The Rioni foreland fold-and-thrust belt which is part of the western Greater Caucasus pro-wedge i... more The Rioni foreland fold-and-thrust belt which is part of the western Greater Caucasus pro-wedge is located between the Lesser Caucasus and the Greater Caucasus orogens and is one of the most important examples of the collision-driven far-field deformation of the Arabia-Eurasia convergence zone (Alania et al., 2022). The Rioni foreland fold-and-thrust belt sedimentary infill consists of pre-and syn-orogenic sequences. Moreover, recent GPS and earthquake data indicate that the Rioni foreland fold-and-thrust belt is still tectonically active and the earthquakes’ focal mechanisms are mainly thrust faults (e.g., Tibaldi et al., 2017; Tsereteli et al., 2016).Fault-related folding and wedge thrust folding theories were used to interpret 2D depth-migrated seismic reflection profiles and to construct the regional balanced and restored cross-sections across Rioni foreland fold-and-thrust belt. The balanced cross-section is approximately parallel to the trust transport direction and has a total length of 64 km. On the other hand, the amount of shortening obtained for this part of the regional balanced cross-section is 40% (-42.78km).The main style of the deformation within the thin-skinned Rioni foreland fold-and-thrust belt is represented by a set of growth fault-propagation folds, duplexes, triangle zone, and a series of thrust-top basins. The evolution of the trust-top basins was mainly controlled by the kinematics of thrust sequences and competing growth fault-propagation folds and building compressional structures of the Rioni foreland fold-and-thrust belt was governed by the Greater Caucasus basement crustal-scale duplexes propagation along detachment horizons within the cover-generating thin-skinned structures.Acknowledgment: This work was supported by Shota Rustaveli National Science Foundation (SRNSF) [Structural model of the Rioni foreland fold-and-thrust belt and the Southern Slope of the Greater Caucasus (The Tekhuri river gorge area) Grant #: PHDF-21-087]References:Alania, V., et al. (2022). Deformation structural style of the Rioni foreland fold-and-thrust belt, western Greater Caucasus: Insight from the balanced cross-section. Frontiers in Earth Science, 10:968386.Tibaldi, A., et al. (2017). Active inversion tectonics, simple shear folding and back-thrusting at Rioni Basin, Georgia. Journal of Structural Geology 96, 35-53.Tsereteli, N., et al. (2016). Active tectonics of central-western Caucasus, Georgia. Tectonophysics 691, 328-344.
The Lesser Caucasus (LC) double-wedge orogen accommodates the crustal shortening due to far-field ... more The Lesser Caucasus (LC) double-wedge orogen accommodates the crustal shortening due to far-field effects of the collision between the Arabian and Eurasian plates. Subsequent convergence of Arabia and Eurasian plates during the late Alpine time caused extensive intracontinental deformation in the LC. Herein we introduce the active deformation structural style of the Georgian part of the LC orogen based on seismic reflection profile, several oil-well, and surface geology data. Seismic reflection data reveals the presence of a Khrami basement thrust sheet, fault-related folds, triangle zone, and duplexes. The rocks involved in the deformation range from Paleozoic basement rocks to Pliocene-Quaternary basaltic lava flows.Pliocene-Quaternary lava flows are involved in compressional deformation and are related to an out-of-thrust sequence of the Khrami basement thrust sheet. Based on the interpreted seismic reflection profile, the crustal-scale duplex was recognized under the basement thrust sheet which propagates northward along the Early Jurassic shale layers.The structural architecture and tectonic evolution will be briefly presented and discussed in the new regional balanced and reconstructed cross-section across the axial zone and retro-wedge of the LC and published fission-track data (Gusmeo et al., 2021, 2022), as well as detailed examples of active tectonics, and seismicity (e.g., Tsereteli et al., 2016).ReferenceGusmeo, T., et al. (2022). Tectono-thermal evolution of central Transcaucasia: Thermal modelling, seismic interpretation, and low-temperature thermochronology of the eastern Adjara-Trialeti and western Kura sedimentary basins (Georgia). J. As. Earth Sci. 238, 105355.Gusmeo, T., et al. (2021). Structural inversion of back-arc basins-The Neogene Adjara-Trialeti fold-and-thrust belt (SW Georgia) as a far-field effect of the Arabia-Eurasia collision. Tectonophysics 803, 228702.Tsereteli, N. et al. (2016). Active tectonics of central-western Caucasus, Georgia. Tectonophysics 691, 328-344.
