Identification of the meta-instable stress state and study of its mechanism and evolution of relevant physical fields would be of great significance for determination of potential seismic risks and estimation of criti...Identification of the meta-instable stress state and study of its mechanism and evolution of relevant physical fields would be of great significance for determination of potential seismic risks and estimation of critical times. In laboratory experiments, that the specimen enters the meta-instable is marked by accelerated stress release. Could we use the experimental result to identify the earthquake in natural conditions? Because the observational data from one station can only reflect the stress state beneath this station, the key problem for identification of the meta-instability is how to recognize regional stress state through observational data from many stations. In this work, we choose the evolution of the temperature field over varied deformation stages during a stick-slip event on a 5 bending fault as an example, and attempt to find the response features of the physical quantity when the fault enters the meta-instable state. We discuss the characteristics of stages for the stress build-up, stress-time process deviating from linearity before instability, meta-instability, instability, and post-instability, respectively. The result shows that the fault instability slide is a conversion process from independent activities of each fault segment to synergism activity. The instability implies completion of the synergism. The stage deviating from linearity is the onset of stress release, and it is also the onset of the synergism. At the meta-instability stages, stress release becomes dominant, while the synergism tends to finish. Therefore, the analysis of the regional overall stress state should not start from individual stations, and instead it should begin with the evolution of the whole deformation field.展开更多
The Tainan Basin is one of the set of Cenozoic extensional basins along northern margin of the South China Sea that experienced extension and subsequently thermal subsidence. The Tainan Basin is close to the Taiwan Ar...The Tainan Basin is one of the set of Cenozoic extensional basins along northern margin of the South China Sea that experienced extension and subsequently thermal subsidence. The Tainan Basin is close to the Taiwan Arc-Trench System and straddles a transition zone between oceanic and continental crust. A new regional multi-channel seismic profile （973-01） across the region of NE South China Sea is introduced in this paper. In seismic stratigraphy and structural geology, a model of Cenozoic tectono-sedimentation of the Tainan Basin is established. The results show that three stages can be suggested in Tainan Basin; In Stage A （Oligocene （？）-Lower Miocene） the stratigraphy shows restricted rifting, indicating crustal extension. Terrestrial sedi- ments mostly filled the faulted sags of the North Depression on the continental shelf. Structural highs, including the Central Uplift, blocked material transportation to the South Depression in abyssal basin. In Stage B the Tainan Basin （Middle-Upper Miocene） exhibits a broad subsidence resulting from the post-rifting thermal cooling. The faulted-sags in North Depression had been filled up. Terrestrial materials were transported over the structural highs and deposited directly in the South Depression through sub- marine gullies or canyons. This sedimentation resulted in a crucial change in the slope to a modem shape. In Stage C （Latest Miocene-Recent） a phase change from extension to compression took place due to the orogeny caused by the overthrusting of the Luzon volcanic arc. Many inverse structures, such as thrusts, fault bend folds, and a regional unconformity were formed. Forland basin began developing.展开更多
A preliminary study of b value of rocks with two kinds of structural models has been made on the base of a new acoustic emission recording system. It shows that b value of the sample decreases obviously when the sampl...A preliminary study of b value of rocks with two kinds of structural models has been made on the base of a new acoustic emission recording system. It shows that b value of the sample decreases obviously when the sample with compressive en echelon faults changes into a tensile one after interchange occurs between stress axis σ1 and σ2. A similar experiment is observed when the sample with tensile en echelon faults changes into that with a bend fault after two segments of the en echelon fault linking up. These facts indicate that the variation of b value may con-tain the information of the regional dominant structural model. Therefore, b-value analyses could be a new method for studying regional dominant structural models.展开更多
In the past three decades, molecular magnetism has been a rapidly growing interdisciplinary field in chemistry, phys- ics and materials sciences. It covers diverse range of topics including inorganic/organic/hybrid ma...In the past three decades, molecular magnetism has been a rapidly growing interdisciplinary field in chemistry, phys- ics and materials sciences. It covers diverse range of topics including inorganic/organic/hybrid magnetic molecular ma- terials, multifunctional and/or switchable magnetic molecu- lar materials, molecular nanomagnets, nanostructural mo- lecular magnets, molecular spintronics and biomagnetism. Much research on molecular magnetism has been carried out in China both before and after we organized the Interna- tional Conference on Molecule-Based Magnets 2010 （ICMM 2010） in Beijing.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos. 40872129, 41172180)
