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The bases of active submarine channels are marked by large erosional features, such as knickpoints and plunge pools. However, their presence in ancient channel-fills has rarely been documented, so their importance in submarine channel morphodynamics requires investigation. Using seismic reflection data calibrated by wells from a buried submarine channel-fill, we document erosional features hundreds of metres long and tens of metres deep, here interpreted as knickpoints and a plunge pool, and provide a mechanistic process for their transfer into the stratigraphic record. Channel incision patterns are interpreted to record a transient uplift in an otherwise subsiding depocentre. Local structural complexities in the channel slope formed zones of preferential scouring. A switch to a depositional regime preserved the irregular channel base, inhibiting both the upstream migration of scours and smoothing of the channel base. The formation and preservation of these scours record the responses to salt tectonics and provide a unique snapshot of the formative processes of an ancient submarine channel. The presence of these exceptional basal scours indicates that headward erosion processes did not operate rapidly, challenging the paradigm that knickpoint migration controls channel evolution. Our results show that the primary erosion of the main channel surface and long-term channel evolution are both dominated by far more gradual processes. [ABSTRACT FROM AUTHOR]

Allogenic controls are frequently cited as key factors influencing basin evolution; however, fewer studies perform paleotopographic reconstructions to examine the impact of topography in the development of stratigraphic sequences. Disentangling how allogenic versus autogenic controls affect the stratigraphic succession within a basin affected by salt tectonics is particularly challenging because decoupling the stratigraphic signature of lithospheric induced uplift and subsidence from salt tectonics is not a trivial exercise. We tackle this problem by integrating physical modeling results with a landscape numerical model and compare results with a case scenario from the subsurface. The physical model provides surface displacement data that are then used as inputs into the landscape numerical model to simulate the surface and stratigraphic evolution of a salt tectonic basin during a 25-m.y. timespan and within the context of a continental-scale source-to-sink (S2S) system. Results show that the evolution of salt structures impact the development and diversion of sedimentary routing systems within salt basins, thus influencing the character of the stratigraphic record independently of allogenic factors such as lithospheric induced uplift. Modeling results highlight the importance of reconstructing the paleo-topography of ancient depositional systems affected by salt tectonics to truly understand the nature of the final stratigraphic record. [ABSTRACT FROM AUTHOR]

The article offers information on a 2D UHRS line between the Energy Island site and well IDA-1, showing the subsurface architecture and soil type predictions of Neogene to Quaternary deposits.

Triassic Keuper evaporites have long been recognized as the main detachment level for thrusting in the Pyrenean fold–thrust belts. The deformed Late Cretaceous–Eocene foreland basin of the Southern Pyrenees has structures and stratal geometries that can be interpreted as related to salt tectonics (e.g. unconformities, rapid thickness variations, long-lived growth fans and overturned flaps), although they have been overprinted by shortening and thrusting. Based on field observations and published maps, we build new structural cross-sections reinterpreting two classic transects of the Southern Pyrenees (Noguera Ribagorçana and Noguera Pallaresa river transects). The sequential restoration of the sections explores the variations in structural style, addressing the role of halokinesis in the tectonic and sedimentary development. In the Serres Marginals area, we propose that salt pillows and diapirs started developing locally during the Mesozoic pre-orogenic episode, evolving into a system of salt ridges and intervening synclines filled with early synorogenic sediments. Rapid amplification of folds recorded by widespread latest Cretaceous–Paleocene growth strata is taken as marking the onset of contractional folding in the area. During Pyrenean compression, folding mechanisms transitioned from dominantly halokinetic to a combination of buckling and differential sedimentary loading. Squeezing of salt diapirs and thrust welding occurred as salt ridges were unroofed. We provide new field observations that lead to a reinterpretation of the regional structural development and contribute to the debate about the role of salt tectonics in the Pyrenees. Supplementary material: Table S1, giving the thickness of the main stratigraphic units, is available at https://doi.org/10.6084/m9.figshare.c.5287737 [ABSTRACT FROM AUTHOR]

