Relative Burial Depths of Nakhlites: An Update

Nakhlites are augite-rich cumulate rocks with variable amounts of olivine and groundmass plus minor Fe, Ti oxides [e.g., 1]. Our previous studies revealed that nakhlites showed correlated petrography and mineralogy that could be explained by different locations (burial depths) in a common cooling cumulate pile [e.g., 2]. We so far analyzed six of the seven currently known nakhlites, Nakhla (Nak), Governador Valadares (GV), Lafayette (Laf), NWA817, Y000593 (Y) and MIL03346 (MIL) [e.g., 2,3] and calculated cooling rates of four nakhlites (Nak, GV, Laf, and NWA817) by using chemical zoning of olivine [e.g., 4]. In this abstract, we complete our examination of petrographic and mineralogical variation of all currently known nakhlites by adding petrology and mineralogy of NWA998. We also report results of cooling calculations for Y, MIL and NWA998. Then, we update our model of the nakhlite igneous body in terms of relative burial depth of each sample.