Geometry and late-stage structural evolution of Central Graben salt diapirs, North Sea

Davison, Ian; Alsop, Ian; Birch, P. L.; Elders, Chris; Evans, Neil G.; Nicholson, H. Alleyne; Rorison, P.; Wade, D; Woodward, Jack; Young, Mike

doi:10.1016/s0264-8172(99)00068-9

Cited by 115 publications

(90 citation statements)

References 13 publications

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“…1a; e.g. Ode´, 1957;Squyres et al, 1992;Davison et al, 2000) and concentric extensional faults are most commonly associated with basin subsidence (Fig. 1e,f;Branney, 1995;Malthe-Sørenssen et al, 1999;Freed et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

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Implications of passive salt diapir kinematics for reservoir segmentation by radial and concentric faults

Stewart

2006

Marine and Petroleum Geology

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Section: Introductionmentioning

confidence: 99%

“…Oil and gas has long been produced from this setting, and partitioning of reservoirs by radial and concentric faults can challenge field development (Johnson and Bredeson, 1971;Davison et al, 2000). A question can be posed: are fault patterns predictable in areas that remain poorly imaged by seismic data, under salt overhangs for instance?…”

Section: Introductionmentioning

confidence: 99%

Implications of passive salt diapir kinematics for reservoir segmentation by radial and concentric faults

Stewart

2006

Marine and Petroleum Geology

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“…Although the controls on the external morphology of natural salt diapirs are relatively welldocumented and understood (e.g. Talbot, 1986, 1991;Vendeville and Jackson, 1992;Koyi, 1998;Davison et al, 2000;Jackson, 2007, 2011;Stewart, 2007), considerably less is known about their internal structure and kinematics for four key reasons: (i) well-exposed, natural salt diapirs are rare because halite, a key component of many salt structures, is highly soluble and dissolves, whereas anhydrite, upon contact with water, converts to gypsum, leaving a karstic soil or crust that masks the diapir's internal structure (Jackson et al, 1990;Bruthans et al, 2009); (ii) the internal structure of exposed diapirs can be strongly deformed by gravity spreading of salt extruding at the Earth's surface (Talbot and Jackson, 1987;Talbot, 1998;Talbot and Aftabi, 2004); (iii) even where diapirs are well exposed at the Earth's (Jackson et al, 1990). The intrasalt stratigraphy here is similar to that in the Santos Basin, with massive halite-dominated sequences being overlain by impure, interlayered evaporites (see Fig.…”

Section: Introductionmentioning

confidence: 99%

Enigmatic structures within salt walls of the Santos Basin—Part 1: Geometry and kinematics from 3D seismic reflection and well data

Jackson¹,

Jackson²,

Hudec³

et al. 2015

Journal of Structural Geology

151

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a b s t r a c tUnderstanding intrasalt structure may elucidate the fundamental kinematics and, ultimately, the mechanics of diapir growth. However, there have been relatively few studies of the internal structure of salt diapirs outside the mining industry because their cores are only partly exposed in the field and poorly imaged on seismic reflection data. This study uses 3D seismic reflection and borehole data from the São Paulo Plateau, Santos Basin, offshore Brazil to document the variability in intrasalt structural style in natural salt diapirs. We document a range of intrasalt structures that record: (i) initial diapir rise; (ii) rise of lower mobile halite through an arched and thinned roof of denser, layered evaporites, and emplacement of an intrasalt sheet or canopy; (iii) formation of synclinal flaps kinematically linked to emplacement of the intrasalt allochthonous bodies; and (iv) diapir squeezing. Most salt walls contain simple internal anticlines. Only a few salt walls contain allochthonous bodies and breakout-related flaps. The latter occur in an area having a density inversion within the autochthonous salt layer, such that upper, anhydrite-rich, layered evaporites are denser than lower, more halite-rich evaporites. We thus interpret that most diapirs rose through simple fold amplification of internal salt stratigraphy but that locally, where a density inversion existed in the autochthonous salt, RayleigheTaylor overturn within the growing diapir resulted in the ascent of less dense evaporites into the diapir crest by breaching of the internal anticline. This resulted in the formation of steep salt-ascension zones or feeders and the emplacement of high-level intrasalt allocthonous sheets underlain by breakout-related flaps. Although regional shortening undoubtedly occurred on the São Paulo Plateau during the Late Cretaceous, we suggest this was only partly responsible for the complex intrasalt deformation. We suggest that, although based on the Santos Basin, our kinematic model may be more generally applicable to other salt-bearing sedimentary basins.

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“…Over growing salt diapirs, overburden strata is commonly either thinned or completely removed by erosional processes, which accumulate eroded strata in peripheral salt withdrawal basins [Giles and Lawton, 2002]. Mass transport deposits (or MTDs) resulting from these erosional processes are usually mud dominated and have low exploration potential [Lee et al, 2004;Moscardelli et al, 2006;Posamentier and Kolla, 2003], except when sand-rich strata is present [Armitage et al, 2009;Beaubouef and Abreu, 2010;Davison et al, 2000b;Dunlap et al, 2010;Moraes et al, 2007;Moscardelli and Wood, 2008;Piper et al, 1997;Shanmugam et al, 1996;Tripsanas et al, 2008]. Important factors controlling the seal competence of MTDs include the presence of a strong structural fabric (including faults) in their interior, and variations in the degree of remobilization experienced by failed strata [Frey-Martínez et al, 2006].…”

Section: Introductionmentioning

confidence: 99%

Distribution and characterization of failed (mega)blocks along salt ridges, southeast Brazil: Implications for vertical fluid flow on continental margins

2011

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[1] Three-dimensional seismic data are used to assess the control of halokinetic structures on the distribution of blocks in a mass transport deposit in the Espírito Santo Basin, southeast Brazil. In contrast to what is commonly observed over growing salt structures, the thickness of the MTD-A1 is larger on top of a northwest trending salt ridge. Emphasis was given to the statistical analysis of 172 remnant and rafted blocks identified within Eocene mass transport deposits (MTD-A1). Three styles of block deformation are identified and scale relationships between the geometry of blocks and their relative position on the salt ridge are presented. Average block height reaches 130 m. Average block area reaches 0.43 km 2 , while 11.3% of the total area (A) investigated is covered by blocks (5% < A < 17%). On the basis of variations in block geometry (height, area, width/length ratio, orientation) and their relative distribution, we interpret that most failed strata have been remobilized by adjacent topography created during growth of the investigated salt ridge. We show that the origin of the blocks is linked to densely spaced sets of halokinetic-related faults that deformed the prefailure strata. The presence of underlying faults and blocks of remnant and rafted strata potentially induces sharp variations in the internal permeability of MTD-A1. Thus, the interpreted data shows that megablocks in MTDs can constitute viable fluid pathways on otherwise low-permeability units. This character can significantly decrease seal competence above and on the flanks of halokinetic structures.Citation: Gamboa, D., T. Alves, and J. Cartwright (2011), Distribution and characterization of failed (mega)blocks along salt ridges, southeast Brazil: Implications for vertical fluid flow on continental margins,

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Geometry and late-stage structural evolution of Central Graben salt diapirs, North Sea

Cited by 115 publications

References 13 publications

Implications of passive salt diapir kinematics for reservoir segmentation by radial and concentric faults

Implications of passive salt diapir kinematics for reservoir segmentation by radial and concentric faults

Enigmatic structures within salt walls of the Santos Basin—Part 1: Geometry and kinematics from 3D seismic reflection and well data

Distribution and characterization of failed (mega)blocks along salt ridges, southeast Brazil: Implications for vertical fluid flow on continental margins

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