The Albian Gap is a uniquely large (up to 65 km wide and >450 km long), enigmatic salt-related structure in the Santos Basin, offshore Brazil. It is located near the basin margin and trends NE (i.e. subparallel to the Brazilian coastline). The gap is characterized by a near-complete absence of Albian strata above depleted Aptian salt. Its most remarkable feature is an equivalently large, equally enigmatic, basinward-dipping, supra-salt rollover that contains a post-Albian sedimentary succession that is up to 9 km thick. Owing to its unique geometry, size and counter-regional aspect, the origin and evolution of the Albian Gap has been the centre of debate for >25 years. This debate revolves around two competing models; that is, did it form as a result of thin-skinned (i.e. supra-salt) extension, or progradational loading and salt expulsion? The extension-driven model states that the Albian Gap (and overlying rollover) formed as a result of post-Albian gravity-driven extension accommodated by slip on a large, counter-regional, listric normal fault (the Cabo Frio Fault). Conversely, the expulsion-driven hypothesis states that the Albian Gap was established earlier, during the Albian, and that post-Albian deformation was controlled by differential loading, vertical subsidence and basinward salt expulsion in the absence of significant lateral extension. This study utilizes a large (c. 76 000 km2), dense (4–8 km line spacing), depth-migrated, 2D seismic dataset that fully covers and thus permits, for the first time, a detailed, quasi-3D structural analysis of the entire Albian Gap. In this study we focus on (1) the evolution of base-salt relief and the original salt thickness variations and (2) the geometry of the post-Albian rollover, and its related faults and salt structures. To constrain the kinematics of the Albian Gap, and how this relates to the evolution of the base-salt relief, we also apply novel structural restoration workflows that incorporate flexural isostasy, in addition to a detailed, sequential reconstruction of the intra-gap rollover sequences. Our results show that the geometry and kinematics of the Albian Gap vary along-strike, and that both post-Albian extension and expulsion play a significant role in its evolution. Basinward-dipping growth wedges, salt rollers and listric normal faults record extension, whereas sigmoidal wedges, halokinetic sequences and upturned near-diapir flaps, the latter two associated with large diapirs bounding the downdip edge of the gap, record basinward salt expulsion and inflation. Where the Albian Gap is relatively wide (>50 km), these processes alternate and operate at approximately equal proportions. Our results are consistent with the amount of basinward translation inferred from the analysis of ramp–syncline basins located downdip on the São Paulo Plateau. Our results seemingly reconcile one of the longest-running debates in salt tectonics, as well as having more general implications for understanding the regional kinematics and dynamics of salt-related structures in other salt basins, in particular the controls on the development of large, counter-regional faults. Supplementary material: Uninterpreted versions of the seismic sections are available at https://doi.org/10.6084/m9.figshare.c.5023088 [ABSTRACT FROM AUTHOR]

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Discusses how gravity causes salt to float up through heavier rocks, forming structures that often trap oil and gas. tendency for small irregularities on the salt surface grow into mounds that have a regular spacing; Contraction of the mounds into finger-shaped diapirs linked by polygonal salt ridges; Tendency for the rising diapirs to spread into flattened bulbs under a layer of uncompacted, lees dense sediment.

