Metamorphic mechanism has the advantages of variable topology and variable degrees of freedom, which can realize the requirements of multi-conditions and multi-tasks, and has a good application prospect. The configura...Metamorphic mechanism has the advantages of variable topology and variable degrees of freedom, which can realize the requirements of multi-conditions and multi-tasks, and has a good application prospect. The configuration transformation is prominent feature of the metamorphic mechanism. The number of constraints or properties of the kinematic pairs provided by the metamorphic kinematic pairs will change under certain conditions, its dynamic performance is much more complex than that of traditional kinematic pairs with immutable constraints. However, the clearance model about traditional kinematic pairs with immutable constraints established by long-term research is difficult to be directly applied to the metachromatic kinematic pairs. Referring to the experience of the traditional kinematic pairs with immutable constraints, the continuous contact model of Metamorphic Groove pin pair with clearance is established. According to the traditional continuous contact model of the kinematic pairs with immutable constraints, the forces between the elements of kinematic pair of the mechanism with clearance and the ideal mechanism without clearance are regarded as the same, and the inertia force and inertia moment of the components are also calculated according to the acceleration of the ideal mechanism. The clearance is regarded as a massless virtual bar with length r. For the rotating pair part, the massless virtual bar length r is the difference between the radius of the shaft and the hole, and for the sliding pair part, the massless virtual bar length r is half of the difference between the height of the slider and the guide groove. According to the new mechanism without gap after adding the imaginary bar, kinetic energy and potential energy of the system are calculated for the two configurations of mechanism with metamorphic Groove pin pair with clearance. The kinetic energy and potential energy of the system are calculated according to the new mechanism without clearance after adding the massless virtual bar. The kinetic energy, potential energy and generalized force are substituted into the Lagrangian equation to obtain the motion equation of the metamorphic mechanism, which lays the foundation for the dynamic performance study of the mechanism with metamorphic groove pin pair with clearance.展开更多
Research into metamorphism plays a pivotal role in reconstructing the evolution of continent,particularly through the study of ancient rocks that are highly susceptible to metamorphic alterations due to multiple tecto...Research into metamorphism plays a pivotal role in reconstructing the evolution of continent,particularly through the study of ancient rocks that are highly susceptible to metamorphic alterations due to multiple tectonic activities.In the big data era,the establishment of new data platforms and the application of big data methods have become a focus for metamorphic rocks.Significant progress has been made in creating specialized databases,compiling comprehensive datasets,and utilizing data analytics to address complex scientific questions.However,many existing databases are inadequate in meeting the specific requirements of metamorphic research,resulting from a substantial amount of valuable data remaining uncollected.Therefore,constructing new databases that can cope with the development of the data era is necessary.This article provides an extensive review of existing databases related to metamorphic rocks and discusses data-driven studies in this.Accordingly,several crucial factors that need to be taken into consideration in the establishment of specialized metamorphic databases are identified,aiming to leverage data-driven applications to achieve broader scientific objectives in metamorphic research.展开更多
The Heilongjiang Complex in northeast China(NE China)separates the Jiamusi and Songliao blocks and marks the suture zone of the former Mudanjiang Ocean,as evidenced by a variety of oceanic basalt-derived blueschists.U...The Heilongjiang Complex in northeast China(NE China)separates the Jiamusi and Songliao blocks and marks the suture zone of the former Mudanjiang Ocean,as evidenced by a variety of oceanic basalt-derived blueschists.Understanding the closure history of the Mudanjiang Ocean is crucial to unravelling the tectonic transition from the final amalgamation of the Central Asian Orogenic Belt(CAOB)to the onset of the Paleo-Pacific subduction.In this study,we investigate epidote-ferroglaucophane(Ep-Fgl)and garnet-ferrobarroisite(Grt-Fbrs)schists from the Yilan area of the Heilongjiang Complex through petrological,mineralogical,thermodynamic modelling,whole-rock geochemical,and geochronological analyses.The Ep-Fgl schists preserve a peak assemblage of ferroglaucophane+epidote+chlorite+clinopyroxene+phengite+titanite with peak P-T conditions of 13.5-15.8 kbar and 458-495℃.On the other hand,the Grt-Fbrs schists exhibit a peak assemblage of garnet+glaucophane/ferroglaucophane+lawsonite+chlorite+phengite+rutile±clinopyroxene±titanite,deriving peak P-T conditions of 16.4-18.3 kbar and 457-475℃.Both types of schist record similar clockwise P-T paths,with three metamorphic stages:a peak epidote-to-lawsonite blueschist-facies stage,a post-peak decompression stage in the epidote amphibolite-facies,and a late greenschist-facies overprint stage.The Ep-Fgl schists display alkaline OIB-like geochemical affinities,while the Grt-Fbrs schists show tholeiitic MORB-like characteristics,suggesting that the protoliths represent fragments of the Mudanjiang oceanic crust.Magmatic zircon grains from Ep-Fgl schists yield protolith ages of 276±1 Ma and 280±1 Ma,whereas zircon of Grt-Fbrs schists document protolith ages of 249±2 Ma and 248±2 Ma,indicating that the Mudanjiang Ocean existed since at least the early Permian.Reconstruction of the metamorphic P-T evolution,combined with previous magmatic and metamorphic age data from rocks of the Heilongjiang Complex and of adjacent tectonic units suggests that the subduction and eventual closure of the Mudanjiang Ocean occurred between the late Triassic and middle Jurassic,driven by a regional stress regime shift caused by the westward subduction of the Paleo-Pacific Plate beneath Eurasia.展开更多
The Yishui complex,located in the western Shandong area of the North China Craton,is representative of the Archean crystalline basement of the North China Craton to explore the early tectonic-thermal evolution history...The Yishui complex,located in the western Shandong area of the North China Craton,is representative of the Archean crystalline basement of the North China Craton to explore the early tectonic-thermal evolution history of the Earth.Detailed petrography,mineral chemistry,metamorphic evolution and zircon U-Pb dating are presented for felsic granulite and two-pyroxene granulite from the Yishui complex to contribute to new insights into the Neoarchean tectonic evolution of the North China Craton.Three mineral assemblages are recognized for these granulite samples,including the prograde(M1),peak(M2)and retrograde(M3)mineral assemblages.Conventional geothermobarometry and phase equilibrium modeling yield P-T conditions of 6.5-10.9 kbar/718-839℃ for the peak metamorphism,which define a medium-pressure granulite-facies metamorphism occurred at middle to lower crust.Anticlockwise P-T paths with near-isobaric cooling(IBC)retrograde segments were reconstructed.Zircon LA-ICP-MS U-Pb dating suggests that the protolith of the felsic granulite was emplaced at 2541±7 Ma and the subsequent medium-pressure granulite-facies metamorphism occurred at 2518-2494 Ma.A two-stage mantle plume related crustal-scale sagduction geodynamic regime is proposed in the western Shandong terrane in the Neoarchean.展开更多
The stratum lithology and geological structure of the highway tunnel in the mountainous areas of western China are complex,and the engineering geological conditions are complicated.When the highway tunnel passes throu...The stratum lithology and geological structure of the highway tunnel in the mountainous areas of western China are complex,and the engineering geological conditions are complicated.When the highway tunnel passes through different lithological strata,its structural design and construction technology are completely diff erent.Therefore,in order to support the tunnel design and construction,the tunnel survey Among them,the identification of the contact boundary between magmatic rock and metamorphic rock and the grade of surrounding rock is very important.Through magnetotelluric survey of the Mupi tunnel of Jiuzhaigou-Mianyang highway on G8513 line,2D forward numerical simulation,1D,2D,3D inversion,and engineering geological analysis,it is revealed that the electrical characteristics of each layer,focusing on the identification of the contact boundary between magmatic rock and metamorphic rock.This study provides the electrical characteristics of the magmatic rock and metamorphic rock contact boundary of the Mupi Tunnel.It is speculated that the boundary is revealed by the tunnel construction excavation,which verifies the correctness of the geophysical inversion model and provides a more detailed design basis for the tunnel design.I believe that taking the Mupi Tunnel survey as an example,through this research,it can provide detailed geophysical evidence for highway tunnels to distinguish between magmatic rock and metamorphic rock.展开更多
