Objective The occurrence of the devastating Wenchuan earthquake not only caused huge economic loss and deaths but also raised a question whether or not it would trigger any destructive earthquakes on its neighboring s...Objective The occurrence of the devastating Wenchuan earthquake not only caused huge economic loss and deaths but also raised a question whether or not it would trigger any destructive earthquakes on its neighboring segments in the Longmenshan Thrust Zone （LTZ） in the future.展开更多
The Himalaya, a fold\|and\|thrust belt in the northern margin of the Indian continent, is characterized by thrust tectoncis (Schelling and Arita, 1991). It consists mainly of three thrust\|bounded lithotectonic units:...The Himalaya, a fold\|and\|thrust belt in the northern margin of the Indian continent, is characterized by thrust tectoncis (Schelling and Arita, 1991). It consists mainly of three thrust\|bounded lithotectonic units: from south to north the Sub\|Himalayan imbricate zone, the Lesser Himalayan thrust package (LH) and the Higher Himalayan thrust sheet (HH) with the overlying Tethys Himalayan sequence. These units are separated by a series of propagated thrusts, i.e. from south to north the Himalayan Frontal Fault (HFF), Main Boundary Thrust (MBT) and Main Central Thrust (MCT). These thrusts are splays off of an underlying mid\|crustal subhorizontal d$B;D(Jollement (Main Detachmen Trust or Main Himalayan Thrust), and were propagated southward with time. Among these thrusts the MCT is most important intracrustal thrust in considering the geological evolution of the Himalaya, and is controversial regarding its location and nature. In western and eastern Nepal the Higher Himalayan Crystalline sheet is thrust over the Lesser Himalayan rocks along the MCT. In the Kathmandu area of central Nepal also the high\|grade rocks of the HH with the overlying Tethyan sediments covers southward the Lesser Himalayan rocks, and form the Kathmandu nappe. In the north of the Kathmandu nappe the Higher Himalayan crystallines are skirted by the Main Central Thrust zone (MCT zone) which consists of green and black phyllites with sporadic garnet snow\|ball garnet and calcareous schist associated with characteristic mylonitic augen gneiss. The southern margin of the nappe is bounded by the Mahabharat Thrust (MT: Stoecklin, 1990) with a narrow zone of the LH which is cut by the MBT. But the relationship of the MCT in the north and the MT in the south is disputable and important (Arita et al., 1997: Rai et al., 1998: Upreti and Le Fort, 1999), and in the margin of the Kathmandu nappe the MCT zone has not been confirmed.展开更多
Triangle zones, generally found in foreland fold-and-thrust belts, serve as favorable objects of petroleum exploration. Taking the Dabashan foreland belt as an example, we studied the formation and development of tria...Triangle zones, generally found in foreland fold-and-thrust belts, serve as favorable objects of petroleum exploration. Taking the Dabashan foreland belt as an example, we studied the formation and development of triangle zones, and investigated the effect of d^collements and the mechanical contrast of lithology by employing the method of physical modeling. Four experimental models were conducted in the work. The results showed that ＇sand wedges＇ grew episodically, recorded by deformational length, height and slope angle. The height versus shortening rate presented an S-shape curve, and uplifting occurred successively in the direction of the foreland belt. During the formation of the triangle zone, layer-parallel shortening took place at the outset; deformation decoupling then occurred between the upper and lower brittle layers, divided by a middle-embedded silicone polymers layer. The upper brittle layers deformed mainly by folding, while the lower sand layers by thrusting. As shortening continued, the geometry of a triangle zone was altered. We consider that the triangle zone in the Dabashan foreland belt was modified from an early one based on available seismic profiles and the experimental results. In addition, dccollements and mechanical contrast impose significant influence on structural development, which can directly give rise to structural discrepancies. More d^collements and obvious mechanical contrast between brittle layers can promote the coupling between the upper and lower brittle layers. Basal d^collement controls the whole deformation and decreases the slope angle of the wedge, while roof d^collement determines whether a triangle zone can be formed.展开更多
Fission track geological chronology is an effective method of study on tectonic movement of fault zone. Apatite fission track (AFT) dating analyses of 9-apatite and 4-zircon samples collected from Lhasa to Langkazi, -...Fission track geological chronology is an effective method of study on tectonic movement of fault zone. Apatite fission track (AFT) dating analyses of 9-apatite and 4-zircon samples collected from Lhasa to Langkazi, -70-km-long in SN provide an understanding of the age and the uplifting of both sides of the Yarlung Zangbo Thrust Zone (YZTZ) in this work. The AFT ages range from-37 to 14 Ma, indicating the time of major tectono-thermal events, i.e. the continent-continent collision along the YZTZ. Based on the relationship between the AFT ages and the sample elevations, there were two tectonic active periods: -37-20 Ma and 20-14 Ma. In the first period the tectonic event did not bring on differential uplifting. Rapid differential uplifting with rapid cooling, resulting from thrusting, took place in the second period. The vertical displacement was -1020 m and total -2.9 km of overburden has been removed from the present-day surface since cooling below -110°C began. The maximum cooling and denudation展开更多