The Nordkapp Basin is a northeast-trending upper Paleozoic rift basin located in the western Barents Sea. The presence of salt structures makes this basin of interest for hydrocarbon exploration. Nevertheless, no commercial discoveries have been made so far, and the basin remains poorly understood in terms of distribution of reservoirs and source rocks within its salt minibasins. In this study, a three-dimensional data set together with well data in a small area located in the southwestern subbasin of the Nordkapp Basin has been studied, with the main purpose of obtaining a better understanding of salt kinematics and minibasin infill, with special focus on the Triassic. The minibasin infill of the Nordkapp Basin has been subdivided into five second-order sequences, which mark the main regional events recorded in the Barents Sea. Further subdivision into third-order sequences has been made in the Triassic in response to the local halokinetic movements of the basin. In terms of salt kinematics, the Nordkapp minibasins have been affected by the following: (1] late Permian-Early Triassic minor salt mobilization, (2) latest Early Triassic reactive diapirism, (3) Early to Middle Triassic transition between reactive-passive diapirism, (4) Middle Triassic-Jurassic passive diapirism, (5] Late Jurassic-Early Cretaceous gravity gliding, and (6) Cenozoic regional contraction. The rapid changes in depositional environment observed in well 7228/7-1 A, together with the large variability of seismic responses and reflection terminations, provide evidence of a complex Triassic paleogeography controlled by salt tectonics. Early to Middle Triassic differential loading of minibasins into the underlying salt formed broad diapir-induced highs, which might have acted as local sources of sediment for submarine debris flows and fan deltas developed adjacent to salt structures. During the Middle Triassic-Jurassic last stage of passive growth, salt diapirs formed local topographic highs covered by ephemeral roofs and caused narrow areas of deformation widths less than 1 km (3281 ft), developing composite halokinetic sequences. In minibasins, salt evacuations and associated subsidence controlled the spatial transgressive-regressive trends of fluviodeltaic systems coming from the southeast of the Barents Shelf. Rapidly subsiding minibasins were flooded by marine conditions, and intervals of organic-rich source rocks might have been deposited in salt withdrawalrelated depressions. As subsidence decreased, newly developed regressive sequences of northwest-trending fluviodeltaic systems sourced from the southeast covered previous marine environments, possibly depositing potential fluviodeltaic reservoirs within the salt minibasins. [ABSTRACT FROM AUTHOR]

The Romanian Carpathians are of global importance in salt tectonics because they host the type locality for the term "diapir." Although there are several historical reviews of worldwide salt tectonics, important aspects of how diapirism has been described and defined in the Romanian Carpathians are missing in these works. Many of these publications are difficult to access, and most are written in Romanian, German, French, or Polish. This paper aims to present in detail the original ideas and to describe the historical development of these concepts. We focus particularly on the work of the outstanding Romanian geologist, Ludovic Mrazec, who defined the folds with piercing core and coined the term diapir. [ABSTRACT FROM AUTHOR]

A new gravity survey (almost 900 new sites and more than 4000 sites from previous studies) reveals the existence of Pyrenean-oriented long-wavelength residual gravity anomalies ranging from -18 to 28 mGal, associated with frontal structures, and short-wavelength gravity lows (up to -16 mGal) distributed along an oblique zone in the western sector of the South Pyrenean Central Unit of the Spanish Pyrenees. These clearly correlate with the occurrence of several bodies and diapirs of Triassic evaporites and mudstones. The subsurface geometry and regional location of these evaporitic bodies is derived from four 2.5D gravity models that tie data from field geology, rock density analysis, seismic reflection profiles, boreholes and our gravity survey. Gravity-constrained cross-sections allow us to distinguish between vertically well-developed and poorly developed diapirs that belong to the Sierras Marginales Unit, and to characterize the relationships between thrusting and diapirism during Eocene-Oligocene time. [ABSTRACT FROM AUTHOR]

Peak-stress zones and pressure anomalies around wellbores through moving salt bodies threaten well integrity. Our study provides a conceptual framework to identify the depth of peak zones of shear stress in moving salt sheets, whether autochthonous or allochthonous. We use analytical methods to determine the principal stress magnitudes and stress-trajectory orientations caused by ductile creep in crystalline salt. The four basic flow types analyzed are Couette, Poiseuille, no-slip squeezing, and free-slip squeezing flow. The analytical formulae specify velocity gradients, shear-stress profiles, and principal stress trajectories. The analytical results are compared with detailed flow visualizations in numerical and physical models of salt tectonics to test our generic conclusions. We offer guidelines to optimize drilling operations in moving salt bodies. The study suggests that stress trajectories and zones of viscous stress peaks in salt layers should be mapped routinely during well planning, in addition to the traditional analysis of elastic stresses and safe mud-pressure windows for controlling wellbore stability. [ABSTRACT FROM AUTHOR]

The article focuses on the results of the ION Mid North Sea High (MNSH) Prime three-dimensional (3D) seismic survey of the Zechstein play in Great Britain. Topics discussed include the discovery of various halokinesis amounts in the Top Zechstein which affected the Bacton group Triassic strata, presence of karstification and sinkhole-type features in the Z3 Plattendolomit unit, and emergence of the Z2 Hauptdolomit as the most prospective reservoir.

