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1.
Multispectral, multiresolution remotely sensed data were processed to emphasize geological interpretation of Jabal Daf-Wadi Fatima area. The investigated area is situated in the central western part of Saudi Arabia and geologically consists of igneous and metamorphosed rocks overlain by sedimentary sequence belonging to the Arabian-Nubian Shield. Three sets of digital satellite data, Landsat-7 ETM+, ASTER, and SPOT-5, were used in this study. The application of image processing techniques enables to identify and delineate the lithologic units and the structural features of the study area. The results of this study indicate that the confusion matrix of the three maximum likelihood supervised classifications of the three datasets shows that the Landsat ETM+ bands scored the best degree of average and overall accuracy (77 and 78%, respectively). This classification distinguishes most of the rock units for mapping in the investigated area. The supervised classification of ASTER and SPOT bands has lower degrees of accuracy than the classified Landsat data. The supervised classification of SPOT bands has a degree of average and overall accuracy of 66 and 67%, respectively, but it is the best for distinguishing the spectral signatures of the different members of Fatima Formation (lower, middle, and upper members). The statistical analyses of the confusion matrices of classifications and the interpretation of the produced classified thematic maps revealed that the classification accuracy does not necessary depend on the spatial resolution of satellite data. The data of the highest spatial resolution such as SPOT data are also very useful in emphasizing and classifying the rock units of a small outcrop area. The detailed geological map of Jabal Daf-Wadi Fatima area is interpreted in this work from supervised classified images of different resolutions as well as the structure map of this area. This study shows that it is preferable to use the supervised classifications of multiresolution data for rock unit discrimination in detailed field mapping.  相似文献   

2.
Podiform chromite ore deposits in ultramafic parts of ophiolite rock complexes can be detected using remote sensing data. This study focuses on the discrimination of chromite bearing mineralized zones using Landsat TM and Advance Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite data in Abdasht ophiolite complex, south of Iran. Several image processing methods, including Log residual, Decorellation Stretch, Band ratio and Mixture-Tuned Matched-Filtering (MTMF) have been evaluated for lithological mapping using Landsat ETM and ASTER data. The outcome showed that TIR band ratios of ASTER can discriminate quartzite, carbonate and mafic–ultramafic rocks in the ophiolite complex. Log residual, Decorollation Stretch and MTMF methods were more capable than previous published ASTER methods specifically for lithological mapping at a regional scale. New geological map of Abdasht region was produced based on the interpretation of ASTER image processing results and field verification. Consequently, the proposed methods demonstrated the ability of ASTER and Landsat ETM data to provide information for detecting chromite host rock (serpentinized dunites) that is valuable for chromite prospecting in study area. Additionally, the techniques used in this study are subtle for exploration geologist and mine engineering to identify high-potential chromite-bearing zones in the ophiolite complex, minimizing costly and time-consuming field works.  相似文献   

3.
以ETM、SPOT5和Quickbird为主要信息源,在哈拉阿拉特山地区开展1:5万区域地质填图,对该地区的地层单元、中—小规模地质体(如岩脉、小岩体和火山口)和地质构造特征进行了详细地遥感解译分析,并开展了大量的遥感野外地质调查验证.结果表明,采用彩色空间HSV变换融合法将SPOT5高精度遥感图像数据与ETM图像数据...  相似文献   

4.
This study evaluates the use of image processing techniques and methodologies of digital integration of multi-disciplinary geoscientific data to reduce the ambiguity in geological interpretations in different geological environments in Libya. To realize this objective, three areas were selected for this study; Eljufra, an arid environment; the mountainous environment Tarhunah; and the Jifara Plain, a coastal plain environment. Two types of remote sensing data were used in this study: Landsat Enhanced Thematic Mapper Plus (ETM+) and European Remote Sensing Satellite. The digital elevation model extracted from Shuttle Radar Topography Mission and digital topographic maps scale 1:50,000 were used for remote sensing interpretation. GIS and remote sensing-based methods were used to process and integrate all raster and vector layers data. This study offered dramatic benefits for geological interpretations and provided new insights into the efficiency of image processing methods in different geological environments.  相似文献   

5.
对1999年的喀拉米兰河-克里雅河流内流区的Landsat ETM+影像运用非监督分类、监督分类,雪盖指数域值法和比值域值法提取其中176条冰川的边界信息,并与目视解译结果进行定量比较,结果表明:比值域值法精度最高,达98.32%;将比值域值法提取1999年的冰川边界与1970年航测地形图勾绘的冰川边界进行叠加分析,得到整个流域29 a来的冰川变化信息.统计表明,流域冰川条数减少了0.6%,总面积萎缩了2.86%,总冰储量减少了3.10%,大多数冰川处于稳定状态.  相似文献   

