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The Dongpu Sag exhibits highly representative structural features of the Bohai Bay Basin. By utilizing time depth quantification (TDQ) technology, geological profiles were generated through the processing of seismic data with a velocity model. These profiles were integrated to investigate the linkage geometry and timing of the Lanliao fault, the eastern boundary fault of the Dongpu Sag. Structural analysis revealed at least five original fault segments of the Lanliao fault, each initiating independently during the early growth phase. The development of these isolated fault segments began in the early Eocene, which is concurrent with the deposition of the Es4 member. The southern fault segments were active earlier but became inactive later as the northern segments gained activity during the Es3 member. Transverse anticlines separate the northern and southern faults. By the time of the Es2 member, all segments had linked, forming a continuous boundary fault across the transverse anticlines. As the Dongpu Sag expanded, the depocenter relocated. The southern fault formed a graben, known as the Gegangji subsag, controlling the depocenter during the Es33 and Es32 members. The depocenter of the Es31 member shifted northward swiftly, developing into a half-graben depocenter called the Huzhuangji subsag. In the post-linkage development phase, the activity of the Lanliao fault decreased over time, with displacement becoming more concentrated on the Huanghe fault, an intrabasin fault. The Huanghe fault then dominated basin sedimentation, moving the depocenter to the Mengmangji subsag. This study demonstrates that the fault linkage is a significant event in basin evolution, exerting considerable control over sedimentation and the overall evolution of the basin. [ABSTRACT FROM AUTHOR]

A sedimentary basin is a depression where sediment deposits accumulate and can act as a reservoir for the sedimentation and maturation of sediments containing hydrocarbons. The Bengkulu Basin is one of the forearcs in Indonesia. The Bengkulu Basin is one of the basins with the potential to have hydrocarbon reserves marked by an oil show in the Padang Capo village. Exploration to find a basin or hydrocarbon trap can be done using the gravity method. This method is often used to study the structure, bedrock, rock intrusion, and sedimentary basins based on variations in the earth's gravitational field due to lateral density differences which are known as anomalies gravitational. Determination of the existence of a hydrocarbon trap structure is carried out by derivative analysis, namely First Horizontal Derivative (FHD) and Second Vertical derivative (SVD) graphs and 2D modeling using forward modeling. The results of the analysis of the FHD and SVD graphs with 2D modeling show synchronous results. Where the analysis of the FHD and SVD graphs in the study area found many fault structures and folds. The study area is dominated by the fault type of thrust fault. In the 2-dimensional modeling of the research area where there is an oil show, it is found that there is a rising fault structure and the presence of anticline and syncline structures that could act as hydrocarbon traps. [ABSTRACT FROM AUTHOR]

Regional magnetic data in the southeastern segment of the Nigerian Niger Delta were evaluated with the aim of mapping deep-seated tectonic elements. Enhanced filtering operations and 3D forward modelling were applied on the magnetic data. These geologic features triggered the formation of rollover anticlines and faults that serve as structural traps in the study area. The filtered residual magnetic data revealed geologic structures characterized with NE -- SW, N -- S, and E -- W orientations. The 3-D models detected the faulted crustal blocks, gradient zones, and intra-basement compositional magnetic variations. Furthermore, some prominent horst and graben structures as well as related normal faults characterized with distinct magnetic signatures were observed. Faults of base magnetic (of various compositions) were observed to be the fabricating mechanisms of the magnetic anomalies. Collectively, these structures influenced the patterns of magnetic anomalies with direct effects on the hydrocarbon trapping systems, as well as the pathways and accumulation zones for hydrothermal minerals. On the whole, the interpreted results revealed that the basement surface is rippling. Additionally, the depth result showed sedimentary thicknesses that ranged from 4-10 km. Again, the estimated crustal thickness varied from 14 to 19 km. This study has displayed the capabilities of the magnetic method in mapping the depth and configuration of basement rocks, which are crucial in controlling the formation of structural traps. Identifying these basement structures early helps in understanding the overall geological framework and potential hydrocarbon systems. [ABSTRACT FROM AUTHOR]

The impacts of the growth and linkage of fault segments on sedimentation in a lacustrine rift basin, the Weixinan Depression, the Beibuwan Basin, in the northern South China Sea, which has been demonstrated to have huge petroleum potential, are elucidated on the basis of well-constrained 3D seismic data. Two main fault systems, the No. 1 boundary fault system and the No. 2 fault system, were developed in the Weixinan Depression. The evolution of the lower basement is based on the No. 1 fault system, which controls the distribution of depocenters (ranging from 450–800 m) within the lower structural layer. It includes the five fault segments isolated at the initial stage, the interaction and propagation stage, the linkage stage, and the decline stage. The No. 2 fault system governs the deposition of the upper structural layer with a series of discrete depocenters in the hangingwall. Initially, it comprises several right-order echelon branching faults. Each branch fault rapidly reached the existing length and maintained a constant length while establishing soft links with each other in the subsequent displacement accrual. The development of topographic slopes, transition zones, transverse anticlines, and related fault troughs and gullies related to the activity of the No. 1 boundary fault system is the main controlling factor that induces the differential development of the western, middle, and eastern sections of steep slope fans. The differential subsidence effect along the No. 2 fault system is responsible for the multiple 'rising-stable' stage changes in the relative lake level during the development of axial delta deposits. This study will help elucidate the different controls of extensional fault systems on associated sedimentation, as well as rift basin development in the South China Sea and similar areas throughout the world. [ABSTRACT FROM AUTHOR]

How subsurface anticlines (oil fields) link structurally with faults is of great relevance in the exploration and development of oil fields. In this context, we investigate the geometric relation between lower Balarud (LBR), upper Balarud (UBR) and Qaleh Nar (QN) subsurface anticlines that are the main oil fields in the Northern Dezful Embayment, central Zagros. The Asmari (As) and the Bangestan (Bng) reservoirs are studied geophysically using seismic profiles, well data and underground contour maps (UGC). Interpretation of 3500 m deep seismic profiles indicates the geometry of the studied subsurface anticlines differs vertically and horizontally to a significant proportion. The interpreted structures much resemble As and Bng horizons in each anticline. The UBR got overturned on the LBR due to thrusting possibly in the Late Miocene. The LBR, like a rabbit-ear structure, is situated at the northern edge of the QN. The lower and upper Chenareh and LBR and UBR resemble structurally and are separated mutually by a steep (strike-slip) fault. The fault separates the LBR and UBR from the QN. Interaction of different factors change in overburden pressure, rate of deformation and uplift in the different parts of the subsurface anticlines moved and accumulated Gachsaran Formation towards both limbs of the anticlines. [ABSTRACT FROM AUTHOR]

The Xihu Depression is the largest hydrocarbon-bearing depression of the East China Sea Shelf Basin (also referred to as the ECSSB). However, the depositional systems and reservoir distribution of the Oligocene Huagang Formation in the Xihu Depression are still controversial. Under the guidance of sedimentology and stratigraphy, this study documented a marine-terrestrial transitional environment in the restricted bay setting of the Oligocene Huagang Formation through core description, well logging, and seismic data analysis. This study also revealed that the Oligocene Huagang Formation is dominated by tidal delta, estuary, and gravity flow deposits in the central anticline zone of the Xihu Depression. The new understanding of the sedimentary systems and the discovery of the transgressive gap in the eastern Diaoyu Islands uplift explain the origin of fine-grained sediments and the EW-trending sand bodies in the central depression and the sand bodies parallel to shoreline in the west slope belt, which cannot be explained by previous study results, such as southern transgression or fluvial deltas and even lacustrine deposition. Moreover, the tidal channels, tidal sand flats, and gravity flow sand bodies formed by the transgressive tides are high-quality reservoirs. The study will provide a basis for well placement and serve as guidance for the selection of favorable hydrocarbon exploration areas in the Xihu Depression. [ABSTRACT FROM AUTHOR]

