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The underground thermal fluid is one of the significant factors controlling the formation and quality of reservoirs. The Huangliu Formation (N1h) in YF1 area of the central depression belt in the Yinggehai Basin, South China Sea, is characterized by intense thermal fluid activities related to mud diapir and large-scale shallow-water gravity flow deposits. The multi-episodic invasion of high-temperature and CO2-rich thermal fluid into the formation induces complex water-rock reaction during diagenetic process, providing a preferable investigation opportunity for revealing how thermal fluid affects reservoir quality. This study characterizes the reservoirs in the formation through core and thin section analyses as well as physical property test. The reservoirs are dominated by fine-grained sandstone characterized by medium porosity (15.2–21.3%) and lower permeability (0.56–15.75mD). Based on an analysis of casting thin section, cathode luminescence (CL), scanning electron microscope (SEM), carbon and oxygen isotope, inclusion test, and electron-probe microanalysis (EPMA), we systematically investigate the diagenetic patterns and pore evolution process for the reservoirs in the formation. The episodic invasion of thermal fluid occurred approximately 0.4 Ma ago plays an important role in controlling reservoir development: The CO2-rich formation water induces massive late-stage dissolution, resulting in a higher proportion of dissolved pores (38.7–46.4%), which improves the porosity of reservoirs at a depth of 2600–3100 m. Nevertheless, the late dissolution together with carbonate cementation occurred in closed diagenetic system blocks most seepage channels. Furthermore, the relatively high level clay mineral transformation in the YF1 area leads to a higher content of authigenic illite (44–62%) in the formation. Massive authigenic illite severely blocks the pore throats in fine sandstone, reducing permeability. This study offers an insight to the understanding of mud diapir-derived thermal fluid affecting and controlling the quality of reservoirs in some areas of the Yinggehai Basin.

This study comprises the investigation of the complex and deformed Late Pleistocene sedimentary sequence in western Latvia composed of sandy sediments that are protruded by large-scale clayey silt diapirs and covered by glaciotectonically disturbed discontinuous patches of the Late Weichselian till. We use detailed measurements by ground-penetrating radar (GPR) and electrical resistivity tomography (ERT) combined with borehole data and sedimentological investigations at the Baltic Sea cliffs to map and characterize the large-scale deformation structures and discontinuous till patches. We distinguish the intriguing and previously not detected characteristics of the spatial distribution pattern of discontinuous till layer represented as elongated, up to 150 m long and up to 50 m wide patches, parallel to the seacoast and perpendicular to the latest ice flow direction. The upper surface of till patches is flat and not inclined in any direction that is partially explainable by the postglacial erosion of the Baltic Ice Lake. The possible locations of diapirs inland are drawn from GPR data. We relate the formation of observed large-scale deformations to subglacial diapirism induced by the ice loading of the advancing Apriķi Ice Tongue: clayey silt sediments become loaded and overpressurized, and flowed upwards intruding into the overlying sandy sediments. The initial deposition and deformation of till layer could have been affected by the diapirism process and preferred accretion of till in inter diapir spaces. We demonstrate that the geophysical methods can greatly supplement traditional geological investigations in the field revealing characteristics of deformed sediment sequences that are not recognizable from the outcrop data only and thus can have significant implications on the interpretation of deformation processes.

A petroleum trap is “the place where oil and gas are barred from further movement” (Levorsen, 1967). The highest point of the trap is called the crest, or culmination. The lowest point at which hydrocarbons may be contained in the trap is called the spill point, this lies on a horizontal contour, the spill plane. The vertical distance from the crest to a spill plane is the closure of the trap. A trap may contain oil, gas, or both. The oil:water contact is the deepest level of producible oil. Some oil fields have a layer of heavy oil, termed a tar mat, at the oil:water contact. Tar mats impede the flow of water into a reservoir when petroleum is produced. Fluid contacts in a trap are generally planar, but some are tilted. The cause of the tilting can be either hydrodynamic flow, production, or a change in facies. A change in grain size across a reservoir causes a tilted contact. Seals are impermeable rock. Shales are the commonest seal, but evaporate the most effective. Traps may be classified as structural, diapiric, stratigraphic, hydrodynamic, or combination. Structural traps consist of anticlinal, compactional, and fault and fault-related. Diapiric traps include salt domes and mud diapirs. Stratigraphic traps include those related to unconformities, channels, barrier bars, pinchouts, reefs, and diagenetic. In hydrodynamic traps, downdip movement of water is essential to prevent the upward movement of oil and gas. Many oil and gas fields around the world are not due solely to structure or stratigraphy or hydrodynamic flow, but to a combination of two or more of these forces. Such fields are termed combination traps. Timing of trap development relative to petroleum migration is important. If traps predate migration, they will probably be productive.

Salt formations exist in Kızılırmak Graben (Central Anatolia, Turkey), which consists of volcano-sedimentary units, and it was stated in previous studies that these formations have a diapiric structure. The adjacent basin, Ayhan Basin, contains bituminous shale and operated coal deposits. For this reason, in this study, it is aimed to investigate the oil and gas potential of the Kızılırmak Graben by conducting TPH (Total Petroleum Hydrocarbons) analysis on the samples taken from natural cold-water resources by making use of the thought that hydrocarbon generation may come into existence from those units in the Ayhan basin. As a consequence of the analyses performed, hydrocarbons have been brought into the open in all the water samples. The organic geochemical methods have been used to find out the source of hydrocarbons determined in the water resources. The disclosed n-alkane hydrocarbons are the mature petroleum hydrocarbons derived from peat/coal type organic matter (Type III kerogen, gas-prone). These mature hydrocarbon-rich waters can be regarded as evidence for the availability of a working hydrocarbon system associated with possible salt diapir identified by using gravity and magnetic data obtained from the investigation area.

Rock salt has high thermal conductivity (>6 W m−1 K−1 at 20 °C) compared to most overlying and adjacent sedimentary rocks, resulting in a thermal blanket effect and a favorable play for low enthalpy geothermal resources. However, the effect of temperature on rock salt thermal conductivity is greater than most other rocks. The result can be a reduction in this contrast between rock types, which has implications for geothermal exploration. The temperature dependence of rock salt thermal conductivity was shown to be a critical factor in our geothermal potential assessment of the Magdalen Islands (Canada). We evaluated the subsurface temperature of this archipelago using numerical simulations of conductive heat transfer, specifying a bulk thermal conductivity of rocks that varies with temperature and porosity, and the latter varying with pressure. A steep geothermal gradient, locally exceeding 40 °C km−1, was found in layers overlying shallow salt domes at depths of ∼1 km but not over a deeper dome due to low thermal conductivity contrasts. This finding highlights the effect of temperature on rock salt thermal conductivity, which should be considered when assessing the geothermal potential of salt domes, intrusions or diapirs, to avoid overestimating the subsurface temperature.

Soft-sediment deformation structures (SSDSs) are widely developed in the lacustrine sediments of paleo-dammed lakes in tectonically active regions and contain a wealth of information on regional fault activity. In this study, multiple SSDSs (load structures, small-scale slump structures, droplets, diapir and pillow structures, silty-clay pillars and large-scale slump structures) were identified in the strata of the Late Pleistocene lacustrine sediments in the Tashkorgan River drainage in northeastern Pamir. The deformation mechanisms of the SSDSs were related to the liquefaction, fluidization and thixotropic behaviors. The regional tectonic settings and SSDS features point toward a trigger mechanism with seismic activities and indicate that the seismogenic faults were possibly related to the southern part of the Kongur Shan extensional system. Accelerator mass spectrometry (AMS) radiocarbon dating data showed that the SSDSs in the Tashkorgan lacustrine sediments formed 30,221-29,932 cal BP and 25,825-25,317 cal BP. The results of this study improve our understanding of fault activity and geodynamic processes in northeastern Pamir during the Late Pleistocene.

