Dating of weathering profiles by radioactive disequilibria: contribution of the study of authigenic mineral fractions

被引：31

作者：

Dequincey, O

Chabaux, F

Clauer, N

Liewig, N

Muller, JP

机构：

[1] CNRS ULP, Ctr Geochim Surface, Eost, F-67084 Strasbourg, France

[2] IRD, Unite Rech Geosci Environm Trop, F-93143 Bondy, France

来源：

COMPTES RENDUS DE L ACADEMIE DES SCIENCES SERIE II FASCICULE A-SCIENCES DE LA TERRE ET DES PLANETES | 1999年 / 328卷 / 10期

关键词：

weathering profile; laterite; geochronology; radioactive disequilibrium; Rb-Sr;

D O I：

10.1016/S1251-8050(99)80177-3

中图分类号：

P [天文学、地球科学];

学科分类号：

07 ;

摘要：

Soil isotopic dating is important for understanding mass transfers related to rock weathering. Here we evaluate a method including TIMS analyses of (U-234/U-238) activity ratios on < 0.2 mu m fractions of a Cameroon laterite. Variations of the (U-234/U-238) ratios with depth show (1) significant (U-234/U-238) disequilibrium at the bottom of the pedological units, and (2) progressive returns towards secular equilibrium above. These results suggest that U fractionation occurs at the base of the units and that the analysed fractions probably evolve as closed/restricted systems within each unit. From these data, an overall age of 1.5 Ma may be proposed for the development of this laterite. ((C) Academie des sciences / Elsevier, Paris.).

引用

页码：679 / 685

页数：7

共 26 条

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[Anonymous], [No title captured]

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