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PhD candidate studying the interplay of modern technology and traditional field techniques.

PINBOARD SUMMARY

Multi-spectral imagery has allowed for geologic mapping and exploration to be performed in the lab.

Traditionally, geologic mapping has been performed by traversing the region of interest on foot and recording the orientations and types of rock exposed. While this is still a indispensable aspect of geology it becomes less than ideal when the area being mapped is very remote, rugged, or otherwise difficult to explore. Remote sensing is term which refers to any technique with which we can acquire information of an area without being at that location. The most well known remote sensing technique is the classification of a surface, most commonly the Earth's surface, using multi-spectral imagery. This allows for the user to map out an area based on just the images without physically being there.

The term multi-spectral images refer to those images which contain information from multiple wavelengths along the electromagnetic spectrum. The data recorded for each wavelength is stored in what is referred to as a "band" of the image. In the case of a simple color image there are three bands consisting of red, green, and blue. Combing these bands in creates full color image. When referring to multi-spectral imagery information is recorded from wavelengths other than visible light, for example, infrared or ultraviolet. This increases the number of bands in the image to more than the three contained in a traditional image, the LANDSAT satellite system produces seven band multi-spectral images for example.

The key to using the information contained in the types of images described above is understanding that any surface absorbs and reflects certain wavelengths giving the surface a specific "spectral signature". For example, an apple absorbs most of the visible light spectrum and reflects the wavelength associated with red. Bringing this process back to geologic mapping we can identify rock types based on what wavelengths they absorb. This is determined by there mineralogy, grain size, etc. The spectral signatures of minerals are known and this can be used to identify the rock types, however, it is preferable to have stations in the map area with a known rock type which can be used to confirm the spectral data.

This pinboard focuses on the methods discussed above in a number of settings which range from the targets of the mining to the lunar surface. It is important to consider that this technology not only allows for better geologic mapping here on Earth but is also our primary way of understanding the makeup of distant planets.

9 ITEMS PINNED

Mapping of Neoproterozoic source rocks of the Huqf Supergroup in the Sultanate of Oman using remote sensing

Abstract: In recent years, the Neoproterozoic Huqf Supergroup formations of the Oman Salt Basins have been the target for oil exploration. The present study maps the surficial exposure of the Huqf Supergroup in and around Khufai Dome of the Huqf area in the Sultanate of Oman using low-cost multi-spectral remotely sensed satellite data and image processing methods such as decorrelation stretching, principal component analysis (PCA) and spectral angle mapper (SAM), as alternative to expensive and time-consuming tools, which have the capability and potential to be used by geoscientists for oil exploration. In this research, the study of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) spectral bands 8, 3 and 1 by decorrelation stretching well discriminated the Masirah Bay, the Khufai, the Shuram and the Buah Formations of the Nafun Group, the source rocks of Huqf Supergroup with the Quaternary deposits. The analysis of visible and near infrared–shortwave infrared spectral bands of ASTER by PCA clearly showed the occurrence and spatial distribution of such formations in the RGB principal component images (R:PC1, G:PC2, B:PC3). The spatial distributions of such formations are assessed by confusion matrix after using maximum likelihood (ML), spectral angle mapper (SAM) and spectral information divergence (SID) algorithms. The matrix of ML algorithm has provided the best overall accuracy of 92.93% and kappa coefficient of 0.92. The minerals of the formations were detected by SAM. Further, the detection of such mineral groups was confirmed through the ASTER thermal infrared (TIR) spectral indices image developed using the carbonate index (CI), quartz index (QI), and mafic index (MI). All results of image analyses are evaluated in the field and laboratory studies. The study also evaluates the satellite data and image processing methods for the formations of Jabal Akhdar, the equivalent formations of the Khufai Dome, to show the sensor capability and the use of the image processing methods to study the source rocks. The results of the study provided similar discriminations comparable to the Khufai Dome. Therefore, the data and the techniques are recommended to the exploration geologists for use in similar regions of the world.