Copyright of Iraqi National Journal of Earth Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The question of uplift in the Sarawak Foreland is addressed in a multi-disciplinary approach, namely by assigning surface vitrinite reflectance measurements to depth, and by vitrinite reflectance-to-depth conversion using functions from two previous studies. Additional erosion and uplift data were obtained by comparing eroded anticlinal crests with adjacent synclines and their preserved sediments. The combined data pool suggests two types of uplift (I) a regional uplift in the Neogene affecting the entire coastal area, and (II) a tectonically focused uplift. The amount of the latter uplift and erosion is directly linked to rise of anticlinal structures during the Upper Pliocene, with a total uplift ranging from 700 to 4,000 m in areas along prominent regional faults. Within a very short time window major sedimentation, folding, trap formation and trap destruction took place both as a consequence of folding and erosion. Only anticlines in the offshore and the proximal onshore appear to have survived without major crestal erosion. Since the end of the Pleistocene, a rise of foreland sections by some 132 m is recognized. The rapid Pliocene burial and the erosion that consequently removed the overburden thereafter may have negatively affected the petroleum system and hydrocarbon accumulation within the Miri area, which was left largely intact only in the Siwa-Seria anticlinal trend. All anticlines were targeted by petroleum exploration. However, only the Siwa-Seria trend has proved to be economically successful. This has highlighted the significance of overburden in relation to depth of burial and the thermal effect needed to mature the source rocks capable to generate hydrocarbons. [ABSTRACT FROM AUTHOR]

In microseismic monitoring, the reconstruction of a reliable velocity model is essential for precise seismic source localization and subsurface imaging. However, traditional methods for microseismic velocity inversion face challenges in terms of precision and computational efficiency. In this paper, we use deep learning (DL) algorithms to achieve precise and efficient real-time microseismic velocity modeling, which holds significant importance for ensuring engineering safety and preventing geological disasters in microseismic monitoring. Given that this task was approached as a non-linear regression problem, we adopted and modified the Attention U-Net network for inversion. Depending on the degree of coupling among microseismic events, we trained the network using both single-event and multi-event simulation records as feature datasets. This approach can achieve velocity modeling when dealing with inseparable microseismic records. Numerical tests demonstrate that the Attention U-Net can automatically uncover latent features and patterns between microseismic records and velocity models. It performs effectively in real time and achieves high precision in velocity modeling for Tilted Transverse Isotropy (TTI) velocity structures such as anticlines, synclines, and anomalous velocity models. Furthermore, it can provide reliable initial models for traditional methods. [ABSTRACT FROM AUTHOR]

Copyright of Advanced Applied Geology is the property of Shahid Chamran University of Ahvaz and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mud volcanoes are fed largely by fracture systems, but fracture systems are common in fold-and-thrust belts (FTBs), and not all of them extrude mud volcanoes. One popular hypothesis is that mud volcanoes extrude up normal faults and fractures in the crests of thrust-related anticlines. Using a high-resolution depth-migrated seismic cube in the northwestern Gulf of Mexico, we demonstrate the occurrence of buried mud volcanoes (shale sheets) that appear to have been fed by fluids moving up the thrust faults themselves. Mobile shales in this deepwater FTB detach a mostly welded allochthonous salt sheet. The main phase of shortening was during the Miocene, accompanying the sedimentation. Shortening generated multiple detachment levels, stacked duplexes, thrusts, and folds affecting the Oligocene mobile shales. Above these detachments, syn-sedimentary shortening initially generated detachment folds that progressively evolved into upward-propagating listric thrusts and fault-propagation anticlines. Shale sheets formed near the central thrust domains, associated with higher fault dips and larger fault displacements. We argue that their feeder systems were probably thrust-related shear zones that widened upward and comprised networks of anastomosing fractures. Finally, we propose that the position of mud volcanoes with respect to the underlying thrust systems depends on the path of least resistance to the surface. Although overpressured muds may vertically reach the surface via extensional fractures in the crests of thrust-related anticlines, we have shown to the contrary that when thrusts are emergent in a deepwater FTB, fluids continue up the inclined thrusts and adjacent fractures, forming mud volcanoes at the thrust tips. [ABSTRACT FROM AUTHOR]

The balancing technique, called 2D kinematic forward modelling, is a powerful tool to understand the kinematic evolution of fold-and-thrust belts. This study presents a new 2D kinematic forward model for the westernmost Internal Jura fold-and-thrust belt (FTB), situated immediately adjacent to the Geneva Basin. The technique used not only provides a new valid balanced cross-section but also offers new insights regarding the kinematic evolution of the Western Internal Jura FTB. Our model proposes a pure thin-skinned style dominated by forward stepping deformation accompanied by minor back-stepping thrust sequences. A first deformation step is attributed to the thrusting of the Crêt de la Neige Anticline, followed by the Crêt Chalam Thrust and its imbrications. This is followed by thrusting along the Tacon and the Bienne thrusts. Imbricate fault-bend folding explains the steep southern limb of the Crêt de la Neige and the Bellecombe anticlines. 2D kinematic forward modelling yields a total amount of shortening by 23.6 km for the Western Internal Jura FTB. In addition to the primary décollement located at the base of the Keuper Group evaporites, three other décollements are found within the marly layers of the Aalenian "faciès de transition" units, the Oxfordian "Couches d'Effingen-Geissberg" members and the Berriasian Goldberg formation. The multiple thrust horizon approach is supported by new precise seismic interpretations. Our model provides a valid alternative to previous models that either propose local thickening of the Triassic evaporites or inversion of normal faults in the basement. This fully explains the elevated position of the Mesozoic cover in the Jura FTB. [ABSTRACT FROM AUTHOR]

Reflector-normal angles and reflector-curvature parameters are the principal geometric attributes used in seismic interpretation for characterizing the orientations and shapes, respectively, of geological reflecting surfaces. Commonly, the input data set for their computation consists of fine 3-D grids of scalar fields representing either the seismic-driven reflectivities (e.g. amplitudes of 3-D seismic migrated volumes) or model-driven reflectivities, computed, for example, from the derived elastic impedance parameters. Conventionally, the computation of curvature parameters at each gridpoint is based on analysing the local change in the inline/crossline dips, considering the potential existence of a local quadratic reflecting surface in the vicinity of that point. This assumption breaks down for subsurface points in the vicinity of either complex reflecting surfaces (e.g. brittle/rough/tilted synclines/anticlines, ridges/troughs and saddles) and/or sharp, discontinuous geological features (e.g. fault edges/tips, pinch-outs, fracture systems, channels and small geobodies), where the values of the computed curvature become extremely high. However, while these high values can indicate the existence of non-reflecting objects, they do not deliver their specific geometric characteristics. In this study, we present a novel method that better characterizes the shapes of these complex geological features by extending the assumption of local surfaces (2-D surfaces in 3-D space) into local hypersurfaces (3-D hypersurfaces in 4-D space), with their corresponding (three rather than two) principal (and effective) curvature parameters. We demonstrate the advantages of our method by comparing the conventional dip-based surface curvature parameters with the hypersurface curvature parameters, using a synthetic model/image with different types and shapes of geological features and a seismic image of real data containing a complex fault and hidden buried channels. [ABSTRACT FROM AUTHOR]

