Quaternary continental weathering geochronology by laser-heating Ar-40/Ar-39 analysis of supergene cryptomelane

Citation
Yx. Feng et P. Vasconcelos, Quaternary continental weathering geochronology by laser-heating Ar-40/Ar-39 analysis of supergene cryptomelane, GEOLOGY, 29(7), 2001, pp. 635-638
Citations number
27
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Journal title
GEOLOGY
ISSN journal
0091-7613 → ACNP
Volume
29
Issue
7
Year of publication
2001
Pages
635 - 638
Database
ISI
SICI code
0091-7613(200107)29:7<635:QCWGBL>2.0.ZU;2-W
Abstract
Incremental laser-heating analyses of supergene cryptomelane clusters extra cted from three distinct weathering profiles from the Mary Valley region, s outheast Queensland, Australia, yield reproducible and well-defined plateau ages ranging from 346 +/- 15 to 291 +/- 14 ka (2 a). Precipitation of supe rgene cryptomelane in this period implies that relative humid climate preva iled in southeast Queensland from 340 to 290 ha, a result consistent with o xygen isotope analyses of marine sediments from Ocean Drilling Program Site 820 and with regional pollen and spore records. These results, the first r eport on the precise Ar-40/Ar-39 dating of Quaternary supergene cryptomelan e, indicate that Ar-40/Ar-39 analysis of pedogenic minerals provides a reli able geochronometer for the study of Quaternary surficial processes useful in the study of soil formation rates, continental paleoclimates, and archae ological sites devoid of datable volcanic minerals.