Kinematic Evolution Research Articles

In-sequence tectonic evolution of Ediacaran nappes in the southeastern branch of the Brasília Orogen (SE Brazil): Constraints from metamorphic iterative thermodynamic modeling and monazite petrochronology

The metamorphic and kinematic evolution of medium-high grade rocks of the Andrelândia Nappe System (ANS), the orogenic wedge of the Southern Brasilia Orogen (SBO), was investigated in this work. Field and microstructural observations were combined with metamorphic petrology (i.e., iterative thermodynamic modeling) and monazite petrochronology to reconstruct the tectono-metamorphic history of the ANS rocks. The Liberdade Nappe experienced prograde metamorphism at ca. 610 Ma, achieving peak metamorphic conditions of ca. 650 °C and 9.5–10 kbar. This stage was followed by isothermal decompression linked to tectonic transport toward SE, at ca. 570 Ma. On the contrary, the Andrelândia Nappe experienced prograde metamorphism later, at ca. 580 Ma, reaching peak metamorphic conditions of ca. 680 °C and 11–12 kbar. The obtained results indicate that each nappe of the Andrelândia System records a single metamorphic cycle of burial and decompression, although it took place at different ages over a period of ca. 60 myr, from 630 to 570 Ma. The nappes experienced prograde and retrograde metamorphism whose ages progressively decreased toward the bottom of the nappe stack. We attribute this pattern to propagation of older buried material from the orogenic wedge (i.e., Liberdade Nappe), via thrust-and-fold, upon recently accreted rocks (i.e., Andrelândia Nappe), conducting a younger metamorphism event on the footwall of the ductile thrusted nappes. This mechanism is consistent with the ANS in-sequence fold-and-thrust architecture.

Reconciling patterns of long-term topographic growth with coseismic uplift by synchronous duplex thrusting

How long-term changes in surface topography relate to coseismic uplift is key to understanding the creation of high elevations along active mountain fronts, and remains hotly debated. Here we investigate this link by modeling the development of growth strata and the folding of river terraces above the Pishan duplex system in the southern Tarim Basin. We show that synchronous duplex thrusting of two neighboring faults with varying slip rates, associated with in-sequence propagation of the Pishan thrust system, is required to explain the presence of opposite-dipping panels of growth strata on the duplex front, and basinward migration of terrace fold crests. Importantly, this process of synchronous thrusting within the duplex reconciles the discrepancy between the deformation of terrace folds at the 10−1–100 million-year timescale and the maximum coseismic uplift of the 2015 Mw 6.4 Pishan earthquake on the frontal thrust. These results suggest that topography mismatch at different time scales can reflect the long-term kinematic evolution of fault systems. Thus, our study highlights the importance of characterizing complex subsurface fault kinematics for studying topographic growth, and motivates rethinking of the mountain building process in worldwide active fold-and-thrust belts, from short-term to long-term timescales.

Observations of a Failed Solar Filament Eruption Involving External Reconnection

We report a failed solar filament eruption that involves external magnetic reconnection in a quadrupolar magnetic configuration. The evolution exhibits three phases of kinematic evolution: a slow rise, an acceleration, and a deceleration. In the early slow rise, extreme-ultraviolet brightenings appear at the expected null point above the filament and are connected to the outer polarities by the hot loops, indicating the occurrence of a breakout reconnection. Subsequently, the filament is accelerated outward, accompanied by the formation of low-lying high-temperature post-flare loops (>15 MK), complying with the standard flare model. However, after 2–3 minutes, the erupting filament starts to decelerate and is finally confined in the corona. The important finding is that the confinement is closely related to an external reconnection as evidenced by the formation of high-lying large-scale hot loops (>10 MK) with their brightened footpoints at the outer polarities, the fragmentation and subsequent falling of the filament along the newly formed large-scale loops, as well as a hard X-ray source close to one of the outer footpoint brightenings. We propose that, even though the initial breakout reconnection and subsequent flare reconnection commence and accelerate the filament eruption, the following external reconnection between the erupting flux rope and overlying field, as driven by the upward filament eruption, causes the eruption to finally fail, as validated by the numerical simulation of a failed flux rope eruption.