This work uses sandbox analog models to analyze the formation and subsequent inversion of a decoupled extensional system comprised of two segmented half-grabens separated by a diffuse accommodation zone with thick early syn-rift salt. The segmented half-grabens strike perpendicular to the direction of extension and subsequent shortening. Rifting first created a basement topography that was infilled by model salt, followed by a second phase of extension and sedimentation, followed afterwards by inversion. During the second phase of extension, syn-rift syncline minibasins developed above the basement extensional system and extended beyond the confines of the fault blocks. Sedimentary downbuilding and extension initiated the migration of model salt to the basement highs, forming salt anticlines, reactive diapirs, and salt walls perpendicular to the direction of extension, except for along the intervening accommodation zone where a slightly oblique salt anticline developed. Inversion resulted in decoupled cover and basement thrust systems. Thrusts in the cover system nucleated along squeezed salt structures and along primary welds. New primary welds developed where the cover sequence touched down on basement thrust tips due to uplift, salt extrusion, and syn-contractional downbuilding caused by the loading of syn-contractional sedimentation. Model geometries reveal the control imposed by the basement configuration and distribution of salt in the development of a thrust front from the inversion of a salt-bearing extensional system. In 3D, the interaction of salt migrating from adjacent syn-rift basins can modify the expected salt structure geometry, which may in turn influence the location and style of thrust in the cover sequence upon inversion. Results are compared to the Northern Lusitanian Basin, offshore Portugal, and the Isábena area of the South-Central Pyrenees, Spain. [ABSTRACT FROM AUTHOR]

South West Abu-Sennan (SWS) area near the southern periphery of the Abu-Gharadig petroliferous basin in the Egyptian Northern Western Desert is an important hydrocarbon field characterized by being a multi-reservoir with a complex structural architecture. Therefore, in this study, we illustrated the regional structural role that facilitated having Jurassic mature source rocks (Masajid and Khatatba formations) through surgical seismic interpretation and observed the controlling petroleum system of the study area using a set of 20 seismic lines and 4 wells data. The study resulted in having the SWS oil field controlled by a strike-slip movement that occurred during the Upper Cretaceous time accompanying the African Plate movement against the Eurasian Plate superimposing an ENE–WSW strike-slip fault zone in the region and a strong pattern of NW–SEoriented faults due to numerous phases of extension. The associated structures include horsts, normal fault propagation folds, and strike-slip-related anticlines. The strike-slip tectonics played a major role in forming entrapment for the Jurassic expelled hydrocarbons. The seismic horizons flattening exercise performed on AR/G member and Khoman Formation demonstrated that the main reason for not having hydrocarbon accumulations in the Jurassic levels in the study area is that the trap configuration was ready to accumulate hydrocarbon but after the hydrocarbon generation and migration time. The study concluded that the hydrocarbons migrated along the faults which cut deeply to the source rocks and entrapped in the possible cretaceous reservoirs during the late cretaceous time. The conducted workflow in this study can be utilized to better explore and develop cretaceous reservoirs in the study and neighbouring areas. [ABSTRACT FROM AUTHOR]

Fluid inclusion microthermometry of synkinematic veins is used to estimate the maximum syntectonic load that was deposited on the wedge top in the central Appalachians (northeastern United States) during the Alleghanian orogeny. The restored loads indicate two major depocenters during the Alleghanian orogeny: one above Broadtop synclinorium, with as much as 7 km of Pennsylvanian– Permian load probably sourced by the erosion of rocks uplifted by the growing Blue Ridge massif and emplacement of the North Mountain thrust sheet; the other above the Anthracite belt, with as much as 16 km of syntectonic load likely sourced by the erosion of rocks uplifted by the growing Reading Prong massif. The loads were generally <3 km in the intervening Juniata culmination. In areas of high load, the structural architecture of the basin is that of widely spaced thrusts (~17–22 km) with large leading- edge anticlines in the Cambrian–Ordovician lithotectonic unit, while in areas of low load, thrusts are more closely spaced (~15 km) and deformed into an imbricate stack. The relationship between observed syntectonic loads, thrust spacing, and structural style reflect modeled relationships. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Geology & Recovery Efficiency is the property of Petroleum Geology & Recovery Efficiency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Affected by Tianshan uplift, the southern Junggar Basin has experienced multi-stage tectonic movements and formed many large-scale anticlines with zonal distribution. The key to hydrocarbon exploration is to accurately implement anticline traps. This paper is guided by the fault-related folds theory to tectonically interpret several seismic profiles in the southern Junggar Basin and then summarize the anticline types and their hydrocarbon accumulation characteristics. This paper showed that the southern Junggar Basin has a tectonic assemblage pattern of "multi-detachment layers and multi-phase superposition". According to the superimposed shape of the anticlines, they could be divided into overthrust anticlines, compound anticlines and multiple superimposed anticlines, and the horizontal and vertical positions of the different types of anticlines are different. The hydrocarbon accumulating characteristics of the different types of anticlines are shown to be different. The highs of the overthrust anticlines and compound anticlines are stable, and the degree of exploration is relatively high. Although the degree of exploration of multiple overlapping anticlines is low, multiple layers can be exploited simultaneously in the process of oil development, with great hydrocarbon potential. The characteristics of hydrocarbon accumulation in the southern Junggar Basin are discussed in order to provide guidance for efficient hydrocarbon exploration. [ABSTRACT FROM AUTHOR]

The Kurdistan Region of Iraq (KRI) forms the northeastern part of the Arabian Plate that is colliding with the Eurasian Plate. Due to the ongoing collision, the whole KRI territory is folded; accordingly, long anticlines are developed in NW - SE trend, they change west wards to almost E - W. The Cretaceous carbonate rocks form the bulk of the anticlines; in the central part of KRG. North and northwest wards, rocks of Paleozoic, Triassic and Jurassic ages are exposed in the core of some anticlines. Whereas southwards, Tertiary rocks are exposed in the core of anticlines. From tectonic point of view, the KRI territory is located in four tectonic zones; each has its own characteristics. Majority of the developed anticlines at the KRI are thrusted and exhibit lateral growth. We have presented many examples of laterally growing anticlines with clear indications for their growth. [ABSTRACT FROM AUTHOR]

The Zagros Fold and Thrust belt is one of the world's most prolific petroleum provinces. Most hydrocarbon reserves are stored in naturally fractured reservoirs and such fracture systems can therefore have a significant impact on reservoir performance. Fractures are one of the most important paths for fluid flow in carbonate reservoirs. Fracture data were collected in the outcrops of the Kirkuk Group of Oligocene age around Qara Chauq South and Qara Chauq North anticlines located near the Kirkuk Oil Field. The studied formations outcropping in the Qara Chauq are the main reservoir units in the Kirkuk and Bai Hassan fields. In Kirkuk and surrounding fields, hydrocarbon production comes mainly from primary porosity with assistance from secondary porosity created by dolomitization, karstification, dissolution, vugs and fractures. Fracture attributes collected from outcrops are fracture orientation, density and length. The results show that fractures in the studied reservoir formation are not uniformly distributed due to massive lithologic nature and lack of well bedding. Furthermore, fracture orientations show a clear relationship to the local fold axis in the outcrops. NW-SE fracture set is perpendicular to the NW-SE fold axis. However, some fractures do not show any relation to the local folding. These fractures may have formed in a pre-folding or post folding stage. Other fracture orientations exhibit a symmetrical relation to the maximum horizontal stress direction. The comparative analysis of outcrop data underlines the importance of representative analogue data for reservoir modelling and production strategies. [ABSTRACT FROM AUTHOR]

