Fractal geometry is increasingly becoming a useful tool for modeling and quantifying the complex patterns of natural phenomena. The Earth's topography is one of these phenomena that have fractal characteristics. T...Fractal geometry is increasingly becoming a useful tool for modeling and quantifying the complex patterns of natural phenomena. The Earth's topography is one of these phenomena that have fractal characteristics. This paper investigates the relative sensitivity of topography to active tectonics using ASTER Global Digital Elevation Model. The covering divider method was used for direct extraction of surface fractal dimension(D surf) to estimate the roughness-surface of topography with aid of geographic information system(GIS)techniques. This evaluation let us highlight the role of the geomorphic and tectonic processes on the spatial variability of fractal properties of natural landforms.Geomorphic zones can be delineated using fractal dimension mapping in which variability of surface fractal dimension reflects the roughness of the landform surface and is a measure of topography texture. Obtained results showed this method can be a quick and easy way to assess the distribution of land surface deformation in different tectonic settings. The loose alluvial deposits and irregularities derived by tectonic activity have high fractal dimensions whereas the competent formations and higher wavelength folded surfaces have lower fractal dimensions.According to the obtained results, the Kazerun Fault Zone has a crucial role in the separation of the Zagros Mountain Ranges into the different lithological,geomorphological and structural zones.展开更多
Evaluation of active tectonism by means of geomorphic indices has provided crucial semi-quantitative data for evaluating seismic hazards in a fault zone in a semiarid area of the Zagros Mountains of Iran where tectoni...Evaluation of active tectonism by means of geomorphic indices has provided crucial semi-quantitative data for evaluating seismic hazards in a fault zone in a semiarid area of the Zagros Mountains of Iran where tectonic rates are low-to-moderate and there are few Quaternary dates. Quaternary activity along the seismically active but poorly understood Sabzpushan fault zone （SFZ） has been investigated. The SFZ consists of two dextral strike-slip faults, the Zafarabad and Kafari faults. Geomorphic indices including mountain front sinuosity, valley asymmetry factor, hypsometric integral, valley floor width to valley height ratio and stream length gradient index were used to assess the effects of active reverse faults which control the topographic relief and Quaternary activity. Geomorphometric and field evidence reveal that the Quaternary activity and topographic relief of the study area are controlled by two reverse faults, the North and South Sabzpushan reverse faults, which have formed a pop-up structure in the contractional step-over area between the Zafarabad and Kafari dextral strikeslip faults as a consequence of oblique convergence between the Afro-Arabian and Iranian plates accommodated by the North and South Sabzpushan thrust faults.展开更多
This paper tests a data mining method for evaluation of the ＂IRTA＂（Index of Relative Tectonic Activity） to investigate the impact of active tectonics on geomorphic processes and landscape development. Based upon K...This paper tests a data mining method for evaluation of the ＂IRTA＂（Index of Relative Tectonic Activity） to investigate the impact of active tectonics on geomorphic processes and landscape development. Based upon K-means clustering of six basin-related geomorphic indices（the hypsometric integral, basin asymmetric factor, drainage density, basin shape ratio, mean axial slope of the channel and topographic roughness） that represent the relative strength of active tectonic deformation on topography and morphology, the relative tectonic activity along the Kazerun Fault Zone in the Zagros Mountains of Iran may be classified into low, moderate and high relative tectonic activity zones. The results allow the identification of the clusters of similarly deformed areas related to relative tectonic activity. The utilization of geomorphic parameters as well as IRTA with comparison to the field observations exhibit change in relative tectonic activities mostly corresponding to the change in mechanism of the prominent fault zones in the study area.展开更多