6.
Structural maps are traditionally produced by mapping features such as faults, folds, fabrics, fractures and joints in the field. However, large map areas and the spatially limited ground perspective of the field geologist can potentially increase the likelihood that not all structural features will be identified within a given area. The ability to recognise and map both local and regional structural features using high-resolution remote sensing data provides an opportunity to complement field-based mapping to help generate more comprehensive structural maps. Nonetheless, vegetation cover can adversely affect the extraction of structural information from remotely sensed data as it can mask the appearance of subtle spectral and geomorphological features that correspond to geological structures. This study investigates the utility of airborne Light Detection And Ranging (LiDAR) data and airborne multispectral imagery for detailed structural mapping in vegetated ophiolitic rocks and sedimentary cover of a section of the northern Troodos ophiolite, Cyprus. Visual enhancement techniques were applied to a 4-m airborne LiDAR digital terrain model and 4-m airborne multispectral imagery to assist the generation of structural lineament maps. Despite widespread vegetation cover, dykes and faults were recognisable as lineaments in both data sets, and the predominant strike trends of lineaments in all resulting maps were found to be in agreement with field-based structural data. Interestingly, prior to fieldwork, most lineaments were assumed to be faults, but were ground-verified as dykes instead, emphasising the importance of ground-truthing. Dyke and fault trends documented in this study define a pervasive structural fabric in the upper Troodos ophiolite that reflects the original sea-floor spreading history in the Larnaca graben. This structural fabric has not previously been observed in such detail and is likely to be continuous in adjacent regions under sedimentary cover. This information may be useful to future exploration efforts in the region focused on identification of structurally controlled mineral and groundwater resources. Overall, our case study highlights the efficacy of airborne LiDAR data and airborne multispectral imagery for extracting detailed and accurate structural information in hard-rock terrain to help complement field-based mapping.  相似文献   

7.
The study area comprises the southeastern part of the Western Desert of Egypt. The aims of the present study are to delineate the major surface and subsurface structures and to evaluate tectonic framework of the study area. Surface studies of the present work are based mainly on data from two different types of remote sensing systems: 15 cloud-free Landsat Enhanced Thematic Mapper Plus (ETM+) images and Shuttle Radar Topography Mission (SRTM) DEM data. The remote sensing data were used to recognize and extract geological lineaments by calculating and interpreting DEM derivatives, including shaded relief maps, slope maps, and traverse profiles. A Bouguer anomaly map (scale 1:500,000) was used to delineate a detailed picture of the subsurface structure in the study area. The analysis of surface data, including SRTM DEM and ETM+, was combined with subsurface data, including Bouguer anomaly map, and gave new insight into the tectonic and structure patterns of the study area.  相似文献   

8.
Chromite deposits in Iran are located in the ophiolite complexes, which have mostly podiform types and irregular in their settings. Exploration for podiform chromite deposits associated with ophiolite complexes has been a challenge for the prospectors due to tectonic disturbance and their distribution patterns. Most of Iranian ophiolitic zones are located in mountainous and inaccessible regions. Remote sensing approach could be applicable tool for choromite prospecting in Iranian ophiolitic zones with intensely rugged topography, where systematic sampling and conventional geological mapping are limited. In this study, Landsat Thematic Mapper (TM) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite data were used for chromite prospecting and lithological mapping in the Neyriz ophiolitic zone in the south of Iran. Image transformation techniques, namely decorrelation stretch, band ratio and principal component analysis (PCA) were applied to Landsat TM and ASTER data sets for lithological mapping at regional scale. The RGB decorrelated image of Landsat TM spectral bands 7, 5, and 4, and the principal components PC1, PC2 and PC3 image of ASTER SWIR spectral bands efficiently showed the occurrence of major lithological units in the study area at regional scale. The band ratios of 5/3, 5/1, 7/5 applied on ASTER VNIR‐SWIR bands were very useful for discriminating most of rock units in the study area and delineation of the transition zone and mantle harzburgite in the Neyriz ophiolitic complex. Spectral Angle Mapper (SAM) technique was implemented to ASTER VNIR‐SWIR spectral bands for detecting minerals of rock units and especially delineation of the transition zone and mantle harzburgite as potential zones with high chromite mineralization in the Neyriz ophiolitic complex. The integration of information extracted from the image processing algorithms used in this study mapped most of lithological units of the Neyriz ophiolitic complex and identified potential areas of high chromite mineralization (transition zone and mantle harzburgite) for chromite prospecting targets in the future. Furthermore, image processing results were verified by comprehensive fieldwork and laboratory analysis in the study area. Accordingly, result of this investigation indicate that the integration of information extracted from the image processing algorithms using Landsat TM and ASTER data sets could be broadly applicable tool for chromite prospecting and lithological mapping in mountainous and inaccessible regions such Iranian ophiolitic zones.  相似文献   