We describe two 5–7 km long normal fault scarps (NFSs) occurring atop fault-related anticlines in the coastal ranges of the Dinarides fold-and-thrust belt in southern Montenegro, a region under predominant contraction. Both NFSs show well-exposed, 6–9 m high, striated, and locally polished fault surfaces, cutting uniformly northeastward-dipping limestone beds at high angles and documenting active faulting. Sharply delimited ribbons on free rock faces show different colors, varying karstification, and lichen growth and suggest stepwise footwall exhumation, which is typical of repeated normal faulting during earthquake events. Displacements, surface rupture lengths, and geometries of the outcropping fault planes imply paleoearthquakes with Mw≈6 ± 0.5 and slip rates of ∼ 0.5–1.5 mm yr -1 since the Last Glacial Maximum. This is well in line with (more reliable, higher-resolution) slip rates based on cosmogenic 36 Cl data from the scarps for which modeling suggests 1.5 ± 0.1 mm yr -1 and 6–15 cm slip every 35–100 years during the last ∼ 6 kyr. The total throw on both NFSs – although poorly constrained – is estimated to ∼ 200 m and offsets the basal thrust of a regionally important tectonic unit. The NFSs are incipient extensional structures cutting (and postdating emplacement of) the uppermost Dinaric thrust stacks down to an unknown depth. To explain their existence in a region apparently under pure contraction, we consider two possibilities: (i) syn-convergent NFS development or – less likely – (ii) a hitherto undocumented propagation of extensional tectonics from the hinterland. Interestingly, the position of the extensional features documented here agrees with geodetic data, suggesting that our study area is located broadly at the transition from NE–SW-directed shortening in the northwest to NE–SW-directed extension to the southeast. While the contraction reflects ongoing Adria–Europe convergence taken up along the frontal portions of the Dinarides, the incipient extensional structures might be induced by rollback of the Hellenic slab in the southeast, whose effects on the upper plate appear to be migrating along-strike of the Hellenides towards the northwest. In that sense, the newly found NFSs possibly provide evidence for a kinematic change of a thrust belt segment over time. However, with a significantly higher probability, they can be regarded as second-order features accommodating geometrical changes in the underlying first-order thrust faults to which they are tied genetically. [ABSTRACT FROM AUTHOR]

Beachrocks are generally mapped on the coastline surface and/or in a low depth in the subtidal zone in coastlines and are cemented chiefly by carbonate material. Their outcrops may vary from a tenth of meters to a tenth of kilometers in length. Along the Epirus coast, in Greece, beachrocks outcrops are laying on the coastline for more than ten kilometers. In the present work, we used Unmanned Aerial Vehicles (UAVs), in situ sampling, and the Geographical Information System (GIS) to map three beachrock areas with a length of 500 m to 600 m each. In synergy with extended mineralogical and petrographic analyses, we provide preliminary data about the geographical distribution and the mineralogical differences of these beachrocks. Furthermore, for the first time, we tried to investigate the correlation between the geotectonic setting of the broader area and the beachrock extent, shape, and petrographic parameters. The laboratory analyses proved that the beachrocks belong to a similar depositional zone of a marine–vadose environment. Despite variations in the textural petrographic, features among the specimen's analyses permit us to consider these sedimentary rocks as not a uniform outcrop. It is indicated that the beachrock formation and the cementation progress in the study area are both controlled by active reverse faults and diapiric or tectonic anticlines. [ABSTRACT FROM AUTHOR]

Landslides are one of the natural hazards that many countries around the world are facing. In Morocco, the Rif regions are the most affected by these phenomena. Each year they cause enormous damage to the road network and infrastructure, especially in our study region, the province of Larache. The study region is subject to several opening up and road construction projects, which is why it is necessary to predict and identify the most vulnerable areas beforehand, in order to propose measures and techniques which are adequate for protection and reinforcement. The main goal of this study is to develop a susceptibility map to ground movements using a multi-criteria spatial assessment approach, and in order to reduce subjectivity, we have used a method for analyzing such complex decisions, which is the analytic hierarchy process (AHP) implemented in the geographic information system (GIS). Seven factors have been considered as conditioning factors in the occurrence of landslides, which are: lithology, fracturing density, slope, aspect, land use, density of the hydrographic network, and altitude. To verify the results obtained, we performed a correlation analysis of ground movements, already inventoried and verified in the field, with the susceptibility classes that were calculated. This analysis is accompanied by a statistical study. [ABSTRACT FROM AUTHOR]

Basement-involved fault geometry and kinematics has a systematic effect on the structural style of the tectonic setting. In this study, 2D and 3D seismic datasets, well data as well as thickness and depth maps were utilized to consider and reconstruct the characteristics and effects of the wrench-dominated basement-involved fault underlying the Bahregansar anticline, which is a gentle, elongated and NW-SE-trending structure in the NW Persian Gulf, on the nature of its folded strata. Moreover, using the 2D sequential restoration, the deformation of the basement structural features was modelled and analysed for its influence on the reactivation of faulting. The results show that themajor basement-involved fault, called theHendijan-Bahregansar-Nowrooz Fault (HBNF), extends along the NE-SW-trending orientation and consist of several key anticlines. The structural evolution of the Bahregansar anticline has been deeply affected by Turonian folding phase and Pliocene Zagros orogeny associated with the HBNF. In the Upper Cretaceous, the HBNF propagated upward through the overlying sedimentary sequences when the inherited normal fault contractionally reactivated in the sinistral-reverse sense as the transpression zone in response to the Neo-Tethys oceanic plate subduction under the Eurasian plate. In this regard, the NNE-SSW-trending Bahregansar anticline (i.e., Arabian trend) formed as a forced fold. Continuing oblique convergence and associated deformation was accommodated by a change in the HBNF displacement sense from sinistral to dextral movement and buckling of the Bahregansar anticline as a result of the Pliocene Zagros orogeny. [ABSTRACT FROM AUTHOR]

Despite the large number of magnetostratigraphic studies in the South Pyrenean Basin aiming to calibrate the basin chronostratigraphy and the biostratigraphic scales, the South Eastern Jaca Basin remains unexplored from this perspective, and its relation with the Ainsa Basin is not fully understood. In this work we contribute with new magnetostratigraphic data from the 950m thick Las Bellostas section, located in the northern hinge of the Balzes anticline. Well-proven primary signal (positive fold test and two pseudo-antiparallel polarities) supported by numerous primary data in the surroundings allow us building a reliable local polarity sequence of eight magnetozones (from R1 to N4). Additionally, seven new biostratigraphic samples (Nummulites and Assilina) in the lower part of the section (marine environment) allows tightening the section to the Geomagnetic Polarity Time Scale (GPTS) and proposing a refined age model for the southeastern Jaca Basin. The section starts in the Boltaña Fm., of Cuisian age (Shallow Benthic Zone, SBZ11), is followed by a sedimentary gap from C22n to C20n as witnessed by biostratigraphic data (SBZ11 underneath the hiatus and SBZ16 just atop). The deltaic Sobrarbe Fm can be tracked until the C19n (Late Lutetian). From this point (200m) until the top of the section (950m), at least, the entire C18n chron can be recognized within the molassic Campodarbe Fm (C18n.2n-C18n.1r and C18n.1n) (Bartonian) equivalent to the West to the prodeltaic Arguis marls Fm. The Middle Cusian (SBZ11) to Middle Lutetian (SBZ15) stratigraphic hiatus is, in part, enhanced by the structural position at the hinge of the Balzes anticline. These new chronostratigraphic constraints help refining the W-E and N-S stratigraphic relationships in the eastern Jaca Basin and in the Ainsa Basin. This section also allows us to accurately refine the kinematics of the rotational activity in the eastern External Sierras. The significant difference in magnetic declination along the section and neighboring paleomagnetic data from the Balzes anticline (from -70° clockwise at the base of the stratigraphic section to non-significant at the top) together with the new age model for the Eastern Jaca Basin help characterizing the rotational activity of the Balzes thrust sheet. The rotation took place between chrons C20r (Middle Lutetian; 45Ma) and C17 (Lower Priabonian 37-38Ma) in agreement to nearby structures (Boltaña, Pico del Aguila anticlines) but clearly diachronic to western ones (Santo Domingo anticline). Besides, the rotational activity seems to follow a linear and continuous pattern (velocity 9-11°/Ma, R: 0.83-0.96) in contrast to closer structures that show two distinct rotational velocities (i.e. Boltaña). These new data still let open the debate on the rotational kinematics along the South Pyrenean basal thrust. [ABSTRACT FROM AUTHOR]

