Bulk chemistry of Saharan shergottite Dar al Gani 476

We report on major and trace element analyses obtained by, respectively, in ductively coupled plasma-atomic emission spectrometry (ICP-AES) and inducti vely coupled plasma-mass spectrornetry (ICP-MS) of three different aliquots of the new Saharan shergottite Dar al Gani (DaG) 476. The new analyses are in excellent agreement with previous data (Zipfel et al., 2000). Ba, Sr an d U abundances, together with the presence of carbonate, suggest that the s ample has been significantly weathered. Three rare earth element (REE) patt erns (normalized to CI) determined on three different aliquots of the sampl e all show similar shapes. The heavy REEs are flat with a slight depletion at the heavy end and a strong depletion from Dy to Pr. All of the patterns display an upturn to La which we interpret as being caused by the introduct ion of a terrestrial component. Taking the terrestrial contamination into a ccount, this study demonstrates that DaG 476 is one of the most depleted of the shergottites, and, just like Queen Alexandra Range (QUE) 94201 (Dreibu s et al., 1996), displays very low Zr/Hf ratios. It appears that the Zr/Hf ratios of shergottites are not uniform, and have been significantly fractio nated by martian mantle processes.