To assist the analysis of tsunami hazards for Qatar coastal areas were using numerical model. By Tsunamis waves created from submarine earthquakes of magnitude of (M<sub>w</sub>) 8.6 and 9.0 in Richard sca...To assist the analysis of tsunami hazards for Qatar coastal areas were using numerical model. By Tsunamis waves created from submarine earthquakes of magnitude of (M<sub>w</sub>) 8.6 and 9.0 in Richard scale along the Makran Subduction Zone (MSZ) as well as coastal landslides with soil volume of 1.25 to 2.0 km<sup>3</sup> along Iranian coast inside the Arabian Gulf is considered. TUNAMI-N2KISR model (Al-Salem) was applied in this study to predict the tsunami propagation and magnitude of Tsunami induced wave heights. The model adopts to solve shallow water equations describing nonlinear long-wave theory. The model also incorporate tidal effect inside the Arabian Gulf as a tsunami travel time from Makran Subduction to Qatar coastline takes more than 9 hours with the tidal range of about 1.6 m during Spring Tide event. For coastal landslides, tsunami generation was simulated using a two-layer numerical model, developed by solving nonlinear long-wave equations. Two-layer model was used to determine initial wave deformation generated by a landslide case. Then TUNAMI-N2KISR was use to simulate tsunami wave propagation. Tsunami waves from landslide scenario arrived after 2.5 - 3 hr with maximum tsunami amplitudes along coasts of Ras laffan-Qatar were 0.8 to 1.0 m. Incorporation of ocean tide is found to impose some small effect on tsunami amplitude at Qatar coastline and nearby areas for the Mw 9.0 earthquake due to small tidal range in this area. In addition, it is found that the tsunami arrival time has become shorter.展开更多
The Makran accretionary wedge has the smallest subduction angle among any accretionary prism in the world. The factors controlling the spacing and morphological development of its deep thrust faults, as well as the fo...The Makran accretionary wedge has the smallest subduction angle among any accretionary prism in the world. The factors controlling the spacing and morphological development of its deep thrust faults, as well as the formation mechanism of shallow normal faults, remain unclear. Meanwhile, the factors affecting the continuity of plane faults must be comprehensively discussed. Clarifying the development characteristics and deformation mechanisms of the Makran accretionary wedge is crucial to effectively guide the exploration of gas hydrate deposits in the area. This study aims to interpret seismic data to identify typical structures in the Makran accretionary wedge, including deep imbricate thrust faults, shallow and small normal faults, wedge-shaped piggyback basins, mud diapirs with fuzzy and disorderly characteristics of reflection, décollements with a northward tilt of 1° – 2°, and large seamounts. Physical simulation-based experiments are performed to comprehensively analyze the results of the plane, section, and slices of the wedge. Results reveal that the distances between and shapes of thrust faults in the deep parts of the Makran accretionary wedge are controlled by the bottom décollement. The uplift of the thrust fault-related folds and the upwelling of the mud diapirs primarily contribute to the formation of small normal faults in the shallow part of the area. The mud diapirs originate from plastic material at the bottom, while those that have developed in the area near the trench are larger. Seamounts and mud diapirs break the continuity of fault plane distribution.展开更多
The Durkan Complex is a tectonic element of the Makran Accretionary Prism(SE Iran)that includes fragments of Late Cretaceous seamounts.In this paper,the results of map-to micro-scale structural studies of the western ...The Durkan Complex is a tectonic element of the Makran Accretionary Prism(SE Iran)that includes fragments of Late Cretaceous seamounts.In this paper,the results of map-to micro-scale structural studies of the western Durkan Complex are presented with the aim to describe its structural and tectonometamorphic evolution.The Durkan Complex consists of several tectonic units bordered by mainly NNW-striking thrusts.Three main deformation phases(D_(1),D_(2),and D_(3))are distinguished and likely occurred from the Late Cretaceous to the Miocene–Pliocene.D_(1) is characterized by sub-isoclinal to close and W-verging folds associated with an axial plane foliation and shear zone along the fold limbs.This phase records the accretion of fragments of the seamount within the Makran at blueschist facies metamorphic conditions(160–300℃ and 0.6–1.2 GPa).D_(2) is characterized by open to close folds with subhorizontal axial plane that likely developed during the exhumation of previously accreted seamount fragments.An upper Paleocene–Eocene siliciclastic succession unconformably sealed the D_(1) and D_(2) structures and is,in turn,deformed by W-verging thrust faults typical of D_(3).The latter likely testifies for a Miocene–Pliocene tectonic reworking of the accreted seamount fragments with the activation of out of sequence thrusts.Our results shed light on the mechanism of accretion of seamount materials in the accretionary prisms,suggesting that seamount slope successions favour the localization and propagation of the basal décollement.This study further confirms that the physiography of the subducting plates plays a significant role in the tectonic evolution of the subduction complexes.展开更多
The Tortonian–Calabrian strata of Offshore Makran(Pakistan)is investigated for the purpose of reservoir assessment.The stratigraphy and petrophysics indicate that the Neogene sediments have tight reservoir potential ...The Tortonian–Calabrian strata of Offshore Makran(Pakistan)is investigated for the purpose of reservoir assessment.The stratigraphy and petrophysics indicate that the Neogene sediments have tight reservoir potential with porosities in the range of 3%–9%and 40%–50%water saturation.The mineralogical cross plots indicate a mixed lithology with an abundance of dolomite and calcite,together with minor quartz content and shale.The seismic interpretation demonstrates medium–high amplitude reflection patterns,mud diapirs coupled with onlapping strata and the occurrence of bottom simulating reflectors(BSRs).The BSRs are characterized by diminished amplitude,low continuity and exhibiting acoustic blanking zones.The high formation pressure results indicate overpressure zones,suggesting the occurrence of overpressured shales in the Jal Pari-1A.The presence of mud diapirs and gas chimneys are the result of tectonic forces acting at the junction of the Arabian,Indian and Eurasian plates,whereas,BSRs prove the existence of gas charged sediments supporting the formation of mud diapirism in the region.It is concluded that the high rates of sedimentation during the Neogene are likely to have contributed to the development of the high formation pressure.Revised mud weights,casing policies,pore pressure transients and geophysical inversion studies will help alleviate drilling risks in future exploration strategies.展开更多