Elaborated geological mapping and structural analysis of the Gulf of Suez's western side revealed two superimposed tectonic regimes; Late Cretaceous‐Early Eocene dextral transpression along ENE‐oriented deep‐seated faults and NE Oligo‐Miocene extension. Pre‐rift structures are represented by four ENE‐oriented right‐lateral strike‐slip deformation zones (DZ). Each DZ is defined by the ENE‐oriented right‐lateral strike‐slip faults, NE to ENE growth folds, and NW‐oriented normal faults. The orthogonal relation between the growth folds and NW‐oriented faults indicates their association to a strike‐slip tectonic regime. The tight overturned folds and the small angles between the growth fold axis and the principal deformation zone implies transpression rather than simple shearing. A transpressional tectonic regime with NW‐SE maximum principal stress (σ1) and NE‐SW minimum principal stress (σ3) were dominantly active during Late Cretaceous‐Early Eocene. The occurrence of three angular unconformities at different stratigraphic levels within the Upper Cretaceous‐Lower Eocene sedimentary sequences infer the deformation age. ENE anticlines have grown above the propagating deep‐seated transpressional faults, associated with continuous exhumation along their hinge zones and syntectonic deposition in the sub‐basins beyond their steep limbs. [ABSTRACT FROM AUTHOR]

This work presents data that identify a system of normal lystric domino faults, with synthetic and antithetical arrangements, at the edge of what is presumed to be a rift-type basin in northeastern Mexico. The outcrops are located within La Gavia and Arteaga anticlines, in the State of Coahuila and these localities are located paleogeographically on the eastern edge of the Coahuila Block. The structural analysis of these faults allows defining an extension vector s3 perpendicular to the edge of the Coahuila Block, trending ~ 0 °/191°-193 ° in La Gavia, and s3 ~ 0 °/200° in Arteaga. Deformation in soft "non-lithified" sediments is also present in the succession. The structural analysis of the faults and the sedimentary structures in soft sediments suggest that these deformations were synchronous to basin infilling and co-genetics. This fault system is restricted to a specific stratigraphic level; thus, it is suggested that it has a contemporary development with the clastic sedimentation of the Arcosa Patula and the Carbonera Formation during the Lower Cretaceous. It is interpreted that the extension that generated these faults and soft sediment deformation can be attributed to different causes: 1) as a consequence of regional tectonic stress during extension in rift-type environments such as those generated by the Sabinas and Central Mexico basins; 2) a steep slope of the sedimentary wedge between the Coahuila Block and the basins during rejuvenation of the relief, or, 3) the combination of both mechanisms. [ABSTRACT FROM AUTHOR]

The Bekhme Formation forms almost the bulk of the Shakrook anticline, especially the limbs. The current research deals with studying the exposed beds within the Bekhme Formation at the Shakrook anticline to check the suitability of the exposed rocks at the northeastern limb of the anticline for the cement industry. Twenty rock samples from a section which lies along a deeply cut valley that crosses the northeastern limb of the Shakrook anticline within the Bekhme Formation were collected. The channel sampling method was applied; therefore, each sample represents the concerned sampling interval and to be representative for the thickness of the sampled interval. The total thickness of the sampled section is 110 m with a covered interval of 15 m, totaling to 125 m. The collected 20 samples were prepared at the laboratory of the Koya University and were subjected to XRF test at the Tarbiat Modares University, Iran, to indicate the concentration of the main oxides (CaO, MgO, Al2O3, Fe2O3, Na2O, K2O, and SO3), and Cl and L.O.I. The indicated concentrations at each sample, from both universities, were compared and were found to be almost coinciding. The average concentrations at each sample were changed to weighted averages and the results were compared with the Iraqi standards for cement industry. The results revealed that the sampled rocks are excellent for cement production. [ABSTRACT FROM AUTHOR]

Copyright of Boletin de Geologia is the property of Universidad Industrial de Santander and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Late Cretaceous obduction of the Semail ophiolite and underlying thrust sheets of Neo-Tethyan oceanic sediments onto the submerged continental margin of Oman involved thin-skinned SW-vergent thrusting above a thick Guadalupian-Cenomanian shelf-carbonate sequence. A flexural foreland basin (Muti and Aruma Basin) developed due to the thrust loading. Newly available seismic reflection data, tied to wells in the Gulf of Oman, suggest indirectly that the trailing edge of the Semail Ophiolite is not rooted in the Gulf of Oman crust but is truncated by an ENE-dipping extensional fault parallel to the coastline. This fault is inferred to separate the Semail ophiolite to the SW from in situ oceanic Gulf of Oman crust to the NE. It forms the basin margin to a "hinterland" basin formed atop the Gulf of Oman crust, in which 5 km of Late Cretaceous deep-water mudstones accumulated together with 4 km of Miocene and younger deep-water mudstones and sandstones. Syndepositional folding included Paleocene-Eocene folds on N-S axes, and Paleocene to Oligocene growth faults with roll-over anticlines, along the basin flank. Pliocene compression formed, or tightened, box folds whose axes parallel the modern coast with local south-vergent thrusts and reversal of the growth faults. This Pliocene compression resulted in large-scale buckling of the Cenozoic section, truncated above by an intra-Pliocene unconformity. A spectacular 60-km-long, Eocene(?) to Recent, low-angle, extensional, gravitational fault, down-throws the upper basin fill to the north. The inferred basement of the hinterland basin is in situ Late Cretaceous oceanic lithosphere that is subducting northwards beneath the Makran accretionary prism. [ABSTRACT FROM AUTHOR]

The Qale-Nar oilfield is an asymmetric two-humped anticline located in the northernmost part of the Dezful embayment, in which the fractured Asmari carbonates are the primary reservoir rock. In this study, for the first time, the organic geochemistry of oils produced from the Asmari reservoir is used to investigate the reservoir continuity and possible compartmentalization. To this end, geological information from the studied oilfield was combined with bulk geochemistry (e.g., °API gravity) and molecular characteristics (e.g., gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) data) of the produced oils. Two oil samples obtained from wells 6 and 10 of the studied oilfields indicate significant differences in their bulk and molecular geochemical properties. Accordingly, a scenario was presented to better explain the reservoir charging and compartmentalization in the Qale-Nar oilfield. In this scenario, low-maturity hydrocarbon pulses first charge the eastern culmination of the Qale-Nar oilfield. The activity of a fault plane located between wells 6 and 10 could induce a barrier between the two wells. Consequently, the late hydrocarbon charges with higher maturity could only charge the compartment belonging to well 6. Therefore, well 10 could not receive these high-maturity hydrocarbon pulses due to the lack of lateral connectivity. The information obtained from this study can be of great help in future reservoir studies with important implications for field development projects and enhanced-recovery plans. [ABSTRACT FROM AUTHOR]

