The crystal-chemical basis for Ar retention in micas: inferences from interlayer partitioning and implications for geochronology
Article Abstract:
The crystal-chemical analysis of micas shows that (super 40)Ar retention is less in biotite than in muscovite. The partitioning behavior of biotite and muscovite shows that the weaker interlayer bonding in biotite is due to spacious interlayer volume and fewer interlayer bonds per unit cell. Muscovite gives a more favorable electrostatic environment for Ba(super 2+) substitution than biotite. The interlayer ionic porosity affects the loss of radiogenic isotopes. The partitioning/porosity studies help geochronological predictions.
Publication Name: Contributions to Mineralogy and Petrology
Subject: Earth sciences
ISSN: 0010-7999
Year: 1996
User Contributions:
Comment about this article or add new information about this topic:
Multipath diffusion in geochronology
Article Abstract:
Ion and laser microprobe analytical tools reveal spatial distributions of radiogenic isotopes in minerals not detected by simple volume diffusion. A numerical model for solving coupled multi-path diffusion equations, which describe simultaneous diffusion of a solute species through the crystal lattice and high-diffusivity pathways under non-steady conditions, has been developed. Adding a radioactive source term to the equations provides lower integrated cooling ages and closure temperatures.
Publication Name: Contributions to Mineralogy and Petrology
Subject: Earth sciences
ISSN: 0010-7999
Year: 1995
User Contributions:
Comment about this article or add new information about this topic:
(super 40)Ar-(super 39)Ar and Rb-Sr geochronology of high-pressure metamorphism and exhumation history of the Tavsanli Zone, NW, Turkey
Article Abstract:
An analysis of the metamorphism of argon is presented, focusing on problems created by excess argon. Topics include techniques of geochronology, uncovering the history of high-pressure low-temperature rocks, and use of infrared lasers to analyze phengite grains.
Publication Name: Contributions to Mineralogy and Petrology
Subject: Earth sciences
ISSN: 0010-7999
Year: 1999
User Contributions:
Comment about this article or add new information about this topic:
- Abstracts: Morphotectonic evolution of rifted continental margins: inferences from a coupled tectonic-surface processes model and fission track thermochronology
- Abstracts: Early Jurassic deformation in the Pine Forest Range, northwest Nevada, and implications for Cordilleran tectonics
- Abstracts: Multiphase inclusions in plagioclase from anorthosites in the Stillwater Complex, Montana: implications for the origin of the anorthosites
- Abstracts: Remagnetization of Cretaceous forearc strata on Santa Margarita and Magdalena Islands, Baja California Sur: implications for northward transport along the California margin
- Abstracts: Nitrogen-rich fluid in the upper mantle: fluid inclusions in spinel dunite from Lanzarote, Canary Islands. Sr-Nd-Pb isotope data for ultramafic xenoliths from Hierro, Canary Islands: melt infiltration processes in the upper mantle