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Using integrated Interferometric Synthetic Aperture Radar (InSAR) datasets (Envisat: 2003–2009; Sentinel-1: 2014–2018), local gravity surveys, and passive seismic data, we investigated the environmental hazards associated with the rise of the Miocene Jazan salt diapir (JZD; ~ 2 km2) within Jazan city, Saudi Arabia, and identified areas at risk in its immediate surroundings. Our findings include (1) the JZD outcrop and its northern, southern and western bordering areas have been undergoing substantial uplift (up to 4.7 mm/yr), whereas the sabkhas to the east are witnessing subsidence (up to − 7.5 mm/yr); (2) a low Bouguer anomaly (7.5 mGal) was observed over the JZD relative to its surroundings (8.5–12 mGal) with the steepest gradient along its eastern side; (3) strong and clear horizontal/vertical (H/V) spectral ratio peak and high frequency (5–10 Hz) over the JZD outcrop and areas proximal to its western margin, but areas to the east have a weak H/V peak and low frequency (1.5-3 Hz); (4) drilling confirmed presence of a shallow (4 m) salt bedrock layer west of the JZD and the absence of this layer to its east (up to depths of 60 m); (5) uplift patterns along the diapir margins are indicative of near-vertical contact along the JZD eastern margin and less steep contacts along the remaining margins; and (6) additional near-surface diapirs could potentially be identified in the vicinity of the JZD using our integrated approach.

Identifikasi keberadaan diapir merupakan hal esensial dalam pertambangan batubara mengingat sifatnya yang seperti intrusi dapat mengurangi cadangan batubara. Seperti yang teramati pada area pertambangan PT Arutmin Indonesia. Kehadiran mud diapir pada PIT HG telah terbukti mengurangi cadangan batubara, dengan luas area terdampak 0,7 Ha. Selain itu, beberapa diapir diperkirakan belum terpetakan karena terletak di bawah permukaan dan belum tersentuh oleh pengeboran eksplorasi PT Arutmin Indonesia, sehingga tanda-tanda permukaan seperti singkapan batuan dan struktur geologi maupun provenance diapir dapat menjadi petunjuk yang penting. Oleh sebab itu, tujuan penelitian ini adalah untuk mengetahui pola distribusi dan korelasi antara keberadaan diapir dengan struktur geologi, stratigrafi, dan provenance teridentifikasi yang kemudian dapat digunakan untuk memperkirakan persebaran diapir lainnya. Analisis dilakukan pada data primer hasil pemetaan geologi lapangan sebagai representasi struktur geologi maupun stratigrafi makro sebagai identifikator provenance. Hasil pemetaan lapangan seluas 60 km 2 menunjukkan daerah penelitian terdiri dari tiga satuan batuan, yaitu satuan batupasir-batulempung termasuk lima singkapan diapir di dalamnya, satuan batulempung, dan satuan intrusi andesit. Satuan batupasir-batulempung memiliki kesetaraan dengan Formasi Tanjung yang merupakan formasi batuan sedimen tertua di daerah penelitian. Struktur geologi yang berkembang pada daerah penelitian adalah sesar geser menganan serta sesar geser mengiri yang berperan besar sebagai pengontrol keterdapatan diapir. Analisis stratigrafi menunjukkan provenance mud diapir berasal dari satuan batupasir-batulempung, Formasi Tanjung. Berdasarkan hasil analisis di atas, persebaran mud diapir berkorelasi dengan persebaran struktur geologi terutama sesar geser dan persebaran satuan batupasir-batulempung. Karena hal tersebut, maka pada area Tambang Senakin terdapat potensi keberadaan mud diapir yang tidak tersingkap di permukaan dan dapat menyebabkan hilangnya cadangan batubara termodelkan yang jauh lebih besar dari yang telah terbukti saat ini. Sebagai langkah preventif untuk mengetahui keberadaan diapir yang belum teridentifikasi, maka penulis membuat peta potensi keterdapatan diapir pada area penelitian di PT. Arutmin Indonesia Tambang Senakin. Untuk mendapatkan hasil yang lebih baik, penulis menyarankan pihak pelaksana tambang untuk melakukan analisis geolistrik pada titik yang telah direkomendasikan penulis. Kata kunci: mud diapir, Formasi Tanjung, analisis stratigrafi, pemetaan geologi lapangan, cadangan batubara ABSTRACT Identifying diapir occurrence is essential in coal mining activities knowing it behaves like an intrusion that can lead to a reduction in coal reserve. As we can observe in PT Arutmin Indonesia mining field. The presence of mud diapir on PIT HG has been proved to cut down its coal reserve, with the total area affected is 0,7 Ha. Since not all of the mud diapirs are exposed to the surface, we suspected that some of them are still yet to be found by PT Arutmin Indonesia’s exploration. Hence, diapir provenance and surface hints such as outcrop and geological structure can be a crucial indication. Therefore, this study objectives are to identify distribution and correlation between diapir occurrence and geological structures, stratigraphy, and its identified provenance that can be used to estimate other diapirs. This study began with geological mapping to identify the geological structure and its stratigraphy. Stratigraphic analysis is carried out as provenance identifier. Geological mapping in 60 km 2 area concluded that the area have three lithological units, sandstone-claystone unit including five diapir outcrops, claystone unit, and andesite intrusion unit. Sandstone-claystone unit is equivalent to Tanjung Formation which is the oldest sedimentary rocks formation in the area. Dextral strike slip and sinistral strike slip faults which are found in the area considered to have a significant effect on diapirs occurrence. Further stratigraphic analysis shows that the the mud diapir’s provenance is from Tanjung Formation. Based on these analyses, we conclude that mud diapir occurrence has a good correlation to geological structures especially the strike slip faults and sandstone-claystone unit distribution. Consequently, Senakin Mine Field has a chance of losing its potential coal reserve much bigger than previously estimated due to unidentified mud diapirs occurrence below the surface. We will provide a mud diapir occurence potential map as a preventive measure in identifying unknown diapirs. We also suggest doing subsurface resistivity analysis for further detailed and better results. Keywords: mud diapir, Tanjung formation, stratigraphic analysis, geological mapping, coal reserve

A geophysical study carried out in the framework of the water resources recognition within the Essaouira coastal area (Morocco) enabled to outline the spatial distribution of the Plio-Pleistocene and Cretaceous formations. It helped to determine the thickness and extension of the main aquifer used for irrigation purpose. The overall aim of this study is to highlight the hydrogeological structures of Essaouira Basin. A total of 45 vertical electrical soundings (VES) were measured using linear Schlumberger array configuration with a maximum half-length (AB/2) of 1000 m along eight sections of 126 km total length. The number of soundings constituting the eight VES profiles depends on the topography and the obstacles encountered. The VES data were processed and interpreted. According to the thematic maps of the study area, the results indicate the existence of three types of VES with apparent resistivity values ranging from 44 to 320 Ω m. In relationship with wells and mechanical drillings existing in the area, the analysis of the results obtained made it possible to derive from the quantitative and qualitative maps the different apparent resistivity variations of the aquifer and aquiclude geological layers. The careful examination of these maps shows that the region around the Qsob River is of interest from a hydrogeological point of view. It is represented by a significant thick layer given the large extension of the resistive Plio-Pleistocene and Cretaceous formations. Geophysical studies show that this region is partially protected from marine intrusion given its location between Tidzi Diapir and hidden diapir from Essaouira which little plays the role of barrier. It is crossed by the Qsob River which lends itself as the main source of both these layers. The electrical discontinuities emerging from the superposition of the different maps, E-W, NE-SW and NNE-SSW oriented, are abundant and dense in the north Haha region (Qsob River). Generally, the salt water circulates along these discontinuities from West to North and Northeast which explains the abundance of low apparent resistivity values recorded northeastwards. This geophysical reconnaissance is the most important for water supply of this area affected by increasingly long periods of drought.

Salt diapirism is often associated with potential hydrocarbon energy resources, and detecting active diapirs can strongly affect the prospect to discover new gas and oilfields. Here we use InSAR techniques as a proxy to evaluate surface deformation in the Diapiric Fold Zone located in the East Carpathians Bend. Significant surface uplift (~ 5 mm/year) is identified in a relatively small region not previously known for the presence of an actively rising salt diapir. Using high-resolution two-dimensional thermomechanical numerical simulations of salt diapirs intrusions, we show that that the observed surface deformation can be induced by a relatively small salt diapir (1–2 km in diameter) rising from an initial salt layer located at 17 Pa s. The best fitting model reveals the presence of a relatively small salt diapir that has not pierced yet the entire sedimentary layer and is located just 1–2 km below the surface.