2D seismic reflection profiles revealed the presence of a triangle zone at the frontal part of th... more 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 s...
<p>In the present work we showcase a multidisciplinary study aimed at defining the ... more <p>In the present work we showcase a multidisciplinary study aimed at defining the ongoing deformation processes due to fault propagation and folding at the Tsaishi fold, western Caucasus (Georgia).</p> <p>Our approach consists in the integration of geomorphological observations, field geological-structural data and seismic reflection sections, allowing us to reconstruct a 3D model of this active fold, from depth to surface.</p> <p>The Tsaishi fold is an anticline located at the southwestern tip of the Rioni Basin uplifted area, at the foothill of the Greater Caucasus. The folding process that has been recognized started at the beginning of the Middle Miocene, although preliminary data suggest the possibility of an initial local uplift in the Oligocene. Considering field observations, we suggest that the folding process continues nowadays, giving rise to a south-verging anticline, as shown by upwarped late Quaternary river deposits.</p> <p>Integrating seismic reflection sections and field observations, we show that the fold backlimb is affected by three main back-thrusts, whereas, based on seismic sections, at the foot of the forelimb a main north-dipping thrust is very close to the surface. Where the thrust reaches the surface, we recognized the presence of a 13-km-long fault scarp (or fold scarp), where historical seismological data locate the epicenter of the strongest earthquake of the area, with Ms 6.0, the so-called Tsaishi earthquake of 1614 CE.</p>
<p>Collision and subsequent convergence of Arabia and Eurasian plates during the la... more <p>Collision and subsequent convergence of Arabia and Eurasian plates during the late Alpine time caused extensive intracontinental deformation in the Caucasus region. Inversion of back-arc basins, exhumation and crustal thickening took place in the far-field zone, forming two orogens, and leading to a convergence between the Lesser Caucasus (LC) and Greater Caucasus (GC). Continuous convergence between the LC and GC caused incremental deformation of the Rioni and Kura foreland basins. Recent GPS, earthquakes, and paleoseismic data indicate that the Kura foreland fold-and-thrust belt (KFFTB) is tectonically fairly active (e.g., Sokhadze et al., 2018; Tibaldi et al., 2020; Tsereteli et al., 2016; Stahl et al., 2022).</p> <p>In this study, we have integrated the post-stack depth-migrated 2D seismic profiles, borehole, and outcrop data to explore the structural geometry and kinematic features of the western KFFTB. Here we show the structural style of deformation of the convergence zone between the frontal part of the LC retro-wedge and the GC pro-wedge based on seismic reflection profiles. The seismic reflection profiles reveal the presence of a triangle zone and south-and north-vergent fault-related fold and south-vergent thrusts.</p> <p>In combination with surface geology and borehole data, we have analyzed along-strike variations of the south-vergent passive-back thrust and transition from the fault-propagation fold to wedge structure by using 2D seismic profiles in the western KFFTB.</p> <p>Based on the 2D seismic profiles and field data interpretations as well as our sequential kinematic modeling results, we have established the geometry and structural evolution of the LC-GC convergence zone in the western KFFTB since the Late Miocene.</p> <p>Acknowledgement: This research was supported by Shota Rustaveli National Science Foundation of Georgia (SRNSFG) [grant # YS-21-612. Geometry and kinematic evolution of frontal part of the Eastern Achara-Trialeti fold-and-thrust belt]</p>
In south-east Georgia, Plio-Pleistocene synorogenic deposits in the Didi Shiraki syncline of nort... more In south-east Georgia, Plio-Pleistocene synorogenic deposits in the Didi Shiraki syncline of north Kura foreland record the transition from foreland-basin to piggyback basin deposition on the hangingwall of the thrust. Unconformity-bounded sedimentary units within the basin thin both southward and northward onto structures generated by thrust faulting. Seismic reflection profiles and Didi Shiraki well show that Up to 750 m of Plio-Pleistocene (Akchagil-Apsheronian) strata accumulated between these structures, which consist of a ramp anticline in the south and a thrust duplex in the north. Thrust systems are represents the Tertiary strata: post-Maikopian basin-fill and Akchagil-Apsheronian growth strata (alluvial-fluvial conglomerates, gravelites and poor cemented sandstones). Sequential balanced models are illustrating the development of Didi Shiraki syncline from the seismic profiles by kink-band migration and fault-bend folding with deposition.
