The Brac/Dourbes Olivine‐Cumulate Rock, Séítah Formation, Jezero Crater Floor, Mars: Its Parent Magma, and Relation to Basalts of the Máaz Formation

Creators: Treiman, Allan H.¹; Hernández‐Montenegro, Juan D.²; Wiens, Roger C.³; Wade, Larry⁴; VanBommel, Scott⁵; Van Beek, Jason⁴; Udry, Arya⁶; Tice, Mike M.⁷; Schmidt, Mariek E.⁸; Moore, Kelsey²; Liu, Yang⁴; Lawson, Peter⁴; Knight, Abigail⁵; Klevang, David Arge⁹; Kizovski, Tanya⁸; Jones, Michael M. W.¹⁰; Hurowitz, Joel A.¹¹; Hodyss, Robert⁴; Henneke, Jesper⁹; Flannery, David¹⁰; Denise, Robert⁴; Debaille, Vinciane¹²; Cable, Morgan L.⁴; Brown, Adrian¹³; Beyssac, Olivier¹⁴; Asimow, Paul²; Allwood, Abigail C.⁴

1. Lunar and Planetary Institute
2. California Institute of Technology
3. Purdue University West Lafayette
4. Jet Propulsion Lab
5. Washington University in St. Louis
6. University of Nevada, Las Vegas
7. Texas A&M University
8. Brock University
9. Technical University of Denmark
10. Queensland University of Technology
11. Stony Brook University
12. Université Libre de Bruxelles
13. Agile Decision Sciences, Huntsville, AL, USA
14. Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS, Sorbonne Université, Muséum National d'Histoire Naturelle, Paris, France

Abstract

The Mars 2020 rover, Perseverance, encountered a range of basaltic igneous rocks on the floor of Jezero crater, two of which are olivine cumulates, formed by accumulation of olivine crystals from basaltic magma. These olivine cumulates lie in a geomorphically distinct region, named Séítah, on the Jezero crater floor. To understand the origin of the olivine cumulates and their relationship with the adjacent basalts of the Máaz formation, we calculated the composition of the parent magma of one of the olivine cumulates, named Brac, based on chemical analyses and mineralogic interpretations from the Planetary Instrument for X-ray Lithochemistry (PIXL) instrument. Acceptable Brac/Dourbes parent magmas are olivine tholeiite basalts with SiO₂ ∼ 45%, MgO ∼ 8%, FeO_Tot ∼ 27%, Al₂O₃ ∼ 6%, and total alkali oxides of ∼2.8% weight. These compositions are similar to one of the Máaz basalts, the rock Rimplas, which is stratigraphically close to Séítah, but chemically distinct from other Máaz basalts. Rimplas could (within uncertainty) be a sample of the Brac parent magma, but it is more likely that Rimplas and Brac had a common (or similar) parent magma. Geochemical similarities between Rimplas and the other Máaz basalts thus suggest that Brac (and other olivine-rich rocks of Séítah) and the Máaz basalts could be geochemically related; they could have been cogenetic and possibly contemporaneous, or could have been derived (at different times) from similar or related mantle source(s).

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Acknowledgement

This work would have been impossible without the combined efforts of the Mars 2020 engineering and science teams, and we gratefully acknowledge the incredible efforts involved in designing the spacecraft and its instruments, flying them to Mars, safely landing them, and operating them efficiently in a hostile environment. We are grateful to K. Hollocher for writing and sharing the code “norm4.xlsx” and to P. Tol for creating and distributing color schemes designed for people with visual distinctions. The work described here was partially carried out at the Jet Propulsion laboratory, California Institute of Technology under prime contract with the National Aeronautics and Space Administration (80NM0018D0004); this Grant supported authors A.C.A, J.A.H., M.T., Y.L., A.H.T, L.W, J.V.B., M.M.T., K.M., P.L., R.H., R.D., and M.L.C. J.D.H.M. acknowledges support from a grant from the Fulbright Foundation and the Caltech Center for Comparative Planetary Evolution. J.A.H. also supported by JPL Subcontract #1529702. S.VB., A.K., and A.U. were supported by the Mars 2020 Participating Science Program, Grant 80NSSC21K0328. M.E.S. and T.K. were supported by the Canadian Space Agency (CSA) M2020 Participating Scientist Program, Grant 21EXPMAPS CSA 2021. R.C.W was supported in part by NASA Grant NNH13ZDA0180. O.B. was supported by CNES, France. V.D. was supported by Fonds de la Recherche Scientifique (F.R.S.-FNRS), Belgium. The Lunar and Planetary Institute (LPI) is operated by Universities Space Research Association (USRA) under cooperative agreements with the Science Mission Directorate of NASA. This paper was benefitted from reviews by A. Ostwald and an anonymous critic. Lunar and Planetary Institute contribution # 3xxx.

Data Availability

PIXL X-ray spectra and derived chemical compositions are available through the NASA Planetary Data System (PDS), Geosciences Node, in the PIXL raw and processed data bundle, urn:nasa:pds:mars2020_pixl: Allwood and Hurowitz (2021). Supporting Information S1 is deposited with Figshare.com at (Treiman et al., 2025)—https://doi.org/10.6084/m9.figshare.28677437.

Supplemental Material

Supporting Information S1: 2024JE008539-sup-0001-Supporting Information SI-S01.docx

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The files will be made publicly available on October 24, 2025.

Reason: journal policy

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Resource type: Journal Article
Publisher: American Geophysical Union
Published in: Journal of Geophysical Research: Planets, 130(4), e2024JE008539, ISSN: 2169-9097.
Languages: English