In this study, we report U–Pb and Lu–Hf isotopic data for zircons from the Mesozoic sandstones of the Upper Yangtze area, which provide critical constraints on the provenance of these sediments and further shed ligh...In this study, we report U–Pb and Lu–Hf isotopic data for zircons from the Mesozoic sandstones of the Upper Yangtze area, which provide critical constraints on the provenance of these sediments and further shed light on the crustal evolution of the Upper Yangtze block. The results of isotopic chronology indicate the following：（1） The provenances of the study area are very complex, and the tectonic evolution process is relatively closed.（2） The provenances are mainly Archean–Proterozoic crystalline basement or recycled material; Paleoproterozoic crustal accretion in the western margin of the Yangtze block and Neoproterozoic magmatic activities related to subduction of the western margin of the Yangtze block; early Cambrian oceanic magmatic activity, which resulted from the intraplate extension of the northern margin of the Yangtze block; late Ordovician–early Silurian magmatic activity in the northern Yangtze block and Hercynian–Indochina uplift and erosion during the Hercynian movement.（3） The Yangtze crustal growth is episodic, and an increasing amount of ancient recycled material became part of the magmatic activity, as the zircon U–Pb ages are relatively young.展开更多
The South China block(SC),composed of Cathaysia(CA),Jiangnan Orogenic belt(JNB),and Yangtze block(YB),is one of the most important poly-metallic metallogenic provinces in the world(Zhang et al.,2013),containing of fou...The South China block(SC),composed of Cathaysia(CA),Jiangnan Orogenic belt(JNB),and Yangtze block(YB),is one of the most important poly-metallic metallogenic provinces in the world(Zhang et al.,2013),containing of four famous major Mesozoic metallogenic belts,involving the Middle-Lower Yangtze Fe-Cu-Au metallogenic belt(MYMB).展开更多
The widespread availability of digital multimedia data has led to a new challenge in digital forensics.Traditional source camera identification algorithms usually rely on various traces in the capturing process.Howeve...The widespread availability of digital multimedia data has led to a new challenge in digital forensics.Traditional source camera identification algorithms usually rely on various traces in the capturing process.However,these traces have become increasingly difficult to extract due to wide availability of various image processing algorithms.Convolutional Neural Networks(CNN)-based algorithms have demonstrated good discriminative capabilities for different brands and even different models of camera devices.However,their performances is not ideal in case of distinguishing between individual devices of the same model,because cameras of the same model typically use the same optical lens,image sensor,and image processing algorithms,that result in minimal overall differences.In this paper,we propose a camera forensics algorithm based on multi-scale feature fusion to address these issues.The proposed algorithm extracts different local features from feature maps of different scales and then fuses them to obtain a comprehensive feature representation.This representation is then fed into a subsequent camera fingerprint classification network.Building upon the Swin-T network,we utilize Transformer Blocks and Graph Convolutional Network(GCN)modules to fuse multi-scale features from different stages of the backbone network.Furthermore,we conduct experiments on established datasets to demonstrate the feasibility and effectiveness of the proposed approach.展开更多
