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The geological formation of the Muschelkalk is widespread in the center of the North German Basin (NGB) and is increasingly attracting interest for application of geothermal energy extraction or high-temperature aquifer thermal energy storage (HT-ATES). This study investigates the Middle Triassic "Rüdersdorfer Schaumkalk", which was the former injection horizon of the natural gas storage facility in Berlin, Germany. For the first time, detailed chemical and microbiological analyses of formation water of this Lower Muschelkalk limestone formation were conducted and hydrogeochemically characterized. In addition, a hydrogeochemical model was developed to quantify the potential reactions during HT-ATES focusing on calcite dissolution and precipitation. The main objectives of this study are: (1) to determine the origin of the water from the three wells targeting the Muschelkalk aquifer, (2) to understand changes in hydrochemistry after system operation, and (3) to evaluate the long-term sustainability of a potential HT-ATES system with increasing temperature. The target formation is encountered by several wells at about 525 m below the surface with an average thickness of 30 m. Two hydraulic lifting tests including physical, chemical, and microbial groundwater as well as gas monitoring were carried out. In addition, several downhole samples of formation fluid were collected from the aquifer at in situ pressure and temperature conditions. Fluid analysis of the saline formation water indicate a seawater origin within the Muschelkalk with subsequent evaporation and various water–rock interactions with anhydrite/gypsum, dolomite, and calcite. With a salinity of 130 g/L, dominated by Na–Cl, a slightly acidic pH between 6 and 7, and a low gas content of 3%, the formation water fits to other saline deep formation waters of the NGB. Gas concentrations and microbial communities like sulfate-reducing bacteria and methanogenic archaea in the produced water indicate several geochemical alterations and microbial processes like corrosion and the forming of biogenic methane. Geochemical simulations of calcite equilibrium over 10 HT-ATES cycles indicated a pronounced propensity for calcite precipitation up to 31 mg/kgw, within the heat exchanger. At the same time, these models predicted a significant potential for calcite dissolution, with rates up to 21 mg/kgw, in both the cold and hot reservoirs. The results from the carbonate aquifer characterized in this study can be transferred to other sites in the NGB affected by salt tectonics and have provided information on the microbiological-chemical processes to be expected during the initial use of old wells. [ABSTRACT FROM AUTHOR]

Areas of the seafloor enriched with seeping fluids host unique chemosynthetic communities, and their interactions not only linked to the presence of oil and gas resources, but directly impact global geochemical cycles. These ecosystems can be found in diverse geological settings, spanning from passive to active continental margins, and encompass environments such as mid-ocean ridges, seamounts, cold brine lakes, mud volcanoes, and carbonate pinnacles. This review aims to examine seep environments in the Western Atlantic, the Caribbean, and Colombia, with a focus on understanding: I) their nature and origin, Itheir associated seabed characteristics, III) the biological communities directly connected to them, and IV) the chemistry and flow of the emitted fluids. The review identifies the close relationship of cold seeps to various geomorphological features, including linear diapir systems, salt diapirs resulting from salt tectonics, regions of mud volcanism, and compact seafloor mounds likely associated with buried mud diapirs. However, existing data on the fauna within these environments predominantly focus on megafauna, such as vestimentiferan tubeworms (Annelida), mussels, and vesicomyid bivalves (Mollusca), overlooking the crucial role of communities of small organisms, including fungi or macrofauna. This review highlights the absence of a consistent consensus among researchers regarding the factors controlling fauna distribution and presence in seep environments. Various authors have put forth divergent factors that influence seep community structures, with some emphasizing water depth, others the geological environment, and some the relationship with geomorphological conditions and fluid emissions. These findings underscore the need for further research into environmental factors and their roles in the observed distribution, presenting a promising avenue for future investigations. [ABSTRACT FROM AUTHOR]

In the central Tarim Basin, numerous hydrocarbon deposits were found along ultra-deep strike-slip faults, and its evolving progress and formation mechanism are research hotspots. The Paleozoic small-angle X-type strike-slip fault in the Tabei Uplift is the research subject in this article. Based on high-precision three-dimensional seismic data, three structural deformation layers were revealed: the rift system, weak strike-slip deformation and salt tectonics in the deep structural layer (Sinian-Middle Cambrian), the strong strike-slip deformation and karst-dissolution structure in the middle structural layer (Upper Cambrian-Middle Ordovician), and echelon normal faults in the shallow structural layer (Upper Ordovician-Carboniferous). The formation and evolution of strike-slip faults is jointly controlled by the distribution pattern of basement rift and the activities of surrounding orogenic belts, which can be divided into three stages. In the Middle to Late Cambrian, the initial subduction of the Paleo-Asian and Proto-Tethyan oceans precipitated the emergence of two sets of small-angle X-type strike-slip faults, striking NW and NE above the grooves of Precambrian rifts, influenced by local weak compressive stress. Affected by the closure of peripheral paleo-ocean, strike-slip faults deformed considerably in the Middle-Late Ordovician and were reactivated in the Silurian-Carboniferous, forming en-echelon normal faults in the shallow layer. The layered deformation structure of the strike-slip faults significantly affects the accumulation of hydrocarbons. The differential hydrocarbon enrichment of faults in the Tabei Uplift is collectively influenced by the distribution of source rocks and the migration of oil and gas. The topographical features of the Tabei Uplift, along with the distribution of strike-slip faults across tectonic units, have rendered the NE direction the preferential pathway for hydrocarbon migration. Additionally, impacted by the development of en echelon faults, the NE-trending faults offer superior conditions for hydrocarbon preservation and charging condition, compared to the NW-trending faults. [ABSTRACT FROM AUTHOR]

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The Global Navigation Satellite System (GNSS) has emerged as a practical and effective technique for studying slow and steady geodynamic movements, enabling continuous monitoring and precise quantification of deformation over different timescales. In Morocco, a network of GNSS stations has been established, offering valuable insights into tectonic processes. This paper focuses on investigating the geodynamic motion of the northwest Moroccan Atlantic Margin. By utilizing GNSS data, subsidence rates and horizontal velocity fields were determined for the first time, providing valuable information for oil and gas exploration activities. The study reveals an active uplift rate of 1 mm/year and a westward horizontal motion of 2.04 mm/year in the Essaouira segment. The paper presents a case study of the Essaouira–Agadir basin (EAB) onshore segment and investigates the anomalous displacement observed in this region compared to other coastal GNSS stations. Possible explanations for the observed movements include local processes such as salt tectonics and regional northwest–southeast compression related to Africa–Eurasia convergence. We suggest that the anomalous movement detected in this work is due to the regional northwest–southeast compression related to Africa–Eurasia convergence imparting an extrusion of the EAB to the west. This research contributes to a better understanding of the geodynamics in the northwest Moroccan Atlantic margin, thereby providing valuable insights for ongoing efforts in oil and gas exploration. Furthermore, it indicates the continued activity of the Agadir fault, which would exhibit a sinistral wrench movement, thus posing a threat to the city of Agadir and its inhabitants. [ABSTRACT FROM AUTHOR]

Distribution of the Triassic succession in the North Sea is poorly understood because of structural complexities associated with halokinesis and limited stratigraphic control. This study uses a seismic and well-based dataset to improve understanding of development of the Triassic succession in the Ula Field Area, in the Norwegian North Sea. Core interpretation revealed a fluvial-dominated depositional environment in the Ula Field Area. Palynological studies allowed dating of cored intervals, revealing Ladinian and Carnian sections, time-equivalent to the Julius and Joanne members of the Skagerrak Formation. Well-log interpretation provided insight into the intra-Triassic stratigraphy of the Ula Field Area. A section considered to be equivalent to and extending from the Smith Bank Formation to the Jonathan Member of the Skagerrak Formation was interpreted and correlated across the area. In the proposed correlation, the Julius Member thins towards the Ula Field Area and is replaced by a time equivalent sandstone unit. The Jonathan Member displays a sandier composition compared to the equivalent section in the UK sector. Seismic facies-based interpretation of Triassic stratigraphy within salt minibasins allowed recognition and mapping of intra-Triassic units and showed that mudstone members thin towards the NE. Interpreted internal geometries within minibasins allowed determination of the timing of halokinesis. Integration of different datasets allowed palaeogeographic reconstructions for the Anisian, early Ladinian, Carnian and Norian to be constructed. To conclude, the distribution of stacked fluvial channel deposits indicates that they occur both within minibasins and across salt highs such that ongoing halokinesis had no topographic expression and that channels were free to migrate across the area. [ABSTRACT FROM AUTHOR]