The Rioni foreland fold-and-thrust belt is part of the Greater Caucasus pro-wedge and is one of t... more The Rioni foreland fold-and-thrust belt is part of the Greater Caucasus pro-wedge and is one of the most important examples of the collision-driven far-field deformation of the Arabia-Eurasia convergence zone. Here we show the deformation structural style of the Rioni foreland fold-and-thrust belt based on seismic reflection profiles and regional balanced cross-section. The main style of deformation within the Rioni foreland fold-and-thrust belt is represented by a set of fault-propagation folds, duplexes, and triangle zone. The regional balanced cross-section shows that fault-propagation folds above the upper detachment level can develop by piggyback and break-back thrust sequences. Formation of fault-bend fold duplex structures above the lower detachment is related to piggyback thrust sequences. A balanced section restoration of compressional structures across the Rioni foreland fold-and-thrust belt provides a minimum estimate of shortening of −40%, equivalent −42.78 km. The syncl...
In the broader Caucasus region, multiple extrusive volcanic units are present within the Jurassic... more In the broader Caucasus region, multiple extrusive volcanic units are present within the Jurassic, Cretaceous, Eocene and Miocene sedimentary successions. Partial reworking of volcanic material from various provenance areas into Eocene, Oligocene and Miocene reservoir units is commonly observed in the Eastern Black Sea and in the Rioni, Kartli and Kura Basins of onshore Georgia. Reservoir quality has in general been negatively affected by volcanic rock fragments which may have undergone complex diagenetic alteration. However, despite concerns regarding reservoir quality, oil at the Samgori field, the largest field in Georgia (∼200 MM brl recovered), is hosted in altered Middle Eocene volcaniclastic sandstones interbedded with deep‐water turbidites. Previous studies of core material from numerous wells in this field showed that most of the oil is contained in altered, microfractured, laumontite‐rich tuffs which have fracture and cavernous net porosities averaging 12% and average permeability of 15 mD. The laumontite tuffs comprise only up to 20% of a tuffaceous sandstone section and occur as isolated lenses or pods on a sub‐seismic scale (i.e. 5‐10 m thick), causing highly variable oil productivity from one well to another.
The Rioni foreland fold-and-thrust belt which is part of the western Greater Caucasus pro-wedge i... more The Rioni foreland fold-and-thrust belt which is part of the western Greater Caucasus pro-wedge is located between the Lesser Caucasus and the Greater Caucasus orogens and is one of the most important examples of the collision-driven far-field deformation of the Arabia-Eurasia convergence zone (Alania et al., 2022). The Rioni foreland fold-and-thrust belt sedimentary infill consists of pre-and syn-orogenic sequences. Moreover, recent GPS and earthquake data indicate that the Rioni foreland fold-and-thrust belt is still tectonically active and the earthquakes’ focal mechanisms are mainly thrust faults (e.g., Tibaldi et al., 2017; Tsereteli et al., 2016).Fault-related folding and wedge thrust folding theories were used to interpret 2D depth-migrated seismic reflection profiles and to construct the regional balanced and restored cross-sections across Rioni foreland fold-and-thrust belt. The balanced cross-section is approximately parallel to the trust transport direction and has a total length of 64 km. On the other hand, the amount of shortening obtained for this part of the regional balanced cross-section is 40% (-42.78km).The main style of the deformation within the thin-skinned Rioni foreland fold-and-thrust belt is represented by a set of growth fault-propagation folds, duplexes, triangle zone, and a series of thrust-top basins. The evolution of the trust-top basins was mainly controlled by the kinematics of thrust sequences and competing growth fault-propagation folds and building compressional structures of the Rioni foreland fold-and-thrust belt was governed by the Greater Caucasus basement crustal-scale duplexes propagation along detachment horizons within the cover-generating thin-skinned structures.Acknowledgment: This work was supported by Shota Rustaveli National Science Foundation (SRNSF) [Structural model of the Rioni foreland fold-and-thrust belt and the Southern Slope of the Greater Caucasus (The Tekhuri river gorge area) Grant #: PHDF-21-087]References:Alania, V., et al. (2022). Deformation structural style of the Rioni foreland fold-and-thrust belt, western Greater Caucasus: Insight from the balanced cross-section. Frontiers in Earth Science, 10:968386.Tibaldi, A., et al. (2017). Active inversion tectonics, simple shear folding and back-thrusting at Rioni Basin, Georgia. Journal of Structural Geology 96, 35-53.Tsereteli, N., et al. (2016). Active tectonics of central-western Caucasus, Georgia. Tectonophysics 691, 328-344.