Seabed fluid escape is active in the Makran subduction zone,Arabian Sea.Based on the new highresolution 2D seismic data,acoustic blanking zones and seafloor mounds are identified.Acoustic blanking zones include three ...Seabed fluid escape is active in the Makran subduction zone,Arabian Sea.Based on the new highresolution 2D seismic data,acoustic blanking zones and seafloor mounds are identified.Acoustic blanking zones include three kinds of geometries:Bell-shaped,vertically columnar and tilted zones.The bellshaped blanking zone is characterized by weak and discontinuous reflections in the interior and upbending reflections on the top,interpreted as gas chimneys.Vertically columnar blanking zone is interpreted as side-imaged gas chimneys associated with focused fluid flow and topped by a seafloor anomaly expressed as a localized reflection discontinuity,which may together serve as a vent structure.Tilted acoustic blanking zone could be induced by accretionary thrust activity and rapid sedimentation surrounding slope.Seafloor mounds occur at the sites of bell-shaped acoustic blanking zone and may be associated with the material intrusion.Bottom simulating refectors(BSRs)are widely distributed and exhibit a series of characteristics including diminished amplitude,low continuity as well as local shoaling overlapping with these acoustic blanking zones.The large amount of gases dissociated from the gas hydrates migrated upwards and then arrived at the near-seafloor sediments,followed by the formation of the gas hydrates and hence the seafloor mound.展开更多
The Makran accretionary prism is located at the junction of the Eurasian Plate,Arabian Plate and Indian Plate and is rich in natural gas hydrate(NGH)resources.It consists of a narrow continental shelf,a broad continen...The Makran accretionary prism is located at the junction of the Eurasian Plate,Arabian Plate and Indian Plate and is rich in natural gas hydrate(NGH)resources.It consists of a narrow continental shelf,a broad continental slope,and a deformation front.The continental slope can be further divided into the upper slope,middle slope,and lower slope.There are three types of diapir structure in the accretionary prism,namely mud diapir,mud volcano,and gas chimney.(1)The mud diapirs can be grouped into two types,namely the ones with low arching amplitude and weak-medium activity energy and the ones with high arching amplitude and medium-strong activity energy.The mud diapirs increase from offshore areas towards onshore areas in general,while the ones favorable for the formation of NGH are mainly distributed on the middle slope in the central and western parts of the accretionary prism.(2)The mud volcanoes are mainly concentrated along the anticline ridges in the southern part of the lower slope and the deformation front.(3)The gas chimneys can be grouped into three types,which are located in piggyback basins,active anticline ridges,and inactive anticline ridges,respectively.They are mainly distributed on the middle slope in the central and western parts of the accretionary prism and most of them are accompanied with thrust faults.The gas chimneys located at different tectonic locations started to be active at different time and pierced different horizons.The mud diapirs,mud volcanoes,and gas chimneys and thrust faults serve as the main pathways of gas migration,and thus are the important factors that control the formation,accumulation,and distribution of NGH in the Makran accretionary prism.Mud diapir/gas chimney type hydrate develop in the middle slope,mud volcano type hydrate develop in the southern lower slope and the deformation front,and stepped accretionary prism type hydrate develop on the central and northern lower slope.The middle slope,lower slope and deformation front in the central and western parts of the Mak展开更多
The Napag is the biggest Mud Volcano at Makran in Iran. The main aim of this research is the investigation of geologic setting and geographic situation of Napag Mud Volcano as a well-known mud diapir at Makran on the ...The Napag is the biggest Mud Volcano at Makran in Iran. The main aim of this research is the investigation of geologic setting and geographic situation of Napag Mud Volcano as a well-known mud diapir at Makran on the south eastern margin of Iran. The Napag Mud Volcano has been formed during quaternary of as a conical hill on the flat plain in coastal region Oman Sea. There are badlands area and several mud volcanoes that they have been triggered by longitudinal normal faults. This normal faults have been developed in neotectonic regime by the roll-back of oceanic lithosphere (beneath of Oman Sea). Finally, the main characteristics of the Napag mud diapir are presented.展开更多
Makran zone is one of the largest accretionary wedges in the world. This research had used methods such as studies of Office and library, field observation and surveying that several field visits, sampling, registered...Makran zone is one of the largest accretionary wedges in the world. This research had used methods such as studies of Office and library, field observation and surveying that several field visits, sampling, registered structural evidence, Laboratory studies, Data analysis, interpretation and conclusions. The most important objective of this study is assessment of Tectonics and hazard Potential in Coasts the Oman Sea based on tectonics and sedimentology. The northward movement and subduction of Oman oceanic lithosphere beneath Iranian micro-plate at a very shallow angle and at high rate is responsible for active orogenesis and uplift. Detailed seismological and geological information in planning is extremely essential to avoid any disaster. It is to be remembered that seismicity does not remain fixed in an area but migrates slowly with time. Thus, the planners are expected to be more concerned with the building code and prevention strategies. It is also important to mention that the Coastal zones are always vulnerable to natural hazards and liquefaction. The geomorphology of an area is the first indicator of on-going tectonic activity. In order to measure the amount of deformation due to tectonic processes, the initial geometry of the geomorphic markers is reconstructed accurately. Study of sediments shows that abundant shell fragments organized in laminae also favor a storm origin. Storm deposits contain no internal mud layers and rarely contain pieces of mud. Maximum deposit thickness is near the shore, and landward thinning of the deposit is commonly abrupt. Storm deposits fill in topographic lows, and the upper surface is relatively uniform in elevation alongshore. Finally, landforms of tectonically active regions and sediments are controlling factors interactions between tectonic, sedimentary, climatic, and surficial processes.展开更多
