Petrology and chemistry of the Picritic Shergottite North West Africa 1068 (NWA 1068)

Barrat, Jean‐Alix; Jambon, Albert; Bohn, Marcel; Gillet, Ph.; Sautter, V.; Göpel, C.; Lesourd, M.; Keller, Francine

doi:10.1016/s0016-7037(02)00934-1

Cited by 118 publications

(170 citation statements)

References 47 publications

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“…A specific petrogenesis should account for the lower Ti content of the titanomagnetites of these four compared to the other basaltic shergottites, where paramagnetic high-Ti titanomagnetite is usually reported as ulvöspinel. Until now, we have used the "basaltic shergottite" category in a broad sense (following Treiman 1998 andMcSween 2002), i.e., including the "olivine-phyric" (or "picritic") and "basaltic" stricto sensu categories (according to Goodrich 2002 andBarrat et al 2002b). However, it is worth noting that the titanomagnetite-bearing cases are encountered only in the basaltic stricto sensu category (except NWA 2046), while all olivine-phyric (except NWA 2046) and the majority of basaltic stricto sensu shergottites have their saturation remanence controlled by pyrrhotite.…”

Section: Magnetic Mineralogy Of Martian Rocksmentioning

confidence: 99%

“…Here the origin of SNC magnetism will be discussed using an already published reappraisal that includes all desert finds up to the year 2000 (Rochette et al 2001), together with the original data on all ANSMET Antarctic meteorites as well as the more recent Saharan finds: the NWA 817 and 998 nakhlites and the basaltic shergottites Dho 378 (Ikeda et al 2002), NWA 480/1460, 856, 1068/1183/ 1775, 1195, 1669, and 2046(Barrat et al 2002a, 2002bJambon et al 2002Jambon et al , 2003. Magnetic mineralogy data were implemented by a comprehensive petrographic data set on sulfide modal abundances and sulfide composition on nine samples (Lorand et al Forthcoming).…”

Section: Introductionmentioning

confidence: 99%

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Matching Martian crustal magnetization and magnetic properties of Martian meteorites

Rochette

Gattacceca

Chevrier

et al. 2005

Meteoritics &Amp; Planetary Science

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Section: Magnetic Mineralogy Of Martian Rocksmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Matching Martian crustal magnetization and magnetic properties of Martian meteorites

Rochette

Gattacceca

Chevrier

et al. 2005

Meteoritics &Amp; Planetary Science

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“…Meteorite(s) Lodders (1998) Shergotty, Zagami, ALH A77005, LEW 88516, EET A79001 A, EET A79001 B, Nakhla, Chassigny, Lafayette Barrat et al (2002a) DaG 476, Shergotty, Zagami Rubin et al (2000) Los Angeles Mikouchi et al (1996), Dreibus et al (1996), Warren and Kallemeyn (1997), Kring et al (2003) QUE 94201 Barrat et al (2002b) NWA 1068 Jambon et al (2002) NWA 856, Los Angeles Dreibus et al (2002) SaU 005 Taylor et al (2002) Dhofar 019…”

Section: Appendixmentioning

confidence: 99%

Chemical compositions of martian basalts (shergottites): Some inferences on b; formation, mantle metasomatism, and differentiation in Mars