The Salar de Atacama basin is the main topographic low of the Preandean Depression of the Central Andes of northern Chile. Although numerous studies have been carried out in this area, the origin of the depression is still a matter of debate. The integration of seismic reflection and surface structural data along the basin allows the characterization of Oligocene and Neogene tectonic activity of the Salar de Atacama. A key element to unravel the Neogene to recent history of the basin is found along the Cordillera de la Sal, which comprises more than 3000 m of continental sedimentary succession assigned to the San Pedro Formation. Detailed analysis of the seismic data shows that large depocenters involving distal alluvial facies and evaporitic members of the San Pedro Formation accumulated in close relation with Oligocene extension. Extension was controlled by a first order normal fault located along the western flank of the Atacama basin, which appears as a key structural feature of the internal architecture of the Salar de Atacama. The rise of the Cordillera de la Sal ridge during the Neogene involved compression and sinistral strike slip in its southern domain, in combination with salt diapirism in its north domain. This transition is related to the thickness and distribution of the evaporitic lower members of the San Pedro Formation, which also controls the depth of the detachment level beneath the Cordillera de la Sal. Our results show that the current relief of the Salar de Atacama basin is mainly due to Oligocene extension and subsequent Neogene tectonic inversion.

The Gaoping River-Gaoping Submarine Canyon (GPC) is one of the dispersal river systems in the world. Tens of tons of terrestrial sediments discharge per year at the mouth of the river, where gravity-driven flow can damage the telecommunication cable along the 260-km-long GPC; to the east of the GPC, the continental shelf has been eroded. To understand this geological phenomenon, high-resolution sparker seismic data around the continental shelf as well as parallel and across the GPC were collected. Deep-towed sub-bottom profiler (SBP) data and data from shipboard acoustic Doppler current profiler were also collected. Three major system tracts off southwest Taiwan were identified, based on which the coastline of the last glacial maximum was identified at approximately 138 m below the current sea level. Analysis of the deep-towed SBP profiles suggested sandy sediment overflows through breakages on the east bank of the GPC. A convergence of bottom currents with a speed of up to 1.5 m/s flowing southeastward has eroded the continental shelf intensively, forming the Xiaoliuchiu channel. Although a mud diapir is active to the east of the GPC and forms the Xiaoliuchiu islet, it has been eroded at the Xiaoliuchiu channel. The average erosion rate on the east bank of the GPC was estimated to be approximately 609 cm/ka in the past 8.2 ka; between the GPC and the Xiaoliuchiu islet, the continental shelf is wasted due to severe seabed slumping.

The termination of a deep-sea turbiditic channel represents the ultimate sink of terrigenous sediment in the oceans or lakes. Such environment is characterized by rapid slope decrease and by loss of confinement of turbidity currents. It results in the deposition of Channel-Mouth-Lobes that can be separated from the channel mouth by an erosional (scoured) or by-pass dominated Channel-Lobe Transition Zone. Several factors can control the occurrence, extent and morphologic expression of the area such as the slope break angle, the upslope and downslope angle and the mud/sand ratio in flows. Disentangling these factors remains challenging due to the scarcity of outcrops and to the usual faint morphologies and low thickness of deposits. With bathymetric and seismic data we calculated the morphometric parameters of 8 channel-levees and their Channel-Mouth Lobes from the deepest area of the Rhone fan, a mud-sand rich system, and among which the youngest one (called neofan) was deposited at the end of the Last Glacial Maximum between 21.5 and 18.3 ka cal. BP. Emplacement and shape (finger-shaped or pear-shaped bulges) of Channel-Mouth Lobes is controlled by the seabed morphology (adjacent channel-levees and salt diapirs). A less prominent morphology of the neofan is attributed to premature quiescence related to the post sea-level rise sediment starvation. We show that the occurrence and expression of a Channel-Lobe Transition Zone is controlled by the gradient upstream of the channel mouth slope break. The extended Channel-Lobe Transition Zone and detached lobe of the neofan are attributed to the high upslope gradient (0.26°) while the less detached or attached lobes of other channel-levees is attributed to lower upslope gradient (0.13°). We show that scouring and scours concatenation into flutes at the Channel-Lobe Transition Zone is a major driver for the inception of channels and further confinement of turbidity current. For the first time we show that concatenation of scours in shingled disposition developed an incipient channel sinuosity at this very early stage of channel development. The channel-levee can extend downslope nearly instantaneously by tens of kilometers when isolated nascent channels connect to the channel mouth.

The Leviathan gas field is the largest accumulation so far discovered in the Southern Levant Basin within the turbiditic Tamar Sand Complex. The discovery of this and other fields in the basin was made possible following acquisition of a vast amount of data since 2000. A consensus has been reached that the basin is dominated by Early Mesozoic extensional blocks related to opening of the Neotethys while Miocene folds formed as a result of its closing. Through the study of geophysical data over the Leviathan gas field and its vicinity, it is suggested that most of what we observe today has been formed since the Early Miocene and that the alleged old blocks are actually intrusive bodies. Their structural timing is accurately constrained by well and seismic data but not their composition, as none has yet been penetrated at any borehole. Mud diapirism is currently assumed, as volcanic or magmatic origin is discarded by magnetic data and salt is yet a remote possibility. The tectonic reconstruction suggests that the Levant Basin developed during the Mesozoic and Early Cenozoic as a set of regional highs and lows that were buried since the Early Tertiary until the Early Miocene by thick conforming sequences including potential reservoir rocks such as the gas-bearing turbiditic sands. It was then subject to an extensional tectonic regime associated with diapirs in the southern part of the basin that formed folded structures while rotational blocks developed to the north, offshore Lebanon. The implications of this tectonic setting on petroleum systems are of prime importance; widespread intrusions may have breached old traps, if they existed. On the other hand they formed potential traps such as the proven gas-filled structures and potentially others at depth. Presence of reservoir rocks and the timing of expulsion and migration from deep sources are the main geological risks.

Dolomites are well-known minerals; belonging to the Infra-Cambrian Hormuz Series lies within the salt domes of southern Iran. In this paper, the origin and alteration of dolomitic rocks of Paskhand and Deh-kuyeh salt diapirs in the area of Larestan (southern Iran) are investigated. Based on petrographic (size and fabric) studies, we recognize four dolomite types that consist of very fine-to-fine crystalline dolomite (D1), neomorphic dolomite (D2), fine-to-medium crystalline euhedral-to-subhedral dolomite (D3), and pore- and fracture-filling dolomite (D4). The dolomite samples with up to 26% iron can be called ferruginous dolomites. Some igneous rock patches to gehter with hydrothermal iron veins are observable in the salt domes of Larestan. Oxygen and carbon isotope values of black and white, and altered red dolomite of Paskhand and Deh-kuyeh salt domes, are equal to − 12.35 to − 18.78 for δ18OPDB and − 5.48 to − 8.49 for δ13CPDB; values enriched δ180 with low-temperature (~ 70 °C) conditions are related to D1 dolomites and values depleted δ180 with higher temperatures (~ 270 °C) are related to D3 and D4 dolomites. The most important source for secondary dolomites is deeper hydrothermal and catchment sources, which ascended through faults during the intrusion. Meteoric waters can be mentioned as less important sources for these types of dolomites. We reported sassolite B(OH)3 mineral in Deh-kuyeh salt diapir for the first time in this paper. This mineral is only observed in the areas which have famous riftings Fumarol. Therefore, in this paper, the existence of sassolite in the studied area could be considered one of the most important the origin of the composing elements of Hormuz rocks from fumarols which are formed in an extensional regime.

The architecture and distribution of mud diapirs are shaped by tectonic activity, sediment filling and unbalanced loading characteristics. Mud diapir development also controls spatial variations of intraslope basins in slope areas and can spur upward fluid migration with diapiric intrusion. The offshore area of southwestern Taiwan is an incipient collision zone in which thick sequences of deep marine sediments filled a rapidly subsided foredeep basin during the Pliocene. Large volumes of deposited sediment serve as source materials of diapiric ridges that extend NNE-SSW, and some mud diapirs even extend to on land SW Taiwan with subsurface signatures of gas. This study examines relationships between mud diapir and intraslope basin development in convergent tectonics through seismic and bathymetry data analyses. Four types of mud diapirs are identified: (1) buried symmetrical diapirs; (2) symmetrical diapirs extruded above the seafloor; (3) asymmetric and irregular diapirs; and (4) small individual diapirs manifested as mud intrusions found in local areas. A 3-stage model is proposed as a tool for describing the development and distribution of these types of diapirs. We further examine the relationship between mud diapirs and intraslope basin development patterns by analyzing 2D and 3D seismic images to reveal structural and sedimentary processes occurring in the Lower Fangliao Basin. This basin is characterized by BSR and amplitude anomalies of seismic profiles and is a prospect of the Taiwanese gas hydrate investigation project. An 8-stage development model with six depositional units is proposed as a means to explain the evolution of diapirs, submarine canyons, and fold and fault activities in the Lower Fangliao Basin, in turn revealing the relationship between mud diapir formation and intraslope basin development offshore of southwestern Taiwan.

