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Title: (Energy related studies utilizing K-feldspar thermochronology)

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 formore » 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.« less
Publication Date:
OSTI Identifier:
5679668
Report Number(s):
DOE/ER/14049-3
ON: DE92007469
DOE Contract Number:
FG03-89ER14049
Resource Type:
Technical Report
Research Org:
California Univ., Los Angeles, CA (United States)
Sponsoring Org:
DOE; USDOE, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
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