The article Extension Set and Non-compatible Problems was published in 1983. It proclaimed the birth of extension theory. Its objects of study are contradictory problems in the realistic world; its theoretical pillars...The article Extension Set and Non-compatible Problems was published in 1983. It proclaimed the birth of extension theory. Its objects of study are contradictory problems in the realistic world; its theoretical pillars are matter element theory and extension set theory. Its basic methods are extension methods. Its practical methods are extension engineering methods,展开更多
Crustal recycling at convergent plate boundaries is essential to mantle heterogeneity.However,crustal signatures in the mantle source of basaltic rocks above subduction zones were primarily incorporated in the form of...Crustal recycling at convergent plate boundaries is essential to mantle heterogeneity.However,crustal signatures in the mantle source of basaltic rocks above subduction zones were primarily incorporated in the form of liquid rather than solid phases.The physicochemical property of liquid phases is determined by the dehydration behavior of crustal rocks at the slab-mantle interface in subduction channels.Because of the significant fractionation in incompatible trace elements but the full inheritance in radiogenic isotopes relative to their crustal sources,the production of liquid phases is crucial to the geochemical transfer from the subducting crust into the mantle.In this process,the stability of specific minerals in subducting crustal rocks exerts a primary control on the enrichment of given trace elements in the liquid phases.For this reason,geochemically enriched oceanic basalts can be categorized into two types in terms of their trace element distribution patterns in the primitive mantle-normalized diagram.One is island arc basalts(IAB),showing enrichment in LILE,Pb and LREE but depletion in HFSE such as Nb and Ta relative to HREE,The other is ocean island basalts(OIB),exhibiting enrichment in LILE and LREE,enrichment or non-depletion in HFSE but depletion in Pb relative to HREE.In either types,these basalts show the enhanced enrichment of LILE and LREE with increasing their incompatibility relative to normal mid-ocean ridge basalts(MORB).The thermal regime of subduction zones can be categorized into two stages in both time and space,The first stage is characterized by compressional tectonism at low thermal gradients.As a consequence,metamorphic dehydration of the subducting crust prevails at forearc to subarc depths due to the breakdown of hydrous minerals such as mica and amphibole in the stability field of garnet and rutile,resulting in the liberation of aqueous solutions with the trace element composition that is considerably enriched in LILE,Pb and LREE but depleted in HFSE and HREE relative to normal M展开更多
The goal of this review paper is to provide a summary of selected discrete element and hybrid finitediscrete element modeling techniques that have emerged in the field of rock mechanics as simulation tools for fractur...The goal of this review paper is to provide a summary of selected discrete element and hybrid finitediscrete element modeling techniques that have emerged in the field of rock mechanics as simulation tools for fracturing processes in rocks and rock masses. The fundamental principles of each computer code are illustrated with particular emphasis on the approach specifically adopted to simulate fracture nucleation and propagation and to account for the presence of rock mass discontinuities. This description is accompanied by a brief review of application studies focusing on laboratory-scale models of rock failure processes and on the simulation of damage development around underground excavations.展开更多
The metavolcanic rocks of greenschist fades developed at Heigouxia Valley in the Mian-Lue tectonic zone, South Qinling orogenic belt is a bimodal volcanic series. It is composed of K-poor, Na-rich tholeiite and dacite...The metavolcanic rocks of greenschist fades developed at Heigouxia Valley in the Mian-Lue tectonic zone, South Qinling orogenic belt is a bimodal volcanic series. It is composed of K-poor, Na-rich tholeiite and dacite-rhyolite. The trace elements characteristics with flat REE pattern of these tholeiites are similar to those of MORB. The Sm-Nd whole rock isochron age of(242±21) Ma and Rb-Sr whole rock isochron age of (221±13) Ma of this metavolcanic series consistently indicate their rnetamorphic time. Their relatively high initial εNd value of +6.1 at the rnetamorphic age (242 Ma) suggest that the volcanic rocks were derived from a depleted MORB type mantle source. Their trace elements and Nd isotope compositions suggest an oceanic basin developed from a rift on the continental margin of the Yangtze Block during the late Paleozoic and closed in the Triassic, This is the first case clearly showing the existence of relict of late Paleozoic oceanic crust in Fast Qinling belt, which provides important evidence for the Mian-Lue tectonic zone as a structure zone.展开更多
