables us to increase dramatically the number of unknown parameters to investigate the influence of elementary discretisation on the reconstruction of the transmissivity fields in both synthetic and field studies.By following the above approach, transmissivity fields that produce similar hydrodynamic beh
Borgomeo E, Hebditch KV, Whittaker AC, et al., 2014, Characterising the spatial distribution, frequency and geomorphic controls on landslide occurrence, Molise, Italy, Geomorphology, Vol: 226, Pages: 148-161
Santos-Betancor I, Soto JI, Lonergan L, et al., 2014, 3D Geometry of an Active Shale-Cored Anticline in the Western South Caspian Basin, MATHEMATICS OF PLANET EARTH, Pages: 771-774, ISSN: 2193-8571
Santos-Betancor I, Ignacio Soto J, Lonergan L, et al., 2014, Gravity-Instabilities Processes and Mass-Transport Complexes During Folding: The Case of a Shale-Cored Anticline in the Western South Caspian Basin, MATHEMATICS OF PLANET EARTH, Pages: 775-778, ISSN: 2193-8571
Lonergan L, Jamin NH, Jackson CA-L, et 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
Martínez-García P, Comas M, Soto JI, et al., 2013, Strike-slip tectonics and basin inversion in the Western Mediterranean: the Post-Messinian evolution of the Alboran Sea, Basin Research, Vol: 25, Pages: 1-27
A comprehensive sediment thickness dataset consisting of single and multichannel seismic profiles integrated with bio-stratigraphic and log information from nearby DSDP and ODP wells have been used to constrain the late Messinian to Quaternary basin evolution of the central part of the Alboran Sea Basin. We find that deformation is heterogeneously distributed in space and time and that three major shortening phases have affected the basin as a result of continuous convergence between the Eurasian and African plates. During the Messinian salinity crisis, intense erosion and local subsidence resulted in the formation of small, isolated, basins with shallow marine and lacustrine sedimentation. The first shortening event occurred during the Early Pliocene (~5.33 to 4.57 Ma) along the Alboran Ridge. This was followed by a major transgression that widened the basin and allowed the increment of sediment accumulation rates. The second and main phase of shortening on the Alboran Ridge took place during the Late Pliocene (~3.28 to 2.59 Ma) as a result of thrusting and folding which was accompanied by a rotation of the Eurasian/African plate’s convergence vector from NW-SE to WNW-ESE. This phase also caused an uplift of the southern basins as well as right-lateral transtension along the WNW-ENE Yusuf fault zone. Deformation along the Yusuf and Alboran ridges continued during the early Pleistocene (~1.81 to 1.19 Ma) and the NNE-SSW trending Al-Idrisi strike-slip fault appears to be active at the present day. The Alboran Sea Basin is a region of complex interplay between sediment supply from the surrounding Betic and Rif mountains, and tectonics in a zone of transpression between the converging African and European plates. The partitioning of the deformation from the Pliocene onward and the resulting subsidence and uplift in the basin were controlled by the inherited pre-Messinian basin geometry.
Stewart MA, Lonergan L, Hampson G, 2013, 3D seismic analysis of buried tunnel valleys in the central North Sea: morphology, cross-cutting generations and glacial history, Quaternary Science Reviews, Vol: 72, Pages: 1-17, ISSN: 0277-3791
This work presents the results of morpho-stratigraphic analyses carried out on more than 180 buried tunnel valleys imaged in the central North Sea using 3D seismic data at a variety of resolutions. The buried tunnel valleys form complex networks of multiple cross-cutting generations. In the northern part of the study area, cross-cutting relationships within higher resolution 3D seismic data are used to extrapolate seven generations of tunnel valleys over an area of 14,400km2. Three generations of cross-cutting tunnel valleys are also observed within higher resolution 3D seismic data in the southern part of the study area. Detailed morphological measurements of individual tunnel valleys reveal average widths between 300m and 3000m, lengths in the region of tens of kilometres, and relatively straight and simple planform geometries. The majority of the tunnel valleys display undulating basal profiles which provide evidence for the uphill movement of water over distances greater than 10km and indicate formation by meltwater under pressure. Tunnel valley geometries vary between generations and defy a simple link between formation process and end form. Detailed orientation measurements for the tunnel valley generations reveal an overall NE-SW trend in the northern part of the study area, and a NW-SE directionality in the south. When considered in light of palaeoglaciological models for the British and Scandinavian ice sheets during the Pleistocene, tunnel valley orientation and distribution are consistent with the majority of tunnel valley generations forming perpendicular to a retreating British ice sheet. Changes in orientations between generations (in both northern and southern study areas) provide evidence for changes in the dynamics of the British and Scandinavian ice sheets between subsequent glaciations of the central North Sea.
