Cosmic ray produced 10Be and 26Al in Antarctic rocks: exposure and erosion history
Abstract
We have measured cosmic ray produced ( t1/2 = 1.5 million years) 10Be and ( t1/2 = 0.705 million years) 26Al in purified quartz fractions of selected rock samples from Antarctic mountains. From these data we calculate (1) mean erosion rates, for the limiting case of steady-state surface exposure to cosmic rays, and (2) minimum exposure ages, for the limiting case of no erosion. Calculated mean erosion rates are very low, on the order of a few times 10 -5 cm/yr; we believe the sampling to be sufficient to generalize this result to exposed bedrock in Antarctica. In favorable cases it is possible to distinguish between the limiting cases: steady-state erosion seems a better description in such cases. Most samples, including some taken a few meters above the present ice level, seem to have been exposed for millions of years, without major episodes of burial or abrasion by ice.
- Publication:
-
Earth and Planetary Science Letters
- Pub Date:
- June 1991
- DOI:
- 10.1016/0012-821X(91)90221-3
- Bibcode:
- 1991E&PSL.104..440N
- Keywords:
-
- Antarctic Regions;
- Cosmic Rays;
- Geochronology;
- Isotope Separation;
- Radiochemistry;
- Trace Elements;
- Aluminum Isotopes;
- Beryllium Isotopes;
- Erosion;
- Ice Environments;
- Quartz;
- Rocks