Polyphase fault evolution through reactivation is a globally observed phenomenon on passive margins. These structures play a crucial role in petroleum systems, offer vital constraints on rift and passive margin kinematics, and, in certain instances, serve as global markers for far-field stresses. Despite the significance of reactivated faults, understanding their kinematic evolution, existence, extent, and interactions within fault populations is often limited. This underscores the need for comprehensive investigations, including considerations of halokinesis in this process. This study presents a structural interpretation of a relay ramp identified in the Penobscot 3D seismic reflection survey offshore Nova Scotia, Canada. The ramp is characterized by two major SSE-dipping faults accompanied by smaller antithetic and synthetic normal faults with a general ENE-WSW strike. The two major faults exhibit evidence of reverse deformation in their lower sections, transitioning to normal offsets in their upper portions. Smaller faults predominantly affect younger strata without evidence of reactivation. Fault throw analysis indicates coupled movement on the main faults during both reverse and normal deformation intervals. Structural analysis suggests that these structures initially formed as reverse faults due to halokinesis and were subsequently reactivated during oceanward salt migration. The timing of Atlantic margin halokinesis aligns broadly with previously documented large-scale kinematic reorganization periods, suggesting similar kinematic events triggered salt movements in the Penobscot area. The observed kinematic dichotomy at depth is crucial, highlighting the potential oversight of polyphase deformation in areas where seismic data only captures near-surface structures. Recognising salt's role in kinematic reactivation is vital, explaining inversion phenomena and generating economically important trapping structures globally. This study implies that reactivation of structures in passive margins may be more widespread than previously acknowledged, particularly if seismic data only captures upper portions of structures. [ABSTRACT FROM AUTHOR]

Triassic evaporites represent the regional décollement of the Pyrenees and form two salt provinces north and south of the South Pyrenean Central Salient (SPCS). We present an updated Bouguer and residual Bouguer anomaly map built upon the homogenization of available gravity data of the SPCS together with four new and representative cross‐sections, constrained by geological data acquired in the field, seismic, well, and gravity data (gravity forward modeling). Gravity anomaly maps and cross‐sections are used to characterize the present‐day uneven distribution of Triassic evaporites. Outcropping Triassic evaporites is not necessarily associated with an underlying evaporite accumulation and the absence of it at surface does not involves its non‐existence at depth. Northwest of the salient, a major accumulation of Triassic evaporites floors a thick syn‐orogenic Upper Cretaceous basin. South of it, Triassic rocks core salt‐detached anticlines related to the Pyrenean orogeny. Along the southernmost (and youngest) thrust sheet of the salient, diapirs, and evaporite accumulations are associated with a salt‐inflated area. Plain Language Summary: Gravity depends on the density of the rocks under our feet. In the South Pyrenean Central Salient (SPCS), an accurate measurement of gravity allows us to recognize gravity anomalies related to low density rocks, such as the Middle‐Upper Triassic evaporites, and map their distribution. Among sedimentary rocks, evaporites have a particular behavior when deformed under geological forces: they flow. This characteristic determines a particular deformation style of the mountains. Characterize the present‐day distribution of Triassic evaporites helps to reconstruct the geological history of the SPCS. Despite the apparent asymmetry of the salient, Triassic evaporites are unevenly distributed and specially accumulated to the northwest and southwest conforming evaporite inflated areas. Key Points: Gravity anomalies help to assess the distribution of Triassic evaporites in the South Central Pyrenean SalientSeismically and gravity‐constrained sections permit a further interpretation of gravity anomaliesInflated salt occurs mainly to the northwest and southeast of the salient, along the northernmost and southernmost thrust sheets [ABSTRACT FROM AUTHOR]

Identification of the processes producing soft‐sediment deformation structures, common in siliciclastic deposits and less abundant in carbonate successions, is complex, because different processes may produce similar structures. Thus, interpreting the origin of these structures may be challenging: it requires both a detailed sedimentological study, and the knowledge of the depositional environment and stratigraphic evolution, in order to provide hints to identify the processes affecting sediments after deposition. Among the potential causes of the formation of soft‐sediment deformation structures, seismic shock is one of the possibilities, but their origin could be also related to other triggering mechanisms, such as volcanic activity, sediment loading, salt tectonics, fluid expulsion, meteorite impacts and mass movements. Although it is a plausible option, the interpretation of these structures as 'seismites' is not obvious: it must be supported by different lines of evidence, considering that the correct interpretation of soft‐sediment deformation structures as a consequence of seismic shocks acquires important implications in palaeoseismology studies. The occurrence of diverse soft‐sediment deformation structures in a fault‐controlled basin (i.e. in a geological setting characterized by syndepositional tectonics) preserved in different subenvironments of a Norian carbonate system in the Southern Alps of Italy provides the chance to characterize different types of soft‐sediment deformation structures along a platform‐to‐basin depositional profile. Presence of pseudonodules in basinal resedimented limestone, sedimentary dykes and clinostratified breccias with unlithified clasts in slope settings and liquefaction of inner platform facies at the platform top testify to an origin compatible with multiple seismic shocks, repetitively affecting the same stratigraphic intervals. The diverse types of soft‐sediment deformation structures in the studied carbonate system provide a rich catalogue of structures related to seismic shocks, representing a possible reference for other similar settings. [ABSTRACT FROM AUTHOR]

Due to the considerable depth of the salt layers and the lack of calibration by exploratory drilling, the interpretation of the Middle and Lower Cambrian salt formations in the central Tarim Basin poses a challenge. In this paper, we apply the coupling and decoupling deformation theory in salt tectonics to analyze the No.7 fault mapped in the seismic datasets by the response characteristics of the Middle and Lower Cambrian layers. By quantifying the stratigraphic framework of the Middle and Lower Cambrian strata, we define the position of the salt layer with the seismic data. Structural decoupling is observed in the Middle and Lower Cambrian sequences in the Shuntuoguole Low Uplift, while deformation coupling is observed in these two sequences in the Shaya Uplift. [ABSTRACT FROM AUTHOR]

In order to better constrain the structural evolution of the North–South Axis (NOSA) running through central Tunisia, a multidisciplinary approach based on geological mapping, field observations and paleostress analysis was used. The geological study of the middle part of the NOSA including the Gadoum, Akrouta, Sidi Khalif, Khechem El Kaleb and Faïd structures, showed the predominance of N–S and E–W fault sets. Movement on the faults of this fault network caused the formation of depositional areas and the collapsed and tilting of fault bounded blocks located in the Southern part of the Gadoum–Akrouta sector. The Gadoum and Akrouta Jebels formed as a result of slip and rotation on a single N–S trending listric fault in the Cenomanian during which time reactivation of both the N–S and E–W fault sets occurred. During Coniacian–Santonian times, when the Aleg Formation was being deposited, the study area was affected by a transtensive regime. This regime led to the division of the area into blocks (e.g. , the Gadoum–Akrouta block and the Wadi El Abiod Syncline) and this resulted in the Aleg Formation being deposited with variable thicknesses. During the Campanian–Early Maastrichtian, a N–S transpressive regime was established, and this regime, coupled with the salt tectonics, resulted in the formation of an angular unconformity, subsidence inversion and lateral thickness variations of the Abiod Formation. During the Early Eocene, an E–W fault network affected the sedimentary basin. These faults, arranged in steps, generated accommodation spaces for sediments which increase in thickness along the North–South Axis. [ABSTRACT FROM AUTHOR]