Kinematics and geometry of normal faults at the margins of pull-apart basins: An example from the Dead Sea Basin

The parameters controlling the geometrical and kinematical evolution of a normal fault system along the margins of a subsiding pull-apart basin are studied using the case of the Dead Sea Basin. The Western margins of the basin consist of sub-parallel normal faults and basinward tilted blocks that evolved in a layered sedimentary sequence. The faults exhibit narrow domains of fault damage, characterized by mechanical degradation of the surrounding rock materials. The slip surfaces display oblique-normal abrasive striations and waviness. Measurements of normal-to-slip fault surface roughness at more than eight orders of length-scale magnitudes, combined with directly obtained fault dips and slip orientations, suggest that at length-scales higher than ~102 m the dominant geometry of the faults change from generally wavy with multiscale undulations to a characteristic zigzag pattern with two distinct sets. We utilize the numerical, discrete elements, DDA method to explain the structural evolution of the margins. Our results suggest that the sedimentary cover deforms as a coherent system of uniformly sized blocks, exhibiting flexure in the western margins and gravitational collapse eastward into the subsiding basin, predominantly in tilted blocks mode. These conditions explain many of the observed structures in the field, including the extensional belt and the stepped basinward block-tilting of the sedimentary cover. Comparing the wide deformation belt on the western margins of the basin to the much narrower deformation zone on the eastern margins suggests that the existence of a thick sedimentary cover and its initial structure control the width of the margins and the general mode of structural deformation.

Airborne Doppler Radar Observations of Tropical Cyclone Boundary Layer Kinematic Structure and Evolution During Landfall

AbstractAirborne Doppler radar observations of the wind field in the tropical cyclone boundary layer (TCBL) during the landfall of Hurricane Ida (2021) are examined here. Asymmetries in tangential and radial flow are governed by tropical cyclone (TC) motion and vertical wind shear prior to landfall, while frictional effects dominate the asymmetry location during landfall. Strong TCBL inflow on the offshore‐flow side of Ida occurs during landfall, while the location of the peak tangential wind at the top of the TCBL during this period is located on the onshore‐flow side. A comparison of these observations with a numerical simulation of TC landfall shows many consistencies with the modeling study, though there are some notable differences that may be related to differences in the characteristics of the land surface between the simulation and the observations here.

Tectonic-magmatic-hydrothermal interactions in a hot dry rock geothermal system: The role of the transfer and normal faults in the Acoculco caldera (Mexico)

In the Acoculco caldera (hot dry rock system) two geothermal boreholes were planned to intersect fracture systems in the carbonate basement. Even though the caldera is located in an area of active deformation with high rainfall, a scarce permeability was recognized. To shed light on this apparent mismatch, we investigate the area by integrating a structural and kinematic dataset on faults and fractures with the volcanological data. The results highlighted two main coeval fault systems, NW- and NE striking respectively, and two associated minor N-S and E-W striking sets, affecting the area of the Acoculco caldera and controlling its volcanic evolution. The kinematic analysis on fault-slip surfaces demonstrated that the NW-striking faults are characterized by two superposed movements: the first comprises right strike-slip to right lateral oblique-slip, while the second is dominantly normal. In contrast, the NE-striking structures display only dominantly normal movements. We explain the kinematic evolution by two recurring events, determined by the interplay between regional extension and uplift: when a crustal extension was dominant in the region (first kinematic event), the NW- and NE-trending structures played the role of transfer and normal faults, respectively; in contrast, when uplift predominated (second kinematic event) both the pre-existing NW- and NE-striking faults acted with normal movements. The location of eruptive centers is controlled by the permeability along the regional faults and their step-over zones. A closer analysis carried out in the surroundings of the geothermal boreholes suggests that deformation migrated northwards, and that fractures are sealed in this sector of Acoculco, thus strongly reducing permeability. In this view, the most promising areas for potential permeability at depth might occur northwards, beyond of the Acoculco caldera, and along the NW-trending structures. In conclusion, the fault kinematics is influenced by periods of increased partial melting of the lithosphere, the latter determining anomalous heat flux and uplift. This process interacts with the fluid pathways that are in turn controlled by the tectonic segmentation, and this is a new model to explain the tectonic-magmatic and hydrothermal interaction of this region.

