Back to Search
Start Over
K-Ar AND 40Ar/39Ar GEOCHRONOLOGY OF WEATHERING PROCESSES.
- Source :
-
Annual Review of Earth & Planetary Sciences . 1999, Vol. 27 Issue 1, p183. 47p. - Publication Year :
- 1999
-
Abstract
- Recent developments in the application of K-Ar and [sup 40]Ar/[sup 39]Ar dating of continental weathering process demonstrate the method's suitability for dating minerals present in weathering profiles. Alunite-group sulfates and hollandite-group manganese oxides, which often precipitate through weathering reactions, were first analyzed by the K-Ar method 30 years ago. Recently these minerals were shown to be suitable to[sup 40]Ar/[sup 39]Ar geochronology, despite their fine-grained habits. The bulk nature of the K-Ar technique and the complex mineral assemblages in weathering profiles restrict K-Ar dating of weathering processes. The single-crystal approach possible with the[sup 40]Ar/[sup 39]Ar method allows the study of weathering profiles where alunite- and hollandite-group minerals occur as minor phases. Step-heating analysis possible with the[sup 40]Ar/[sup 39]Ar method provides information about the Ar and K retention histories, the presence of hypogene contaminants, and possible[sup 39]Ar recoil during sample irradiation. Fully automated, modern[sup 40]Ar/[sup 39]Ar systems enable analysis of several samples, providing a comprehensive weathering database. These results are useful in the study of continental paleoclimates and the geochemical, geomorphological, and tectonic histories of an area. [ABSTRACT FROM AUTHOR]
- Subjects :
- *CHEMICAL weathering
*ARGON
*GEOLOGICAL time scales
*PALEOCLIMATOLOGY
Subjects
Details
- Language :
- English
- ISSN :
- 00846597
- Volume :
- 27
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- Annual Review of Earth & Planetary Sciences
- Publication Type :
- Academic Journal
- Accession number :
- 5366109
- Full Text :
- https://doi.org/10.1146/annurev.earth.27.1.183