In recent years, salt diapirs have been widely used for gas storing, hazardous waste disposal, mining, and petroleum production. The rate and pattern of active movement in salt structures are crucial to be obtained before planning these industrial utilizations. The central basin of the Iranian plateau represents well-exposed and -preserved diapirs that can be considered as an analog for other salt basins around the world where the exposures are not as good. Integration of the Interferometric Synthetic Aperture Radar (InSAR) technique with remote-sensing structural mapping permits us to study the active surficial deformation of eight salt diapirs in the Kalut basin in central Iran. We classify the Kalut diapiric structures into salt walls, massifs, stocks, and welds. We then use 75 Single Look Complex (SLC) IW scenes acquired on the ascending collected from November 2014 to November 2018 and 62 SLC images on descending geometries collected from October 2014 to January 2018, both covering the same period. The Sentinel-1 images are processed by the Small BAseline Subset (SBAS) approaches to define vertical and horizontal displacement maps revealing that the Kalut basin is one of the most-active present-day diapiric systems in the world, its eight salt diapirs are rising, and none of them subsides. Maximum calculated rates of growth reach 8 mm/yr in vertical and ~ 2 mm/yr in horizontal directions, suggesting that in general vertical displacements play a significant role in the deformation of this salt-controlled basin. Salt stocks are uniformly rising in their crestal domain (up to 8 mm/yr) with lateral spreading along their flanks (1–2 mm/yr). The larger salt walls are more active and rising faster (8 mm/yr) than smaller ones (3 mm/yr), while welded areas are inactive. These rising salt diapirs are flanked by seasonal depocenters accumulating up to 10 mm/yr of fluvial, evaporitic, and aeolian deposits.

A georeferenced database is used to analyse the distribution of Quaternary soft-sediment deformation structures across France. They include features visible in aerial photographs (soil stripes and cells) and features described in cross-section (involutions). Overall, there is no clear relation between the distribution of features and the locations of known faults and earthquakes in available databases. In contrast, the distribution agrees with that of Pleistocene periglacial structures. Most of the soil stripes and cells are located north of 47.5°N, i.e. in the zone of ice-wedge pseudomorphs, and can be interpreted as deformation structures of an active layer in permafrost terrain. The height of the involutions is influenced by the nature of the filling, the substrate and latitude. Deformation structures are larger in coarse material, reflecting the role of drainage and thermal conductivity. Their height increases northward to ca. 2 m at 48°N. This is thought to reflect the increase in thickness of the layer subjected to freeze–thaw cycles. Bowl-shaped structures separated by coarse pillars, which correspond to soil stripes seen in section, have formed on slopes in settings unfavourable to the generation of high pore-water pressure. Their genesis is probably related to differential frost heave. Ball-and-pillow structures and diapirs are common in flat and poorly drained terrain, and formed by liquefaction and sometimes fluidisation in a periglacial setting. Copyright © 2017 John Wiley & Sons, Ltd.

The Trans Indus-Salt Range, located in northern Pakistan, is one of the most tectonically active fold-and-thrust belts and comprises three main regions: the Potwar-Salt Range, the Kohat-Surghar Range and the Bannu Basin-Khisor Range. Of these, the Bannu Basin is the least studied and only a handful of publically accessible datasets and publications are available. Recently made public 2D seismic profiles and well data from the Bannu Basin indicate the presence of salt as well as evidence for a main detachment surface which is Neoproterozoic in age. Our findings suggest that the Salt Range Formation could be the main detachment for the entire basin. Interpretation also shows a Miocene-Eocene basin-wide unconformity that marks the Himalayan orogenic event which separates the pre-Himalayan from the syn-Himalayan sedimentary units. On the basis of seismic reflection data, we conclude that the basin experienced three main tectonic settings. An early stage of pre-Himalayan passive tectonic environment is followed by the compressional Himalayan tectonics which resulted in uplifted areas sourcing the fluviatile fill of the subsided basin. During this time, sedimentation from the northern margin of the basin may have influenced the southward flow of salt. This is followed by a more recent stage of thrusting that produced folds and thrusts deforming all of the sedimentary units. Structural geometries suggest that prospective traps are developed mainly in the anticlines outlining the eastern and western boundaries of the Bannu Basin, as well as the southern zone of the basin. Furthermore, the presence of salt diapirism and transpression zones together with numerous oil seeps in and around the basin increase the probability of hydrocarbon accumulation and indicate great potential for future exploration.

The Gruene and Verde mud diapirs, which range in size from 70 to 95 m in diameter, are exposed within the Wilkins Peak Member of the Eocene Green River Formation near Flaming Gorge Reservoir, southwest Wyoming. These diapirs are sourced from the lower unit of the Wilkins Peak Member (lower, middle, and upper units can be defined based on dominant lithology), and were emplaced into the upper unit of the Wilkins Peak Member, cross-cutting hundreds of meters of strata. The structures contain brecciated dolomicritic and lime mudstones with minor amounts of siliciclastic clays. Pervasive quartz veining is present throughout both diapirs. Though heavily disturbed, original bedding can be seen in both localities, either dipping radially outward towards the margins of the diapir as is dominant at the Gruene diapir or tilted but near horizontal as is the dominant expression at the smaller Verde diapir. The Gruene diapir can be seen in contact with several fluvial sandstone bodies within the upper Wilkins Peak strata in outcrop, and these fluvial sandstones transition from regional, near-horizontal dips to steeply dipping beds and bedsets within 50 m of the diapir. These sands show no signs of brittle deformation, and dip ranges from 20 to 50° radially away from the center of the diapir to the north, west, and east where sands are observed. These are interpreted here to have been deformed pre-lithification, at or near the surface, by the rising mud diapir, offering an important control on the timing of diapirism near the end of the early Eocene. Deformation structures such as clastic dikes, brecciation, and convoluted bedding have been documented by others at or near this stratigraphic interval in Utah, Wyoming, and Colorado, and these smaller structures have been interpreted as seismites. We suggest that these mud diapirs are a larger-scale expression of this same seismic activity.

Involutions and small frost fissures have been recorded over a wide area of the lower terrace of the Warta River valley (central Poland). They developed at the lithological boundary between an organic‐rich deposit with a thin peat layer (unit b) and an underlying fluvial sandy deposit (unit a). Most of the involutions are products of a reversed density gradient and loading, or developed under the influence of cryohydrostatic pressure. Among them are drop‐like and flat‐bottomed structures, diapirs, flame‐like and fold structures and irregular involutions. Some frost fissures have also been recorded in the same stratigraphic position. The sedimentological properties and formative mechanism of the involutions, together with environmental data (lithology, groundwater conditions, snow cover and vegetation), reveal their origin as periglacial. Radiocarbon dating indicates that the structures formed during the Younger Dryas. Overall, the involutions and frost fissures indicate that permafrost re‐aggraded in this region of central Poland during the Younger Dryas. Copyright © 2017 John Wiley & Sons, Ltd.

A reservoir in the upper Miocene Huangliu formation from the Dongfang (DF) area of Yinggehai Basin is characterized by overpressure and hydrothermal fluids with CO2 accumulations. The shallow-marine gravity-flow deposits of the Huangliu formation provide an opportunity to study the impact factors on reservoir quality under overpressure and a CO2-rich environment. The current study examined the impact of sandbody types, diagenetic alteration, high-overpressure and CO2 accumulations on reservoir quality by comparing between the DF-A (CO2-rich) and DF-B (CO2-poor) areas. The channel sandbody, sheet sandbody and neritic sandbar are recognized from the Huangliu formation in the study area. The sandbody type is the most important factor for controlling reservoir quality. The bottom current reworked channel (BCRC) and reworked sheet sandstones of gas layer #I in the DF-B area have the best reservoir properties. This is due to winnowing away the original (very) fine component (such as mud) by bottom current, resulting in a slight increase of grain size and marked increase of pore-throat radius and permeability. Mechanical compaction and cementation are the main diagenetic factors for reducing primary porosity. High-overpressure can protect the primary porosity to some extent by resisting the compaction effect. The intrusion of late CO2-rich hydrothermal fluids affects mesodiagenesis in two ways. On the one hand, it can cause intense dissolution of detrital minerals and early calcite cements, resulting in a higher proportion of secondary porosity in the CO2-rich DF-A area than in the CO2-poor DF-B area. On the other hand, it can result in precipitation of cements, such as siderite and ankerite, through CO2-water-rock reactions. Overall, CO2 accumulations has an insignificant contribution on the increase of porosity. Intense dissolution by CO2 accumulations can increase the connectivity of pores and permeability, whereas precipitation of minerals leads to decreased permeability.

Geological-geophysical methods were applied to provide deeper insight into the nature of unique relict lagoonal sediments exposed on the underwater slope of the Curonian Spit. The study of textural features and morphology of the deformed lagoonal sediments indicates a similarity of their formation mechanism with clay diapirism. Analysis of seismoacoustic data and side scan sonar survey allowed us to establish the configuration of paleolagoon and to determine the direction of dune migration in the past.

