The Afyon-Akşehir and Sinanpaşa grabens,located in the eastern part of the Akşehir-Simav Fault System,are important sedimentary basins in the western Anatolia,Türkiye.This region,particularly the western of Afyon...The Afyon-Akşehir and Sinanpaşa grabens,located in the eastern part of the Akşehir-Simav Fault System,are important sedimentary basins in the western Anatolia,Türkiye.This region,particularly the western of Afyon-Akşehir Graben,is a significant region known for its geothermal potential.The study focuses on analyzing gravity data to identify structural elements and examine the geological structures in the basins.The edge detection and enhancement techniques such as total horizontal gradient,tilt angle of the total horizontal gradient,enhanced dip angle and curvature analysis were used to investigate the structural lineaments in the area.Furthermore,2D/3D gravity modeling techniques were utilized to investigate the sedimentary depths of the Afyon-Akşehir and Sinanpaşa grabens.Based on the findings from the edge detection studies,three distinct linear features were highlighted in addition to previously identified geological structures.3D gravity inversion modeling reveals sedimentary basin depths of up to 470 m in Sinanpaşa Graben and 720 m in the western Afyon-Akşehir Graben.As a result of the structural mapping and 2D/3D gravity modeling studies,a structural uplift that may be linked to geothermal activity was detected among the local depressions in the Afyon-Akşehir Graben.The obtained features may be of potential interest for geothermal exploration;therefore,further investigations using additional geophysical data are recommended.展开更多
A fault accommodation zone is a type of structure that is defined as regulating displacement and strain between faults structure.Increasing numbers of fault accommodation zones are being identified in graben basins,in...A fault accommodation zone is a type of structure that is defined as regulating displacement and strain between faults structure.Increasing numbers of fault accommodation zones are being identified in graben basins,indicating the potential exploration target and petroleum accumulation areas.This study aims to analyze the formation mechanism and development of fault accommodation zones under combined stress by a numerical simulation method considering geomechanical modeling.Using three-dimensional(3-D)seismic interpretation and fractal dimension method,exampled with the Dongxin fault zone,the fault activity and fault combination pattern were conducted to quantitatively characterize the activity difference in fault accommodation zones.Combined with mechanical experiment test,a geomehcanical model was established for fault accommodation zones in a graben basin.Integrating the paleostress numerical simulations and structural physical simulation experiment,the developmental characteristics and genetic mechanism of fault accommodation zones were summarized.Influenced by multi movements and combined stresses,three significant tectonic evolution stages of the Dongxing Fault Zone(DXFZ)were distinguished:During the E_(s)^(3)sedimentary period,the large difference in the stress,strain,and rupture distribution in various faults were significant,and this stage was the key generation period for the prototype of the DXFZ,including the FAZ between large-scale faults.During the E_(s)^(2)sedimentary period,the EW-trending symmetric with opposite dipping normal faults and the NE-SW trending faults with large scale were furtherly developed.The junction area of two secondary normal faults were prone to be ruptured,performing significant period for inheriting and developing characteristics of fault accommodation zones.During the Es1 sedimentary period,the high-order faults in the DXFZ exhibited the obvious fault depressions and strike-slip activity,and the fault accommodation zones were furtherly inherited and developed.This stage was the molded and formative period of the FAZ,the low-order faults,and the depression in the DXFZ.展开更多
Crossing conjugate normal faults(CCNFs)are extensively developed in many hydrocarbon-producing basins,generally existing in the form of incomplete CCNFs.Nevertheless,the effect of the non-conjugate zone of the CCNFs o...Crossing conjugate normal faults(CCNFs)are extensively developed in many hydrocarbon-producing basins,generally existing in the form of incomplete CCNFs.Nevertheless,the effect of the non-conjugate zone of the CCNFs on the conjugate relay zone post late tectonic action has not been previously studied.We use 3D elastic-plastic modeling to investigate the influence of incomplete(i.e.,partially intersecting)CCNFs on the pattern of deformation of strata in the intersection region.A series of model simulations were performed to examine the effects of horizontal tectonic extension,fault size,and fault depth on the deformation of conjugate relay zones of incomplete CCNFs.Our analyses yielded the following results.(1)The model of incomplete conjugation predicts a convex-up style of deformation in the conjugate graben region superimposed on overall subsidence under applied horizontal tectonic extension.(2)The degree of convex-up deformation of the conjugate graben depends on the influence of the non-conjugate zone on the conjugate relay zone,which varies with the amount of horizontal tectonic extension,fault size,and fault burial depth.(3)Our results indicate that incomplete CCNFs can form convex-up deformation,similar to that in the Nanpu Sag area and provide a sound understanding of hydrocarbon migration and accumulation.展开更多
