Remote sensing and Reflectance spectroscopy as useful tools for Uranium exploration

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1 Remote sensing and Reflectance spectroscopy as useful tools for Uranium exploration Fares Howari, PhD University of Texas at Austin Bureau of Economic Geology (BEG) and Center for International Energy and Environmental Policy (CIEEP)

2 WHAT ARE THE OBJECTIVES IN EXPLORATION? First 10 slides adapted from Virginia McLemore; New Mexico Bureau u of Geology and Mineral Resource

3 WHAT ARE THE OBJECTIVES IN EXPLORATION? Establish baseline/background conditions Find alteration zones Find ore body Determine if ore can be mined or leached Determine if ore can be processed Determine ore reserves Locate areas for infrastructure/operations Environmental assessment Further understand uranium deposits Refine exploration models

4 STEPS Define uranium deposit model Select area Collect and interpret regional data Define local target area Field reconnaissance Drilling (Reconnaissance) Ore discovery Imgp2995.mov

6 Select Area How do we select an area to look for uranium?

7 Select Area How do we select an area to look for uranium? Areas of known production Areas of known uranium occurrences Favorable conditions for uranium

8 COLLECT DATA Historical data Government surveys University research programs Archives Company reports Web sites Published literature Prospectors

9 Methods Magnetic surveys Electromagnetic (EM), electromagnetic sounding Direct current (DC) GPR (Ground penetrating radar potential) Seismic Time-domain electromagnetic (TEM) Controlled source audio- magnetotellurics (CSAMT) Radiometric surveys Induced polarization (IP) Spontaneous potential (SP) Borehole geophysics Satellite imagery Imagery spectrometry ASTER (Advanced space- borne thermal emissions reflection radiometer) AVIRIS SWIR Multispectral

10 REMOTE SENSING

SATELLITE LANDSAT AIRBORNE Remote sensing is the science of remotely

earth s s surface and recording interactions between matter and

HYPERSPECTRAL GROUND Field Spectrometer Alumbrera, Ar Data is

11 SATELLITE LANDSAT AIRBORNE Remote sensing is the science of remotely acquiring, processing and interpreting spectral information about the earth s s surface and recording interactions between matter and electromagnetic energy. HYPERSPECTRAL GROUND Field Spectrometer Alumbrera, Ar Data is collected from satellite and airborne sensors. It is then calibrated and verified using a field spectrometer. CUPRITE, NV Goldfield, NV

Sunlight Interaction with the Atmosphere and the Earth s s Surface Data is collected by special detector arrays.

ELECTROMAGNETIC SPECTRUM Natural objects are generally not perfect reflectors, and therefore the intensity of the reflection

These interactions of absorption and reflection form the basis of spectroscopy and hyperspectral analysis.

12 Sunlight Interaction with the Atmosphere and the Earth s s Surface Data is collected by special detector arrays. Collection is done at different spectral and spatial resolutions depending on the type of sensor. ELECTROMAGNETIC SPECTRUM Natural objects are generally not perfect reflectors, and therefore the intensity of the reflection varies as some of the energy is absorbed by the earth and not reflected back to the sensor. These interactions of absorption and reflection form the basis of spectroscopy and hyperspectral analysis. Each spatial element is called a pixel. Pixel size varies from 1/2 meters in some hyperspectral sensors to 30 meters in Landsat and ASTER, which are multispectral. Sensor spatial differences and band configurations are shown below. Source: Bob Agars

13 Reflected and Emitted Energy UV BLUE GREEN RED NIR SWIR MWIR LWIR What you see is not what you get!

14 Imaging Spectroscopy WHAT IS IMAGING SPECTROSCOPY? Imaging spectroscopy is a a new tool that can be used to map specific materials by detecting specific chemical bonds. As a result it is an excellent tool for environmental assessments, and for mineral mapping and exploration. The premier imaging spectrometer is the NASA/JPL AVIRIS system, covering a 10.5 km swath with 17- meter pixel spacing. AVIRIS collects data at a rate of 2 square kilometers per second!

15 Other Hyperspectral Platforms Canadian Compact Airborne Spectrographic Imager-2 2 (CASI-2) NASA Terra Moderate Resolution Imaging Spectrometer (MODIS; corse spatial resolution) NASA Earth Observer Advanced Land Imager (ALI) AISA; and GER 3700 (ground-based)

16 AISA Hyperspectral System AISA Hyperspectral System is an airborne hyperspectral sensor designed to provide timely, accurate and reliable information on the Earth s surface in commercial and scientific applications.