The flood basalts of large igneous provinces (LIPs) are fed by a vast and often complicated plumbing system that can include giant dyke swarms, sill complexes, mid- to upper-crustal intrusive complexes, lower-crustal intrusions and a magmatic underplate at the base of the crust. In this study, we focus on the role of two poorly understood and little studied components of LIP plumbing systems: giant circumferential dyke swarms and mid-crustal igneous complexes. Giant circumferential dyke swarms, which have only recently been recognized, are often associated with giant radiating dyke swarms, whose foci are located at or near the centres of the circumferential swarms. The giant radiating swarms are usually interpreted to be generated during domal uplift above a mantle plume. We compare giant circumferential dyke swarms, giant radiating dyke swarms and coupled circumferential-radiating dyke systems with possible analogues on Venus, called coronae, novae and corona-nova systems, respectively. Coronae are large tectonomagmatic features that typically include a quasi-circular/elliptical annulus of graben that are thought to be underlain by dykes. Novae are large radiating graben systems that are also thought to be underlain by dykes. Coronae, novae and coupled corona-nova systems are usually interpreted to be generated above mantle plumes or diapirs. In addition, we discuss the potential importance of mid-crustal intrusive complexes in LIP plumbing systems, especially those that may be circumferential to plume centres. Given their location, they could act as feeders to either giant radiating or giant circumferential dyke swarms, or both.

Studying deep-water cold seep systems is of great significance to gas hydrate exploration due to their close relationship. Various cold seep systems and related gas hydrate accumulations have been discovered in the northern South China Sea in the past three decades. Based on high-resolution seismic data, subbottom profiles, in situ submergence observations, deep drilling and coring, and hydrate gas geochemical analyses, the geological and geophysical characteristics of these cold seep systems and their associated gas hydrate accumulations in the Qiongdongnan Basin, the Shenhu area, the Dongsha area, and the Taixinan Basin have been investigated. Cold seep systems are present in diverse stages of evolution and exhibit various seabed microgeomorphic, geological, and geochemical features. Active cold seep systems with a large amount of gas leakage, gas plumes, and microbial communities and inactive cold seep systems with authigenic carbonate pavements are related to the variable intensity of the gas-bearing fluid, which is usually derived from the deep strata through mud diapirs, mud volcanoes, gas chimneys, and faults. Gas hydrates are usually precipitated in cold seep vents and deeper vertical fluid migration pathways, indicating that deep gas-bearing fluid activities control the formation and accumulation of gas hydrates. The hydrocarbons collected from cold seep systems and their associated gas hydrate reservoirs are generally mixtures of biogenic gas and thermogenic gas, the origin of which is generally consistent with that of deep conventional gas. We also discuss the paragenetic relationship between the gas-bearing fluid and the seafloor morphology of cold seeps and the deep-shallow coupling of gas hydrates, cold seeps, and deep petroleum reservoirs. It is reasonable to conclude that the deep petroleum systems and gas-bearing fluid activity jointly control the development of cold seep systems and the accumulation of gas hydrates in the northern South China Sea. Therefore, the favorable areas for conventional oil and gas enrichment are also prospective areas for exploring active cold seeps and gas hydrates.

The Kimmeridgian Alcobaça Formation of the Lusitanian Basin forms a mixed carbonate–siliciclastic unit between basinal deposits of the Abadia Formation, and fluvial–terrestrial strata of the Lourinhã Formation. This study presents >2.5 km of detailed logs of nine outcrop sections of the Alcobaça Formation in its type region. Eight of these sections encircle the Caldas da Rainha Diapir, which was a prominent, emergent, passive salt diapir during the time of deposition. Palaeoenvironments of the unit form a complex mosaic of low- to high-energy, carbonate- or siliciclastic-dominated shallow shelf settings; coastal embayments and lagoons; and coastal plains with rivers, lakes and playas. In the strata, abundant microfauna is often joined by a rich macrofauna, usually dominated by bivalves. Locally, corals, calcareous sponges or oysters form meadows or patch reefs. These autochthonous to parautochthonous remnants of former communities are assigned to 35 benthic macrofaunal associations. The integration of palaeoecological analysis of these associations with microfaunal and sedimentological data provides constraint on their salinity ranges, which range from slightly hypersaline to freshwater. Frequent temporal and spatial salinity fluctuations are attributed to variations in relative sea-level, salt tectonics or climate. The NNE-trending Caldas da Rainha Diapir induced pronounced facies differentiation. Predominantly, non-marine siliciclastic facies in the northwest and carbonate to siliciclastic, marine to brackish facies in the southwest are contrasted by shallow-marine carbonate facies east of the diapir. Comprehensive exposure and well-preserved fossils make the Alcobaça Formation an excellent showcase to demonstrate how biofacies analysis can help to disentangle the interplay of climate changes, sea-level fluctuations and salt tectonics. Based on the improved characterisation of the unit, the Alcobaça Formation is formally defined, and seven members are established.

Fluid systems in inverted rifted margins are challenging to interpret because fractures formed before compression were often reactivated acting as fluid pathways as new ones formed. Deciphering the fracture and fluid flow history in such complex settings has key implications for the prediction of the distribution of mineral resources. As an example, we reconstruct the fluid flow evolution of a portion of the inverted Pyrenean rift, the Upper Pedraforca thrust sheet, from the Mesozoic extension to the Alpine orogeny. We combine structural analysis and petrographic, geochemical and geochronological data obtained from 87 samples of fracture-filling carbonate cements. During the Late Jurassic-Early Cretaceous, low-temperature seawater produced dolomitization of Jurassic and Lower Cretaceous limestones in an extensional setting. During the Early Cretaceous salt-related extension, formation waters, probably evolved seawater or fluids that interacted with Triassic evaporites, at temperatures from 125 to 149°C migrated through fractures. The formation of breccias within post-salt rocks in primary weld zones facilitated the upward migration of formation waters that interacted with pre-salt rocks with high 87Sr/86Sr ratios. Formation waters at temperatures of 80°C migrated during the emplacement of the Upper Pedraforca thrust sheet in the Late Cretaceous-Palaeocene. These fluids interacted with Upper Cretaceous Carbonates and/or Triassic evaporites. In contrast, the influence of meteoric fluids increased in shallower positions due to the exhumation of the SE Pyrenees during the Eocene-Oligocene. Coevally, hot dolomitizing fluids migrated along diapir walls during the formation of secondary welds. Supergene ores documented in diapiric areas worldwide related to meteoric fluids, and the similar meteoric percolation occurred in the Upper Pedraforca thrust sheet, suggest that supergene mineralization could be found in the Pyrenees. Brecciation of rocks in primary weld zones and evaporite detachments, where mineralization accumulate in fractures from basement-derived fluids, also suggests that similar ores could be found in the Pyrenees., This research was performed within the framework of DGICYT Spanish Project PGC2018-093903-B-C22 Ministerio de Ciencia, Innovación y Universidades/Agencia Estatal de Investigación/Fondo Europeo de Desarrollo Regional, Unión Europea, SUBTETIS (PIE-CSIC-201830E039), ALORBE (PIE-CSIC-202030E310) and Grup Consolidat de Recerca ”Geologia Sedimentària” (2017SGR-824) and Generalitat de Catalunya, Grant/Award Number AGAUR 2017SGR-847. The isotopic analyses were carried out at “Centres Científics i Tecnològics” of the Universitat de Barcelona. Strontium analyses were done at the “CAI de Geocronología y Geoquímica Isotópica” of the Universidad Complutense de Madrid. The high resolution inductively coupled plasma-mass spectrometry analyses were carried out at labGEOTOP of the GEO3BCN-CSIC, a cofounded structure by FEDER-UE (Ref. CSIC08-4E-001). The clumped isotopes analyses were performed in the Qatar Stable Isotope Laboratory of Imperial College of London. E.G.R. acknowledges the Spanish Ministry of Science, Innovation and Universities for the “Ramón y Cajal” fellowship RYC2018-026335-I.

