To better understand Earth's present tectonic style-plate tectonics—and how it may have evolved from single plate(stagnant lid) tectonics, it is instructive to consider how common it is among similar bodies in th...To better understand Earth's present tectonic style-plate tectonics—and how it may have evolved from single plate(stagnant lid) tectonics, it is instructive to consider how common it is among similar bodies in the Solar System. Plate tectonics is a style of convection for an active planetoid where lid fragment(plate) motions reflect sinking of dense lithosphere in subduction zones, causing upwelling of asthenosphere at divergent plate boundaries and accompanied by focused upwellings, or mantle plumes;any other tectonic style is usefully called "stagnant lid" or "fragmented lid". In 2015 humanity completed a 50+ year effort to survey the 30 largest planets, asteroids, satellites, and inner Kuiper Belt objects,which we informally call "planetoids" and use especially images of these bodies to infer their tectonic activity. The four largest planetoids are enveloped in gas and ice(Jupiter, Saturn, Uranus, and Neptune)and are not considered. The other 26 planetoids range in mass over 5 orders of magnitude and in diameter over 2 orders of magnitude, from massive Earth down to tiny Proteus; these bodies also range widely in density, from 1000 to 5500 kg/m^3. A gap separates 8 silicate planetoids with ρ = 3000 kg/m^3 or greater from 20 icy planetoids(including the gaseous and icy giant planets) with ρ = 2200 kg/m^3 or less. We define the "Tectonic Activity Index"(TAI), scoring each body from 0 to 3 based on evidence for recent volcanism, deformation, and resurfacing(inferred from impact crater density). Nine planetoids with TAI = 2 or greater are interpreted to be tectonically and convectively active whereas 17 with TAI <2 are inferred to be tectonically dead. We further infer that active planetoids have lithospheres or icy shells overlying asthenosphere or water/weak ice. TAI of silicate(rocky) planetoids positively correlates with their inferred Rayleigh number. We conclude that some type of stagnant lid tectonics is the dominant mode of heat loss and that plate tectonics is unusual. To make progress understanding E展开更多
An analytical model is presented to study vertical dynamic response of the ballastless track on long-span plate-truss cable-stayed bridges based on an explicit dynamic analysis method.In the model,the train,ballastles...An analytical model is presented to study vertical dynamic response of the ballastless track on long-span plate-truss cable-stayed bridges based on an explicit dynamic analysis method.In the model,the train,ballastless track and bridge are treated as a coupled vibration system with interaction.By simulating the dynamic process of the system,this paper discusses the distribution law of dynamic responses of the bridge deck and the bed slab.It shows the necessity of a base plate for the ballastless track on the long-span plate-truss cable-stayed bridge.Comparison of the influence of different train speeds and stiffness of the elastic vibration-damping pad on the dynamic responses of the bridge deck and the bed slab is also made.The reasonable stiffness value of elastic vibration-damping pad is proposed.展开更多
The span of coordinate time series affects the determination of an optimal noise model. We analyzed position data recorded for 10 continuous Global Positioning System （GPS） sites from 1998.0 to mid-2009 on the Austr...The span of coordinate time series affects the determination of an optimal noise model. We analyzed position data recorded for 10 continuous Global Positioning System （GPS） sites from 1998.0 to mid-2009 on the Australian Plate to estimate the best noise model and thereafter obtain the true uncertainties of the velocity, employing the maximum likelihood estimation （MLE） method. MLE was employed to analyze the data in four ways. In the first two analyses, the noise was assumed to be a combination of flicker noise and white noise for the raw time series and spatially filtered time series. In the final two analyses, the spectral indices and amplitudes were simultaneously estimated for a power law noise plus white noise model for the raw time series and spatially filtered time series. We conclude that the noise model of GPS time series in Australia can be best described as the combination of flicker noise and white noise. Velocity uncertainties fall below -0.2 mm/yr when the time span exceeds -9.5 years. A comparison of noise amplitudes and maximum likelihood estimation values between the raw and spatially filtered time series suggests that traditional spatial filtering to remove common-mode errors might not be applicable to the raw time series of this region.展开更多