This work discusses concepts related to the occurrence of salt along weakness planes, such as faults and fractures, which resemble igneous intrusions and may result in peculiar seismic features. We suggest that mechanisms for the formation of these structures basically involve the creation of extensional faults (commonly associated with crestal collapse grabens), which are rotated and migrated to structural flanks by domation, creatin interesting seismic features here referred to as halokinetic rotating faults. At the time of their formation, some of these faults may be incipiently intruded by salt as a way of relieving sporadic intense internal overpressure episodes in the salt body, by regional compression, and/or by buoyancy effects compensating the density difference between salt and surrounding sediments. The relatively low overburden pressure at the crest of the diapir and the original high dip angles of these fault planes favor salt intrusion near the diapir apex. The process may occur in several cycles along the salt dome evolution, creating several generations of salt apophyses positioned in the diapir apex and flanks, resulting in different dips and areas of extension. These intrusions sometimes resemble the branches of Christmas tree structures, which are commonly formed by extrusive mechanisms. Although well and seismic data point to the occurrence of salt along fault planes, we recognize that salt is not a low-viscosity fluid, and the mechanisms to allow its penetration along fault planes remain unknown. Some of the possible mechanisms which are commonly associated with a later phase of regional compression, are discussed in this work. [ABSTRACT FROM AUTHOR]

This study presents the results from the interpretation of an extensive and recent regional two-dimensional seismic survey focused on the understanding of the salt tectonics in the western Gulf of Cadiz (GoC). Two different salt units were identified: an autochthonous salt unit of the Late Triassic or the Early Jurassic (Hettangian) and an allochthonous unit that originated from the Hettangian salt. Interpretation of the pattern of distribution of the salt in the basin allowed subdivision of the area of study into three distinct salt domains: the eastern domain characterized by the presence of a conspicuous allochthonous salt nappe (Esperança Salt), the central domain dominated by salt diapirs with mild deformation of Miocene strata and wide salt-withdrawal minibasins, and the southwestern domain where present-day tectonics induces impressive salt deformation affecting the sea floor. This complex pattern is mainly the result of the interaction of inherited basement structure, complex tectonic history, and stress regime of the basin. The intense halokinesis observed has created several salt-related trap geometries and fluid migration pathways. As the focus of worldwide exploration along passive margins is gradually shifting to deep-water regions, the western GoC has the potential to become a deep-water petroleum province in the near future. [ABSTRACT FROM AUTHOR]

Prerift salt layers associated with extensional detachment faults exhuming mantle and deeper crustal rocks at the sea floor are observed in the Parentis and Arzacq-Mauléon basins located at the eastern termination of the Bay of Biscay. How detachment faults interact with salt in hyperextended rift systems is yet little understood. Based on field observations and drill-hole and seismic data, we propose a new model to explain the interaction between salt tectonics and extensional detachment systems. We demonstrate that the presence of a thick prerift salt layer in an area undergoing extreme crustal thinning can control the geometry and evolution of rift systems and obscure the rift-related structures in the underlying basement. During an initial stage of rifting, prerift salt layers act as a decoupling horizon between sub- and suprasalt units and hinder crustal detachment faults to cut through the salt layers and form breakaways at the sea floor. As a consequence, they sole out along the ductile salt layer and no subsalt material can be exhumed to the sea floor. Thus, sub- and suprasalt layers deform by different deformation modes, which makes that detachment fault difficult to identify on seismic images. In a later stage, when salt has migrated and thinned out, sub- and suprasalt layers can locally couple and detachment faults can be exposed at the surface, resulting in windows of exhumed basement surrounded by extensional allochthons formed by suprasalt sedimentary units. [ABSTRACT FROM AUTHOR]