The Arun mega\|antiform, a large N—S structure transversal to the tectonic trend of the E Nepal Himalaya, is a tectonic window offering a complete section of the Himalayan nappe pile, from the Lesser Himalayan zone t...The Arun mega\|antiform, a large N—S structure transversal to the tectonic trend of the E Nepal Himalaya, is a tectonic window offering a complete section of the Himalayan nappe pile, from the Lesser Himalayan zone to the Tethyan Himalaya. At the northern end of the Arun tectonic window (ATW), the Ama Drime—Nyonno Ri range of south Tibet exposes a section of that portion of the Main Central Thrust (MCT) zone and Lesser Himalayan Crystallines (LHC) which elsewhere in Nepal is concealed below the overlying Higher Himalayan Crystalline (HHC) nappe (Fig. 1). As throughout the Himalaya at the structural level of the MCT, the ATW is characterized by an inverted metamorphic field gradient characterized by a progression from chlorite to sillimanite grade from low to high structural levels of the nappe pile. Metamorphic peak temperatures rise from circa 400℃ in the pelitic and psammitic Precambrian metasediments of the Lesser Himalayan Tumlingtar Unit, to 550～620℃ in the overlying LHC, to over 700℃ in the muscovite\|free Barun Gneiss, the lowermost HHC unit in the Arun valley.展开更多
Segmentation of the thrust fault zone is a basic problem for earthquake hazard evaluation. The Yingjing-Mabian-Yanjin thrust fault zone is an important seismic belt NW-trending in the southeast margin of the Qinghal-X...Segmentation of the thrust fault zone is a basic problem for earthquake hazard evaluation. The Yingjing-Mabian-Yanjin thrust fault zone is an important seismic belt NW-trending in the southeast margin of the Qinghal-Xizang （Tibet） plateau. The longitudinal faults in the thrust zone are mainly of the thrust slipping type. The late Quaternary motion modes and displacement rates are quite different from north to south. Investigation on valleys across the fault shows that the transverse faults are mainly of dextral strike-slipping type with a bit dip displacement. Based on their connections with the longitudinal faults, three types of transverse faults are generalized, namely： the separate fault, the transform fault and the tear fault, and their functions in the segmentation of the thrust fault zone are compared. As the result, the Yingjing-Mabian-Yanjin thrust fault zone is divided into three segments, and earthquakes occurring in these three segments are compared. The tri-section of the Yingjing-Mabian-Yanjin thrust fault zone identified by transverse fault types reflects, on the one hand, the differences in slip rate, earthquake magnitude and pace from each segment, and the coherence of earthquake rupturing pace on the other hand. It demonstrates that the transverse faults control the segmentation to a certain degree, and each type of the transverse faults plays a different role.展开更多
The map expression of ＂abrupt＂ changes in lateral stratigraphic level of a thrust fault has been traditionally interpreted to be a result of the presence of （1） a lateral （or oblique） thrust-ramp, or （2） a fro...The map expression of ＂abrupt＂ changes in lateral stratigraphic level of a thrust fault has been traditionally interpreted to be a result of the presence of （1） a lateral （or oblique） thrust-ramp, or （2） a frontal ramp with displacement gradient, and/or （3） a combination of these geometries. These geometries have been used to interpret the structures near transverse zones in fold-thrust belts （FTB）. This contribution outlines an alternative explanation that can result in the same map pattern by lateral variations in stratigraphy along the strike of a low angle thrust fault. We describe the natural example of the Leamington transverse zone, which marks the southern margin of the Pennsylvanian-Permian Oquirrh basin with genetically related lateral stratigraphic variations in the North American Sevier FTB. Thus, the observed map pattern at this zone is closely related to lateral stratigraphic variations along the strike of a horizontal fault. Even though the present-day erosional level shows the map pattern that could be interpreted as a lateral ramp, the observed structures along the Leamington zone most likely share the effects of the presence of a lateral （or oblique） ramp, lateral stratigraphic variations along the fault trace, and the displacement gradient.展开更多
