The age of the martian meteorite Northwest Africa 1195 and the differentiation history of the shergottites

Abstract

sources. This suggests that the oldest group of meteorites is more closely related to one another than they are to the younger meteorites that are derived from less incompatible-element-depleted sources. Closed-system fractional crystallization of this suite of meteorites is modeled with the MELTS algorithm using the bulk composition of Yamato 980459 as a parent. These models reproduce many of the major element and mineralogical variations observed in the suite. In 2 addition, the rare-earth element systematics of these meteorites are reproduced by fractional crystallization using the proportions of phases and extents of crystallization that are calculated by MELTS. The combined effects of source composition and fractional crystallization are therefore likely to account for the major element, trace element, and isotopic diversity of all shergottites.Thus, assimilation of a martian crustal component is not required to explain the geochemical diversity of the shergottites.

The evolution of a heterogeneous Martian mantle: Clues from K, P, Ti, Cr, and Ni variations in Gusev basalts and shergottite meteorites

“…Fractional crystallization of primary shergottitic magma may generate major and REE variations among the older shergottites (474 Ma to 575 Ma; Dar al Gani 476, Sayh al Uhaymir 005/008, and Dhofar 019) as demonstrated by Symes et al (2008). Using the MELTS algorithm (Ghiorso and Sack, 1995), these workers found that 43% crystallization of spinel, olivine, orthopyroxene, pigeonite, clinopyroxene, and plagioclase of Y98 magma can generate compositions similar to the more evolved QUE94201.…”

Science Priorities for Mars Sample Return

“…MSR (e.g. McPherson et al, 2001; Wadhwa, 2001;Borg et al, 2003;Symes et al, 2008;Shearer et al, 2008) and subsequent evolution of the crust, mantle, and core (e.g. Treiman, 1990;Shearer et al, 2008).…”

Oxygen Isotope Thermometry of DaG 476 and SaU 008 Martian Meteorites: Implications for Their Origin

“…These mafic to ultramafic rocks provide unique samples that can be used to decipher and understand the magmatic processes and the crystallization history of Mars [5,6]. Based on the crystallization ages of SNCs (150-4500 Ma) obtained from various geochronometers such as Sm-Nd, Rb-Sr, Pb-Pb, and Ar-Ar [7][8][9][10][11][12][13][14][15][16][17], it appears that the Martian magmatism extended over most of the solar system history that agrees well with the time span of crater retention ages [18]. It is believed that shergottites-the most abundant of the Martian meteorites found to date-have been generated by the partial melting of the Martian mantle [8,19]; therefore, their geochemical signatures can provide insights into the Martian mantle chemistry.…”

“…These meteorites are related via identical ejection ages (i.e., mean ejection age = 1.1 ± 0.2 Ma; N = 11) and compositionally identical mantle source [17]. There is no physical evidence that could suggest that these rocks are derived from the same terrain on Mars [15]. However, the majority of the depleted shergottites share similar ejection ages (1.1 ± 0.2 Ma; [17], except NWA 5990, NWA 7032, QUE 94201 (3 Ma) and Dhofar 019 (18 Ma), suggesting that most of them might have launched in a single impact probably from a similar terrain.…”

“…In order to understand the magma generation in the Martian interior and its eruption mechanism, several models based on numerical and geochemical data were proposed [15,22,[37][38][39]. Geochemical models regarding the source regions of the shergottites suggest that these regions have formed either as a result of solidification of a Martian magma ocean [7,8,40,41] or by the interaction between mantle and crustal reservoirs [20,42].…”