Kinematic Evolution of a Large Paraglacial Landslide in the Barry Arm Fjord of Alaska

AbstractOur warming climate is adversely affecting cryospheric landscapes via glacial retreat, permafrost degradation, and associated slope destabilization. In Prince William Sound, Alaska, the rapid retreat of Barry Glacier has destabilized the slopes flanking the glacier, resulting in numerous landslides. The largest of these landslides (∼500 Mm3 in volume) is more than 2 km wide and has the potential to generate a tsunami that could affect nearby recreationists, marine traffic, infrastructure, natural and cultural resources, and the community of Whittier, located 60 km from the landslide. Here, we combine landslide structural and kinematic element mapping with data acquired from bi‐yearly airborne lidar, multi‐week satellite‐based synthetic aperture radar (SAR), sub‐hourly ground‐based SAR, and seismic monitoring from 2020 to 2022 to characterize this landslide and examine its evolution. While some methods serve as a snapshot in time that is a culmination of events, others emphasize the ever‐evolving nature of the landslide and associated hazards. Four major kinematic elements define the overall structure of the landslide, which vary in deformation type and rate, from creep (5 mm per day over several months) to episodic movement (2 m in 30 days) and landslide‐wide to localized events. In some areas of the landslide, short‐term deformation deviates from structures formed by cumulative movement, implying structural and kinematic evolution associated with glacier retreat. These insights are important for assessing landslide hazards and hazard evolution for large, slow‐moving bedrock landslides in actively deglaciating environments.

TRAO Survey of Nearby Filamentary Molecular Clouds, the Universal Nursery of Stars (TRAO-FUNS). III. Filaments and Dense Cores in the NGC 2068 and NGC 2071 Regions of Orion B

We present the results of molecular line observations performed toward the NGC 2068 and NGC 2071 regions of the Orion B cloud as the TRAO-FUNS project to study the roles of the filamentary structure in the formation of dense cores and stars in the clouds. Gaussian decomposition for the C18O spectra with multiple velocity components and the application of a friends-of-friends algorithm for the decomposed components allowed us to identify a few tens of velocity-coherent filaments. We also identified 48 dense cores from the observations of N2H+ using a core finding tool, FellWalker. We performed a virial analysis for these filaments and dense cores, finding that the filaments with N2H+ dense core are thermally supercritical, and the filaments with a larger ratio between the line mass and the thermal critical line mass tend to have more dense cores. We investigated the contribution of the nonthermal motions in dense cores and filaments, showing the dense cores are mostly in transonic/subsonic motions while their natal filaments are mostly in supersonic motions. This may indicate that gas turbulent motions in the filaments have been dissipated at the core scale to form the dense cores there. The filaments with (dynamically evolved) dense cores in infalling motions or with NH2D bright (or chemically evolved) dense cores are all found to be gravitationally critical. Therefore, the criticality of the filament is thought to provide a key condition for its fragmentation, the formation of dense cores, and their kinematical and chemical evolution.

A Deformed Wedge‐Top Basin Inverted During the Collapse of the Variscan Belt: The Permo‐Carboniferous Lorraine Basin (NE France)