Southern Iran hosts abundant salt karst phenomena in numerous salt diapirs. This paper provides a new insight into the relationships among climate, cap soil and salt karst hydrogeology. Cave systems were documented and mapped. Soil, drip, stream, and flood waters from different environments were studied at several diapirs. It was revealed that the soil water chemistry depends on both the climate and cap soil thickness. In semi-arid climates, a thick cap soil forms (>3 m) and water has very low TDS values (0.15 g/l). In arid climates, a shallow cap soil forms, and soil water is gypsum-saturated with low dissolved halite contents. In both environments, drip waters from salt caves and springs displayed high TDS values (255 to 347 g/l). This is explained by the dissolution of halite and minor anhydrite/gypsum, a K-Mg sulfate and sylvite. Spring water plots on a local meteoric water line, whereas drips in caves have an evaporative signature. The flash flood runoff is dominated by event rain water based on isotopic data, while springs are dominantly supplied by a base flow component. The mean residence time of water on the diapirs is controlled by the cap soil thickness. Water residence times may reach several hundreds of years on a thick cap soil based on an exponential model butsoil.

The first marine gas hydrate expedition in China has been conducted by Guangzhou Marine Geological Survey in the Shenhu Area, northern continental slope of the South China Sea. Previous study has analyzed the P-T conditions, geophysical anomalies and saturation calculations of these gas hydrates, but has not documented in detail the migration of gas-bearing fluids in the study area. Based on the interpretations of 2D/3D seismic data, this work identified two types of migration pathways for gas-bearing fluids in the Shenhu area, i.e., vertical and lateral pathways. The vertical pathways (large-scale faults, gas chimneys and mud diapirs) presented as steep seismic reflection anomalies, which could be traced downward to the Eocene source rocks and may penetrate into the Late Miocene strata. The deeper gases/fluids might be allowed migrating into the shallower strata through these vertical conduits. However, the distributions showed distinct differences between these pathways. Large-scale faults developed only in the north and northeast of the Shenhu area, while in the drilling area gas chimneys were the sole vertical migration pathways. Since the Pliocene, normal faults, detachment faults and favorable sediments have constituted the lateral pathways in the Shenhu gas hydrate drilling area. Although these lateral pathways were connected with gas chimneys, they exerted different effects on hydrate formation and accumulation. Gas-bearing fluids migrated upward along gas chimneys might further migrate laterally because of the normal faults, thereby enlarging the range of the chimneys. Linking gas chimneys with the seafloor, the detachment faults might act as conduits for escaping gases/fluids. Re-deposited sediments developed at the early stage of the Quaternary were located within the gas hydrate stability zone, so hydrates would be enriched in these favorable sediments. Compared with the migration pathways (large-scale faults and mud diapirs) in the LW3-1 deep-sea oil/gas field, the migration efficiency of the vertical pathways (composed of gas chimneys) in the gas hydrate drilling area might be relatively low. Description and qualitative discrimination of migration pathways in the Shenhu gas hydrate drilling area are helpful to further understand the relationship between good-quality deep source rocks and shallow, mainly biogenically-produced, hydrates. As the main source rocks of the Baiyun sag, lacustrine mudstones in the Wenchang and Enping Formations may provide thermogenic methane. Gas chimneys with relatively low migration efficiency created the vertical pathways. Caused by the Dongsha tectonic movement, the release of overpressured fluids might reduce the vertical migration rates of the thermogenic methane. The thick bathyal/abyssal fine-grained sediments since the Late Miocene provided migration media with low permeability. These preconditions may cause carbon isotopic fractionation of thermogenic methane during long-distance vertical migrations. Therefore, although geochemical analyses indicate that the methane forming gas hydrate in the Shenhu area was mainly produced biogenically, or was mixed methane primarily of microbial origin, thermogenic methane still contribute significantly.

Analysis of current temperature data in the Canadian Arctic Archipelago results in the recognition of two major thermal regimes. High temperature regions are observed where salt diapirs and salt cored anticlines are present. Low temperature fields are observed along the western and southern basin margins and around Cornwall-Amund Ringnes islands, where regional Mesozoic aquifers are exposed to surface, connected to basin boundary faults, or regional unconformities. Meteoric and Holocene sub-glacial water recharge are inferred to be responsible for the low geothermal regime and low formation water salinity. Neither exhumation associated with the Eocene “Eurekan” orogeny nor volcanic intrusion associated with opening of Amerasia Basin in late Jurassic-early Cretaceous have been interpreted to be a significant influence on the present day temperature field, although thermal indicators show evidence of elevated thermal alteration of organic matter pointing to earlier, but now dissipated, thermal anomalies.

Mangerak salt diapir is in the South West of Firuz Abad in Fars province, southern Iran and structurally, it is exposed in the simple folded belt of Kohzad Zagros. This diapir, now, is located in a transtentional zone in the overlapping parts of Koreh Bas right fault zone. The origin of this diapir is evaporative series of Hormuz, at the beginning of the Cambrian and ending Precambrian age. In this paper, we investigated tectonic structures around the salt dome of Mangerak. By promoting this salt dome, a variety of structures, such as marginal reverse faults, radial normal faults, folds and caves have been developed. In addition, many changes can be seen in the status line, and the amount and direction of the strata dip, thickness of rock units, and facies change, that all showed the downbuilding phenomenon in the diapir. The method was based on structural desert surveys and relevant measurements. The results show that salt domes above were rising during the Late Cretaceous-Paleocene, and pre-deformation of Zagros and in connection with basement Fault of Korebas, and probably, when sedimentation was in the Zagros basin, they have been exposed in the form of an island. Zagros deformation at the same time, the pressure released from the collision zone on the north side of the East and its wave motion, to the South West, exerts more pressure on the salt horizons and helps them to erupt. About Mangerak salt dome, which is exposed on the side of the Sayakh anticline axis and Basement fault of Korebas, two phenomena are effective in its exposing. Analytical modeling shows the life of the outcrop 31,000 years that this age is consistent with the effects of salt dome Neotectonic.

We adopted 106 campaign-mode GPS observations and 310 precise leveling measurements between 2002 and 2010 to understand the present-day crustal deformation in mudstone area and to estimate the earthquake potential of the Hsiaokangshan (HKSF) and the Chishan faults (CHNF) in southwest Taiwan. Horizontal velocities east of the CHNF are ~ 66 mm/yr, 270° and gradually decrease westward to ~ 15 mm/yr, N259°. A horizontal velocity gradient of ~ 15 mm/yr is shown between the HKSF and CHNF. Subsidence rates west of the HKSF and east of the CHNF are ~ 5–10 mm/yr, while the uplift is observed between these two faults in the highest elevation with the maximum rate of ~ 18 mm/yr. The observed deformation patterns are difficult to be fully modeled by 2D kinematic fault model. Field relationships within the vertical shear zones of the mudstone therefore indicate that the deformation pattern may be also controlled by a relic onshore mud diapir that is still experiencing vertical uplift. Consistency between the geological and geodetic vertical velocities, weak rock strength, and no destructive earthquakes over the last 100 years imply that faults (HKSF) within the mudstone area are creeping. However, the CHNF or the associated decollement may still have earthquake potential.

An analytical review of recent papers on the themes “Fluidolites”, “Clay diapirism”, “Clay injection and extrusion” is offered. These phenomena correspond fundamentally to fluid displacement (water, gas, clay and organic matter), whereas massive sedimentary uplift corresponds to large vertical displacement of stratified solid levels but the deeper cause of the latter could partly be the intrusion of mud plugs. The dynamic phenomena controlled by the development of overpressure at depth, contributing to sedimentary mobilization are reported. These processes include clay mineral dewatering, thermogenic degradation of organic matter and deep high-temperature leaching of terrigenous sediments with formation of mud volcanoes.

Recently acquired bathymetric and high-resolution seismic data from the upper slope of Santos Basin, southern Brazilian margin, reveal a major geomorphological feature in the SW Atlantic that is interpreted as a carbonate ridge - the Alpha Crucis Carbonate Ridge (ACCR). The ACCR is the first megastructure of this type described on the SW Atlantic margin. The ~17 × 11-km-wide ring-shaped ACC R features tens of >100-m-high steep-sided carbonate mounds protruding from the surrounding seabed and flanked by elongated depressions. Comet-like marks downstream of the mound structures indicate that the area is presently influenced by the northward flow of the Intermediate Western Boundary Current (IWBC), a branch of the Subtropical Gyre that transports Antarctic Intermediate Water. Abundant carbonate sands and gravels cover the mounds and are overlain by a biologically significant community of living and dead ramified corals and associated invertebrates. The IWBC acts as a hydrodynamic factor that is responsible for both shaping the bottom and transporting coral larvae. We contend that the ACCR was formed by upward fluid flow along active sub-surface faults and fractures that formed by lateral extension generated by the ascending movement of salt diapirs at depth. The ACC R provides an important modern and accessible analogue for a seabed carbonate build-up related to sub-surface hydrocarbon systems., Acknowledgements are also due to the São Paulo Science Foundation (FAPESP grants 2014/08266-2, 2015/17763-2, and 2016/22194-0). MMdeM acknowledges the Brazilian National Research Council (CNPq, grant 300962/2018-5). The partnership between MMdeM and the US was supported by FAPESP (grant 2017/50191-8 – SPRINT Program). The partnership between MMdeM and F.J.L. was supported by CNPq (grant 401041/2014-0). The authors gratefully acknowledge support from Shell Brasil through the BIOIL project at the Oceanographic Institute of the University of São Paulo and the strategic importance of the support given by ANP through R&D levy regulation.