The main aim of this research is to get a better knowledge and understanding of the micro-scale oscillatory networks behavior in the solid propellants reactionary zones. Fundamental understanding of the micro-and nano...The main aim of this research is to get a better knowledge and understanding of the micro-scale oscillatory networks behavior in the solid propellants reactionary zones. Fundamental understanding of the micro-and nano-scale combustion mechanisms is essential to the development and further improvement of the next-generation technologies for extreme control of the solid propellant thrust. Both experiments and theory confirm that the micro-and nano-scale oscillatory networks excitation in the solid propellants reactionary zones is a rather universal phenomenon. In accordance with our concept,the micro-and nano-scale structures form both the fractal and self-organized wave patterns in the solid propellants reactionary zones. Control by the shape, the sizes and spacial orientation of the wave patterns allows manipulate by the energy exchange and release in the reactionary zones. A novel strategy for enhanced extreme thrust control in solid propulsion systems are based on manipulation by selforganization of the micro-and nano-scale oscillatory networks and self-organized patterns formation in the reactionary zones with use of the system of acoustic waves and electro-magnetic fields, generated by special kind of ring-shaped electric discharges along with resonance laser radiation. Application of special kind of the ring-shaped electric discharges demands the minimum expenses of energy and opens prospects for almost inertia-free control by combustion processes. Nano-sized additives will enhance self-organizing and self-synchronization of the micro-and nano-scale oscillatory networks on the nanometer scale. Suggested novel strategy opens the door for completely new ways for enhanced extreme thrust control of the solid propulsion systems.展开更多
A contact zone sandwiched between an arc and an oceanic crust was discoveredin the Laohushan area in the present study. It consists of a series of north-dipping imbricatedthrust sheets and is exposed on the surface as...A contact zone sandwiched between an arc and an oceanic crust was discoveredin the Laohushan area in the present study. It consists of a series of north-dipping imbricatedthrust sheets and is exposed on the surface as a narrow arcuate belt, which extends for about 30 kmin an E-W direction and measures about 1-3 km wide. Lithologically, it can be divided into foursubzones. Subzone 1 consists of meta-andesite and metasandstone; subzone 2, psammitic schists;subzone 3, psammitic and pelitic schists, quartz diorite and hornfelses; and subzone 4, metagabbro,epidote amphibolite and pelitic schists. The metamorphism has the following grading sequence: lowgreenschist facies in subzone 1 - > high greenschist facies in subzone 2 - > low amphibolite fadesin subzone 3 - > epidote amphibolite facies in subzone 4. Petrographic and geochemical evidenceshows that rocks in subzones 1, 2 and 3 are arc rocks, whereas those of subzone 4 are oceaniccrustal rocks. The metamorphic mineral assemblages and especially mineral chemistry of the bluishgreen amphibole from the pelitic schists and epidote amphibolite of subzone 4 suggest that the rocksof the contact zone were metamorphosed at a pressure of up to 0.69 GPa. It is thought that theLate-Mid Ordovician oceanic lithosphere of a back-arc basin was underthrust northerly beneath an arcto a depth of 20-23 km, where the basaltic rocks and gabbro were converted to epidote amphiboliteand metagabbro respectively. Then, the root rocks of the arc and these metamorphosed oceanic rockswere brought up to shallower depths by thrust faults to form a contact zone between the arc and theoceanic crust in the Laohushan area.展开更多
Field investigation and seismic section explanation showed that the Longmen Mountain Thrust Belt has obvious differential deformation： zonation, segmentation and stratification. Zonation means that, from NW to NE, th...Field investigation and seismic section explanation showed that the Longmen Mountain Thrust Belt has obvious differential deformation： zonation, segmentation and stratification. Zonation means that, from NW to NE, the Longmen Mountain Thrust Belt can be divided into the Songpan- Garz~ Tectonic Belt, ductile deformation belt, base involved thrust belt, frontal fold-thrust belt, and foreland depression. Segmentation means that it can be divided into five segments from north to south： the northern segment, the Anxian Transfer Zone, the center segment, the Guanxian Transfer Zone and the southern segment. Stratification means that the detachment layers partition the structural styles in profile. The detachment layers in the Longmen Mountain Thrust Belt can be classified into three categories： the deep-level detachment layers, including the crust-mantle system detachment layer, intracrustal detachment layer, and Presinian system basal detachment layer; the middle-level detachment layers, including Cambrian-Ordovician detachment layer, Silurian detachment layer, etc.; and shallow-level detachment layers, including Upper Triassic Xujiahe Formation detachment layer and the Jurassic detachment layers. The multi-level detachment layers have a very important effect on the shaping and evolution of Longmen Mountain Thrust Belt.展开更多