The Acıgöl Graben in SW Turkey,ca.50-55 km in length and 11-15 km in width,formed during the Miocene to Quaternary periods.This graben is bounded by active normal faults of MaymundağıFault(MF)to the northwest and...The Acıgöl Graben in SW Turkey,ca.50-55 km in length and 11-15 km in width,formed during the Miocene to Quaternary periods.This graben is bounded by active normal faults of MaymundağıFault(MF)to the northwest and the GemişFault Zone(GFZ)to the southeast that have triggered significant earthquakes,causing considerable damage.This study focuses on the Bozkurt segment of the MF,which caused a damaging earthquake(Mw 6.0)in 2019 and another significant earthquake in 1886 during historical times.A paleoseismological trench survey along the Bozkurt segment revealed at least two faulting events,with the last event producing a vertical displacement of 0.25 m.The Optical Stimulated Luminescence(OSL)dating indicates that the last earthquake occurred 3.13±0.33 ka BP,while the penultimate earthquake occurred 4.0±0.72 ka BP.These dates correspond to a long-term slip rate of approximately 0.36±0.11 mm/a and a mean recurrence interval of 2.08 ka,short-term slip rate 0.78±0.16 mm/a and recurrence interval of 0.96 ka,and compatible with the mean sedimentation rate of 0.26 mm/a,calculated from drill logs in Acıgöl basin-fill.Considering the 6 km length of the Bozkurt segment and its vertical displacement of 0.25 m in the last event,this segment has the potential to generate earthquakes ranging from 5.6 to 5.9 Mw.Long-term slip rates derived from geomorphological data are 0.56 mm/year to the north and 0.64 mm/a to the south of the graben,indicating higher subsidence on the southern margin.These rates are in accordance with the slip rates calculated from the paleoseismological trench survey and sedimentation rate from the drill-log.These indications show that the Bozkurt segment is an active Holocene fault with relatively long recurrence intervals and low-slip rate.Consequently,the paleoseismological studies in combination with geomorphological data are important tool to assess seismic hazards and to define the characteristics of individual fault segments.展开更多
The Yitong graben is located in the northeastern segment of the Tertiary rift system in East China. The graben is bounded by a steep dipping transform fault on the northwestern side and subparallel normal faults on t...The Yitong graben is located in the northeastern segment of the Tertiary rift system in East China. The graben is bounded by a steep dipping transform fault on the northwestern side and subparallel normal faults on the southeastern side, with very thick marginal fan complexes indicating syntectonic sedimentation. The graben is infilled with Tertiary sediments up to 6 000 m thick, in which a series of different scaled hiatuses and tectonic inversion events have been discerned during hydrocarbon exploration. According to regional and local conformities, the basin infill may be divided into three tectonic sequences, among which the major sequence TS2 is further subdivided into three sequence sets and fourteen subsequences. Based on the sequence stratigraphic framework, depositional system tracts which are characterized by marginal fan complexes on both sides of basin and deep or shallow lacustrine deposits in the central part are reconstructed. The subsidence curves show that the graben had undergone several rapid subsidence episodes, which is interpreted to have been caused by multiple stretching of the lithosphere. Integrative analysis of the depositional structural features shows that the regional tectonic stress system experienced a transformation from dextral transformational shear through thermal subsidence to sinistral compressional shear with a general extensional setting. Extension and wrenching dominated the graben evolution and affected the depositional style in different evolutionary stages, the spatial configuration of depositional system and its relationship with unconformities. The conclusions have been applied with some successes to studying the reservoir and hydrocarbon source rock distribution and lithologic stratigraphic traps in this basin.展开更多
