241-7 Post-Shield Mantle Plume Lavas From Mars: The Nakhlites

Session: Petrology, Volcanology, and Mantle Plumes across the Solar System, Part I

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Many volcanos on Mars and Venus are morphologically comparable to terrestrial volcanos above mantle plumes. This similarity extends to chemistry and petrology – the nakhlite martian meteorites are like some post-shield magmas above Earth plumes.

Nakhlites are augite-rich igneous rocks [1,2], most of which represent magma compositions [3]. They crystallized at ~1.35 Ga [4], and are enriched in incompatible elements [2]. Had the nakhlites formed on Earth, they would be called ankaramites [5,6].

The nakhlites’ young ages restrict their source to a few central volcanoes, inferred to represent mantle plumes [7]; most of Mars’ basaltic surfaces are > ~3.0 Ga [8]. The impact crater that launched the nakhlites off Mars must appear fresh – nakhlites cosmic ray exposure ages are only ~11 Ma [9]. A likely source crater is Kotka, on the flanks of the Elysium volcano [10], which represents a long-lived (and active [11]) mantle plume.

On Earth, plume shield lavas are typically tholeiitic and un- to slightly-enriched in incompatible elements [12]. Post-shield lavas are distinct, being enriched in incompatibles [13] and commonly in augite [14,15], and were derived from long-term depleted sources [13]. Nakhlite lavas fit this model, and also have elevated Nb/Y [5,7] which is (on Earth) characteristic of ‘rejuvenated’ post-shield plume lavas. Thus, mantle plumes on Earth and Mars share some similar magmatic products, and must also share similar mantle compositions and structures.

[1] Treiman A.H. (2005) Geochemistry 65, 203-270. [2] Udry A. & Day J.M.D. (2018) Geochim. Cosmochim. Acta 238, 292-315. [3] Treiman A.H. (2025) LPSC 56, abstract 1472. [4] Cohen B.E. et al. (2017) Nature Comm. 8, 640. [5] Ostwald A. et al. (2024) Geochim. Cosmochim. Acta 380, 1-17. [6] https://www.alexstrekeisen.it/english/vulc/ankaramite.php. [7] Day J.M.D. et al. (2018) Nature Comm. 9, 4799. [8] Carr M.H. & Head J.W. (2010) Earth Planet. Sci. Lett. 294, 185–203. [9] Nyquist, L.E. et al (2001) Space Sci. Rev. 96, 105–164. [10] Herd C.D. et al. (2024) Science Advances 10, eadn2378. [11] Broquet A. & Andrews-Hanna J.C. (2023) Nature Astronomy 7, 160-169. [12] White W.M. (2010) Ann. Rev. Earth Planet. Sci. 38:133–60. [13] Harrison L.N. et al. (2024) Contrib. Mineral. Petrol. 179:9. [14] Hammer J. et al. (2016) Contrib. Mineral. Petrol. 171, 1-23. [15] Klügel A. et al. (2017) Jour. Petrol. 58, 1227-1248.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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