Whole-rock major and trace element and Sr-Nd isotopic data,together with zircon LA ICP-MS in-situ U-Pb and Hf isotopic data of the syenites and granites in the Tengchong Block are reported in order to understand their...Whole-rock major and trace element and Sr-Nd isotopic data,together with zircon LA ICP-MS in-situ U-Pb and Hf isotopic data of the syenites and granites in the Tengchong Block are reported in order to understand their petrogenesis and tectonic implications.Zircon U-Pb data gives the emplacement ages of ca.115.3±0.9 Ma for syenites and 115.7±0.8 Ma for granites,respectively.The syenites are characterized by low SiO2 content(62.01-63.03 wt%)and notably high Na20 content(7.04-7.24 wt%)and Na20/K20 ratios(2.02-2.10),low MgO,Fe2OaT and TiO2,enrichment of LILEs(large-ion lithophile element)such as Rb,Th,U,K,and Pb)and obvious depletion HFSE(high field strength element;e.g.Nb,Ta,P,and Ti)with clearly negative Eu anomalies(dEu=0.53-0.56).They also display significant negative whole-rock eNd(t)values of-6.8 and zircon eHf(t)values(-9.11 to-0.27,but one is+5.30)and high initial S7Sr/86Sr=0.713013.Based on the data obtained in this study,we suggest that the ca.l15.3Ma syenites were possibly derived from a sodium-rich continental crustal source,and the fractionation of some ferro-magnesian mineral and plagioclase might occur during the evolution of magma.The granites have high SiO2 content(71.35-74.47 wt%),metaluminous to peraluminous,low Rb/Ba,Rb/Sr,and AI2Oa/(MgO+FeOT+TiO2)ratios and moderate(AI2Oa+MgO+FeOT+TiO2)content.They show low initial a7Sr/86Sr(0.703408 to 0.704241)and eNd(t)values(-3.8 to-3.5),plotted into the evolutionary trend between basalts and lower crust.Hence,we suggest that the granites were derived from the melting of mixing sources in the ancient continental crust involving some metabasaltic materials and predominated metasedimentary greywackes.Together with data in the literatures,we infer that the Early Cretaceous magmatism in the Tengchong block was dominated by magmas generated by the partial melting of ancient crustal material,which represent the products that associated to the closure of Bangong-Nujiang Meso-Tethys.展开更多
Many studies focus on mineralization of huge magnetite ore deposits and petrogenesis of their large-volume host rocks.However,magma generation of those small-scale intrusions with enrichment of magnetite is poorly rep...Many studies focus on mineralization of huge magnetite ore deposits and petrogenesis of their large-volume host rocks.However,magma generation of those small-scale intrusions with enrichment of magnetite is poorly reported and paid attention to.We here carry out an integrated study of magnetite chemistry,U-Pb zircon dating,geochemistry,and Sr-Nd-Hf isotopes for the magnetite-rich intermediate-mafic rocks from the Helishan pluton in the southwestern Alxa Block,Northwest China.This,together with several previously reported magnetite/iron-rich intrusions nearby,is capable of providing some constraints on magma generation of magnetite/iron-rich intrusive rocks.The Helishan pluton,dated at ca.290 Ma,consists of hornblende gabbro,diorite,and quartz monzodiorite with~3%-5%magnetite in all the lithologies.Study on magnetite chemistry manifests a magmatic origin for them.All the lithologies display high TFeO/MgO ratio (1.71-1.89),weakly fractionated REE patterns((La/Yb)_(N)=1.82-10.17),enrichment of Rb,Sr,and Pb,and depletion of high field strength elements.They have (^(87)Sr/^(86)Sr)_(i) values of 0.705 2 to 0.705 8,ε_(Nd)(t) values of+0.03 to+0.64,and zircon ε_(Hf)(t) values of +6.5 to+12.0.We propose that they were derived from partial melting of iron-rich metasomatized lithospheric mantle.The systematic variations of Sr/Y ratios and Nd-Hf isotopic compositions with time for the Paleozoic igneous rocks at the southwestern Alxa Block indicate ever existence of thinning and rebirth of lithospheric mantle.This geodynamic process could be the potential mechanism to give rise to the iron-rich signature of the reborn mantle sources of the Helishan pluton.For intermediatemafic intrusions at subduction zones,they are unlikely to form considerable magnetite ore deposits since their modest magmatic flux and early fractional crystallization of magnetite at a high oxygen fugacity and H_(2)O condition.展开更多
Dimensional control is one of the most important challenges in the shipbuilding industry. In order to predict assembly dimensional variation in hull flat block construction, a variation stream model based on state spa...Dimensional control is one of the most important challenges in the shipbuilding industry. In order to predict assembly dimensional variation in hull flat block construction, a variation stream model based on state space was presented in this paper which can be further applied to accuracy control in shipbuilding. Part accumulative error, locating error, and welding deformation were taken into consideration in this model, and variation propagation mechanisms and the accumulative rule in the assembly process were analyzed. Then, a model was developed to describe the variation propagation throughout the assembly process. Finally, an example of fiat block construction from an actual shipyard was given. The result shows that this method is effective and useful.展开更多