Yitong graben belongs to the north segment of the Tanlu fault belt .It was infilled with Eogene, Neogene and Quaternary clastic deposits, each Of them represents a distinct tectonic sequence.Six types of systems ass...Yitong graben belongs to the north segment of the Tanlu fault belt .It was infilled with Eogene, Neogene and Quaternary clastic deposits, each Of them represents a distinct tectonic sequence.Six types of systems association characteristics of distinct depositional systems and spatial disposition are identified in different evolutionary period of the graben.Sequence Stratigraphic framework of the graben is mainly controlled by structural framework,tectonic movement, sources supply, expanding and contracting cycle of lake, position of depositional center. The key factors are structural framework and tectonic movemeat.Through systematic analysis Of regional tectonic settings, it is recognized that Eogene tectonic sequence of Yitong graben was formed under tenso-shear regime. It includes four sequences indicating four tectonic events attributed to tectonic movement of marginal faults.Neogene tectonic sequence was formed under compresso-shear regime, which includes coarse clastic deposits with a thicknessof 0-500m.Pattern of in the Yitong graben indicates the asymmetrical subsisence of marginal faults along two sides and the complicated structural framework.展开更多
The BozdağHigh is a metamorphic core complex located between the Gediz(Alaşehir)and Küçük Menderes grabens in the Western Anatolia Extensional Province.The region is structurally controlled by low-angle...The BozdağHigh is a metamorphic core complex located between the Gediz(Alaşehir)and Küçük Menderes grabens in the Western Anatolia Extensional Province.The region is structurally controlled by low-angle Gediz Detachment Faults(GDF)and high-angle normal faults,which play a fundamental role in its geomorphological evolution.Understanding how these fault systems interact to shape uplift,drainage reorganization,and landscape dynamics remains an open scientific question.This study utilizes GIS-based morphometric analyses of 53 drainage basins and mountain fronts to quantify the spatial variations in uplift and fault activity.By integrating geomorphic indices(e.g.,χ-index,ksn,Smf,Vf)with analytical hierarchy process(AHP)models,we assess relative tectonic activity and investigate the kinematic evolution of fault-bounded blocks.Our findings reveal that the BozdağHigh experienced distinct rotational phases before and after the activation of high-angle faults,transitioning from an initial detachment-dominated extensional system to a segmented fault network.Additionally,BozdağHigh exhibits contrasting tectonic activity between its northern and southern flanks.While the northern flank,facing the Gediz Graben,experiences higher uplift rates and stronger tectonic forcing,the southern flank,adjacent to the Küçük Menderes Graben,exhibits relatively subdued tectonic activity and increased erosional modification.The western section of the eastern flank shows a more rapid uplift trend toward the east,whereas the southern flank displays significant surface tilting.Geomorphic evidence suggests that sequential fault activity and strain partitioning control differential uplift,drainage divide migrations,and basin asymmetry.Asymmetric basins in the southern sector,characterized by high hypsometric integral(HI)and low normalized steepness index(ksn)values,suggest a balance between erosional processes and tectonic uplift.In contrast,regions with ongoing rapid uplift exhibit higher ksn values and active knickpoint formation.These results provide new insights into the interaction between lowand high-angle fault systems and contribute to the broader understanding of tectonic evolution in extensional provinces.These new insights include the identification of spatially variable uplift and rotation patterns caused by sequential activation of low-and high-angle faults,revealing how block tilting and strain partitioning have shaped drainage reorganization and landscape evolution in the BozdağHigh.展开更多
The Albertine Graben is one of the most petroliferous onshore rifts in Africa. It forms the northemmost termination of the western arm of the East African Rift System. Its surface exposures were first studied by Wayla...The Albertine Graben is one of the most petroliferous onshore rifts in Africa. It forms the northemmost termination of the western arm of the East African Rift System. Its surface exposures were first studied by Wayland [1] and Pickford et al. [2] among others. Pickford et al. [2] especially developed the basic stratigraphic framework of the graben which was later modified by the government geoscientists and international oil companies using subsurface data. However, the stratigraphic units were not fully and formally described, and have been used informally in different and often confusing ways. The current study