Neotectonism occurred intensively in the Bozhong depression in the Bohai Bay Basin, which was reflected vertically by dramatic subsidence and a number of uplifts and laterally by notable fault movements. This particul...Neotectonism occurred intensively in the Bozhong depression in the Bohai Bay Basin, which was reflected vertically by dramatic subsidence and a number of uplifts and laterally by notable fault movements. This particularity has resulted in the special petroleum geological conditions of the Bozhong depression which are different from those of adjacent lands. For example, the source rocks of the Shahejie Formation were overpressured and hydrocarbon generation occurred in the late stage; the Dongying Formation was deeply buried below the hydrocarbon-generating threshold, therefore there were sufficient oil sources. The rapid subsidence led to starved sedimentation of the Guantao Formation fine sandstone and the regional Minghuazhen Formation lacustrine shale, which formed the Neogene regional reservoir-caprock association. The active faults formed in the neotectonism became passages for oil to migrate from the Paleogene to Neogene. The traps formed by late fault activity and accompanied anticlines provided spaces for the formation of reservoirs. All the above factors match well with one another in the Bozhong depression, providing favorable conditions for the formation of a series of large oilfields in the region展开更多
Late-stage is defined here as the period when Neotectonism occurred since 5.1 Ma. Most petroliferous basins in China lie in the areas where Neotectonism occurred intensively. In recent years, Chinese petroleum geologi...Late-stage is defined here as the period when Neotectonism occurred since 5.1 Ma. Most petroliferous basins in China lie in the areas where Neotectonism occurred intensively. In recent years, Chinese petroleum geologists have paid much attention to late-stage petroleum accumulation. The PL19-3 giant oilfield is situated where faulting activities occurred violently during Neotectonism. To understand the mechanism of lat-stage rapid accumulation, we discussed the most important aspects responsible for the formation of the giant oilfield, including oil generation, active oil-source rock occurrence, fault activity and fault conduits, late-stage rapid oil injection as well as the distinguishing indicators. This study shows that: (1) sufficient oil was supplied to the PL19-3 field since 5.1 Ma because the PL19-3 structure was surrounded by four sags in which three intervals of high-quality source rocks remained active during Neotectonism; (2) densely distributed faults and high porosity/permeability sandstone carrier beds comprised the effective conduit system for oil migration and injection; (3) oil migrated along the faults and charged the PL19-3 structure rapidly by means of seismic pumping which was triggered by frequent earthquakes during Neotetonism. It is documented that elevated reservoir temperature, abnormal geothermal gradients and abnormally high homogenization temperatures of the fluid inclusions are the indicators for late-stage rapid oil accumulation.展开更多
This paper aims to unveit neotectonic imprints in topography, drainage and sediments in the 46.25 km tong course of the River Chet from its source down to its attuvial fan at the base of the Himatayan Mountain Front i...This paper aims to unveit neotectonic imprints in topography, drainage and sediments in the 46.25 km tong course of the River Chet from its source down to its attuvial fan at the base of the Himatayan Mountain Front in the Darjeeting-Jatpaiguri districts of India. A semi-circutar ridge detimits its primary catchment. Within confinement of this watershed basin the drainage pattern is composite being convergent atong the periphery and divergent on a butte inside. AtE these geomorphic neotectonic imprints are accom- panied by ramp and fiat structures and spectacutar mytonitization of rocks. High hypsometric index and convex shape of the hypsometric curve derived from the centrat near-straight course of the river between the primary catchment and the Main Frontat Thrust （MFT） atso reftects tectonic youthfutness of the river course. It is wett manifested atso in widety variabte stream index and stream gradient index ratios （SL/K） often exceeding 2. In response to neotectonism, this river course as a whore shifted westward between 1962 and 2007. Maximum reduction of the stream gradient on top of the MFT is etoquent enough about recent uptift of the thrust ridge. The high average stope gradient of canyon watt about 45.68° is wett consistent with this uptift. Very tow channet-width/vaUey-height ratio along the river further corroborates the uptift. The attuviat fan system of the River Chet is comprised of five morphogenetic fans stacked one above another with a tendency to shrink and shift progressively upstope. They differ from each other in terms of titt, axiat orientation, primary depositionat surface gradient and convexity in transverse section and thus present a writ of ongoing tectonism. Progressive upward increase in the share of distat crystattine rocks in ctast composition within attuviat fan package is a dear proxy for southerty advancement of the MFT. Concomitant increase in maximum ctast size is in good agreement with sediment source uptift. Art the five fans are, however, dormant now. Present-day River Chet deeply incises through ate of them and suggests further basement uplift in the context of frequent evidences of neotectonism att around, atthough the rote of climate remains uncertain in absence of adequate data.展开更多
This research investigates dynamic earth processes within the South Setifian allochthonous ensemble,providing insights into landscape evolution and seismotectonic activity within the Tellian mountain chain.Focusing on...This research investigates dynamic earth processes within the South Setifian allochthonous ensemble,providing insights into landscape evolution and seismotectonic activity within the Tellian mountain chain.Focusing on the Jebel Gustar and Kef Lahmar area,which includes 14 sub-basins,this research uses a DEM-based technique to assess Holocene activities,lineament characteristics,and stream systems.Five geomorphic indices are used to assess relative active tectonics:the stream lengthgradient index(SL),drainage basin asymmetry(AF),valley-floor width to valley height ratio(VF),drainage basin shape(BS),and mountain front sinuosity(SMF).A weighted overlay of these five indices produces the Index of Relative Active Tectonics(IRAT)map.The findings reveal significant neotectonic activity in the study area,supported by profound basement faulting.This research highlights the morpho-structural processes and neotectonics activity in the Jebel Gustar,providing a framework for investigating the evolution of this structure.Additionally,it enhances comprehension of the interactions between the alpine range's internal zones in Eastern Algeria and the Atlasic domain.This study proposes a systematic approach to evaluate the tectonic and geomorphological dynamics of the South Setif region.展开更多
