(Energy related studies utilizing K-feldspar thermochronology)

Technical Report · Wed Jan 01 00:00:00 EST 1992

DOI:https://doi.org/10.2172/5679668· OSTI ID:5679668

In our second year of current funding cycle, we have investigated the Ar diffusion properties and microstructures of K-feldspars and the application of domain theory to natural K-feldspars. We completed a combined TEM and argon diffusion study of the effect of laboratory heat treatment on the microstructure and kinetic properties of K-feldspar. We conclude in companion papers that, with one minor exception, no observable change in the diffusion behavior occurs during laboratory extraction procedures until significant fusion occurs at about 1100{degrees}C. The effect that is observed involves a correlation between the homogenization of cryptoperthite lamelle and the apparent increase in retentivity of about 5% of the argon in the K-feldspar under study. We can explain this effect of both as an artifact of the experiment or the loss of a diffusion boundary. Experiments are being considered to resolve this question. Refinements have been made to our experimental protocol that appears that greatly enhance the retrieval of multi-activation energies from K-feldspars. We have applied the multi-domain model to a variety of natural environments (Valles Caldera, Red River fault, Appalachian basin) with some surprising results. Detailed {sup 40}Ar/{sup 39} Ar coverage of the Red River shear zone, thought to be responsible for the accommodation of a significant fraction of the Indo-Asian convergence, strongly suggests that our technique can precisely date both the termination of ductile strike-slip motion and the initiation of normal faulting. Work has continued on improving our numerical codes for calculating thermal histories and the development of computer based graphing tools has significantly increased our productivity.

• 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: 5679668
• Report Number(s): DOE/ER/14049-3; ON: DE92007469
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
58 GEOSCIENCES
36 MATERIALS SCIENCE
ARGON
DIFFUSION
FELDSPARS
ISOTOPE DATING
ARGON 39
ARGON 40
HEAT TREATMENTS
MICROSTRUCTURE
PROGRESS REPORT
AGE ESTIMATION
ARGON ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CRYSTAL STRUCTURE
DOCUMENT TYPES
ELEMENTS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FLUIDS
GASES
ISOTOPES
LIGHT NUCLEI
MINERALS
NONMETALS
NUCLEI
RADIOISOTOPES
RARE GASES
SILICATE MINERALS
STABLE ISOTOPES
YEARS LIVING RADIOISOTOPES
020200* - Petroleum- Reserves
Geology
& Exploration
580000 - Geosciences
360602 - Other Materials- Structure & Phase Studies