Cairns G, Jakubowicz H, Lonergan L, et al., 2012, Using time-lapse seismic monitoring to identify trapping mechanisms during CO2 sequestration, International Journal of Greenhouse Gas Control, Vol: 11, Pages: 316-325
We show that it may be possible to distinguish between structurally- and capillary-trapped CO2 using time-lapse seismic monitoring of geological CO2 sequestration. Commercial reservoir simulation software was used to predict CO2 saturation in a saline aquifer over time. The output was combined with a rock physics model to calculate the elastic and seismic properties of the aquifer. As the seismic response depends on both fluid content and distribution, appropriate end-member fluid-distribution models were used to predict the possible range of seismic responses. We propose that different fluid-distribution models should be used for capillary- and structurally-trapped CO2 in a reservoir; the Hill average should be used for high, mobile CO2 saturations found during structural trapping whilst the Gassmann-Reuss average should be used for low, immobile CO2 saturations resulting from residual trapping. Far-offset seismic data was used to interpret reflections produced by the different trapping phases and cross-plotting was used to determine the trapping phase. Results indicate that structurally-trapped CO2 can be seismically imaged irrespective of fluid distribution and, importantly, a reflection may be generated off the interface between residually- and structurally-trapped CO2.
Stewart MA, Lonergan L, Hampson GJ, 2012, 3D Seismic Analysis of Buried Tunnel Valleys in the Central North Sea: Tunnel Valley Sedimentary Architecture, Glaciogenic Reservoirs and Hydrocarbon Systems, Editors: Huuse, Redfern, LeHeron, Publisher: Geological Society of London
Fourteen overlapping 3D seismic reflection data sets, originally acquired by the oil and gas industry, were used to image and investigate complex networks of buried tunnel valleys in theUK sector of the Central North Sea. More than 180 individual tunnel valleys were observed andmapped to horizontal resolutions of 12–50 m and vertical resolutions of 8–10 m. The resultspresented here identify three recurring seismic facies that locally define stratigraphic organization from base to top of the buried tunnel valley fills: (i) high-amplitude disrupted units, (ii) a unit containing gently dipping disrupted reflections or transparent facies and (iii) well-layered continuous reflections. A comparison to similar works in the region is used to infer tunnel valley infill during changing depositional conditions from high-energy subglacial meltwater toquiet glaciolacustrine or glaciomarine environments.
Jones G, Mayall M, Lonergan L, 2012, Contrasting depositional styles on a slope system and their control by salt tectonics - through-going channels, ponded fans and mass transport complexes., 32nd Annual GCSSEPM Foundation Bob F. Perkins Research Conference “New Understanding of the Petroleum Systems of Continental Margins of the World”’, Pages: 503-533
The infill history of a salt withdrawal mini-basin in the contractional domain of the gravity-driven salt system on the Angolan passive margin has been reconstructed using a high resolution three-dimensional seismic data-set. Well-constrained biostratigraphy has allowed calculation of the growth rate of the basin-bounding structures. Within the interval of stratigraphy investigated, the depositional style of sediments preserved in the basin has changed in response to changes in the rate of growth of the coeval, adjacent salt structures.During the early part of the basin history, sedimentation in the slope system was dominated by a series of erosional channel complex systems, which are 1-3 km wide and contain a preserved infill 100-200 m thick. The creation of sea floor topography by contemporaneous salt movement and the development of salt-cored anticlines caused the channels to be deflected, diverted, off-set, or incised deeply as they interacted with the developing slope topography.Subsequent salt movement, and a concomitant increase in the growth rate of the basin-bounding anticlines, led to more elevated topography and the development of extensive slumping of sediment into the basin centers, forming large mass transport deposits. As salt movement continued, the basin became largely enclosed; bound by a well-developed salt wall to the west and a series of complex salt structures to the east, where salt-cored anticlines developed laterally into salt diapirs. These complex structures controlled the flow pathways of sediment both into and out of the basin. The growth rate of the structures constraining the western margin of the basin slowed at this time, and as a result, sediment transported from the east by feeder channels formed ponded fan systems comprised of sheets of sand each formed by multiple small channels.Understanding the impact that active growth structures can have on sediment distribution and facies development is invaluable in the exploration and prod
Stewart MA, Lonergan L, 2011, Seven glacial cycles in the middle-late Pleistocene of northwest Europe: Geomorphic evidence from buried tunnel valleys, Geology, Vol: 39, Pages: 283-286
The deep-ocean marine isotope record and the Antarctic and Greenland ice caps record numerous glacial and interglacial cycles since the middle Pleistocene, and yet evidence for similar numbers of ice-sheet advances over the continent and shallow shelves of northwest Europe is absent. Here, we document seven generations of regionally correlatable subglacial tunnel valleys that record the geomorphic imprint of ice sheets traversing the North Sea basin between ca. 500 and 40 ka, consistent with that predicted by proxy records of glacial and interglacial climate change. Over 180 subglacial tunnel valleys that incise into Pleistocene sediments in the North Sea basin were mapped over ~60,000 km2 of three-dimensional seismic-reflection data. Using a subset of these data, we identified seven separate episodes of subglacial erosion that can be correlated regionally in the UK sector of the central North Sea. The characteristics of the valley morphologies, orientations, and infill stratigraphy indicate that each set of tunnel valleys formed during a separate ice-sheet advance and retreat cycle. Stratigraphic data suggest that the tunnel valleys formed significantly later than the Brunhes-Matuyama reversal event at 780 ka and before the Last Glacial Maximum (marine isotope stage [MIS] 2; 21 ka). These results imply a more complicated glacial history for northwest Europe and more glaciations than the three-glaciation model traditionally interpreted from the terrestrial record for the past 500 k.y. Our data provide the most complete documentary evidence for repeated advance and retreat of the northwest European ice sheets since the middle Pleistocene, and for the first time indicate that terrestrial ice-sheet advances in the North Sea can be matched in number with the cold events recorded in oceanic and/or ice-core proxies of climate change over the past 500 k.y.