Due to its strategic location, the Astara fault system （AFS）, which is located in Iran, has given rise to a number of earthquakes. In spite of its frequent seismic events, limited information is available for AFS. S...Due to its strategic location, the Astara fault system （AFS）, which is located in Iran, has given rise to a number of earthquakes. In spite of its frequent seismic events, limited information is available for AFS. Slip rate is one of the important variables for future scrutiny of seismic risk of this fault system. The main objective of this research is to study slip rates at intermediate and short terms for this fault system using geological, geodetic observations and empirical method. Using the geological data, the intermediate-term horizontal and vertical slip rates for AFS have been determined to be 2.8±0.2 and 0.27±0.03 mm/year, respectively. In addition, the short-term slip rates of the fault, based on the geodetic method （using displacement values of two GPS stations： HASH and DAMO） and assuming attenuation of 60% （to fold the sediment of South Caspian Basin and shortening of Talesh Mountain range）, determined to be 1.23±0.03 and 2.05±0.05 mm/year for the horizontal and vertical slips, respectively. Finally, evaluation of the slip rate using empirical relationship yields 10 mm/year for the entire fault system, which seems rather implausible.展开更多
The Zagros fold-thrust belt(ZFTB)formed from the progressive collision between the African-Arabian and Eurasian plates.This study focuses on the major tectonic lineaments concerned with the distribution of oilfields i...The Zagros fold-thrust belt(ZFTB)formed from the progressive collision between the African-Arabian and Eurasian plates.This study focuses on the major tectonic lineaments concerned with the distribution of oilfields in the southern Dezful Embayment as an extremely rich hydrocarbon province in the ZFTB,SW Iran.Integration of surface,near-surface and sub-surface data(e.g.,remote sensing,overburden rocks,reservoir and aeromagnetic data)were used for locating major tectonic lineaments in the study area.The results show that the southern Dezful Embayment area was influenced by tectonic lineaments oriented in the NW-SE,NE-SW,E-W and N-S trends,which are possible fault indicators corresponding to surface,shallow subsurface and basement faults.The dominant N-S and E-W tectonic lineaments possibly highlight the stress regime inherited from old structures in the Arabian Shield basement while the NE-SW,NW-SE trends are interpreted as effects of the Zagros orogeny.Generally,these tectonic lineaments influenced both the basement and sedimentary rocks and are used here to divide the belt into several faulted blocks with different structural frameworks.A clear picture of the tectonic trends influencing the Zagros fold-thrust belt oilfields as well as guidance for delineating hydrocarbon reservoirs in the future are presented.展开更多
基金the Research Council of Shiraz University which has supported the project
文摘Fractal geometry is increasingly becoming a useful tool for modeling and quantifying the complex patterns of natural phenomena. The Earth's topography is one of these phenomena that have fractal characteristics. This paper investigates the relative sensitivity of topography to active tectonics using ASTER Global Digital Elevation Model. The covering divider method was used for direct extraction of surface fractal dimension(D surf) to estimate the roughness-surface of topography with aid of geographic information system(GIS)techniques. This evaluation let us highlight the role of the geomorphic and tectonic processes on the spatial variability of fractal properties of natural landforms.Geomorphic zones can be delineated using fractal dimension mapping in which variability of surface fractal dimension reflects the roughness of the landform surface and is a measure of topography texture. Obtained results showed this method can be a quick and easy way to assess the distribution of land surface deformation in different tectonic settings. The loose alluvial deposits and irregularities derived by tectonic activity have high fractal dimensions whereas the competent formations and higher wavelength folded surfaces have lower fractal dimensions.According to the obtained results, the Kazerun Fault Zone has a crucial role in the separation of the Zagros Mountain Ranges into the different lithological,geomorphological and structural zones.