Northwestern Hellas Planitia hosts landforms that are unique on Mars, e.g., the so called honeycomb and banded (aka “taffy pull”) terrains. Recently, robust formation models for the ∼6 km large honeycomb depressions involving salt or ice diapirism have been formulated. However, the nature of the banded terrain, a ∼30,000 km² area characterized by a decameter- to kilometer-scale pattern of curvilinear troughs, has remained elusive. While previous interpretations range from deep-seated, honeycomb-related outcrops to a younger veneer, recent reports of putative periglacial features (e.g., potential thermokarst) strongly indicate it to be a relatively thin, volatile-related surface unit. In order to further constrain the origin and nature of the banded terrain, we investigated the northwestern Hellas basin floor employing various datasets. We mapped the banded terrain's extent at high precision, showing that it partially superposes the honeycomb terrain, but also occurs up to ∼240 km away from it. Via stratigraphic analyses and crater size-frequency measurements, we bracketed the age of the banded terrain between ∼1.9 and ∼3.7 Ga. Furthermore, the banded terrain can be differentiated into two types, ridged and creviced, with the former predominantly occurring among the lowest reaches of the terrain's ∼2 km topographic extent. We also produced a grid map (2 × 2 km box size) of the entire banded terrain and identified no large-scale (> 25 km) band pattern and no correlation between local slope and band orientation. Because of this, we submit that regional tectonics or gravity-driven flow down modern topography are unlikely to have played decisive roles for banded terrain formation. Instead, we observed numerous locations, where band slabs appear to have broken off and subsequently rotated, as well as “cusps” that seem to have resulted from buckling. Based on this, we suggest that the banded terrain experienced both, ductile deformation as well as brittle failure on or near the surface. Despite certain similarities, neither salt (as salt glaciers), lava sheets, or land-based glaciers are in agreement with the extensive curvilinear texture and topographic/geologic setting of the banded terrain. Ice shelf margins, on the other hand, can produce surface textures akin to the banded terrain in both form and scale, even including cusps and broken off, rotated blocks. However, an ice-covered sea between 1.9 and 3.7 Ga ago is not indicated by the geologic inventory of the Hellas basin, which previous investigations found to lack any landforms indicative of a standing body of water. Instead, we identified several sinuous ridges terminating at plains covered by smaller, braiding ridges, which we interpret as eskers and glacial sandurs, respectively. As both are embayed and partially covered by the banded terrain, we tentatively propose an alternative, subglacial model of the banded terrain having formed as wet till that was viscously deformed according to the stress fields created by the ice overburden pressure in conjunction with bed topography. Although this formation model remains inconclusive, it is in agreement with climate models suggesting obliquity excursions and a denser, early Amazonian atmosphere to have caused ice accumulation in the adjacent northwestern Hellas basin rim, thus potentially enabling flow onto the floor entailing subglacial banded terrain formation.

En el NW de Burgos (España) la unidad geomorfológica de las Loras es un espacio de transición entre la Montaña Cantábrica y las llanuras de Castilla. Su relieve es morfoestructural. Alternan elevaciones, llamadas loras (sinclinales colgados de culminación plana) y valles (combes labradas en los anticlinales). La estructura es de relieve plegado, pero está alterado por fallas. El paisaje es fundamentalmente geológico., The geomorphological unity of the Loras –NW of Burgos (Spain)– is a sort of transitional space from the Cantabrian mountains and the plains of the Castille. The relief is morphological- structural. Alternating elevations brain –Loras– and valleys –combes–. The topography of the region presents a mountainous terrain with folds and the faults. The Loras its wonderful geological landscape.

The Oued Gueniche plain is located in the northeastern Tunisia. It is a part of the Bizerte Neogene molassic basin, developed at the front of the Alpine chain (The Maghrebides). The subsurface structure of this area is not enough explored and was subject of controversial interpretations. Gravity and seismic data acquired in the northeast of Tunisia were used to specify the subsurface structural configuration and the formation mechanism of the Oued Gueniche plain, as well as, its relationship with the surrounding folds. A total number of 664 gravity measurements were used to define the density distributions below the surface in the study area. The complete Bouguer gravity anomaly was performed with a reduction density of 2.4 g/cm3. Bouguer anomalies range from 9.5 to 34.8 mGal, high anomalies coincide with the Oued Gueniche plain in the northwest while weak anomalies are located on the southern part of the study area. The main NE-SW anomalies are superposed to the geological structures. The power spectrum of gravity data shows that the calculated average depth to the top of regional gravity sources is approximately 4 km while that of local (or residual) sources is approximately 0.6 km. The techniques for locating the limits of anomalous structures and estimating their depths (tilt derivative (TDR), Euler deconvolution (ED) and analytical signal (AS)) were applied to the Bouguer anomaly map to further specify the underground geological characteristics. The maxima of the horizontal gradient magnitudes (MGH) of Bouguer anomalies, upward continuated at different altitudes, revealed several NE-SW and E-W trending lineaments. A three-dimensional (3D) inversion model of gravity data has been developed for the Oued Gueniche plain in order to follow the distribution of densities. In addition, the interpretation of seismic profiles indicates that the central part of this plain is marked by the diapirism of Triassic rocks. The combination of these results with those of the surface (geological map and shallow hydrogeological boreholes) has led us to propose a kinematic model of the Bizerte region since the Middle Miocene and to update the structural scheme. Then, the NE-SW major faults (e.g. the newly defined Sfaia-Metline fault) and the NW-SE secondary ones have controlled the paleogeography and the structuration of the study area.

The Loule salt diapir grew through the Jurassic and Early Cretaceous, when tight subvertical curtain folds were developed. It was then squeezed during the Alpine orogeny in the Oligocene and Miocene. This produced an intense array of brittle faults, veins and brittle–ductile shear zones through most of the diapir. The diapir exhibits more localized shear and brittle structures than any other previously described diapir. The most unusual deformation structures are ‘streaky shear vein’ zones (a new term), with an average spacing of 1 – 5 m, and usually less than 30 cm wide. They consist of a central coarse-grained halite vein surrounded by parallel zones of wispy discontinuous shale streaks and recrystallized halite. A new mechanism is proposed for the development of these zones, where repeated pulses of fluid flow have caused extensive halite recrystallization and streaking-out of unlithified mud intercalated with crystalline halite. This explains the formation of wide zones of well-aligned mud streaks (now lithified to shale), but with only small amounts of simple shear offset observed across these zones (

An examination of halokinetics and channel evolution together in a deepwater system provides an opportunity to investigate how submarine channel morphology is locally affected by rising salt domes. The study area is located in the northern Gulf of Mexico (GOM), directly off the Louisiana continental slope in a prominent salt dome region. The influence of salt growth on submarine channel evolution is relatively understudied, particularly in the GOM. Utilizing high-resolution 3D seismic and well data and seismic geomorphology techniques, a long-lived (~ 3 Myr) Plio-Pleistocene submarine channel system has been investigated to show a relationship between variable phases of salt motion and planform morphology of preserved submarine channels. Our data suggest that local salt motion acts as a driver for submarine channel evolution. During the late Pliocene, when salt moved upward at a relatively fast rate, channels show distinct entrenchment with narrow channel belts and overall less sinuosity. When salt motion slowed down at the beginning of the Pleistocene, channels aggraded rapidly with preserved levees, and moved toward an equilibrium state with the expansion of channel belt widths. As our results indicate, the rate of salt diapirism exerted a first-order control on channel location and morphology and distribution of reservoir-prone units. This study cautions against readily invoking allogenic factors (e.g., sea level and climate) in explaining changes in submarine channel behavior and associated fan sedimentation, particularly in regions with salt tectonics.

High-resolution remote-sensing imagery, seismic, well-log, magnetotelluric data, and field observations are integrated to investigate the Cenozoic salt-related structures in the western Kuqa depression (Quele area), southern Tianshan, NW China. Field observations of Oligocene to Miocene halokinetic sequences suggest early passive diapirism was developed in the Kuqa depression. More evidence also indicate that the progradation of the Paleogene Quele alluvial fan and basement steps have important controlling roles on the formation of the early salt structures. Rock salt was driven by the progradation wedge to flow basinward, then basement steps would provide resistance and hold the positions of early salt structures. On the basis of the kinematic model, it is suggested that the early Quele salt wall, which acts as a stress concentration zone, is deformed to the Quele salt nappe during the subsequent regional shortening, and controls the changes of along-strike geometries in the Quele area.