AbstractA new structural model is presented for the Permo‐Carboniferous Lorraine Basin (NE France), a major intramountain basin that developed during the latest stages of the Variscan orogeny (ca. 315–270 Ma). Digitalized well logs and reprocessed seismic data were used to decipher the kinematic evolution of this basin located along the Rhenohercynian orogenic suture zone. The basin was initiated during the late collision stage (Early to Middle Pennsylvanian) in a wedge‐top position upon the Saxothuringian retro‐wedge. The syn‐orogenic sequence is delimited to the north by the major SE‐verging Metz Thrust, which is part of the backthrust system that propagated during Middle Pennsylvanian (Late Westphalian). Seismic data provide evidence of negative tectonic inversion, allowing the formation of syn‐rift depocenters (Late Pennsylvanian‐Early Permian) above the former anticlines. Erosion of these anticlines results in a major unconformity marking the onset of post‐orogenic collapse. The late Early Permian shortening (Saalian phase) is suggested to reactivate former thrusts and normal faults, thus generating late uplift of the basin. The post‐orogenic phase is complex and diachronous at basin scale, and both compression and extension can be recorded in the same area over a short period (<10 Myr). The Late Carboniferous negative tectonic inversion along the Rhenohercynian suture zone is proposed to result from the lithospheric delamination of the Variscan orogenic roots. The associated upwelling of asthenospheric material is recorded by intense magmatic activity, and can be, in turn, considered as the main trigger for the subsequent thermal subsidence of the Mesozoic Paris Basin.

The Impulsive Acceleration of a Solar Filament Eruption Associated with a B-class Flare

The eruption of magnetic flux ropes (MFRs), often taking filaments together, leads to coronal mass ejections (CMEs). Theoretical studies propose that both the resistive magnetic reconnection and the ideal instability of an MFR system can release magnetic-free energy and accelerate CMEs (i.e., MFRs or filaments) during eruptions. Observations find that the full kinematic evolution of CMEs usually undergoes three phases: the initiation phase, impulsive acceleration phase, and propagation phase. The impulsive acceleration phase often starts and ceases simultaneously with the flare onset time and peak time, respectively. This synchronization can be explained by the positive feedback relationship between the acceleration of CMEs and flare magnetic reconnection, and suggests that the reconnection has the dominant contribution to the acceleration of CMEs. It is rare to see strong evidence that supports the dominant contribution of ideal instability to the acceleration. In this paper, we report an intriguing filament eruption that occurred on 2011 May 11. Its complete acceleration is well recorded by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. The kinematic analysis shows that the impulsive acceleration phase starts and ceases obviously earlier than the flare onset time and peak time, respectively, which means a complete asynchronization between the impulsive acceleration phase and flare rise phase, and strongly supports that the ideal instability plays a dominant role in this impulsive acceleration. Furthermore, the accompanied flare is a B-class one, also implying that the contribution of reconnection is negligible in the energy release process.

Two-phase kinematic evolution of the Qilian Shan, northern Tibetan Plateau: Initial Eocene−Oligocene deformation that accelerated in the mid-Miocene

The Cenozoic growth of the Tibetan Plateau and the distribution of deformation across it are a consequence of India-Asia collision and continued convergence, which have implications for studies of continental tectonics. The spatio-temporal development of Cenozoic deformation along the northern margin of the plateau is an important issue that can be better understood by testing various models of plateau growth. The northern Tibetan Plateau is bounded by the Cenozoic Qilian Shan thrust belt and the Haiyuan left-slip fault. We conducted geologic mapping, field observations, electron spin resonance (ESR) dating, and apatite (U-Th)/He (AHe) and apatite fission-track (AFT) analysis in the Qilian Shan thrust belt to improve our understanding of the timing of brittle faulting and range exhumation in the northern Tibetan Plateau. We document the first direct age constraints for Oligocene deformation within the central Qilian Shan via ESR dating, which correlates with AHe-AFT cooling ages in adjacent ranges. We demonstrate that the Qilian Shan thrust belt experienced a two-phase growth history, including Eocene−Oligocene fault-related uplift shortly after the India-Asia convergence, and mid-Miocene regional overprinting deformation that reactivated the proximal thrust faults. This deformational pattern suggests that the Qilian Shan thrust belt has experienced out-of-sequence development since the Eocene−Oligocene and has persisted as the stationary northeastern boundary of the Himalayan-Tibetan Orogen throughout the Cenozoic. The Paleozoic Qilian suture systems acted as a pre-existing weakness and played a decisive role in controlling the lithospheric rheology, which therefore impacted the timing, pattern, and strain distribution of Cenozoic deformation across the northern Tibetan Plateau.