Field analysis and differential interferometry derived from Synthetic Aperture Radar （PALSAR） of the epicentral area of the May 12 2008 Mw 8.0 Wenchuan （汶川） earthquake zone reveal details about fault ruptures an...Field analysis and differential interferometry derived from Synthetic Aperture Radar （PALSAR） of the epicentral area of the May 12 2008 Mw 8.0 Wenchuan （汶川） earthquake zone reveal details about fault ruptures and ground displacements, with field-documented vertical offsets reaching 12 m along the trace of the main fault rupture, and PALSAR-measured horizontal displacements reaching 12.3 m. We document slip indicators on the fault scarp that show initially sub-horizontal then progressively steeper slip increments with time along the same fault during the 2 min earthquake, suggesting that the rupture propagated as a mixed Mode Ⅱ-Ⅲ fracture, with strike-slip movement at the tip directing energy from the initial rupture to points north of the epicenter, followed by vertical displacement in the interior of the slipped region. Field, seismic, and PALSAR-measured displacements are dominantly thrust near the epicentral region, and dextral in northeasterly areas, showing that slipwas partitioned along the fault in space and time during the earthquake. The changing slip directions may correlate with three main pulses of energy release at 0, 23, and 57 s during the earthquake as recorded by seismograms. The earthquake generated massive landsfides 〉100 km north of the epicenter along the trace of the fault. These massive sturzstroms formed where entire mountainsides collapsed and moved at high velocity down populated mountain valleys, jumping smaller mountains and ricocheting off steep canyon walls. These avalanches rode on cushions of water and compressed air that generated air blasts from beneath the debris, knocking down trees high on opposing mountain slopes. The concentration of massive landslides and ground deformation so far north of the epicenter was related to the Mode Ⅱ-Ⅲ fracture propagation focusing seismic energy along the fault towards the north, explaining why so much devastation occurred 〉100 km from the epicenter, such as in the destroyed city of Beichuan （北川）. Understanding near-surface earthquake processes and geological hazards associated with massive earthquakes in populated mountainous areas has the potential to save many lives in the future.展开更多
Neotectonic movement refers to the tectonic movement that has happened since the Cenozoic, which is the latest movement. It has the most important influence on the basins in west China, especially on the hydrocarbon a...Neotectonic movement refers to the tectonic movement that has happened since the Cenozoic, which is the latest movement. It has the most important influence on the basins in west China, especially on the hydrocarbon accumulation in the western foreland basins. We determined the time of neotectonic movement in the Kuqa Foreland Basin, which began from the Neogene, and analyzed the patterns of movement, which were continuous and fast subsidence in the vertical direction and intense lateral compression. The structure styles are that the faulting is weakened and the folding is strengthened gradually from north to south. We studied the control of neotectonic movement on the hydrocarbon accumulation process and model in the Kuqa Foreland Basin with basin simulation technique. The largest subsidence rate of the Kuqa Foreland Basin reached 1,200 m/Ma during the neotectonic movement, leading to rapid maturing of source rock within 5 Ma and a large quantity of hydrocarbon being generated and expelled. The thick neotectonic strata can form high quality reservoirs with the proved gas and oil reserves accounting for 5% and 27% of the total reserves, respectively. 86% of the structural traps were formed in the neotectonic movement period. The faults formed during the neotectonic movement serve as important migration pathways and they exist in the region where the hydrocarbon reservoirs are distributed. Abnormally high pressure caused by the intense lateral compression, thick neotectonic strata deposition and rapid hydrocarbon generation provide driving force for hydrocarbon migration. The accumulation elements match each other well over a short period, leading to many large gas fields formed later in the Kuqa Foreland Basin.展开更多
The Late Cenozoic basins in the Weihe-Shanxi Graben, North China Craton are delineated by northeast-striking faults. The faults have, since a long time, been related to the progressive uplift and northeastward expansi...The Late Cenozoic basins in the Weihe-Shanxi Graben, North China Craton are delineated by northeast-striking faults. The faults have, since a long time, been related to the progressive uplift and northeastward expansion of the Tibetan Plateau. To show the relation between the basins and faults, two Pliocene-Pleistocene stratigraphic sections （Chengqiang and Hongyanangou） in the southern part of the Nihewan Basin at the northernmost parts of the graben are studied herein. Based on the sedimentary sequences and facies, the sections are divided into three evolutionary stages, such as alluvial fan-eolian red clay, fan delta, and fluvial, with boundaries at -2.8 and -1.8 Ma. Paleocurrent indicators, the composition of coarse clastics, heavy minerals, and the geochemistry of moderate-fine clastics are used to establish the temporal and spatial variations in the source areas. Based on features from the middle- northern basin, we infer that the Nihewan Basin comprises an old NE-SW elongate geotectogene and a young NW-SE elongate subgeotectogene. The main geotectogene in the mid-north is a half-graben bounded by northeast-striking and northwest-dipping normal faults （e.g., Liulengshan Fault）. This group of faults was mainly affected by the Pliocene （before -2.8-2.6 Ma） NW-SE extension and controlled the deposition of sediments. In contrast, the subgeotectogene in the south was affected by northwest-striking normal faults （e.g., Huliuhe Fault） that were controlled by the subsequent weak NE- SW extension in the Pleistocene. The remarkable change in the sedimentary facies and provenance since -1.8 Ma is possibly a signal of either weak or strong NE-SW extension. This result implies that the main tectonic transition ages of -2.8-2.6 Ma and -1.8 Ma in the Weihe-Shanxi Graben are affected by the Tibetan Plateau in Pliocene-Pleistocene.展开更多
This paper presents finite element modeling （FEM） to simulate the present-day stress field and crustal deformation using NE-SW structural section in the central Seismic Gap region of the Garhwal Himalaya. Our study ...This paper presents finite element modeling （FEM） to simulate the present-day stress field and crustal deformation using NE-SW structural section in the central Seismic Gap region of the Garhwal Himalaya. Our study deals with the effect of geometrical characteristics and rock layer parameters on the upper crust. Modeling results show that two types of tectonic regimes developed in the central Seismic Gap region： the geotectonics of the northern part has been controlled by regional compression, whereas southern part is characterized by regional extension. Correspondingly, thrust faults are induced in the northern part and normal faults are extensively developed in the southern front. Those evidences noticeably indicate that the compressive tectonic environment of the Himalaya becomes change into the extensional tectonic regime in its front. The computed shear stress accumulation along the northern fiat of Main Himalayan Thrust （MHT） implies that considerable amount of interseismic stress is building up along the MHT system in the Himalaya, which ultimately release through the possible future great Himalayan earthquake （M 〉 8）. The comparison between our modeled stress field, faulting pattern and horizontal shortening rate with the distribution of the microseismic events, focal mechanism solutions, active faulting and GPS data in the central Seismic Gap region shows good agreement.展开更多
Based on the interpretation of two-dimensional seismic data, this paper analyzes the characteristics of three boundary fault systems including the Shajingzi fault, the Aqia fault and the Tumuxiuke fault around the Awa...Based on the interpretation of two-dimensional seismic data, this paper analyzes the characteristics of three boundary fault systems including the Shajingzi fault, the Aqia fault and the Tumuxiuke fault around the Awati sag of the Tarim Basin, and studies its controlling on hydrocarbon accumulation. Neotectonic movement is ubiquitous in oil and gas bearing basins in China, such as Neogene intense activities of large boundary thrusting faults of the Awati sag: Shajingzi fault, Aqia fault and Tumuxiuke fault. Based on a large number of seismic data, it is showed that they have section wise characteristics in the direction of fault strike, and active periods and associated structures formed of different sections are different. Usually, large anticlinal structures are formed in the upper wall, and faulted anticline controlled by companion faults are formed in the bottom wall. Large faults cut the strata from Cambrian up to Neogene. For the anticline in the upper wall, fault activities caused by neotectonic movement played a destructive role in hydrocarbon accumulation, thus the preservation condition is critical for reservoir formation. In this sense, attention should be paid to formations in the upper walls of Aqia fault and Tumuxiuke fault under the Cambrian salt bed, whose plastic deformation could help to heal faults. Companion faults in the bottom wall cut down to the Cambrian and up to the Triassic serving as the pathway for hydrocarbon migration, and associated structures in the bottom wall are noteworthy exploration targets.展开更多