文摘Identification of the meta-instable stress state and study of its mechanism and evolution of relevant physical fields would be of great significance for determination of potential seismic risks and estimation of critical times. In laboratory experiments, that the specimen enters the meta-instable is marked by accelerated stress release. Could we use the experimental result to identify the earthquake in natural conditions? Because the observational data from one station can only reflect the stress state beneath this station, the key problem for identification of the meta-instability is how to recognize regional stress state through observational data from many stations. In this work, we choose the evolution of the temperature field over varied deformation stages during a stick-slip event on a 5 bending fault as an example, and attempt to find the response features of the physical quantity when the fault enters the meta-instable state. We discuss the characteristics of stages for the stress build-up, stress-time process deviating from linearity before instability, meta-instability, instability, and post-instability, respectively. The result shows that the fault instability slide is a conversion process from independent activities of each fault segment to synergism activity. The instability implies completion of the synergism. The stage deviating from linearity is the onset of stress release, and it is also the onset of the synergism. At the meta-instability stages, stress release becomes dominant, while the synergism tends to finish. Therefore, the analysis of the regional overall stress state should not start from individual stations, and instead it should begin with the evolution of the whole deformation field.
基金the National Basic Research Program (973)of China (No. 2007CB411704)the National Natural Science Foun-dation of China (No. 40676024)+1 种基金the Key Laboratory of MarginalSea Geologythe Chinese Academy of Sciences (Nos. KZCX3-SW-234 and MSGL0609)
文摘The Tainan Basin is one of the set of Cenozoic extensional basins along northern margin of the South China Sea that experienced extension and subsequently thermal subsidence. The Tainan Basin is close to the Taiwan Arc-Trench System and straddles a transition zone between oceanic and continental crust. A new regional multi-channel seismic profile （973-01） across the region of NE South China Sea is introduced in this paper. In seismic stratigraphy and structural geology, a model of Cenozoic tectono-sedimentation of the Tainan Basin is established. The results show that three stages can be suggested in Tainan Basin; In Stage A （Oligocene （？）-Lower Miocene） the stratigraphy shows restricted rifting, indicating crustal extension. Terrestrial sedi- ments mostly filled the faulted sags of the North Depression on the continental shelf. Structural highs, including the Central Uplift, blocked material transportation to the South Depression in abyssal basin. In Stage B the Tainan Basin （Middle-Upper Miocene） exhibits a broad subsidence resulting from the post-rifting thermal cooling. The faulted-sags in North Depression had been filled up. Terrestrial materials were transported over the structural highs and deposited directly in the South Depression through sub- marine gullies or canyons. This sedimentation resulted in a crucial change in the slope to a modem shape. In Stage C （Latest Miocene-Recent） a phase change from extension to compression took place due to the orogeny caused by the overthrusting of the Luzon volcanic arc. Many inverse structures, such as thrusts, fault bend folds, and a regional unconformity were formed. Forland basin began developing.
基金National Natural Science Foundation of China (Grant No. 40072067) and Minister of Science and Technology of China (2004BA601B01).
文摘A preliminary study of b value of rocks with two kinds of structural models has been made on the base of a new acoustic emission recording system. It shows that b value of the sample decreases obviously when the sample with compressive en echelon faults changes into a tensile one after interchange occurs between stress axis σ1 and σ2. A similar experiment is observed when the sample with tensile en echelon faults changes into that with a bend fault after two segments of the en echelon fault linking up. These facts indicate that the variation of b value may con-tain the information of the regional dominant structural model. Therefore, b-value analyses could be a new method for studying regional dominant structural models.
文摘In the past three decades, molecular magnetism has been a rapidly growing interdisciplinary field in chemistry, phys- ics and materials sciences. It covers diverse range of topics including inorganic/organic/hybrid magnetic molecular ma- terials, multifunctional and/or switchable magnetic molecu- lar materials, molecular nanomagnets, nanostructural mo- lecular magnets, molecular spintronics and biomagnetism. Much research on molecular magnetism has been carried out in China both before and after we organized the Interna- tional Conference on Molecule-Based Magnets 2010 （ICMM 2010） in Beijing.