The kinematics of a salt sheet recorded in an array of distorted intrasalt stringers (Les Avellanes Diapir – South-Central Pyrenees)

Stringers represent fragments of competent, brittle layers, formerly interstratified within a layered evaporite sequence (LES) that are entrained and deformed by viscous flow. To resolve the impact of the stringers on the deformation style of an extrusive salt sheet, an array of decameter-thick, carbonate stringers, preserved in the caprock matrix of the Les Avellanes Diapir (South-Central Pyrenees) was analysed. The diapir exposure was mapped in detail to produce a cross-section that shows the stringer assemblage. To understand the dynamic behaviour of stringers, this natural prototype has been reproduced using scaled analogue models. In the model, stringers were carried into the salt sheet, rotating and deforming while migrating toward the sheet front. The array of stringers can be divided into the following three structural domains: 1) a feeder domain mainly hosting vertical stringers parallel to the stem wall that rotate to a subhorizontal orientation as they approach the allochthonous sheet, 2) a sheet domain containing stack-like sets of subvertical and overturned, to subhorizontal stringers, as well as isoclinally and recumbently folded stringers, and 3) a sheet front domain characterised by stringers dipping toward the salt sheet front. Compartmentalization of the horizontal flow by the transported stringers controlled the deformation in the caprock matrix above. Finally, the similarity between the field observations and the model is evaluated and discussed to shed light on the Les Avellanes Diapir kinematic evolution.

Kinematic Evolution of the Nyakong-Manyi Shear Zone (Adamawa, Cameroon): Constraints from Field Observations and Microstructures, and Implication for Metamorphic P-T-t Estimation

Kinematic Evolution of the Nyakong-Manyi Shear Zone (Adamawa, Cameroon): Constraints from Field Observations and Microstructures, and Implication for Metamorphic P-T-t Estimation

Structural style of Taq Taq Anticline in the Zagros Fold-Thrust Belt in the Iraqi Kurdistan Region from the Integrated Surface and Subsurface Data

Taq Taq is a prolific oilfield in the Kurdistan Region of Iraq. It consists of a longitudinal double plunged anticline that is located within the Foothill Zone of the Zagros Fold-Thrust Belt. We studied the structural style of the Taq Taq Anticline from three balanced and retro-deformed structural cross-sections constrained by the integration of intensive surface geological observations, seismic sections and well data. The sections were constructed to understand the variation in the structural architecture of the anticline both along strike and up-section, and to describe the kinematic evolution and plausible fold model of the structure. The anticline exhibits symmetrical to slightly reverse asymmetry, and bounded by two main blind thrust faults (fore- and back-thrusts) that dip toward each other. The thrusts are interpreted to be detached along a deep-lying décollement in the KurraChine Formation (Upper Triassic) without involving basement fault. Thus, the structure can be considered as a faulted-detachment fold anticline with pop-up geometry. The average horizontal shortening value ranges between 5.6% and 8.1% with an average value of ca. 6.7%. Generally, the shortening values decrease gradually to the up section due to slight decrease in the fault offset value up-section. The increase in deformation intensity, asymmetry, shortening rate and geometry variation toward SE is mainly related to displacement variation on individual thrusts, fold wavelength and amplitude, or may be related to the effect of strike-slip fault. Therefore, the middle and NW parts of the structure can be considered as a better well location for the Taq Taq crestal reservoir.

Segmentation and lateral growth of intracratonic strike-slip faults in the northern Tarim Basin, NW China: influences on Ordovician fault-controlled carbonate reservoirs