The intricate relationship between origami and mechanism underscores the fertile ground for innovation,which is particularly evident in the construction theory of thick-panel origami.Despite its potential,thick panel ...The intricate relationship between origami and mechanism underscores the fertile ground for innovation,which is particularly evident in the construction theory of thick-panel origami.Despite its potential,thick panel origami remains relatively unexplored in the context of single-loop metamorphic mechanisms.Drawing inspiration from thickpanel origami,particularly Miura origami,this study proposes a pioneering single-loop 6R multiple metamorphic mechanism.Through rigorous mathematical modeling(including the construction and resolution of the D-H closed-loop equation)and leveraging advanced analytical tools such as the screw theory and Lie theory,this study meticulously elucidates the planar,spherical,and Bennett motion branches of the mechanism.Furthermore,it delineates all the three bifurcation points between the motion branches,thereby providing a comprehensive understanding of the kinematic behavior of the mechanism.A metamorphic network can be constructed by applying several single-loop mechanisms to a symmetrical layout.Owing to its metamorphic properties,this network can act as a structural backbone for deployable antennas,aerospace shelters,and morphing wing units,thereby enabling a single mechanism to achieve multiple folding configurations.This paper not only introduces innovative metamorphic mechanisms but also suggests a promising method for uncovering and designing metamorphic mechanisms by developing new mechanisms from thick-panel origami.展开更多
Current research on reconfigurable parallel mechanisms(RPMs)primarily focuses on achieving limited configuration changes,while mechanisms capable of extensive mode switching with distinct motion branches remain challe...Current research on reconfigurable parallel mechanisms(RPMs)primarily focuses on achieving limited configuration changes,while mechanisms capable of extensive mode switching with distinct motion branches remain challenging to design.Conventional kinematotropic chains offer limited reconfigurability,underscoring the need for novel designs that enable broader operational adaptability.In this research,a novel diamond-like chain(DLC)with metamorphic units is proposed developed from generalized diamond kinematotropic chains.By altering the axes of the metamorphic units,the DLC realizes three distinct configurations,each corresponding to one of five motion branches characterized by bifurcation and metamorphic transitions.This DLC serves as the fundamental building block for constructing a reconfigurable hybrid limb.Using screw theory,the constraint properties of the limb in its five phases are analyzed and classified into three types:unconstrained limbs,limbs applying constraint forces,and limbs applying constraint couples.Based on this analysis,a RPM consisting of three reconfigurable limbs is developed.Its reconfigurability stems from the inherent bifurcation and metamorphic capabilities of the DLC-based limbs.This research introduces a RPM capable of controlled switching among ten distinct motion modes,with mobility ranging from three to six degrees of freedom.The proposed mechanism demonstrates high versatility and practical feasibility,offering a promising solution for applications requiring variable motion characteristics and adaptive performance.展开更多
Some metamorphic relations （MR） are not good at detecting faults in metamorphic testing. In this paper, the method of making compositional MR （CMR） based on the speculative law of proposition logic is presented. T...Some metamorphic relations （MR） are not good at detecting faults in metamorphic testing. In this paper, the method of making compositional MR （CMR） based on the speculative law of proposition logic is presented. This method constructs new MRs by composing existing MRs in a pairwise way. Because CMR contains all the advantages of the MRs that form it, its fault detection performance is wonderful. On the other hand, the number of relations will decrease greatly after composing, so a program can be tested with much fewer test cases when CMRs are used. In order to research the characteristics of a CMR, two case studies are analyzed. The experimental results show that the CMR＇s performance is mostly determined by the central MRs forming it and the sequence of composition. Testing efficiency is improved greatly when CMRs are used.展开更多
During the 1:50000 regional geological survey in Jimo,east Shandong Province,Paleoproterozoic metamorphic supracrustal rocks and Neoproterozoic metamorphic plutonite were newly discovered.These rocks displayed inclusi...During the 1:50000 regional geological survey in Jimo,east Shandong Province,Paleoproterozoic metamorphic supracrustal rocks and Neoproterozoic metamorphic plutonite were newly discovered.These rocks displayed inclusions which had occurred in the Mesozoic granite,and the main lithologies are schist,granulite,marble,and granitic gneiss.Geochemical analyses suggest that Neoproterozoic metamorphic plutonite are characterized by high-K,metaluminous to weakly peraluminous.They are enriched in LILE and depleted in HFSE,with moderately enrichment of LREE,weak fractionation of LREE from HREE and negative Eu anomalies.The surface age of plutonic rocks in the survey area is 770.2±2.4 Ma,representing the age of magma crystallization,which is agreement with the the Neoproterozoic magmatic event after Rodinia supercontinent in the northern margin of Southern China continental block.In addition,the age of sporadic distribution(298 Ma and 269 Ma)is mixed zircon age,representing the rocks experienced metamorphism in Indosinian period.According to the associated mineral assemblages,and the characteristic metamorphic minerals and temperature pressure conditions,four metamorphic facies were identified,including amphibolitic,epidote amphibolite,greenschist,and mid-high pressure greenschist.Analysis of tectonic setting suggests that granitic gneiss is formed in an extensional environment and was involved from the continental margin magmatic arc to intraplate environment.Jimo is distributed in the east of Zhuwu fault,and has the same Spatial distribution location with the Weihai uplift UHP metamorphic belt rocks.The metamorphic rocks in Jimo area have similar geochemical characteristics of elements,tectonic setting and retrograde metamorphism with that in the Sulu UHP metamorphic belt.Therefore,Zhuwu fault may be the boundary fault of Sulu UHP metamorphic belt.展开更多
As a type of multiconfiguration mechanism that can operate in an under-actuated state,metamorphic mechanisms were proposed more than two decades ago and attracted significant interest.Studies on structural synthesis o...As a type of multiconfiguration mechanism that can operate in an under-actuated state,metamorphic mechanisms were proposed more than two decades ago and attracted significant interest.Studies on structural synthesis of metamorphic mechanisms tend to focus more on metamorphic techniques and the structural synthesis of source mechanisms for metamorphic mechanisms.By designing different constraint architectures of metamorphic joints,multistructures can be obtained from the same source metamorphic mechanism.To determine the constraint architectures of metamorphic joints and their different assembly combinations,a kinematic status matrix and a corresponding constraint status matrix are constructed based on the metamorphic cyclogram of a source mechanism.According to the equivalent resistance gradient model and the constraint status matrix,an equivalent resistance matrix for the metamorphic joints is proposed.A structural synthesis matrix of the metamorphic mechanism is then obtained from the equivalent resistance matrix by deducing the constraint form vectors of the metamorphic joints.Furthermore,a kinematic diagram synthesis of the source metamorphic mechanism of a planar single-loop metamorphic mechanism is proposed,which is based on only the 14 one-or zero-degrees-of-freedom linkage groups.The entire structural design method of a metamorphic mechanism is based on the structural synthesis matrix and is presented as a systematic process.Finally,the proposed structural design approach is illustrated by two examples to verify its feasibility and practicality.This study provides an effective method for designing a practical multi-mobility and multiconfiguration planar single-loop metamorphic mechanism with a single actuator.展开更多
