Chapter 8 · Low-Temperature Minerals, Exclusive of Carbonates

Answers · Sharp, Principles of Stable Isotope Geochemistry, 1st ed. (2007) · ← Problems

Answer 1

  1. From Figure 8.12 and the definition of α, the oxygen value is α18O(kaolinite–water) ≈ 1.027. reconstructed For hydrogen, substituting into the definition of α gives a value of 0.97 (as printed). [The printed oxygen value is lost in the extraction; 1.027 corresponds to the ≈+27‰ kaolinite–water offset of the kaolinite line (constructed).]
  2. Not printed in the extraction. check vs print

Answer 2

For hydrogen isotopes, there is no constant input value as there is for oxygen (i.e., atmospheric oxygen). Therefore the slope should be 1.

Answer 3

Using Longinelli’s equation, and because the δ18O value of the water is constant, the effect on t(°C) of changing the phosphate value follows directly from the equation’s slope. If we change δ18O by 2.9‰, we change the temperature by ≈12.5 °C. reconstructed [The printed equation and final value are lost in the extraction; with T = 111.4 − 4.3·(δp − δw), ΔT = 4.3 × 2.9 = 12.5 °C (constructed).]

Answer 4

For pigs and humans, the relationships are given by equations (8.2) and (8.3), respectively (where C is a constant). Equation (8.7) gives the general relationship. If the carbohydrate combines with atmospheric O2 to give CO2 and H2O in equilibrium with each other, then two-thirds of the oxygen comes from the air. The final relationship is lost in the extraction. check vs print

Answer 5

The difference in delta values is related to the animals’ different diets. Apparently, kangaroo rats eat only C3 plants, whereas other rodents eat either C3 or C4 plants, depending upon availability. Most likely, kangaroo rats stash seeds from the winter months.

Answer 6

Because water concentrates the heavy isotope of hydrogen, but the light isotope of oxygen, relative to clay minerals.

Transcribed from Z. Sharp, Principles of Stable Isotope Geochemistry, 1st ed. (Pearson Prentice Hall, 2007), end-of-chapter problem set (published source). Reference-scale names are written VSMOW, VPDB and VCDT where the original used SMOW, PDB and CDT, with the original numerical constants unchanged; historical usages (e.g. Craig's definition of SMOW) are kept as printed.

The source PDF's text layer scrambles mathematics, so equations and some values were reconstructed during transcription. Bracketed notes and anything tagged reconstructed or check vs print are editorial (constructed), not part of the original, and the warn-tagged items should be verified against the print copy.