In this paper, remote sensing techniques,as well as field studies, have been used to investigate the geomorphological processes and landscape evolution along the Saravan Fault, SE Iran to highlight how topographic fea...In this paper, remote sensing techniques,as well as field studies, have been used to investigate the geomorphological processes and landscape evolution along the Saravan Fault, SE Iran to highlight how topographic features were influenced by active tectonics. Quantitative geomorphic analysis was carried out using mountain-front sinuosity(Smf),valley floor width-valley height ratio(Vf), drainage basin asymmetry factor(Af), Hypsometric integral(Hi), drainage basin shape index(Bs), mean axial slope of channel(MASC), standard deviation of topography(STD) and index of active tectonic(Iat).Remote sensing techniques, as well as field studies revealed that the Saravan Fault have three parts trending N-S, NW-SE, and E-W. Obtained results show that basins with high Iat index are located at where the strike of the Saravan Faults changes and where several strike-slip faults are crossed the Saravan fault.展开更多
The major seismicity source in the northern Arabian Sea is the Makran Subduction Zone (MSZ) that defines the tectonic boundary between the Arabian plate and the Eurasian plate, located offshore Iran and Pakistan over ...The major seismicity source in the northern Arabian Sea is the Makran Subduction Zone (MSZ) that defines the tectonic boundary between the Arabian plate and the Eurasian plate, located offshore Iran and Pakistan over which an instrumentally registered earthquake (Mw 8.1) generated a tsunami on 27 November, 1945. It has caused severe cataclysm to a vulnerable population along the surrounding coastlines, including India. It has been on a long seismic quiescence since this last event. The population and industrialization have exponentially increased along the coastal areas in last half decade. The highly exposed coastal locations to the tsunamis are the areas where the nuclear power plants are located. In the present work, a numerical simulation of a great tsunamigenic earthquake (M 9) is presented that predicts the generation, propagation, run-up and travel time using TUNAMI N2 for estimating tsunami impacts along the nuclear power plants of the western coast of India. TUNAMI N2 code was designed for shallow water wave equations, which uses the finite-difference method based on staggered-leap frog scheme. Thus, it has potential to simulate a far-field tsunami with much more accuracy than other methods. It is observed that the tsunami will strike along the coast of Jaitapur Nuclear Power Plant (Maharashtra), Tarapur Nuclear Power Plant (Maharashtra), Kaiga Nuclear Power Plant (Karnataka) and Mithi-Virdi Nuclear Power Plant (Gujarat) after 210, 215, 225 and 230 minutes, respectively. Results show that the tsunami run-up is highest for Jaitapur coast (2.32 m). The Mithi-Virdi coast is the least effected (0.93 m) while Kaiga (2.15 m) and Tarapur coast (2.12 m) might have faced quite intense tsunami consequences. The arrival times and run-ups of the tsunami along the coast of different power plants have been calculated since these parameters are of vital importance in mitigation of the coastal hazard, evacuation planning and installation of early warning system in order to save the inhabited communities from the disaste展开更多
Gas hydrates gained a remarkable attention as an unconventional energy resource recently. In order to interpret gas hydrates (part of fluid) and free gas saturated zone accurately, it is essential to implement new tec...Gas hydrates gained a remarkable attention as an unconventional energy resource recently. In order to interpret gas hydrates (part of fluid) and free gas saturated zone accurately, it is essential to implement new technique related to seismic attenuation and velocity dispersion. P wave attenuation and velocity dispersion in porous media made promising imprints for exploration of gas hydrates. The most prominent phenomenon for attenuation and velocity dispersion in porous media is wave induced fluid flow in which wave inhomogeneities are larger than pore size but smaller than wavelength. Numerical simulation technique is applied to analyze frequency dependent velocity dispersion and attenuation in gas hydrates and free gas layer in Makran offshore of Pakistan. Homogeneous and patchy distribution patterns of gas hydrates and free gas within pore spaces of host sediments at lower and higher frequency regime are considered. It is noted that the attenuation and velocity dispersion increase with the increase in gas hydrates saturation. The maximum attenuation is observed at 66% saturation of gas hydrates in the area under investigation. However, in case of water and gas mixture the maximum attenuation and velocity dispersion occur at low gas saturation (~15%). Therefore, based on our numerical simulation, velocity dispersion and attenuation can be used as seismic attributes to differentiate various gas saturations and gas hydrates saturation for Makran offshore area of Pakistan.展开更多
The amount of methane leaked from deep sea cold seeps is enormous and potentially affects the global warming,ocean acidification and global carbon cycle.It is of great significance to study the methane bubble movement...The amount of methane leaked from deep sea cold seeps is enormous and potentially affects the global warming,ocean acidification and global carbon cycle.It is of great significance to study the methane bubble movement and dissolution process in the water column and its output to the atmosphere.Methane bubbles produce strong acoustic impedance in water bodies,and bubble strings released from deep sea cold seeps are called"gas flares"which expressed as flame-like strong backscatter in the water column.We characterized the morphology and movement of methane bubbles released into the water using multibeam water column data at two cold seeps.The result shows that methane at site I reached 920 m water depth without passing through the top of the gas hydrate stability zone(GHSZ,850 m),while methane bubbles at site II passed through the top of the GHSZ(597 m)and entered the non-GHSZ(above 550 m).By applying two methods on the multibeam data,the bubble rising velocity in the water column at sites I and II were estimated to be 9.6 cm/s and 24 cm/s,respectively.Bubble velocity is positively associated with water depth which is inferred to be resulted from decrease of bubble size during methane ascending in the water.Combined with numerical simulation,we concluded that formation of gas hydrate shells plays an important role in helping methane bubbles entering the upper water bodies,while other factors,including water depth,bubble velocity,initial kinetic energy and bubble size,also influence the bubble residence time in the water and the possibility of methane entering the atmosphere.We estimate that methane gas flux at these two sites is 0.4×10~6–87.6×10~6 mol/a which is extremely small compared to the total amount of methane in the ocean body,however,methane leakage might exert significant impact on the ocean acidification considering the widespread distributed cold seeps.In addition,although methane entering the atmosphere is not observed,further research is still needed to understand its potential impact on increasin展开更多