The distribution characteristics of the oil-water contact are the basis for the reservoir exploration and development and reserves evaluation. The reservoir with a tilted oil-water contact has a unique formation mecha...The distribution characteristics of the oil-water contact are the basis for the reservoir exploration and development and reserves evaluation. The reservoir with a tilted oil-water contact has a unique formation mechanism, and the understanding of its distribution and formation mechanism will directly affect the evaluations for the reservoir type, well deployment, selection of well pattern and type, determination of test section, and reserves evaluation. Based on the analysis of reservoir characteristics, petrophysical properties and geological structure in 40 reservoirs worldwide with tilted oil-water contacts, the progress of the research on the formation mechanisms of titled oil-water contacts is summarized in terms of the hydrodynamic conditions, reservoir heterogeneity, neotectonic movement and oil-gas exploitation. According to the formation mechanism of tilted oil-water contacts and the needs of exploration research, different aspects of research methods are summarized and classified, such as the calculation of equipotential surfaces for oil and water in the formation, analysis of formation pressure and analysis of reservoir physical properties and so on. Based upon statistical analysis, it is suggested that the degree of the inclination of the oil-water contact be divided based on the dip of oil-water contact（DipTOWC）. The tilted oil-water contact is divided into three categories： large dip（DipTOWC≥55 m/km）, medium dip（4 m/km≤DipTOWC55 m/km）, and small dip（DipTOWC4 m/km）. The classification and evaluation method can be combined with structure amplitude and reservoir property. The formation mechanism of domestic and international reservoirs with tilted oil-water contacts are summarized in this paper, which have important significance in guiding the exploration and development of the oilfield with tilted oil-water contacts, reserves evaluation, and well deployment.展开更多
The Quaternary sediments in the Yili Basin can serve as archives for studying the Cenozoic basin-mountain relationship. In this study, based on typical natural sections and boreholes, the surficial sediments of the Hu...The Quaternary sediments in the Yili Basin can serve as archives for studying the Cenozoic basin-mountain relationship. In this study, based on typical natural sections and boreholes, the surficial sediments of the Huocheng area were studied, and their sedimentary ages were obtained using the optically stimulated luminescence(OSL) and electron spin resonance(ESR) dating methods. These dates, combined with changes in the sedimentary facies, provided details of the neotectonic movement in the Yili Basin and adjacent areas. By dating sediments from five sections and three boreholes, we determined that the surficial sediments of the Huocheng area were mainly formed in the Late Pleistocene, with scattered instances of Holocene sediments. The surficial sediments mainly consisted of alluvial fan facies, fluvial facies, lacustrine facies, and desert facies. Based on the activity on the Hongshanzui fault and the northern margin fault of the Wusun Mountains, the Huocheng area was uplifted synchronously with the Tianshan Mountains during the last stage of the Late Pleistocene, causing the desert facies sediments to be superimposed on the former paleo-lake sediments.展开更多
Investigations on stratigraphy, geomorphology and neotectonic movement in the Eastern Kunlun Moun-tains show that there existed a series of ancient lakes, including some saline lakes. in the studied region about30,000...Investigations on stratigraphy, geomorphology and neotectonic movement in the Eastern Kunlun Moun-tains show that there existed a series of ancient lakes, including some saline lakes. in the studied region about30,000 years ago, They were distributed south of the middle Kunlun fault. from the middle-upper reaches of thepresent Narin Gol River in the west to the Alag Lake-Tosou Lake in the east. Of these the ancient Narin GolLake and Kunlun Lake were mainly recharged by the hot water related to valcanos. so the B, Li and K con-tents are relatively high. The neotectonic movement that commenced at 30.000 a B.P. caused the river system in the EasternKunlun Mountains to invade southwards. as a result the ancient lake water was captured to recharge theQarhan area. Therefore, the hot springs related to recent volcanism and faulting on the southern bank of theupper reaches of the Narin Gol River became an important source of saline materials for the Qarhan Lake.展开更多
Boroujerd area has located in the border zone of Zagros mountain and Sanandaj-Sirjan belt in the southwest Iran. Six geomorphic indices were calculated in the study area. Through averaging these indices we obtain inde...Boroujerd area has located in the border zone of Zagros mountain and Sanandaj-Sirjan belt in the southwest Iran. Six geomorphic indices were calculated in the study area. Through averaging these indices we obtain index of active tectonics (Iat). The values of the index were divided into classes to define the degree of active tectonics. Therefore, relative tectonic activity was calculated and their values were classified and analyzed in two groups. Regions were identified as low and moderate levels. In analyzing data and combining them with tectonic setting the results were often associated and justified with regional geology. Our results show that the highest value has located along faulted area, which shows 3 classes of relative tectonic activity (moderate level). Also, other values have located along folded area (low level). Therefore, middle part of study area (sub-basin No. 4) is showing the more active uplifting related to surroundings region (sub-basin No. 1, 2 and 3). In other words, sub-basin No. 4 has got the more active uplifting by quaternary movements of several faults such as Doroud fault.展开更多
Objective The lateral extrusion eastward of the Tibetan Plateau leads to the formation of the Sichuan–Yunnan block, which is the most representative active block in the southeastern margin of the Tibetan Plateau, cha...Objective The lateral extrusion eastward of the Tibetan Plateau leads to the formation of the Sichuan–Yunnan block, which is the most representative active block in the southeastern margin of the Tibetan Plateau, characterized by strong and frequent seismicity(Li Ping et al., 1975; Zhang Peizhen et al., 2003; Li Yong et al., 2017). Its eastern boundary is composed of sinistral faults including the Xianshuihe, Xiaojiang faults, etc., and the western展开更多