The western Transverse Ranges and southern Coast Ranges of California are lithologically similar but have very different styles and rates of Quaternary deformation. The western Transverse Ranges are deformed by west-trending folds and reverse faults with fast rates of Quaternary fault slip (1-11 mm/yr) and uplift (1-7 mm/yr). The southern Coast Ranges, however, are primarily deformed by northwest-trending folds and right-lateral strike-slip faults with much slower slip rates (3 mm/yr or less) and uplift rates (<1 mm/yr). Faults and folds at the boundary between these two structural domains exhibit geometric and kinematic characteristics of both domains, but little is known about the rate of Quaternary deformation along the boundary. We used a late Pleistocene sedimentary deposit, the Orcutt Formation, as a marker to characterize deformation within the boundary zone over the past 120 k.y. The Orcutt Formation is a fluvial deposit in the Santa Maria Basin that formed during regional planation by a broad fluvial system that graded into a shoreline platform at the coast. We used post-infrared-infrared-stimulated luminescence (pIR-IRSL) dating to determine that the Orcutt Formation was deposited between 119 ± 8 and 85 ± 6 ka, coincident with oxygen isotope stages 5e-a paleo-sea-level highstands and regional depositional events. The deformed Orcutt basal surface closely follows the present-day topography of the Santa Maria Basin and is folded by northwest-trending anticlines that are a combination of fault-propagation and fault-bend-folding controlled by deeper thrust faults. Reconstructions of the Orcutt basal surface and forward modeling of balanced cross sections across the study area allowed us to measure rock uplift rates and fault slip rates. Rock uplift rates at the crests of two major anticlinoria are 0.9-4.9 mm/yr, and the dip-slip rate along the blind fault system that underlies these folds is 5.6-6.7 mm/yr. These rates are similar to those reported from the Ventura area to the southeast and indicate that the relatively high rates of deformation in the western Transverse Ranges are also present along the northern boundary zone. The deformation style and rates are consistent with models that attribute shortening across the Santa Maria Basin to accommodation of clockwise rotation of the western Transverse Ranges and suggest that rotation has continued into late Quaternary time. [ABSTRACT FROM AUTHOR]

Active fold-and-thrust belts create new landslide-prone slopes during tectonic deformation propagation. However, studies on landslide distribution in newly formed fold-and-thrust belts are limited. In this study, we present a new inventory of landslides in the Kura fold-and-thrust belt, a tectonically active, but relatively low-altitude southern margin of the Greater Caucasus. The area has been tectonically framed in the last ~2–3 Ma and is represented by folds and thrusts deforming Miocene to Quaternary sediments. Through satellite imagery analysis, we mapped nearly 1600 landslides, with a quarter currently active. While landslides cover <1 % of the area, they tend to cluster at higher elevations and in regions with relatively high local relief. Landslides predominantly occur in tectonically uplifted areas, affecting the highest and steepest parts of growing anticlines and the steep slopes of incising valleys intersecting active thrust faults. Based on observed landslide distribution in folds at different stages of development, we propose a conceptual model for the temporal evolution of landslide patterns in weak sediment-based fold-and-thrust belts: 1) In the initial stages, slow-moving slope deformations affect incipient thrust fronts. With the flanks of the growing anticline lacking sufficient steepness, landslides tend to concentrate in deep valleys intersecting the uplifting hanging walls. 2) With ongoing thrust uplift, growing and steepening anticlines become more prone to planar sliding when dip slopes exceed friction angle, and valley development creates additional dip slopes, resulting in widespread landslides. 3) In the final stage, erosional decay reduces topographic relief, leading to badland formation with gully erosion and decreased landslide occurrence. • Nearly 1600 landslides have been inventoried across the actively propagating Kura fold-and-thrust belt. • Concentration of landslides within the steepest topography of the belt. • Landslides cluster within gorges that incise active thrusts and on the steep anticline flanks. • Landslides are absent within folds that are either too young or too old. [ABSTRACT FROM AUTHOR]

The coupled Markov chain (CMC) model is widely employed to simulate geological uncertainty based on sparse borehole data, owing to its simplicity, parameter efficiency, and computational effectiveness. However, the existing CMC methods exhibit limitations in accurately predicting the orientation and significant dip angle changes of soil stratigraphy. These limitations stem from their reliance on a globally constant Walther constant, resulting in generated layer boundaries converging to a fixed angle. To address these issues, this study develops a local CMC model to enhance the accuracy of predicting layer sequences and describe the geological uncertainty of complex geological structures using limited borehole and surface data. In the proposed local CMC method, the global geological profile is decomposed into interconnected fragments, guided by reference boreholes. For each CMC fragment, the likelihood of observational scenarios is determined to identify the layer orientation and optimal Walther's constant corresponding to the local geological profile. By combining the most likely realizations from all CMC fragments, the final geological profile and stratigraphic uncertainty are obtained. Illustrative case studies demonstrate that the proposed approach effectively addresses the limitations of conventional CMC models in accurately simulating significant changes in layer orientation and dip angle variations, given the same conditions of sparse borehole data. The employed localization strategy enables the prediction of geological profiles that encompass special layers such as soil interlayers, anticlines, and synclines, which cannot be well achieved by conventional CMC models. The local CMC model significantly improves the matching accuracy of geological model in situations with limited boreholes. Therefore, it plays a crucial role in the analysis of geological structures under data-scarce conditions. [ABSTRACT FROM AUTHOR]

The Laoyingqing Pb–Zn deposit is located on the southwestern margin of the Yangtze block and on the east side of the Xiaojiang deep fault in the Sichuan–Yunnan–Guizhou Pb–Zn metallogenic triangle area (SYGT). This deposit was first discovered in the silty and carbonaceous slate of the Middle Proterozoic Kunyang Group that is structurally controlled by thrust faults and anticlines. This study is aimed at investigating whether the Laoyingqing deposit has the same ore-forming age and type as other Pb–Zn deposits related to the Pb–Zn metallogenic system and prospecting prediction of the deep and peripheral areas of the deposits in the SYGT. Based on the sphalerite Rb–Sr age dating and S–Sr–Pb isotopic composition analysis of the Laoyingqing Pb–Zn deposit, the following results were obtained. First, the Rb–Sr isochron age of sphalerite is 209.8 ± 5.2 million years (Ma), consistent with the ages of most Pb–Zn deposits in the SYGT (approximately 200Ma), thereby potentially indicating that these Pb–Zn deposits may have been formed synchronously during the late Indosinian orogeny. Second, the Pb isotopic compositions of sulfides show a linear trend on the average crustal Pb evolution curve in 207Pb/204Pb vs. 206Pb/204Pb plot. In addition, Pb isotopic ratios were consistent with the age-corrected Pb isotopic ratios of basement rocks, consequently suggesting that the source of mixed crustal Pb is mainly derived from basement rocks. Combined with the initial 87Sr/86Sr ratios of sphalerite between the (87Sr/86Sr)200Ma value of the basement rocks and that of the Upper Sinian–Permian carbonates, it can be concluded that the ore-forming metals were mainly derived from basement rocks. Third, sulfur isotopic composition of sphalerite from the Laoyingqing deposits shows δ34SCDT values that range mainly from -2.62‰ to 1.42‰, which is evidently lower than the δ34SCDT values of sulfides (8–20‰) from other Pb–Zn deposits in the SYGT. This can be interpreted as a result of mixing with reduced S that was mainly derived from the thermochemically reduced S in the overlying strata and a small amount of reduced S produced by the pyrolysis of S-containing organic matter. We conclude that the Laoyingqing deposit and most of the Pb–Zn deposits in the SYGT are Mississippi Valley-type deposits, thereby providing new ideas for investigating the deep and peripheral areas of Pb–Zn deposits. [ABSTRACT FROM AUTHOR]