The Durkan Complex is a key tectonic element of the Makran accretionary prism(SE Iran)and it has been interpreted as representing a continental margin succession.We present here a multidisciplinary study of the wester...The Durkan Complex is a key tectonic element of the Makran accretionary prism(SE Iran)and it has been interpreted as representing a continental margin succession.We present here a multidisciplinary study of the western Durkan Complex,which is based on new geological,stratigraphic,biostratigraphic data,as well as geochemical data of the volcanic and meta-volcanic rocks forming this complex.Our data show that this complex consists of distinct tectonic slices showing both non-metamorphic and very low-grade metamorphic deformed successions.Stratigraphic and biostratigraphic data allow us to recognize three types of successions.Type-Ⅰis composed by a Coniacian-early Campanian pelagic succession with intercalation of pillow lavas and minor volcaniclastic rocks.Type-Ⅱsuccession includes a volcanic sequence passing to a volcano-sedimentary sequence with Cenomanian pelagic limestones,followed by a hemipelagic sequence.This succession is characterized by abundant mass-transport deposits.Type-Ⅲsuccession includes volcanic and volcano-sedimentary sequences,which are stratigraphically covered by a Cenomanian platform succession.The latter is locally followed by a hemipelagic sequence.The volcanic rocks in the different successions show alkaline geochemical affinity,suggesting an origin from an oceanic within-plate setting.Our new results indicate that the western Durkan Complex represents fragments of seamounts tectonically incorporated in the Makran accretionary wedge during the latest Late Cretaceous-Paleocene.We propose that incorporation of seamounts in the frontal prism caused a shortening of the whole convergent margin and possibly contributed to controlling the deformation style in the Makran Accretionary Wedge during Late Cretaceous-Paleocene times.展开更多
On one hand,the diversity of activities and on the other hand,the conflicts between beneficiaries necessitate the efficient management and supervision of coastal areas.Accordingly,monitoring and evaluation of such are...On one hand,the diversity of activities and on the other hand,the conflicts between beneficiaries necessitate the efficient management and supervision of coastal areas.Accordingly,monitoring and evaluation of such areas can be considered as a critical factor in the national development and directorship of the sources.With regard to this fact,remote sourcing technologies with use of analytical operations of geographic information systems(GIS),will be remarkably advantageous.Iran’s south-eastern Makran coasts are geopolitically and economically,of importance due to their strategic characteristics but have been neglected and their development and transit infrastructure are significantly beyond the international standards.Therefore,in this paper,with regard to the importance of developing Makran coasts,a Multi-Criterion Decision Analysis(MCDA)method was applied to identify and prioritize the intended criteria and parameters of zoning,in order to establish new maritime zones.The major scope of this study is to employ the satellite data,remote sensing methods,and regional statistics obtained from Jask synoptic station and investigate the region’s status in terms of topography,rainfall rate and temperature changes to reach to a comprehensive monitoring and zoning of the coastal line and to provide a pervasive local data base via use of GIS and MCDA,which will be implemented to construct the coastal regions.In this article,while explaining the steps of coastal monitoring,its main objectives are also explained and the necessary procedures for doing so are presented.Then,the general steps of marine climate identification and study of marine parameters are stated and the final achievements of the coastal monitoring process are determined.In the following,considering that this article focuses on the monitoring of Makran beaches,the method of work in the mentioned region will be described and its specific differences and complexities will be discussed in detail.Also,the impact of such projects on future research results w展开更多
Cold seeps are pervasive along the continental margin worldwide,and are recognized as hotspots for elemental cycling pathway on Earth.In this study,analyses of pore water geochemical compositions of one-400 cm piston ...Cold seeps are pervasive along the continental margin worldwide,and are recognized as hotspots for elemental cycling pathway on Earth.In this study,analyses of pore water geochemical compositions of one-400 cm piston core(S3)and the application of a mass balance model are conducted to assess methane-associated biogeochemical reactions and uncover the relationship of methane in shallow sediment with gas hydrate reservoir at the Makran accretionary wedge off Pakistan.The results revealed that approximately 77%of sulfate is consumed by the predominant biogeochemical process of anaerobic oxidation of methane.However,the estimated sulfate-methane interface depth is-400 cm below sea floor with the methane diffusive flux of 0.039 mol/(m^(2)·a),suggesting the activity of methane seepage.Based on the δ^(13)C_(DIC) mass balance model combined with the contribution proportion of different dissolved inorganic carbon sources,this study calculated the δ^(13)C of the exogenous methane to be-57.9‰,indicating that the exogenous methane may be a mixture source,including thermogenic and biogenic methane.The study of pore water geochemistry at Makran accretionary wedge off Pakistan may have considerable implications for understanding the specific details on the dynamics of methane in cold seeps and provide important evidence for the potential occurrence of subsurface gas hydrate in this area.展开更多
To accurately identify the natural gas hydrates(NGH)in the sea area of the Makran Accretionary Prism,Pakistan,this paper presents the testing and analysis of major and trace elements in sediment samples taken from two...To accurately identify the natural gas hydrates(NGH)in the sea area of the Makran Accretionary Prism,Pakistan,this paper presents the testing and analysis of major and trace elements in sediment samples taken from two stations(S2 and S3)in the area by the China Geological Survey.As shown by testing results,all major elements are slightly different in content between the two stations except SiO2 and CaO.This also applies to the trace elements that include Sr and Ba primarily and Cr,Ni and Zn secondarily.It can be concluded in this study that the tectonic setting of the Makran Accretionary Prism is dominated by oceanic island arc and that provenance of the Makran Accretionary Prism is dominated by felsic igneous provenance,which is at the initial weathering stage and mainly consists of granodiorite.Besides terrigenous detritus,there are sediments possibly originating from Makran-Bela Ophiolite from the northwestern part and Murray Ridge igneous rocks from the southeastern part.The V/Cr,Ni/Co,and V/(V+Ni)ratios indicate that sediments of the two stations are in an oxidation-suboxidation environment.However,the authors infer that the sedimentary environment of the sediments 3.0 m below the seafloor tends to be gradually transformed into a reduction environment by comparison with the Qiongdongnan Basin in the South China Sea where NGH has been discovered.The sediments in the Makran Accretionary Prism are rich in organic matter,with total organic carbon(TOC)content greater than 1%.According to comprehensive research,the organic matter in the sediments mainly originates from marine algae and has high TOC content,which is favorable for the formation of NGH.展开更多