therefore aims to solve this challenge by establishing a coherent stratigraphic scheme for the entire graben through an integral study of surface and subsurface data. The study involves precise description of the type and reference sections for various formations both in exposure and wells; and has therefore led to the development of lithostratigraphic columns of different basins in the graben. The approach reveals that the Semliki area, south of Lake Albert, has the most complete sedimentary succession in the graben, spanning the period from middle Miocene （ca 15 Ma） to Recent. It also reveals that platform deposits, which form a small fraction of the thickness of the basinal succession, represent a highly condensed sequence which only saw deposition at times of Lake highstand.展开更多
文摘The Afyon-Akşehir and Sinanpaşa grabens,located in the eastern part of the Akşehir-Simav Fault System,are important sedimentary basins in the western Anatolia,Türkiye.This region,particularly the western of Afyon-Akşehir Graben,is a significant region known for its geothermal potential.The study focuses on analyzing gravity data to identify structural elements and examine the geological structures in the basins.The edge detection and enhancement techniques such as total horizontal gradient,tilt angle of the total horizontal gradient,enhanced dip angle and curvature analysis were used to investigate the structural lineaments in the area.Furthermore,2D/3D gravity modeling techniques were utilized to investigate the sedimentary depths of the Afyon-Akşehir and Sinanpaşa grabens.Based on the findings from the edge detection studies,three distinct linear features were highlighted in addition to previously identified geological structures.3D gravity inversion modeling reveals sedimentary basin depths of up to 470 m in Sinanpaşa Graben and 720 m in the western Afyon-Akşehir Graben.As a result of the structural mapping and 2D/3D gravity modeling studies,a structural uplift that may be linked to geothermal activity was detected among the local depressions in the Afyon-Akşehir Graben.The obtained features may be of potential interest for geothermal exploration;therefore,further investigations using additional geophysical data are recommended.
基金This research was supported by the Major Scientific and Technological Projects of CNPC under grant ZD2019-183-006the National Natural Science Foundation of China(42072234).The authors would like to appreciate all the people,who supported the data,testing,and analyses.Many thanks to the anonymous reviewers,whose comments improve the quality of our manuscript.
文摘A fault accommodation zone is a type of structure that is defined as regulating displacement and strain between faults structure.Increasing numbers of fault accommodation zones are being identified in graben basins,indicating the potential exploration target and petroleum accumulation areas.This study aims to analyze the formation mechanism and development of fault accommodation zones under combined stress by a numerical simulation method considering geomechanical modeling.Using three-dimensional(3-D)seismic interpretation and fractal dimension method,exampled with the Dongxin fault zone,the fault activity and fault combination pattern were conducted to quantitatively characterize the activity difference in fault accommodation zones.Combined with mechanical experiment test,a geomehcanical model was established for fault accommodation zones in a graben basin.Integrating the paleostress numerical simulations and structural physical simulation experiment,the developmental characteristics and genetic mechanism of fault accommodation zones were summarized.Influenced by multi movements and combined stresses,three significant tectonic evolution stages of the Dongxing Fault Zone(DXFZ)were distinguished:During the E_(s)^(3)sedimentary period,the large difference in the stress,strain,and rupture distribution in various faults were significant,and this stage was the key generation period for the prototype of the DXFZ,including the FAZ between large-scale faults.During the E_(s)^(2)sedimentary period,the EW-trending symmetric with opposite dipping normal faults and the NE-SW trending faults with large scale were furtherly developed.The junction area of two secondary normal faults were prone to be ruptured,performing significant period for inheriting and developing characteristics of fault accommodation zones.During the Es1 sedimentary period,the high-order faults in the DXFZ exhibited the obvious fault depressions and strike-slip activity,and the fault accommodation zones were furtherly inherited and developed.This stage was the molded and formative period of the FAZ,the low-order faults,and the depression in the DXFZ.
基金supported by the National Key Research and Development Program of China(No.2022YFF0800703)the National Natural Science Foundation of China(No.42230309).