基金The Research Council of Shiraz University and Center of Excellence for Environmental Geology provided support for the project
文摘Evaluation of active tectonism by means of geomorphic indices has provided crucial semi-quantitative data for evaluating seismic hazards in a fault zone in a semiarid area of the Zagros Mountains of Iran where tectonic rates are low-to-moderate and there are few Quaternary dates. Quaternary activity along the seismically active but poorly understood Sabzpushan fault zone （SFZ） has been investigated. The SFZ consists of two dextral strike-slip faults, the Zafarabad and Kafari faults. Geomorphic indices including mountain front sinuosity, valley asymmetry factor, hypsometric integral, valley floor width to valley height ratio and stream length gradient index were used to assess the effects of active reverse faults which control the topographic relief and Quaternary activity. Geomorphometric and field evidence reveal that the Quaternary activity and topographic relief of the study area are controlled by two reverse faults, the North and South Sabzpushan reverse faults, which have formed a pop-up structure in the contractional step-over area between the Zafarabad and Kafari dextral strikeslip faults as a consequence of oblique convergence between the Afro-Arabian and Iranian plates accommodated by the North and South Sabzpushan thrust faults.
基金the Research Council of Shiraz University which has supported the project
文摘This paper tests a data mining method for evaluation of the ＂IRTA＂（Index of Relative Tectonic Activity） to investigate the impact of active tectonics on geomorphic processes and landscape development. Based upon K-means clustering of six basin-related geomorphic indices（the hypsometric integral, basin asymmetric factor, drainage density, basin shape ratio, mean axial slope of the channel and topographic roughness） that represent the relative strength of active tectonic deformation on topography and morphology, the relative tectonic activity along the Kazerun Fault Zone in the Zagros Mountains of Iran may be classified into low, moderate and high relative tectonic activity zones. The results allow the identification of the clusters of similarly deformed areas related to relative tectonic activity. The utilization of geomorphic parameters as well as IRTA with comparison to the field observations exhibit change in relative tectonic activities mostly corresponding to the change in mechanism of the prominent fault zones in the study area.
文摘Due to its strategic location, the Astara fault system （AFS）, which is located in Iran, has given rise to a number of earthquakes. In spite of its frequent seismic events, limited information is available for AFS. Slip rate is one of the important variables for future scrutiny of seismic risk of this fault system. The main objective of this research is to study slip rates at intermediate and short terms for this fault system using geological, geodetic observations and empirical method. Using the geological data, the intermediate-term horizontal and vertical slip rates for AFS have been determined to be 2.8±0.2 and 0.27±0.03 mm/year, respectively. In addition, the short-term slip rates of the fault, based on the geodetic method （using displacement values of two GPS stations： HASH and DAMO） and assuming attenuation of 60% （to fold the sediment of South Caspian Basin and shortening of Talesh Mountain range）, determined to be 1.23±0.03 and 2.05±0.05 mm/year for the horizontal and vertical slips, respectively. Finally, evaluation of the slip rate using empirical relationship yields 10 mm/year for the entire fault system, which seems rather implausible.
基金the Shiraz University Research Council which supported the study。
文摘The Zagros fold-thrust belt(ZFTB)formed from the progressive collision between the African-Arabian and Eurasian plates.This study focuses on the major tectonic lineaments concerned with the distribution of oilfields in the southern Dezful Embayment as an extremely rich hydrocarbon province in the ZFTB,SW Iran.Integration of surface,near-surface and sub-surface data(e.g.,remote sensing,overburden rocks,reservoir and aeromagnetic data)were used for locating major tectonic lineaments in the study area.The results show that the southern Dezful Embayment area was influenced by tectonic lineaments oriented in the NW-SE,NE-SW,E-W and N-S trends,which are possible fault indicators corresponding to surface,shallow subsurface and basement faults.The dominant N-S and E-W tectonic lineaments possibly highlight the stress regime inherited from old structures in the Arabian Shield basement while the NE-SW,NW-SE trends are interpreted as effects of the Zagros orogeny.Generally,these tectonic lineaments influenced both the basement and sedimentary rocks and are used here to divide the belt into several faulted blocks with different structural frameworks.A clear picture of the tectonic trends influencing the Zagros fold-thrust belt oilfields as well as guidance for delineating hydrocarbon reservoirs in the future are presented.