Three-dimensional seismic-reflection data are used in the analysis of submarine channel systems in the Espirito Santo Basin, Brazil. The exceptional quality of the studied data set allows the detailed documentation of the geometry, regional distribution, and statistical parameters of salt-related normal faults, and their effect on the Rio Dace Canyon system (RDCS). On the Espirito Santo continental slope, normal faulting was triggered during early halokinesis (stage A) but barely controlled the initial evolution of the RDCS, which incised the continental slope axially within a salt-withdrawal basin. However, in a second stage (stage B), crestal or radial faults controlled erosion over growing salt structures, whereas synclinal and channel-margin fault sets dissected overbank strata to the RDCS. In the later part of stage B, channel sinuosity decreased sharply in response to fault activity and associated sea-floor destabilization. Vertical propagation of blind faults was triggered in a third stage (stage C), in association with crestal collapse of buried salt anticlines and regional diapirism, but synclinal and channel-margin faults did not propagate vertically above a regional unconformity marking the base of stage C strata. Statistical analyses of observed fault sets demonstrate that synclinal faults are in average 2.3 times longer than the crestal or radial types but record 60% of the throw (average 83 m [272 ft]) experienced by the latter. In addition, the fault sets are shown to have contributed to local cannibalization of the sea floor, vertical stacking of channel-fill strata, and structural and depositional compartmentalization of potential reservoir successions. As a result, channel systems show marked differences in mean values for sinuosity, height, and width in relation to five main phases of channel development. The structural setting in the study area differs from productive areas offshore Espirito Santo (e.g., Golfinho field), west Africa, and Gulf of Mexico, revealing in distal parts of the Brazilian margin the existence of local controls on submarine channel architecture and structural compartmentalization prior to the main stages of diapirism. [ABSTRACT FROM AUTHOR]

The Silverpit Crater consists of a set of concentric faults up to 20 km in diameter in the southern North Sea. Although formerly described as the first impact structure to be recognized in the UK, its spatial association with local tectonic and stratigraphic features suggests that it is unlikely to have been caused by a random extra-terrestrial event. This paper proposes a terrestrial origin for the Silverpit Crater as a Palaeogene pull-apart basin linked to strike-slip faulting in the Carboniferous basement. Faulting and thinning of Permian evaporites underlying the crater acted as a buffer to basement extension and caused both a flexural collapse of the overlying Triassic strata and circumferential listric faulting in the Cretaceous succession. Reactive diapirism in Lower Jurassic shales may have contributed to the formation of a central uplift at base Cretaceous level. The paper compares the tectonic setting of two contemporaneous strike-slip-related structures in southern England (Bovey Basin in Devon and the Compton Valence structure in Dorset) with that of the Silverpit Crater, and concludes by briefly considering whether a pull- apart model can help to explain the formation of Upheaval Dome, a similar putative impact structure in the Canyonlands National Park of Utah. [ABSTRACT FROM AUTHOR]

Restoration of a 375-km (230-mi)-long section across the Kwanza Basin, Angola, shows three stages of deformation detaching on Aptian salt, each caused by basement tectonics. First, tilting related to postrift thermal subsidence initiated early Albian deformation, shortly after salt deposition ended. Deformation waned in the late Albian, probably because of thinning of salt lubricant beneath the extensional province. The second phase of deformation was triggered by hitherto unrecognized crustal uplift beneath the continental rise around 75 Ma (Campanian). Uplift led to salt extrusion and seaward advance of the Angola salt nappe over the abyssal plain. Exposure of the nappe toe removed the buttress provided by abyssal-plain cover, which rejuvenated seaward translation. Third, Miocene basement uplift below the shelf steepened the bathymetric slope and greatly accelerated downslope translation. This deformation is now slowing because accelerated sedimentation on the abyssal plain reduced the relief of the system and blocked salt-nappe advance. Minor changes in basin configuration led to profound changes in detached deformation. Miocene uplift was only a few hundred meters on the shelf, but this was sufficient to destabilize the system and increase the translation rate from 300 to 3200 m/m.y. (980 to 10,500 ft/m.y.) Deposition of 600 m (2000 ft) of sediment on the abyssal plain in the upper Miocene shifted contractional deformation 150 km (95 mi) landward. We conclude that driving and resisting forces have been precariously balanced for much of the Kwanza Basin's history. [ABSTRACT FROM AUTHOR]