Areas of the seafloor enriched with seeping fluids host unique chemosynthetic communities, and their interactions not only linked to the presence of oil and gas resources, but directly impact global geochemical cycles. These ecosystems can be found in diverse geological settings, spanning from passive to active continental margins, and encompass environments such as mid-ocean ridges, seamounts, cold brine lakes, mud volcanoes, and carbonate pinnacles. This review aims to examine seep environments in the Western Atlantic, the Caribbean, and Colombia, with a focus on understanding: I) their nature and origin, Itheir associated seabed characteristics, III) the biological communities directly connected to them, and IV) the chemistry and flow of the emitted fluids. The review identifies the close relationship of cold seeps to various geomorphological features, including linear diapir systems, salt diapirs resulting from salt tectonics, regions of mud volcanism, and compact seafloor mounds likely associated with buried mud diapirs. However, existing data on the fauna within these environments predominantly focus on megafauna, such as vestimentiferan tubeworms (Annelida), mussels, and vesicomyid bivalves (Mollusca), overlooking the crucial role of communities of small organisms, including fungi or macrofauna. This review highlights the absence of a consistent consensus among researchers regarding the factors controlling fauna distribution and presence in seep environments. Various authors have put forth divergent factors that influence seep community structures, with some emphasizing water depth, others the geological environment, and some the relationship with geomorphological conditions and fluid emissions. These findings underscore the need for further research into environmental factors and their roles in the observed distribution, presenting a promising avenue for future investigations.

One of the most remarkable features of the central Northern Calcareous Alps (Eastern Alps, Austria) is the widespread presence of Upper Triassic deep-water carbonates (the Hallstatt facies) and Permo-Triassic evaporites resting on deep-water Middle Jurassic strata and their underlying Upper Triassic shallow-water carbonate platform successions. The Hallstatt facies and accompanying evaporites have been classically interpreted to originate either from a location south of the time-equivalent carbonate platforms, or to have been deposited in deeper water seaways within the broad platform domain. To date, this dispute has been addressed mostly through the analysis of Triassic and Jurassic facies distribution in map view, which, however, is subject to some degree of ambiguity and subjectivity. In this contribution we present, for the first time, sequentially restored regional cross-sections through the central Northern Calcareous Alps to understand the implications of the contrasting paleogeographic models. We present (a) an interpretation based on a highly allochthonous origin of the Triassic deep-water units and (b) an interpretation based on their relative autochthony in which we incorporate the potential influence of salt tectonics in the central NCA. The restored cross-sections provide a framework within which the alternative scenarios and their paleogeographic implications can be better understood. Through this analysis we propose that salt tectonics in the central NCA can provide a valid explanation for apparent inconsistencies in the relative autochthony scenario and thus constitutes a reasonable alternative to the currently accepted allochthony scenario. [ABSTRACT FROM AUTHOR]

This paper presents a sequentially restored cross-section of the Organyà and Montsec minibasins based on geological mapping, new field observations and available borehole data. The main objective was to describe the geometry and evolution of both basins in terms of salt tectonics and minibasin mobility. To this end, a comprehensive palaeomagnetic database has been used to constrain vertical-axis rotations potentially related to minibasin translation and pivoting. The Organyà minibasin constitutes an asymmetric depocentre formed during the Upper Jurassic-Lower Cretaceous by translation above a southerly inclined salt layer. Salt evacuation and minibasin touchdown induced salt accumulation on the northern side of the basin that culminated in the development of the major Santa Fe unconformity during the late Albian--early Cenomanian. Indicative of salt quiescence is the following isopachous Cenomanian to lower Santonian sequence Salt tectonics resumed during the late Santonian--Palaeocene, with the Montsec minibasin downbuilding coinciding with the onset of Pyrenean convergence. Changes of the base-salt topography reflects regional-scale geodynamic processes. The acceleration of crustal thinning in the North Pyrenean zone during the late Albian-early Cenomanian favoured uplift in the Axial Zone, increasing slope and triggering salt mobilization in the Southern Pyrenees. Likewise, the onset of contraction renewed the downslope gliding of the Organyà and Montsec minbasins, and supports the idea that the early stages of basin inversion were governed by gravity tectonics. The kinematic reconstruction suggests that the more that 30° counterclockwise vertical axis rotation records pivoting during the suprasalt translation of the Organyà minibasin rather than solely the Iberian microplate rotation. [ABSTRACT FROM AUTHOR]

This paper presents the results of seismostratigraphic interpretation of the Upper Cretaceous sedimentary succession preserved within two synclines flanking the Szamotuły diapir in northwestern Poland. This succession is characterized by a complex Santonian--Campanian internal geometry characteristic of contourites -- that is, deposits formed by contour (bottom) currents. The aim of the present paper is to document these contourites using 2D seismic reflection profiles calibrated by the Obrzycko 1 well. The contourite drifts in the immediate vicinity of the Szamotuły structure exhibit elongated mounded shapes, with adjacent concave moats. At greater distances from the diapir, gradual aggradational patterns are observed. The formation of these Santonian--Campanian contourites was associated with growth of the Szamotuły diapir during regional compression and Polish Basin inversion. These contour currents and associated contourites formed an integral part of a regional axial depositional system developed within the flanks of the Mid-Polish Anticlinorium. Furthermore, this paper discusses the potential role of contourites as palaeomorphological indicators of palaeoslopes in varied geodynamics settings, such as inverting sedimentary basins, as opposed to the passive margins upon which they have been most commonly documented. [ABSTRACT FROM AUTHOR]

This article examines the geotectonic and sedimentary features of the Upper Devonian–Carboniferous–Permian deposits of the North Caspian basin, represented by deposits of marine Paleozoic-isolated carbonate platforms formed during the subsidence of the basement on the passive continental margin. The top is covered by thick salt-bearing Kungurian deposits from the end of the Early Permian epoch. The formation of carbonate platforms is associated with a major tectonic restructuring of the basin at the turn of the Caledonian and Hercynian eras, when the Paleo-Tethys Ocean was formed and isolated carbonate islands began to grow in an open marine environment. The central part of the depression experienced a long and gradual subsidence that spanned the entire Paleozoic era and the beginning of the Mesozoic era. In the south and east, from the Devonian to the Permian periods, barriers were formed in the form of island carbonate massifs that separated the North Caspian basin from the Paleo-Tethys Ocean. During the formation of the salt-bearing basin, these barriers limited water exchange and ensured a one-way influx of sea water from the open ocean. As a result, at the end of the Permian period, thicker salts accumulated; however, during the collision of the continental massifs, an invasion of many kilometers of redbeds occurred. They initially stopped salt accumulation; however, gradually, in the north of the Caspian Sea during Roadian times, the salt accumulation continued. The post-Roadian time is associated with the influx of large quantities of redbed sediments, which caused gravitational instability in the underlying salt, and salt tectonics began with the formation of domal structures. [ABSTRACT FROM AUTHOR]

