Journal article
Magmatic complexity on early Mars as seen through a combination of orbital, in-situ and meteorite data
Lithos, Vol.254-255, pp.36-52
06/2016
DOI: 10.1016/j.lithos.2016.02.023
Abstract
Until recently, Mars was considered a basalt-covered world, but this vision is evolving thanks to new orbital, in situ and meteorite observations, in particular of rocks of the ancient Noachian period. In this contribution we summarise newly recognised compositional and mineralogical differences between older and more recent rocks, and explore the geodynamic implications of these new findings. For example the MSL rover has discovered abundant felsic rocks close to the landing site coming from the wall of Gale crater ranging from alkali basalt to trachyte. In addition, the recently discovered Martian regolith breccia NWA 7034 (and paired samples) contain many coarse-grained noritic-monzonitic clasts demonstrably Noachian in age, and even some clasts that plot in the mugearite field. Olivine is also conspicuously lacking in these ancient samples, in contrast to later Hesperian rocks. The alkali-suite requires low-degree melting of the Martian mantle at low pressure, whereas the later Hesperian magmatism would appear to be produced by higher mantle temperatures. Various scenarios are proposed to explain these observations, including different styles of magmatic activity (i.e. passive upwelling vs. hotspots). A second petrological suite of increasing interest involves quartzo-feldspathic materials that were first inferred from orbit, in local patches in the southern highlands and in the lower units of Valles Marineris. However, identification of felsic rocks from orbit is limited by the low detectability of feldspar in the near infrared. On the other hand, the MSL rover has described the texture, mineralogy and composition of felsic rocks in Gale crater that are granodiorite-like samples akin to terrestrial TTG (Tonalite–Trondhjemite–Granodiorite suites). These observations, and the low average density of the highlands crust, suggest the early formation of ‘continental’ crust on Mars, although the details of the geodynamic scenario and the importance of volatiles in their generation are aspects that require further work.
•Rocks of early Mars are showing an ever increasing diversity in composition.•Existence of an alkaline suite, which was never observed before.•Evidences of low-degree melting of the Martian mantle at low pressure.•Plutonic granodiorite-like samples in Gale Crater akin to terrestrial TTG•In its early history some form of ‘continental’ crust was produced on Mars.
Details
- Title: Subtitle
- Magmatic complexity on early Mars as seen through a combination of orbital, in-situ and meteorite data
- Creators
- Violaine Sautter - IMPMC, Muséum d'Histoire Naturelle de Paris, FranceMichael J. Toplis - Research Institute in Astrophysics and PlanetologyPierre Beck - Institut de Planétologie et d'Astrophysique de GrenobleNicolas Mangold - LPG Nantes, FranceRoger Wiens - Los Alamos National LaboratoryPatrick Pinet - Research Institute in Astrophysics and PlanetologyAgnes Cousin - Research Institute in Astrophysics and PlanetologySylvestre Maurice - Research Institute in Astrophysics and PlanetologyLaetitia LeDeit - LPG Nantes, FranceRoger Hewins - IMPMC, Muséum d'Histoire Naturelle de Paris, FranceOlivier Gasnault - Research Institute in Astrophysics and PlanetologyCathy Quantin - Claude Bernard University Lyon 1Olivier Forni - Research Institute in Astrophysics and PlanetologyHorton Newsom - Institute of Meteoritics, Albuquerque, NM, USAPierre-Yves Meslin - Research Institute in Astrophysics and PlanetologyJames Wray - Georgia Institute of TechnologyNathan Bridges - Johns Hopkins University Applied Physics LaboratoryValérie Payré - G2R, Nancy, FranceWilliam Rapin - Research Institute in Astrophysics and PlanetologyStéphane Le Mouélic - LPG Nantes, France
- Resource Type
- Journal article
- Publication Details
- Lithos, Vol.254-255, pp.36-52
- Publisher
- Elsevier B.V
- DOI
- 10.1016/j.lithos.2016.02.023
- ISSN
- 0024-4937
- eISSN
- 1872-6143
- Grant note
- name: NASA's Mars exploration programme; DOI: 10.13039/501100002830, name: CNES
- Language
- English
- Date published
- 06/2016
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984294924402771
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