Pub.: 09 Apr '16, Pinned: 13 Apr '17

Remote sensing and GIS prospectivity mapping for magmatic-hydrothermal base- and precious-metal deposits in the Honghai district, China

Abstract: In this paper, we constructed an exploration target model for volcanogenic massive sulfide and hydrothermal deposits in Honghai district (China) using moderate resolution ETM+, ASTER, and hyperspectral Hyperion images and high resolution ZY-3 images, and weights-of-evidence (WofE) analysis and concentration-area (C-A) fractal modeling. The methodology and mapping steps were: (1) ETM + images were used to extract hydroxyl and iron-oxide alterations for identification of linear and ring fault structures and prospective zones in regional scale; (2) ASTER images were used to extract SiO2 index, kaolinite, chlorite, propylite, potassium, carbonate, and limonite alterations for identification of mineralization zones in district scale; (3) hyperspectral Hyperion images were analyzed to identify mineral components for identification of Cu<img border="0" alt="single bond" src="http://cdn.els-cdn.com/sd/entities/sbnd" class="glyphImg">Au deposit zones in district scale; (4) high resolution ZY-3 images were used to extract geological objects (e.g., volcanic rocks, integration, and linear and ring fault structures) and cross-validate multiple type alterations and their associations with lithological strata based on interpretation of ETM+ and ASTER images; (5) alteration/structural factors and geological objects were integrated for mineral prospectivity mapping by WofE analysis, and mineral prospectivity was classified by (C-A) fractal modeling. Ring faults, iron-oxide alteration, chlorite alteration and silicification are important exploration factors, whereas carbonate alteration, potassic alteration, and linear faults are secondary exploration factors. Ten exploration targets were recognized in the Honghai district.

Pub.: 05 Jul '16, Pinned: 13 Apr '17

High resolution multispectral satellite data interpretation and limited ground checking: A proxy for geological mapping and uranium exploration in Mahakoshal Fold Belt of Son valley area, Madhya Pradesh

Abstract: Abstract This research aims at integrating remote sensing data and field studies to prospect for uranium mineralisation in the Palaeoproterozoic Mahakoshal Group of rocks in the Son valley area, Central India. In present work, a revised geological map of Mahakoshal Fold Belt (MFB) bounded by Son-Narmada north fault (SNNF) and Son-Narmada south fault (SNSF) along Chorhut-Sidhi-Chitrangi sector falling in Sidhi, Rewa and Shahdol districts of Madhya Pradesh has been prepared based on interpretation of digitally enhanced satellite images. The satellite image interpretation is supported by limited field works, radioelemental measurements (eU, eTh and % K) of in-situ rocks by four channel Portable Gamma Ray Spectrometer (PGRS) and existing published geological maps of Geological Survey of India. In search for mineral potential areas, accurate and up-to-date geological maps are essential as it represent the most basic information for carrying out further exploration activities. However, available geological maps of MFB and sedimentary formations ofVindhayan Supergroup along SNNF and Chhotanagpur Granite Gneissic Complex (CGGC) and Gondwana Supergroup along SNSF available in public domain are discontinuous and multi-scaled. Optical bands of Landsat Enhanced Thematic Mapper Plus (ETM+) and Indian Remote Sensing (IRS) PAN of the study area were used in mapping lithological units, structural features and small intrusive bodies. Principal Component Analysis (PCA), Image Fusion, Linear Contrast Stretch, Histogram Equalisation and False Color Composite (FCC) of various band combination and ratio maps were performed in the digital image processing of geo-rectified satellite imageries. In analyzing and interpreting high resolution multi-spectral images, certain standard norms were employed to acquire information about litho-structural features such as topographic, geomorphic and tectonic facets. The main criteria are colour and tones, geomorphology, drainage patterns and vegetation anomalies. The processed Landsat ETM+ images were interpreted and classified to delineate detailed lithological units and structural features in order to update existing geological maps. To validate the prepared litho-structural map, ground survey was carried out along critical geological sections for checking the geological features like rocks, folds, faults, fractures and foliations. While comparing with the ground geological data to that obtained from the satellite imagery, it is observed that remote sensing interpreted litho-structural map is in a class with the ground observations. Various data sets such as unconformable geological contacts, fault breccias zone, lineaments and gamma ray spectrometric data (eU, eTh and % K) based on PGRS study were integrated and modelled using Geographical Information System (GIS) for identifying important prospective horizons for uranium mineralisation in the MFB of Son valley area. It is concluded that the revised large scale geological map is of practical use for not only for mapping of litho-structural architecture, but also in identifying potential areas for ‘vein–type’ uranium mineralisation along the structurally deformed zones of the SNNF, Asmi-Jiawan fault (AJF) and SNSF; and ‘unconformity- type’ of uranium mineralisation in the outliers of Jungel Group. The revised map and radiometric data acquired are useful in formulating exploration strategy for the ongoing uranium exploration in this areaAbstractThis research aims at integrating remote sensing data and field studies to prospect for uranium mineralisation in the Palaeoproterozoic Mahakoshal Group of rocks in the Son valley area, Central India. In present work, a revised geological map of Mahakoshal Fold Belt (MFB) bounded by Son-Narmada north fault (SNNF) and Son-Narmada south fault (SNSF) along Chorhut-Sidhi-Chitrangi sector falling in Sidhi, Rewa and Shahdol districts of Madhya Pradesh has been prepared based on interpretation of digitally enhanced satellite images. The satellite image interpretation is supported by limited field works, radioelemental measurements (eU, eTh and % K) of in-situ rocks by four channel Portable Gamma Ray Spectrometer (PGRS) and existing published geological maps of Geological Survey of India. In search for mineral potential areas, accurate and up-to-date geological maps are essential as it represent the most basic information for carrying out further exploration activities. However, available geological maps of MFB and sedimentary formations ofVindhayan Supergroup along SNNF and Chhotanagpur Granite Gneissic Complex (CGGC) and Gondwana Supergroup along SNSF available in public domain are discontinuous and multi-scaled.Optical bands of Landsat Enhanced Thematic Mapper Plus (ETM+) and Indian Remote Sensing (IRS) PAN of the study area were used in mapping lithological units, structural features and small intrusive bodies. Principal Component Analysis (PCA), Image Fusion, Linear Contrast Stretch, Histogram Equalisation and False Color Composite (FCC) of various band combination and ratio maps were performed in the digital image processing of geo-rectified satellite imageries. In analyzing and interpreting high resolution multi-spectral images, certain standard norms were employed to acquire information about litho-structural features such as topographic, geomorphic and tectonic facets. The main criteria are colour and tones, geomorphology, drainage patterns and vegetation anomalies. The processed Landsat ETM+ images were interpreted and classified to delineate detailed lithological units and structural features in order to update existing geological maps.+To validate the prepared litho-structural map, ground survey was carried out along critical geological sections for checking the geological features like rocks, folds, faults, fractures and foliations. While comparing with the ground geological data to that obtained from the satellite imagery, it is observed that remote sensing interpreted litho-structural map is in a class with the ground observations. Various data sets such as unconformable geological contacts, fault breccias zone, lineaments and gamma ray spectrometric data (eU, eTh and % K) based on PGRS study were integrated and modelled using Geographical Information System (GIS) for identifying important prospective horizons for uranium mineralisation in the MFB of Son valley area. It is concluded that the revised large scale geological map is of practical use for not only for mapping of litho-structural architecture, but also in identifying potential areas for ‘vein–type’ uranium mineralisation along the structurally deformed zones of the SNNF, Asmi-Jiawan fault (AJF) and SNSF; and ‘unconformity- type’ of uranium mineralisation in the outliers of Jungel Group. The revised map and radiometric data acquired are useful in formulating exploration strategy for the ongoing uranium exploration in this area