文摘Crossing conjugate normal faults(CCNFs)are extensively developed in many hydrocarbon-producing basins,generally existing in the form of incomplete CCNFs.Nevertheless,the effect of the non-conjugate zone of the CCNFs on the conjugate relay zone post late tectonic action has not been previously studied.We use 3D elastic-plastic modeling to investigate the influence of incomplete(i.e.,partially intersecting)CCNFs on the pattern of deformation of strata in the intersection region.A series of model simulations were performed to examine the effects of horizontal tectonic extension,fault size,and fault depth on the deformation of conjugate relay zones of incomplete CCNFs.Our analyses yielded the following results.(1)The model of incomplete conjugation predicts a convex-up style of deformation in the conjugate graben region superimposed on overall subsidence under applied horizontal tectonic extension.(2)The degree of convex-up deformation of the conjugate graben depends on the influence of the non-conjugate zone on the conjugate relay zone,which varies with the amount of horizontal tectonic extension,fault size,and fault burial depth.(3)Our results indicate that incomplete CCNFs can form convex-up deformation,similar to that in the Nanpu Sag area and provide a sound understanding of hydrocarbon migration and accumulation.
文摘The Acıgöl Graben in SW Turkey,ca.50-55 km in length and 11-15 km in width,formed during the Miocene to Quaternary periods.This graben is bounded by active normal faults of MaymundağıFault(MF)to the northwest and the GemişFault Zone(GFZ)to the southeast that have triggered significant earthquakes,causing considerable damage.This study focuses on the Bozkurt segment of the MF,which caused a damaging earthquake(Mw 6.0)in 2019 and another significant earthquake in 1886 during historical times.A paleoseismological trench survey along the Bozkurt segment revealed at least two faulting events,with the last event producing a vertical displacement of 0.25 m.The Optical Stimulated Luminescence(OSL)dating indicates that the last earthquake occurred 3.13±0.33 ka BP,while the penultimate earthquake occurred 4.0±0.72 ka BP.These dates correspond to a long-term slip rate of approximately 0.36±0.11 mm/a and a mean recurrence interval of 2.08 ka,short-term slip rate 0.78±0.16 mm/a and recurrence interval of 0.96 ka,and compatible with the mean sedimentation rate of 0.26 mm/a,calculated from drill logs in Acıgöl basin-fill.Considering the 6 km length of the Bozkurt segment and its vertical displacement of 0.25 m in the last event,this segment has the potential to generate earthquakes ranging from 5.6 to 5.9 Mw.Long-term slip rates derived from geomorphological data are 0.56 mm/year to the north and 0.64 mm/a to the south of the graben,indicating higher subsidence on the southern margin.These rates are in accordance with the slip rates calculated from the paleoseismological trench survey and sedimentation rate from the drill-log.These indications show that the Bozkurt segment is an active Holocene fault with relatively long recurrence intervals and low-slip rate.Consequently,the paleoseismological studies in combination with geomorphological data are important tool to assess seismic hazards and to define the characteristics of individual fault segments.
文摘The Yitong graben is located in the northeastern segment of the Tertiary rift system in East China. The graben is bounded by a steep dipping transform fault on the northwestern side and subparallel normal faults on the southeastern side, with very thick marginal fan complexes indicating syntectonic sedimentation. The graben is infilled with Tertiary sediments up to 6 000 m thick, in which a series of different scaled hiatuses and tectonic inversion events have been discerned during hydrocarbon exploration. According to regional and local conformities, the basin infill may be divided into three tectonic sequences, among which the major sequence TS2 is further subdivided into three sequence sets and fourteen subsequences. Based on the sequence stratigraphic framework, depositional system tracts which are characterized by marginal fan complexes on both sides of basin and deep or shallow lacustrine deposits in the central part are reconstructed. The subsidence curves show that the graben had undergone several rapid subsidence episodes, which is interpreted to have been caused by multiple stretching of the lithosphere. Integrative analysis of the depositional structural features shows that the regional tectonic stress system experienced a transformation from dextral transformational shear through thermal subsidence to sinistral compressional shear with a general extensional setting. Extension and wrenching dominated the graben evolution and affected the depositional style in different evolutionary stages, the spatial configuration of depositional system and its relationship with unconformities. The conclusions have been applied with some successes to studying the reservoir and hydrocarbon source rock distribution and lithologic stratigraphic traps in this basin.
