Comparative analysis of the geochemistry and mineral chemistry of BIR OUNANE 005 with lunar materials returned by the Apollo, Luna and Chang’e missions. Evaluation of compositional affinities and posible lithological source reservoirs.
Year: 2026
Type: preprint
Abstract: Bir Ounane 005 is an officially classified lunar meteorite described as a polymict regolith breccia composed of lithic clasts and millimetre-sized mineral fragments within a fine-grained matrix. Recognised components include anorthosites, basalts, noritic anorthosites, norites, Fe-rich clasts and impact melts, together with zoned pyroxene, fayalitic olivine, pleonaste-type spinel, silica, calcium phosphates and troilite. This study compares the mineral chemistry of Bir Ounane 005 with the geochemical and mineralogical characteristics of lunar samples returned by the Apollo, Luna, Chang’e-5 and Chang’e-6 missions, in order to identify compositional affinities that may constrain its possible source reservoirs. The available data indicate that Bir Ounane 005 cannot be interpreted as representing a single magmatic reservoir. Its broad compositional dispersion, particularly in olivine and pyroxene, together with the coexistence of anorthosite, norite and basalt, demonstrates the incorporation of petrogenetically distinct materials. The feldspathic component shows strong affinity with highland materials from Apollo 16, Luna 20 and Chang’e-6, whereas some pyroxene populations closely resemble those of Chang’e-6 mare basalts and, to a lesser extent, Chang’e-5. The coexistence of highly magnesian and highly ferroan olivine further supports mixing between materials of different origins and evolutionary histories. Among the returned collections examined, Chang’e-6 provides the most complete compositional and lithological analogue for Bir Ounane 005, combining mare basalt with anorthositic, noritic and magnesian components within a single regolith. This similarity does not establish a direct origin in the South Pole–Aitken or Apollo basins, but it defines a geochemical provenance hypothesis that can be experimentally tested.
Author: Jose Garcia
Language: English
Topic: Astro and Planetary Science
Subfield: Space and Planetary Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7213438356