Graham AGC, Stoker MS, Lonergan L, et al., 2011, The Pleistocene Glaciations of the North Sea Basin., Quaternary Glaciations -Extent and Chronoloogy. A closer Look, Editors: Ehlers, Gibbard, Amsterdm, Publisher: Elsevier, Pages: 261-278, ISBN: 978-0-444-53447-7
Mayall M, Lonergan L, Bowman A, et al., 2010, The response of turbidite slope channels to growth-induced seabed topography, AAPG BULLETIN, Vol: 94, Pages: 1011-1030, ISSN: 0149-1423
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- Citations: 75
Cairns C, Jakubowicz H, Lonergan L, et al., 2010, Sensitivity of seismic modelling to different fluid distributions for carbon capture and storage, Pages: 4247-4251
The ability of time-lapse seismic surveys to monitor carbon dioxide sequestration is explored using a rock physics model. We investigate the effects of reservoir depth on the seismic response, and its ability to detect CO2 and distinguish saturation changes. We examine the effect of the fluid distribution on the magnitude of the seismic response and the potential to use this to distinguish different reservoir models of CO2 distribution. This analysis suggests that the presence of CO2 can easily be found using traditional seismic surveys, with some potential to distinguish CO2 saturation and distribution. © 2010, European Association of Geoscientists and Engineers.
Cairns G, Jakubowicz H, Lonergan L, et al., 2010, Issues regarding the use of time-lapse seismic surveys to monitor CO<inf>2</inf> sequestration, Pages: 1236-1240
A rock physics model was built to provide a link between geological modeling, reservoir engineering and the time-lapse seismic response to CO2 injection. This model was used to examine the influence of factors such as reservoir depth and fluid distribution on the seismic attributes. Depth was shown to be an important control on the magnitude of the response, with the largest change found at shallow depths. Therefore a tradeoff is required between the need to sequester CO2 deeply for safety and the ability of seismic surveys to detect CO2. Synthetic zero-offset seismic showed a detectable change in response for small amounts of CO2 but this is heavily dependent on fluid distribution. The zero-offset response shows limited success distinguishing higher saturation changes and Amplitude Variation with Offset (AVO) may be required to provide this information. The distribution of the fluids in the reservoir was shown to be a significant control on the magnitude of the P-wave response and it’s the relationship with saturation. This may allow reservoir engineers to distinguish between mobile and immobile CO2, enhancing the understanding of the trapping in the reservoir. The ability to do this is heavily frequency dependent and may require high frequency seismic data such as cross-well tomography.
Mayall M, Lonergan L, others A, 2010, The response of turbidite channels to slope topography, AAPG Bulletin, Vol: 94, Pages: 1011-1030
Graham A, Lonergan L, Stoker MS, 2010, Depositional environments and chronology of Late Weichselian glaciation and deglaciation in the central North Sea., Boreas, Vol: 39, Pages: 471-491, ISSN: 0300-9483
Geological constraints on ice-sheet deglaciation are essential for improving the modelling of ice masses and understandingtheir potential for future change. Here, we present a detailed interpretation of depositional environmentsfrom a new 30-m-long borehole in the central North Sea, with the aim of improving constraints on the history of the marine Late Pleistocene British–Fennoscandian Ice Sheet. Seven units characterize a sequence ofcompacted and distorted glaciomarine diamictons, which are overlain by interbedded glaciomarine diamictons andsoft, bedded to homogeneous marine muds. Through correlation of borehole and 2D/3D seismic observations, we identify three palaeoregimes. These are: a period of advance and ice-sheet overriding; a phase of deglaciation; and aphase of postglacial glaciomarine-to-marine sedimentation. Deformed subglacial sediments correlate with a buriedsuite of streamlined subglacial bedforms, and indicate overriding by the SE–NW-flowing Witch Ground icestream. AMS 14C dating confirms ice-stream activity and extensive glaciation of the North Sea during the LastGlacial Maximum, between c. 30 and 16.2 14C ka BP. Sediments overlying the ice-compacted deposits have beenreworked, but can be used to constrain initial deglaciation to no later than 16.2 14C ka BP. A re-advance of Britishice during the last deglaciation, dated at 13.9 14C ka BP, delivered ice-proximal deposits to the core site and depositedglaciomarine sediments rapidly during the subsequent retreat. A transition to more temperate marineconditions is clear in lithostratigraphic and seismic records, marked by a regionally pervasive iceberg-ploughmarkederosion surface. The iceberg discharges that formed this horizon are dated to between 13.9 and 12 14C ka BP, and may correspond to oscillating ice-sheet margins during final, dynamic ice-sheet decay.