—The paper is devoted to the identification and study of active neotectonic structures using a formalized (computerized) analysis of linear elements (lineaments) in the southern part of the junction of the Siberian Platform with the Baikal Rift Zone (BRZ). The time-varying movements of the Amurian subplate, the development of the mantle diapir, and the remote effect of the Indo-Eurasian collision combine to determine structure formation and neotectonic activity of the study region. The geodynamic features of the region are reflected in the system of small and extended lineaments. The issue is considered on the regional and local scale levels. Some details of the method and interpretation of the results are discussed. It is shown that a statistical relationship exists between the parameters of lineament formal identification in satellite images and kinematics and activation age of the corresponding Cenozoic faults. The lineament analysis (LESSA technology) is used to assess the effect of BRZ tectonic stresses on the Pliocene-Quaternary movements of the southern part of the Siberian Platform and on the formation of morphostructures in the region. The stages of stress-state evolution, fault activity, terrain formation, and some geodynamic models of the development of the Baikal region are discussed.

Classic models of gravity-driven salt tectonics commonly depict kinematically-linked zones of overburden deformation, characterised by updip extension and downdip contraction, separated by a weakly deformed zone associated with downdip translation above a relatively smooth base-salt surface. We use 2D and 3D seismic reflection and borehole data from the south-central Campos Basin to show that these models fail to adequately capture the complex range of structural styles forming during salt-detached gravity-driven deformation above a rugose base-salt surface. In the Campos Basin the base-salt is defined by broadly NE-trending, margin-parallel, generally seaward-dipping ramps that have up to 2 km of structural relief. We define three domains of overburden deformation: an updip extensional domain, an intermediate multiphase domain, and a downdip contractional domain. The multiphase domain is defined by large, partly fault-bounded, ramp-syncline basins, the stratigraphic record of which suggest c. 28 km of seaward gravity-driven translation of salt and its overburden since the end of the Albian. We also identify three main types of salt structures in the multiphase domain: (i) contractional anticlines that were subjected to later extension and normal faulting; (ii) passive-to-active diapirs that were later extended and widened, and which are bound on their landward margins by landward-dipping, salt-detached normal faults; and (iii) reactive (extensional) diapirs that were subsequently squeezed. We argue that this multiphase deformation occurs because of basinward translation of salt and its overburden over complex base-salt relief, consistent with the predictions of physical models and several other seismic reflection data-based studies. Critically, these complex local strains overprint margin-scale patterns of deformation.

—The paper considers the seismogeologic, structural, and tectonic features of Neoproterozoic–Paleozoic and Mesozoic sedimentary complexes in the Arctic regions of the Siberian Platform. Based on the results of deep drilling, the geologic structure of the study area was analyzed, and the key sections of Neoproterozoic–Paleozoic deposits of the Anabar–Khatanga and Lena–Anabar oil and gas areas (OGA) were compiled. Analysis of geological and geophysical materials showed the existence of a sedimentary basin up to 14–16 km in thickness on the continental margin of the Siberian Platform, with five regional seismogeologic megacomplexes in its section: Riphean, Vendian, lower–middle Paleozoic, Permian, and Mesozoic. Based on the results of a complex interpretation of CDP seismic-survey and deep-drilling data, a structural and tectonic analysis was performed, structural maps were compiled for all reference stratigraphic levels, and a conclusion has been drawn about the similarity of the structural plans of the Riphean top and overlying sedimentary complexes. Using a structural map along the Permian top, a tectonic map of the study area was compiled, which corresponds to the current state of study. The results of numerical modeling of the salt diapir formation processes are presented, and the types of anticlinal structures, potential oil- and gas-promising objects, are considered.

Seismic characteristics of mud diapir has been investigate over an area of 3900 km2, located in the central part of Song Hong basin, using four 2D seismic lines. There are six mud diapirs and three mud pipes have been documented. The core of the diapir is characterized as a zone of chaotic, disrupted seismic reflection, with the amplitude reflection ranging from low the high. High amplitude reflections are distributed in the top of the some diapir, which is possibly related to the gas accumulation. They are in different sizes, shapes, and the relationship with surrounding rock. They are characterized as deep sourced, high energy rooting from Oligocene/early Miocene shale layers. This organic rich shale rocks are in the oil and gas windows, thus their hydrocarbon generation combining with the tectonic inversion during Miocene make the overpressured shale and therefore rising the diaipirs. The area has experienced several phases of eruption in Middle Miocene, Late Miocene, Late Pliocene and Present day. The discovery and identification of the occurrence of mud diapirs implied a great potential for prediction of structural traps in the central part of the Red River Basin.

Subsurface salt flow can deform overlying strata and influence contemporaneous sedimentary processes. Studying salt-sediment interactions is challenging in the subsurface due to poor imaging adjacent to salt, and in the field due to the dissolution of halite. Discrete Element Modelling provides an efficient and inexpensive tool to model stratigraphy and deformation around salt structures, which is advantageous over other modelling techniques as it realistically recreates brittle processes such as faulting. Six 2D experiments were run representing 4.6 Myr (46,000 timesteps) to determine the effect of salt growth on syn-kinematic stratigraphy. Halokinetic deformation of stratigraphic architecture was assessed by varying sediment input rates (slow, intermediate, and fast), and increasing and decreasing them through time. Results show the realistic formation and evolution of salt-related faults which define a zone of halokinetic influence, ~3 times the width of the initial diapir. Outside of this, pre- and syn-kinematic stratigraphy are undeformed. Within this zone, syn-kinematic strata are initially isolated into primary salt withdrawal basins, onlapping and thinning towards the salt-cored high. In most models, syn-kinematic strata eventually thin across and cover the diapir roof. Thinning rates are up to six times greater within 350 metres of the diapir, compared to further afield, and typically decrease upwards (with time) and laterally (with distance) from the diapir. Outputs are compared to a subsurface example from the Pierce field, UK North Sea, which highlights the importance of considering local fluctuations in diapir rise rate. These can create stratigraphic architectures that may erroneously be interpreted to represent ‘apparent’ increases/decreases in sedimentation rate. Exposed examples, such as the Bakio diapir, northern Spain, can be used to make inferences of the expected depositional facies, below model resolution. Our models aid prediction of sedimentary unit thickness and thinning rates, and can be used to test interpretations arising from incomplete or low-resolution subsurface and outcrop data when building geological models for subsurface energy.

The implementation of satellite geological investigations within the continent–Sea of Japan transition zone in Southern Primorye has made it possible to establish series, connected with faults, of rows (chains) of Miocene and Miocene–Pliocene volcanic structures and large fracture zones, which extended over the continental slope from the shelf to Central Basin of the Sea of Japan. They are structural markers, the steady strike of which calls into question tectonic formation models of the Sea of Japan Basin, based on large-scale horizontal movements of crustal blocks. The combination of linear systems of small monogenic volcanic structures and fissure eruptions of basalt lava reflects the multioutlet nature of Central Basin volcanism, which occurred due to the rather shallow location of asthenospheric highs or mantle diapirs. It is suggested that the formation and relatively rapid subsidence of this basin is related to active mantle defluidization, with large-scale basalt volcanism and injections of deep mafic and ultramafic material that replaced rocks of the continental crust.