The Lesser Caucasus (LC) double-wedge orogen accommodates the crustal shortening due to far-field ... more The Lesser Caucasus (LC) double-wedge orogen accommodates the crustal shortening due to far-field effects of the collision between the Arabian and Eurasian plates. Subsequent convergence of Arabia and Eurasian plates during the late Alpine time caused extensive intracontinental deformation in the LC. Herein we introduce the active deformation structural style of the Georgian part of the LC orogen based on seismic reflection profile, several oil-well, and surface geology data. Seismic reflection data reveals the presence of a Khrami basement thrust sheet, fault-related folds, triangle zone, and duplexes. The rocks involved in the deformation range from Paleozoic basement rocks to Pliocene-Quaternary basaltic lava flows.Pliocene-Quaternary lava flows are involved in compressional deformation and are related to an out-of-thrust sequence of the Khrami basement thrust sheet. Based on the interpreted seismic reflection profile, the crustal-scale duplex was recognized under the basement thrust sheet which propagates northward along the Early Jurassic shale layers.The structural architecture and tectonic evolution will be briefly presented and discussed in the new regional balanced and reconstructed cross-section across the axial zone and retro-wedge of the LC and published fission-track data (Gusmeo et al., 2021, 2022), as well as detailed examples of active tectonics, and seismicity (e.g., Tsereteli et al., 2016).ReferenceGusmeo, T., et al. (2022). Tectono-thermal evolution of central Transcaucasia: Thermal modelling, seismic interpretation, and low-temperature thermochronology of the eastern Adjara-Trialeti and western Kura sedimentary basins (Georgia). J. As. Earth Sci. 238, 105355.Gusmeo, T., et al. (2021). Structural inversion of back-arc basins-The Neogene Adjara-Trialeti fold-and-thrust belt (SW Georgia) as a far-field effect of the Arabia-Eurasia collision. Tectonophysics 803, 228702.Tsereteli, N. et al. (2016). Active tectonics of central-western Caucasus, Georgia. Tectonophysics 691, 328-344.
2D seismic reflection profiles revealed the presence of a triangle zone at the frontal part of th... more 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 s...
<p>In the present work we showcase a multidisciplinary study aimed at defining the ... more <p>In the present work we showcase a multidisciplinary study aimed at defining the ongoing deformation processes due to fault propagation and folding at the Tsaishi fold, western Caucasus (Georgia).</p> <p>Our approach consists in the integration of geomorphological observations, field geological-structural data and seismic reflection sections, allowing us to reconstruct a 3D model of this active fold, from depth to surface.</p> <p>The Tsaishi fold is an anticline located at the southwestern tip of the Rioni Basin uplifted area, at the foothill of the Greater Caucasus. The folding process that has been recognized started at the beginning of the Middle Miocene, although preliminary data suggest the possibility of an initial local uplift in the Oligocene. Considering field observations, we suggest that the folding process continues nowadays, giving rise to a south-verging anticline, as shown by upwarped late Quaternary river deposits.</p> <p>Integrating seismic reflection sections and field observations, we show that the fold backlimb is affected by three main back-thrusts, whereas, based on seismic sections, at the foot of the forelimb a main north-dipping thrust is very close to the surface. Where the thrust reaches the surface, we recognized the presence of a 13-km-long fault scarp (or fold scarp), where historical seismological data locate the epicenter of the strongest earthquake of the area, with Ms 6.0, the so-called Tsaishi earthquake of 1614 CE.</p>
<p>Collision and subsequent convergence of Arabia and Eurasian plates during the la... more <p>Collision and subsequent convergence of Arabia and Eurasian plates during the late Alpine time caused extensive intracontinental deformation in the Caucasus region. Inversion of back-arc basins, exhumation and crustal thickening took place in the far-field zone, forming two orogens, and leading to a convergence between the Lesser Caucasus (LC) and Greater Caucasus (GC). Continuous convergence between the LC and GC caused incremental deformation of the Rioni and Kura foreland basins. Recent GPS, earthquakes, and paleoseismic data indicate that the Kura foreland fold-and-thrust belt (KFFTB) is tectonically fairly active (e.g., Sokhadze et al., 2018; Tibaldi et al., 2020; Tsereteli et al., 2016; Stahl et al., 2022).