The lower Pliocene shallow-marine to continental succession of the Crotone Basin, a small forearc basin on the Calabrian Arc, Southern Italy, is represented by a mixed terrigenous-carbonate succession, up to 850 m thick, known as the Zinga Molasse, deposited in an active tectonic setting dominated by extensional structures and halokinesis. The succession may be informally subdivided into three main sequences, Zinga 1, Zinga 2, Zinga 3, each bounded by major unconformities produced by the interaction of tectonics and eustasy. The Zinga 1 sequence records terrigenous input into the basin leading to the development of stacked progradational wedges of shoreface and deltaic deposits. Spectacular thickness changes and progressive unconformities result from the activation of NE-trending growth folds and listric faults, and indicate that deposition occurred during extensional deformation and salt tectonics. However, the regional extent of the surfaces, the lack of evidence for changes in the local tectonic regime between sequences and the presence of listric faulting within sequences all favour eustatic sea-level change as the main control on the sequence development, although local tectonics strongly controlled sedimentary architecture. [ABSTRACT FROM AUTHOR]

Presents the schedule of several geological conventions, field courses and field seminars in 2004. Short course on Reservoir Engineering for Petroleum Geologists; Field course on the Fundamentals of the Seismic Sequence Stratigraphy of Fluvial-Deltaic and Turbiditic Depositional Systems; Field seminar on Salt Tectonics and Sedimentation of La Popa Basin, Mexico.

A calendar of events related to petroleum geology in 2015 is presented including the Geochemistry and Modeling of Unconventional Petroleum Systems in Melbourne, Victoria on September 13, the Fundamentals Education Conference in Houston, Texas from November 9-13, and the Practical Salt Tectonics event in Houston, Texas from December 1-4.

A calendar of events related to geosciences education is presented including a short course on pratical salt tectonics in Houston, Texas from November 4-7, 2013, workshop on reservoir quality in Austin, Texas from November 12-13, 2013, and Winter Education Conference in Houston, Texas from February 10-14, 2014.

A calendar of events for the geoscience sector in February-October 2010 is presented, including the "Winter Education Conference," the "Practical Salt Tectonics," and the "Assessment of Unconventional Shale Resources Using Geochemistry."

The article narrates how researchers of National Iranian Oil Co. modeled casing-point setting (CPS) depths at its RSH field to save as much as 15 percent using various tools and scenarios. It informs that the RSH field lies where salt tectonics dominates the development of structure. The article also details that three optimized well trajectory profile were proposed to solve the CPS problem.

Presents a calendar of events in the field of petroleum geology. A short course, Practical Salt Tectonics, will be offered in Dallas, Texas in June 2006. A field seminar entitled Complex Carbonates Reservoirs: The Relationship Between Facies and Fracturing begins in Naples and ends in Pescara, Italy in May 2006. The field seminar Modern Deltas begins in Baton Rouge and ends in New Orleans, Louisiana in September 2006.

The article presents a calendar of short courses, seminars and tours related to the field of petroleum geology, in the U.S. in 2006. The Winter Education Conference will be held on February 6-10. The course, Practical Salt Tectonics will be held on June 26-28. The short course, Basic Well Log Analysis will be held on August 15-18.

Presents a calendar of courses and seminars on geoscience from July to October 2004. Basic Well Log Analysis; Pore Pressure Prediction; Practical Salt Tectonics.

Presents a list of the seminar schedules in the U.S. about geology in 2003. Well Log Analysis and Formation Evaluation; Practical Salt Tectonics; Controls on Porosity, Distribution in Carbonate Reservoirs.