文摘The article Extension Set and Non-compatible Problems was published in 1983. It proclaimed the birth of extension theory. Its objects of study are contradictory problems in the realistic world; its theoretical pillars are matter element theory and extension set theory. Its basic methods are extension methods. Its practical methods are extension engineering methods,
基金supported by funds from the Chinese Academy of Sciences(XDB18020303)the Chinese Ministry of Science and Technology(2015CB856100)the National Natural ScienceFoundation of China(41590620)
文摘Crustal recycling at convergent plate boundaries is essential to mantle heterogeneity.However,crustal signatures in the mantle source of basaltic rocks above subduction zones were primarily incorporated in the form of liquid rather than solid phases.The physicochemical property of liquid phases is determined by the dehydration behavior of crustal rocks at the slab-mantle interface in subduction channels.Because of the significant fractionation in incompatible trace elements but the full inheritance in radiogenic isotopes relative to their crustal sources,the production of liquid phases is crucial to the geochemical transfer from the subducting crust into the mantle.In this process,the stability of specific minerals in subducting crustal rocks exerts a primary control on the enrichment of given trace elements in the liquid phases.For this reason,geochemically enriched oceanic basalts can be categorized into two types in terms of their trace element distribution patterns in the primitive mantle-normalized diagram.One is island arc basalts(IAB),showing enrichment in LILE,Pb and LREE but depletion in HFSE such as Nb and Ta relative to HREE,The other is ocean island basalts(OIB),exhibiting enrichment in LILE and LREE,enrichment or non-depletion in HFSE but depletion in Pb relative to HREE.In either types,these basalts show the enhanced enrichment of LILE and LREE with increasing their incompatibility relative to normal mid-ocean ridge basalts(MORB).The thermal regime of subduction zones can be categorized into two stages in both time and space,The first stage is characterized by compressional tectonism at low thermal gradients.As a consequence,metamorphic dehydration of the subducting crust prevails at forearc to subarc depths due to the breakdown of hydrous minerals such as mica and amphibole in the stability field of garnet and rutile,resulting in the liberation of aqueous solutions with the trace element composition that is considerably enriched in LILE,Pb and LREE but depleted in HFSE and HREE relative to normal M
文摘The goal of this review paper is to provide a summary of selected discrete element and hybrid finitediscrete element modeling techniques that have emerged in the field of rock mechanics as simulation tools for fracturing processes in rocks and rock masses. The fundamental principles of each computer code are illustrated with particular emphasis on the approach specifically adopted to simulate fracture nucleation and propagation and to account for the presence of rock mass discontinuities. This description is accompanied by a brief review of application studies focusing on laboratory-scale models of rock failure processes and on the simulation of damage development around underground excavations.
基金Project supported by the National Natural Science Foundation of China.
文摘The metavolcanic rocks of greenschist fades developed at Heigouxia Valley in the Mian-Lue tectonic zone, South Qinling orogenic belt is a bimodal volcanic series. It is composed of K-poor, Na-rich tholeiite and dacite-rhyolite. The trace elements characteristics with flat REE pattern of these tholeiites are similar to those of MORB. The Sm-Nd whole rock isochron age of(242±21) Ma and Rb-Sr whole rock isochron age of (221±13) Ma of this metavolcanic series consistently indicate their rnetamorphic time. Their relatively high initial εNd value of +6.1 at the rnetamorphic age (242 Ma) suggest that the volcanic rocks were derived from a depleted MORB type mantle source. Their trace elements and Nd isotope compositions suggest an oceanic basin developed from a rift on the continental margin of the Yangtze Block during the late Paleozoic and closed in the Triassic, This is the first case clearly showing the existence of relict of late Paleozoic oceanic crust in Fast Qinling belt, which provides important evidence for the Mian-Lue tectonic zone as a structure zone.