Abstract The nearly E-W-trending Aqqikkudug-Weiya zone, more than 1000 km long and about 30 km wide, is an important segment in the Central Asian tectonic framework. It is distributed along the northern margin of the ...Abstract The nearly E-W-trending Aqqikkudug-Weiya zone, more than 1000 km long and about 30 km wide, is an important segment in the Central Asian tectonic framework. It is distributed along the northern margin of the Central Tianshan belt in Xinjiang, NW China and is composed of mylonitized Early Palaeozoic greywacke, volcanic rocks, ophiolitic blocks as a mélange complex, HP/LT-type bleuschist blocks and mylonitized Neoproterozoic schist, gneiss and orthogneiss. Nearly vertical mylonitic foliation and sub-horizontal stretching lineation define its strike-slip feature; various kinematic indicators, such as asymmetric folds, non-coaxial asymmetric macro- to micro-structures and C-axis fabrics of quartz grains of mylonites, suggest that it is a dextral strike-slip ductile shear zone oriented in a nearly E-W direction characterized by “flower” strusture with thrusting or extruding across the zone toward the two sides and upright folds with gently plunging hinges. The Aqqikkudug-Weiya zone experienced at least two stages of ductile shear tectonic evolution: Early Palaeozoic north vergent thrusting ductile shear and Late Carboniferous-Early Permian strike-slip deformation. The strike-slip ductile shear likely took place during Late Palaeozoic time, dated at 269±5 Ma by the40Ar/39Ar analysis on neo-muscovites. The strike-slip deformation was followed by the Hercynian violent S-type granitic magmatism. Geodynamical analysis suggests that the large-scale dextral strike-slip ductile shearing is likely the result of intracontinental adjustment deformation after the collision of the Siberian continental plate towards the northern margin of the Tarim continental plate during the Late Carboniferous. The Himalayan tectonism locally deformed the zone, marked by final uplift, brittle layer-slip and step-type thrust faults, transcurrent faults and E-W-elongated Mesozoic-Cenozoic basins.展开更多
Accommodation of continental convergence by crustal thickening and lateral transport is mainly featured as strike-slip faulting along the trends roughly orthogonai to the orientation of plate convergence. This style o...Accommodation of continental convergence by crustal thickening and lateral transport is mainly featured as strike-slip faulting along the trends roughly orthogonai to the orientation of plate convergence. This style of faulting will affect seismicity of the involving areas which can be proved in low seismic zones by determining regional stress pattern using numerical methods. Accordingly, the stress distribution and deformation pattern of the South Sanandaj-Sirjan zone in the northeastern part of the Iranian-Arabian collision zone is investigated here using a three dimen-sional mechanical model. The modeled area is bounded between the Zagros thrust fault on the west and Dehshir-Baft fault in the east. The model is composed of three layers： the upper two layers represent the upper brittle and lower ductile crust of the collided continent and the lowest layer represents the lithospheric mantle. The upper crust behaves as an elastic material while the lower crust is considered as a non-Newtonian viscous fluid layer. The lithospheric mantle is taken as a low-viscosity material which is not allowed to move in any direction relative to the overlying layers. The Zagros thrust fault was treated with two different dip values saying 90° and 45° but Dehshir-Baft fault was modeled as a vertical fault and allowed to have a dextral movement regarding to the existing evidence. The driving mechanism applied to the western side of the model was chosen considering two different approaches including a kinematic approach （the Arabian-Eurasian convergence velocity; 35 mm/yr） and a dynamic approach （an external boundary force equal to 3.55E＋17 N）. The resulted stress field indicates an orogen-parallel component of right lateral shear along the Zagros fault implying a rotational deformation pattern within the modeled region that suggests a stress partitioning in the study area. The pattern also indicates a stress accumulation towards the south which could be a reason for the regional seismic quiescence between the two seismic Zagros thrust and Dehshir-Baft faults. Based on the present modeling results, it seems that high stress localization on the boundary faults can be a support of block structure approach or quasi-rigid blocks deformation within the study area. The resultant patterns of stress and displacement fields are generally totally comparable with plate boundary shear zones and have been proven by field data.展开更多
基金jointly supported by the National Natural Science Foundation of China(grant No.41602206)the International Science&Technology Cooperation Program of China(grant No.2011DFG23400)
文摘Objective The occurrence of the devastating Wenchuan earthquake not only caused huge economic loss and deaths but also raised a question whether or not it would trigger any destructive earthquakes on its neighboring segments in the Longmenshan Thrust Zone （LTZ） in the future.
