J. Phys. IV France 104 (2003) 447
DOI: 10.1051/jp4:20030120

Effect of leaching on the crystallographic sites of trace metals associated with natural cements (site of Maqarin, Jordan): Case of Cr

J. Rose¹, N. Crouzet¹, L. Trotignon², S. Grimal¹, J. Susini³, H. Khoury⁴, E. Salameh⁴, A. Milodowski⁵ and F. Mercier<sup>6

1</sup>  CEREGE, Europole Méditerranéen de l'Arbois, BP. 80, 13545 Aix-en-Provence cedex 04, France
²  DED/SAMARA, bâtiment 307, CE-Cadarache, 13108 Saint-Paul-lez-Durance, France
³  ESRF, BP. 220, 38043 Grenoble cedex, France
⁴  Department of Geology and Mineralogy, University of Jordan, Amman, Jordan
⁵  Geochemistry, Mineralogy and Hydrogeology, British Geological Survey, Kingsley Dunham Center, Keyworth, Mottingham, U.K.
⁶  Université d'Evry, Evry, France

Abstract
This paper reports an investigation of the oxidation state of Cr in samples of natural cements formed 500 ky ago in Maqarin (Jordan). The analyses were conducted using the Scanning Microscope from the ID21 beamline at the ESRF (Grenoble-France) operated in fluorescence mode. Cr(III) and Cr(VI) maps are collected on these samples at a resolution of 1  m. The results suggest the slow oxidation of Cr(III) to Cr(VI) upon alteration of the cements in conditions of high pH and low to intermediate oxygen fugacity.

© EDP Sciences 2003