In order to obtain a simple way for the force analysis of metamorphic mechanisms, the systematic method to unify the force analysis approach of metamorphic mechanisms as that of conventional planar mechanisms is propo...In order to obtain a simple way for the force analysis of metamorphic mechanisms, the systematic method to unify the force analysis approach of metamorphic mechanisms as that of conventional planar mechanisms is proposed. A force analysis method of metamorphic mechanisms is developed by transforming the augmented Assur groups into Assur groups, so that the force analysis problem of metamorphic mechanisms is converted into the force analysis problems of conventional planar mechanisms. The constraint force change rules and values of metamorphic joints are obtained by the proposed method, and the constraint force analysis equations of revolute metamorphic joints in augmented Assur group RRRR and prismatic metamorphic joints in augmented Assur group RRPR are deduced. The constraint force analysis is illustrated by the constrained spring force design of paper folding metamorphic mechanism, and its metamorphic working process is controlled by the spring force and geometric constraints of metamorphic joints. The results of spring force show that developped design method and approach are feasible and practical. By transforming augmented Assur groups into Assur groups, a new method for the constraint force analysis of metamorphic joints is proposed firstly to provide the basis for dynamic analysis of metamorphic mechanism.展开更多
Ontogeny and metamorphic. development of female reproductive organs in Ephedra sinica Stapf were surveyed. At the end of April, female cones began to initialize from the vegetative buds. Pollination occurred in mid-Ma...Ontogeny and metamorphic. development of female reproductive organs in Ephedra sinica Stapf were surveyed. At the end of April, female cones began to initialize from the vegetative buds. Pollination occurred in mid-May and seeds matured at the beginning of July. The ontogenetic pattern of female reproductive organs of E. sin ca is basically similar to that of E. distachya L. The foliar nature of the outer envelope of the ovule in Ephedra is corroborated. Reduction of ovule number as a tendency of speciation in the genus is substantiated by the occurrence of tri-ovulate cones coupled with comprehensive characters of the genus. The metamorphic patterns as well as the leaf nature of the outer envelope indicate that female cones of Ephedra are compound while the female reproductive units of the ovulate cone have been reduced from secondary reproductive shoots similar to those of cordaites by phylogenetic transformation, fusion and reduction. Each fertile bract together with its axillary female reproductive unit composed the Bract Scale and Seed Scale Complex of Ephedra.展开更多
The Dabie metamorphic terrane is tectonically located within the intersection area of the WNW trending east Qinling orogenic belt with the NNE trending west Pacific domain. The Punctuated multistage convergent movemen...The Dabie metamorphic terrane is tectonically located within the intersection area of the WNW trending east Qinling orogenic belt with the NNE trending west Pacific domain. The Punctuated multistage convergent movement and the emplacemeat of YanShanian granitoid intrusions account for the complication of its tectonic framework. The Dabie metamorphic complex is composed of 3 units: supracrustals of early Precambrian age, granite gneiss and metamorphic magic rocks of lats Precambrian age. Three major metsmorphic Stages can be traced, i. e. granulite factes, amphibolite facies of Precambrian and the HP/ LT epidote amphibolite and greenschist facies of Phanerozoic. The Hong'an Group underlying the Dabie complex shows epidote amphibolite facies which is probably synchronous with the amphibolite facies of the Dabie complex. The Protolith of the HP and UHP eclogiter are diversided. The amphibole, epidote and other mineral inclusions within the eclogite minerals testify to the earlier history of Pre-eclogitic metamorphism. The peak metamorphic assemblage coesite-omphacite-garnet is superimposed by amphibolite, epidote amphibolite and greenschist facies of retrograde metamorphism. In many regions the eclogites appear as pods, lenses and layers within ductile shear zones having synkinematic greenschist or epidote amphibolite facies of retrograde metamorphism. The Sm-Nd isochron of whole rock and garnet combined with Ph-Ph dating of zircon crystals from Mifengjian eclogite block in Hubei suggest that the UHI, metamorphism probably took Place nearly 480 Ma Which evideoces one of the most important tertono-thermal events of the punctuated evolution in the Dabie terrane.展开更多
Taking the Paleogene Shahejie Formation in Nanpu sag of Bohai Bay Basin as an example,this study comprehensively utilizes seismic,mud logging,well logging,physical property analysis and core thin section data to inves...Taking the Paleogene Shahejie Formation in Nanpu sag of Bohai Bay Basin as an example,this study comprehensively utilizes seismic,mud logging,well logging,physical property analysis and core thin section data to investigate the metamorphic reservoir formed by contact metamorphism after igneous rock intrusion.(1)A geological model of the igneous intrusion contact met amorphic system is proposed,which can be divided into five structural layers vertically:the intrusion,upper metamorphic aureole,lower metamorphic aureole,normal sedimentary layers on the roof and floor.(2)The intrusion is characterized by xenoliths indicating intrusive facies at the top,regular changes in rock texture and mineral crystallization from the center to the edge on a microscopic scale,and low-angle oblique penetrations of the intrusion through sedimentary strata on a macroscopic scale.The metamorphic aureole has characteristics such as sedimentary rocks as the host rock,typical palimpsest textures developed,various low-temperature thermal metamorphic minerals developed,and medium-low grade thermal metamorphic rocks as the lithology.(3)The reservoir in contact metamorphic aureole has two types of reservoir spaces:matrix pores and fractures.The matrix pores are secondary"intergranular pores"distributed around metamorphic minerals after thermal metamorphic transformation in metasandstones.The fractures are mainly structural fractures and intrusive compressive fractures in metamudstones.The reservoirs generally have three spatial distribution characteristics:layered,porphyritic and hydrocarbon impregnation along fracture.(4)The distribution of reservoirs in the metamorphic aureole is mainly controlled by the intensity of thermal baking.Furthermore,the distribution of favorable reservoirs is controlled by the coupling of favorable lithofacies and thermal contact metamorphism,intrusive compression and hydrothermal dissolution.The proposal and application of the geological model of the intrusion contact metamorphic system are expected to promote the discovery of exploration targets of contact metamorphic rock in Nanpu sag,and provide a reference for the study and exploration of deep contact metamorphic rock reservoirs in the Bohai Bay Basin.展开更多
The process and path of retrometamorphism of coesite have great significance to our understanding of the P-T tracks of the exhumation of ultrahigh-pressure metamorphic rocks. Most of the coesites in the eclogite from ...The process and path of retrometamorphism of coesite have great significance to our understanding of the P-T tracks of the exhumation of ultrahigh-pressure metamorphic rocks. Most of the coesites in the eclogite from Shima, Anhui Province, the Dabie Mountains, China, are found degraded to quartz partly or wholly, with ruptures occurring in the shells, outside which include the coesite and quartz. According to the microscopic observation, the sample of coesite inclusion is composed of garnet, quartz and coesite, based on which we have built a three-shelled composite sphere model to compute the transition of coesite. Based on the crystal growth formulas and pressure conditions of the ruptures in the garnet, we have calculated the radius of the quartz sphere, which depends on temperature, and eventually drawn the different retrometamorphic paths for different retrometamorphism rates.展开更多
The application of metamorphic testing(MT)on automatic program repair(APR-MT)is used to generate a patch without test oracles by examining whether the input metamorphic relation(MR)is satisfied or not.However,the deli...The application of metamorphic testing(MT)on automatic program repair(APR-MT)is used to generate a patch without test oracles by examining whether the input metamorphic relation(MR)is satisfied or not.However,the delivered patch is plausible since it may satisfy the input MR but violate other MRs.This inspires us to propose an improved approach to enhance the effectiveness of APR-MT with metamorphic relation group.Ourapproach involves three major steps.First,we formally define the repair process of APR-MT by building the model of automatic program repair and metamorphic testing separately.Then,we propose the advanced model of automatic program repair based on metamorphic relation group,named METARO^(3),which takes several MRs as input while only one MR is used in APR-MT.We additionally present two kinds of selection strategies to rank MRs in descending order of the fault detection capability,which helps shorten the repair time of finding a patch.To demonstrate the feasibility and procedure of our approach,an illustration example was conducted.The results show that METARO^(3) can improve the effectiveness of APR-MT significantly.展开更多