9.
This study examines linear spectral unmixing technique for mapping the surface soil types using field spectroscopy data as the reference spectra. The investigated area is located in North Sinai, Egypt. The study employed data from the Landsat 7 ETM+ satellite sensor with improved spatial and spectral resolution. Mixed remotely sensed image pixels may lead to inaccurate classification results in most conventional image classification algorithms. Spectral unmixing may solve this problem by resolving those into separate components. Four soil type end-members were identified with minimum noise fraction and pixel purity index analyses. The identified soil types are calcareous soils, dry sabkhas, wet sabkhas, and sand dunes. Soil end-member reference spectra were collected in the field using an ASD FieldSpec Pro spectrometer. Constrained sum-to-one and non-negativity linear spectral unmixing model was applied and the soil types map was produced. The results showed that linear spectral unmixing model can be a useful tool for mapping soil types from ETM+ images.  相似文献   

10.
Comparing satellite data derived map products are affected by differences in data characteristics, image acquisition dates, processing techniques, and classification schemes used for assigning pixels to a thematic class. By comparing two forest maps generated from Landsat Enhanced Thematic Mapper Plus (ETM+) and Advanced Very High Resolution Radiometer (AVHRR) images acquired on the same day, and processed using identical classification scheme and methods these differences were minimized. The ETM+ derived map had higher classification accuracy values and more precise area estimates than the AVHRR derived map. In the ETM+ derived map, 87 of the 599 verification data were misclassified, whereas in the AVHRR derived map, 155 of the 469 verification data were misclassified. Detailed error analyses by land cover class revealed that a land use based definition of forest accounted for 74% (64 out of 87) and 57% (89 out of 155) of the classification errors in ETM+ and AVHRR derived maps, respectively.  相似文献   

11.
H.M. Rajesh   《Ore Geology Reviews》2008,33(3-4):382-396
The Rockhole area, Northern Territory, Australia, hosts a number of Proterozoic unconformity-related uranium deposits. The geology of the area features within Paleoproterozoic rocks of the Pine Creek Orogen, near the unconformity with overlying platform cover sandstone of the Paleo- to Mesoproterozoic McArthur Basin. Landsat Enhanced Thematic Mapper plus (ETM+) data was used in the Rockhole area to assist in mapping geological structures and lithology, and to identify anomalous concentrations of ferrous minerals, the product of alteration, which can be indicators of buried uranium mineralization. Several image-processing procedures were applied to the ETM+ data to identify, isolate and enhance mineralogical information as simple and complex false color composites. ETM+ 754 shown as red green and blue respectively was the best simple image. Overall, complex images based on Principal Component Analysis proved to be the most useful products. Sandstone, shale and siltstone, the target lithologies, Koolpin Formation, the target stratigraphic unit, and bleaching pattern due to the removal of iron(II) compounds, the target alteration pattern, were confidently mapped to provide information required by the mineral emplacement model, which ultimately identified areas of likely uranium mineralization. Thus the contrasting behavior of the two principle oxidation states of uranium and iron can be utilized to map/delineate bleached alteration zones associated with economic concentrations of uranium using multispectral sensors like Landsat or better hyperspectral sensors.  相似文献   