The structural and tectonic evolution of the Bengal Basin is characterized by a complex interplay of factors, including sedimentation, the rise of the Himalayan Mountains, and the movements of Jurassic syn-rift faults...The structural and tectonic evolution of the Bengal Basin is characterized by a complex interplay of factors, including sedimentation, the rise of the Himalayan Mountains, and the movements of Jurassic syn-rift faults. This study aims to comprehend the progression of growth faults inside the basin by examining fault geometry, basin development, and structural relief patterns. We used high-quality 2D seismic lines from the PK-MY-8403, classical seismic interpretation techniques and modeling were carried out to reveal the plate tectonic conditions, stratigraphy, and sedimentation history of the basin. The break-up unconformity, Paleocene and Eocene submerged conditions, and crucial geological formations including the Sylhet Limestone, Barail Group, and Surma Group were among the notable features recognized in seismic section. With an emphasis on growth strata and pre-growth strata, significant variations in layer thickness and relief were remarked in different stratigraphic levels. Basin development events like the evolution of the Miocene remnant ocean basin, sedimentation in Oligocene, Eocene Himalayan collision, and the Pliocene reverse fault development are analyzed. In the early the Pliocene compressional forces outpaced sedimentation rates and syn-depositional normal faults of Oligocene time began to move in opposite direction. Syn-depositional growth faults may have formed in the Bengal Basin as a result of this reversal. This research provides a detailed comprehensive knowledge of growth fault development in the Bengal Basin following the seismic interpretation, modelling, and thickness/relief analysis. The outcomes point to a substantial hydrocarbon potential, especially in regions like the Eocene Hinge Zone, where the prospectivity of the area is enhanced by carbonate reefs and Jalangi shale. However, the existence of petroleum four-way closure in the investigated region requires further investigation.展开更多
基金supported by SNSF grant IZKOZ-2_154380partly supported by SNF 200021_149252
文摘To better understand Earth's present tectonic style-plate tectonics—and how it may have evolved from single plate(stagnant lid) tectonics, it is instructive to consider how common it is among similar bodies in the Solar System. Plate tectonics is a style of convection for an active planetoid where lid fragment(plate) motions reflect sinking of dense lithosphere in subduction zones, causing upwelling of asthenosphere at divergent plate boundaries and accompanied by focused upwellings, or mantle plumes;any other tectonic style is usefully called "stagnant lid" or "fragmented lid". In 2015 humanity completed a 50+ year effort to survey the 30 largest planets, asteroids, satellites, and inner Kuiper Belt objects,which we informally call "planetoids" and use especially images of these bodies to infer their tectonic activity. The four largest planetoids are enveloped in gas and ice(Jupiter, Saturn, Uranus, and Neptune)and are not considered. The other 26 planetoids range in mass over 5 orders of magnitude and in diameter over 2 orders of magnitude, from massive Earth down to tiny Proteus; these bodies also range widely in density, from 1000 to 5500 kg/m^3. A gap separates 8 silicate planetoids with ρ = 3000 kg/m^3 or greater from 20 icy planetoids(including the gaseous and icy giant planets) with ρ = 2200 kg/m^3 or less. We define the "Tectonic Activity Index"(TAI), scoring each body from 0 to 3 based on evidence for recent volcanism, deformation, and resurfacing(inferred from impact crater density). Nine planetoids with TAI = 2 or greater are interpreted to be tectonically and convectively active whereas 17 with TAI <2 are inferred to be tectonically dead. We further infer that active planetoids have lithospheres or icy shells overlying asthenosphere or water/weak ice. TAI of silicate(rocky) planetoids positively correlates with their inferred Rayleigh number. We conclude that some type of stagnant lid tectonics is the dominant mode of heat loss and that plate tectonics is unusual. To make progress understanding E
基金supported by the National Natural Science Foundation of China(Grant No.NNSF-U1334201)the National Basic Research Program of China("973"Project)(Grant No.2013CB036206)the Sichuan Province Youth Science and Technology Innovation Team(Grant No.2015TD0004)
文摘An analytical model is presented to study vertical dynamic response of the ballastless track on long-span plate-truss cable-stayed bridges based on an explicit dynamic analysis method.In the model,the train,ballastless track and bridge are treated as a coupled vibration system with interaction.By simulating the dynamic process of the system,this paper discusses the distribution law of dynamic responses of the bridge deck and the bed slab.It shows the necessity of a base plate for the ballastless track on the long-span plate-truss cable-stayed bridge.Comparison of the influence of different train speeds and stiffness of the elastic vibration-damping pad on the dynamic responses of the bridge deck and the bed slab is also made.The reasonable stiffness value of elastic vibration-damping pad is proposed.