Abstract There are two extensional systems in the Xiaoqinling metamorphic core complex (XMCC). One is the detachment fault system developed along the peripheries of the XMCC, which extended in an ESE-WNW direction and...Abstract There are two extensional systems in the Xiaoqinling metamorphic core complex (XMCC). One is the detachment fault system developed along the peripheries of the XMCC, which extended in an ESE-WNW direction and whose upper plate moved towards the WNW. The other extensional system includes the retrograde shear zones and normal faults developed within the XMCC, which represent the collapse of the XMCC. Ar-Ar and K-Ar dating shows that the extension of the detachment fault system continued from 135 to 123 Ma, i.e. in the late stage of its evolution at about 127 Ma. The collapse represented by the extensional system within the XMCC was operative during 120–106 Ma, and its main activity occurred about 116 Ma ago. These suggest that the XMCC experienced two extensional stages in its evolution, i.e., the syn-orogenic regional extension and post-orogenic collapse extension.展开更多
: The kinematic vorticity number and strain of the mylonitic zone related to the detachment fault increase from ESE to WNW along the moving direction of the upper plate of the Xiaoqinling metamorphic core complex (XMC...: The kinematic vorticity number and strain of the mylonitic zone related to the detachment fault increase from ESE to WNW along the moving direction of the upper plate of the Xiaoqinling metamorphic core complex (XMCC) and the geometry of quartz c-axis fabrics changes progressively from crossed girdles to single girdles in the same direction. Therefore, pure shear is dominant in the ESE part of the XMCC while simple shear becomes increasingly important towards WNW. However, the shear type does not change with the strain across the shear zone, thus the variation of shear type is of significance in indicating the formation mechanism. The granitic plutons within the XMCC came from the deep source and their emplacement was an active and forceful upwelling prior to the detachment faulting. The PTt path demonstrates that magmatism is an important cause for the formation of the XMCC. The formation mechanism of the XMCC is supposed to be active plutonism and passive detachment. Crustal thickening and magmatic doming caused necking extension with pure shear, and magmatic heating and doming resulted in detachment extension with simple shear and formed the XMCC.展开更多
The Louzidian metamorphic core complex (LMCC) in southern Chifeng is located on the northern margin of the North China craton. Structural analyses of the LMCC and its extensional detachment system indicate that the LM...The Louzidian metamorphic core complex (LMCC) in southern Chifeng is located on the northern margin of the North China craton. Structural analyses of the LMCC and its extensional detachment system indicate that the LMCC experienced two-stage extension. The ductile regime experienced top-to-northeast shearing extension and the brittle detachment fault underwent top-down-outwards slipping. Between these two stages, a semi-ductile regime recorded the transition from ductile to brittle. The hanging wall of the detachment fault is similar to those classic supradetachment basins in western North America. Analyses of provenance and paleocurrent directions in the basins show that there were two filling stages. In the early stage, materials came from the southwest margin of the basin and the hanging wall of the detachment system and were transported from southwest to northeast; while in the late stage, deposits were derived from the footwall of the detachment fault and transported outwards to the two sides of the core complex. Since the filling period of the basins is from the late Jurassic to the late Cretaceous and it is coeval with the extension, the two filling stages reflect the two-stage history of the detachment fault. The large-scale late Jurassic underplating in the deep crust of the Chifeng area led to thickening and heating of the middle-upper crust and trigged the extension at depths and volcanism on the surface. In the early Cretaceous the upper plate of the detachment fault moved northeastwards and sediments were transported from southwest to northeast, while in the late Cretaceous the core complex was uplifted rapidly, the original basin was separated by the uplifted core, and lower-plate-derived debris was deposited in the adjacent upper-plate basins of the detachment fault. Evidentially, the development of the supradetachment basins were controlled by the extension and in turn the fillings in the basins recorded information of the extension, which has provided new evidence for kinematic interpretation of the Louzidian core complex.展开更多
The present-day observable tectonic framework of the ultrahigh-pressure (UHP) and high-pressure (HP) metamorphic belts in the Dabie-Sulu region was dominantly formed by an extensional process, mostly between 200 and 1...The present-day observable tectonic framework of the ultrahigh-pressure (UHP) and high-pressure (HP) metamorphic belts in the Dabie-Sulu region was dominantly formed by an extensional process, mostly between 200 and 170 Ma, following the Triassic collision between the Sino-Korean and Yangtze cratons. The framework that controls the present spatial distribution of UHP and HP metamorphic rocks in particular displays the typical features of a Cordilleran-type metamorphic core complex, in which at least four regional-scale, shallow-dipping detachment zones are recognized. Each of these detachment zones corresponds to a pressure gap of 0.5 to 2.0 GPa. The detachment zones separate the rocks exposed in the region into several petrotectonic units with different P-T conditions. The geometry and kinematics of both the detachment zones and the petrotectonic units show that the exhumation of UHP and HP metamorphic rocks in the Dabie-Sulu region was achieved, at least in part, by non-coaxial ductile flow in the multi-layered detachment zones, and by coaxial vertical shortening and horizontal stretching in the metamorphic units, under amphibolite- to greenschist-facies conditions, and in an extensional regime. All ductile extensional deformations occurred at depths below 10 to 15 km, i.e. below the brittle/ductile deformation transition.展开更多
文摘Metamorphic mechanism has the advantages of variable topology and variable degrees of freedom, which can realize the requirements of multi-conditions and multi-tasks, and has a good application prospect. The configuration transformation is prominent feature of the metamorphic mechanism. The number of constraints or properties of the kinematic pairs provided by the metamorphic kinematic pairs will change under certain conditions, its dynamic performance is much more complex than that of traditional kinematic pairs with immutable constraints. However, the clearance model about traditional kinematic pairs with immutable constraints established by long-term research is difficult to be directly applied to the metachromatic kinematic pairs. Referring to the experience of the traditional kinematic pairs with immutable constraints, the continuous contact model of Metamorphic Groove pin pair with clearance is established. According to the traditional continuous contact model of the kinematic pairs with immutable constraints, the forces between the elements of kinematic pair of the mechanism with clearance and the ideal mechanism without clearance are regarded as the same, and the inertia force and inertia moment of the components are also calculated according to the acceleration of the ideal mechanism. The clearance is regarded as a massless virtual bar with length r. For the rotating pair part, the massless virtual bar length r is the difference between the radius of the shaft and the hole, and for the sliding pair part, the massless virtual bar length r is half of the difference between the height of the slider and the guide groove. According to the new mechanism without gap after adding the imaginary bar, kinetic energy and potential energy of the system are calculated for the two configurations of mechanism with metamorphic Groove pin pair with clearance. The kinetic energy and potential energy of the system are calculated according to the new mechanism without clearance after adding the massless virtual bar. The kinetic energy, potential energy and generalized force are substituted into the Lagrangian equation to obtain the motion equation of the metamorphic mechanism, which lays the foundation for the dynamic performance study of the mechanism with metamorphic groove pin pair with clearance.