文摘To assist the analysis of tsunami hazards for Qatar coastal areas were using numerical model. By Tsunamis waves created from submarine earthquakes of magnitude of (M<sub>w</sub>) 8.6 and 9.0 in Richard scale along the Makran Subduction Zone (MSZ) as well as coastal landslides with soil volume of 1.25 to 2.0 km<sup>3</sup> along Iranian coast inside the Arabian Gulf is considered. TUNAMI-N2KISR model (Al-Salem) was applied in this study to predict the tsunami propagation and magnitude of Tsunami induced wave heights. The model adopts to solve shallow water equations describing nonlinear long-wave theory. The model also incorporate tidal effect inside the Arabian Gulf as a tsunami travel time from Makran Subduction to Qatar coastline takes more than 9 hours with the tidal range of about 1.6 m during Spring Tide event. For coastal landslides, tsunami generation was simulated using a two-layer numerical model, developed by solving nonlinear long-wave equations. Two-layer model was used to determine initial wave deformation generated by a landslide case. Then TUNAMI-N2KISR was use to simulate tsunami wave propagation. Tsunami waves from landslide scenario arrived after 2.5 - 3 hr with maximum tsunami amplitudes along coasts of Ras laffan-Qatar were 0.8 to 1.0 m. Incorporation of ocean tide is found to impose some small effect on tsunami amplitude at Qatar coastline and nearby areas for the Mw 9.0 earthquake due to small tidal range in this area. In addition, it is found that the tsunami arrival time has become shorter.
基金funded by the National Natural Science Foundation of China(No.42076069).
文摘The Makran accretionary wedge has the smallest subduction angle among any accretionary prism in the world. The factors controlling the spacing and morphological development of its deep thrust faults, as well as the formation mechanism of shallow normal faults, remain unclear. Meanwhile, the factors affecting the continuity of plane faults must be comprehensively discussed. Clarifying the development characteristics and deformation mechanisms of the Makran accretionary wedge is crucial to effectively guide the exploration of gas hydrate deposits in the area. This study aims to interpret seismic data to identify typical structures in the Makran accretionary wedge, including deep imbricate thrust faults, shallow and small normal faults, wedge-shaped piggyback basins, mud diapirs with fuzzy and disorderly characteristics of reflection, décollements with a northward tilt of 1° – 2°, and large seamounts. Physical simulation-based experiments are performed to comprehensively analyze the results of the plane, section, and slices of the wedge. Results reveal that the distances between and shapes of thrust faults in the deep parts of the Makran accretionary wedge are controlled by the bottom décollement. The uplift of the thrust fault-related folds and the upwelling of the mud diapirs primarily contribute to the formation of small normal faults in the shallow part of the area. The mud diapirs originate from plastic material at the bottom, while those that have developed in the area near the trench are larger. Seamounts and mud diapirs break the continuity of fault plane distribution.
基金funded by Darius Project(Head M.Marroni),PRA project of the Pisa University(Head S.Rocchi),IGG-CNR,FAR-2018 Project of the Ferrara University(Head E.Saccani).
文摘The Durkan Complex is a tectonic element of the Makran Accretionary Prism(SE Iran)that includes fragments of Late Cretaceous seamounts.In this paper,the results of map-to micro-scale structural studies of the western Durkan Complex are presented with the aim to describe its structural and tectonometamorphic evolution.The Durkan Complex consists of several tectonic units bordered by mainly NNW-striking thrusts.Three main deformation phases(D_(1),D_(2),and D_(3))are distinguished and likely occurred from the Late Cretaceous to the Miocene–Pliocene.D_(1) is characterized by sub-isoclinal to close and W-verging folds associated with an axial plane foliation and shear zone along the fold limbs.This phase records the accretion of fragments of the seamount within the Makran at blueschist facies metamorphic conditions(160–300℃ and 0.6–1.2 GPa).D_(2) is characterized by open to close folds with subhorizontal axial plane that likely developed during the exhumation of previously accreted seamount fragments.An upper Paleocene–Eocene siliciclastic succession unconformably sealed the D_(1) and D_(2) structures and is,in turn,deformed by W-verging thrust faults typical of D_(3).The latter likely testifies for a Miocene–Pliocene tectonic reworking of the accreted seamount fragments with the activation of out of sequence thrusts.Our results shed light on the mechanism of accretion of seamount materials in the accretionary prisms,suggesting that seamount slope successions favour the localization and propagation of the basal décollement.This study further confirms that the physiography of the subducting plates plays a significant role in the tectonic evolution of the subduction complexes.
文摘The Tortonian–Calabrian strata of Offshore Makran(Pakistan)is investigated for the purpose of reservoir assessment.The stratigraphy and petrophysics indicate that the Neogene sediments have tight reservoir potential with porosities in the range of 3%–9%and 40%–50%water saturation.The mineralogical cross plots indicate a mixed lithology with an abundance of dolomite and calcite,together with minor quartz content and shale.The seismic interpretation demonstrates medium–high amplitude reflection patterns,mud diapirs coupled with onlapping strata and the occurrence of bottom simulating reflectors(BSRs).The BSRs are characterized by diminished amplitude,low continuity and exhibiting acoustic blanking zones.The high formation pressure results indicate overpressure zones,suggesting the occurrence of overpressured shales in the Jal Pari-1A.The presence of mud diapirs and gas chimneys are the result of tectonic forces acting at the junction of the Arabian,Indian and Eurasian plates,whereas,BSRs prove the existence of gas charged sediments supporting the formation of mud diapirism in the region.It is concluded that the high rates of sedimentation during the Neogene are likely to have contributed to the development of the high formation pressure.Revised mud weights,casing policies,pore pressure transients and geophysical inversion studies will help alleviate drilling risks in future exploration strategies.
