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geochemical analysis powerpoint

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geochemical analysis powerpoint

  1. 1. BILL MCFARLAND MENTOR: SCOTT BRAME CLEMSON EEES GEOLOGY RESEARCH FOREST MAPPING Geochemical Analysis of Sloped Site between Outcrops of Amphibolite and Mica Schist
  2. 2. Site Information Clemson Experimental Forest Outcrops are scarce Heavily forested Moderate Slope Bottom of slope: Amphibolite - Soil pH≈7.5 Top of Slope: Mica Schist - Soil pH≈ 5.5
  3. 3. Objectives  Characterize soil transitions between amphibolite and mica schist outcrops with no outcrops in between  Analyze borehole samples using hand methods and X- Ray Diffraction (XRD)  Assess whether geochemical and XRD analysis are reliable indicators of lithology for mapping
  4. 4. Core Sample Collection  AMS Soil Core Sampler Kit with Hammer Attachment  Collected cores on linear transect  Challenges  Compaction  Parent material http://www.forestry-suppliers.com/product_pages/Products.asp?mi=31181
  5. 5. pH Analysis  pH was determined using colorimetric technique  pH of borehole samples were taken  Technique  3-5 inches deep  Surface effects  reagents  Challenges  Colorimeter chart not precise  Removing organic/ surface material http://pecosales.com/product_pages/view_catalog_page.asp?id=3068
  6. 6. X-Ray Powder Diffraction  Technique used to study atomic spacing and crystal structures  Bragg’s law  nλ= 2dsinθ  Sensitivity  Software measurements  Sample preparation  Preparation  Grind  Sieve to powder- 53 micros  Properly prepare slides http://education.mrsec.wisc.edu/nanolab/F_center/index.html
  7. 7. Bragg’s Law  William Lawrence & William Henry Bragg  Nobel Prize in Physics  nλ= 2dsinθ  d=d-spacing  λ= wavelength of beam  n= integer  θ= incident angle  Each mineral has own unique signature  d-spacing allows identification  Reference patterns  XRD & PDXL basis  PDXL based on Bragg’s Law with knowledge of crystal structure
  8. 8. XRD & PDXL Usage  Initial XRD settings  θ=5-90°  y-axis= d-spacing intensity  x-axis= 2θ • PDXL Settings • Settings management • Composition identification • Element filtering • d-spacing intensities • Analytical justification
  9. 9. Sampling Arrangement Am MS 1 2 3 4 5 6 7
  10. 10. Transition Zone  Transition Zone  Boreholes 3-4  Color Characterization  Sudden change in soil color  pH Analysis  Substantial change in pH  Hand Sample Comparison  Weathering and minerals  XRD & PDXL Analysis  Strontium and hydroxamic acid
  11. 11. Manual Soil Analysis  Munsell color system characterization  Color identification  Hue: lightness  Chroma: color purity
  12. 12. pH Analysis  Amphibolite: pH≈7.5  Fe2+ ions  Mica Schist: pH≈5.5  Aluminum silicate  Garnetiferous  Ionic influences  Microorganisms  Weathering
  13. 13. BM3_1-2 Bm4_3-4 Transition Zone: Hand Sample Comparison Amphibolite Quartz Mica schist Muscovite Quartz
  14. 14. BM3: 1-2 ft. BM4: 3-4 ft. XRD Results for BM4
  15. 15. Strontium Hydroxamic Acid  Alkaline Earth Metal  Extreme Reactivity with oxygen and water  Intermediate to acidic pH  Strontium binds to soil particles by cation exchange  Organic compound dissolved from strontium  Known for chelation ability  Fe3+, Mg2+, Al3+ PDXL Analysis of BM4
  16. 16. BM5: 0-1 ft Bm6: 0-1 ft XRD Results from BM5
  17. 17. Conclusions  Transition zone identified between borehole sites 3-4 from hand sample and XRD analysis  Analysis of XRD signatures that is not a reliable method of outcrop transition because of inability to collect unweathered soil samples  At this site, the best method of lithology changes was from hand sample analysis
  18. 18. Special Thanks  Clemson University EEES Geology Research  Prof. Scott Brame  Victoria Sellers
  19. 19. Questions?

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