基金funded by the National Natural Science Foundation of China(No.42220104008)。
文摘Research into metamorphism plays a pivotal role in reconstructing the evolution of continent,particularly through the study of ancient rocks that are highly susceptible to metamorphic alterations due to multiple tectonic activities.In the big data era,the establishment of new data platforms and the application of big data methods have become a focus for metamorphic rocks.Significant progress has been made in creating specialized databases,compiling comprehensive datasets,and utilizing data analytics to address complex scientific questions.However,many existing databases are inadequate in meeting the specific requirements of metamorphic research,resulting from a substantial amount of valuable data remaining uncollected.Therefore,constructing new databases that can cope with the development of the data era is necessary.This article provides an extensive review of existing databases related to metamorphic rocks and discusses data-driven studies in this.Accordingly,several crucial factors that need to be taken into consideration in the establishment of specialized metamorphic databases are identified,aiming to leverage data-driven applications to achieve broader scientific objectives in metamorphic research.
基金the support of Yajing Mao and Lingquan Zhao during the preparation of the manuscript.This research was financially supported by the National Natural Science Foundation of China(No.U2244206).
文摘The Heilongjiang Complex in northeast China(NE China)separates the Jiamusi and Songliao blocks and marks the suture zone of the former Mudanjiang Ocean,as evidenced by a variety of oceanic basalt-derived blueschists.Understanding the closure history of the Mudanjiang Ocean is crucial to unravelling the tectonic transition from the final amalgamation of the Central Asian Orogenic Belt(CAOB)to the onset of the Paleo-Pacific subduction.In this study,we investigate epidote-ferroglaucophane(Ep-Fgl)and garnet-ferrobarroisite(Grt-Fbrs)schists from the Yilan area of the Heilongjiang Complex through petrological,mineralogical,thermodynamic modelling,whole-rock geochemical,and geochronological analyses.The Ep-Fgl schists preserve a peak assemblage of ferroglaucophane+epidote+chlorite+clinopyroxene+phengite+titanite with peak P-T conditions of 13.5-15.8 kbar and 458-495℃.On the other hand,the Grt-Fbrs schists exhibit a peak assemblage of garnet+glaucophane/ferroglaucophane+lawsonite+chlorite+phengite+rutile±clinopyroxene±titanite,deriving peak P-T conditions of 16.4-18.3 kbar and 457-475℃.Both types of schist record similar clockwise P-T paths,with three metamorphic stages:a peak epidote-to-lawsonite blueschist-facies stage,a post-peak decompression stage in the epidote amphibolite-facies,and a late greenschist-facies overprint stage.The Ep-Fgl schists display alkaline OIB-like geochemical affinities,while the Grt-Fbrs schists show tholeiitic MORB-like characteristics,suggesting that the protoliths represent fragments of the Mudanjiang oceanic crust.Magmatic zircon grains from Ep-Fgl schists yield protolith ages of 276±1 Ma and 280±1 Ma,whereas zircon of Grt-Fbrs schists document protolith ages of 249±2 Ma and 248±2 Ma,indicating that the Mudanjiang Ocean existed since at least the early Permian.Reconstruction of the metamorphic P-T evolution,combined with previous magmatic and metamorphic age data from rocks of the Heilongjiang Complex and of adjacent tectonic units suggests that the subduction and eventual closure of the Mudanjiang Ocean occurred between the late Triassic and middle Jurassic,driven by a regional stress regime shift caused by the westward subduction of the Paleo-Pacific Plate beneath Eurasia.
基金supported by the Natural Science Foundation of Shandong Provence(Grant No.ZR2023MD058)National Natural Science Foundation of China(Grant Nos.42072219,41802201)。
文摘The Yishui complex,located in the western Shandong area of the North China Craton,is representative of the Archean crystalline basement of the North China Craton to explore the early tectonic-thermal evolution history of the Earth.Detailed petrography,mineral chemistry,metamorphic evolution and zircon U-Pb dating are presented for felsic granulite and two-pyroxene granulite from the Yishui complex to contribute to new insights into the Neoarchean tectonic evolution of the North China Craton.Three mineral assemblages are recognized for these granulite samples,including the prograde(M1),peak(M2)and retrograde(M3)mineral assemblages.Conventional geothermobarometry and phase equilibrium modeling yield P-T conditions of 6.5-10.9 kbar/718-839℃ for the peak metamorphism,which define a medium-pressure granulite-facies metamorphism occurred at middle to lower crust.Anticlockwise P-T paths with near-isobaric cooling(IBC)retrograde segments were reconstructed.Zircon LA-ICP-MS U-Pb dating suggests that the protolith of the felsic granulite was emplaced at 2541±7 Ma and the subsequent medium-pressure granulite-facies metamorphism occurred at 2518-2494 Ma.A two-stage mantle plume related crustal-scale sagduction geodynamic regime is proposed in the western Shandong terrane in the Neoarchean.
基金National Natural Science Foundation of China(41630640)National Science Foundation of Innovation Research Group(41521002)+1 种基金National Natural Science Foundation of China(41790445)Construction S&T Project of Department of Transportation of Sichuan Province(Grant No.2020A01).
