Using cosmogenic isotopes to measure basin-scale rates of erosion

Conference · Wed Jan 01 00:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5763853

Bierman, P R; Steig, E ^[1]

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1. Univ. of Washington, Seattle, WA (United States). Dept. of Geology

The authors present a new and different approach to interpreting the abundance of in situ-produced cosmogenic nuclides such as [sup 36]Cl, [sup 26]Al, and [sup 10]Be. Unlike most existing models, which are appropriate for evaluating isotope concentrations on bedrock surfaces, this model can be used to interpret isotope concentration in fluvial sediment. Because sediment is a mixture of material derived from the entire drainage basin, measured isotope abundances can be used to estimate spatially-averaged rates of erosion and sediment transport. Their approach has the potential to provide geomorphologists with a relatively simple but powerful means by which to constrain rates of landscape evolution. The model considers the flux of cosmogenic isotopes into and out of various reservoirs. Implicit in model development are the assumptions that a geomorphic steady-state has been reached and that sampled sediment is spatially and temporally representative of all sediment leaving the basin. Each year, the impinging cosmic-ray flux produces a certain quantity of cosmogenic isotopes in the rock and soil of a drainage basin. For a basin in steady state, the outgoing isotope flux is also constant. They solve for the rate of mass loss as a function of isotope abundance in the sediment, the cosmic ray attenuation length, the isotope half life, and the effective isotope production rate. There are only a few published measurements of cosmogenic isotope abundance in sediment. They calculated model denudation rates for sediment samples from Zaire and central Texas. The denudation rates they calculated appear reasonable and are similar to those they have measured directly on granite landforms in Georgia and southeastern California and those calculated for the Appalachian Piedmont.

• OSTI ID: 5763853
• Report Number(s): CONF-921058-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
WATERSHEDS
EROSION
ABUNDANCE
ALUMINIUM 26
BERYLLIUM 10
CHLORINE 36
COSMIC RADIATION
ENVIRONMENTAL TRANSPORT
EXPERIMENTAL DATA
GEOLOGIC MODELS
GEOMORPHOLOGY
IRRADIATION
SEDIMENTS
TRACER TECHNIQUES
ALKALINE EARTH ISOTOPES
ALUMINIUM ISOTOPES
BERYLLIUM ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
CHLORINE ISOTOPES
DATA
ELECTRON CAPTURE RADIOISOTOPES
EVEN-EVEN NUCLEI
GEOLOGY
INFORMATION
IONIZING RADIATIONS
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MASS TRANSFER
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
RADIATIONS
RADIOISOTOPES
SECONDS LIVING RADIOISOTOPES
YEARS LIVING RADIOISOTOPES
540211* - Environment
Terrestrial- Basic Studies- Radiometric Techniques- (1990-)