The interactions between salt diapirs, thrust welds and thrusts in contractional belts are poorly understood due to, first, the inability of seismic data to distinguish between thrusts and welds or resolve associated sub-resolution deformation, and second, the paucity of good field examples. The Warraweena area in the Northern Flinders Ranges of South Australia contains examples of Neoproterozoic to Early Cambrian squeezed diapirs linked by steep reverse faults formed during the Delamerian Orogeny. Benefiting from good field exposures, we use geological mapping, cross-section construction and conceptual structural models to assess the three-dimensional geometry and evolution of the structures, the lateral transition from diapirs to linking faults and the variability of associated meso- and small-scale deformation. Three discrete diapirs consist of narrow outcrops of Callanna Group megabreccia (Willouran in age) up to 5-km long. Their diapiric origin is confirmed by local development of caprock, steepening of flanking strata in composite halokinetic sequences and reworked diapir and roof debris in adjacent strata. The surrounding rocks display only background levels of small-scale deformation. In contrast, the linking faults show no evidence of precursor diapirism, have fault-related anticlines up to 100s of m in wavelength in their hanging walls, and an associated increase in small-scale deformation (i.e. millimetre to metre scale folds, fractures and shear fabrics). The transitions from diapirs to faults occur within less than 200 m as short thrust welds at the diapir terminations. The exposed structures are analogous to those found on the subsurface of other salt basins such as the Gulf of Mexico and the South Atlantic conjugate margins. The results of this work can aid geoscientists evaluating three-way traps against squeezed diapirs, welds or faults, and can help them to predict the style and abundance of both halokinetic and small-scale structures that are below seismic resolution.

Mud volcanoes and diapirs are geological structures formed due to arch piercing or diapiric intrusion of ductile sedimentary materials into the overlying strata along high permeability channels. A detailed study on the processes controlling the formation of mud volcanoes and diapirs in the northern continental margin of the South China Sea is of vital importance to the exploration of economically viable oil and gas reservoirs and can be helpful to the exploration of natural gas hydrate in a sedimentary basin. The fluid seepage structures that occur in the Mesozoic and Cenozoic sedimentary basins of the northern South China Sea show significant differences in their morphological and tectono-structural characteristics. We used high-resolution seismic profiles and instantaneous frequency profiles to understand the mechanisms that are critical with respect to the differential development of the investigated piercement structures. Differences in stress field do not directly lead to the difference in the scale of mud volcanoes or diapirs. Fractures may play an important role in the formation of mud volcanoes and diapirs. The thickness of the sediment was found to have a strong impact on the formation of fluid leakage structures that thicker sediments are more conducive to the development of mud diapirs and the thinner one is more likely to form mud volcanoes.

The main objective of this study is to detect the subsurface extension of salt diapirs and structural deformations in the city of Jazan and its suburbs using gravity data. Salt diapirs are of economic importance, but they can also be geologic hazards. Our results show weak Bouguer anomalies at Jazan Port and Jazan Heritage Village, suggesting the intrusion of near-surface salt diapirs. These anomalies are not observed in regional gravity maps, indicating shallow depths of the interpreted salt diapirs. Edge-detection gravity maps clearly reveal that NW–SE and NE–SW trending fault systems dissect the area. The NW–SE trending faults dissect the city into a series of faults and tilted blocks that generally dip toward the Red Sea, and which are crosscut by a NE–SW transform shear zone at Jazan Heritage Village. The interpreted salt diapirs are controlled by rifting since the Miocene. It is suggested that the salt diapirs migrated vertically through the walls of NW-trending fault blocks to reach the surface in the old city of Jazan. The salt diapirs extend eastward, facilitated by lateral movement along the NE transform fault until they are stopped by the NW-trending uplifted blocks in the western side of the city. The interpreted halokinesys and faulting structures may be a potential geotechnical hazard that could affect the infrastructure and urban buildings in Jazan and its suburbs.

Plate tectonics drives variation in sea-level, over intervals of approximately107–108years. These variations may have significant effects on the pace of (biological) evolution through the elimination of terrestrial niches and the expansion of shallow-water marine niches. However, within the solar system, only the Earth experiences this kind of tectonism. Venus displays regional tectonism, characterized by rising diapirs within the plastic mantle. Impinging on the lithosphere, these plumes produce a range of structures of varying dimensions; the uplift of which would raise sea-level, were Venus to have oceans. Using Magellan observations of Venus, we model the impact of regional tectonism on sea-level for given areas of Venusian ocean, then compare the effect with terrestrial tectonic processes for similar oceanic area. We show that despite variation in the geographical extent of Venusian-style tectonic processes, the styles of regional tectonism on Venus can produce the same order of magnitude changes in sea-level, for a given area of ocean, as plate tectonics. Consequently, we examine some of the impacts of marine transgression on habitability and the evolution of life.

3D post-stack time migrated seismic data and a suite of composite well log data from six wells drilled within the “AFUN” field Niger delta were used to effect a detailed interpretation of the field. This was with a view to delineating architectural elements that control reservoir quality of a deepwater turbidite reservoir. The data analyses were done using the Petrel software. LAS file of logs were imported into the Petrel software as well as SEG.Y. seismic data. Fault interpretation and horizon mapping were based on the well-seismic tie from the generated seismogram. Time and depth structure maps were created. Thirty faults which include growth faults, reverse faults, collapsed crest structure and as well as faults that are synthetic and antithetic to the growth faults were mapped. The growth faults are believed to act as pathways for the updip movement of hydrocarbon from the Akata Formation to Agbada Formation. The structural interpretation showed that the area has been subjected to compressional deformation which resulted in reverse faulting system in toe thrust zone influenced by shale diapirs. The maps revealed contour closures that belong to an anticlinal structure which is forming traps in the reservoirs. The structures are faulted North-South trending rollover anticlines. It has also been shown that the distribution and type of architectural elements i.e. fractures within the fan system have major impact upon the reservoir distribution, continuity and connectivity of sand/shale bodies. The study concluded that structural style and facies architecture are the two fundamental elements that defined the reservoir heterogeneity of the “AFUN” Field.

Although some giant gas fields found in the deepwater area of the Qiongdongnan Basin (QDNB), China, are often associated with mud diapirs and/or gas chimneys, no comprehensive 3D work has been undertaken to characterize them. We have conducted a 3D seismic investigation using the root-mean square, coherence, and instantaneous frequency attributes to provide a better understanding of the conduit systems in the QDNB. The results show that the conduit system that we investigated can be separated vertically into four zones in the following order: (1) a structurally diapiric weak zone at the base, followed by (2) an injected or reinjected sandstones zone, (3) a gas chimney zone, and (4) a mud volcanic zone at the top. The morphology of the structurally weak zone is elliptical, formed by the intersection of northwest–southeast- and nearly east–west-trending tectonic faults. We infer that this zone provides pathways for the ascent of the diapiric mud that was probably sourced by the underlying overpressured mudstones. The injected or reinjected sandstones zone is characterized by high amplitude anomalies, and it was probably fed by the lobes of underlying submarine fans. The gas chimney zone, which is characterized by low frequencies and weak amplitudes, is probably composed of a mixture of uprising mud and free gas formed from the underlying overpressured mudstones, whereas the mud volcano with a Christmas-tree pattern and is composed of a central crater, the southern flank of which is a mudflow, formed when the uprising mud migrating upward through faults got to the paleo seafloor. Finally, we have developed schematic illustrations that would aid in understanding the different stages of the formation and internal architecture of this conduit system.

Many sedimentary basins host thick evaporite (salt) deposits. Some of these basins also host extensive igneous intrusion networks. It thus seems inevitable that, in some locations, magma will interact with salt. Yet how interaction between these materials may influence salt tectonics or magma emplacement, particularly at the basin-scale, remains poorly understood. We use 3D seismic reflection data from the Santos Basin, offshore Brazil to image 38 igneous intrusions spatially related to thick Aptian salt. Based on identified seismic–stratigraphic relationships, we suggest sill emplacement likely occurred during the late Albian-to-Santonian. We show intra-salt sills are geometrically similar to but laterally offset from supra-salt sills. We suggest ascending magma was arrested by the salt in some areas, but not others, perhaps due to differences in evaporite lithology. Our mapping also reveals most sills occur within and above the presalt Merluza Graben, an area characterized by Albian-to-Neogene, salt-detached extension. In adjacent areas, where there are few intrusions, salt deformation was driven by post-Santonian diapir rise. We suggest emplacement of hot magma within evaporites above the Merluza Graben enhanced Albian-to-Santonian salt movement, but that crystallization of the intrusion network restricted post-Santonian diapirism. Our work indicates salt–magma interaction can influence salt tectonics, as well as the distribution of magma plumbing systems, and thus could impact basin evolution.