基金This work was financially supported by the Laboratory for Marine Mineral Resources,Qingdao National Laboratory for Marine Science and Technology(MMRKF201810)the National Natural Science Foundation of China(41606077)This work was also financially supported by the China Geological Survey(DD20190582,DD20191009,DD20160214).
文摘Seabed fluid escape is active in the Makran subduction zone,Arabian Sea.Based on the new highresolution 2D seismic data,acoustic blanking zones and seafloor mounds are identified.Acoustic blanking zones include three kinds of geometries:Bell-shaped,vertically columnar and tilted zones.The bellshaped blanking zone is characterized by weak and discontinuous reflections in the interior and upbending reflections on the top,interpreted as gas chimneys.Vertically columnar blanking zone is interpreted as side-imaged gas chimneys associated with focused fluid flow and topped by a seafloor anomaly expressed as a localized reflection discontinuity,which may together serve as a vent structure.Tilted acoustic blanking zone could be induced by accretionary thrust activity and rapid sedimentation surrounding slope.Seafloor mounds occur at the sites of bell-shaped acoustic blanking zone and may be associated with the material intrusion.Bottom simulating refectors(BSRs)are widely distributed and exhibit a series of characteristics including diminished amplitude,low continuity as well as local shoaling overlapping with these acoustic blanking zones.The large amount of gases dissociated from the gas hydrates migrated upwards and then arrived at the near-seafloor sediments,followed by the formation of the gas hydrates and hence the seafloor mound.
基金This research was supported by projects of China Geological Survey(DD20190582,DD20191009)Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(GML2019ZD0106).
文摘The Makran accretionary prism is located at the junction of the Eurasian Plate,Arabian Plate and Indian Plate and is rich in natural gas hydrate(NGH)resources.It consists of a narrow continental shelf,a broad continental slope,and a deformation front.The continental slope can be further divided into the upper slope,middle slope,and lower slope.There are three types of diapir structure in the accretionary prism,namely mud diapir,mud volcano,and gas chimney.(1)The mud diapirs can be grouped into two types,namely the ones with low arching amplitude and weak-medium activity energy and the ones with high arching amplitude and medium-strong activity energy.The mud diapirs increase from offshore areas towards onshore areas in general,while the ones favorable for the formation of NGH are mainly distributed on the middle slope in the central and western parts of the accretionary prism.(2)The mud volcanoes are mainly concentrated along the anticline ridges in the southern part of the lower slope and the deformation front.(3)The gas chimneys can be grouped into three types,which are located in piggyback basins,active anticline ridges,and inactive anticline ridges,respectively.They are mainly distributed on the middle slope in the central and western parts of the accretionary prism and most of them are accompanied with thrust faults.The gas chimneys located at different tectonic locations started to be active at different time and pierced different horizons.The mud diapirs,mud volcanoes,and gas chimneys and thrust faults serve as the main pathways of gas migration,and thus are the important factors that control the formation,accumulation,and distribution of NGH in the Makran accretionary prism.Mud diapir/gas chimney type hydrate develop in the middle slope,mud volcano type hydrate develop in the southern lower slope and the deformation front,and stepped accretionary prism type hydrate develop on the central and northern lower slope.The middle slope,lower slope and deformation front in the central and western parts of the Mak
文摘The Napag is the biggest Mud Volcano at Makran in Iran. The main aim of this research is the investigation of geologic setting and geographic situation of Napag Mud Volcano as a well-known mud diapir at Makran on the south eastern margin of Iran. The Napag Mud Volcano has been formed during quaternary of as a conical hill on the flat plain in coastal region Oman Sea. There are badlands area and several mud volcanoes that they have been triggered by longitudinal normal faults. This normal faults have been developed in neotectonic regime by the roll-back of oceanic lithosphere (beneath of Oman Sea). Finally, the main characteristics of the Napag mud diapir are presented.
文摘Makran zone is one of the largest accretionary wedges in the world. This research had used methods such as studies of Office and library, field observation and surveying that several field visits, sampling, registered structural evidence, Laboratory studies, Data analysis, interpretation and conclusions. The most important objective of this study is assessment of Tectonics and hazard Potential in Coasts the Oman Sea based on tectonics and sedimentology. The northward movement and subduction of Oman oceanic lithosphere beneath Iranian micro-plate at a very shallow angle and at high rate is responsible for active orogenesis and uplift. Detailed seismological and geological information in planning is extremely essential to avoid any disaster. It is to be remembered that seismicity does not remain fixed in an area but migrates slowly with time. Thus, the planners are expected to be more concerned with the building code and prevention strategies. It is also important to mention that the Coastal zones are always vulnerable to natural hazards and liquefaction. The geomorphology of an area is the first indicator of on-going tectonic activity. In order to measure the amount of deformation due to tectonic processes, the initial geometry of the geomorphic markers is reconstructed accurately. Study of sediments shows that abundant shell fragments organized in laminae also favor a storm origin. Storm deposits contain no internal mud layers and rarely contain pieces of mud. Maximum deposit thickness is near the shore, and landward thinning of the deposit is commonly abrupt. Storm deposits fill in topographic lows, and the upper surface is relatively uniform in elevation alongshore. Finally, landforms of tectonically active regions and sediments are controlling factors interactions between tectonic, sedimentary, climatic, and surficial processes.