基金supported by the National Natural Science Foundation of China(Grant Nos.41304007,41074022)the Chinese Universities Scientific Fund(Grant No.121103)+1 种基金the Surveying and Mapping Basic Research Program of the National Administration of Surveying,Mapping and Geoinformation(Grant No.11-02-02)the China Scholarship Council and College of Science of the University of Nevada,Reno
文摘The span of coordinate time series affects the determination of an optimal noise model. We analyzed position data recorded for 10 continuous Global Positioning System （GPS） sites from 1998.0 to mid-2009 on the Australian Plate to estimate the best noise model and thereafter obtain the true uncertainties of the velocity, employing the maximum likelihood estimation （MLE） method. MLE was employed to analyze the data in four ways. In the first two analyses, the noise was assumed to be a combination of flicker noise and white noise for the raw time series and spatially filtered time series. In the final two analyses, the spectral indices and amplitudes were simultaneously estimated for a power law noise plus white noise model for the raw time series and spatially filtered time series. We conclude that the noise model of GPS time series in Australia can be best described as the combination of flicker noise and white noise. Velocity uncertainties fall below -0.2 mm/yr when the time span exceeds -9.5 years. A comparison of noise amplitudes and maximum likelihood estimation values between the raw and spatially filtered time series suggests that traditional spatial filtering to remove common-mode errors might not be applicable to the raw time series of this region.
文摘The structural and tectonic evolution of the Bengal Basin is characterized by a complex interplay of factors, including sedimentation, the rise of the Himalayan Mountains, and the movements of Jurassic syn-rift faults. This study aims to comprehend the progression of growth faults inside the basin by examining fault geometry, basin development, and structural relief patterns. We used high-quality 2D seismic lines from the PK-MY-8403, classical seismic interpretation techniques and modeling were carried out to reveal the plate tectonic conditions, stratigraphy, and sedimentation history of the basin. The break-up unconformity, Paleocene and Eocene submerged conditions, and crucial geological formations including the Sylhet Limestone, Barail Group, and Surma Group were among the notable features recognized in seismic section. With an emphasis on growth strata and pre-growth strata, significant variations in layer thickness and relief were remarked in different stratigraphic levels. Basin development events like the evolution of the Miocene remnant ocean basin, sedimentation in Oligocene, Eocene Himalayan collision, and the Pliocene reverse fault development are analyzed. In the early the Pliocene compressional forces outpaced sedimentation rates and syn-depositional normal faults of Oligocene time began to move in opposite direction. Syn-depositional growth faults may have formed in the Bengal Basin as a result of this reversal. This research provides a detailed comprehensive knowledge of growth fault development in the Bengal Basin following the seismic interpretation, modelling, and thickness/relief analysis. The outcomes point to a substantial hydrocarbon potential, especially in regions like the Eocene Hinge Zone, where the prospectivity of the area is enhanced by carbonate reefs and Jalangi shale. However, the existence of petroleum four-way closure in the investigated region requires further investigation.
