Halokinetic rotating faults, salt intrusions, and seismic pitfalls in the petroleum exploration of divergent margins

Varela, Carlos L.

doi:10.1306/02261312164

Cited by 7 publications

(3 citation statements)

References 27 publications

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“…2). Hence, the structural framework of the Espírito Santo Basin comprises horsts and grabens below and Aptian evaporite unit, and supra-salt structures such as diapirs, salt rollers and rollovers, turtle anticlines, rafts and salt walls (Alves, 2012;Fiduk et al, 2004;Varela and Mohriak, 2013) (Figs. 2 and 3).…”

Section: Introductionmentioning

confidence: 99%

Corridors of crestal and radial faults linking salt diapirs in the Espírito Santo Basin, SE Brazil

Mattos

Alves

2018

Tectonophysics

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This work uses high-quality 3D seismic data to assess the geometry of fault families around salt diapir in SE Brazil (Espírito Santo Basin). It aims at evaluating the timings of fault growth, and suggests the generation of corridors for fluid migration linking discrete salt diapirs. Three salt diapirs, one salt ridge, and five fault families were identified based on their geometry and relative locations. Displacement-length (D-x) plots, Throw-depth (T-z) data and structural maps indicate that faults consist of multiple segments that were reactivated by dip-linkage following a preferential NE-SW direction. This style of reactivation and linkage is distinct from other sectors of the Espírito Santo Basin where the preferential mode of reactivation is by upwards vertical propagation. Reactivation of faults above a Mid-Eocene unconformity is also scarce in the study area. Conversely, two halokinetic episodes dated as Cretaceous and Paleogene are interpreted below a Mid-Eocene unconformity. This work is important as it recognises the juxtaposition of permeable strata across faults as marking the generation of fault corridors linking adjacent salt structures. In such a setting, fault modelling shows that fluid will migrate towards the shallower salt structures along the fault corridors first identified in this work.

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Section: Introductionmentioning

confidence: 99%

Corridors of crestal and radial faults linking salt diapirs in the Espírito Santo Basin, SE Brazil

Mattos

Alves

2018

Tectonophysics

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“…This apparent contradiction can be resolved if the sedimentation was fast enough to keep up with the differential vertical deformation. In this way, the sedimentary facies will reflect a near‐even sediment surface (ramp environment), while the subsurface structural geometry keeps changing and the deformation (even the smallest surface tilt) keeps causing sedimentary slumping and atectonic normal faulting (Maione & Pickford, 2001; Strauss et al., 2021; Varela & Mohriak, 2013). As the sedimentary load increases, the intensifying evaporite deformation should first lead to the observed onlap surfaces and pinch‐outs (Figure 11b), and finally to changes in the formation thicknesses and sedimentary facies in the salt‐bounded minibasins (Figure 11c).…”

Section: Discussionmentioning

confidence: 99%

Salt Tectonics Versus Shortening: Recognizing Pre‐Orogenic Evaporite Deformation in Salt‐Bearing Fold‐And‐Thrust Belts on the Example of the Silica Nappe (Inner Western Carpathians)

Oravecz,

Héja,

Fodor

2023

Tectonics

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Recognizing salt‐related structures and differentiating them from tectonic shortening‐related anticlines and synclines can be a very challenging task in salt‐bearing fold‐and‐thrust belts, especially in poor outcrop conditions. In this study, we explain several diagnostic structural and sedimentary features that may be used to distinguish pre‐orogenic halokinetic structures from shortening‐related structures on the example of the Silica Nappe (Inner Western Carpathians, Central Europe). Detailed structural mapping in this area resulted in the recognition of several pre‐orogenic salt‐related structures, including linear salt walls and minibasins. Initial evaporite movement started as early as the late Early Triassic, and widespread diapirism occurred during the Middle to Late Triassic, ultimately leading to facies differentiation, with carbonate platform growth in the subsiding minibasins and reduced basinal deposition on top of the diapirs. Later, the inherited salt structures localized the deformation during the Cretaceous Alpine orogeny, and exerted a strong control on the geometry and kinematics of the subsequent deformations. Our new interpretation explains previously unsolved structural problems in the Silica Nappe, like pre‐orogenic thickness variations during the post‐rift phase, frequent young‐on‐older type thrust contacts and multiple folding directions with variable vergencies. The results point out that the Silica Nappe is a fold‐and‐thrust belt, where pre‐orogenic salt tectonics and its effects on the fold‐and‐thrust belt evolution can be studied in detail.This article is protected by copyright. All rights reserved.

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“…Mud diapirs are formed by the expulsion of fluids from underlying strata, usually associated with fluid charge, gas and in the instance of mud volcanism by a ‘Christmas tree‐like’ form of extrusion (e.g. Varela & Mohriak, 2013). Here, within the available seismic data, neither gas nor the distinct ‘Christmas tree’ shapes are observed in the seismic for the study area.…”

Section: Discussionmentioning

confidence: 99%

Identification and differentiation of vertical movement through morphological changes and stratigraphic imprint: Two distinct uplifting mechanisms in the upper Calabrian accretionary wedge, western Ionian Sea

Pandolpho,

Urlaub,

Berndt

et al. 2023

Basin Research

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The seafloor morphology reflects both past and on‐going sedimentary, oceanographic and tectonic processes. Vertical movement is one of the drivers responsible for reshaping the seafloor through forming steep flanks that decrease slope stability, favour landslides, change current paths, form minibasins and control the sediment deposition, distribution and geometry. Here, we make use of these interactions to derive vertical movements and constrain the active tectonic processes at the western termination of the upper Calabrian accretionary wedge from the integrated analysis of bathymetric, backscatter, surface attributes and high‐resolution reflection seismic data. Within this area, we identify two types of deformational features and mechanisms that affect the depositional, erosional and tectonic processes at different scales. These include the deviation of channels, landslide scars, mass transport deposits (MTDs), separated drifts, sediment waves, lineaments and offset seafloor structures. The first type (long‐wavelength uplift) is an uplifted 22‐km‐wide region, in which seismic onlap relationships and the dip of deep reflectors suggest long‐lasting but slow tectonic uplift affecting sedimentation, and the second type (short‐wavelength uplift) includes three narrow elongated structures and one circular dome encircling the first region of uplift. We interpret that the first type of uplift feature was caused by tectonic deformation, while the second type is interpreted as formed by the fast uplift, tilting and faulting of modern sediments caused by diapirism due to rapid sedimentation in response to the first tectonically driven uplift. The study provides insight into the complex interaction of tectonic and sedimentary processes in the upper Calabrian accretionary wedge.

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Halokinetic rotating faults, salt intrusions, and seismic pitfalls in the petroleum exploration of divergent margins

Cited by 7 publications

References 27 publications

Corridors of crestal and radial faults linking salt diapirs in the Espírito Santo Basin, SE Brazil

Corridors of crestal and radial faults linking salt diapirs in the Espírito Santo Basin, SE Brazil

Salt Tectonics Versus Shortening: Recognizing Pre‐Orogenic Evaporite Deformation in Salt‐Bearing Fold‐And‐Thrust Belts on the Example of the Silica Nappe (Inner Western Carpathians)

Identification and differentiation of vertical movement through morphological changes and stratigraphic imprint: Two distinct uplifting mechanisms in the upper Calabrian accretionary wedge, western Ionian Sea

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