17 GER 3700

18 So What Does HSI Look Like?

19 Hyperspectral Imagery Before Processing Hyperspectral Imagery Before Hyperspectral Imagery Before Processing Processing

20 How does Spectral profile and spectral classes extracted from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) look like after processing?

21 An image cube An image cube is a technique used to show hyperspectral spatial data, by using a three-dimensional Figure. The x and y values are those of the spatial data, and the z value is formed by the accumulation of spectral layers. Along the edges of this cube, depending on where you slice it, you can see the spectra of the edge pixels represented continuously. In order to visualize different areas, you can slice the image cube differently. If you need a simpler technique, you can select three particular bands and show them as color composites for display

wavelength can be used to make a coherent image (data cube).

22 HYPERSPECTRAL IMAGING SPECTROSCOPY Imaging spectroscopy is a technique for obtaining a spectrum in each position of a large array of spatial positions so that any one spectral wavelength can be used to make a coherent image (data cube). Source: CSIRO The major difference from Landsat is the ability to detect individual mineral species and differentiate vegetation species.

23 Hyperspectral Sensing Flight Line Intensity Pixel Spectrum Single Pixel Wavelength Spatial Pixels Spectral Bands Series of Sensor Frames Single Sensor Frame

24 1 2 3

25 + Literature! Spectral Library

27 Extraction of U mining wastes spectra

28 Mineral identification

29 Airborne 1. Radiometrics : Measure of natural radiation in the Earth s surface. 2. Also Known as Gamma- Ray Spectrometry. 3. Who uses it?- Geologists and Geophysicists. 4. Also useful for studying geomorphology and soils.

30 Radioactivity 1. Process in which, unstable atom becomes stable through the process of decay of its nucleus. 2.Energy is released in the form of radiation; (a) Alpha Particle - Least Energy- Travels few cm of air. (b) Beta Particle (or electrons)- Higher Energy- Travels upto a meter in air (c) Gamma Rays- Highest Energy- Travels upto 300 meters in air.

31 Radioactivity (Contd.) 3. Energy of Gamma Ray is characteristic of the radioactive element it came from. 4. Gamma Rays are stopped by water and other molecules (soil & Rock). 5. A radiometric survey measures the spatial distribution of three radioactive elements; (a) Potassium (b)thorium (c) Uranium

32 Process 1. How we do radiometric survey?- By measuring the energy of Gamma Rays. 2. Can be measure on the ground or by a low flying aircraft. 3. Gamma Rays are detected by Spectrometer. 4. Spectrometer- Counts the number of times each Gamma Ray of particular energy intersects it.

33 Process 5. The energy spectrum measured by a spectrometer is in MeV. 6. Range- 0 to 3 MeV. 7. The number of Gamma Ray counts across the whole spectrum is referred as the total count (TC).

34 Process Energy of Gamma Rays Number of Gamma Rays (per second) High Low

35 Surface Sampling/ ground truthing The soil sample pit at the site 41E10T3, Finland. The alluvial horizons at the floodplain sediment sampling site 29E05F3, France.

36 Some Minerals Associated with Uranium Uraninite (UO2) Pitchblende (U2O5.UO3 or U3O8) Carnotite (uranium potassium vanadate) Davidite-brannerite brannerite-absiteabsite type uranium titanates Euxenite-fergusonite fergusonite-smarskitesmarskite group Secondary Minerals: Gummite Autunite Saleeite Torbernite Coffinite Uranophane Sklodowskite (Lambert et al., 1996)

37 GEOCHEMICAL SAMPLING Ground water Surface water Stream sediments Soils Biological Ore samples Radon Track etch (identify radiaoactivity)

38 Sampling from Seepage/Spr ing Sampling from Well Sampling from Stream Sampling from Hand Pump Pictures from Pakistan Atomic Energy Agency

39 Sampling from Spring Sampling from Lined Well Sampling from Stream Pond

40 Sampling from Bore Hole Preparation of water Samples for Analyses

41 Perennial Stream STREAM SEDIMENTS SAMPLING

42 Thanks!

HYPERSPECTRAL IMAGING

1 HYPERSPECTRAL IMAGING Lecture 9 Multispectral Vs. Hyperspectral 2 The term hyperspectral usually refers to an instrument whose spectral bands are constrained to the region of solar illumination, i.e.,