文摘The Himalaya, a fold\|and\|thrust belt in the northern margin of the Indian continent, is characterized by thrust tectoncis (Schelling and Arita, 1991). It consists mainly of three thrust\|bounded lithotectonic units: from south to north the Sub\|Himalayan imbricate zone, the Lesser Himalayan thrust package (LH) and the Higher Himalayan thrust sheet (HH) with the overlying Tethys Himalayan sequence. These units are separated by a series of propagated thrusts, i.e. from south to north the Himalayan Frontal Fault (HFF), Main Boundary Thrust (MBT) and Main Central Thrust (MCT). These thrusts are splays off of an underlying mid\|crustal subhorizontal d$B;D(Jollement (Main Detachmen Trust or Main Himalayan Thrust), and were propagated southward with time. Among these thrusts the MCT is most important intracrustal thrust in considering the geological evolution of the Himalaya, and is controversial regarding its location and nature. In western and eastern Nepal the Higher Himalayan Crystalline sheet is thrust over the Lesser Himalayan rocks along the MCT. In the Kathmandu area of central Nepal also the high\|grade rocks of the HH with the overlying Tethyan sediments covers southward the Lesser Himalayan rocks, and form the Kathmandu nappe. In the north of the Kathmandu nappe the Higher Himalayan crystallines are skirted by the Main Central Thrust zone (MCT zone) which consists of green and black phyllites with sporadic garnet snow\|ball garnet and calcareous schist associated with characteristic mylonitic augen gneiss. The southern margin of the nappe is bounded by the Mahabharat Thrust (MT: Stoecklin, 1990) with a narrow zone of the LH which is cut by the MBT. But the relationship of the MCT in the north and the MT in the south is disputable and important (Arita et al., 1997: Rai et al., 1998: Upreti and Le Fort, 1999), and in the margin of the Kathmandu nappe the MCT zone has not been confirmed.
文摘Triangle zones, generally found in foreland fold-and-thrust belts, serve as favorable objects of petroleum exploration. Taking the Dabashan foreland belt as an example, we studied the formation and development of triangle zones, and investigated the effect of d^collements and the mechanical contrast of lithology by employing the method of physical modeling. Four experimental models were conducted in the work. The results showed that ＇sand wedges＇ grew episodically, recorded by deformational length, height and slope angle. The height versus shortening rate presented an S-shape curve, and uplifting occurred successively in the direction of the foreland belt. During the formation of the triangle zone, layer-parallel shortening took place at the outset; deformation decoupling then occurred between the upper and lower brittle layers, divided by a middle-embedded silicone polymers layer. The upper brittle layers deformed mainly by folding, while the lower sand layers by thrusting. As shortening continued, the geometry of a triangle zone was altered. We consider that the triangle zone in the Dabashan foreland belt was modified from an early one based on available seismic profiles and the experimental results. In addition, dccollements and mechanical contrast impose significant influence on structural development, which can directly give rise to structural discrepancies. More d^collements and obvious mechanical contrast between brittle layers can promote the coupling between the upper and lower brittle layers. Basal d^collement controls the whole deformation and decreases the slope angle of the wedge, while roof d^collement determines whether a triangle zone can be formed.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 40072068)the President Fund of the Chinese Academy of Sciences (Grant No. 99-775)the Laboratory of Nuclear Analysis.