The Sivas Basin in the Central Anatolian Plateau (Turkey), which formed in the context of a foreland fold-and-thrust belt (FTB), exhibits a typical wall and basin (WAB) province characterized by symmetric minibasins separated by continuous steep-flanked walls and diapirs. Extensive fieldwork including regional and detailed local mapping of the contacts and margins of minibasins, and interpretation of a set of 2-D regional seismic lines, provide evidence for the development of a shallow evaporite level separating two generations of minibasins within the WAB province. Here beds of symmetric exposed minibasins along diapir flank are younger than minibasins observed over autochthonous evaporites. Laterally away from the WAB province, increase in wavelength of the tectonic structures suggests a deepening of the decollement level. We interpret that a shallower evaporite level developed in the form of an evaporite canopy, triggered by significant lateral shortening. The Upper Eocene-Lower Oligocene autochthonous Tuzhisar evaporite level was remobilized by the northward migrating sedimentary load and the tilting of the southern basin margin during propagation of the foreland fold-and-thrust belt. Asymmetric and symmetric primary minibasins were overrun by an allochthonous sheet forming a canopy. A second generation of salt withdrawal minibasins subsided into the allochthonous salt sheet. The polygonal pattern of the WAB province influences the growing fold-and-thrust belt system during the late stage of the secondary minibasins development. The Sivas FTB basin is the result of the interaction between fold-and-thrust belt propagation, evaporite remobilization, and interaction between evaporite flow and sedimentation in the minibasins.

The Iranian sector of the Persian Gulf is affected by more than 30 large diapiric structures triggered by the mobilization of the Infracambrian Hormuz Complex, an evaporite-rich unit that overlies Precambrian basement at the base of the sedimentary succession. Nineteen non-piercing diapirs, without any appreciable salt intrusion into the upper succession, were studied in detail and retro-deformed by the decompaction and unfolding of 13 seismic horizons that were identified by the interpretation of a dense grid of 2D seismic lines and calibrated by well data. Salt uplift had begun by the Early Palaeozoic and persists to the present day, with major pulses of intensity during the Middle Triassic, Cenomanian, Late Oligocene, and post-Middle Miocene. The structural reconstructions and the analysis of the progressive deformation of the study diapirs do not show any link between diapiric uplift and local tectonic structures, and no clear correlation with the regional geodynamic events acting at the boundary of the Arabian plate. On the contrary, the salt uplift seems strongly influenced by the differential rate of sedimentation that affected the whole study basin (more than 40,000 km 2 ), with a coefficient of correlation between the salt uplift rate and the differential rate of sedimentation (expressed by the standard deviation of the sedimentation rate calculated over the entire basin) of 0.95. This downbuilding mechanism of diapiric growth is apparently induced by differential sedimentation over long distances (several tens of kilometers), showing that the flow of salt affected the whole basin and not just the areas around the single diapiric structures.

High-quality images provided by 3D seismic surveys have transformed the interpretations of salt geometries in passive margins. Complementary field studies are needed to expand the ideas derived from seismic image interpretation. The Cotiella Basin exposes middle Coniacian–early Santonian basins developed by post-rift gravity-driven extension and passive diapirism in the proto-Atlantic Ocean. Salt-related sedimentary and structural features were preserved during the subsequent Pyrenean Orogeny, but the diapirs were squeezed to such a degree that they were completely destroyed. As a result, their influence on the development of the Cotiella Basin remains unclear. This paper presents a 3D geometric reconstruction of the extensional faults, the stratigraphic surfaces and the associated salt structures with the main objective of discussing the role of extension versus salt withdrawal. Our results indicate that the main Cotiella Basin was dominated by extensional faulting combined with along-strike salt migration, whereas the smaller Armena, Mediodia and Seira basins were mainly dominated by salt withdrawal, involving the growth of passive diapirs, salt pillows and transfer faults. This is relevant because the described structures constitute an almost unique example to study in outcrop the structural style and kinematics of structures usually found offshore.

In diapir flanks, unconformity-bounded sedimentary packages associated with gravity-driven deposits, controlled by the ratio between the rates of sediment accumulation and diapir growth can be interpreted in the context of halokinetic sequences. The Bakio Breccias Formation (Basque Country, Spain) corresponds to redeposited carbonate deposit that developed in response to the Bakio diapir growth during the Middle Albian. These deposits provide on of the rare documented example of carbonate-dominated halokinetic sequences. The Bakio Breccias Formation consists of an alternation of clast- and matrix-supported breccias, calcirudite, calcarenite and marl, deposited along the flanks of the diapir. The description and the analysis of the Bakio Breccias Formation lead to a new model for carbonate-dominated halokinetic sequences. These sequences differ from their siliciclastic counterpart because sediment accumulation rate is controlled by carbonate platform growth on the topographic relief top of the diapirs, while sediments are preferentially deposited in the mini-basins adjacent of the diapirs, in siliciclastic settings. During transgressive system tract, carbonate platform are able to keep up with the sea level rise and to aggrade on top of the diapirs, forming thick and resistant roof, which is assumed to limit the diapir growth and thus to favour the development of halokinetic sequences with low angle unconformities (wedge halokinetic sequences). During late highstand system tract deposition (and lowstand system tract if present), platform progradation results in high sediment accumulation in the adjacent depocenters, loading the autochthonous salt layer and promote diapir growth and creation of topographic relief. In addition, if the diapir roof reaches emersion, karstification of the carbonate platform top may also favour roof destruction and diapir growth. Depending on the thickness of the roof developed previously and the amplitude of the sea level fall, the halokinetic sequences with the emersion and the karstification of the carbonate platform may display high angle unconformities (hook halokinetic sequences). Furthermore, gravity-driven deposits are assumed to be more common in carbonate-dominated halokinetic sequences, compared to their siliciclastic counterparts, since carbonate platform aggradation creates steep slopes on the diapir margins, leading to the partial collapse of the margin, even when limited diapir growth occurs. The carbonate-dominated halokinetic sequence model proposed here is an important tool for the prediction of potential reservoir distribution, seal and hydrocarbon migration in flanks of salt diapirs where carbonate platform developed., The authors would like to thank the ARNT-CIFRE and Geolink (382/2008), for the funding of the Ph.D. work of Y. Poprawski.

Helped by the studies and results of previous researchers, we herein study the neotectonic of the coastal Jeffara with the input of numerous 2D reflection seismic profiles onshore, combined with Digital Elevation Model analyses (issued from SRTM) and field works. Acquired and available data were then integrated within a GIS Geodatabase, where Jerba, Zarzis and Jorf appear to be part of a N-S pull-apart basin within a NW-SE transtensive right-lateral major fault zone. Our structural geologic and geomorphologic analyses confirm and prove the presence of NNW-SSE right-lateral en-echelon tension gashes, NW-SE aligned salt diapirs, numerous active folds offsets, en-echelon folds, and so-on… They are associated with this major right-lateral NW-SE transtensive major coastal Jeffara fault zone that affect the Holocene and the Villafranchian deposits. We therefore confirm herein a new structural geodynamic Jeffara model, due to the post Lower Cretaceous northward migration of northern African to the Eurasian plates, this NW-SE transtensive fault zone is interpreted as a part of the southern branch of the eastward Sahel block extrusion toward the free Mediterranean Sea boundary. Therefore this geodynamic movement may explain the presence, offshore, of small elongated NW-SE, N-S and NE-SW transtensive basins and grabens with petroleum interest. To conclude, at the regional scale, the structural geomorphologic approach combined with both field work and 2D reflection seismic profile analyses appear to be an excellent tool to prove and confirm the NW-SE right-lateral transtensive extrusion fault zone of the coastal Jeffara.

Large-scale sediment deformation structures formed by glaciotectonic processes have been identified south of Ludington, USA. Here, several apparent clay diapirs rise from below beach level to near the top of an approximately 60 m high bluff along the eastern shore of Lake Michigan. Throughout the area, the surface topography and locations of springs indicate a complicated subsurface structure and a preferred pattern of groundwater drainage. Since public borehole information is sparse, it is not known whether the structures exposed in the bluff are true diapirs or ridges, and if the latter, what is their orientation. In this paper we present the results of field, laboratory, and modeling studies to characterize the inland extent and orientation of these deformation structures using galvanic-source electrical geophysical methods. We exploit the large electrical contrast between a sandy sedimentary layer and an underlying clayey silt sedimentary layer in which the deformation occurred. Constant-spread traverses and multi-electrode tomographic data demonstrate that at least one of the narrow structures extends a significant distance inland.

The formation of salt structures exerted a major influence on the evolution of subsidence and sedimentation patterns in the Gluckstadt Graben, which is part of the Central European Basin System and comprises a post-Permian sediment thickness of up to 11 km. Driven by regional tectonics and differential loading, large salt diapirs, salt walls and salt pillows developed. The resulting salt flow significantly influenced sediment distribution in the peripheral sinks adjacent to the salt structures and overprinted the regional subsidence patterns. In this study, we investigate the geometric and temporal evolution of salt structures and subsidence patterns in the central Gluckstadt Graben. Along a key geological cross section, the post-Permian strata were sequentially decompacted and restored in order to reconstruct the subsidence history of minibasins between the salt structures. The structural restoration reveals that subsidence of peripheral sinks and salt structure growth were initiated in Early to Middle Triassic time. From the Late Triassic to the Middle Jurassic, salt movement and salt structure growth never ceased, but were faster during periods of crustal extension. Following a phase from Late Jurassic to the end of the early Late Cretaceous, in which minor salt flow occurred, salt movement was renewed, particularly in the marginal parts of the Gluckstadt Graben. Subsidence rates and tectonic subsidence derived from backstripping of 1D profiles reveal that especially the Early Triassic and Middle Keuper times were periods of regional extension. Three specific types of salt structures and adjacent peripheral sinks could be identified: (1) Graben centre salt walls possessing deep secondary peripheral sinks on the sides facing away from the basin centre, (2) platform salt walls, whose main peripheral sinks switched multiple times from one side of the salt wall to the other, and (3) Graben edge pillows, which show only one peripheral sink facing the basin centre.