The Ionian Zone (IZ) is one of the key elements of the fold and thrust belt (FTB) of the Albanian and Hellenides orogen and contains large outcrops of Triassic evaporites. The IZ consists of various thrust sheets with a general westward vergence, stacking over the Apulian and Pre‐Apulian zones, and repeating a thick carbonate sequence of Upper Triassic to Eocene age. Thrusting becomes younger toward the west with a piggyback sequence, starting during the latest Oligocene Epoch in the Internal Ionian and ending in the Pliocene in the External Ionian. We have studied the IZ in southern Albania and northwestern Greece using field observations and borehole data and by fully interpreting a recently acquired 2D seismic data set. Our objectives are to establish the geometry and nature of the contacts associated with the major Triassic outcrops, to unravel precursor salt diapirs, and to assess their role during the Alpine contraction. Salt structures include gentle salt pillows, isolated salt plugs and diapirs, thrust welds, and salt walls. Combining these observations with experimental modeling results, we show how these structures control the geometry and kinematics of the Alpine thrusts or the location and kinematics of recent strike‐slip faults. Salt minibasins have also been identified, demonstrating salt mobility conditioned Mesozoic sedimentation in the Ionian Basin. The use of salt‐tectonics principles to evaluate the structural style and evolution of the IZ FTB also opens new directions for interpreting the subsurface structure and evolution of the region. Key Points: The Ionian Zone in Greece and Albania is studied with surface geology, borehole data, and the interpretation of new seismic profilesTriassic salt pillows, isolated thick diapirs, and elongated salt walls condition the style of this Alpine fold and thrust beltThe role of pre‐existing diapirs is compared with experimental models [ABSTRACT FROM AUTHOR]

We present the first sequential structural restoration with flexural backstripping of the Gulf of Mexico US‐Mexico conjugate margin salt basin. We construct four large‐scale (100s of km) balanced, sequential structural restorations to investigate spatio‐temporal patterns of subsidence, geometry of the original salt basin, feedbacks between post‐salt structural and stratigraphic evolution, paleo‐bathymetry, and crustal configurations. The restorations are based on interpretations of 2D and 3D seismic data, and include sequential sedimentary decompaction, flexural isostatic backstripping, and thermal isostatic corrections. The spatially variable crustal thinning factor is directly measured from seismic data, and lithologic parameters are determined by well penetrations. We present a model for the original salt basin and discuss evidence for and implications of a deep water salt basin setting for the GoM. Our analysis suggests a salt basin that contained ∼1–2 km thick salt in a basin 175–390 km across with ∼1 km of bathymetry after salt deposition. The base of salt is mostly smooth with <1 km of local relief in the form of normal faults that disrupt a pre‐salt sedimentary section. We find that supra‐salt extension and shortening are not balanced, with measurable extension exceeding shortening by 18–30 km on each cross‐section. Our subsidence analysis reveals anomalous subsidence totaling 1–2 km during Late Jurassic and Early Cretaceous times that may reflect dynamic topography or depth‐dependent thinning. We offer an interpretation of crustal breakup invoking pre‐salt clastic sedimentation, salt deposition in a deep water syn‐thinning basin, and post‐salt lower‐crustal exhumation. Plain Language Summary: The Gulf of Mexico is a large basin that formed over 200 million years ago due to tectonically driven extension of a supercontinent. Early in its formation it accumulated thick salt deposits. Due to that salt and the later deposition of several kilometers of sedimentary rock that conceal the deep geology, it is difficult to know exactly how extension started and progressed. This study uses new 2D and 3D seismic data that images the deep geology corresponding to that early extension. We sequentially remove each rock layer to reconstruct what the margin looked like in the Mesozoic. By systematically moving back in time we are able to reconstruct the changing geometry, deformation, and bathymetry of the Gulf of Mexico. Our results reveal periods of time when the bathymetry was influenced by unknown factors, which we posit reflects mantle forces. Key Points: We present sequential structural restorations with flexural backstripping of the post‐rift eastern GoM conjugate US‐MX margin from Mesozoic to presentWe interpret the geometry and bathymetry of the restored Mesozoic salt basinOur analysis indicates significant and widespread Mesozoic anomalous subsidence [ABSTRACT FROM AUTHOR]

Continental rifted margins can be associated with widespread and thick salt deposits, which are often formed during the final stages of rifting, prior to breakup. These salt‐bearing margins are typically characterized by pronounced post‐rift salt tectonics with variable and complex structural styles and evolution. We use a lithosphere‐scale geodynamic numerical model to investigate the role of varying post‐rift sediment fluxes and progradation rates on rifted margin salt tectonics. We focus on a single, intermediate, rifted margin type and salt basin geometry to explore scenarios with different: (i) constant and (ii) time‐varying post‐salt sediment fluxes. We demonstrate that these promote significant contrasts in the style and magnitude of salt tectonics in the proximal, transitional and distal margin domains. The differences are primarily controlled by the relationship between the rates of sediment progradation (Vprog) and salt flow (Vs). When Vprog > Vs, the salt is rapidly buried and both vertical and lateral salt flow are suppressed across the entire margin. When Vprog < Vs, the salt flows vertically and seaward faster than sediments prograde producing major diapirism in the proximal domain and major distal nappe advance, but only moderate overburden extension and distal diapirism. When Vprog ~ Vs, there is moderate proximal diapirism and distal nappe advance, but major updip extension and downdip shortening, which produces major distal diapirism. Modelling results are comparable to various natural systems and help improve our understanding of the controls and dynamics of salt tectonics along salt‐bearing rifted margins. [ABSTRACT FROM AUTHOR]

Salt‐bearing rifted margins comprise some of the most structurally complex and economically important sedimentary basin settings such as the South Atlantic and the Gulf of Mexico salt basins. They are also involved with some of the largest uncertainties regarding the crustal and syn‐rift basin architecture and supra‐salt tectonic evolution, as well as the link between rifted margin architecture with salt deposition and post‐rift gravity‐driven salt tectonics. We thus conduct a margin‐scale study along nearly the entire West African salt basin, from South Gabon to Namibe, combining a vast data set of 2D and 3D seismic and well data with gravimetric and magnetic data to analyse its along‐strike rift and salt tectonic structural variability. We construct regional structural and thickness maps of key salt and post‐salt intervals to depict the history of individual margin segments and to investigate (1) how rifting and rifted margin architecture influences post‐rift salt tectonics evolution, (2) how these vary through time and space and (3) what are the controls between their different salt tectonic styles. We show that rifting and rift structures controlled the salt basin geometry, thickness and base‐salt relief in different ways for the different margin segments, and drastically influenced their post‐rift salt tectonic evolution. Differences in post‐salt sediment supply and continental uplift also had a role in their salt tectonic evolution. The results also have general implications to understand the interplay between rifted margin architecture with post‐rift salt tectonics for salt‐bearing rifted margins. [ABSTRACT FROM AUTHOR]

Salt structures can be used as an archive for tectonic and depositional processes as all salt structures respond distinctively. Few salt tectonic studies have investigated the evolution of multi‐stage salt structures, nevertheless, no previous study had systematically identified, mapped, nor classified, the evolution of multi‐stage salt structures in a regional study. Decades of hydrocarbon exploration and the heavily dense 3D seismic data available, make the Southern North Sea one of the best natural laboratories to investigate the evolution of salt structures. The Southern North Sea salt basin is a Late Permian Zechstein salt mega‐basin containing a myriad of salt structures. The complex tectonic evolution of the Southern North Sea created diverse Mesozoic structural sub‐basins with different tectonostratigraphic evolutions. We defined a nomenclature, linked to the mega‐stratigraphic sequences, for the classification of salt structures. We used a Two‐Way‐Travel‐Time 3D seismic reflection dataset and time‐thickness variations around salt structures to systematically analyse the evolution of salt structures across the diverse structural sub‐basins of the Southern North Sea. Multi‐stage salt diapirs were triggered halokinetically in the Early Triassic and are linked to regional palaeo‐depocentres controlled by the sub‐Zechstein structural configuration. Multi‐stage salt diapirs in the different sub‐basins evolved through three different regional phases and up to five distinctive local stages. The most complex salt diapirs developed in the Central Graben, Sole Pit High and Silver Pit Basin, where multi‐stage salt diapirs showed 4–5 local stages of salt diapirism. The multi‐stage evolution of salt structures should be thoroughly investigated to reduce risks and uncertainties in the energy sector and net zero projects, such as in carbon capturing and storage projects, and energy storage in man‐made salt caverns. [ABSTRACT FROM AUTHOR]