Treiman

2003

Meteorit & Planetary Scien

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Abstract-Bulk chemical compositions of the shergottite basalts provide important constraints on magma genesis and mantle processes in Mars. Abundances of many major and trace elements in the shergottites covary in 2 distinct groups: Group 1 (G1) includes mostly highly incompatible elements (e.g., La, Th), and Group 2 (G2) includes mostly moderately incompatible elements (e.g., Ti, Lu, Al, Hf). Covariations of G2 elements (not necessarily linear) are consistent with partitioning between basalt magma and orthopyroxene + olivine. This fractionation represents partial melting to form the shergottites and their crystallization; the restite minerals cannot include aluminous phase(s), phosphate, ilmenite, zircon, or sulfides. Overall, abundances of G1 elements are decoupled from those of G2. In graphing abundances of a G1 element against those of a G2 element, G1/G2 abundance ratios do not appear to be random but are restricted to 4 values. Shergottites with a given G1/G2 value need not have the same crystallization age and need not fall on a single fractionation trajectory involving compatible elements (e.g., Ti versus Fe*). These observations imply that the G1/G2 families were established before basalt formation and suggest metasomatic enrichment of their source region (major carrier of G2 elements) by a component rich in G1 elements.Group 1 elements were efficiently separated from G2 elements very early in Mars' history. Such efficient fractionation is not consistent with simple petrogenesis; it requires multiple fractionations, "complex" petrogenetic processes, or minerals with unusual geochemistry. The behavior of phosphorus in this early fractionation event is inexplicable by normal petrogenetic processes and minerals. Several explanations are possible, including significant compatibility of P in majoritic garnet and the presence of P-bearing iron metal (or a phosphide phase) in the residual solid assemblage (carrier of G2 elements). If the latter, Mars' mantle is more oxidized now than during the ancient fractionation event.

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“…However, several researchers (e.g., McSween and Jarosewich, 1983;Wadhwa et al, 2001;Barrat et al, 2002;Filiberto et al, 2010) have interpreted the olivine megacrysts in some olivine -phyric shergottites as exotic xenocrysts or cognate xenocrysts mixed into the olivine -free (or olivine -poor) basaltic magma by other processes. Despite the considerable number of studies conducted regarding the igneous origin of basaltic shergottites, the primitive (parent) magma composition of the Martian mantle remains controversial (e.g., Goodrich, 2002;Greshake et al, 2004;Shearer et al, 2008;Usui et al, 2008;Sarbadhikari et al, 2009;Peslier et al, 2010;Filiberto and Dasgupta, 2011).…”

Section: Introductionmentioning

confidence: 99%

Melting of the Martian mantle from 1.0 to 4.5 GPa

Matsukage

Nagayo

Whitaker

et al. 2013

Journal of Mineralogical and Petrological Sciences

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To investigate the chemical composition of possible primitive melts of the Martian mantle, we performed melting experiments of a model Martian mantle derived by Dreibus and Wänke (DWM) at pressures from 1.0 to 4.5 GPa. The chemical compositions of partial melts are systematically related to pressure. The partial melts at pressure of 1.0 GPa in spinel stability field show high Al 2 O 3 and low FeO contents. The partial melts at higher pressure in garnet stability field are, however, characterized by a relatively high FeO content, low Al 2 O 3 content and high CaO/Al 2 O 3 ratio. In garnet stability field, clinopyroxene (= Ca -rich phase) contribute significantly to melt formation near the solidus temperature, although garnet (= Al -rich phase) is stable at temperature above solidus. Therefore Al -poor and Ca -rich partial melt are formed at higher pressure. Comparing the shergottite chemistry with the chemical trends of the partial melts obtained by the experiments, we suggest that one of basaltic shergottite with a high Al 2 O 3 and low CaO/Al 2 O 3 ratio, QUE94201, resembles the composition of the DWM partial melts in major -element chemistry in a low degree (<20%) partial melt of DWM at pressure of 1.0 GPa and temperature of 1360 °C. We conclude that the olivine -poor (or olivine -free) basaltic magma with low CaO/Al 2 O 3 ratio and high Al 2 O 3 could be primitive melts derived from the upper mantle of Mars if the actual Martian mantle is similar in composition to DWM.

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Petrology and chemistry of the Picritic Shergottite North West Africa 1068 (NWA 1068)

Cited by 118 publications

References 47 publications

Matching Martian crustal magnetization and magnetic properties of Martian meteorites

Matching Martian crustal magnetization and magnetic properties of Martian meteorites

Chemical compositions of martian basalts (shergottites): Some inferences on b; formation, mantle metasomatism, and differentiation in Mars

Melting of the Martian mantle from 1.0 to 4.5 GPa

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