Energy related studies utilizing K-feldspar thermochronology

Technical Report · Fri Jan 01 00:00:00 EST 1993

DOI:https://doi.org/10.2172/6874523· OSTI ID:6874523

Two distinct sources of information are available from a [sup 40]Ar/[sup 39]Ar step-heating experiment: the age spectrum and Arrhenius plot. Model ages are calculated from the flux of radiogenic argon ([sup 40]Ar*) (assuming trapped argon of atmospheric composition) relative to the reactor produced [sup 39]Ar evolved during discrete laboratory heating steps. With the additional assumption that the [sup 39]Ar is uniformly distributed within the sample, we can infer the spatial distribution of the daughter product. ne associated Arrhenius plot, derived by plotting the diffusion coefficient (obtained from the inversion of the 39[sup Ar] release function assuming a single domain) against the inverse temperature of laboratory heating, are a convolution of the parameters which characterize the individual diffusion domains (whether these be dictated by varying length scale, energetics, etc.). However, many and perhaps Most [sup 40]Ar/[sup 39]Ar age spectra for slowly cooled alkali feldspars are significantly different from model age spectra calculated assuming a single diffusion-domain size. In addition, Arrhenius plots calculated from the measured loss of [sup 39]Ar during the step heating experiment show departures from linearity that are inconsistent with diffusion from domains of equal size. By extending the single diffusion-domain closure model (Dodsontype) to apply to minerals with a discrete distribution of domain sizes, we obtained an internally consistent explanation for the commonly observed features of alkali feldspar age spectra and their associated Arrhenius plots.

• Research Organization: Univ. of California, Los Angeles, CA (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: FG03-89ER14049
• OSTI ID: 6874523
• Report Number(s): DOE/ER/14049-4; ON: DE93013137
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
EARTH CRUST
TEMPERATURE MEASUREMENT
HISTORICAL ASPECTS
AGE ESTIMATION
ARGON 39
ARGON 40
ARRHENIUS EQUATION
FELDSPARS
PROGRESS REPORT
ARGON ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
DOCUMENT TYPES
EQUATIONS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
ISOTOPES
LIGHT NUCLEI
MINERALS
NUCLEI
RADIOISOTOPES
SILICATE MINERALS
STABLE ISOTOPES
YEARS LIVING RADIOISOTOPES
580000* - Geosciences