The article presents the results of DSS seismic surveys in the Persian Gulf. Bottom analog-type seismographs and seismic airgun sources were used in the studies. The bottom seismographs were moored and shooting was carried out according to three regional profiles with a length from 100 to 250 km. The main result of these studies was a velocity–depth model of the sedimentary cover and Earth's crust up to the Moho boundary, which was revealed at a depth of about 43 km in the water area. Given that the thickness of the upper crust is only 4–5 km and based on the velocity characteristics of the remaining layers, the type of crust can be attributed to the subcontinental Archean type. This situation (complete absence or drowning of the upper layer of the Earth's crust) is typical of the waters closest to the Persian Gulf: the Black, Caspian, Mediterranean, and Red seas. A structure was found in the Earth's crust of the studied area, which may be a brachyanticline with an isometric dome-shaped shape, which corresponds to the platform-type folding in the areas of salt dome tectonics. No faults have been found in the crust of the water area of the Persian Gulf adjacent to the Bushehr Peninsula. [ABSTRACT FROM AUTHOR]

Currently, the interpretation scheme for strike slip faults in the central Tarim Basin does not typically take into account the depth of tear faults. This paper specifically explores this aspect, focusing on two tear faults (Nos. 4 and 7) to examine the thick-skinned and thin-skinned systems in the area. By utilizing high-resolution seismic data, we discovered that No. 4 Fault is a thick-skinned tear fault whereas No. 7 Fault is a thin-skinned tear fault. Additionally, we have calculated the strata shortening data for both Nos. 4 and 7 Faults to further our understanding of these systems. For No. 4 Fault, we observed shortening differences between the western and eastern sections in both the supra- and sub-salt strata, whereas for No. 7 Fault, we observed shortening differences only in the supra-salt strata. We demonstrated that under the action of thrusting, a tear fault could penetrate the salt layer if there is a shortening difference in the different positions of the sub-salt strata. A lack of shortening difference in the sub-salt strata implies that a tear fault should be thin-skinned which cannot penetrate the salt layer, even though the sub-salt strata may be deformed during thrusting.

Identifying regional structures in areas of limited exposure and sparse subsurface information can be challenging. Small-scale observations must be collected and combined to develop a stratigraphic-structural concept and eventually a sound regional geologic model. In this contribution, we review the local stratigraphic evidence for the Eichsfeld-Altmark Swell (EAS) in Central Germany and how it adds up to a regional picture. The EAS is commonly interpreted to be an approximately NNE--SSW-trending Permo-Triassic intrabasinal high, expressed by reduced thickness, facies changes and unconformities in Late Carboniferous to Late Triassic strata. In fact, an area of hiatuses or reduced thickness, often accompanied by facies changes, can be identified from Rotliegend to Keuper times. The uplifting or less subsiding EAS is accompanied by varying depocentres trending parallel to it, particularly in the west. One of these depocentres, the Jurassic Gifhorn Trough, suggests that also activity of the EAS may have continued into Jurassic time. Especially in Buntsandstein and Keuper time, the EAS appears as a 50 km wide, very gently eastward tilted block or rift shoulder bordered in the west by the Braunschweig-Gifhorn Fault Zone (BGFZ). However, the exact links between basement faulting, regional upwarping/tilting and cover structures detached along Zechstein evaporites remain elusive. Regional thickness reductions associated with the large EAS contrast with local, in part stronger thickness reductions associated with structures of the BGFZ and accompanying salt tectonics. [ABSTRACT FROM AUTHOR]

Sedimentary sequences containing evaporitic levels exhibit complex three-dimensional structures due to halokinetic movements known as salt tectonics. In the Anticlinal de Zipaquirá, located in the Cordillera Oriental of Colombia, saline levels are reported within the Lower Cretaceous units. This study conducted a structural analysis of the evolution of the Anticlinal de Zipaquirá, based on analogue models that simulate the relationship between salt tectonics and the transverse zones that bound and segment this structure. The models were constructed on a sandbox-type deformation table, maintaining a constant displacement velocity. The models simulate basement anisotropies using a rigid wooden block consisting of two frontal ramps inclined at 30° connected by a lateral ramp. Adjacent to this block, a layer of non-newtonian fluid and variable-colored fine quartz sand layers were arranged. Three configurations were implemented with different distributions of the non-newtonian fluid layer: A) thin continuous, B) discontinuous, and C) thick continuous. At least 15 experiments were conducted for each configuration. The results of the analogue modeling showed that the salt body in the core of the anticline is cut by reverse faults, forming a parallel salt sheet structure to the stratification. The observed structures, such as salt pillows, salt glaciers, salt sheets, and salt tongues, indicate compressive structural styles of intermediate to high maturity. The discontinuous model proved to be the most coherent since the lateral ramp did not exhibit evaporitic levels, aligning with observations in nature. The Neusa transverse Fault was represented by the lateral ramp in the model, explaining the localization of saline levels in the southern zone of the Anticlinal de Zipaquirá. Finally, the evolution of the models revealed clockwise rotations near the lateral ramp, consistent with the reported patterns of clockwise rotations in the axial zone of the Cordillera Oriental. [ABSTRACT FROM AUTHOR]

The formation and structural evolution of complex intracontinental basins, like the North German Basin, mark fundamental earth processes. Understanding these is not only essential to basic research but also of socioeconomic importance because of the multitude of resources, potential hazards, and subsurface use capability in such basins. As part of the Central European Basin System, major subsidence and structural differentiation affected the Baltic sector of the North German Basin in Permian‐to‐Jurassic times. A dense network of high‐resolution 2D seismic data together with nearby wells allow the creation of regional maps with refined stratigraphic subdivision of unprecedented spatial resolution covering the bays of Kiel and Mecklenburg (Baltic Sea). Cross sections along the basin margin allow reconstruction of the structural evolution of the Zechstein salt and its overburden. At the northern basin margin, near the Kegnaes Diapir, thinning of the Buntsandstein and divergent reflectors indicate Early Triassic faulting and salt movement. In the Late Triassic, tectonic activity increased as expressed by the onset of salt movement in the north‐eastern Glückstadt Graben, major growth of the Kegnaes Diapir and faulting at the north‐eastern basin margin during deposition of the Keuper (Erfurt, Grabfeld, Stuttgart and Weser formations). At the north‐eastern basin margin, we interpret the accumulation of Keuper and Jurassic deposits as an infill of a local sub‐basin bordered by the Werre Fault Zone and Agricola Fault System. Between the Glückstadt Graben and the north‐eastern basin margin, the Eastholstein–Mecklenburg Block formed a more stable area, where salt movement first began during the latest Triassic. In the peripheral part of the basin, salt movement was triggered by thin‐skinned extension associated with thick‐skinned faulting within the axial parts of major graben systems. Indications for gravity gliding are absent. Reactive diapirism is restricted to the basin margin, where reduced overburden thickness and Late Triassic erosion allowed diapiric breakthrough. [ABSTRACT FROM AUTHOR]

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. Key Points: Structural mapping resulted in the first recognition of pre‐orogenic salt structures in the Western CarpathiansTriassic syn‐sedimentary evaporite deformation led to minibasin formation, variations in formation thickness and facies differentiationThe results provide guidelines on how to distinguish inherited salt structures from shortening‐related structures in fold‐and‐thrust belts [ABSTRACT FROM AUTHOR]