High resolution aeromagnetic and seismological data constrained by field-based structural investigations have been used to map and delineate the structural elements that affected and shaped the Midyan area in the nort...High resolution aeromagnetic and seismological data constrained by field-based structural investigations have been used to map and delineate the structural elements that affected and shaped the Midyan area in the northwest part of Saudi Arabia. The area was divided into four major domains defined by NNE, NNW, NW and ENE trending faults identified by trends, patterns and intensity of magnetic anomalies. The ENE trending left-lateral strike-slip faults intersected by NNE trending faults are the predominant tectonic features in the Gulf of Aqaba coastal area and stop at the boundary of a central domain characterized by complexity in the pattern and intensity of magnetic anomalies, that may be attributed to heterogeneity of basement rocks containing complex igneous rock suites including diorite, gabbro, ultramafic and alkali granitic rocks. This domain is characterized by the presence of narrow linear magnetic anomalies that extend for kilometers in an NNW direction, indicating dikes intruded through NNW trending faults. These dikes become WNW-oriented near their northern termination by transfer of movement to WNW-oriented faults marking the northern termination of the Red Sea rift. It is believed that this fault zone is still experiencing neotectonic activity, as evident from recorded seismicity. The aeromagnetic structural resuits coincide with fault plane solutions for the largest earthquakes, confirming aeromagnetic interpreted trends and illustrating mixed mechanisms between extensional and strike-slip faulting. Thus the study area displays different mechanisms associated with different tectonic trends which show clearly in the structural patterns of the area.展开更多
This project studies marine terraces in western Messenia, southwestern Peloponnese, Greece, to propose a model of neotectonic configuration and paleogeographic evolution of western Messenia during the Quaternary. GIS ...This project studies marine terraces in western Messenia, southwestern Peloponnese, Greece, to propose a model of neotectonic configuration and paleogeographic evolution of western Messenia during the Quaternary. GIS analysis of topographic data and geological mapping revealed flanks of raised terraces created on Quaternary marine deposits. Luminescence ages of sediments from the three westernmost marine terraces tend to be consistent OIS-5, OIS-7 and OIS-9, respectively, thus agreeing with the three latest warm stages of the Pleistocene. Moreover, the type and the extent of deformation of the dated marine terraces allowed us to reflect on the neotectonic configuration of western Messenia as well as to conclude that progressive differential uplift over the last 300 ka has induced a dome-like structure to the upper crust of western Messenia.展开更多
The Mottled Zone（MZ） or Hatrurim Formation,which occurs near the Levantine Transform in the South Levant,has been studied during the last 150 years but its origin remains debatable.Mottled Zone Complex/Complexes（MZ...The Mottled Zone（MZ） or Hatrurim Formation,which occurs near the Levantine Transform in the South Levant,has been studied during the last 150 years but its origin remains debatable.Mottled Zone Complex/Complexes（MZC/MZCs） consist of brecciated carbonate and low-temperature calcium-hydro-silicate rocks,which include unusual high- and ultra-high-temperature low-pressure（HT-LP） meta-morphic mineral assemblages.The MZ has been regarded as a product of combustion of bituminous chalks of the Ghareb Fm.of Cretaceous（Maastrichtian） age.In this paper we present detailed geographic, geomorphologic,structural and geological data from the MZCs of the South Levant,which show that the MZCs cannot be stratigraphically correlated with the Ghareb Fm.,because MZC late Oligocene-late Pleistocene deposits occur within or unconformable i.e.,with stratigraphic hiatus,overlap both the late Cretaceous and,in places,Neogene stratigraphic units.We propose an alternative model for the formation of MZCs by tectonically induced mud volcanism during late Oligocene-late Pleistocene time. This model explains（i） the presence of dikes and tube-like bodies,which consist of brecciated exotic clastic material derived from stratigraphically and hypsometrically lower horizons;（ii） mineral assemblages of sanidinite facies metamorphism;（iii） multi-stage character of HT-LP pyrometamorphism;and （iv） multi-stage low-temperature hydrothermal alteration.High temperatures（up to 1500℃） mineral assemblages resulted from combustion of hydrocarbon gases of mud volcanoes.Mud volcanism was spatially and structurally related to neotectonic folds and deformation zones formed in response to opening of the Red Sea rift and propagation of the Levantine Transform Fault.Our model may significantly change the prospects for oil-and-gas deposits in the region.展开更多
Kashaf rud river is located in border zone of East Alborz and Kopet Dagh physiographic provinces in the north east Iran. Geomorphic indices are useful tools to show the neotectonic regimes. These indices have got the ...Kashaf rud river is located in border zone of East Alborz and Kopet Dagh physiographic provinces in the north east Iran. Geomorphic indices are useful tools to show the neotectonic regimes. These indices have got the advantage of being calculated from Arc GIS and remote sensing packages over large area as a useful tool to identify geomorphic anomalies possibly related to active tectonics. In this research, seven geomorphic indices (stream-gradient index, valley floor width-valley height ratio, mountain-front sinuosity, drainage basin asymmetry, hypsometric integral, drainage basin shape and transverse topographic symmetry factor) were calculated along the Kashaf rud river. Then, based on a new index or modified index of active tectonics (Miat) values that calculated by average of seven geomorphic indices, relative tectonic activities levels were revealed. The low class of Miat is mainly in the sub-basins of No. 6, 10, 13, 14, 21, 22, 23, 24 & 28 while the rest of the study area has moderate tectonic activities in the other sub-basins. Our results show that the moderate value has located along faulted area, which shows 2 class of relative tectonic activity. These faults have been formed above an old suture zone between Cimmerian and Eurasian plates.展开更多
Lanzhou Institute of Seismology, China Seismological Bureau, Lanzhou 730000, China 2) Institute of Geology, China Seismological Bureau, Beijing 100029, China
In the past two decades,because of the significant increase in the availability of differential interferometry from synthetic aperture radar and GPS data,spaceborne geodesy has been widely employed to determine the co...In the past two decades,because of the significant increase in the availability of differential interferometry from synthetic aperture radar and GPS data,spaceborne geodesy has been widely employed to determine the co-seismic displacement field of earthquakes.On April 18,2021,a moderate earthquake(Mw 5.8)occurred east of Bandar Ganaveh,southern Iran,followed by intensive seismic activity and aftershocks of various magnitudes.We use two-pass D-InSAR and Small Baseline Inversion techniques via the LiCSBAS suite to study the coseismic displacement and monitor the four-month post-seismic deformation of the Bandar Ganaveh earthquake,as well as constrain the fault geometry of the co-seismic faulting mechanism during the seismic sequence.Analyses show that the co-and postseismic deformation are distributed in relatively shallow depths along with an NW-SE striking and NE dipping complex reverse/thrust fault branches of the Zagros Mountain Front Fault,complying with the main trend of the Zagros structures.The average cumulative displacements were obtained from-137.5 to+113.3 mm/yr in the SW and NE blocks of the Mountain Front Fault,respectively.The received maximum uplift amount is approximately consistent with the overall orogen-normal shortening component of the Arabian-Eurasian convergence in the Zagros region.No surface ruptures were associated with the seismic source;therefore,we propose a shallow blind thrust/reverse fault(depth~10 km)connected to the deeper basal decollement fault within a complex tectonic zone,emphasizing the thin-skinned tectonics.展开更多
基金This project is supported by the NationM Natural Science Foundation of China(No.40238059).
