|
|||||
|
|
An unsuccessful attempt at U/Th dating of soil calcretes from the Doukkâli area (western Morocco) and environmental implications |
|
| Authors: | M Branca U Masi M Voltaggio |
| Institution: | aCNR, Istituto di Geologia Ambientale e Geoingegneria, via Bolognola 7, Rome I-00138, Italy bDipartimento di Scienze della Terra, Università di Roma “La Sapienza”, Piazzale A.Moro 5, Rome I-00185, Italy |
| Abstract: | A large number of calcrete samples from topsoils of the Doukkâli area, western Morocco, were studied by U-disequilibrium series methods. The 230Th/234U ages are rather uniformly distributed between>350 and 2 ka BP. Homologous samples for occurrence and structure display quite different ages, the 230Th/234U ages are considered apparent. This is explained by repeated deposition of secondary calcite in the calcrete pores, which caused lowering of the original ages. However, the apparent ages may be considered minimum ages of the calcrete formation, indicating that calcium carbonate mobilization and deposition has been taking place repeatedly since >350 ka. The age range obtained is quite comparable with that of calcretes from southern Spain, suggesting similar conditions for the calcrete formation in the two areas. |
| Keywords: | U/Th dating Calcretes Doukkâli Western Morocco |
| 本文献已被 ScienceDirect 等数据库收录！ | |