文摘Fission track geological chronology is an effective method of study on tectonic movement of fault zone. Apatite fission track (AFT) dating analyses of 9-apatite and 4-zircon samples collected from Lhasa to Langkazi, -70-km-long in SN provide an understanding of the age and the uplifting of both sides of the Yarlung Zangbo Thrust Zone (YZTZ) in this work. The AFT ages range from-37 to 14 Ma, indicating the time of major tectono-thermal events, i.e. the continent-continent collision along the YZTZ. Based on the relationship between the AFT ages and the sample elevations, there were two tectonic active periods: -37-20 Ma and 20-14 Ma. In the first period the tectonic event did not bring on differential uplifting. Rapid differential uplifting with rapid cooling, resulting from thrusting, took place in the second period. The vertical displacement was -1020 m and total -2.9 km of overburden has been removed from the present-day surface since cooling below -110°C began. The maximum cooling and denudation
文摘The Arun mega\|antiform, a large N—S structure transversal to the tectonic trend of the E Nepal Himalaya, is a tectonic window offering a complete section of the Himalayan nappe pile, from the Lesser Himalayan zone to the Tethyan Himalaya. At the northern end of the Arun tectonic window (ATW), the Ama Drime—Nyonno Ri range of south Tibet exposes a section of that portion of the Main Central Thrust (MCT) zone and Lesser Himalayan Crystallines (LHC) which elsewhere in Nepal is concealed below the overlying Higher Himalayan Crystalline (HHC) nappe (Fig. 1). As throughout the Himalaya at the structural level of the MCT, the ATW is characterized by an inverted metamorphic field gradient characterized by a progression from chlorite to sillimanite grade from low to high structural levels of the nappe pile. Metamorphic peak temperatures rise from circa 400℃ in the pelitic and psammitic Precambrian metasediments of the Lesser Himalayan Tumlingtar Unit, to 550～620℃ in the overlying LHC, to over 700℃ in the muscovite\|free Barun Gneiss, the lowermost HHC unit in the Arun valley.
基金The research was sponsored bythe keyresearch project entitled"Seismic Safety Evaluation and Structural Earthquake Resistance"under the 10th Five-Year Program of the ChinaEarthquake Administration the Joint Earthquake Science Foundation of China (0101302) Contribution number :2005A001 ,the Institute of Crustal Dynamics ,CEA.
文摘Segmentation of the thrust fault zone is a basic problem for earthquake hazard evaluation. The Yingjing-Mabian-Yanjin thrust fault zone is an important seismic belt NW-trending in the southeast margin of the Qinghal-Xizang （Tibet） plateau. The longitudinal faults in the thrust zone are mainly of the thrust slipping type. The late Quaternary motion modes and displacement rates are quite different from north to south. Investigation on valleys across the fault shows that the transverse faults are mainly of dextral strike-slipping type with a bit dip displacement. Based on their connections with the longitudinal faults, three types of transverse faults are generalized, namely： the separate fault, the transform fault and the tear fault, and their functions in the segmentation of the thrust fault zone are compared. As the result, the Yingjing-Mabian-Yanjin thrust fault zone is divided into three segments, and earthquakes occurring in these three segments are compared. The tri-section of the Yingjing-Mabian-Yanjin thrust fault zone identified by transverse fault types reflects, on the one hand, the differences in slip rate, earthquake magnitude and pace from each segment, and the coherence of earthquake rupturing pace on the other hand. It demonstrates that the transverse faults control the segmentation to a certain degree, and each type of the transverse faults plays a different role.
基金supported by MLTM of Korean Government Program 20052004 to S.Kwon
文摘The map expression of ＂abrupt＂ changes in lateral stratigraphic level of a thrust fault has been traditionally interpreted to be a result of the presence of （1） a lateral （or oblique） thrust-ramp, or （2） a frontal ramp with displacement gradient, and/or （3） a combination of these geometries. These geometries have been used to interpret the structures near transverse zones in fold-thrust belts （FTB）. This contribution outlines an alternative explanation that can result in the same map pattern by lateral variations in stratigraphy along the strike of a low angle thrust fault. We describe the natural example of the Leamington transverse zone, which marks the southern margin of the Pennsylvanian-Permian Oquirrh basin with genetically related lateral stratigraphic variations in the North American Sevier FTB. Thus, the observed map pattern at this zone is closely related to lateral stratigraphic variations along the strike of a horizontal fault. Even though the present-day erosional level shows the map pattern that could be interpreted as a lateral ramp, the observed structures along the Leamington zone most likely share the effects of the presence of a lateral （or oblique） ramp, lateral stratigraphic variations along the fault trace, and the displacement gradient.