Reinterpretation of the Organyà Basin, based on new detailed field observations and subsurface data, emphasizes the key contribution of Upper Triassic evaporites in the tectono‐sedimentary evolution of the South‐Central Pyrenees. Results are integrated in a 65‐km long restored cross‐section through the Serres Marginals, Montsec and eastern Organyà salt‐related depocenters. The reconstructed part of the Jurassic–Cretaceous northern Iberian salt‐rich rifted margin shows a template characterized by inherited Permo‐Triassic basement normal faults and an initial salt thickness of 0.7 km to the south and 1.5 km to the north. The Organyà Basin is part of the South Pyrenean Diapiric Province, a large system of salt related depocenters and minibasins, that is limited to the north by the more than 120‐km long Senterada salt wall complex separating the supra‐salt and sub‐salt domains in the Southern Pyrenees. Three main stages of diapiric activity are recognized along the northern Iberian margin from Asturias to the Eastern Pyrenees: a Jurassic early salt mobilization; a latest Jurassic–middle Albian main diapiric evolution associated with rifting; and a Campanian–Miocene diapiric reactivation during basin inversion that produced salt welds and thrust welds and translated the salt province some 60 km to the south. Key Points: Reinterpretation of the Organyà Basin indicates occurrence of a large and continuous salt tectonics province in the South‐Central PyreneesLate Jurassic early salt mobilization followed by Early Cretaceous passive diapirism and diapir reactivation from late CampanianThe restored 65 km wide salt‐bearing passive margin indicates asymmetrical Iberia‐Eurasia conjugate margins [ABSTRACT FROM AUTHOR]

The present study examines the imprint of salt tectonics on carbonate depositional patterns of the Ionian zone platform edge to slope transition. The study area is part of an overturned rim syncline adjacent to a salt diapir. The Ionian zone is made up of three distinct stratigraphic sequences (pre-, syn- and post-rift sequences) represented by evaporites and shallow water carbonates at the base that pass gradually to a sequence consisting of pelagic limestones with shale intervals. In the study area, six cross sections were constructed, mainly covering the edge-to-slope overturned succession of Early Cretaceous to Eocene carbonates (post-rift stage) in the northern limb of the syncline. In the measured sections, abrupt changes in sediment texture resulted in the formation of distinct, thick-bedded carbonate layers, identified as packstones to grainstones–floatstones, with abundant fossil fragments, indicating deposition by debrites in a platform slope or slope-toe environment. Planar and ripple cross-lamination also suggest the involvement of turbidity currents in the depositional process. In the upper levels of the Lower Cretaceous carbonates, chert bodies with irregular shapes indicate soft sediment deformation due to instability of the slope triggered by salt intrusion. Internal unconformities identified in the field and in the available seismic data combined with the vertical to overturned dipping of the strata correspond to a basal megaflap configuration. Syn-sedimentary deformation resulted in the accumulation of debritic and turbiditic layers, while the compressional regime established in the area from the Late Cretaceous to Early Eocene enhanced the fracture porosity of carbonates, which could eventually affect the reservoir properties. [ABSTRACT FROM AUTHOR]

By harnessing both hypothetical, synthetic basin and gas hydrate (GH) system models and real‐world models of well‐studied salt diapir‐associated GH sites at Green Canyon (Gulf of Mexico) and Blake Ridge (U.S. Atlantic coast), we propose and demonstrate salt movement (and in particular, diapirism) to be a new mechanism for the recycling of marine GH. At Green Canyon, for example, we show that by considering this newly proposed diapir‐driven recycling mechanism in conjunction with previously proposed lithological control on sandy‐reservoir‐hosted hydrate at the base of the GH stability zone (BGHSZ; ∼bottom‐simulating reflector, BSR), modeled GH saturations match drilling data. Overall, salt diapir movement‐induced GH recycling provides a temperature‐driven mechanism by which GH saturations at the BGHSZ may reach >90 vol. % and by which GH volumes near and free gas volumes beneath the BGHSZ may be increased significantly through time. Interestingly, comparison of salt diapir‐driven recycling and sediment burial‐driven recycling scenarios suggests notably higher rates of recycling via diapir‐driven versus burial‐driven processes. Our results suggest that GH and associated free gas accumulations above salt diapir crests represent particularly attractive targets for unconventional and conventional hydrocarbon resource exploration and for scientific and academic drilling expeditions aimed at exploiting GH systems. Salt basins containing GH systems—including passive margin basins of the Gulf of Mexico, southeastern Brazil, and southwestern Africa—are therefore compelling localities for studying salt‐driven GH recycling and for salt diapir‐associated natural gas exploration. Plain Language Summary: Gas hydrates (GHs) are ice‐like solids widely distributed in permafrost settings and marine sediments of continental margins. Hydrate deposits contain vast amounts of carbon, mostly in the form of entrapped methane, and are therefore critical components of the global carbon cycle. High‐saturation GH accumulations are attractive as potentially extractable energy resources, and the processes resulting in concentrated hydrate deposits are therefore of particular scientific and economic interest. Here, we explore GH recycling, a process by which hydrates pushed below their pressure‐ and temperature‐defined stability zone destabilizes and releases buoyant gas that may be reincorporated into the upward‐shifted zone of hydrate stability, leading to increasingly elevated hydrate saturations. Using computational basin modeling and two‐dimensional forward modeling of both theoretical and real‐world GH systems, we present a new mechanism for GH recycling: the ascent of salt diapirs. Key Points: We demonstrate salt diapir movement and associated thermal changes to be a mechanism for gas hydrate recyclingHydrate at the base of hydrate stability can reach saturations >90 vol. % and trap large free gas accumulations via diapir‐driven recyclingDiapir‐driven recycling helps explain Green Canyon hydrate saturations and implies that salt basins with hydrate are attractive for exploration [ABSTRACT FROM AUTHOR]

Salt tectonics is typically caused by the flow of mobile evaporites in response to post‐depositional gravity gliding and/or differential loading by overburden sediments. This situation is considerably more complex near the margins of salt basins, where carbonate and clastic rocks may be deposited at the same time as and be interbedded with more mobile, evaporitic strata. In these cases, syn‐depositional salt flow may occur due to density differences in the deposited lithologies, although our understanding of this and related processes is relatively poor. We here use 3D seismic reflection and borehole data from the Devil's Hole Horst, West Central Shelf, offshore UK to understand the genesis, geometry, and kinematic evolution of intra‐Zechstein Supergroup (Lopingian) minibasins and their effect on post‐depositional salt deformation. We show that immobile, pinnacle‐to‐barrier‐like, carbonate build‐ups and anhydrite are largely restricted to intra‐basin highs, whereas mobile halite, which flowed to form large diapirs, dominates in the deep basin. At the transition between the intra‐basin highs and the deep basin, a belt of intra‐Zechstein minibasins occurs, forming due to the subsidence of relatively dense anhydrite into underlying halite. Depending on primary halite thickness, these intra‐Zechstein minibasins created topographic lows, dictating where Triassic minibasins subsequently nucleated and down‐built. Our study refines the original depositional model for the Zechstein Supergroup in the Central North Sea, with the results also helping us better understand the style and distribution of syn‐depositional salt flow within other layered evaporitic sequences and the role intra‐salt heterogeneity and related deformation may have in the associated petroleum plays. [ABSTRACT FROM AUTHOR]

High-resolution bathymetric and shallow seismic data along the northeast Red Sea margin reveal a previously disregarded mechanism for carbonate platform drowning at a steepflanked rift basin. At the seafloor, salt extrusions highlight the influence of extensional salt tectonics, with a salt flow from the southern flank of the Al Wajh carbonate platform that likely originates from below. Salt-flow direction, morphology, and kilometer-sized slumps and rotated blocks indicate platform-margin disintegration and rafting of platform blocks toward the southwest. The outlines of several smaller detached or semi-detached carbonate platforms to the south of the main platform can be refitted to the larger platform margin by counter-moving the direction of mass wasting. Several platforms, reaching heights above the seafloor of up to 650 m, are partially or fully submerged in the mesophotic zone and appear to be in danger of drowning. We conclude that the southern outer rim of the Al Wajh platform is breaking apart owing to salt withdrawal, which indicates that carbonate platforms on top of salt sequences grow on mobile ground, leading to platform disintegration, basinward rafts, and the demise of broken-off, smaller pieces of platform. Salt displacement also controls the growth geometries of individual platform rafts, with keep-up reef growth (growth rate equal to sea-level rise) and drowning occurring in close spatial proximity. Therefore, the interplay between salt diapirism and platform growth is not limited to platforms growing on the apexes of diapirs and is more complex than previously thought. [ABSTRACT FROM AUTHOR]

