The subduction channel is defined as a planar to wedge-like area of variable size,internal structure and composition,which forms between the upper and lower plates during slab subduction into the mantle.The materials ...The subduction channel is defined as a planar to wedge-like area of variable size,internal structure and composition,which forms between the upper and lower plates during slab subduction into the mantle.The materials in the channel may experience complex pressure,temperature,stress and strain evolution,as well as strong fluid and melt activity.A certain amount of these materials may subduct to and later exhume from>100 km depth,forming high to ultra-high pressure rocks on the surface as widely discovered in nature.Rock deformation in the channel is strongly assisted by metamorphic fluids activities,which change composition and mechanical properties of rocks and thus affect their subduction and exhumation histories.In this study,we investigate the detailed structure and dynamics of both oceanic and continental subduction channels,by conducting highresolution petrological-thermomechanical numerical simulations taking into account fluid and melt activities.The numerical results demonstrate that subduction channels are composed of a tectonic rock melange formed by crustal rocks detached from the subducting slab and the hydrated mantle rocks scratched from the overriding plate.These rocks may either extrude sub-vertically upward through the mantle wedge to the crust of the upper plate,or exhume along the subduction channel to the surface near the suture zone.Based on our numerical results,we first analyze similarities and differences between oceanic and continental subduction channels.We further compare numerical models with and without fluid and melt activity and demonstrate that this activity results in strong weakening and deformation of overriding lithosphere.Finally,we show that fast convergence of orogens subjected to fluid and melt activity leads to strong deformation of the overriding lithosphere and the topography builds up mainly on the overriding plate.In contrast,slow convergence of such orogens leads to very limited deformation of the overriding lithosphere and the mountain building mainly occurs on the s展开更多
Inertial navigation represents a unique method of navigation,in which there is no dependency on external sources of information.As opposed to other position fixing navigation techniques,inertial navigation performs th...Inertial navigation represents a unique method of navigation,in which there is no dependency on external sources of information.As opposed to other position fixing navigation techniques,inertial navigation performs the navigation in a relative sense with respect to the initial navigation state of the moving platform.Hence,inertial navigation systems are not prone to jamming,or spoofing.Inertial navigation systems have developed vastly,from their occurrence in the 1940s up to date.The accuracy of the inertial sensors has improved over time,making inertial sensors sufficient in terms of size,weight,cost,and accuracy for navigation and guidance applications.Within the past few years,inertial sensors have developed from being purely mechanical into incorporating various technologies and taking advantage of numerous physical phenomena,from which the dynamic forces exerted on a moving body could be computed accurately.Besides,the evolution of inertial navigation scheme involved the evolution from stable-platform inertial navigation system,which were mechanically complicated,to computationally demanding strap-down inertial navigation systems.Optical sensory technologies have provided highly accurate inertial sensors,at smaller sizes.Besides,the vibratory inertial navigation technologies enabled the production of Micro-electro-machined inertial sensors that are extremely low-cost,and offer extremely low size,weight and power consumption,making them suitable for a wide range of day-to-day navigation applications.Recently,advanced inertial sensor technologies have been introduced to the industry such as nuclear magnetic resonance technology,coldatom technology,and the reintroduction of fluid-based inertial sensors.On another note,inertial sensor errors constitute a huge research aspect in which it is intended for inertial sensors to reach level in which they could operate for substantially long operation times in the absence of updates from aiding sensors,which would be a huge leap.Inertial sensors error modeling technique展开更多
Fluid flow is an integral part of hydrothermal mineralization, and its analysis and characterization constitute an important part of a mineralization model. The hydrodynamic study of mineralization deals with analyzin...Fluid flow is an integral part of hydrothermal mineralization, and its analysis and characterization constitute an important part of a mineralization model. The hydrodynamic study of mineralization deals with analyzing the driving forces, fluid pressure regimes, fluid flow rate and direction, and their relationships with localization of mineralization. This paper reviews the principles and methods of hydrodynamic studies of mineralization, and discusses their significance and limitations for ore deposit studies and mineral exploration. The driving forces of fluid flow may be related to fluid overpressure, topographic relief, tectonic deformation, and fluid density change due to heating or salinity variation, depending on specific geologic environments and mineralization