Graham A, Lonergan L, Stoker MS, 2008, Seafloor glacial features reveal the extent, and decay of the last British Ice Sheet, east of Scotland., Journal of Quaternary Science
Graham, A G C, Lonergan L, et al., 2007, Evidence for Late Pleistocene ice stream activity in the Witch Ground Basin, central North Sea, from 3D seismic reflection data, Quaternary Science Reviews, Vol: 26, Pages: 627-643, ISSN: 0277-3791
Acosta J, Velandia F, Osario J, et al., 2007, Strike-slip deformation within the Colombian Andes., Deformation of the Continental Crust: The Legacy of Mike Coward. Geological Society, London, Special Publications, Vol: 272, Pages: 303-319
Lonergan L, Jolly RJH, Rawnsley K, et al., 2007, Fractured Reservoirs, Publisher: Geological Society London, Special Publication No. 270, ISBN: 978-1-86239-213-7
Leckenby RJ, Lonergan L, Rogers SF, et al., 2007, Study of fracture-induced anisotropy from discrete fracture network simulation of well test responses., Fractured Reservoirs; Geological Society London Special Publication, Vol: 270, Pages: 117-137
Lonergan L, Borlandelli C, Taylor A, et al., 2007, The three-dimensional geometry of sandstone injection complexes in the Gryphon Field, United Kingdom, North Sea, Sand injectites: Implications for hydrocarbon exploration, Editors: Hurst, Cartwright, Publisher: AAPG, Pages: 103-112, ISBN: 9780891813682
Lonergan L, Maidment S, Collier J, 2006, Pleistocene subglacial tunnel valleys in the central North Sea basin: 3-D morphology and evolution, Journal of Quaternary Science, Vol: 21, Pages: 891-903, ISSN: 0267-8179
Leckenby RJ, Sanderson DJ, Lonergan L, 2005, Estimating flow heterogeneity in natural fracture systems, International Conference on Structures in the Continental Crust and Geothermal Resources, Publisher: ELSEVIER, Pages: 116-129, ISSN: 0377-0273
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- Citations: 26
Leckenby R, Lonergan L, Sanderson DJ, 2005, Estimating Flow Heterogeneity in Natural Fracture Systems. 148, 116-129, Journal of Volcanic and Geothermal Resources, Vol: 148, Pages: 116-129
Examples of small to medium scale fault systems have been mapped in Jurassic sedimentary rocks in north Somerset, England. These examples include contractional and dilational strike-slip oversteps as well as normal faults. These maps form the basis of calculations performed to investigate heterogeneity in natural fracture systems with the aim of predicting fluid flow localisation in different fault styles. As there is no way to measure fracture aperture directly, we use vein thickness to represent an integrated flow path or 'palaeo-aperture' from which we derive a representation of the flow distribution. Three different methods are used to estimate flow heterogeneity based on: (1) fracture density (the ratio of fracture length to area), (2) fracture aperture (fracture porosity) and (3) hydraulic conductance (fracture permeability normalised to the pressure gradient and fluid properties).Our results show that fracture density and hydraulic conductance are poorly correlated and that fracture density does not fully represent the natural heterogeneity of fracture systems. Fracture aperture and hydraulic conductance indicate stronger degrees of flow localisation. Different types of structures also seem to display characteristic and predictable patterns of heterogeneity. Normal fault systems show the highest magnitude of localisation along the faults rather than in the relay ramps, while contractional and dilational strike-slip systems show very strong localisation in the faults and oversteps, respectively. In all cases the amount of damage in the oversteps can modify such patterns of heterogeneity. (c) 2005 Elsevier B.V. All rights reserved.
Acosta J, Lonergan L, Coward MP, 2004, Oblique transpression in the western thrust front of the Colombian Eastern Cordillera, JOURNAL OF SOUTH AMERICAN EARTH SCIENCES, Vol: 17, Pages: 181-194, ISSN: 0895-9811
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- Citations: 26
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