The paper is aimed at the basin and petroleum system modeling in the conjunction zone of the Alexander and Srednevasyugan anticlines and Ust-Tym depression during the Mesozoic-Cenozoic time. The exploration area is located in the southeastern part of the West Siberian hydrocarbon province. The present research primarily identifies the oil-window-entry time, maturity, generation points, generation power, and remaining potential of the Togur and Bazhenov source rocks. The Togur oil-window-entry time is 139.5 Ma. The Bazhenov oil-window-entry time is 99 Ma. Liquid hydrocarbons are extensively generated by the source rocks at the present time, since the Togur and Bazhenov Formations are found to be in the oil window. The significant amount of generated hydrocarbons is lost in migration processes. The source rock generation power and remaining potential are 1.1 and 1.5 billion tons of hydrocarbons, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Sciences, Islamic Republic of Iran is the property of University of Tehran and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A review and assessment of earlier studies shows that the thermal groundwater near Chongqing in the eastern Sichuan Basin of China has a unique occurrence called the 'basin-anticline outcropping' type. Its occurrence and emergence are strongly controlled by the nearly north-south trending anticlines. The basin-anticline outcropping type groundwater is similar to that of the basin type but also has the characteristics of the outcropping type because of the anticlines. The natural hot springs in the study area exist mainly in the outcropping areas of the carbonates, in the middle and the plunging ends of the anticlines where the topography was cut by rivers. They can also rise through the overlying sandstones and form up-flow springs. Geothermal wells tapping the carbonate reservoirs on the flanks of the anticlines also produce thermal groundwater. The groundwater flow can be divided into three levels: (1) shallow circulation system with groundwater of HCO3-Ca type and low TDS discharging through normal temperature springs, (2) middle circulation system with groundwater of SO4-Ca type and TDS of 2-3 g/L discharging through hot springs and (3) deep circulation system with groundwater of Cl-Na type and high TDS discharging through hot springs or wells. [ABSTRACT FROM AUTHOR]

Compressional strains may manifest along pre-existing structures within the lithosphere, far from the plate boundaries along which the causal stress is greatest. The style and magnitude of the related contraction is expressed in different ways, depending on the geometric and mechanical properties of the pre-existing structure. A three-dimensional approach is thus required to understand how compression may be partitioned and expressed along structures in space and time. We here examine how post-rift compressional strains are expressed along the northern margin of the Farsund Basin during Late Cretaceous inversion and Palaeogene–Neogene pulses of uplift. At the largest scale, stress localises along the lithosphere-scale Sorgenfrei-Tornquist Zone, where it is expressed in the upper crust as hangingwall folding, reverse reactivation of the basin-bounding normal fault, and bulk regional uplift. The geometry of the northern margin of the basin varies along strike, with a normal fault system passing eastward into an unfaulted ramp. Late Cretaceous compressive stresses, originating from the convergence between Africa, Iberia, and Europe, selectively reactivated geometrically simple, planar sections of the fault, producing hangingwall anticlines and causing long-wavelength folding of the basin fill. The amplitude of these anticlines decreases upwards due to tightening of pre-existing fault propagation folds at greater depths. In contrast, later Palaeogene–Neogene uplift is accommodated by long-wavelength folding and regional uplift of the entire basin. Subcrop mapping below a major, uplift-related unconformity and borehole-based compaction analysis show that uplift increases to the north and east, with the Sorgenfrei-Tornquist Zone representing a hinge line rather than a focal point to uplift, as was the case during earlier Late Cretaceous compression. We show how compressional stresses may be accommodated by different mechanisms within structurally complex settings. Furthermore, the prior history of a structure may also influence the mechanism and structural style of shortening that it experiences. [ABSTRACT FROM AUTHOR]

Geomorphological evidence provides significant information on the processes that govern lateral propagation of a growing active anticline. Within actively developing fold-and-thrust belts evidence can be recorded in Quaternary landforms and the drainage network. In the Kuqa fold-and-thrust belt (KFTB), located in the southern foothills of the Tian Shan mountains, we investigate the topographic and fluvial geomorphic records of the eastern part of the Qiulitage and of the Yakeng anticlines. In this study, using a morphometric approach, including the analysis of anomalies in the spatial patterns of river channels, topographic profiles along anticline crests, and the geometry of wind gaps, we speculate on the lateral propagation of these folds. We extract the drainage network related to the growth of the Yakeng and Qiulitage folds from the beginning onset of the folding (5.5 Ma ago) to its acceleration in the Late Quaternary. We examine 15 rivers and their catchments crossing the eastern segment of Qiulitage and the Yakeng anticlines. Our results demonstrate how the ridges along the eastern segment of Qiulitage and Yakeng folds feature (1) an anticline ridge with decreasing relief from the topographic crest to the plunging ends of the ridges, (2) alternating wind gaps and water gaps from west to east, (3) a drainage system closely controlled by folding and differential uplift, (4) a decrease in drainage basin maturity towards the east only, and (5) fluvial features that provide age constraints. We then document the evolution of the drainage network and provide insights on the growth history of the eastern Kuqa fold-and-thrust belt from its nucleation to its growth acceleration. The connections between the topography and the drainage allow us to present an integrated model that could explain their lateral and vertical fold growth along the two folds along their leading edges. • Growth of frontal folds in southern Tian Shan is studied via morphometric analyses. • Relationship between drainage evolution and Quaternary fold growth is demonstrated. • Development of wind and water gaps responds to fold growth and drainage evolution. • An Early Pliocene to Present morphostructural evolution scheme is proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Deep hidden gold orebodies in the Dian–Qian–Gui Golden Triangle have weak soil geochemical anomalies. • We analyzed the effectiveness and practicality of tectono-geochemistry method for weak information extraction in the area. • Tectono-geochemical data contain more significant anomalies than soil geochemical data. • Tectono-geochemical extraction reveals anomalies related to deep-seated orebodies. • We used tectono-geochemistry method to identify several future targets of deep-mineral exploration. Following decades of exploration of Carlin-type gold deposits in the Yunnan, Guizhou, and Guangxi provinces of China (known as the Dian–Qian–Gui Golden Triangle), surface mines are almost exhausted and undiscovered gold orebodies are deeply buried; thus, surficial geochemical information associated with concealed gold orebodies is poor. In this study, we compared methods of extracting this weak information based on soil geochemistry and tectono-geochemistry, and then applied the tectono-geochemical method to the Huijiabao and Nibao gold ore fields to evaluate its validity and identify favorable prospecting targets for deep-mineral exploration. We analyzed 8,842 soil geochemical samples and 4,049 tectono-geochemical samples from the Nibao gold ore field and its surroundings, and 253 tectono-geochemical samples from the Huijiabao gold ore field by statistical analysis and geochemical mapping. Tectono-geochemical samples were less abundant, accounting for only approximately 60 % of the number of soil geochemical samples; however, the number and proportion of high-value samples were greater and the elemental content was typically higher. Primary geochemical information related to deep-seated Carlin-type gold orebodies is profoundly affected by structures such as faults, anticlines, joints, and fissures, and was effectively identified by the tectono-geochemical technique, which focuses on tectonic and altered rocks. Conversely, soil geochemical information derived from these primary sources was significantly weaker because of the high mixing and homogeneity of elements during weathering. Eleven tectono-geochemical high composite anomalies of Au, Hg, Sb, As, and W were recognized in the east of the Nibao ore field, with Baogudi, Shuijingwan, Jiaozishan, Houzipo, Anzhe, and Hetaoshu predicted to be future targets of deep-mineral exploration. The Nayang–Yandengpo target was delineated according to high tectono-geochemical composite anomalies of Au, Hg, Sb, As, and Tl in the southeast part of the Huijiabao ore field, and nine concealed gold orebodies were identified at depths of 800–1,400 m through 37 boreholes, with a total gold resource of 16,338 kg and an average grade of 3.74 g/t. Successful case studies and applications demonstrate the effectiveness of tectono-geochemical information extraction method for detecting subtle signals from concealed orebodies, which will promote future deep exploration of the Dian–Qian–Gui Golden Triangle. [ABSTRACT FROM AUTHOR]