12.
The Neoproterozoic Wadi Kid metamorphic belt in southeastern Sinai in Egypt represents a structurally and metamorphically complex assemblage of metasedimentary and metavolcanic rocks folded into a series of ENE–WSW-trending antiforms and synforms. Geological mapping in this region is challenging, primarily due to difficult access, complexity of structures, and lack of resolution and areal integrity of lithological differentiation using conventional mapping techniques. Spectral ratioing of selected bands of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data of the area, in synergy with geological field observation, proved effective in resolving geological mapping problems in the region. A new ASTER band-ratio image 4/7-4/6-4/10 is applied successfully for lithological mapping in the Wadi Kid area, showing improvement over previous techniques in detailing the main rock units. These are gneiss and migmatite, amphibolite, volcanogenic sediments with banded iron formation, meta-pelites, talc schist, meta-psammites, meta-acidic volcanics, meta-pyroclastics volcaniclastics, albitites and granitic rocks. Validating the use of the new ASTER band-ratio image relied on both calculating statistical optimum index factor (OIF) and matching interpreted lithological boundaries to field data and previously published geologic maps. The adopted ASTER band-ratio image demonstrates the benefit of using ASTER remote sensing data in lithological mapping of the Wadi Kid area and therefore for lithological mapping in the Arabian–Nubian shield and other arid areas.  相似文献   

13.
针对冰川遥感监测研究工作中存在的数据源选择问题,首次将国产高分一号卫星数据应用于祁连山系青海境内冰川动态变化监测工作.通过国产高分遥感数据与同尺度的Landsat历史数据对比,从变化面积、变化率、空间变化、类型变化、结构变化等方面阐述祁连山系冰川变化规律.研究对比表明：国产高分卫星遥感数据在采集、处理、监测冰川变化中的应用效果完全可以满足1：10万尺度的遥感调查和监测,不管是光谱信息还是纹理信息都优于ETM等中低分辨率数据;国产高分卫星的多光谱数据与Landsat、Aster等历史数据可以形成对比数据集;祁连山系冰川总体变化不大,但在内部结构与时空分布存在较大差异,冰川面积和数量呈双降态势;针对冰川的特殊性,能保证在每年的最佳季节获取最优质的遥感数据,对于时间跨度大的遥感监测目标监测具有重要意义.  相似文献   

14.
In recent years, remote-sensing data have increasingly been used for the interpretation of objects and mapping in various applications of engineering geology. Digital elevation model (DEM) is very useful for detection, delineation, and interpretation of geological and structural features. The use of image elements for interpretation is a common method to extract structural features. In this paper, linear features were extracted from the Landsat ETM satellite image and then DEM was used to enhance those objects using digital-image-processing filtering techniques. The extraction procedures of the linear objects are performed in a semi-automated way. Photographic elements and geotechnical elements are used as main keys to extract the information from the satellite image data. This paper emphasizes on the application of DEM and usage of various filtering techniques with different convolution kernel size applied on the DEM. Additionally, this paper discusses about the usefulness of DEM and satellite digital data for extraction of structural features in SW of Zagros mountain, Iran.  相似文献   

15.
The logistic regression and statistical index models are applied and verified for landslide susceptibility mapping in Daguan County, Yunnan Province, China, by means of the geographic information system (GIS). A detailed landslide inventory map was prepared by literatures, aerial photographs, and supported by field works. Fifteen landslide-conditioning factors were considered: slope angle, slope aspect, curvature, plan curvature, profile curvature, altitude, STI, SPI, and TWI were derived from digital elevation model; NDVI was extracted from Landsat ETM7; rainfall was obtained from local rainfall data; distance to faults, distance to roads, and distance to rivers were created from a 1:25,000 scale topographic map; the lithology was extracted from geological map. Using these factors, the landslide susceptibility maps were prepared by LR and SI models. The accuracy of the results was verified by using existing landslide locations. The statistical index model had a predictive rate of 81.02%, which is more accurate prediction in comparison with logistic regression model (80.29%). The models can be used to land-use planning in the study area.  相似文献   

16.
By means of multi-temporal analysis of satellite images and statistical algorithms, the amount of pyroclastic material deposited on Lascar volcano walls after the gravitational collapse of the eruptive column caused by the eruption that occurred on April the 19th and the 20th in 1993 was determined and quantified. For this analysis, scenes corresponding to Landsat 4 TM in 1989 and Landsat 7 ETM+ in 2001 were used. By careful selection methods such as combination of bands, unsupervised classification, and the Karhunen–Loève transform, detailed analysis of zones of change that correspond to pyroclastic deposits were made. This analysis was complemented with in situ data in order to correct and calibrate the satellite images to identify zones of 1993s eruption pyroclastic deposits. Using Kittler’s and other thresholding algorithms, a search was performed for a proper threshold to binarize the images to determine the surface area covered by the eruptive process. Matlab™ software was used both for general programming and for digital image processing.  相似文献   