文摘The stratum lithology and geological structure of the highway tunnel in the mountainous areas of western China are complex,and the engineering geological conditions are complicated.When the highway tunnel passes through different lithological strata,its structural design and construction technology are completely diff erent.Therefore,in order to support the tunnel design and construction,the tunnel survey Among them,the identification of the contact boundary between magmatic rock and metamorphic rock and the grade of surrounding rock is very important.Through magnetotelluric survey of the Mupi tunnel of Jiuzhaigou-Mianyang highway on G8513 line,2D forward numerical simulation,1D,2D,3D inversion,and engineering geological analysis,it is revealed that the electrical characteristics of each layer,focusing on the identification of the contact boundary between magmatic rock and metamorphic rock.This study provides the electrical characteristics of the magmatic rock and metamorphic rock contact boundary of the Mupi Tunnel.It is speculated that the boundary is revealed by the tunnel construction excavation,which verifies the correctness of the geophysical inversion model and provides a more detailed design basis for the tunnel design.I believe that taking the Mupi Tunnel survey as an example,through this research,it can provide detailed geophysical evidence for highway tunnels to distinguish between magmatic rock and metamorphic rock.
基金Supported by National Natural Science Foundation of China(Grant Nos.52192634,52305015,52335003)Guangdong Basic and Applied Basic Research Foundation(Grant No.2023A1515011268)Science and Technology Innovation Committee of Shenzhen(Grant Nos.GXWD20231129102029003,KQTD20210811090146075).
文摘The intricate relationship between origami and mechanism underscores the fertile ground for innovation,which is particularly evident in the construction theory of thick-panel origami.Despite its potential,thick panel origami remains relatively unexplored in the context of single-loop metamorphic mechanisms.Drawing inspiration from thickpanel origami,particularly Miura origami,this study proposes a pioneering single-loop 6R multiple metamorphic mechanism.Through rigorous mathematical modeling(including the construction and resolution of the D-H closed-loop equation)and leveraging advanced analytical tools such as the screw theory and Lie theory,this study meticulously elucidates the planar,spherical,and Bennett motion branches of the mechanism.Furthermore,it delineates all the three bifurcation points between the motion branches,thereby providing a comprehensive understanding of the kinematic behavior of the mechanism.A metamorphic network can be constructed by applying several single-loop mechanisms to a symmetrical layout.Owing to its metamorphic properties,this network can act as a structural backbone for deployable antennas,aerospace shelters,and morphing wing units,thereby enabling a single mechanism to achieve multiple folding configurations.This paper not only introduces innovative metamorphic mechanisms but also suggests a promising method for uncovering and designing metamorphic mechanisms by developing new mechanisms from thick-panel origami.
基金Supported by National Natural Science Foundation of China(Grant No.52175019)Beijing Municipal Natural Science Foundation(Grant Nos.L222038,20240484699)+1 种基金Joint Funds of Industry-university-research of Shanghai Academy of Spaceflight Technology(Grant No.SAST2022-017)Beijing Municipal Key Laboratory of Space-ground Interconnection and Convergence of China and Key Laboratory of IoT Monitoring and Early Warning,Ministry of Emergency Management,Project‘Vice President of Science and Technology’of Changping District,Beijing.
文摘Current research on reconfigurable parallel mechanisms(RPMs)primarily focuses on achieving limited configuration changes,while mechanisms capable of extensive mode switching with distinct motion branches remain challenging to design.Conventional kinematotropic chains offer limited reconfigurability,underscoring the need for novel designs that enable broader operational adaptability.In this research,a novel diamond-like chain(DLC)with metamorphic units is proposed developed from generalized diamond kinematotropic chains.By altering the axes of the metamorphic units,the DLC realizes three distinct configurations,each corresponding to one of five motion branches characterized by bifurcation and metamorphic transitions.This DLC serves as the fundamental building block for constructing a reconfigurable hybrid limb.Using screw theory,the constraint properties of the limb in its five phases are analyzed and classified into three types:unconstrained limbs,limbs applying constraint forces,and limbs applying constraint couples.Based on this analysis,a RPM consisting of three reconfigurable limbs is developed.Its reconfigurability stems from the inherent bifurcation and metamorphic capabilities of the DLC-based limbs.This research introduces a RPM capable of controlled switching among ten distinct motion modes,with mobility ranging from three to six degrees of freedom.The proposed mechanism demonstrates high versatility and practical feasibility,offering a promising solution for applications requiring variable motion characteristics and adaptive performance.
基金The National Natural Science Foundation of China(No.60425206,60633010,60773104,60503033)the Excellent Talent Foundation of Teaching and Research of Southeast University
文摘Some metamorphic relations （MR） are not good at detecting faults in metamorphic testing. In this paper, the method of making compositional MR （CMR） based on the speculative law of proposition logic is presented. This method constructs new MRs by composing existing MRs in a pairwise way. Because CMR contains all the advantages of the MRs that form it, its fault detection performance is wonderful. On the other hand, the number of relations will decrease greatly after composing, so a program can be tested with much fewer test cases when CMRs are used. In order to research the characteristics of a CMR, two case studies are analyzed. The experimental results show that the CMR＇s performance is mostly determined by the central MRs forming it and the sequence of composition. Testing efficiency is improved greatly when CMRs are used.
基金funded by Natural Science Foundation of China(41502064)Natural Science Foundation of Shandong Province(ZR2015JL016)+2 种基金Land and resources survey project of China Geological Survey(1212011120749)the National Geological Survey Project(1212010811029)the Scientific Research Foundation of Shandong University of Science and Technology(2014RCJJ012)
文摘During the 1:50000 regional geological survey in Jimo,east Shandong Province,Paleoproterozoic metamorphic supracrustal rocks and Neoproterozoic metamorphic plutonite were newly discovered.These rocks displayed inclusions which had occurred in the Mesozoic granite,and the main lithologies are schist,granulite,marble,and granitic gneiss.Geochemical analyses suggest that Neoproterozoic metamorphic plutonite are characterized by high-K,metaluminous to weakly peraluminous.They are enriched in LILE and depleted in HFSE,with moderately enrichment of LREE,weak fractionation of LREE from HREE and negative Eu anomalies.The surface age of plutonic rocks in the survey area is 770.2±2.4 Ma,representing the age of magma crystallization,which is agreement with the the Neoproterozoic magmatic event after Rodinia supercontinent in the northern margin of Southern China continental block.In addition,the age of sporadic distribution(298 Ma and 269 Ma)is mixed zircon age,representing the rocks experienced metamorphism in Indosinian period.According to the associated mineral assemblages,and the characteristic metamorphic minerals and temperature pressure conditions,four metamorphic facies were identified,including amphibolitic,epidote amphibolite,greenschist,and mid-high pressure greenschist.Analysis of tectonic setting suggests that granitic gneiss is formed in an extensional environment and was involved from the continental margin magmatic arc to intraplate environment.Jimo is distributed in the east of Zhuwu fault,and has the same Spatial distribution location with the Weihai uplift UHP metamorphic belt rocks.The metamorphic rocks in Jimo area have similar geochemical characteristics of elements,tectonic setting and retrograde metamorphism with that in the Sulu UHP metamorphic belt.Therefore,Zhuwu fault may be the boundary fault of Sulu UHP metamorphic belt.