文摘Yitong graben belongs to the north segment of the Tanlu fault belt .It was infilled with Eogene, Neogene and Quaternary clastic deposits, each Of them represents a distinct tectonic sequence.Six types of systems association characteristics of distinct depositional systems and spatial disposition are identified in different evolutionary period of the graben.Sequence Stratigraphic framework of the graben is mainly controlled by structural framework,tectonic movement, sources supply, expanding and contracting cycle of lake, position of depositional center. The key factors are structural framework and tectonic movemeat.Through systematic analysis Of regional tectonic settings, it is recognized that Eogene tectonic sequence of Yitong graben was formed under tenso-shear regime. It includes four sequences indicating four tectonic events attributed to tectonic movement of marginal faults.Neogene tectonic sequence was formed under compresso-shear regime, which includes coarse clastic deposits with a thicknessof 0-500m.Pattern of in the Yitong graben indicates the asymmetrical subsisence of marginal faults along two sides and the complicated structural framework.
文摘The BozdağHigh is a metamorphic core complex located between the Gediz(Alaşehir)and Küçük Menderes grabens in the Western Anatolia Extensional Province.The region is structurally controlled by low-angle Gediz Detachment Faults(GDF)and high-angle normal faults,which play a fundamental role in its geomorphological evolution.Understanding how these fault systems interact to shape uplift,drainage reorganization,and landscape dynamics remains an open scientific question.This study utilizes GIS-based morphometric analyses of 53 drainage basins and mountain fronts to quantify the spatial variations in uplift and fault activity.By integrating geomorphic indices(e.g.,χ-index,ksn,Smf,Vf)with analytical hierarchy process(AHP)models,we assess relative tectonic activity and investigate the kinematic evolution of fault-bounded blocks.Our findings reveal that the BozdağHigh experienced distinct rotational phases before and after the activation of high-angle faults,transitioning from an initial detachment-dominated extensional system to a segmented fault network.Additionally,BozdağHigh exhibits contrasting tectonic activity between its northern and southern flanks.While the northern flank,facing the Gediz Graben,experiences higher uplift rates and stronger tectonic forcing,the southern flank,adjacent to the Küçük Menderes Graben,exhibits relatively subdued tectonic activity and increased erosional modification.The western section of the eastern flank shows a more rapid uplift trend toward the east,whereas the southern flank displays significant surface tilting.Geomorphic evidence suggests that sequential fault activity and strain partitioning control differential uplift,drainage divide migrations,and basin asymmetry.Asymmetric basins in the southern sector,characterized by high hypsometric integral(HI)and low normalized steepness index(ksn)values,suggest a balance between erosional processes and tectonic uplift.In contrast,regions with ongoing rapid uplift exhibit higher ksn values and active knickpoint formation.These results provide new insights into the interaction between lowand high-angle fault systems and contribute to the broader understanding of tectonic evolution in extensional provinces.These new insights include the identification of spatially variable uplift and rotation patterns caused by sequential activation of low-and high-angle faults,revealing how block tilting and strain partitioning have shaped drainage reorganization and landscape evolution in the BozdağHigh.
文摘The Albertine Graben is one of the most petroliferous onshore rifts in Africa. It forms the northemmost termination of the western arm of the East African Rift System. Its surface exposures were first studied by Wayland [1] and Pickford et al. [2] among others. Pickford et al. [2] especially developed the basic stratigraphic framework of the graben which was later modified by the government geoscientists and international oil companies using subsurface data. However, the stratigraphic units were not fully and formally described, and have been used informally in different and often confusing ways. The current study therefore aims to solve this challenge by establishing a coherent stratigraphic scheme for the entire graben through an integral study of surface and subsurface data. The study involves precise description of the type and reference sections for various formations both in exposure and wells; and has therefore led to the development of lithostratigraphic columns of different basins in the graben. The approach reveals that the Semliki area, south of Lake Albert, has the most complete sedimentary succession in the graben, spanning the period from middle Miocene （ca 15 Ma） to Recent. It also reveals that platform deposits, which form a small fraction of the thickness of the basinal succession, represent a highly condensed sequence which only saw deposition at times of Lake highstand.