基金supported by the Western-Caucasus Research Center
文摘The main aim of this research is to get a better knowledge and understanding of the micro-scale oscillatory networks behavior in the solid propellants reactionary zones. Fundamental understanding of the micro-and nano-scale combustion mechanisms is essential to the development and further improvement of the next-generation technologies for extreme control of the solid propellant thrust. Both experiments and theory confirm that the micro-and nano-scale oscillatory networks excitation in the solid propellants reactionary zones is a rather universal phenomenon. In accordance with our concept,the micro-and nano-scale structures form both the fractal and self-organized wave patterns in the solid propellants reactionary zones. Control by the shape, the sizes and spacial orientation of the wave patterns allows manipulate by the energy exchange and release in the reactionary zones. A novel strategy for enhanced extreme thrust control in solid propulsion systems are based on manipulation by selforganization of the micro-and nano-scale oscillatory networks and self-organized patterns formation in the reactionary zones with use of the system of acoustic waves and electro-magnetic fields, generated by special kind of ring-shaped electric discharges along with resonance laser radiation. Application of special kind of the ring-shaped electric discharges demands the minimum expenses of energy and opens prospects for almost inertia-free control by combustion processes. Nano-sized additives will enhance self-organizing and self-synchronization of the micro-and nano-scale oscillatory networks on the nanometer scale. Suggested novel strategy opens the door for completely new ways for enhanced extreme thrust control of the solid propulsion systems.
基金financially supportedby National Science Council.
文摘A contact zone sandwiched between an arc and an oceanic crust was discoveredin the Laohushan area in the present study. It consists of a series of north-dipping imbricatedthrust sheets and is exposed on the surface as a narrow arcuate belt, which extends for about 30 kmin an E-W direction and measures about 1-3 km wide. Lithologically, it can be divided into foursubzones. Subzone 1 consists of meta-andesite and metasandstone; subzone 2, psammitic schists;subzone 3, psammitic and pelitic schists, quartz diorite and hornfelses; and subzone 4, metagabbro,epidote amphibolite and pelitic schists. The metamorphism has the following grading sequence: lowgreenschist facies in subzone 1 - > high greenschist facies in subzone 2 - > low amphibolite fadesin subzone 3 - > epidote amphibolite facies in subzone 4. Petrographic and geochemical evidenceshows that rocks in subzones 1, 2 and 3 are arc rocks, whereas those of subzone 4 are oceaniccrustal rocks. The metamorphic mineral assemblages and especially mineral chemistry of the bluishgreen amphibole from the pelitic schists and epidote amphibolite of subzone 4 suggest that the rocksof the contact zone were metamorphosed at a pressure of up to 0.69 GPa. It is thought that theLate-Mid Ordovician oceanic lithosphere of a back-arc basin was underthrust northerly beneath an arcto a depth of 20-23 km, where the basaltic rocks and gabbro were converted to epidote amphiboliteand metagabbro respectively. Then, the root rocks of the arc and these metamorphosed oceanic rockswere brought up to shallower depths by thrust faults to form a contact zone between the arc and theoceanic crust in the Laohushan area.
基金support from:National Natural Science Foundation of China (Grant no.40672143,40472107,40172076)National Major Fundamental Research and Development Project (Grant no.2005CB422107,G1999043305)+1 种基金Development Foundation of Key Laboratory for Hydrocarbon Accumulation of Education Ministry (Grant no.2003-01)Project of Southern Exploration and Development Division Company,SINOPEC (2003-04).