With many types of salt structures developed in the Lower Cretaceous Aptian Formation, the passive continental marginal basins in the middle segment of the south Atlantic are hot areas of deep-water petroleum exploration. Based on analysis of differential deformations of salt structures, the influences of the inclination of subsalt slope, subsalt topographic reliefs and basement uplifting on the formation of salt structures were analyzed by physical modeling in this work. The experimental results show that the subsalt slopes in the middle West Africa basins are steeper, so the salt rock is likely to rapidly flow towards the ocean to form larger and fewer salt diapirs. In the Santos and Campos basins, the basement uplifts outside the basins are far from the provenances, which is conducive to the intrusion and accumulation of salt rock on the top of the basement uplifts. In contrast, in the middle West Africa, the basement uplifts are close to the basin margin, the residual salt layers above them are thin, and small triangular salt structures develop on both sides of the uplifts. Moreover, the uplifting of the African plate is also conducive to the full development of salt diapirs in the middle West Africa and results in large-scale thrust faults and folds in the front compressional zone.

Behavior of sediment gravity flows can be influenced by seafloor topography associated with salt structures; this can modify the depositional architecture of deep-water sedimentary systems. Typically, salt-influenced deep-water successions are poorly imaged in seismic reflection data, and exhumed systems are rare, hence the detailed sedimentology and stratigraphic architecture of these systems remains poorly understood.The exhumed Triassic (Keuper) Bakio and Guernica salt bodies in the Basque–Cantabrian Basin, Spain, were active during deep-water sedimentation. The salt diapirs grew reactively, then passively, during the Aptian–Albian, and are flanked by deep-water carbonate (Aptian–earliest Albian Urgonian Group) and siliciclastic (middle Albian–Cenomanian Black Flysch Group) successions. The study compares the depositional systems in two salt-influenced minibasins, confined (Sollube basin) and partially confined (Jata basin) by actively growing salt diapirs, comparable to salt-influenced minibasins in the subsurface. The presence of a well-exposed halokinetic sequence, with progressive rotation of bedding, beds that pinch out towards topography, soft-sediment deformation, variable paleocurrents, and intercalated debrites indicate that salt grew during deposition. Overall, the Black Flysch Group coarsens and thickens upwards in response to regional axial progradation, which is modulated by laterally derived debrites from halokinetic slopes. The variation in type and number of debrites in the Sollube and Jata basins indicates that the basins had different tectonostratigraphic histories despite their proximity. In the Sollube basin, the routing systems were confined between the two salt structures, eventually depositing amalgamated sandstones in the basin axis. Different facies and architectures are observed in the Jata basin due to partial confinement.Exposed minibasins are individualized, and facies vary both spatially and temporally in agreement with observations from subsurface salt-influenced basins. Salt-related, active topography and the degree of confinement are shown to be important modifiers of depositional systems, resulting in facies variability, remobilization of deposits, and channelization of flows. The findings are directly applicable to the exploration and development of subsurface energy reservoirs in salt basins globally, enabling better prediction of depositional architecture in areas where seismic imaging is challenging.

Existing definitions for passive and active salt diapirism are somewhat overlapping and ambiguous. These terms are also equated to downbuilding and upbuilding, respectively, which are problematic concepts as originally conceived and even as subsequently modified. This results in conflicting usage and lack of consensus in the literature, creating confusion and decreasing the utility of the terms. For example, a diapir with a thin roof is defined as active by some but passive by others. In this short contribution, we first review historical definitions and then focus on several inherent problematic aspects including (1) the applicability of the concepts of downbuilding and upbuilding, (2) using the absence or presence and thickness of a diapir roof as criteria to classify diapirs as active or passive, and (3) the related concept of halokinetic sequences. We offer three suggestions in the hope of improving understanding and communication. First, we suggest that the terms downbuilding and upbuilding should be abandoned. Second, we argue that passive diapirism should be used sensu lato in that the presence or absence of a thin roof should not be the key defining factor. Third, we propose that active diapirism should be reserved for two specific scenarios: (1) uplift and folding of a thick roof during diapir rejuvenation and (2) the single brief stage when salt in a precursor structure (e.g., reactive diapir, salt-cored contractional fold, or salt pillow) breaks through its roof to subsequently rise as a passive diapir.

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.

From the 1970s, the Dead Sea experienced severe halo-karstification and anthropogenic modifications. Progressively, but at an accelerating rate, subsidence, landslides, and sinkholes have increased in number and magnitude. The hazards’ triggering factors are the terminal lake level lowering at more than one meter per year and the dynamic equilibrium of the hydrogeological system. Over the Lisan peninsula, archived satellite images revealed the extent of the damaged areas. On 22 March 2000, the destruction of dike 19 represented a loss of 38 M USD. This is the most important event recorded since the beginning of the Dead Sea recession some 50 years ago. In 2018, a rehabilitation project of that dike started. This research analyses the viability of the reinstatement works. The advanced space borne radar interferometry technique is applied to map ground deformations before and during the project. This article reveals that the ongoing rehabilitation and reinstatement works of dike 19 are threatened by ongoing halo-karstification processes. Field observations and subsidence/uplift dynamics support this statement. The past experiences are taken into consideration to adapt industrial expansion strategies. However, the permeability of the salt pan floor could trigger a fast development of a karst system able to destroy the rehabilitated dike 19.

From the analysis of the topography and geology of coronae on Venus, the most common topographic profiles of coronae were obtained, their relative age was estimated by the characteristic annulus type and the relation with the surrounding volcano−tectonic units, and the corona evolution stages consistent with numerical modeling results for the evolution of mantle diapirs on Venus were determined. It has been found that most coronae is the manifestation of a late regressive stage of the evolution of mantle diapirs. These coronae are spatially associated with groove belts and characterize late episodes of the tectonic resurfacing regime. According to our results, the number of coronae that may appear at the early and late phases of the regressive stage is almost the same. This allows us to suppose that the parent corona-forming diapirs were mostly formed at the end of the tectonic regime, but this activity had terminated before extensive lava plains (shield and regional plains) were formed during the volcanic regime. A minor portion of the entire corona population (18%) represents the initial, progressive, stage in the evolution of diapirs, which is characterized by growing a dome-shaped structure above a diapir.

Comparative analysis of three randomly chosen salt structures (diapir A, diapir B and diapir C) of the Southern North Sea has been presented through the interpretation and reconstruction of the 2D seismic data set (SNSTI-NL-87 & SNST-NL-83). The study area lies in the Southern North Sea, Dutch offshore and it was tectonically active in the Permian or prior to that, as the basement was faulted at several locations before the deposition of salt in the Late Permian. The salt started to move in the Late Triassic to the Early Jurassic and the resulting salt structures developed until the Mid-Miocene. In most of the cases salt started to move due to the basement faults but buoyancy and differential loading are also main factors for the initiation of the salt movement. Two main time periods are believed to enhance the salt movement in the study area i.e. the Late Jurassic to the Early Cretaceous (extension), and the Late Cretaceous to the Early Tertiary (inversion). The results show thick Triassic and Jurassic sediments in the graben area. In contrast, due to the possible erosion, thin layers of sediments observed on the structural highs. The Late Cretaceous was reported as the compressional period resulting thickness variations of sediments in the area.