文摘Neotectonism occurred intensively in the Bozhong depression in the Bohai Bay Basin, which was reflected vertically by dramatic subsidence and a number of uplifts and laterally by notable fault movements. This particularity has resulted in the special petroleum geological conditions of the Bozhong depression which are different from those of adjacent lands. For example, the source rocks of the Shahejie Formation were overpressured and hydrocarbon generation occurred in the late stage; the Dongying Formation was deeply buried below the hydrocarbon-generating threshold, therefore there were sufficient oil sources. The rapid subsidence led to starved sedimentation of the Guantao Formation fine sandstone and the regional Minghuazhen Formation lacustrine shale, which formed the Neogene regional reservoir-caprock association. The active faults formed in the neotectonism became passages for oil to migrate from the Paleogene to Neogene. The traps formed by late fault activity and accompanied anticlines provided spaces for the formation of reservoirs. All the above factors match well with one another in the Bozhong depression, providing favorable conditions for the formation of a series of large oilfields in the region
基金supported by Program for Innovative Research Team in the University (Grant No. IRT0658)National Natural Science Foundation of China (Grant No. 90914006)
文摘Late-stage is defined here as the period when Neotectonism occurred since 5.1 Ma. Most petroliferous basins in China lie in the areas where Neotectonism occurred intensively. In recent years, Chinese petroleum geologists have paid much attention to late-stage petroleum accumulation. The PL19-3 giant oilfield is situated where faulting activities occurred violently during Neotectonism. To understand the mechanism of lat-stage rapid accumulation, we discussed the most important aspects responsible for the formation of the giant oilfield, including oil generation, active oil-source rock occurrence, fault activity and fault conduits, late-stage rapid oil injection as well as the distinguishing indicators. This study shows that: (1) sufficient oil was supplied to the PL19-3 field since 5.1 Ma because the PL19-3 structure was surrounded by four sags in which three intervals of high-quality source rocks remained active during Neotectonism; (2) densely distributed faults and high porosity/permeability sandstone carrier beds comprised the effective conduit system for oil migration and injection; (3) oil migrated along the faults and charged the PL19-3 structure rapidly by means of seismic pumping which was triggered by frequent earthquakes during Neotetonism. It is documented that elevated reservoir temperature, abnormal geothermal gradients and abnormally high homogenization temperatures of the fluid inclusions are the indicators for late-stage rapid oil accumulation.
基金UGC,Minor Research Project,Govt. Of India(F.PSW-032/08-09_ERO) for financial supportfinancial help from DST(ESS/16/243/2006-EMR-ll)
文摘This paper aims to unveit neotectonic imprints in topography, drainage and sediments in the 46.25 km tong course of the River Chet from its source down to its attuvial fan at the base of the Himatayan Mountain Front in the Darjeeting-Jatpaiguri districts of India. A semi-circutar ridge detimits its primary catchment. Within confinement of this watershed basin the drainage pattern is composite being convergent atong the periphery and divergent on a butte inside. AtE these geomorphic neotectonic imprints are accom- panied by ramp and fiat structures and spectacutar mytonitization of rocks. High hypsometric index and convex shape of the hypsometric curve derived from the centrat near-straight course of the river between the primary catchment and the Main Frontat Thrust （MFT） atso reftects tectonic youthfutness of the river course. It is wett manifested atso in widety variabte stream index and stream gradient index ratios （SL/K） often exceeding 2. In response to neotectonism, this river course as a whore shifted westward between 1962 and 2007. Maximum reduction of the stream gradient on top of the MFT is etoquent enough about recent uptift of the thrust ridge. The high average stope gradient of canyon watt about 45.68° is wett consistent with this uptift. Very tow channet-width/vaUey-height ratio along the river further corroborates the uptift. The attuviat fan system of the River Chet is comprised of five morphogenetic fans stacked one above another with a tendency to shrink and shift progressively upstope. They differ from each other in terms of titt, axiat orientation, primary depositionat surface gradient and convexity in transverse section and thus present a writ of ongoing tectonism. Progressive upward increase in the share of distat crystattine rocks in ctast composition within attuviat fan package is a dear proxy for southerty advancement of the MFT. Concomitant increase in maximum ctast size is in good agreement with sediment source uptift. Art the five fans are, however, dormant now. Present-day River Chet deeply incises through ate of them and suggests further basement uplift in the context of frequent evidences of neotectonism att around, atthough the rote of climate remains uncertain in absence of adequate data.
文摘This research investigates dynamic earth processes within the South Setifian allochthonous ensemble,providing insights into landscape evolution and seismotectonic activity within the Tellian mountain chain.Focusing on the Jebel Gustar and Kef Lahmar area,which includes 14 sub-basins,this research uses a DEM-based technique to assess Holocene activities,lineament characteristics,and stream systems.Five geomorphic indices are used to assess relative active tectonics:the stream lengthgradient index(SL),drainage basin asymmetry(AF),valley-floor width to valley height ratio(VF),drainage basin shape(BS),and mountain front sinuosity(SMF).A weighted overlay of these five indices produces the Index of Relative Active Tectonics(IRAT)map.The findings reveal significant neotectonic activity in the study area,supported by profound basement faulting.This research highlights the morpho-structural processes and neotectonics activity in the Jebel Gustar,providing a framework for investigating the evolution of this structure.Additionally,it enhances comprehension of the interactions between the alpine range's internal zones in Eastern Algeria and the Atlasic domain.This study proposes a systematic approach to evaluate the tectonic and geomorphological dynamics of the South Setif region.