Many works in the last decades underline the role of evaporites, not just as a conditioning factor but as the engine for subsidence and eventually basin inversion. The western Mediterranean alpine ranges are being investigated in this regard because of the presence of discontinuous units of Permian to Triassic evaporites, deposited in the western Tethys basins. This work presents a thorough analysis of two particular structures (Cañada Vellida and Miravete anticlines) in the intraplate Maestrazgo basin (eastern Iberian Chain, Spain) in which evidence to support their reinterpretation as salt‐driven structures have been recently reported. Our analysis includes (i) a comprehensive stratigraphic and structural study of the folds along their entire trace, (ii) the compilation of thickness and distribution of evaporite–bearing and supraevaporite units, paying special attention to changes in the thickness of units in relation to anticlines, and (iii) the study of fault patterns, sometimes in relation to the mechanical stratigraphy. All three aspects are also documented and discussed on a regional scale. The new data and interpretations reported here reinforce the extensional origin of the Late Jurassic–Early Cretaceous basins, and the role of regional extensional tectonics as the responsible for the development of first‐order syn‐sedimentary normal fault zones driving the formation and evolution of sub‐basins. These basins were subsequently inverted and deformed, including the formation of complex, box‐geometry anticlines that, in their turn, controlled deposition in Cenozoic basins. The review of the arguments that support the alternative of salt tectonics for the origin of such anticlines has allowed us to delve into the sedimentary and tectonic evolution of the inverted extensional basins and to propose a specific model for the development of these faulted anticlines. The role of salt levels and other interlayered detachments in the structuring of sedimentary basins and their inversion is also pondered. The observations in the eastern Iberian Chain reported here have implications to assess ongoing reinterpretations in terms of salt tectonics in other alpine basins and ranges of the western Mediterranean. [ABSTRACT FROM AUTHOR]

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Within Eastern Ukraine, in the course of previous studies, neotectonic movements were established, caused by both salt tectonics and Attic (post-Miocene - pre-Pliocene) thrust dislocations of northeastern vergence. They are partially displayed in modern relief. The aim of the study was to reveal the structural results of the interaction of post-Pliocene fold-thrust deformations and modern salt tectonics of Eastern Ukraine. Research methodology. The base of the Cenozoic deposits of Eastern Ukraine was chosen as an indicator surface reflecting both those and other movements. Its initial orientation is horizontal. Deviations from the horizontal reflect the direction and amplitude of deformations. The morphology of this surface was depicted by isolines with a vertical step of 20 m. To build a map of the supporting surface, state geological maps and data from more than 2,100 wells drilled in this area were used. Research results. A map of the shape of the Cenozoic base in tectonic blocks between the Attic thrusts and beyond their development has been constructed. Uplifts of this surface, which are not associated with thrust movements, have been revealed. The dimensions of such uplifts are 8÷30 × 6÷15 km with vertical amplitude of 40 - 100 m or more. The uplifts are usually contoured by ring or arc compensation troughs a few kilometers wide and 20-100 m deep. Some of these uplifts are associated with the known salt domes of the area. Other uplifts do not contain such domes. It is possible that they formed over salt "pillows", which did not have enough salt reserves to form salt diapirs. The area of distribution of such uplifts approximately corresponds to the area of distribution of Devonian salt deposits at a depth of 5-10 km or more. Scientific novelty. Neotectonic uplifts were discovered, similar in shape and size to those caused by salt tectonics, but located outside the areas of distribution of known salt-bearing strata. It is hypothesized that this is related to the older Hercynian overthrusts. The uplifts are located above the hanging blocks of the Hercynian overthrusts in the north and south of the study area. These thrusts were formed on the northern and southern sides of the former Dnieper-Donetsk depression during its destruction by the Hercynian folding. It is possible that the nappes over thrusts the Devonian salt-bearing deposits with metamorphic rocks of the crystalline basement. The decrease in the level of the World Ocean in the Quaternary period further increased the lithostatic load on the salt-bearing strata. This activated the isostatic upwelling of salt and the formation of gently sloping neotectonic uplifts. Practical significance. These results clarify the geological structure of the territory and make it possible to expand the area of hydrocarbon prospecting.

A recent road cut through a Dammam Formation outcrop on the Dammam Dome in Dhahran, Saudi Arabia, exposed an array of open fractures and gypsum-filled veins. The discontinuities were mostly contained within the Saila Shale member and consisted of horizontal, vertical, and inclined extensional fractures, most of which were filled with gypsum. The veins were of varying thickness with the largest exceeding 2.5 inches. Vertical gypsum veins, similar to those encountered at the road cut, were found in adjacent areas. A thin layer of gypsum (about 1 inch) was also observed in the Upper Rus Formation. The open vertical and horizontal fractures, in the Saila and Midra Shale members, were devoid of gypsum fill, and were interpreted to be recent with indications of being triggered by the excavation work. The open fractures and filled veins covered a stretch of about 250 ft. across the road cut that also exposed what was interpreted as a local karst collapse. Horizontally-layered and continuous rocks overlying the collapse indicated that it was a paleo structure. The causal mechanism for fracture formation and subsequent fill was associated with deformations accompanying post-karst collapse. Here, natural fracturing and fluid transport were not synchronous events. Insights from this interpretation offered an explanation for widespread surface structures with major and subtle morphologies on the Dammam Dome. These insights also highlighted the significance of collapse in the modification of the Dammam Dome over a geological timescale. The unstable nature of gypsum, prevalent in Dammam Formation in the Dammam Dome, has potential implications for integrity of anthropogenic structures such as roads and building foundations.

The classic fill‐and‐spill model is widely applied to interpret topographic controls on depositional architecture and facies distributions in slope successions with complicated topography. However, this model implies a constant topographic configuration over the lifespan of a turbidite system. In contrast, the impact on patterns of erosion and deposition above dynamic slopes whose topographic configuration varies spatially over time remains poorly investigated. Here, using high‐resolution 3D seismic reflection data and more than 100 wells from a 40 km long stepped slope system (Campos Basin, offshore Brazil), we document the evolution of a sand‐prone turbidite system active during the Oligocene–Miocene transition. This turbidite system was influenced by vertical and lateral deformation, and we propose a new stratigraphic model to explain the resultant depositional architecture. Two depocentres were identified as steps, with channels on the proximal step, and channel–lobe complexes on the distal step, bounded by sediment bypass‐dominated ramps. Lateral stepping of channels on the proximal step, and oblique stacking of the down‐dip lobe complexes, each cut by through‐going channels, indicate multiple fill‐and‐spill cycles. A persistent north‐east‐ward stepping and thickening on the steps are interpreted to reflect lateral tilting of the seafloor driven by salt tectonics. The dynamic substrate prevented the establishment of a single long‐lived conduit across the proximal step, as recorded in systems with fixed topographic configurations. The filling of through‐going channels with mud at the end of each cycle suggests waxing‐to‐waning sediment supply cycles and periods of sand starvation when the lateral tilting dominated and drove avulsion of the feeder channels towards topographic lows. This study demonstrates that subtle dynamic slope deformation punctuated by discrete sediment supply cycles results in complex stratigraphic patterns with multiple phases, and multiple entry and exit points. Repeated cycles of fill‐and‐spill, tilt‐and‐repeat are likely to be present in other stepped slope systems. [ABSTRACT FROM AUTHOR]