This integrated study (field observations, micropalaeontology, magnetostratigraphy, geochemistry, borehole data and seismic profiles) of the Messinian–Zanclean deposits on Zakynthos Island (Ionian Sea) focuses on the sedimentary succession recording the pre‐evaporitic phase of the Messinian salinity crisis (MSC) through the re‐establishment of the marine conditions in a transitional area between the eastern and the western Mediterranean. Two intervals are distinguished through the palaeoenvironmental reconstruction of the pre‐evaporitic Messinian in Kalamaki: (a) 6.45–6.122 Ma and (b) 6.122–5.97 Ma. Both the planktonic foraminifer and the fish assemblages indicate a cooling phase punctuated by hypersalinity episodes at around 6.05 Ma. Two evaporite units are recognized and associated with the tectonic evolution of the Kalamaki–Argassi area. The Primary Lower Gypsum (PLG) unit was deposited during the first MSC stage (5.971–5.60 Ma) in late‐Messinian marginal basins within the pre‐Apulian foreland basin and in the wedge‐top (

The Algarve Basin is a Meso-Cenozoic sedimentary basin overlying Carboniferous basement, located in the southwestern margin of the Iberian Peninsula. Its structure reveals a protracted tectonic history comprising various pulses of Mesozoic extension followed by Cenozoic compression. This work deals with the structure along the northern margin, where the Mesozoic extensional structures and Cenozoic inversion structures crop out. The strike of the extensional structures ranges from E–W to N–S, as controlled by a shift from Tethyan-dominated extension in the east to Atlantic-dominated extension in the west. Contractional structures are inverted extensional structures, following their same trends. It is argued that the thickness of the Hettangian evaporite layer exerts a strong control on the structural style throughout the basin during the extensional and inversion episodes. The basin is affected by thick-skinned deformation along the northern margin, where salt is thin or absent, basement involved fault systems and short-cut structures. Basinward, as the Hettangian salt thickens, the margin is affected by thin-skinned deformation, with listric and down-to-the-basin growth faults, diapirism and salt-cored detachment folds. The aim was to discuss the key tectonic features, the relevance of salt, and understand the nature, timing, and significance of all these structures in the regional tectonic evolution.

Mudflow gullies are well developed in offshore areas and on the upper deepwater slope. In this paper, we discuss the formation and characteristics of mudflow gullies in a gas field in the Yinggehai Basin along the northwestern South China Sea margin, and address their impacts on sand body distribution, reservoir heterogeneity, and hydrocarbon accumulation. The geological setting and sedimentary characteristics indicate that the sedimentary environment of the study intervals is located in an area between lower shore face and offshore. The gullies are several meters to a few tens of meters wide, and are filled mainly with thick mudstones interbedded with thin siltstones. Gully fills show an overall fining upward depositional trend, and exhibit a high value, low-amplitude linear GR wireline log shape. Mudflow gullies always incise the underlying sand bars or sand sheets, are overlain by offshore shales and are therefore considered to have developed in a transgressive setting. They are of three basic types, i.e., deep-, moderate- and shallow-classes according to the incision depth. The mudflows developed in offshore environment with rapidly varying topography, and deeply cut the underlying sand bars in lower shore face environment. Influenced by diapiric events, plastic mud-rich sediments were apt to slump, yielding the studied gullies. Gullies can converge to generate a lobe at front of them. In particular, during marine transgression, due to the high depositional rate of muddy sediments and tectonic activity, marine transgression offered the most favorable scenario for the development of these gullies. The mudflows also slumped down the slope into the deep water areas of the basin. Because of the incision of mudflow gullies and transgressive wave ravinement from the southeast, the pre-existing sand bars on the lower shore face were reworked by waves and oriented in a NE–SW direction, perpendicular to the east shoreline to Hainan Island. The sand bars were affected by the mudflow gullies and diapir faults, often isolated from each other, resulting in a weak sand connectivity vertically and laterally. The degree of erosion of the sand bodies by mudflows decreases with depth. In addition, diapiric activity not only induces the formation of mudflow, but also causes CO2 in the deep buried intervals to migrate into gas reservoir attached by faults. The mudflow gullies are important causes of gas reservoir compartmentalization. CO2 filling process and gully development in the area resulted in more heterogeneity than the areas without them. Therefore, mudflow gullies control not only the reservoir compartments but also the gas content in the reservoir.

The study investigated depositional model for mud-diapir controlled intra-slope basins, deepwater Niger delta, Nigeria using conventional 3D seismic data and an enhanced detection of geologic events volume. The results of the study revealed three types of seismic facies namely accretionary channel, distributary channel and lobe and drape complexes. Channels varied in both morphology and associated depositional elements and their sinuosity was found to generally reduce with decreasing age of occurrence. Six different types of reservoir elements were identified in the study area. Three reservoir elements were associated with the channel axis and the other three elements were associated with sheet deposits. Knowledge of these variations as well as identification of the different elements is necessary to a successful exploration and development plan. The depositional model generated for the study area showed repeatable and cyclic depositional processes involved in sedimentation in this type of basin. The ideal major depositional cycle was made up of mass transport deposits at the base, overlain by a distributary channel and lobe complex, overlain by an amalgamated channel complex, and capped by a drape complex. A modified depositional model referred to as the deflect-model applies to shale-diapir sub-basins in Nigeria.

Using the seismic profiles and analog modeling, this paper addresses the salt structures in the M and B blocks in the Southern Precaspian Basin. The salt structural features, the formation mechanism and the controlling factors of structural deformation are investigated and discussed systematically. The interpretation of the seismic profiles shows that typical salt-related structures include salt wall, (flip-flop) salt diapir, salt roller, salt pillow (dome), salt weld, salt withdrawal minibasin and drag structure (or drape fold). In addition, model results demonstrate that the gravity spreading driven by progradation and aggradation is probably the primary factor in controlling the formation of the salt structures in the research area. Due to the differential loading driven by progradation, passive salt diapir developed near the progradational front followed by the formation of intrasalt withdrawal minibasin bounded by two salt diapirs, and secondary reactive triangle salt diapir or salt pillow might form within the intrasalt withdrawal minibasin. Model results also indicate that the pattern of the subsalt basement has important influence on the formation and evolution of salt structures. Salt diapirs primarily developed along the margin of the subsalt uplift basement, where high shear deformation was induced by differential sedimentary loading between the uplift area and the slope area.

The Albania thrust belt consists of both internal and external tectonic zones, which are westward overthrusts with large amplitude (50–100 km), above the Apulian Patform and the South Adriatic Basin. The External Albanides are subdivided into distinct tectonic-stratigraphic units: the Kruja zone (shallow carbonate water) in the east and the Ionian zone in the west, which is represented by pelagic limestone. The Ionian zone, located between the Sazan (Pre-Apuliane) and Kruja zones, consists of three anticlinal belts: the Berati, Kurveleshi and Cika anticlinal belts. Their western margin is bordered on overthrust faults, which have produced large westward overthrusts on each of them, with amplitudes of 10–30 kms, and are utilized through a large diapir masses. Therefore, they mask perspective plays in subthrusts. The Berati anticlinal belt is the most eastern in the Ionian zone and lies mostly in the Albanian territory and partly in the Greek territory. It has a length of about 225 kms and a width 12–22 kms, and is differentiated into two sectors: the southern sector (south of the Qafa Kicoku) and the northern sector (north of the Qafa Kicoku). Understanding the evolution of evaporite tectonics is important in determining the principal features of the structural model on the Berati anticlinal belt. The changes in the lithostatic pressure on the space have a greater role in the development of evaporite tectonics, which are conditioned by the deposition thickness of the cover sediments above the evaporites and the presence of weak tectonic loops. These loops belong to the intersecting places of transverse and longitudinal fault generated since the rifting phase (T3-Cr1). Such intersecting places are the Dumrea (Albania) and Zavrohon (Greece) on the surface. We stress that evaporites are also extended over regional thrust faults of the Berati belt, helping its overthrusting westward about 20–30 km (depicted by seismic and deep wells data). The tectonic evaporite effect differs from the expansion of the Berat thrust belt. Thus, in its southern part, as a result of a diapirism that has not emerged on the surface, it is helping orogenies in developing large fan-type anticline structures (Golika, Nemercka, Mitsikeli anticlines, etc.), that have backthrusts in their eastern flank. Moreover, we encountered the presence of a carbonate massive in the middle of the Epiro-Akarnani syncline (e.g. Timfeu massive in Greece), caused by the “blind” evaporite body effect. The northern sector (north of Qafa e Kicoku), is characterized by a smaller evaporite effect, which is reflected in increasing density of the anticlinal structures on the surface units and their normal passing to each other. The Dumrea diapir is a considerable ellipsoid-shape evaporite mass outcropping with a surface area of about 210 km2 and axes 20 × 10 km. It is an ordinary diapir with a westward overthrust (20–30 km). Most oil fields in Albania are in carbonate sections (Cr2-Pg2) in the anticline structures delivered to the thrust of adjacent units. There is another new prospect of the high perspective: The carbonate structures under overthrust of different units (subthrust complex) of the Ionian zone. The subthrust in the Ionian zone is divided into three types: 1. The subthrust beneath overthrust of thrust belts. These overthrusts are related to the evaporite detachment horizon, and they mask folded structures of subthrust. 2. The subthrusts beneath the overthrusts of the anticline units. These overthrusts have a local character and they are more developed in the Kurveleshi thrust belt. 3. The subthrusts beneath the overthrusts of the tectonic zones of the orogenetic front (Ionian and Kruja Zones) above the western autochthonous (Apulian Platform and South Adriatic Basin). These structures display duplex and triplex style. Currently, the more interesting opportunity lies in the subthrust beneath the Berati thrust belt. This has a higher perspective than the other subthrusts beneath the Kurvelesh and Cika anticlinal belts. Actually, the Berati subthrust is in the processes of being the subject of a seismic survey and exploration drilling. The discovery of a new oil field in the subthrust of the Berati anticlinal belt, with drilling of the Shpiragu-2 well, which in the first test gave 800–1300 barrels (light oil with density 35–37° API) and 2–5 mmcfd gas per day, is of great importance for the entire tectonic ensemble of the Dinaric-Albanid-Hellenic. The presence of prospective structures such as the Dumrea anticline in the north and its continuation southward (the Shpiragu oil field, Molishti anticline, etc.), beneath the thrust belt, as shown by both drilling and seismic data, together with the presence of the surface structures (e.g. the Kasidhiaris, Kurenton and Thesprotikon anticlines) in Greece, shows the regional scale potential of petroleum plays. These prospects for new oil and gas discoveries constitute the object of this important paper, offering completely new ideas.