17.
The curve number (CN) is a hydrologic parameter used to describe the stormwater runoff potential for drainage areas, and it is a function of land use, soil type, and soil moisture. This study was conducted to estimate the potential runoff coefficient (PRC) using geographic information system (GIS) based on the area’s hydrologic soil group, land use, and slope and to determine the runoff volume. The soil map for the study area was developed using GPS data carried on to identify the soil texture to be used in building a soil hydrological groups map. Unsupervised and supervised classifications were done to Landsat 5/7 TM/ETM image to generate land-use and land-cover map. This map was reclassified into four main classes (forest, grass and shrub, cropland, and bare soil). Slope map for Al-Baha was generated from a 30-m digital elevation model. The GIS technique was used to combine the previous three maps into one map to generate PRC map. Annual runoff depth is derived based on the annual rainfall surplus and runoff coefficient per pixel using raster calculator tool in ArcGIS. An indication that in the absence of reliable ground measurements of rainfall product, it can satisfactorily be applied to estimate the spatial rainfall distribution based on values of R and R 2 (0.9998) obtained. Annual runoff generation from the study area ranged from 0 to 82 % of the total rainfall. Rainfall distribution in the study area shows the wise use of identifying suitable sites for rainwater harvesting, where most of the constructed dams are located in the higher rainfall areas.  相似文献   

18.
招平断裂带是胶东地区重要的控矿构适之一,文章中遥感地质研究的范围包括其北段、中段及外围区,测区面积1200km2.ETM多光谱遥感数据来源于美国7号陆地卫星.选择ETM7、4、1三个波段进行彩色合成制作测区基础遥感图像.采用Crosta法,选择ETM1、4、5、7波段作为输入波段进行主成分变换,获取泥化蚀变遥感信息.选...  相似文献   

19.
 The Cabo de Gata Níjar Natural Park in Spain presents certain unique characteristics which make it of great geological, ecological and environmental interest. As a prior step to the environmental study of the park and the impact produced by the mining activities carried out up until ten years ago, the mining and waste-tip areas were defined and a lithological discrimination carried out. For this purpose, various remote-sensing techniques were employed to create high-resolution image documents on which the geological and environmental mapping of the area would be based, with special attention being paid to the areas of former mining activity because of its implications for the local environment. The merging of remote-sensing images with different spatial/spectral resolutions has become a highly useful tool, due to their increasing availability. Such is the case of the SPOT panchromatic and Landsat Thematic Mapper multispectral images, which are two of the most commonly used images in geological and environmental studies based on remote sensing. Of the numerous techniques described for merging remote sensing image data, this paper analyses those based on Intensity-Hue-Saturation, Principal Component Analysis, Spherical Coordinates, High-Pass Filters and Colour Normalized transform, using SPOT panchromatic and Landsat TM data. The research goals were (1) to analyse and compare some of the most commonly used methods; (2) to select the most appropriate method for a detailed geological-environmental study, and (3) to apply the methodology to the Cabo de Gata-Níjar area, the site of one of the most distinctive natural parks in the country. Received: 29 November 1996 · Accepted: 29 July 1997  相似文献   

20.
The main task of this article is the evaluation of the IHS color transformation fusion, color composite ratios, and principal component analysis techniques for lithologic discrimination of the basement rocks exposed at Buwatah area, Western Arabian Shield, Saudi Arabia. Landsat ETM+ images were prepared and used to perform this task using PCI Geomatica software. IHS fusion technique was conducted through four main processing steps: (1) registration of the multispectral image (7, 4, and 2 in RGB) to the panchromatic image and then resample it to the same spatial resolution as that of the panchromatic image; (2) transformation of the three multispectral bands from RGB to IHS space; (3) substitution of the intensity value from the high spatial resolution panchromatic band; and finally (4) back transformation to RGB. The band ratios 5/7, 3/1, and 4/3 displayed in RGB, respectively, were used to produce the color composite ratio image. The first principal component (PC1), the second principal component (PC2), and the third principal component (PC3), displayed in RGB, respectively, were used to construct the color composite principal component image. The resultant images successfully discriminated the exposed rock units in the study area and a lithologic map has been constructed that is subjected to precise field verification. The stratigraphy of the area under consideration starts with metavolcanics and associated volcaniclastics as an oldest rock unit, followed by granodiorite–diorite, pink granite, biotite granite, acidic and basic dykes, and Cenozoic volcanics. A new rock unit (biotite granite) has been introduced that was not represented in previous mapping of the considered sector. The biotite granite is verified by field and petrographical studies.  相似文献   

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