BILL MCFARLANDMENTOR: SCOTT BRAME

CLEMSON EEES GEOLOGY RESEARCHFOREST MAPPING

Geochemical Analysis of Sloped Site between Outcrops of

Amphibolite and Mica Schist

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

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

Core Sample Collection

AMS Soil Core Sampler Kit with Hammer Attachment

Collected cores on linear transect Challenges

Compaction Parent material

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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

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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

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

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

Sampling Arrangement

Am

MS

1

2

3

4

5

67

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

Manual Soil Analysis

Munsell color system characterization Color identification Hue: lightness Chroma: color purity

pH Analysis

Amphibolite: pH≈7.5 Fe2+ ions

Mica Schist: pH≈5.5 Aluminum silicate Garnetiferous

Ionic influences Microorganisms Weathering

BM3_1-2 Bm4_3-4

Transition Zone: Hand Sample Comparison

AmphiboliteQuartz

Mica schist MuscoviteQuartz

BM3: 1-2 ft. BM4: 3-4 ft.

XRD Results for BM4

Strontium Hydroxamic Acid

Alkaline Earth MetalExtreme Reactivity

with oxygen and waterIntermediate to acidic

pHStrontium binds to soil

particles by cation exchange

Organic compound dissolved from strontium

Known for chelation ability Fe3+, Mg2+, Al3+

PDXL Analysis of BM4

BM5: 0-1 ft Bm6: 0-1 ft

XRD Results from BM5

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

Special Thanks

Clemson University EEES Geology ResearchProf. Scott BrameVictoria Sellers

Questions?