文摘Field investigation and seismic section explanation showed that the Longmen Mountain Thrust Belt has obvious differential deformation： zonation, segmentation and stratification. Zonation means that, from NW to NE, the Longmen Mountain Thrust Belt can be divided into the Songpan- Garz~ Tectonic Belt, ductile deformation belt, base involved thrust belt, frontal fold-thrust belt, and foreland depression. Segmentation means that it can be divided into five segments from north to south： the northern segment, the Anxian Transfer Zone, the center segment, the Guanxian Transfer Zone and the southern segment. Stratification means that the detachment layers partition the structural styles in profile. The detachment layers in the Longmen Mountain Thrust Belt can be classified into three categories： the deep-level detachment layers, including the crust-mantle system detachment layer, intracrustal detachment layer, and Presinian system basal detachment layer; the middle-level detachment layers, including Cambrian-Ordovician detachment layer, Silurian detachment layer, etc.; and shallow-level detachment layers, including Upper Triassic Xujiahe Formation detachment layer and the Jurassic detachment layers. The multi-level detachment layers have a very important effect on the shaping and evolution of Longmen Mountain Thrust Belt.
文摘Abstract The nearly E-W-trending Aqqikkudug-Weiya zone, more than 1000 km long and about 30 km wide, is an important segment in the Central Asian tectonic framework. It is distributed along the northern margin of the Central Tianshan belt in Xinjiang, NW China and is composed of mylonitized Early Palaeozoic greywacke, volcanic rocks, ophiolitic blocks as a mélange complex, HP/LT-type bleuschist blocks and mylonitized Neoproterozoic schist, gneiss and orthogneiss. Nearly vertical mylonitic foliation and sub-horizontal stretching lineation define its strike-slip feature; various kinematic indicators, such as asymmetric folds, non-coaxial asymmetric macro- to micro-structures and C-axis fabrics of quartz grains of mylonites, suggest that it is a dextral strike-slip ductile shear zone oriented in a nearly E-W direction characterized by “flower” strusture with thrusting or extruding across the zone toward the two sides and upright folds with gently plunging hinges. The Aqqikkudug-Weiya zone experienced at least two stages of ductile shear tectonic evolution: Early Palaeozoic north vergent thrusting ductile shear and Late Carboniferous-Early Permian strike-slip deformation. The strike-slip ductile shear likely took place during Late Palaeozoic time, dated at 269±5 Ma by the40Ar/39Ar analysis on neo-muscovites. The strike-slip deformation was followed by the Hercynian violent S-type granitic magmatism. Geodynamical analysis suggests that the large-scale dextral strike-slip ductile shearing is likely the result of intracontinental adjustment deformation after the collision of the Siberian continental plate towards the northern margin of the Tarim continental plate during the Late Carboniferous. The Himalayan tectonism locally deformed the zone, marked by final uplift, brittle layer-slip and step-type thrust faults, transcurrent faults and E-W-elongated Mesozoic-Cenozoic basins.
文摘Accommodation of continental convergence by crustal thickening and lateral transport is mainly featured as strike-slip faulting along the trends roughly orthogonai to the orientation of plate convergence. This style of faulting will affect seismicity of the involving areas which can be proved in low seismic zones by determining regional stress pattern using numerical methods. Accordingly, the stress distribution and deformation pattern of the South Sanandaj-Sirjan zone in the northeastern part of the Iranian-Arabian collision zone is investigated here using a three dimen-sional mechanical model. The modeled area is bounded between the Zagros thrust fault on the west and Dehshir-Baft fault in the east. The model is composed of three layers： the upper two layers represent the upper brittle and lower ductile crust of the collided continent and the lowest layer represents the lithospheric mantle. The upper crust behaves as an elastic material while the lower crust is considered as a non-Newtonian viscous fluid layer. The lithospheric mantle is taken as a low-viscosity material which is not allowed to move in any direction relative to the overlying layers. The Zagros thrust fault was treated with two different dip values saying 90° and 45° but Dehshir-Baft fault was modeled as a vertical fault and allowed to have a dextral movement regarding to the existing evidence. The driving mechanism applied to the western side of the model was chosen considering two different approaches including a kinematic approach （the Arabian-Eurasian convergence velocity; 35 mm/yr） and a dynamic approach （an external boundary force equal to 3.55E＋17 N）. The resulted stress field indicates an orogen-parallel component of right lateral shear along the Zagros fault implying a rotational deformation pattern within the modeled region that suggests a stress partitioning in the study area. The pattern also indicates a stress accumulation towards the south which could be a reason for the regional seismic quiescence between the two seismic Zagros thrust and Dehshir-Baft faults. Based on the present modeling results, it seems that high stress localization on the boundary faults can be a support of block structure approach or quasi-rigid blocks deformation within the study area. The resultant patterns of stress and displacement fields are generally totally comparable with plate boundary shear zones and have been proven by field data.