Pub.: 01 Aug '16, Pinned: 13 Apr '17

Fusing ASTER and QuickBird-2 Satellite Data for Detailed Investigation of Porphyry Copper Deposits Using PCA; Case Study of Naysian Deposit, Iran

Abstract: Hydrothermal alteration mineral zones associated with porphyry copper mineralization can be identified and discriminated based on distinctive spectral properties of the ASTER satellite data. Image processing techniques are mostly used for regional scale mapping but in this study, we aimed to evaluate them for more detailed exploration studies by fusing ASTER and QuickBird-2 satellite data using Gram-Schmidt sharpening method to enhance the spatial resolution of the imagery. Selective principal component analysis (PCA) technique is used to provide mineral distribution maps from the spatially improved ASTER data. PCA was applied to ASTER bands with the objective of mapping the occurrence of mineral end-members related to a porphyry copper deposit named Naysian in Iran. The results illustrate the ability of ASTER data for extracting information on alteration minerals which are valuable for mineral exploration studies and support the role of PCA as a very robust image processing technique for that purpose. The spatial distribution of hydrothermal alteration zones has been verified by insitu field observations. This investigation indicated that applying image processing techniques has a great ability to obtain significant and comprehensive information in detailed stages of porphyry copper deposit exploration at a local scale. The results of this research can assist exploration geologists to make a better planning for more detailed stages of exploring porphyry copper and even gold deposits in other virgin regions before costly detailed ground investigations. Consequently, the introduced image processing approach can present an optimum idea about the application of remote sensing in final stages of mineral exploration. Hydrothermal alteration mineral zones associated with porphyry copper mineralization can be identified and discriminated based on distinctive spectral properties of the ASTER satellite data. Image processing techniques are mostly used for regional scale mapping but in this study, we aimed to evaluate them for more detailed exploration studies by fusing ASTER and QuickBird-2 satellite data using Gram-Schmidt sharpening method to enhance the spatial resolution of the imagery. Selective principal component analysis (PCA) technique is used to provide mineral distribution maps from the spatially improved ASTER data. PCA was applied to ASTER bands with the objective of mapping the occurrence of mineral end-members related to a porphyry copper deposit named Naysian in Iran. The results illustrate the ability of ASTER data for extracting information on alteration minerals which are valuable for mineral exploration studies and support the role of PCA as a very robust image processing technique for that purpose. The spatial distribution of hydrothermal alteration zones has been verified by insitu field observations. This investigation indicated that applying image processing techniques has a great ability to obtain significant and comprehensive information in detailed stages of porphyry copper deposit exploration at a local scale. The results of this research can assist exploration geologists to make a better planning for more detailed stages of exploring porphyry copper and even gold deposits in other virgin regions before costly detailed ground investigations. Consequently, the introduced image processing approach can present an optimum idea about the application of remote sensing in final stages of mineral exploration.

