Long-Term Evolution of the Martian Crust-Mantle System

Mars: a small terrestrial planet

“…Gamma ray or neutron spectroscopy was used to map concentration of several chemical species (e.g., H, Si, Cl, K, Fe, and Th in Boynton et al 2007, S in King and McLennan 2010) from orbit at the ∼500-km scale. Analytical tools sent to Mars on Rovers or landers and analyses of samples naturally brought naturally to Earth by impacts (i.e., martian meteorites) provide additional constraints on crustal chemistry and mineralogy (e.g., Rieder et al 1997 for Mars Pathfinder; Squyres et al 2006 andArvidson et al (2006) for the Mars Exploration Rovers; Boynton et al 2009 for the Phoenix lander, McLennan et al 2014 for the Curiosity Rover; Lodders 1998; Grott et al 2013 for a review of martian meteorites chemistry and mineralogy). However, this source of information is not necessarily representative of the bulk crust, and in particular, there is an obvious sampling bias when the young age of most of the Martian meteorites is compared with the distribution of ages of the rocks exposed at the surface.…”

“…On one hand, the surface of Mars is dominated by tholeiitic basalts composed of pyroxene, feldspar and olivine (McSween et al 2009;Grott et al 2013). Isotopic data on Martian meteorites suggest that crustal recycling, in contrast with the Earth, has been very limited on Mars (Halliday et al 2001).…”

“…Indeed, the evidence for a longterm evolution of the crust-mantle system suggests mantle or crust melting events associated with thermal anomalies or adiabatic decompression. Absence or limited convection would be also difficult to reconcile with evidence for progressive cooling of the interior (Ruiz et al 2011;Baratoux et al 2011;Grott et al 2013;Filiberto and Dasgupta 2015). Further work is, therefore, needed to reconcile the preservation of geochemical reservoirs with multiple pieces of evidence for the early and prolonged volcanic activity, involving large-scale convection in the mantle.…”

“…Estimates for crustal growth from surface exposure ages (inferred from crater counts) suggest that volcanic activity peaked in the Hesperian (Greeley and Schneid 1991b;Grott et al 2013), but the existence of such a peak should be taken with caution in light of the inherent difficulty in estimating the crustal production rate during the Noachian. The ubiquitous Hesperian volcanism (3-3.7 Gy) is manifested predominantly as broad plains (Syrtis Major Planum, Hesperia Planum and other Circum-Hellas volcanic provinces, typically reaching 10 6 km 2 in area) likely due to flood volcanism (analogous to lunar mare).…”

“…Although plate tectonics has been proposed to explain some characteristics of the Tharsis bulge (Courtillot et al 1975;Sleep 1994), it is now admitted that the crustmantle system has evolved in a stagnant-lid regime (one-plate planet) over most of its history (Golombek and Phillips 2009;Grott et al 2013), whereas the earliest period of Mars (<4.1 Gy) is still open to debate. The consequence is that the style of deformation observed at the surface is far different from those observed on Earth due to plate tectonics, with the Tharsis bulge playing a major role on the global shape and deformation observed, enabling large volcanoes to form in the absence of moving plates (e.g., Carr 1973).…”