NWA 7034

[Chondrit 83]

Genial finde ich auch das zweite Marsgesicht auf Bild 5 

Nein Spaß bei Seite, das ist ein absolut geniales Stück 
 

Grüßle

Marco

[karmaka]

Nun bekommt auch der gepaarte NWA 7533 seine Medienaufmerksamkeit:

Origin and age of the earliest Martian crust from meteorite NWA 7533

M. Humayun, A. Nemchin, B. Zanda, et al

    Nature (2013) doi:10.1038/nature12764
    Published online 20 November 2013

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The ancient cratered terrain of the southern highlands of Mars is thought to hold clues to the planet’s early differentiation1, 2, but until now no meteoritic regolith breccias have been recovered from Mars. Here we show that the meteorite Northwest Africa (NWA) 7533 (paired with meteorite NWA 70343) is a polymict breccia consisting of a fine-grained interclast matrix containing clasts of igneous-textured rocks and fine-grained clast-laden impact melt rocks. High abundances of meteoritic siderophiles (for example nickel and iridium) found throughout the rock reach a level in the fine-grained portions equivalent to 5 per cent CI chondritic input, which is comparable to the highest levels found in lunar breccias. Furthermore, analyses of three leucocratic monzonite clasts show a correlation between nickel, iridium and magnesium consistent with differentiation from impact melts. Compositionally, all the fine-grained material is alkalic basalt, chemically identical (except for sulphur, chlorine and zinc) to soils from Gusev crater. Thus, we propose that NWA 7533 is a Martian regolith breccia. It contains zircons for which we measured an age of 4,428 ± 25 million years, which were later disturbed 1,712 ± 85 million years ago. This evidence for early crustal differentiation implies that the Martian crust, and its volatile inventory4, formed in about the first 100 million years of Martian history, coeval with earliest crust formation on the Moon5 and the Earth6. In addition, incompatible element abundances in clast-laden impact melt rocks and interclast matrix provide a geochemical estimate of the average thickness of the Martian crust (50 kilometres) comparable to that estimated geophysically2, 7.

FOTO

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Im Oktober gab der Geochemiker Prof. Munir Humayun des MagLab (National High Magnetic Field Laboratory)
im Backwoods Bistro in Tallahassee, Florida bereits einen öffentlichen einstündigen Vortrag über Mars- und Mondmeteorite, einschließlich NWA 7533:

VIDEO-LINK

Hier ist noch ein Artikel und ein kurzes Interview von der Website der Florida State University (21.11.13):

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NWA 8171 ist nun auch official

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Glückwunsch an alle Besitzer!

[netmet]

Zitat von Carl Agee heute in Facebook bezüglich 7034 :
"Actually this martian meteorite is much more fertile ground to look for little green men than the more famous ALH 84001. It is a breccia, has a bulk composition that is basaltic, but it is polymict with at least 6 different igneous lithologies, there are rounded objects that could be sedimentary, there are impact melt clasts, there appears to be a non-martian meteoritic component (like that found in the lunar regolith). So far there are three age dates for NWA 7034 perhaps representing major events during its residence on Mars at 1.4, 2.1, 4.4 billion years ago. NWA 7034 has 6000 ppm water, more than ten times the water in other martian meteorites. I could go on and on, but I recommend the LPSC instead, should be a great meeting. The meteoritic component idea is work by Munir Humayun and Randy Korotev. They see elevated highly siderophile elements including platinum group especially iridium. This also seen in the lunar breccias and is thought to be from impactor(s) perhaps taking place in the ancient martian highlands early in Mars history. To my knowledge no other martian meteorites have this."

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Zur 45th Lunar and Planetary Science Conference gibt es Neues und Spannendes zu NWA 7034 und seinen pairings:

Hier ist eine Übersicht mit den Links zum Schmökern:

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Modern atmospheric signatures in 4.4 Ga Martian meteorite NWA 7034.

J.A. Cartwright, U. Ott, S. Herrmann, C.B. Agee

LINK

Earth and Planetary Science Letters 400:77.

Highlights

•First noble gas analysis of Martian meteorite NWA 7034.
•Data reveal a distinct trapped component, similar to modern Martian atmosphere.
•This finding confirms Martian origin for this sample.
•K–Ar & U–Th/He ages are 1600 and 170 Ma, similar to U–Pb event and shergottite age.
•CRE ages suggest ejection at ∼5 Ma, distinct from the other Martian meteorites.