Based on P- and S-wave amplitudes and some clear initial P-wave motion data, we calculated focal mechanism solutions of 928 M≥2.5 earthquakes （1994-2005） in four sub-blocks of Sichuan and Yunnan Provinces, namely S...Based on P- and S-wave amplitudes and some clear initial P-wave motion data, we calculated focal mechanism solutions of 928 M≥2.5 earthquakes （1994-2005） in four sub-blocks of Sichuan and Yunnan Provinces, namely Sichuan-Qinghai, Yajiang, Central Sichuan and Central Yunnan blocks. Combining these calculation results with those of the focal mechanism solutions of moderately strong earthquakes, we analyzed the stress field characteristics and dislocation types of seismogenic faults that are distributed in the four sub-blocks. The orientation of principal compressive stress for each block is： EW in Sichuan-Qinghai, ESE or SE in Yajiang, Central Sichuan and Central Yunnan blocks. Based on a great deal of focal mechanism data, we designed a program and calculated the directions of the principal stress tensors, σ1, σ2 and σ3, for the four blocks. Meanwhile, we estimated the difference （also referred to as consistency parameter θ^- ） between the force axis direction of focal mechanism solution and the direction of the mean stress tensor of each block. Then we further analyzed the variation of θ^- versus time and the dislocation types of seismogenic faults. Through determination of focal mechanism solutions for each block, we present information on the variation in θ^- value and dislocation types of seismogenic faults.展开更多
基金financially supported by the China Geological Survey(CGS,Grant No.DD20160183)the Major State Research Development Program of China(Grant No.2016YFC0600202)
文摘In this study, we report U–Pb and Lu–Hf isotopic data for zircons from the Mesozoic sandstones of the Upper Yangtze area, which provide critical constraints on the provenance of these sediments and further shed light on the crustal evolution of the Upper Yangtze block. The results of isotopic chronology indicate the following：（1） The provenances of the study area are very complex, and the tectonic evolution process is relatively closed.（2） The provenances are mainly Archean–Proterozoic crystalline basement or recycled material; Paleoproterozoic crustal accretion in the western margin of the Yangtze block and Neoproterozoic magmatic activities related to subduction of the western margin of the Yangtze block; early Cambrian oceanic magmatic activity, which resulted from the intraplate extension of the northern margin of the Yangtze block; late Ordovician–early Silurian magmatic activity in the northern Yangtze block and Hercynian–Indochina uplift and erosion during the Hercynian movement.（3） The Yangtze crustal growth is episodic, and an increasing amount of ancient recycled material became part of the magmatic activity, as the zircon U–Pb ages are relatively young.
基金jointly sponsored by the National Natural Science Foundation of China(Grant Nos.41630320,92062108)the Geology Survey Project(Grant Nos.DD20190012,DD20160082)the Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resource,Institute of Geology,Chinese Academy of Geological Sciences(Grant No.J1901-16)
文摘The South China block(SC),composed of Cathaysia(CA),Jiangnan Orogenic belt(JNB),and Yangtze block(YB),is one of the most important poly-metallic metallogenic provinces in the world(Zhang et al.,2013),containing of four famous major Mesozoic metallogenic belts,involving the Middle-Lower Yangtze Fe-Cu-Au metallogenic belt(MYMB).
基金This work was funded by the National Natural Science Foundation of China(Grant No.62172132)Public Welfare Technology Research Project of Zhejiang Province(Grant No.LGF21F020014)the Opening Project of Key Laboratory of Public Security Information Application Based on Big-Data Architecture,Ministry of Public Security of Zhejiang Police College(Grant No.2021DSJSYS002).