基金supported by NASA to Abduwasit Ghulam and Timothy M Kusky (No. 08-182)the National Natural Science Foundation of China (No. 40821061)Ministry of Education of China (No. B07039)
文摘Field analysis and differential interferometry derived from Synthetic Aperture Radar （PALSAR） of the epicentral area of the May 12 2008 Mw 8.0 Wenchuan （汶川） earthquake zone reveal details about fault ruptures and ground displacements, with field-documented vertical offsets reaching 12 m along the trace of the main fault rupture, and PALSAR-measured horizontal displacements reaching 12.3 m. We document slip indicators on the fault scarp that show initially sub-horizontal then progressively steeper slip increments with time along the same fault during the 2 min earthquake, suggesting that the rupture propagated as a mixed Mode Ⅱ-Ⅲ fracture, with strike-slip movement at the tip directing energy from the initial rupture to points north of the epicenter, followed by vertical displacement in the interior of the slipped region. Field, seismic, and PALSAR-measured displacements are dominantly thrust near the epicentral region, and dextral in northeasterly areas, showing that slipwas partitioned along the fault in space and time during the earthquake. The changing slip directions may correlate with three main pulses of energy release at 0, 23, and 57 s during the earthquake as recorded by seismograms. The earthquake generated massive landsfides 〉100 km north of the epicenter along the trace of the fault. These massive sturzstroms formed where entire mountainsides collapsed and moved at high velocity down populated mountain valleys, jumping smaller mountains and ricocheting off steep canyon walls. These avalanches rode on cushions of water and compressed air that generated air blasts from beneath the debris, knocking down trees high on opposing mountain slopes. The concentration of massive landslides and ground deformation so far north of the epicenter was related to the Mode Ⅱ-Ⅲ fracture propagation focusing seismic energy along the fault towards the north, explaining why so much devastation occurred 〉100 km from the epicenter, such as in the destroyed city of Beichuan （北川）. Understanding near-surface earthquake processes and geological hazards associated with massive earthquakes in populated mountainous areas has the potential to save many lives in the future.
基金supported by the Foundation Project of State Key Laboratory of Petroleum Resources and Prospecting (PRPDX2008-05)the "973" National Key Basic Research Program (2006CB202308)
文摘Neotectonic movement refers to the tectonic movement that has happened since the Cenozoic, which is the latest movement. It has the most important influence on the basins in west China, especially on the hydrocarbon accumulation in the western foreland basins. We determined the time of neotectonic movement in the Kuqa Foreland Basin, which began from the Neogene, and analyzed the patterns of movement, which were continuous and fast subsidence in the vertical direction and intense lateral compression. The structure styles are that the faulting is weakened and the folding is strengthened gradually from north to south. We studied the control of neotectonic movement on the hydrocarbon accumulation process and model in the Kuqa Foreland Basin with basin simulation technique. The largest subsidence rate of the Kuqa Foreland Basin reached 1,200 m/Ma during the neotectonic movement, leading to rapid maturing of source rock within 5 Ma and a large quantity of hydrocarbon being generated and expelled. The thick neotectonic strata can form high quality reservoirs with the proved gas and oil reserves accounting for 5% and 27% of the total reserves, respectively. 86% of the structural traps were formed in the neotectonic movement period. The faults formed during the neotectonic movement serve as important migration pathways and they exist in the region where the hydrocarbon reservoirs are distributed. Abnormally high pressure caused by the intense lateral compression, thick neotectonic strata deposition and rapid hydrocarbon generation provide driving force for hydrocarbon migration. The accumulation elements match each other well over a short period, leading to many large gas fields formed later in the Kuqa Foreland Basin.
基金supported by Grants from National Natural Science Foundation of China(No.41172150)the Ministry of Land and Resources of China(No.201211005–1)+1 种基金China Geological Survey(CGS)(No.1212011120099)China Scholarship Council(CSC)
文摘The Late Cenozoic basins in the Weihe-Shanxi Graben, North China Craton are delineated by northeast-striking faults. The faults have, since a long time, been related to the progressive uplift and northeastward expansion of the Tibetan Plateau. To show the relation between the basins and faults, two Pliocene-Pleistocene stratigraphic sections （Chengqiang and Hongyanangou） in the southern part of the Nihewan Basin at the northernmost parts of the graben are studied herein. Based on the sedimentary sequences and facies, the sections are divided into three evolutionary stages, such as alluvial fan-eolian red clay, fan delta, and fluvial, with boundaries at -2.8 and -1.8 Ma. Paleocurrent indicators, the composition of coarse clastics, heavy minerals, and the geochemistry of moderate-fine clastics are used to establish the temporal and spatial variations in the source areas. Based on features from the middle- northern basin, we infer that the Nihewan Basin comprises an old NE-SW elongate geotectogene and a young NW-SE elongate subgeotectogene. The main geotectogene in the mid-north is a half-graben bounded by northeast-striking and northwest-dipping normal faults （e.g., Liulengshan Fault）. This group of faults was mainly affected by the Pliocene （before -2.8-2.6 Ma） NW-SE extension and controlled the deposition of sediments. In contrast, the subgeotectogene in the south was affected by northwest-striking normal faults （e.g., Huliuhe Fault） that were controlled by the subsequent weak NE- SW extension in the Pleistocene. The remarkable change in the sedimentary facies and provenance since -1.8 Ma is possibly a signal of either weak or strong NE-SW extension. This result implies that the main tectonic transition ages of -2.8-2.6 Ma and -1.8 Ma in the Weihe-Shanxi Graben are affected by the Tibetan Plateau in Pliocene-Pleistocene.
文摘This paper presents finite element modeling （FEM） to simulate the present-day stress field and crustal deformation using NE-SW structural section in the central Seismic Gap region of the Garhwal Himalaya. Our study deals with the effect of geometrical characteristics and rock layer parameters on the upper crust. Modeling results show that two types of tectonic regimes developed in the central Seismic Gap region： the geotectonics of the northern part has been controlled by regional compression, whereas southern part is characterized by regional extension. Correspondingly, thrust faults are induced in the northern part and normal faults are extensively developed in the southern front. Those evidences noticeably indicate that the compressive tectonic environment of the Himalaya becomes change into the extensional tectonic regime in its front. The computed shear stress accumulation along the northern fiat of Main Himalayan Thrust （MHT） implies that considerable amount of interseismic stress is building up along the MHT system in the Himalaya, which ultimately release through the possible future great Himalayan earthquake （M 〉 8）. The comparison between our modeled stress field, faulting pattern and horizontal shortening rate with the distribution of the microseismic events, focal mechanism solutions, active faulting and GPS data in the central Seismic Gap region shows good agreement.
基金financially supported by China Geological Survey Project (12120115001801,1211302108022,DD20160169 and DD20190708)the National Natural Science Foundation of China (41072102).