Classic models of gravity-driven salt tectonics commonly depict kinematically-linked zones of overburden deformation, characterised by updip extension and downdip contraction, separated by a weakly deformed zone associated with downdip translation above a relatively smooth base-salt surface. We use 2D and 3D seismic reflection and borehole data from the south-central Campos Basin to show that these models fail to adequately capture the complex range of structural styles forming during salt-detached gravity-driven deformation above a rugose base-salt surface. In the Campos Basin the base-salt is defined by broadly NE-trending, margin-parallel, generally seaward-dipping ramps that have up to 2 km of structural relief. We define three domains of overburden deformation: an updip extensional domain, an intermediate multiphase domain, and a downdip contractional domain. The multiphase domain is defined by large, partly fault-bounded, ramp-syncline basins, the stratigraphic record of which suggest c. 28 km of seaward gravity-driven translation of salt and its overburden since the end of the Albian. We also identify three main types of salt structures in the multiphase domain: (i) contractional anticlines that were subjected to later extension and normal faulting; (ii) passive-to-active diapirs that were later extended and widened, and which are bound on their landward margins by landward-dipping, salt-detached normal faults; and (iii) reactive (extensional) diapirs that were subsequently squeezed. We argue that this multiphase deformation occurs because of basinward translation of salt and its overburden over complex base-salt relief, consistent with the predictions of physical models and several other seismic reflection data-based studies. Critically, these complex local strains overprint margin-scale patterns of deformation.

The Jebel El Akhouat Zn-Pb-(Ba-Sr) ore deposit, located in the Tunisian Dome zone, is hosted mainly in the organic matter-rich Albian and Cenomanian–Turonian rocks. The orebodies occur mainly as open-space fillings and are structurally-controlled. The paragenetic sequence consists of three stages, which reflect three ore events. Three discrete stages of Zn-Pb sulfide and/or Zn-Pb-Ba-Sr sulfide-sulfate ores are identified. Fluid inclusion study carried out on selected minerals of different stages reveals that sphalerite, galena, marcasite, celestine, barite, and fluorite precipitated as a result of mixing between a hydrothermal, saline, metal-rich basinal fluid and a low-temperature, less saline, metal-depleted, sulfur- or sulfate-rich fluid with the intermittent involvement of hydrocarbons. Based on sulfur isotope data, sulfur of sulfides was derived from the reduction of the dissolved Triassic sulfates primary through thermochemical sulfate reduction with a contribution of bacterial sulfate reduction. The Pb isotopic composition of galena samples and trace elements data of the host carbonate rocks suggest that metals were derived primarily from the Paleozoic siliciclastic rocks with a contribution of the organic matter-rich Albian and Cenomanian–Turonian rocks. The Alpine orogeny triggered the migration of the metalliferous fluids from the deep parts of the basin towards the peridiapiric paleohigh of Ech Chehid diapir through major faults towards the loci of deposition.

[Abstract Subsidence analysis study for several Triassic carbonate platforms from the eastern Northern Calcareous Alps shows that salt expulsion allowed for the growth of thick isolated depocentres (>1.5 km) at rates faster than those tectonic subsidence alone can provide. Our results, in addition to independent regional geological evidence, argue against previous models of thick‐skinned extension controlling accommodation space. Differential sedimentary loading and stretching of the salt layer can explain the development of the Triassic isolated carbonate platforms in the Northern Calcareous Alps, with salt expulsion being proportional to the growth potential of the carbonate producers. Aside of topographic loads, early diageneses of carbonates allow for the density inversion between sediment and salt, with differential loading by carbonate aggradation leading to a self‐sustained feedback cycle of density‐driven and gradient load subsidence; stretching of the salt layer and extensional deformation of its overburden, as constrained by cross‐section restoration, also contributed to diapir initiation and salt expulsion. Our model can: (a) explain the occurrence of isolated Middle Triassic carbonate platforms in the eastern Northern Calcareous Alps, and (b) differentiate between accommodation space controlled by (local) salt expulsion and by (regional) tectonic subsidence. The Triassic Neo‐Tethys shelf of the studied area constituted therefore a salt wall and minibasin province. This contribution and methods herein can also be applied to other carbonate platform systems developed on salt basins, especially where the transition from rift to drift remains unclear., Subsidence and growth rates of the Triassic units compared to subsidence mechanisms based on Schlager (1981). The accumulation rate of stratigraphic units is displayed in comparison to the derived total subsidence curve. Two kinds of units can be individuated based on their total subsidence curves: one group for which accommodation space was driven by thermal subsidence, and a second group falling above the thermal subsidence curve, indicating subsidence rates requiring salt expulsion in addition to cooling. ]

Extensive soft-sediment deformation (SSD) of multiple expressions and scales record active and dynamic events and processes in erg deposits of the Lower Jurassic Navajo Sandstone near Moab, Utah. The erg deposits preserve depositional environments of eolian dune, interdune, fluvial, playa, lake, and spring. A large range of SSD features, from intact beds showing little deformation to pervasively disturbed beds, exist in many of these deposits. A simplified classification index captures the different scales of SSD in ascending order of deformation intensity: 1) mostly intact bedding with small-scale wavy or undulatory deformation structures within single beds; 2) dish and flame structures; 3) meter-scale, kinked, slumped, rolled, overturned, vertical, and detached contorted crossbedding, and associated centimeter- to meter-scale pipes; and 4) disruptive diapirs and laterally extensive massive sandstone. The SSD features of deformed crossbed sets, diapirs, and massive sandstone beds, are consistently juxtaposed, and are thus genetically linked.Although the Navajo Sandstone has been considered a classic example of an extensive dry eolian system, both individual and combinations of strata bounded SSD features exemplify dynamic deformation, liquefaction, and fluidization that took place at various times after deposition. The lowest degree of deformation, SSD 1, is largely attributed to autogenic––inherent to the eolian system––or local allogenic processes. Larger degrees of deformation, SSD 2–4, were more likely produced by allogenic, external-forcing processes from regional changes in climate and/or near-surface groundwater conditions originating from the Uncompahgre uplift, with the deformation triggered by some event(s). Possible significant ground motion could have led to large-scale disruption in the Navajo sand sea across kilometer-scale intervals. The Navajo example establishes valuable hierarchical relationships of processes and products for recognizing and interpreting SSD in other ancient and modern eolian systems. This has particular relevance to sedimentary discoveries on Mars, where SSD features are visible from remote sensing imagery and rover exploration.

Analyzing the dynamics of microstructural response on natural deformation in rock salt, we present microfabric, EBSD, geochemical and U–Pb data, obtained from Permian salt formations of the Kiel-Honigsee salt wall in Northern Germany. The samples were recovered from deep drillings, which penetrated through an overturned rock salt sequence of both Rotliegend and Zechstein deposits. The bromide concentration in halite indicates a continental and marine origin for the Rotliegend and Zechstein deposits, respectively. Despite intense deformation, relics of early diagenetic fabrics are still preserved. Deformation of the impure Rotliegend rock salt was accommodated by pressure solution and hydrofracturing as is indicated by the microfabrics and bromide concentration in halite. Fractures in siliciclastic domains were filled with fibrous halite and deformed by subgrain rotation recrystallization (SGR). Fluid-rich Zechstein rock salt, on the other hand, was deformed by formation of subgrains and grain boundary migration (GBM). The distribution of mineral phases and fluids had a significant impact on the fabric evolution and on strain localization. U–Pb dating of carbonate phases of the Rotliegend sequence yielded Permian depositional ages and Jurassic to Cretaceous deformation ages, the latter related to diapiric ascent. The combination of results traces a dynamic evolution of the rock fabric inside the diapir structure driven by locally active deformation processes that can be correlated with early stages of halite deposition and diagenesis and syntectonic fabric reorganization related to diapirism in an extensional setting., Bundesministerium für Wirtschaft und Energie http://dx.doi.org/10.13039/501100006360

This study aims to demonstrate the morphotectonic evidence (drainage pattern, formations of sedimentary rocks, structural ridge deformations and spectral reflectance differences…etc.) for tectonic uplift with the syncline zone between two major anticlines, Kirkuk anticline in the northeast and Qara Chauq anticline in the southwest. The study area is located in the low folded zone at the geographical coordinates of 35º 45´ to 35º 55´ North and 43º 30´ to 44º 00´ East. In this study, the tectonic uplift was named as Dushwan uplift, because the uplift of the rocks was adjacent to Dushwan village. The regional stress, originating from the collision of the Arabian plate with the Eurasian plate, is still affecting the study area, as presented by the rock deformations of the southwestern structural ridges of Kirkuk anticline and the whole Qara Chauq structure. It is dividing the drainage pattern basin within the major syncline into two different drainage basins with different directions from the center of this uplift, in addition to the rocks deformation of the eastern plunge of Bai Hassan anticline. This uplift was demonstrated through four sectional profiles made by using Google Earth and Global Mapper software. In addition, the uplift of the rocks was identified by the visual interpretation of the satellite images and the digital interpretation of the DEM and satellite images using software (such as Arc GIS and Global Mapper) for the study area. The above morphotectonic evidence indicate that the rocks in the study area are influenced by tectonic activity (Dushwan uplift) through three suggested mechanisms; First, propagation of two synclines, one existed between Kirkuk anticline and Bai Hassan Anticline and the other located between Qara Chauq anticline and Guwair anticline of a northwest- southeast trend. Second, this uplift of the rocks was resulted by a deep-seated fault that extends to the basement faults with a northeast- southwest direction. Third, a Salt Diapir was forced from salty formations existed in this area.