基金Supported by National Natural Science Foundation of China(Grant No.51575091,51205052)Aeronautical Science Foundation of China(Grant No.20170250001)the Basic Science and Research Project of Chinese National University(Grant No.N160304008).
文摘As a type of multiconfiguration mechanism that can operate in an under-actuated state,metamorphic mechanisms were proposed more than two decades ago and attracted significant interest.Studies on structural synthesis of metamorphic mechanisms tend to focus more on metamorphic techniques and the structural synthesis of source mechanisms for metamorphic mechanisms.By designing different constraint architectures of metamorphic joints,multistructures can be obtained from the same source metamorphic mechanism.To determine the constraint architectures of metamorphic joints and their different assembly combinations,a kinematic status matrix and a corresponding constraint status matrix are constructed based on the metamorphic cyclogram of a source mechanism.According to the equivalent resistance gradient model and the constraint status matrix,an equivalent resistance matrix for the metamorphic joints is proposed.A structural synthesis matrix of the metamorphic mechanism is then obtained from the equivalent resistance matrix by deducing the constraint form vectors of the metamorphic joints.Furthermore,a kinematic diagram synthesis of the source metamorphic mechanism of a planar single-loop metamorphic mechanism is proposed,which is based on only the 14 one-or zero-degrees-of-freedom linkage groups.The entire structural design method of a metamorphic mechanism is based on the structural synthesis matrix and is presented as a systematic process.Finally,the proposed structural design approach is illustrated by two examples to verify its feasibility and practicality.This study provides an effective method for designing a practical multi-mobility and multiconfiguration planar single-loop metamorphic mechanism with a single actuator.
基金Supported by National Natural Science Foundation of China(Grant Nos.51175069,51205052)State Key Laboratory of Robotics of China(Grant No.2012-O16)Basic Science and Research Project of Chinese National University,China(Grant No.N140304004)
文摘In order to obtain a simple way for the force analysis of metamorphic mechanisms, the systematic method to unify the force analysis approach of metamorphic mechanisms as that of conventional planar mechanisms is proposed. A force analysis method of metamorphic mechanisms is developed by transforming the augmented Assur groups into Assur groups, so that the force analysis problem of metamorphic mechanisms is converted into the force analysis problems of conventional planar mechanisms. The constraint force change rules and values of metamorphic joints are obtained by the proposed method, and the constraint force analysis equations of revolute metamorphic joints in augmented Assur group RRRR and prismatic metamorphic joints in augmented Assur group RRPR are deduced. The constraint force analysis is illustrated by the constrained spring force design of paper folding metamorphic mechanism, and its metamorphic working process is controlled by the spring force and geometric constraints of metamorphic joints. The results of spring force show that developped design method and approach are feasible and practical. By transforming augmented Assur groups into Assur groups, a new method for the constraint force analysis of metamorphic joints is proposed firstly to provide the basis for dynamic analysis of metamorphic mechanism.
文摘Ontogeny and metamorphic. development of female reproductive organs in Ephedra sinica Stapf were surveyed. At the end of April, female cones began to initialize from the vegetative buds. Pollination occurred in mid-May and seeds matured at the beginning of July. The ontogenetic pattern of female reproductive organs of E. sin ca is basically similar to that of E. distachya L. The foliar nature of the outer envelope of the ovule in Ephedra is corroborated. Reduction of ovule number as a tendency of speciation in the genus is substantiated by the occurrence of tri-ovulate cones coupled with comprehensive characters of the genus. The metamorphic patterns as well as the leaf nature of the outer envelope indicate that female cones of Ephedra are compound while the female reproductive units of the ovulate cone have been reduced from secondary reproductive shoots similar to those of cordaites by phylogenetic transformation, fusion and reduction. Each fertile bract together with its axillary female reproductive unit composed the Bract Scale and Seed Scale Complex of Ephedra.
文摘The Dabie metamorphic terrane is tectonically located within the intersection area of the WNW trending east Qinling orogenic belt with the NNE trending west Pacific domain. The Punctuated multistage convergent movement and the emplacemeat of YanShanian granitoid intrusions account for the complication of its tectonic framework. The Dabie metamorphic complex is composed of 3 units: supracrustals of early Precambrian age, granite gneiss and metamorphic magic rocks of lats Precambrian age. Three major metsmorphic Stages can be traced, i. e. granulite factes, amphibolite facies of Precambrian and the HP/ LT epidote amphibolite and greenschist facies of Phanerozoic. The Hong'an Group underlying the Dabie complex shows epidote amphibolite facies which is probably synchronous with the amphibolite facies of the Dabie complex. The Protolith of the HP and UHP eclogiter are diversided. The amphibole, epidote and other mineral inclusions within the eclogite minerals testify to the earlier history of Pre-eclogitic metamorphism. The peak metamorphic assemblage coesite-omphacite-garnet is superimposed by amphibolite, epidote amphibolite and greenschist facies of retrograde metamorphism. In many regions the eclogites appear as pods, lenses and layers within ductile shear zones having synkinematic greenschist or epidote amphibolite facies of retrograde metamorphism. The Sm-Nd isochron of whole rock and garnet combined with Ph-Ph dating of zircon crystals from Mifengjian eclogite block in Hubei suggest that the UHI, metamorphism probably took Place nearly 480 Ma Which evideoces one of the most important tertono-thermal events of the punctuated evolution in the Dabie terrane.
基金Supported by the Basic Science Research Fund Project of PetroChina Affiliated Institute(2020D-5008-06)。
文摘Taking the Paleogene Shahejie Formation in Nanpu sag of Bohai Bay Basin as an example,this study comprehensively utilizes seismic,mud logging,well logging,physical property analysis and core thin section data to investigate the metamorphic reservoir formed by contact metamorphism after igneous rock intrusion.(1)A geological model of the igneous intrusion contact met amorphic system is proposed,which can be divided into five structural layers vertically:the intrusion,upper metamorphic aureole,lower metamorphic aureole,normal sedimentary layers on the roof and floor.(2)The intrusion is characterized by xenoliths indicating intrusive facies at the top,regular changes in rock texture and mineral crystallization from the center to the edge on a microscopic scale,and low-angle oblique penetrations of the intrusion through sedimentary strata on a macroscopic scale.The metamorphic aureole has characteristics such as sedimentary rocks as the host rock,typical palimpsest textures developed,various low-temperature thermal metamorphic minerals developed,and medium-low grade thermal metamorphic rocks as the lithology.(3)The reservoir in contact metamorphic aureole has two types of reservoir spaces:matrix pores and fractures.The matrix pores are secondary"intergranular pores"distributed around metamorphic minerals after thermal metamorphic transformation in metasandstones.The fractures are mainly structural fractures and intrusive compressive fractures in metamudstones.The reservoirs generally have three spatial distribution characteristics:layered,porphyritic and hydrocarbon impregnation along fracture.(4)The distribution of reservoirs in the metamorphic aureole is mainly controlled by the intensity of thermal baking.Furthermore,the distribution of favorable reservoirs is controlled by the coupling of favorable lithofacies and thermal contact metamorphism,intrusive compression and hydrothermal dissolution.The proposal and application of the geological model of the intrusion contact metamorphic system are expected to promote the discovery of exploration targets of contact metamorphic rock in Nanpu sag,and provide a reference for the study and exploration of deep contact metamorphic rock reservoirs in the Bohai Bay Basin.