</p> <p>In this study, we have integrated the post-stack depth-migrated 2D seismic profiles, borehole, and outcrop data to explore the structural geometry and kinematic features of the western KFFTB. Here we show the structural style of deformation of the convergence zone between the frontal part of the LC retro-wedge and the GC pro-wedge based on seismic reflection profiles. The seismic reflection profiles reveal the presence of a triangle zone and south-and north-vergent fault-related fold and south-vergent thrusts.</p> <p>In combination with surface geology and borehole data, we have analyzed along-strike variations of the south-vergent passive-back thrust and transition from the fault-propagation fold to wedge structure by using 2D seismic profiles in the western KFFTB.</p> <p>Based on the 2D seismic profiles and field data interpretations as well as our sequential kinematic modeling results, we have established the geometry and structural evolution of the LC-GC convergence zone in the western KFFTB since the Late Miocene.</p> <p>Acknowledgement: This research was supported by Shota Rustaveli National Science Foundation of Georgia (SRNSFG) [grant # YS-21-612. Geometry and kinematic evolution of frontal part of the Eastern Achara-Trialeti fold-and-thrust belt]</p>
In south-east Georgia, Plio-Pleistocene synorogenic deposits in the Didi Shiraki syncline of nort... more In south-east Georgia, Plio-Pleistocene synorogenic deposits in the Didi Shiraki syncline of north Kura foreland record the transition from foreland-basin to piggyback basin deposition on the hangingwall of the thrust. Unconformity-bounded sedimentary units within the basin thin both southward and northward onto structures generated by thrust faulting. Seismic reflection profiles and Didi Shiraki well show that Up to 750 m of Plio-Pleistocene (Akchagil-Apsheronian) strata accumulated between these structures, which consist of a ramp anticline in the south and a thrust duplex in the north. Thrust systems are represents the Tertiary strata: post-Maikopian basin-fill and Akchagil-Apsheronian growth strata (alluvial-fluvial conglomerates, gravelites and poor cemented sandstones). Sequential balanced models are illustrating the development of Didi Shiraki syncline from the seismic profiles by kink-band migration and fault-bend folding with deposition.
The Rioni foreland fold-and-thrust belt is part of the Greater Caucasus pro-wedge and is one of t... more The Rioni foreland fold-and-thrust belt is part of the Greater Caucasus pro-wedge and is one of the most important examples of the collision-driven far-field deformation of the Arabia-Eurasia convergence zone. Here we show the deformation structural style of the Rioni foreland fold-and-thrust belt based on seismic reflection profiles and regional balanced cross-section. The main style of deformation within the Rioni foreland fold-and-thrust belt is represented by a set of fault-propagation folds, duplexes, and triangle zone. The regional balanced cross-section shows that fault-propagation folds above the upper detachment level can develop by piggyback and break-back thrust sequences. Formation of fault-bend fold duplex structures above the lower detachment is related to piggyback thrust sequences. A balanced section restoration of compressional structures across the Rioni foreland fold-and-thrust belt provides a minimum estimate of shortening of −40%, equivalent −42.78 km. The syncl...
In the broader Caucasus region, multiple extrusive volcanic units are present within the Jurassic... more In the broader Caucasus region, multiple extrusive volcanic units are present within the Jurassic, Cretaceous, Eocene and Miocene sedimentary successions. Partial reworking of volcanic material from various provenance areas into Eocene, Oligocene and Miocene reservoir units is commonly observed in the Eastern Black Sea and in the Rioni, Kartli and Kura Basins of onshore Georgia. Reservoir quality has in general been negatively affected by volcanic rock fragments which may have undergone complex diagenetic alteration. However, despite concerns regarding reservoir quality, oil at the Samgori field, the largest field in Georgia (∼200 MM brl recovered), is hosted in altered Middle Eocene volcaniclastic sandstones interbedded with deep‐water turbidites. Previous studies of core material from numerous wells in this field showed that most of the oil is contained in altered, microfractured, laumontite‐rich tuffs which have fracture and cavernous net porosities averaging 12% and average permeability of 15 mD. The laumontite tuffs comprise only up to 20% of a tuffaceous sandstone section and occur as isolated lenses or pods on a sub‐seismic scale (i.e. 5‐10 m thick), causing highly variable oil productivity from one well to another.
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Papers by Victor Alania