Cadomian calc-alkaline I-type and within-plate A-type igneous rocks are widespread in the crust of Iran where they are ascribed to a convergent margin associated with the southward subduction of Prototethyan oceanic lithosphere beneath N Gondwana. These rocks are found as unmetamorphosed magmatic rocks and their metamorphic equivalents (mafic to felsic gneisses) could have been generated in both Cadomian arcs and associated rear-arcs. Nearly all these exposures also contain metamorphosed metasediments, whereas Cadomian igneous rocks of central Iran are associated with thick sequences of unmetamorphosed terrigenous rocks. In the Zagros Fold-Thrust belt of S Iran, salt diapirs contain abundant xenoliths of Cadomian igneous and sedimentary rocks in association with evaporites, dolomites, carbonates, and banded iron-salt deposits. This paper presents new zircon U-Pb and geochemical-isotopic data from igneous clasts in the Chah-Banu salt diapir in SE Zagros. Petrographic and geochemical data indicate two different types of rock clasts; calc-alkaline, I-type dacites-rhyolites, and arc-related to E-MORB-OIB-like gabbros, basalts, and dolerites. New zircon U-Pb ages show that dacites formed at 538.2 ± 2.2 Ma, whereas gabbros show ages of 539.0 ± 1.8 Ma. Zircons from dacites have negative εHf(t) values of – 1.1 to – 8.3. In contrast, zircons from gabbros have higher εHf(t) values of +4.5 to +8.5, indicating crystallization from mantle-derived juvenile magmas. Bulk rock Nd-Sr isotopic data (e.g. ɛNd(t) = +0.3 to +4.0 and 87Sr/86Sr(i) = 0.7059 to 0.70848) for gabbros, dolerites, and basalts confirm that these rocks originated from a mantle source similar to enriched parts of the subcontinental lithospheric mantle, whereas dacites and rhyolites (with εNd(t) = −3.4 to −4.1 and 87Sr/86Sr(i) = 0.70806 to 0.70907) show strong interaction with, and/or re-melting of older continental crust. We suggest that the bimodal calc-alkaline and E-MORB-OIB-like magmatic rocks in salt diapirs as well as associated evaporites and sedimentary rocks formed in a retro-arc rifted basin behind the Cadomian magmatic arc. published

Central Tunisia is characterized by major fault systems, being ornamented by salt diapirs of the Late Triassic evaporite-rich interval. Salt movement began in the Late Triassic and continues to the present-day. Lasting halokinesis create pillows, diapirs, salt wall and salt-cored folds, sometimes, with collapse graben above. Salt diapir structures have been mapped and many regions collapsed diapirs are, perhaps, associated to salt removal. These structures were eroded resulting exposure and sub-aerial erosion by the Late Cretaceous to Paleogene uplift and post-Middle Miocene. The initial studies and findings related to salt structures in Tunisia suggesting a clear correlation between diapiric uplift and local tectonic structures. In particular, the N‒S and NW‒SE shortening trends during the Neogene and Quaternary folding strongly controlled the development of rows of diapirs and salt walls. The salt activities are controlled by tectonics as well as differential loading in the Triassic sediments over long distances, displaying that the mobilization of Triassic sediments covered the whole region and not just the zones near the single diapiric structures. Here we will focus also in the salt related plays and the associated petroleum systems with particular emphasis on trap types, reservoir and hydrocarbon migration pathways. Obviously, all these elements are linked together to certain degree and controlled by the salt tectonics.

An integrated approach to Seismic interpretation that combines techniques of sequence stratigraphic analysis, seismic facies analysis and attribute analysis is one of the most effective approaches for hydrocarbon exploration in growth-faulted deltaic strata of offshore eastern Niger Delta. These strata are generally thick paralic/marine units deposited along an unstable progradational continental margin. Here, shale ridges, toe thrusts and diapirism are common features. Thus, system tracts along this margin differ significantly from those described for classic stable progradational continental margins. Development of good reservoir sands, on the shales of the upper transgressive systems tract form barriers which are good, particularly on the outer shelf where high stand systems tract sediments accumulate. Alternation of the high stand systems tract sands and transgressive systems tract shales provides a bridge linking reservoir facies with the shales or seals of TST which is essential for hydrocarbon accumulation and its stratigraphic trapping in the study field. This work has provided an analytical model for a detailed and cost-effective hydrocarbon prospecting through the use of sequence stratigraphic framework in tandem with seismic data interpretation. Key words: Sequence stratigraphy, seismic facies, system tracts, offshore Eastern Niger Delta.

The Huizhou Movement refers to the Middle Eocene tectonic transition from the early to the late Wenchang Rifting stage (about 43 Ma ago) in the Pearl River Mouth Basin. Based on seismic reflection, drilling, logging and geological data, fault characteristic analysis, denudation thickness recovery, magmatism statistics, regional tectonic dynamics comparison and other methods are used to reveal the characteristics, properties and dynamic mechanism of the Huizhou Movement. The Huizhou Movement mainly shows the North-South transition of rifting and the migration along the faults, basement uplift, magmatic diapir and stratigraphic denudation. It is believed that the Huizhou Movement is a comprehensive reflection of plate interaction and lithospheric thinning process in the Pearl River Mouth Basin, which is closely related to the transition of lithosphere from initial rifting to rapid thinning, the India-Eurasia hard collision and the change of subduction direction of the Pacific plate. The Huizhou Movement has significant influence and control on the Paleogene hydrocarbon-generating sags and the development of hydrocarbon source rocks, sedimentary system and deep high-quality reservoir, hydrocarbon migration and accumulation in the Pearl River Mouth Basin.

The Zagros Belt has examples of strike-slip faults affected by precursor Hormuz Salt bodies. We attempted to examine the role of salt walls in localizing the strike-slip faults using field observations, seismic profiles and understandings from the sandbox modeling. Setting and performance of the pre-Hormuz features in connection to the salt tectonics are major questions. The inherited topography below the salt is an important parameter which controlled the structuration of the basin. The antecedent troughs provided accommodation for the thick Hormuz Salt. Differential loading above the salt helped generation of salt-related structures. The salt-walls caused formation of elongated highs. These highs were re-shaped in form of strike-slip faults during the Zagros Orogeny. The intersection of the salt walls and the Zagros-induced deformation fronts are location of potential diapirs needless of bending points along the tear faults. In contrast, the underlying deep-seated basement faults are hardly believed to be strike-slip.