Intracratonic strike-slip faults have been recognized as a major factor controlling the formation of fracture-cave carbonate reservoirs in deep buried basins, yet which properties and how the strike-slip faults influence reservoir distribution and their connectivity are still ambiguous. This uncertainty significantly restricts hydrocarbon exploration and development, such as in the Fuman oilfield, northern Tarim Basin, NW China. Using a high-resolution 3D seismic reflection survey and borehole data, we investigated the geometry and kinematic evolution of the FI17 fault zone in the Fuman oilfield. This fault zone is characterized by a single fault zone, pop-up or pull-apart structures, right-stepping en echelon normal faults, and much smaller displacement (<30 m) normal fault arrays from bottom to top. The FI17 fault zone consists of four genetic segments, including the extensional strike-slip duplex, Riedel left-lateral shear, right-stepping horsetail splay, and horizontal slip segments in map view. In particular, the formation of the ∼18 km Riedel shear zone is characterized by the growth and linkage of segmented shear faults (synthetic and secondary synthetic shears). We observed that the large-scale fault-controlled fracture-cave reservoirs are distributed in positions with wider fault zones, which are characterized by overlapping of neighboring secondary shear faults. Furthermore, the reservoir width examined in this study is natural logarithmic correlated (positively) to the fault zone width. The reservoirs linked by the same shear faults show better internal connectivity. The spatial coherence between fault geometry and reservoir features indicates that segmentation and lateral growth of intracratonic strike-slip faults controls the occurrence of fracture-cave reservoirs, which may provide support for reservoir prediction in the Fuman oilfield and other deeply buried fault-controlled carbonate reservoirs in general.

Structural geometry and kinematic evolution of the central Canadian Rocky Mountain Foothills fold-and-thrust belt: Complex kinematic relationships controlled by detachment utilization

Abstract Balanced regional cross sections based on surface, seismic, and subsurface data show that the thin-skinned fold-and-thrust belt in the Rocky Mountain Foothills of the Kakwa area of the central Canadian Rockies consists of a lower buried thrust belt developed in Paleozoic and Triassic strata and an upper exposed faulted fold belt of Jurassic to Cretaceous strata. Changes in fold wavelength, amplitude, and geometry with stratigraphic level indicate that multiple detachments were utilized in the upper faulted fold belt. Exposed folds are chevron or box shaped. Most appear to be detachment or fault propagation folds formed by fault-to-fold displacement transfer. Geometric and kinematic relationships in the upper faulted fold belt vary from thrust faults congruently folded by underlying folds (early fault) to folds abruptly truncated by thrust faults (late fault). In contrast, folding of thrust sheets in the buried thrust belt is consistent with in-sequence deformation for all faults except one. A sequential restoration of the balanced regional cross section shows that the variable kinematic relationships observed in the upper faulted fold belt can be explained by changes in the detachment level utilized by successive faults as they climbed out of the buried thrust belt. Chevron-folded thrust faults indicate a younger fault with associated fault displacement transfer folds formed in the footwall of an older fault. These folded thrusts formed by in-sequence faulting and utilization of successively higher detachment levels. Late faults that truncate preexisting folds required out-of-sequence (hinterlandward) utilization of a higher detachment level, and they illustrate another mechanism by which critical taper is maintained in a fold-and-thrust belt.

Comparative study of the heavy-quark dynamics with the Fokker-Planck equation and the Plastino-Plastino equation

The Fokker-Planck Equation (FPE) is a fundamental tool for the investigation of kinematic aspects of a wide range of systems. The Plastino-Plastino Equation (PPE) is the correct generalization describing the kinematic evolution of complex systems consistent with q-statistics. In the present work, we use this particular problem to compare the results obtained with the FPE and the PPE, and discuss the different aspects of the dynamical evolution of the system according to the solutions for each equation. We observe clear differences in the solutions for all the cases studied here and discuss possible experimental investigations that can indicate which of those equations better describes the heavy-quark kinematics in the medium. The results obtained here have implications in the study of anomalous diffusion in porous and granular media, in Cosmology and Astrophysics. The obtained results reinforce the validity of the relation (q−1)−1=(11/3)Nc−(4/3)(Nf/2), where Nc and Nf are, respectively, the number of colours and the effective number of flavours. This equation was recently established in the context of a fractal approach to QCD in the non-perturbative regime.