基金the National Natural Science Foundation of China grants 40172019 ,40272083 the Natural Science Foundation of HubeiProvince grant 2002AB020.
文摘The process and path of retrometamorphism of coesite have great significance to our understanding of the P-T tracks of the exhumation of ultrahigh-pressure metamorphic rocks. Most of the coesites in the eclogite from Shima, Anhui Province, the Dabie Mountains, China, are found degraded to quartz partly or wholly, with ruptures occurring in the shells, outside which include the coesite and quartz. According to the microscopic observation, the sample of coesite inclusion is composed of garnet, quartz and coesite, based on which we have built a three-shelled composite sphere model to compute the transition of coesite. Based on the crystal growth formulas and pressure conditions of the ruptures in the garnet, we have calculated the radius of the quartz sphere, which depends on temperature, and eventually drawn the different retrometamorphic paths for different retrometamorphism rates.
基金The work was supported by a grant from National Natural Science Foundation of China(No.61772423).
文摘The application of metamorphic testing(MT)on automatic program repair(APR-MT)is used to generate a patch without test oracles by examining whether the input metamorphic relation(MR)is satisfied or not.However,the delivered patch is plausible since it may satisfy the input MR but violate other MRs.This inspires us to propose an improved approach to enhance the effectiveness of APR-MT with metamorphic relation group.Ourapproach involves three major steps.First,we formally define the repair process of APR-MT by building the model of automatic program repair and metamorphic testing separately.Then,we propose the advanced model of automatic program repair based on metamorphic relation group,named METARO^(3),which takes several MRs as input while only one MR is used in APR-MT.We additionally present two kinds of selection strategies to rank MRs in descending order of the fault detection capability,which helps shorten the repair time of finding a patch.To demonstrate the feasibility and procedure of our approach,an illustration example was conducted.The results show that METARO^(3) can improve the effectiveness of APR-MT significantly.
文摘Abstract There are two extensional systems in the Xiaoqinling metamorphic core complex (XMCC). One is the detachment fault system developed along the peripheries of the XMCC, which extended in an ESE-WNW direction and whose upper plate moved towards the WNW. The other extensional system includes the retrograde shear zones and normal faults developed within the XMCC, which represent the collapse of the XMCC. Ar-Ar and K-Ar dating shows that the extension of the detachment fault system continued from 135 to 123 Ma, i.e. in the late stage of its evolution at about 127 Ma. The collapse represented by the extensional system within the XMCC was operative during 120–106 Ma, and its main activity occurred about 116 Ma ago. These suggest that the XMCC experienced two extensional stages in its evolution, i.e., the syn-orogenic regional extension and post-orogenic collapse extension.
文摘: The kinematic vorticity number and strain of the mylonitic zone related to the detachment fault increase from ESE to WNW along the moving direction of the upper plate of the Xiaoqinling metamorphic core complex (XMCC) and the geometry of quartz c-axis fabrics changes progressively from crossed girdles to single girdles in the same direction. Therefore, pure shear is dominant in the ESE part of the XMCC while simple shear becomes increasingly important towards WNW. However, the shear type does not change with the strain across the shear zone, thus the variation of shear type is of significance in indicating the formation mechanism. The granitic plutons within the XMCC came from the deep source and their emplacement was an active and forceful upwelling prior to the detachment faulting. The PTt path demonstrates that magmatism is an important cause for the formation of the XMCC. The formation mechanism of the XMCC is supposed to be active plutonism and passive detachment. Crustal thickening and magmatic doming caused necking extension with pure shear, and magmatic heating and doming resulted in detachment extension with simple shear and formed the XMCC.
基金supported by the National Natural Science Foundation of China(grant 40102017)the Doctoral Program of Higher Education(grant 2000000128).
文摘The Louzidian metamorphic core complex (LMCC) in southern Chifeng is located on the northern margin of the North China craton. Structural analyses of the LMCC and its extensional detachment system indicate that the LMCC experienced two-stage extension. The ductile regime experienced top-to-northeast shearing extension and the brittle detachment fault underwent top-down-outwards slipping. Between these two stages, a semi-ductile regime recorded the transition from ductile to brittle. The hanging wall of the detachment fault is similar to those classic supradetachment basins in western North America. Analyses of provenance and paleocurrent directions in the basins show that there were two filling stages. In the early stage, materials came from the southwest margin of the basin and the hanging wall of the detachment system and were transported from southwest to northeast; while in the late stage, deposits were derived from the footwall of the detachment fault and transported outwards to the two sides of the core complex. Since the filling period of the basins is from the late Jurassic to the late Cretaceous and it is coeval with the extension, the two filling stages reflect the two-stage history of the detachment fault. The large-scale late Jurassic underplating in the deep crust of the Chifeng area led to thickening and heating of the middle-upper crust and trigged the extension at depths and volcanism on the surface. In the early Cretaceous the upper plate of the detachment fault moved northeastwards and sediments were transported from southwest to northeast, while in the late Cretaceous the core complex was uplifted rapidly, the original basin was separated by the uplifted core, and lower-plate-derived debris was deposited in the adjacent upper-plate basins of the detachment fault. Evidentially, the development of the supradetachment basins were controlled by the extension and in turn the fillings in the basins recorded information of the extension, which has provided new evidence for kinematic interpretation of the Louzidian core complex.
基金This study was supported by the Key State Basic Research Development Project grant G1999075506the National Natural Science Foundation of China grants 49794041,49972067 and 49772146the former Ministry of Geology and Mineral Resources Project No.9501102.
文摘The present-day observable tectonic framework of the ultrahigh-pressure (UHP) and high-pressure (HP) metamorphic belts in the Dabie-Sulu region was dominantly formed by an extensional process, mostly between 200 and 170 Ma, following the Triassic collision between the Sino-Korean and Yangtze cratons. The framework that controls the present spatial distribution of UHP and HP metamorphic rocks in particular displays the typical features of a Cordilleran-type metamorphic core complex, in which at least four regional-scale, shallow-dipping detachment zones are recognized. Each of these detachment zones corresponds to a pressure gap of 0.5 to 2.0 GPa. The detachment zones separate the rocks exposed in the region into several petrotectonic units with different P-T conditions. The geometry and kinematics of both the detachment zones and the petrotectonic units show that the exhumation of UHP and HP metamorphic rocks in the Dabie-Sulu region was achieved, at least in part, by non-coaxial ductile flow in the multi-layered detachment zones, and by coaxial vertical shortening and horizontal stretching in the metamorphic units, under amphibolite- to greenschist-facies conditions, and in an extensional regime. All ductile extensional deformations occurred at depths below 10 to 15 km, i.e. below the brittle/ductile deformation transition.
