Elemental Distribution in the Light Mineral Isolate of Soil Separates1
- L. R. Drees and
- L. P. Wilding2
The light mineral isolate (specific gravity < 2.89) was quantitatively separated from the 50–250µm, 20–50µm, and 5–20µm fractions of selected A and B soil horizons derived from loess and outwash deposits. Elemental Ti, Zr, Fe, K, and Ca were determined by X-ray spectroscopy both on total and light mineral isolates. More than 75% of Ti, Zr, Fe, and Ca occurs in the light mineral isolates of the 5–20µm fraction while the 50–250µm light mineral isolate contains 25 to 70% of these elements. With the exception of K, there is a progressive concentration of above elements as particle-size decreases. Essentially 100% of the K occurs in the light mineral isolate independent of particle-size. The concentration of Ti and Zr is greater than can be accounted for by mineral grain counts in the light isolate. Little or no co-association of Fe with Ti, Zr, Ca, or K could be established in secondary Fe-oxide grain coatings. It is concluded that much of the Ti, Zr, and Fe concentrated in the light mineral isolates occurs as micro-inclusions of accessory minerals within primary host minerals such as quartz and feldspars. Caution must be exercised in allocating elemental percentages of a given size fraction to specific detrital minerals.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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