Geological studies show that the southern part of Ailaoshan-Red River shear zone (ALSRRSZ) has experienced complex metallogenic processes and multi-stage non-uniform uplifting, called oblique uplifting since the Cenozoic. To detect the deep structure and geodynamic background beneath Daping, Chang’an and other gold and polymetallic deposits in this area, we carried out a high-density short-period seismic array survey in southern Yunnan province. The array used is approximately 240 km long with an interval of 500 m between two adjacent stations. Based on the data collected by the array, we used H-κ stacking and common conversion point (CCP) methods of receiver functions to reveal the fine crustal structure beneath this array, which was located from Lvchun (western end) to the east and ended in Maguan. The three main conclusions are as follows. (1) The average crustal thickness is approximately 37 km and the Vp/Vs ratio is 1.75. However, the thickness and Vp/Vs ratio of the Ailao Mountain are rather greater or higher than those of the western Lanping-Simao Basin and eastern South-China block. These results may indicate that the crust is rich in ferromagnesian minerals or has a thermal fluid anomaly after orogenic movement. (2) There are two obvious inclined interfaces beneath the Ailao Mountain in the mid-upper crust, which suggests that strong deformation occurred there during the orogenic period. Some evidences, such as the weak converted-wave Pms phase from the Moho, low P-wave velocities of the upper mantle, high surface heat flow values, and generally developed hot springs, indicate that a strong crust-mantle interaction exists in the southern segments of the Ailaoshan-Red River shear zone. These interactions include a diapir of mantle-sourced magma (stronger in the east than that in the west), lateral collision from the Indian Plate, and the differential uplift caused by the strike-slip movement of the Red River Fault. All of above deep processes led to the Cenozoic oblique uplifting of Ailao Mountain. (3) By combining the location of the deposits on the surface, characteristics of the average crustal Vp/Vs ratio, hypocenters of the small earthquakes along the research profile, Moho shape, and horizontal variations of the Pms phase amplitudes, we speculate that the Ailaoshan Fault was the upgoing conduit for metallogenic magma and played a significant role in the Cenozoic development of the multiform metal deposits around the Ailao Mountain area.

Salt tectonics in the Eastern Persian Gulf (Iran) is linked to a unique salt‐bearing system involving two overlapping ‘autochthonous’ mobile source layers, the Ediacaran–Early Cambrian Hormuz Salt and the Late Oligocene–Early Miocene Fars Salt. Interpretations of reflection seismic profiles and sequential cross‐section restorations are presented to decipher the evolution of salt structures from the two source layers and their kinematic interaction on the style of salt flow. Seismic interpretations illustrate that the Hormuz and Fars salts started flowing in the Early Palaeozoic (likely Cambrian) and Early Miocene, respectively, shortly after their deposition. Differential sedimentary loading (downbuilding) and subsalt basement faults initiated and localized the flow of the Hormuz Salt and the related salt structures. The resultant diapirs grew by passive diapirism until Late Cretaceous, whereas the pillows became inactive during the Mesozoic after a progressive decline of growth in the Late Palaeozoic. The diapirs and pillows were then subjected to a Palaeocene–Eocene contractional deformation event, which squeezed the diapirs. The consequence was significant salt extrusion, leading to the development of allochthonous salt sheets and wings. Subsequent rise of the Hormuz Salt occurred in wider salt stocks and secondary salt walls by coeval passive diapirism and tectonic shortening since Late Oligocene. Evacuation and diapirism of the Fars Salt was driven mainly by differential sedimentary loading in annular and elongate minibasins overlying the salt and locally by downslope gliding around pre‐existing stocks of the Hormuz Salt. At earlier stages, the Fars Salt flowed not only towards the pre‐existing Hormuz stocks but also away from them to initiate ring‐like salt walls and anticlines around some of the stocks. Subsequently, once primary welds developed around these stocks, the Fars Salt flowed outwards to source the peripheral salt walls. Our results reveal that evolving pre‐existing salt structures from an older source layer have triggered the flow of a younger salt layer and controlled the resulting salt structures. This interaction complicates the flow direction of the younger salt layer, the geometry and spatial distribution of its structures, as well as minibasin depocentre migration through time. Even though dealing with a unique case of two ‘autochthonous’ mobile salt layers, this work may also provide constraints on our understanding of the kinematics of salt flow and diapirism in other salt basins having significant ‘allochthonous’ salt that is coevally affected by deformation of the deeper autochthonous salt layer and related structures.

Petrogeochemical and geochronological studies were conducted on the main varieties of granitoids from the Sedelga and Berezovsky batholiths in the eastern Bureya continental Massif of the Central Asian Fold Belt. SHRIMP-II U–Pb zircon dating of granitoids constrained the time of formation to the Late Triassic and Early Jurassic between 208 to 193 Ma. Our studies revealed that the batholiths contain peraluminous granitoids of high K calc-alkaline series clearly enriched in Rb, K, Th, U, and Pb and relatively depleted in Nb, Ta, Y, HREE, Sr, Ba, Ti, and P and belong to I-type granites. Synthesis of the U–Pb geochronological data indicates that magmatism of tectonic blocks constituting the Bureya Massif at 213–183 Ma was accompanied by the emplacement of granitoid rocks of the Khara Complex. Strike-slip tectonics as a reflection of oblique collision of continental blocks and transform movement might have been an important mechanism of granitoid derivation in the Bureya Massif. Strike-slip faults were likely to penetrate deep into the crust initiating the ascent of an asthenospheric diapir and its fluids into the higher crustal levels thus transferring the heat and triggering melting with appreciable concentrations of Th, U, Rb, Pb and losses of Sr, P, Ba, and Ti. The depletion in Nb, Ta, Ti, and P and the enrichment in Pb make these granitoids similar to those of subduction zones. Granitoids of the Khara Complex display subduction-related (associated with the preceding subduction) and within-plate (associated with an asthenospheric diapir and its fluids) geochemical features, which is characteristic of transform margin environments. The most likely settings for granitoid magmatism to occur throughout the eastern margin of the Bureya Massif in the Late Triassic and Early Jurassic were transform settings associated with asthenospheric diapirism following the cessation of subduction.

Ceres is the largest body in the Main Belt, and it is characterized by a large abundance of water ice in its interior. This feature is suggested by its relatively low bulk density (2162 kg m−3), while its partial differentiation into a rocky core and icy crust is suggested by several geological and geochemical features: minerals and salts produced by aqueous alteration, icy patches on the surface, and lobate morphology interpreted as surface flows. In this work, we explore how the composition can influence the characteristics of thermal convection in the crust of Ceres. Our results suggest that the onset of thermal convection is difficult and when it occurs, it is short lived, which could imply that Ceres preserved deep liquid until present, as recently suggested by the work of Castillo-Rogez et al. Moreover, cryovolcanism could be driven by diapirism (chemical convection) rather than thermal convection.

The gas charging influences on dissolution, cementation, and clay transformation are still largely unknown during the migration and accumulation of hydrocarbons. The reservoirs in the upper Huangliu Formation of the XF13 block in the Yinggehai Basin, South China Sea, were charged by CO2 and gaseous hydrocarbons, offering us an ideal opportunity to quantitatively study the diagenetic differences caused by gas charging with different compositions. The techniques and methods used in this study include optical microscopy, scanning electron microscopy, cathodoluminescence, x-ray diffraction, chemical analysis of formation water, stable isotope analyses, and fluid inclusion examination. These analyses demonstrate that the late-stage charging of CO2-rich thermal fluid in the wells near the diapir zone modified porosity, permeability, temperature, fluid pH, and contents of K+, Na+, Mg2+, Fe2+, and other ions. Natural gas accumulations with high maturity and high CO2 contents presented at wells XF13A and XF13B near the diapir zone resulted from episodic mixing and modification. Wells far from the diapir zone (e.g., XF13E and XF13F) mostly show alkane enrichment. Late-stage charging of CO2-rich thermal fluids at wells XF13A and XF13B (in a closed system with episodic semiopen events) has resulted in significant dissolution and caused reservoirs with high porosity but low permeability. In contrast, wells far from the diapir zone were only charged by early-stage hydrocarbons, and the porosity and permeability are relatively high. This study is important in predicting reservoir quality according to gas compositions of reservoirs.

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