摘要:This study explores the potential of using ASTER data to extract lithology information on the ophiolitic mixtite belt in the Tonghuashan region of southern Tianshan.First,we used the band ratio to quickly obtain information on rock assemblages. Second,we chose a number of lithological identification indices that have been established in previous research,including the Quartz Index( QI),Carbonate Index( CI),and Mafic Index( MI). We used these indices to distinguish among the silicates,carbonate rocks,and mafic-ultramafic rocks in the study area,and we also compared their performance in identifying the same kind of lithology. Third,we applied the log residual algorithm method on all the shortwave infrared( SWIR) bands of the ASTER data to examine its effectiveness in detecting ophiolite ingredients. Lastly,we employed the laboratory spectral data and spectral angle mapper method to identify the spatial distribution of the ophiolite complex. Quantitative evaluation results were achieved using the confusion matrix,and the related evaluation factors were obtained after separately applying the method on the ASTER SWIR and visible and near-infrared( VNIR)-SWIR data.In this study,we found that the band ratio method is suitable for suppressing the influence of the terrain and that it helps identify and understand geological information. On the one hand,the lithology index QI( 2008) image displayed less noise and more correctness than the lithology index QI( 2005) image in displaying the spatial distribution of silicate rocks,and the lithology index CI( 2005) image was more accurate than the CI( 2003) image in the distribution of marble. On the other hand,the lithology indices MI and QI( 2008) images collated with each other well and showed most of the ultramafic rocks in the area. The log residual algorithm successfully discriminated the ophiolite complex body from the surrounding rocks at the regional scale. The method of using the standard spectral data and spectral angle mapper to detect the spatial distribution of the ophiolite complex was relatively effective,as demonstrated by comparing the results of the method with the existing geological map and field observations. The distribution of mafic-ultramafic rocks was consistent with the geological map,but the peridotite in the southeast was not extracted because it was serpentinized,and serpentine is heavily superimposed on carbonation. Some peridotite outcrops,which were not manifested in the geological map,were also found. The distributions of dunite and peridotite were similar because dunite and peridotite are mainly composed of olivine. Gabbro and diabase outcrops were small and often symbiotic in the field; thus the accuracies of their recognition were low. The scope of basalt was larger than that in field observations because mafic lava is usually symbiotic with peridotite and gabbro,and mafic lava was altered into chlorite and epidote because of the hydrothermal alteration of the greenschist facies. However,the results for marble recognition were more accurate than those for mafic-ultramafic rocks. The quantitative evaluation of the confusion matrix demonstrated that classification using the combined ASTER VNIR and SWIR bands achieves a higher overall accuracy and Kappa coefficient than those using the ASTER SWIR bands alone.The band ratio and log residual algorithm methods can obtain general lithology information on ophiolite. Applying laboratory spectral data and spectral angle mapper on ASTER VNIR-SWIR data helps achieve increasingly accurate and detailed information on the spatial distribution of ophiolite ingredients. However,the potential of using other methods in combination with the methods mentioned above must be continuously explored to improve the accuracy of lithology identification.
HONG Shunying,LIU Zhirong,SHEN Xuhui,CHEN Lize,JING Feng,DAI Yaqiong
2015, 19(2): 288-294.
摘要:We extracts multiple Line-Of-Sight( multi-LOS) coseismic deformation fields through the interferometry of three different sets of ENVISAT ASAR data in the LOS direction,and constructs a double-fault rupture model of the Gaize earthquake by integrating deformation field characteristics with focal mechanism solutions. We also inverts the coseismic slip distribution of the Gaize earthquake though the steepest descent method and the layered crustal model of CRUST2. 0 under the constraint of the quadtree resampling of multi-LOS coseismic deformation fields. Results show that the deformation residuals of inversion are effectively controlled within 0 ± 10 cm. The major slip distributions of the mainshock fault are located at a depth of 2 km to 16 km along the fault plane,with a maximum slip value of approximately 1. 34 m at a depth of 6. 4 km. The slip distributions of the aftershock fault are mostly located at a depth of 2 km to 6 km along the fault plane,with a maximum slip value of approximately 0. 90 m at a depth of 3. 52 km. Both the mainshock and aftershock faults are principally ruptured with the normal mode,and the mainshock fault is also ruptured with a slight left lateral striking,which is not obvious in the aftershock fault. When the shear modulus is set to 3. 2 ×1010Pa,the inversion seismic moments of the mainshock and aftershock are approximately 6. 34 × 1018N·m and 1. 20 × 1018N·m,which lead to moment magnitudes of Mw6. 47 and Mw5. 98,respectively.
摘要:This paper presents two temperature-emissivity separation algorithms of hyper spectral thermal airborne infrared data:the Automatic Retrieval of Temperature and Emissivity using Spectral Smoothness( ARTEMISS) algorithm and the ASTER temperature-emissivity separation( ASTER TES) algorithm. These two algorithms are applied to separate the temperature and emissivity derived from data on the Liuyuan regionusingthethermal airborne spectrographic imager. Results of the two algorithms,as applied on the data from field measurements,were analyzed and compared in terms of their image quality and accuracy. The results showed that both algorithms meet the accuracy requirements. However,some differences also exist: the ASTER TES algorithm has good image quality and high precision,where as the ARTEMISS algorithm has simple steps and an emissivity that can better reflect the differences in litho logy than the former algorithm. In practical applications,algorithms should be chosen depending on the requirements of the application.
摘要:Deformation monitoring is essential to the safe operation of seawalls. This paper reports the Interferometric Synthetic Aperture Radar( InSAR) measurement results derived from 31 Envisat ASAR images acquired over Hang zhou from 2006 to 2010,with special focus on the seawall in the Qiantang Estuary. Multi-temporal InSAR( MTInSAR) was used to extract deformation information from both Persistent Scatterers( PSs) and Distributed Scatterers( DSs),which provide dense measurement of the deformation of the seawall. Compared with the leveling measurement at 28 points,the mean error derived by InSAR is 0. 436 mm,with the largest error of 5. 016 mm,which confirms the millimeter-level precision and accuracy of the InSAR technique. A time series analysis was conducted based on these two datasets,and results showed that the subsidence of seawalls was spatially continuous and had a local negative unimodal pattern with distance. A linear tendency with minor local fluctuation was also observed in the time domain during a period of nearly seven years.
摘要:<正>近80年来中国大陆地区人口密度分界线变化 Variation of population density boundary in Mainland China in recent 80 years 封面图片是采用1935年、1964年、1982年、1990年、2000年及2010年共6年的人口统计数据,制作的近80年来中国大陆地区人口密度分界线变化图。分界线基于胡焕庸先生提出的"爱辉-腾冲"线中给定的人口比例阈值(西北部:4%;东南部96%),及洛伦兹(Lorenz)曲线原理厘定而成。自1935年以来,该分界线整体向西北方向偏移,在甘肃、宁夏回族自治区偏移较大,吉林、内蒙古自治区、陕西、云南、四川东南部次之,四川东北