Constraints on the depth and thermal vigor of melting in the Martian mantle

Abstract

Studies of rocks in Gale Crater and clasts within the Martian meteorite breccia Northwest Africa (NWA) 7034 (and paired stones) have expanded our knowledge of the diversity of igneous rocks that make up the Martian crust beyond those compositions exhibited in the meteorite collection or analyzed at any other landing site. Therefore, the magmas that gave rise to these rocks may have been generated at significantly different conditions in the Martian mantle than those derived from previously studied rocks. Here we build upon our previous models of basalt formation based on rocks analyzed in Gusev Crater and Meridiani Planum to the new models of basalt formation for compositions from Gale Crater and a clast in meteorite NWA 7034. Estimates for the mantle potential temperature, T P based on Noachian age rock analyses in Gale Crater, Gusev Crater, and Bounce Rock in Meridiani Planum, and a vitrophyre clast in NWA 7034 are within error, which suggests that the calculated average T P of 1450 ± 70°C may represent an average global mantle temperature during the Noachian. The T P estimates for the Hesperian and Amazonian, based on orbital analyses of the chemistry of the crust, are lower in temperature than our estimates for the Noachian, which is consistent with simple convective cooling of the interior of Mars. However, the T P estimates from the young meteorites are significantly higher than the estimates based on surface chemistry and are consistent with localized "hot spot" melting and not heating up of the interior.

Present-day heat flow model of Mars

“…A limited influence of secular cooling through post-Noachian times is consistent with evidence for a liquid core existing at present50, recent abundant volcanism51 and limited global contraction52; limited secular cooling might also be consistent with high-temperature shergottite5354, although this class of meteorites might have originated in mantle-plume settings unrepresentative of background mantle55. (For a review of the evidence for limited secular cooling see ref.…”

The effects of mantle composition on the peridotite solidus: Implications for the magmatic history of Mars

“…The martian meteorites appear to be depleted in aluminum (or plagioclase), sodium, potassium, and thorium relative to both in-situ measurements of rocks and soils of materials at the Gusev, Meridiani, Gale, and Mars Pathfinder landing sites and with orbital gamma ray spectrometer and near-infrared spectroscopy observations (McSween et al, 2009;Poulet et al, 2009;Treiman and Filiberto, 2015). These differences in magma composition may reflect temporal changes in the water content, oxidation state, or temperature of the mantle over time (Balta and McSween, 2013;Baratoux et al, 2013;Tuff et al, 2013;Filiberto and Dasgupta, 2015). It is now well established that the martian mantle is isotopically heterogeneous, with three well-defined reservoirs.…”

The early heat loss evolution of Mars and their implications for internal and environmental history

“…I add here that recent petrologic modeling121314 of magma production finds higher potential mantle temperature for magmas originating shergottite meteorites (which typically have ages younger than 0.6 Ga) than for magmas originating Gusev and Meridiani basaltic rocks, which are Noachian in age. (This period corresponds to ages older than 3.7 Ga, and was followed by the Hesperian; e.g., Ref.…”