基金the Research Council of University of Sistan and Baluchestan which has supported the project
文摘In this paper, remote sensing techniques,as well as field studies, have been used to investigate the geomorphological processes and landscape evolution along the Saravan Fault, SE Iran to highlight how topographic features were influenced by active tectonics. Quantitative geomorphic analysis was carried out using mountain-front sinuosity(Smf),valley floor width-valley height ratio(Vf), drainage basin asymmetry factor(Af), Hypsometric integral(Hi), drainage basin shape index(Bs), mean axial slope of channel(MASC), standard deviation of topography(STD) and index of active tectonic(Iat).Remote sensing techniques, as well as field studies revealed that the Saravan Fault have three parts trending N-S, NW-SE, and E-W. Obtained results show that basins with high Iat index are located at where the strike of the Saravan Faults changes and where several strike-slip faults are crossed the Saravan fault.
文摘The major seismicity source in the northern Arabian Sea is the Makran Subduction Zone (MSZ) that defines the tectonic boundary between the Arabian plate and the Eurasian plate, located offshore Iran and Pakistan over which an instrumentally registered earthquake (Mw 8.1) generated a tsunami on 27 November, 1945. It has caused severe cataclysm to a vulnerable population along the surrounding coastlines, including India. It has been on a long seismic quiescence since this last event. The population and industrialization have exponentially increased along the coastal areas in last half decade. The highly exposed coastal locations to the tsunamis are the areas where the nuclear power plants are located. In the present work, a numerical simulation of a great tsunamigenic earthquake (M 9) is presented that predicts the generation, propagation, run-up and travel time using TUNAMI N2 for estimating tsunami impacts along the nuclear power plants of the western coast of India. TUNAMI N2 code was designed for shallow water wave equations, which uses the finite-difference method based on staggered-leap frog scheme. Thus, it has potential to simulate a far-field tsunami with much more accuracy than other methods. It is observed that the tsunami will strike along the coast of Jaitapur Nuclear Power Plant (Maharashtra), Tarapur Nuclear Power Plant (Maharashtra), Kaiga Nuclear Power Plant (Karnataka) and Mithi-Virdi Nuclear Power Plant (Gujarat) after 210, 215, 225 and 230 minutes, respectively. Results show that the tsunami run-up is highest for Jaitapur coast (2.32 m). The Mithi-Virdi coast is the least effected (0.93 m) while Kaiga (2.15 m) and Tarapur coast (2.12 m) might have faced quite intense tsunami consequences. The arrival times and run-ups of the tsunami along the coast of different power plants have been calculated since these parameters are of vital importance in mitigation of the coastal hazard, evacuation planning and installation of early warning system in order to save the inhabited communities from the disaste
文摘Gas hydrates gained a remarkable attention as an unconventional energy resource recently. In order to interpret gas hydrates (part of fluid) and free gas saturated zone accurately, it is essential to implement new technique related to seismic attenuation and velocity dispersion. P wave attenuation and velocity dispersion in porous media made promising imprints for exploration of gas hydrates. The most prominent phenomenon for attenuation and velocity dispersion in porous media is wave induced fluid flow in which wave inhomogeneities are larger than pore size but smaller than wavelength. Numerical simulation technique is applied to analyze frequency dependent velocity dispersion and attenuation in gas hydrates and free gas layer in Makran offshore of Pakistan. Homogeneous and patchy distribution patterns of gas hydrates and free gas within pore spaces of host sediments at lower and higher frequency regime are considered. It is noted that the attenuation and velocity dispersion increase with the increase in gas hydrates saturation. The maximum attenuation is observed at 66% saturation of gas hydrates in the area under investigation. However, in case of water and gas mixture the maximum attenuation and velocity dispersion occur at low gas saturation (~15%). Therefore, based on our numerical simulation, velocity dispersion and attenuation can be used as seismic attributes to differentiate various gas saturations and gas hydrates saturation for Makran offshore area of Pakistan.
基金The National Key Research and Development Plan under contract Nos 2018YFC0310000 and 2016YFC0304905-03the National Natural Science Foundation of China under contract No.41602149China Geological Survey Project under contract Nos DD20190582,DD20191009 and DD20160214。
文摘The amount of methane leaked from deep sea cold seeps is enormous and potentially affects the global warming,ocean acidification and global carbon cycle.It is of great significance to study the methane bubble movement and dissolution process in the water column and its output to the atmosphere.Methane bubbles produce strong acoustic impedance in water bodies,and bubble strings released from deep sea cold seeps are called"gas flares"which expressed as flame-like strong backscatter in the water column.We characterized the morphology and movement of methane bubbles released into the water using multibeam water column data at two cold seeps.The result shows that methane at site I reached 920 m water depth without passing through the top of the gas hydrate stability zone(GHSZ,850 m),while methane bubbles at site II passed through the top of the GHSZ(597 m)and entered the non-GHSZ(above 550 m).By applying two methods on the multibeam data,the bubble rising velocity in the water column at sites I and II were estimated to be 9.6 cm/s and 24 cm/s,respectively.Bubble velocity is positively associated with water depth which is inferred to be resulted from decrease of bubble size during methane ascending in the water.Combined with numerical simulation,we concluded that formation of gas hydrate shells plays an important role in helping methane bubbles entering the upper water bodies,while other factors,including water depth,bubble velocity,initial kinetic energy and bubble size,also influence the bubble residence time in the water and the possibility of methane entering the atmosphere.We estimate that methane gas flux at these two sites is 0.4×10~6–87.6×10~6 mol/a which is extremely small compared to the total amount of methane in the ocean body,however,methane leakage might exert significant impact on the ocean acidification considering the widespread distributed cold seeps.In addition,although methane entering the atmosphere is not observed,further research is still needed to understand its potential impact on increasin
基金funded by Darius Project(Head M.Marroni)by the PRA project of the Pisa University(Head S.Rocchi),grants from IGG-CNRFAR-2018 Project of the Ferrara University(Head E.S.and V.L.)。
文摘The Durkan Complex is a key tectonic element of the Makran accretionary prism(SE Iran)and it has been interpreted as representing a continental margin succession.We present here a multidisciplinary study of the western Durkan Complex,which is based on new geological,stratigraphic,biostratigraphic data,as well as geochemical data of the volcanic and meta-volcanic rocks forming this complex.Our data show that this complex consists of distinct tectonic slices showing both non-metamorphic and very low-grade metamorphic deformed successions.Stratigraphic and biostratigraphic data allow us to recognize three types of successions.Type-Ⅰis composed by a Coniacian-early Campanian pelagic succession with intercalation of pillow lavas and minor volcaniclastic rocks.Type-Ⅱsuccession includes a volcanic sequence passing to a volcano-sedimentary sequence with Cenomanian pelagic limestones,followed by a hemipelagic sequence.This succession is characterized by abundant mass-transport deposits.Type-Ⅲsuccession includes volcanic and volcano-sedimentary sequences,which are stratigraphically covered by a Cenomanian platform succession.The latter is locally followed by a hemipelagic sequence.The volcanic rocks in the different successions show alkaline geochemical affinity,suggesting an origin from an oceanic within-plate setting.Our new results indicate that the western Durkan Complex represents fragments of seamounts tectonically incorporated in the Makran accretionary wedge during the latest Late Cretaceous-Paleocene.We propose that incorporation of seamounts in the frontal prism caused a shortening of the whole convergent margin and possibly contributed to controlling the deformation style in the Makran Accretionary Wedge during Late Cretaceous-Paleocene times.