This paper reports the first interpretative field map and stable isotope geochemistry of an exhumed Miocene inlier with conical mud volcanoes in a Persian (Arabian) Gulf salt flat (sabkha). In Kuwait, the siliciclastic low-heat flow margin of the northern gulf sector produced sedimentary conditions with numerous multilayered, unstable density gradients that were highly susceptible to recording liquefaction effects. The geotechnical characteristics of the sabkhas and the effects of local seismic activity resulted in ideal conditions in marginal sediments of Kuwait Bay, well suited for the development of deformation features. Three-dimensional, pseudo-biohermal exposures exhibit ellipsoidal pillows with craters separated by fluidized channels of chaotic orientation. The size and morphology of these structures together with co-genetic mud volcanoes are strongly influenced by sedimentary factors such as density gradients and tectonic events such as localized seismic activity, which caused mixing of fluids. Diapirs emerged concurrently with syn-sedimentary deformation, and the mud injection responded to episodic seismic activity. Interpretation based on previously published reflux models such as evaporative pumping and seawater flooding of coastal sabkhas is not applicable in this case. Rather, a model of focused ascent of brine initiated by episodic seismicity is proposed. Swarms of mud volcanoes represent new abiotic sedimentary features in sabkhas, but the per-ascensum nature of the fluid offers some comparisons to siliceous hot-water vents in south-eastern Brazil.

The northern Flinders Ranges and eastern Willouran Ranges, South Australia, expose Neoproterozoic salt diapirs, salt sheets, and associated growth strata that provide a natural laboratory for testing and refining models of allochthonous salt initiation and emplacement. The diapiric Callanna Group (∼850–800 Ma) comprises a lithologically diverse assemblage of brecciated rocks that were originally interbedded with evaporites that are now absent. Using stereonet analysis to derive three-dimensional information from two-dimensional outcrops of stratal geometries flanking salt diapirs and beneath salt sheets, we evaluate 10 examples of the transition from steep diapirs to salt sheets, 3 of ramp-to-flat geometries, and 2 of flat-to-ramp transitions. Stratal geometries adjacent to feeder diapirs range from a minibasin-scale megaflap to halokinetic drape folds to high-angle truncations and appear to have no relationship to subsequent allochthonous salt development. In all cases, the transition from steep diapirs to salt sheets is abrupt and involved piston-like breakthrough of thin roof strata, which permitted salt to flow laterally. We suggest two models to explain the transition from steep diapirs to subhorizontal salt: (1) salt-top breakout, where salt rise occurs inboard of the salt flank, thereby preserving part of the roof strata beneath the sheet; and (2) salt-edge breakout, where rise occurs at the edge of the diapir with no roof preservation. Lateral emplacement of salt sheets is dependent on the interplay between the rate of salt supply to the front of the sheet and the sediment-accumulation rate. When the ratio of salt-supply rate to sediment-accumulation rate is high to moderate, thrust advance produces base-salt flats and truncation ramps, respectively. Halokinetic folds are absent because the thrust emerges at the base of the sea-floor scarp and mass-transport complexes are rare as a result of relatively low scarp relief. If the ratio is low, pinned inflation leads to drape folding of the top salt and cover into a fold ramp, with occasional slumping of the sheet and its roof and further breakout on thrust or reverse faults. In the shallow-water depositional environments of South Australia, lateral emplacement of salt sheets occurred through some combination of thrust advance, extrusive advance, and open-toed advance, with no evidence for subsalt thrust imbricates, shear zones, or continuous rubble zones. In deep-water environments, such as the northern Gulf of Mexico, thrust imbricates and rubble zones, which represent slumped carapace, are more common. The presence of slumped carapace is caused primarily by higher topographic relief related to thicker hemipelagic roofs, a lack of dissolution, and gravity-driven transport of overburden strata to the toes of large canopies.

Mineralogical, petrographic and stable isotope analyses were carried out on sediment and rock samples collected from a deep-sea cold seep province in the Paola Ridge (southeastern Tyrrhenian Sea). The results, coupled with the interpretation of the seafloor backscatter, constrained both the biogeochemical zonation and the spatial distribution of the cold seep habitats in the area. These have proved to change in depth in a range of few meters and laterallywithin narrow zones. The mud volcanoes, characterized by a high backscatter signature, are the site of vigorous gas venting and, in the subsurface, show a rapid transition from the oxic sea water interface toward the methane-sulfate transition zone in the sediments. Intermediate backscatter typifies areas where free venting is hampered by the presence of mudflows at the seafloor. These conditions favor: i) the oxidation of sulfides near the seafloor, ii) the precipitation of siderites a few meters below the seafloor and iii) the formation of sulfides deeper in the sub-seafloor. Faults are likely candidates to act as conduits for sulfates and metal oxides that juxtapose different redox environments. Siderites precipitated in the fast and low venting sites showed enrichment in δ13C and δ18O, which are compatible with their precipitation in the methanogenic zone. The heavy-oxygen isotopic compositions of the siderites are possibly related to the dissociation of gas hydrates, which have not been mapped so far by seismic data in the study area. Mud diapirism is characterized by low backscatter seafloor, large fields of pockmarks and is dissected bynormal faults. In coincidence with the normal faults, authigenic calcites and aragonites are present at or very close to the seafloor. They have the typical isotopic signature indicating formation during sulfate-dependent microbially-mediated anaerobic oxidation of methane.They are associated with Lucinoma borealis, the youngest being dated 640-440 BP. This suggests that the seepage activity in the mud diapirs was likely clogged by either carbonates or activity of the faults only very recently.

The emergent salt diapirs of the east Zagros, Iran have been investigated by their structural positions. The study area is including of Zagros orogeny belt and Persian Gulf that both of them have been formed on northeastern part of Arabian plate. There are 84 emergent salt diapirs that originated from Hormuz formation with Infra-Cambrian to Cambrian age. Based on location, shape and orientation of the emergent salt domes in the east Zagros hinterland and Persian Gulf foreland basin, internal motivation forces in the salt deposits has been predominant compared to later tectonic forces. In the other words, most of the emergent salt diapirs are pre-orogenic diapirs and they had got prominent role as pines in determining the shape and location of next structures during to the Zagros orogeny. Finally, Neogene continental collision has a supplementary role to diapirism and salt reactivation. However there are an evidence to syn-orogenic emergent diapirs that they have got an important role in the progressive deformation.

The Napag is the biggest Mud Volcano at Makran in Iran. The main aim of this research is the investigation of geologic setting and geographic situation of Napag Mud Volcano as a well-known mud diapir at Makran on the south eastern margin of Iran. The Napag Mud Volcano has been formed during quaternary of as a conical hill on the flat plain in coastal region Oman Sea. There are badlands area and several mud volcanoes that they have been triggered by longitudinal normal faults. This normal faults have been developed in neotectonic regime by the roll-back of oceanic lithosphere (beneath of Oman Sea). Finally, the main characteristics of the Napag mud diapir are presented.