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. 2021 Aug 6;7(32):eabh2687. doi: 10.1126/sciadv.abh2687

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Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).

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Fig. 3 — The upward increasing trends of Al₂O₃ and SiO₂ with constant TiO₂ (A) and the upward decreasing trends of MgO/Al₂O₃, P₂O₅/Al₂O₃ and Zn/Al₂O ratios strongly indicate chemical weathering and leaching (B). The upward decreasing Fe₂O₃/Al₂O₃ ratios suggest separation of Fe from Al. Chemical data from nodules, pebbles, and sulfates are excluded. Gray lines indicate the average values of Mars’ crust.