Pub.: 01 Aug '16, Pinned: 13 Apr '17

Geosciences, Vol. 6, Pages 36: Identification of Multi-Style Hydrothermal Alteration Using Integrated Compositional and Topographic Remote Sensing Datasets

Abstract: The western part of the island of Milos, Greece has undergone widespread, intense alteration associated with a range of mineralization, including seafloor Mn-Fe-Ba, sub seafloor Pb-Zn-Ag, and epithermal Au-Ag. The surrounding country rocks are a mixture of submarine and subaerial calc-alkaline volcanic rocks ranging from basaltic andesite to rhyolite in composition, but are predominantly andesites and dacites. The current surface spatial distribution of the alteration mineralogy is a function not only of the original hydrothermal, but also subsequent tectonic and erosional processes. The high relief and the excellent rock exposure provide ideal conditions to evaluate the potential of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite remote sensing data to identify and differentiate the different styles of alteration mineralisation. Laboratory spectral reflectance and calculated emittance measurements of field samples, supported by XRD analysis and field mapping, were used to support the analysis. Band ratio and spectral matching techniques were applied to the shortwave-infrared (SWIR) reflectance and thermal-infrared (TIR) emissivity imagery separately and were then integrated with topographic data. The band ratio and spectral matching approaches produced similar results in both the SWIR and TIR imagery. In the SWIR imagery, the advanced argillic, argillic and hydrous silica alteration zones were clearly identifiable, while in the TIR imagery, the silicic and advanced argillic alteration zones, along with the country rock, were differentiable. The integrated mineralogical–topographic datasets provided an enhanced understanding of the spatial and altitude distribution of the alteration zones when combined with conceptual models of their genesis, which provides a methodology for the differentiation of the multiple styles of alteration.

Pub.: 29 Jul '16, Pinned: 13 Apr '17

Application of ASTER remote sensing data to geological mapping of basement domains in arid regions: a case study from the Central Anti-Atlas, Iguerda inlier, Morocco

Abstract: Satellite remote sensing is shown to provide critical support for geological and structural mapping in semiarid and arid areas. In this work, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data were used to clarify the geological framework of the Precambrian basement of the Iguerda Proterozoic inlier in the Moroccan Central Anti-Atlas. In this study, the interpretation of the processed digital data has been ground truthed with geological field data collected during a reconnaissance-mapping program in the Central Anti-Atlas. The Iguerda inlier offers a deeply eroded Precambrian massif dominated by a Paleoproterozoic basement composed of supracrustal metasedimentary units intruded by various Eburnian granitoids. Impressive mafic dyke swarms mainly of Proterozoic age crosscut this basement. Eburnian basement rocks are unconformably overlain by Lower Ediacaran volcanosedimentary rocks of the Ouarzazate Group and Upper Ediacaran–Lower Cambrian carbonates. The applied ASTER analyses are particularly effective in the lithological differentiation and discrimination of geological units of the Iguerda inlier. The spectral information divergence (SID) classification algorithm coupled with spectral angle mapper and maximum likelihood classification effectively discriminates between metamorphic rocks, granitoid bodies, and carbonate cover. SID classification improves geologic map accuracy with respect to the spatial distribution of plutonic bodies and metamorphic units. In addition, Paleoproterozoic granitoids have been well discriminated into separate distinct suites of porphyritic granites, granodiorites, and peraluminous leucogranite suites. This discrimination was initially identified via remote sensing analysis and later ground truthed in the field. This methodology enhances geological mapping and illustrates the potential of ASTER data to serve as a vital tool in detailed geologic mapping and exploration of well-exposed basement of arid regions, such as the Proterozoic of the Anti-Atlas Mountains of Morocco.

Pub.: 16 May '13, Pinned: 13 Apr '17