The Santos Basin, offshore Brazil contains a complex set of salt‐tectonic structures, the origins of which are debated, that is, the Albian Gap and the São Paulo Plateau (SPP). The Albian Gap is a ca. 450 km long, 60 km wide feature characterized by a post‐Albian, counter‐regional rollover overlying depleted Aptian salt, and in which the Albian is largely absent. The SPP, located immediately downdip, is defined by a pre‐salt structural high overlain by ca. 2.5 km thick salt. Another prominent feature is the Merluza Graben, a rift‐related depocentre that underlies the southern portion of the Albian Gap and displays significant (3–4 km) base‐salt relief along its main faults. Two competing hypotheses have been proposed to explain the kinematics of these provinces. One invokes post‐Albian extension in the Albian Gap and kinematically‐linked contraction in the SPP. The other invokes post‐Albian salt expulsion in the Albian Gap and salt inflation in the SPP. Recent studies, however, suggest these processes likely alternate in time and space, contributing nearly equally to the evolution of these domains. We apply 3D physical modelling to (i) test this hypothesis; and (ii) to more generally understand how gravity gliding and spreading over three‐dimensionally variable base‐salt relief control regional salt tectonics. The results show a similar salt‐related evolution and structural styles to those proposed in the most recent studies. They also (i) explain the origin of the ca. 25 km wide diapir precursor of the Albian Gap by early salt inflation against base‐salt steps; (ii) show that normal faults with different polarities and rollover types form due to the interplay between gliding and spreading over different base‐salt domains and (iii) provide a mechanism for the origin of strata encased within salt structures. This improves our understanding of the distribution and origin of salt‐related structural styles in worldwide salt basins. [ABSTRACT FROM AUTHOR]

Diagenetic models help explain reservoir quality of siliciclastic strata, which are globally important exploration targets for groundwater, petroleum and carbon sequestration. Siliciclastics occur in salt provinces worldwide but remain poorly studied despite documented deviation from basic eodiagenetic models. A new variation is explained based on evidence from Cumberland Basin strata (Grande Anse Formation, Pennsylvanian, Canada). These strata were deposited in a fluvial setting under semi‐humid to humid climates and represent an unconformable cover sequence over a salt wall. Optical microscopy and scanning electron microscopy, both employing cathodoluminescence, reveal that widespread early diagenetic phases are mostly deleterious to reservoir quality. These pre‐compactional eodiagenetic phases are: (i) variable dissolution/alteration of feldspars, micas and carbonate/evaporite clasts; clay and grain staining iron oxides; and pore‐filling kaolinite; (ii) microcrystalline calcite; quartz overgrowths, prismatic quartz, quartzine chalcedony and blocky quartz, the latter two pseudomorphous after gypsum; and barite; (iii) framboidal pyrite and locally extensive Mg, Fe and Mn‐bearing blocky calcite. The first phase is attributed to a seasonally wetted vadose zone under relatively low pH and positive Eh conditions characteristic of humid climates. In contrast, the second phase is usually associated with evaporitic conditions and arid climates, where authigenesis occurs in the capillary fringe to just below the water table, and where porewaters are much more saline. The third phase is related to authigenesis from shallow burial, anoxic, phreatic porewaters. How is the aforementioned humid/arid dichotomy deciphered? Important may be the distinction between vadose and circum‐water‐table phases. Beneath vadose deposits of the humid climate, the proximity of evaporite rock in the salt wall allows for its localized dissolution, providing abundant Ca, CO3 and SO4 ions to produce anomalously saline, shallow groundwater. Barite and transient gypsum precipitated, the latter subsequently replaced by chalcedony and pseudomorphous silica during sporadic events where flushing of meteoric water temporarily lowered pH. [ABSTRACT FROM AUTHOR]

Continental rifted margins are often associated with widespread, thick evaporite (i.e., salt) deposits and pronounced salt tectonics. The majority of salt basins formed during the latest stages of rifting, prior to continental breakup. We use 2D thermo‐mechanical finite element modeling of lithospheric extension to investigate the interplay between rifted margin architecture, late syn‐rift salt deposition, and post‐rift salt tectonics. We focus on four different types of continental margins: (a) narrow, (b) intermediate, (c) wide, and (d) ultra‐wide margins. We evaluate the: (a) interplay between laterally variable syn‐rift extension, salt deposition and salt tectonics, (b) influence of syn‐rift basin architecture on post‐rift salt flow, (c) spatial and temporal distribution of salt‐related structural domains, and (d) contrasting styles of salt tectonics for different margin types. Narrow and intermediate margins form partially isolated salt basins associated with prominent base‐salt relief, limited translation but significant diapirism, and minibasin development. Wide and ultra‐wide margins form wide salt basins with subtle base‐salt relief that results in significant seaward salt expulsion and overburden translation. These wide margins demonstrate significant updip extension with the development of post‐rift normal faults and rollovers, mid‐margin translation associated with complex diapirism and downdip diapir shortening. All margins contain a distal salt nappe that varies in width and complexity. We also test the effect of different salt viscosities, relative post‐salt progradation rates, and pre‐salt sediment thicknesses. The results are comparable to several examples of salt‐bearing rifted margins and improve our understanding of their dynamics and on the controls on their salt tectonics variability. Plain Language Summary: Rifting of the continental lithosphere can lead to continental breakup and formation of continental margins, which are often associated with widespread, thick salt basins that deform in a ductile fashion and produce complex geological structures. Most of these basins formed during the latest stages of rifting, prior to continental breakup. We use 2D thermo‐mechanical numerical modeling of lithospheric extension to investigate the interplay between rifted margin architecture, late‐syn‐rift salt and post‐rift salt tectonics for four different types of margins: (a) narrow, (b) intermediate, (c) wide, and (d) ultra‐wide. We evaluate the interplay between syn‐rift extension, salt deposition and deformation, the influence of rift basin architecture on post‐rift salt flow, and the contrasting styles and magnitudes of salt deformation for different margin types. Narrow and intermediate margins form isolated salt sub‐basins associated with prominent relief, limited seaward translation but significant vertical salt flow. Wide and ultra‐wide margins form broad salt basins with subtle relief, significant seaward salt expulsion, updip extension, translation and downdip shortening. All margins contain a distal salt sheet advancing laterally over newly formed oceanic crust. The results can be directly compared to several examples of salt‐bearing rifted margins worldwide and provide an improved understanding of their dynamics. Key Points: We use geodynamic models of lithospheric extension to investigate post‐rift salt tectonics for different types of rifted marginsNarrow margins form partially isolated salt sub‐basins associated with prominent relief, limited seaward translation but major diapirismWide margins form large salt basins with low relief, major seaward salt expulsion, nappe advance, updip extension and downdip shortening [ABSTRACT FROM AUTHOR]

Analog modeling is used to study the role played by the inherited salt‐sediment architecture of a salt‐bearing rifted margin, developed by minibasin downbuilding and margin‐scale gliding, and then incorporated into a fold‐and‐thrust belt system influenced by surface processes. Inherited salt bodies localize contractional deformation at different scales and the salt‐sediment architecture determines structural styles of fold‐and‐thrust belts. In our analog models, a large‐transport thrust detached along allochthonous model salt (silicone polymer) accumulated in a former distal raft system. And the squeezing of salt walls, together with the tilting of minibasins, accounted for most of the shortening in a salt wall‐minibasin province. Shortening and surface processes promote the extrusion and erosion of about 75% of the original model salt. The role played by salt tectonics during the contraction of salt‐bearing rifted margins could be underestimated because of the low salt‐sediment ratio found in fold‐and‐thrust belts. Our modeling results are compared with and assist in the interpretation of a section along the Northern Calcareous Alps. Key Points: Salt distribution determines the evolution and architecture of a salt‐bearing rifted margin incorporated into a fold‐and‐thrust belt systemSalt extrusion and erosion lead to an underestimation of the original amount of salt which may compromise structural restorationsAnalog modeling results support the salt‐influenced evolutionary model for the Northern Calcareous Alps [ABSTRACT FROM AUTHOR]