The {sup 36}Cl-{sup 36}Cl method for determining both the exposure time and erosion rate of surface rocks
- Purdue Univ., West Lafayette, IN (United States)
Chlorine-36 is produced by interaction of galactic cosmic-rays with rocks on the surface of the Earth through two different types of nuclear reactions. Spallation of Ca and K produces {sup 36}Cl with an exponential decrease with depth. Thermal and epi-thermal neutron activation of {sup 35}Cl has a depth profile that first increases with depth, reaches a peak at about 65 g/cm2 (about 25 cm in granite) then decreases exponentially at depths below 100 g/cm2. Because of this opposite dependence on depth near the surface, the ratio of production from spallation to that from neutron activation in a single surface sample is a sensitive measure of erosion and soil/snow/tree cover. Production by spallation is an excellent means for determining exposure time after correction for erosion. Methods for determining both the spallation and neutron activation components of {sup 36}Cl using low-Cl and high-Cl mineral separates and their application to determining exposure age and erosion history will be presented.
- OSTI ID:
- 126663
- Report Number(s):
- CONF-950402--
- Country of Publication:
- United States
- Language:
- English
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