processes. The study methods may be classified into three types, megascopic （field） observations, microscopic analyses, and numerical modeling. Megascopic features indicative of significantly overpressured （especially lithostatic or supralithostatic） fluid systems include horizontal veins, sand injection dikes, and hydraulic breccias. Microscopic studies, especially microthermometry of fluid inclusions and combined stress analysis and microthermometry of fluid inclusion planes （FIPs） can provide important information about fluid temperature, pressure, and fluid-structural relationships, thus constraining fluid flow models. Numerical modeling can be carried out to solve partial differential equations governing fluid flow, heat transfer, rock deformation and chemical reactions, in order to simulate the distribution of fluid pressure, temperature, fluid flow rate and direction, and mineral precipitation or dissolution in 2D or 3D space and through time. The results of hydrodynamic studies of mineralization can enhance our understanding of the formation nrocesses of hvdrothermal denosits, and can be used directly or indirectly in mineral exnloration.展开更多
The Ordos Basin of North China is not only an important uranium mineralization province, but also a major producer of oil, gas and coal in China. The genetic relationship between uranium mineralization and hydrocarbon...The Ordos Basin of North China is not only an important uranium mineralization province, but also a major producer of oil, gas and coal in China. The genetic relationship between uranium mineralization and hydrocarbons has been recognized by a number of previous studies, but it has not been well understood in terms of the hydrodynamics of basin fluid flow. We have demonstrated in a previous study that the preferential localization of Cretaceous uranium mineralization in the upper part of the Ordos Jurassic section may have been related to the interface between an upward flowing, reducing fluid and a downward flowing, oxidizing fluid. This interface may have been controlled by the interplay between fluid overpressure related to disequilibrium sediment compaction and which drove the upward flow, and topographic relief, which drove the downward flow. In this study, we carried out numerical modeling for the contribution of oil and gas generation to the development of fluid overpressure, in addition to sedi- ment compaction and heating. Our results indicate that when hydrocarbon generation is taken into account, fluid overpressure during the Cretaceous was more than doubled in comparison with the simu- lation when hydrocarbon generation was not considered. Furthermore, fluid overpressure dissipation at the end of sedimentation slowed down relative to the no-hydrocarbon generation case. These results suggest that hydrocarbon generation may have played an important role in uranium mineralization, not only in providing reducing agents required for the mineralization, but also in contributing to the driving force to maintain the upward flow.展开更多
基金supported by the National Basic Research Program of China(Grant No.2015CB856106)the National Natural Science Foundation of China(Grant Nos.41304071,41425010)+2 种基金China Geological Survey Project(Grant No.12120114057301)the start-up research fund from the Institute of Geology of CAGSthe National‘Qian-Ren’Program for young scholars to ZHLI
文摘The subduction channel is defined as a planar to wedge-like area of variable size,internal structure and composition,which forms between the upper and lower plates during slab subduction into the mantle.The materials in the channel may experience complex pressure,temperature,stress and strain evolution,as well as strong fluid and melt activity.A certain amount of these materials may subduct to and later exhume from>100 km depth,forming high to ultra-high pressure rocks on the surface as widely discovered in nature.Rock deformation in the channel is strongly assisted by metamorphic fluids activities,which change composition and mechanical properties of rocks and thus affect their subduction and exhumation histories.In this study,we investigate the detailed structure and dynamics of both oceanic and continental subduction channels,by conducting highresolution petrological-thermomechanical numerical simulations taking into account fluid and melt activities.The numerical results demonstrate that subduction channels are composed of a tectonic rock melange formed by crustal rocks detached from the subducting slab and the hydrated mantle rocks scratched from the overriding plate.These rocks may either extrude sub-vertically upward through the mantle wedge to the crust of the upper plate,or exhume along the subduction channel to the surface near the suture zone.Based on our numerical results,we first analyze similarities and differences between oceanic and continental subduction channels.We further compare numerical models with and without fluid and melt activity and demonstrate that this activity results in strong weakening and deformation of overriding lithosphere.Finally,we show that fast convergence of orogens subjected to fluid and melt activity leads to strong deformation of the overriding lithosphere and the topography builds up mainly on the overriding plate.In contrast,slow convergence of such orogens leads to very limited deformation of the overriding lithosphere and the mountain building mainly occurs on the s
基金Dr.Naser El-Sheimy research funds from NSERC and Canada Research Chairs programs(Grant No.RT691875).