文摘Based on the interpretation of two-dimensional seismic data, this paper analyzes the characteristics of three boundary fault systems including the Shajingzi fault, the Aqia fault and the Tumuxiuke fault around the Awati sag of the Tarim Basin, and studies its controlling on hydrocarbon accumulation. Neotectonic movement is ubiquitous in oil and gas bearing basins in China, such as Neogene intense activities of large boundary thrusting faults of the Awati sag: Shajingzi fault, Aqia fault and Tumuxiuke fault. Based on a large number of seismic data, it is showed that they have section wise characteristics in the direction of fault strike, and active periods and associated structures formed of different sections are different. Usually, large anticlinal structures are formed in the upper wall, and faulted anticline controlled by companion faults are formed in the bottom wall. Large faults cut the strata from Cambrian up to Neogene. For the anticline in the upper wall, fault activities caused by neotectonic movement played a destructive role in hydrocarbon accumulation, thus the preservation condition is critical for reservoir formation. In this sense, attention should be paid to formations in the upper walls of Aqia fault and Tumuxiuke fault under the Cambrian salt bed, whose plastic deformation could help to heal faults. Companion faults in the bottom wall cut down to the Cambrian and up to the Triassic serving as the pathway for hydrocarbon migration, and associated structures in the bottom wall are noteworthy exploration targets.
文摘The distribution characteristics of the oil-water contact are the basis for the reservoir exploration and development and reserves evaluation. The reservoir with a tilted oil-water contact has a unique formation mechanism, and the understanding of its distribution and formation mechanism will directly affect the evaluations for the reservoir type, well deployment, selection of well pattern and type, determination of test section, and reserves evaluation. Based on the analysis of reservoir characteristics, petrophysical properties and geological structure in 40 reservoirs worldwide with tilted oil-water contacts, the progress of the research on the formation mechanisms of titled oil-water contacts is summarized in terms of the hydrodynamic conditions, reservoir heterogeneity, neotectonic movement and oil-gas exploitation. According to the formation mechanism of tilted oil-water contacts and the needs of exploration research, different aspects of research methods are summarized and classified, such as the calculation of equipotential surfaces for oil and water in the formation, analysis of formation pressure and analysis of reservoir physical properties and so on. Based upon statistical analysis, it is suggested that the degree of the inclination of the oil-water contact be divided based on the dip of oil-water contact（DipTOWC）. The tilted oil-water contact is divided into three categories： large dip（DipTOWC≥55 m/km）, medium dip（4 m/km≤DipTOWC55 m/km）, and small dip（DipTOWC4 m/km）. The classification and evaluation method can be combined with structure amplitude and reservoir property. The formation mechanism of domestic and international reservoirs with tilted oil-water contacts are summarized in this paper, which have important significance in guiding the exploration and development of the oilfield with tilted oil-water contacts, reserves evaluation, and well deployment.
基金financial support of the Natural Science Foundation of China (No. 41772200)China Earthquake Administration teacher research Fund (No. 20140103)+1 种基金China Geological Survey Program (No. 121201011000150021, No.DD20190351)Innovation Leading Talents Program of Qingdao (19–3–2–19–zhc)
文摘The Quaternary sediments in the Yili Basin can serve as archives for studying the Cenozoic basin-mountain relationship. In this study, based on typical natural sections and boreholes, the surficial sediments of the Huocheng area were studied, and their sedimentary ages were obtained using the optically stimulated luminescence(OSL) and electron spin resonance(ESR) dating methods. These dates, combined with changes in the sedimentary facies, provided details of the neotectonic movement in the Yili Basin and adjacent areas. By dating sediments from five sections and three boreholes, we determined that the surficial sediments of the Huocheng area were mainly formed in the Late Pleistocene, with scattered instances of Holocene sediments. The surficial sediments mainly consisted of alluvial fan facies, fluvial facies, lacustrine facies, and desert facies. Based on the activity on the Hongshanzui fault and the northern margin fault of the Wusun Mountains, the Huocheng area was uplifted synchronously with the Tianshan Mountains during the last stage of the Late Pleistocene, causing the desert facies sediments to be superimposed on the former paleo-lake sediments.
文摘Investigations on stratigraphy, geomorphology and neotectonic movement in the Eastern Kunlun Moun-tains show that there existed a series of ancient lakes, including some saline lakes. in the studied region about30,000 years ago, They were distributed south of the middle Kunlun fault. from the middle-upper reaches of thepresent Narin Gol River in the west to the Alag Lake-Tosou Lake in the east. Of these the ancient Narin GolLake and Kunlun Lake were mainly recharged by the hot water related to valcanos. so the B, Li and K con-tents are relatively high. The neotectonic movement that commenced at 30.000 a B.P. caused the river system in the EasternKunlun Mountains to invade southwards. as a result the ancient lake water was captured to recharge theQarhan area. Therefore, the hot springs related to recent volcanism and faulting on the southern bank of theupper reaches of the Narin Gol River became an important source of saline materials for the Qarhan Lake.
文摘Boroujerd area has located in the border zone of Zagros mountain and Sanandaj-Sirjan belt in the southwest Iran. Six geomorphic indices were calculated in the study area. Through averaging these indices we obtain index of active tectonics (Iat). The values of the index were divided into classes to define the degree of active tectonics. Therefore, relative tectonic activity was calculated and their values were classified and analyzed in two groups. Regions were identified as low and moderate levels. In analyzing data and combining them with tectonic setting the results were often associated and justified with regional geology. Our results show that the highest value has located along faulted area, which shows 3 classes of relative tectonic activity (moderate level). Also, other values have located along folded area (low level). Therefore, middle part of study area (sub-basin No. 4) is showing the more active uplifting related to surroundings region (sub-basin No. 1, 2 and 3). In other words, sub-basin No. 4 has got the more active uplifting by quaternary movements of several faults such as Doroud fault.
基金supported by the National Science Foundation of China (grant No. 41472204)
文摘Objective The lateral extrusion eastward of the Tibetan Plateau leads to the formation of the Sichuan–Yunnan block, which is the most representative active block in the southeastern margin of the Tibetan Plateau, characterized by strong and frequent seismicity(Li Ping et al., 1975; Zhang Peizhen et al., 2003; Li Yong et al., 2017). Its eastern boundary is composed of sinistral faults including the Xianshuihe, Xiaojiang faults, etc., and the western
基金the Deanship of Scientific Research at King Saud University for funding this research group (No.RG-1436-011)
文摘High resolution aeromagnetic and seismological data constrained by field-based structural investigations have been used to map and delineate the structural elements that affected and shaped the Midyan area in the northwest part of Saudi Arabia. The area was divided into four major domains defined by NNE, NNW, NW and ENE trending faults identified by trends, patterns and intensity of magnetic anomalies. The ENE trending left-lateral strike-slip faults intersected by NNE trending faults are the predominant tectonic features in the Gulf of Aqaba coastal area and stop at the boundary of a central domain characterized by complexity in the pattern and intensity of magnetic anomalies, that may be attributed to heterogeneity of basement rocks containing complex igneous rock suites including diorite, gabbro, ultramafic and alkali granitic rocks. This domain is characterized by the presence of narrow linear magnetic anomalies that extend for kilometers in an NNW direction, indicating dikes intruded through NNW trending faults. These dikes become WNW-oriented near their northern termination by transfer of movement to WNW-oriented faults marking the northern termination of the Red Sea rift. It is believed that this fault zone is still experiencing neotectonic activity, as evident from recorded seismicity. The aeromagnetic structural resuits coincide with fault plane solutions for the largest earthquakes, confirming aeromagnetic interpreted trends and illustrating mixed mechanisms between extensional and strike-slip faulting. Thus the study area displays different mechanisms associated with different tectonic trends which show clearly in the structural patterns of the area.