The influence of basal detachment strength on formation of the southwestern Sichuan fold-thrust belt: insights from discrete-element numerical simulations

Introduction: The southwestern Sichuan fold-thrust belt (SWSB) is a duplex detachment system and features the basal Precambrian detachment at a depth of approximately 15–17 km and the upper Mid-Triassic detachment. Moreover, the SWSB undergoes forward-breaking propagation during the Cenozoic. To date, the mechanism and kinematic evolution governing the SWSB in this thrusting deformation as well as the way the two detachments control the structural deformation pattern of the SWSB remains unknown.Methods: In this work, three discrete-element numerical models with the same strong upper detachment but basal detachments with different mechanical strengths and thicknesses were designed to study the deformation of the SWSB.Results: The results indicate that for the Model I with a strong frictional basal detachment with thickness of 500 m, most deformation and thrust faults concentrate near the mobile backwall. Model I exhibits characteristics such as linearly increasing wedge height and stepwise increasing wedge width and slope angle. For the Model II with a modest frictional basal detachment with thickness of 500 m, the strain and deformation propagate into the foreland quickly and multiple back-thrust and thrust faults form on the upper detachment in the second thrusting period. The first thrusting period in Model II, exhibits similarities with Model I. However, in the second period, the wedge reaches a stable state, and its geometry remains constant. In this stage, the deformation propagates along the shallow detachment into the right side of the model. The geometry and activity of thrust faults in the foreland differ significantly in the model III with a modest frictional basal detachment but a greater thickness. Two additional pop-up structures are generated in the second period in this model. The first half of the first thrusting period is similar to the first two models. In the second half of the first period and the second period, the wedge is in a stable state. In the first stage of the shortening, all models undergo a transition from a subcritical state to entering a supercritical state, which indicates that the deformation is progressing rapidly along the basal detachment towards the right side of the model.Discussion: The results of Model III are consistent with the deformation pattern of the SWSB. The study of the kinematics and interaction between two detachments could help hydrocarbon exploration beneath the upper detachment.

Coupled CFD-DEM simulation of submarine landslide movement behavior

Submarine landslide is a common disaster geological phenomenon in the ocean, which can be destructive to underwater infrastructure. Therefore, it is necessary to simulate the evolutionary behavior of submarine viscous landslides. In this paper, computational fluid dynamics (CFD) and discrete element method (DEM) are used to establish the fluid-solid coupling model of water-particle interaction. Firstly, the inter-particle cohesion model is introduced to train the coupled CFD-DEM analysis of the kinematic evolution process, and at the same time, two typical cases are carried out to verify the analysis. In the experimental simulation, the kinematic and morphological characteristics of the submarine landslide were simulated considering the viscous effect and initial velocity of the landslide, and the influence mechanism of the landslide motion and evolution process was investigated in depth. The results show that the coupled method can better simulate the motion of submarine landslide, and the viscous effect of the landslide has a significant influence on its kinematic and morphological characteristics, and the initial velocity also significantly affects the evolution and distribution characteristics of the particle flow field of each part of the landslide in the process of motion. This study is important for the simulation and effective prediction of the kinematic evolution process of real submarine landslides.

Interpretation and analysis of seismic and analog modeling data of triangle zone: a case study from the frontal part of western Kura foreland fold-and-thrust belt, Georgia

2D seismic reflection profiles revealed the presence of a triangle zone at the frontal part of the western Kura foreland fold-and-thrust belt of the pro-wedge of the Greater Caucasus. To understand the triangle zone geometry, seismic interpretations should be substantiated by forward kinematic modeling, supported by analog experiments. This study presents a new structural model for the region by integrating field observations, well data, and seismic reflection data. East-West directed along-strike structural variation of the frontal thrust is observed on the interpreted seismic profiles which affected the fold geometry. The Bitsmendi breakthrough fault-propagation fold gradually transits into a wedge structure in the W-E direction and is represented by the triangle zone. The seismic profiles interpretation results completely match with analog models of similar triangle zones. The analysis of the experimental results helps us to further understand the kinematic evolution of natural systems and improve seismic interpretation. The triangle zone developed in the western part of the Bitsmendi breakthrough fault-propagation fold is related to double fault-bend fold structural wedges and is characterized by the presence of passive, and active wedges, and passive-backthrust and passive-forethrust.