Folding earthquakes are a popular area of research in convergent orogenic belts because they can cause destruction without an obvious surface offset. The Ms 6.5 Pishan earthquake (Ms represents Richter magnitude scale), which occurred in the western Kunlun piedmont, Northwest Tibetan Plateau, caused significant property losses. Based on surface deformation data combined with earthquake relocation results, structural geology, and seismic reflection profiles, we determined that the Pishan blind thrust anticline is a seismogenic structure. The surface deformation caused by this earthquake was dominated by layer folding and surface uplift, which generated tensional ground fissures at the surface. Therefore, we suggest that the Ms 6.5 Pishan earthquake was a folding event. The Pishan earthquake only ruptured part of the Pishan anticline, and the main locked part between the Tekilik fault and the Pishan anticline did not rupture. This area of the western Kunlun range front may have significant seismic risk. [ABSTRACT FROM AUTHOR]

Seismic interpretation and petrophysical assessment of borehole logs from seven wells were integrated with the aim of establishing the hydrocarbon reserves prior to field development which will involve huge monetary obligation. Four hydrocarbon-bearing sands, namely Pennay 1, 2, 3 and 4 were delineated from borehole log data. Four horizons corresponding to near top of mapped hydrocarbon-bearing sands were used to produce time maps and then depth structural maps using checkshot data. Three major structure-building faults (F2, F3 and F5 which are normal, listric concave in nature) and two antithetic (F1 and F4) were identified. Structural closures identified as rollover anticlines and displayed on the time/depth structure maps suggest probable hydrocarbon accumulation at the upthrown side of the fault F4. Petrophysical analysis of the mapped reservoirs showed that the reservoirs are of good quality and are characterized with hydrocarbon saturation ranging from 56 to 72%, volume of shale between 7 and 20% and porosity between 25 and 31%. Pennay 2 and 3 have a better relative petrophysical ranking compared to other mapped reservoirs in the study area. Dissimilarity in the petrophysical parameters and the uncertainty in the reservoir properties of the four reservoirs were considered in calculating range of values of gross rock volume (GRV) and oil in place volume. This research study revealed that the discovered hydrocarbon reserve resource accumulations in the Pennay field for the four-mapped reservoir sand bodies have a total proven (1P) reserve resource estimate of 53.005MMBO at P90, 59.013MMBO at 2P/P50 and 65.898MMBO at 3P/P10. Reservoir C, the only interval with a gas cap, has a volume of 7737MMscf of free gas at 1P, 8893.2MMscf at 2P and 10185.2MMscf at 3P. These oil and gas volumetric values yield at 1P/ P90 total of 137.30MMBOE, 154.9MMBOE at 2P and 171.515MMBOE at 3P. Reservoirs B and D have the highest recoverable oil at 1P, 2P, and 3P values of 5.265MMBO and 10.70MMBO, 12.053MMBO and 5.783MMBO, 13.557MMBO and 6.244MMBO, respectively. [ABSTRACT FROM AUTHOR]

Site selection for the geological storage of CO2 for long timespans requires an understanding of the controls on containment, migration, and surface seepage of subsurface CO2 fluids. Evidence of natural CO2 migration from depth to the surface is documented at 270 sites from Italy, a prolific CO2 province. Previous studies indicate that CO2 delivery to and from buried structures that host CO2 accumulations is fault controlled but competing controls on the CO2 flow pathways affect the location and style of CO2 release. Here, we conduct a meta-analysis using a novel geospatial approach to statistically determine the relationship between the geological setting and structures and the CO2 seep spatial distribution and characteristics (morphological type, flux, and temperature) in Central Italy. We find that seep distribution differs on two spatial scales corresponding to the geological setting. On large scales (>5 km), seeps are isotropically distributed and align with regional structures such as anticlines, decollements, and extensional faults. On local scales (<5 km), seeps cluster and align with subsidiary geologic structures, including faults and lithological boundaries. The detailed location and flux of seeps within clusters are influenced by the regional structural domain: in the Tyrrhenian, seeps tend to be located along fault traces, whereas seeps are located as springs in the tip and ramp regions of fault scarps in the Apennines. Thus, our geospatial approach evidences, at a regional scale, how macrocrustal fluid flow is governed by deep extensional and compressional features but once CO2 reaches shallower structures, it evidences how smaller scale features and hydrogeological factors distribute the CO2 fluids in the near surface, dependent on the geological setting. This work not only demonstrates useful application of a novel geospatial approach to characterize competing crustal controls on CO2 flow at different scales but also informs the design of appropriate site characterization and surface monitoring programs at engineered carbon stores. [ABSTRACT FROM AUTHOR]

The Mountain Front Flexure marks a dominant topographic step in the frontal part of the Zagros Fold–Thrust Belt. It is characterized by numerous active anticlines atop of a basement fault. So far, little is known about the relative activity of the anticlines, about their evolution, or about how crustal deformation migrates over time. We assessed the relative landscape maturity of three along-strike anticlines (from SE to NW: Harir, Perat, and Akre) located on the hanging wall of the Mountain Front Flexure in the Kurdistan Region of Iraq to identify the most active structures and to gain insights into the evolution of the fold–thrust belt. Landscape maturity was evaluated using geomorphic indices such as hypsometric curves, hypsometric integral, surface roughness, and surface index. Subsequently, numerical landscape evolution models were run to estimate the relative time difference between the onset of growth of the anticlines, using the present-day topography of the Harir Anticline as a base model. A stream power equation was used to introduce fluvial erosion, and a hillslope diffusion equation was applied to account for colluvial sediment transport. For different time steps of model evolution, we calculated the geomorphic indices generated from the base model. While Akre Anticline shows deeply incised valleys and advanced erosion, Harir and Perat anticlines have relatively smoother surfaces and are supposedly younger than the Akre Anticline. The landscape maturity level decreases from NW to SE. A comparison of the geomorphic indices of the model output to those of the present-day topography of Perat and Akre anticlines revealed that it would take the Harir Anticline about 80–100 and 160–200 kyr to reach the maturity level of the Perat and Akre anticlines, respectively, assuming erosion under constant conditions and constant rock uplift rates along the three anticlines. Since the factors controlling geomorphology (lithology, structural setting, and climate) are similar for all three anticlines, and under the assumption of constant growth and erosion conditions, we infer that uplift of the Akre Anticline started 160–200 kyr before that of the Harir Anticline, with the Perat Anticline showing an intermediate age. A NW-ward propagation of the Harir Anticline itself implies that the uplift has been independent within different segments. Our method of estimating the relative age difference can be applied to many other anticlines in the Mountain Front Flexure region to construct a model of temporal evolution of this belt. [ABSTRACT FROM AUTHOR]