基金supported by the State Scholarships Foundation of Greece(No.1500521537.008.040)
文摘This project studies marine terraces in western Messenia, southwestern Peloponnese, Greece, to propose a model of neotectonic configuration and paleogeographic evolution of western Messenia during the Quaternary. GIS analysis of topographic data and geological mapping revealed flanks of raised terraces created on Quaternary marine deposits. Luminescence ages of sediments from the three westernmost marine terraces tend to be consistent OIS-5, OIS-7 and OIS-9, respectively, thus agreeing with the three latest warm stages of the Pleistocene. Moreover, the type and the extent of deformation of the dated marine terraces allowed us to reflect on the neotectonic configuration of western Messenia as well as to conclude that progressive differential uplift over the last 300 ka has induced a dome-like structure to the upper crust of western Messenia.
基金Dr.Ella Sokol is acknowledged for joint collaboration while studying metamorphic mineralogy of MSCz.Contribution to IGCP Project #592 sponsored by UNESCOIUGSIn memory of Prof.R.Shagam (Beer-Sheva University),recently passed away,who encouraged our model and supported our researchfulfilled in the frame of Science project of Institute of Geology and Mineralogy,Siberian Branch,Russian Academy of Sciences
文摘The Mottled Zone（MZ） or Hatrurim Formation,which occurs near the Levantine Transform in the South Levant,has been studied during the last 150 years but its origin remains debatable.Mottled Zone Complex/Complexes（MZC/MZCs） consist of brecciated carbonate and low-temperature calcium-hydro-silicate rocks,which include unusual high- and ultra-high-temperature low-pressure（HT-LP） meta-morphic mineral assemblages.The MZ has been regarded as a product of combustion of bituminous chalks of the Ghareb Fm.of Cretaceous（Maastrichtian） age.In this paper we present detailed geographic, geomorphologic,structural and geological data from the MZCs of the South Levant,which show that the MZCs cannot be stratigraphically correlated with the Ghareb Fm.,because MZC late Oligocene-late Pleistocene deposits occur within or unconformable i.e.,with stratigraphic hiatus,overlap both the late Cretaceous and,in places,Neogene stratigraphic units.We propose an alternative model for the formation of MZCs by tectonically induced mud volcanism during late Oligocene-late Pleistocene time. This model explains（i） the presence of dikes and tube-like bodies,which consist of brecciated exotic clastic material derived from stratigraphically and hypsometrically lower horizons;（ii） mineral assemblages of sanidinite facies metamorphism;（iii） multi-stage character of HT-LP pyrometamorphism;and （iv） multi-stage low-temperature hydrothermal alteration.High temperatures（up to 1500℃） mineral assemblages resulted from combustion of hydrocarbon gases of mud volcanoes.Mud volcanism was spatially and structurally related to neotectonic folds and deformation zones formed in response to opening of the Red Sea rift and propagation of the Levantine Transform Fault.Our model may significantly change the prospects for oil-and-gas deposits in the region.
文摘Kashaf rud river is located in border zone of East Alborz and Kopet Dagh physiographic provinces in the north east Iran. Geomorphic indices are useful tools to show the neotectonic regimes. These indices have got the advantage of being calculated from Arc GIS and remote sensing packages over large area as a useful tool to identify geomorphic anomalies possibly related to active tectonics. In this research, seven geomorphic indices (stream-gradient index, valley floor width-valley height ratio, mountain-front sinuosity, drainage basin asymmetry, hypsometric integral, drainage basin shape and transverse topographic symmetry factor) were calculated along the Kashaf rud river. Then, based on a new index or modified index of active tectonics (Miat) values that calculated by average of seven geomorphic indices, relative tectonic activities levels were revealed. The low class of Miat is mainly in the sub-basins of No. 6, 10, 13, 14, 21, 22, 23, 24 & 28 while the rest of the study area has moderate tectonic activities in the other sub-basins. Our results show that the moderate value has located along faulted area, which shows 2 class of relative tectonic activity. These faults have been formed above an old suture zone between Cimmerian and Eurasian plates.
基金State Key Basic Research Development and Programming Project (G19980407-04) and the Project during the ninth Five-Year Plan of Gansu Province (GK973-2-110A).
文摘Lanzhou Institute of Seismology, China Seismological Bureau, Lanzhou 730000, China 2) Institute of Geology, China Seismological Bureau, Beijing 100029, China
文摘In the past two decades,because of the significant increase in the availability of differential interferometry from synthetic aperture radar and GPS data,spaceborne geodesy has been widely employed to determine the co-seismic displacement field of earthquakes.On April 18,2021,a moderate earthquake(Mw 5.8)occurred east of Bandar Ganaveh,southern Iran,followed by intensive seismic activity and aftershocks of various magnitudes.We use two-pass D-InSAR and Small Baseline Inversion techniques via the LiCSBAS suite to study the coseismic displacement and monitor the four-month post-seismic deformation of the Bandar Ganaveh earthquake,as well as constrain the fault geometry of the co-seismic faulting mechanism during the seismic sequence.Analyses show that the co-and postseismic deformation are distributed in relatively shallow depths along with an NW-SE striking and NE dipping complex reverse/thrust fault branches of the Zagros Mountain Front Fault,complying with the main trend of the Zagros structures.The average cumulative displacements were obtained from-137.5 to+113.3 mm/yr in the SW and NE blocks of the Mountain Front Fault,respectively.The received maximum uplift amount is approximately consistent with the overall orogen-normal shortening component of the Arabian-Eurasian convergence in the Zagros region.No surface ruptures were associated with the seismic source;therefore,we propose a shallow blind thrust/reverse fault(depth~10 km)connected to the deeper basal decollement fault within a complex tectonic zone,emphasizing the thin-skinned tectonics.