文摘The widespread availability of digital multimedia data has led to a new challenge in digital forensics.Traditional source camera identification algorithms usually rely on various traces in the capturing process.However,these traces have become increasingly difficult to extract due to wide availability of various image processing algorithms.Convolutional Neural Networks(CNN)-based algorithms have demonstrated good discriminative capabilities for different brands and even different models of camera devices.However,their performances is not ideal in case of distinguishing between individual devices of the same model,because cameras of the same model typically use the same optical lens,image sensor,and image processing algorithms,that result in minimal overall differences.In this paper,we propose a camera forensics algorithm based on multi-scale feature fusion to address these issues.The proposed algorithm extracts different local features from feature maps of different scales and then fuses them to obtain a comprehensive feature representation.This representation is then fed into a subsequent camera fingerprint classification network.Building upon the Swin-T network,we utilize Transformer Blocks and Graph Convolutional Network(GCN)modules to fuse multi-scale features from different stages of the backbone network.Furthermore,we conduct experiments on established datasets to demonstrate the feasibility and effectiveness of the proposed approach.
基金supported by the National Natural Science Foundation of China(Grant Nos.41421002,41190072,41372067 and 41102037)the program for Changjiang Scholars and Innovative Research Team in University(Grant IRT1281)+2 种基金the Foundation for the Author of National Excellent Doctoral Dissertation of PR China(201324)the MOST Special Fund from the State Key Laboratory of Continental Dynamics,Northwest UniversityProvince Key Laboratory Construction Item(08JZ62)
文摘Whole-rock major and trace element and Sr-Nd isotopic data,together with zircon LA ICP-MS in-situ U-Pb and Hf isotopic data of the syenites and granites in the Tengchong Block are reported in order to understand their petrogenesis and tectonic implications.Zircon U-Pb data gives the emplacement ages of ca.115.3±0.9 Ma for syenites and 115.7±0.8 Ma for granites,respectively.The syenites are characterized by low SiO2 content(62.01-63.03 wt%)and notably high Na20 content(7.04-7.24 wt%)and Na20/K20 ratios(2.02-2.10),low MgO,Fe2OaT and TiO2,enrichment of LILEs(large-ion lithophile element)such as Rb,Th,U,K,and Pb)and obvious depletion HFSE(high field strength element;e.g.Nb,Ta,P,and Ti)with clearly negative Eu anomalies(dEu=0.53-0.56).They also display significant negative whole-rock eNd(t)values of-6.8 and zircon eHf(t)values(-9.11 to-0.27,but one is+5.30)and high initial S7Sr/86Sr=0.713013.Based on the data obtained in this study,we suggest that the ca.l15.3Ma syenites were possibly derived from a sodium-rich continental crustal source,and the fractionation of some ferro-magnesian mineral and plagioclase might occur during the evolution of magma.The granites have high SiO2 content(71.35-74.47 wt%),metaluminous to peraluminous,low Rb/Ba,Rb/Sr,and AI2Oa/(MgO+FeOT+TiO2)ratios and moderate(AI2Oa+MgO+FeOT+TiO2)content.They show low initial a7Sr/86Sr(0.703408 to 0.704241)and eNd(t)values(-3.8 to-3.5),plotted into the evolutionary trend between basalts and lower crust.Hence,we suggest that the granites were derived from the melting of mixing sources in the ancient continental crust involving some metabasaltic materials and predominated metasedimentary greywackes.Together with data in the literatures,we infer that the Early Cretaceous magmatism in the Tengchong block was dominated by magmas generated by the partial melting of ancient crustal material,which represent the products that associated to the closure of Bangong-Nujiang Meso-Tethys.