文摘On one hand,the diversity of activities and on the other hand,the conflicts between beneficiaries necessitate the efficient management and supervision of coastal areas.Accordingly,monitoring and evaluation of such areas can be considered as a critical factor in the national development and directorship of the sources.With regard to this fact,remote sourcing technologies with use of analytical operations of geographic information systems(GIS),will be remarkably advantageous.Iran’s south-eastern Makran coasts are geopolitically and economically,of importance due to their strategic characteristics but have been neglected and their development and transit infrastructure are significantly beyond the international standards.Therefore,in this paper,with regard to the importance of developing Makran coasts,a Multi-Criterion Decision Analysis(MCDA)method was applied to identify and prioritize the intended criteria and parameters of zoning,in order to establish new maritime zones.The major scope of this study is to employ the satellite data,remote sensing methods,and regional statistics obtained from Jask synoptic station and investigate the region’s status in terms of topography,rainfall rate and temperature changes to reach to a comprehensive monitoring and zoning of the coastal line and to provide a pervasive local data base via use of GIS and MCDA,which will be implemented to construct the coastal regions.In this article,while explaining the steps of coastal monitoring,its main objectives are also explained and the necessary procedures for doing so are presented.Then,the general steps of marine climate identification and study of marine parameters are stated and the final achievements of the coastal monitoring process are determined.In the following,considering that this article focuses on the monitoring of Makran beaches,the method of work in the mentioned region will be described and its specific differences and complexities will be discussed in detail.Also,the impact of such projects on future research results w
基金The National Natural Science Foundation of China under contract Nos 41606087,91858208,and 42076069the Taishan Scholar Special Experts Project under contract No.TS201712079+1 种基金the National Key Basic Research and Development Program of China under contract No.2017YFC0307704the Marine Geological Survey Program of China Geological Survey under contract Nos DD20190518 and DD20190819。
文摘Cold seeps are pervasive along the continental margin worldwide,and are recognized as hotspots for elemental cycling pathway on Earth.In this study,analyses of pore water geochemical compositions of one-400 cm piston core(S3)and the application of a mass balance model are conducted to assess methane-associated biogeochemical reactions and uncover the relationship of methane in shallow sediment with gas hydrate reservoir at the Makran accretionary wedge off Pakistan.The results revealed that approximately 77%of sulfate is consumed by the predominant biogeochemical process of anaerobic oxidation of methane.However,the estimated sulfate-methane interface depth is-400 cm below sea floor with the methane diffusive flux of 0.039 mol/(m^(2)·a),suggesting the activity of methane seepage.Based on the δ^(13)C_(DIC) mass balance model combined with the contribution proportion of different dissolved inorganic carbon sources,this study calculated the δ^(13)C of the exogenous methane to be-57.9‰,indicating that the exogenous methane may be a mixture source,including thermogenic and biogenic methane.The study of pore water geochemistry at Makran accretionary wedge off Pakistan may have considerable implications for understanding the specific details on the dynamics of methane in cold seeps and provide important evidence for the potential occurrence of subsurface gas hydrate in this area.
基金This work was funded by the projects of the National Natural Science Foundation of China(91858208,42076069)the project of China Geological Survey(DD20190581)。
文摘To accurately identify the natural gas hydrates(NGH)in the sea area of the Makran Accretionary Prism,Pakistan,this paper presents the testing and analysis of major and trace elements in sediment samples taken from two stations(S2 and S3)in the area by the China Geological Survey.As shown by testing results,all major elements are slightly different in content between the two stations except SiO2 and CaO.This also applies to the trace elements that include Sr and Ba primarily and Cr,Ni and Zn secondarily.It can be concluded in this study that the tectonic setting of the Makran Accretionary Prism is dominated by oceanic island arc and that provenance of the Makran Accretionary Prism is dominated by felsic igneous provenance,which is at the initial weathering stage and mainly consists of granodiorite.Besides terrigenous detritus,there are sediments possibly originating from Makran-Bela Ophiolite from the northwestern part and Murray Ridge igneous rocks from the southeastern part.The V/Cr,Ni/Co,and V/(V+Ni)ratios indicate that sediments of the two stations are in an oxidation-suboxidation environment.However,the authors infer that the sedimentary environment of the sediments 3.0 m below the seafloor tends to be gradually transformed into a reduction environment by comparison with the Qiongdongnan Basin in the South China Sea where NGH has been discovered.The sediments in the Makran Accretionary Prism are rich in organic matter,with total organic carbon(TOC)content greater than 1%.According to comprehensive research,the organic matter in the sediments mainly originates from marine algae and has high TOC content,which is favorable for the formation of NGH.