文摘Inertial navigation represents a unique method of navigation,in which there is no dependency on external sources of information.As opposed to other position fixing navigation techniques,inertial navigation performs the navigation in a relative sense with respect to the initial navigation state of the moving platform.Hence,inertial navigation systems are not prone to jamming,or spoofing.Inertial navigation systems have developed vastly,from their occurrence in the 1940s up to date.The accuracy of the inertial sensors has improved over time,making inertial sensors sufficient in terms of size,weight,cost,and accuracy for navigation and guidance applications.Within the past few years,inertial sensors have developed from being purely mechanical into incorporating various technologies and taking advantage of numerous physical phenomena,from which the dynamic forces exerted on a moving body could be computed accurately.Besides,the evolution of inertial navigation scheme involved the evolution from stable-platform inertial navigation system,which were mechanically complicated,to computationally demanding strap-down inertial navigation systems.Optical sensory technologies have provided highly accurate inertial sensors,at smaller sizes.Besides,the vibratory inertial navigation technologies enabled the production of Micro-electro-machined inertial sensors that are extremely low-cost,and offer extremely low size,weight and power consumption,making them suitable for a wide range of day-to-day navigation applications.Recently,advanced inertial sensor technologies have been introduced to the industry such as nuclear magnetic resonance technology,coldatom technology,and the reintroduction of fluid-based inertial sensors.On another note,inertial sensor errors constitute a huge research aspect in which it is intended for inertial sensors to reach level in which they could operate for substantially long operation times in the absence of updates from aiding sensors,which would be a huge leap.Inertial sensors error modeling technique
基金supported by an NSERC-Discovery grant to Chi.Additional supports came from NSFC(41072069, 40772061 and 40930423)State Basic Research Plan (2009CB421005)+1 种基金IRT(0755) 111 Plan(B07011)
文摘Fluid flow is an integral part of hydrothermal mineralization, and its analysis and characterization constitute an important part of a mineralization model. The hydrodynamic study of mineralization deals with analyzing the driving forces, fluid pressure regimes, fluid flow rate and direction, and their relationships with localization of mineralization. This paper reviews the principles and methods of hydrodynamic studies of mineralization, and discusses their significance and limitations for ore deposit studies and mineral exploration. The driving forces of fluid flow may be related to fluid overpressure, topographic relief, tectonic deformation, and fluid density change due to heating or salinity variation, depending on specific geologic environments and mineralization processes. The study methods may be classified into three types, megascopic （field） observations, microscopic analyses, and numerical modeling. Megascopic features indicative of significantly overpressured （especially lithostatic or supralithostatic） fluid systems include horizontal veins, sand injection dikes, and hydraulic breccias. Microscopic studies, especially microthermometry of fluid inclusions and combined stress analysis and microthermometry of fluid inclusion planes （FIPs） can provide important information about fluid temperature, pressure, and fluid-structural relationships, thus constraining fluid flow models. Numerical modeling can be carried out to solve partial differential equations governing fluid flow, heat transfer, rock deformation and chemical reactions, in order to simulate the distribution of fluid pressure, temperature, fluid flow rate and direction, and mineral precipitation or dissolution in 2D or 3D space and through time. The results of hydrodynamic studies of mineralization can enhance our understanding of the formation nrocesses of hvdrothermal denosits, and can be used directly or indirectly in mineral exnloration.
基金supported by NSFC(41072069,40772061 and 40930423)State Basic Research Plan(2009CB421005)+1 种基金IRT (0755)111 Plan(B07011)
文摘The Ordos Basin of North China is not only an important uranium mineralization province, but also a major producer of oil, gas and coal in China. The genetic relationship between uranium mineralization and hydrocarbons has been recognized by a number of previous studies, but it has not been well understood in terms of the hydrodynamics of basin fluid flow. We have demonstrated in a previous study that the preferential localization of Cretaceous uranium mineralization in the upper part of the Ordos Jurassic section may have been related to the interface between an upward flowing, reducing fluid and a downward flowing, oxidizing fluid. This interface may have been controlled by the interplay between fluid overpressure related to disequilibrium sediment compaction and which drove the upward flow, and topographic relief, which drove the downward flow. In this study, we carried out numerical modeling for the contribution of oil and gas generation to the development of fluid overpressure, in addition to sedi- ment compaction and heating. Our results indicate that when hydrocarbon generation is taken into account, fluid overpressure during the Cretaceous was more than doubled in comparison with the simu- lation when hydrocarbon generation was not considered. Furthermore, fluid overpressure dissipation at the end of sedimentation slowed down relative to the no-hydrocarbon generation case. These results suggest that hydrocarbon generation may have played an important role in uranium mineralization, not only in providing reducing agents required for the mineralization, but also in contributing to the driving force to maintain the upward flow.