基金supported by the National Natural Science Foundation of China(No.41573021)the Most Special Fund from the State Key Laboratory of Geological Processes and Mineral Resources(No.MSFGPMR201601-2)。
文摘Many studies focus on mineralization of huge magnetite ore deposits and petrogenesis of their large-volume host rocks.However,magma generation of those small-scale intrusions with enrichment of magnetite is poorly reported and paid attention to.We here carry out an integrated study of magnetite chemistry,U-Pb zircon dating,geochemistry,and Sr-Nd-Hf isotopes for the magnetite-rich intermediate-mafic rocks from the Helishan pluton in the southwestern Alxa Block,Northwest China.This,together with several previously reported magnetite/iron-rich intrusions nearby,is capable of providing some constraints on magma generation of magnetite/iron-rich intrusive rocks.The Helishan pluton,dated at ca.290 Ma,consists of hornblende gabbro,diorite,and quartz monzodiorite with~3%-5%magnetite in all the lithologies.Study on magnetite chemistry manifests a magmatic origin for them.All the lithologies display high TFeO/MgO ratio (1.71-1.89),weakly fractionated REE patterns((La/Yb)_(N)=1.82-10.17),enrichment of Rb,Sr,and Pb,and depletion of high field strength elements.They have (^(87)Sr/^(86)Sr)_(i) values of 0.705 2 to 0.705 8,ε_(Nd)(t) values of+0.03 to+0.64,and zircon ε_(Hf)(t) values of +6.5 to+12.0.We propose that they were derived from partial melting of iron-rich metasomatized lithospheric mantle.The systematic variations of Sr/Y ratios and Nd-Hf isotopic compositions with time for the Paleozoic igneous rocks at the southwestern Alxa Block indicate ever existence of thinning and rebirth of lithospheric mantle.This geodynamic process could be the potential mechanism to give rise to the iron-rich signature of the reborn mantle sources of the Helishan pluton.For intermediatemafic intrusions at subduction zones,they are unlikely to form considerable magnetite ore deposits since their modest magmatic flux and early fractional crystallization of magnetite at a high oxygen fugacity and H_(2)O condition.
基金Supported by the National Science Foundation of China （Granted No.70872076） and Science Innovation Action Planning of Shanghai 2011 （No.11dz1121803）.
文摘Dimensional control is one of the most important challenges in the shipbuilding industry. In order to predict assembly dimensional variation in hull flat block construction, a variation stream model based on state space was presented in this paper which can be further applied to accuracy control in shipbuilding. Part accumulative error, locating error, and welding deformation were taken into consideration in this model, and variation propagation mechanisms and the accumulative rule in the assembly process were analyzed. Then, a model was developed to describe the variation propagation throughout the assembly process. Finally, an example of fiat block construction from an actual shipyard was given. The result shows that this method is effective and useful.
基金National Key Basic Research Development and Programming Project (2004CB418404) and Joint Seismological Science Foundation (105004).
文摘Based on P- and S-wave amplitudes and some clear initial P-wave motion data, we calculated focal mechanism solutions of 928 M≥2.5 earthquakes （1994-2005） in four sub-blocks of Sichuan and Yunnan Provinces, namely Sichuan-Qinghai, Yajiang, Central Sichuan and Central Yunnan blocks. Combining these calculation results with those of the focal mechanism solutions of moderately strong earthquakes, we analyzed the stress field characteristics and dislocation types of seismogenic faults that are distributed in the four sub-blocks. The orientation of principal compressive stress for each block is： EW in Sichuan-Qinghai, ESE or SE in Yajiang, Central Sichuan and Central Yunnan blocks. Based on a great deal of focal mechanism data, we designed a program and calculated the directions of the principal stress tensors, σ1, σ2 and σ3, for the four blocks. Meanwhile, we estimated the difference （also referred to as consistency parameter θ^- ） between the force axis direction of focal mechanism solution and the direction of the mean stress tensor of each block. Then we further analyzed the variation of θ^- versus time and the dislocation types of seismogenic faults. Through determination of focal mechanism solutions for each block, we present information on the variation in θ^- value and dislocation types of seismogenic faults.