The NWA 7034 Martian basaltic breccia, dated at ∼4.4 Ga∼4.4 Ga, represents an entirely new type of Martian meteorite. However, due to the unique make-up of NWA 7034 compared to other Martian meteorite types (including its anomalous oxygen isotope ratios), noble gas analyses – a key tool for Martian meteorite identification – are important to confirm its Martian origin. Here, we report the first noble gas results for NWA 7034, which show the presence of a trapped component that resembles the current Martian atmosphere. This trapped component is also similar in composition to trapped gases found in the much younger shergottites (∼150–600 Ma∼150–600 Ma). Our formation ages for the sample suggest events at ∼1.6 Ga (K–Ar), and ∼170 Ma (U–Th/He), which are considerably younger than those observed by Rb–Sr (2.1 Ga), and Sm–Nd (4.4 Ga; zircons ∼4.4 Ga). However, our K–Ar age is similar to a disturbance in the U–Pb zircon data at ∼1.7 Ga, which could hint that both chronometers have been subjected to disturbance by a common process or event. The U–Th/He age of ∼170 Ma could relate to complete loss of radiogenic 4He at this time, and is a similar age to the crystallisation age of most shergottites. While this may be coincidental, it could indicate that a single event is responsible for both shergottite formation and NWA 7034 thermal metamorphism. As for cosmic ray exposure ages, our favoured age is ∼5 Ma, which is outside the ranges for other Martian meteorite groups, and may suggest a distinct ejection event. NWA 7034 shows evidence for neutron capture on Br, which has caused elevations in Kr isotopes 80Kr and 82Kr. These elevated abundances indicate significant shielding, and could relate to either a large meteoroid size, and/or shielding in relation to a regolithic origin. We have also applied similar neutron capture corrections to Ar and Xe data, which further refine the likelihood of a modern atmospheric component, though such corrections remain speculative. Cosmogenic production rates and noble gas data are consistent with a meteoroid radius of >50 cm. Fission contributions are clear in the Xe data, with evidence to suggest that NWA 7034 contains both 238U and 244Pu derived fission Xe components. If the gas in NWA 7034 was trapped at its ancient igneous formation, this would suggest little evolution of the Martian atmosphere between ∼4.4 Ga and present day. However, as NWA 7034 is a regolith breccia with multiple lithologies and a strong compositional similarity to Gusev soils, the timing and incorporation of trapped atmospheric gases is unclear. With hints of resetting events at ∼1.5–2.1 Ga∼1.5–2.1 Ga, the atmospheric component may have been incorporated during breccia formation – possibly in the Amazonian, though it could also have been incorporated on ejection from the surface.

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Petrogenesis of a vitrophyre in the martian meteorite breccia NWA 7034

Udry A, Lunning NG, McSween JR. HY and Bodnar RJ

Geochimica et Cosmochimica Acta
[doi:10.1016/j.gca.2014.06.026]
Available online 9 July 2014

LINK

Northwest Africa (NWA) 7034 and its paired meteorites NWA 7533 and NWA 7475 are the first recognized martian polymict breccia samples. An unusual, large, subrounded clast in NWA 7034 shows a vitrophyric texture, consisting of skeletal pyroxene and olivine with mesostasis. This lithology has not been observed in the paired meteorites. It crystallized under disequilibrium conditions as indicated by its olivine and pyroxeneKDFe/Mg partitioning values, as well as reversed order of crystallization and mineral compositions relative to those predicted by MELTS. We report the highest bulk Ni value (1020 ppm) measured in any known martian meteorite or martian igneous rock, suggesting an impact melt origin for the vitrophyre. Addition of 5.3-7.7% chondritic material to the target rock would account for the Ni enrichment. The bulk major and trace element abundances of the vitrophyre indicate that the protolith was not the host breccia nor any other martian meteorites. However, the clast is compositionally similar to Humphrey rock in Gusev crater analyzed by the Spirit rover and to a texturally distinct group of clasts in the paired meteorite NWA 7533. Thus, we propose that the target rock was an igneous lithology similar to Gusev basalts, which was subsequently contaminated by a chondritic impactor.

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Martian meteorites and Martian magnetic anomalies: a new perspective from NWA 7034

J. Gattacceca, P. Rochette, R. B. Scorzelli, P. Munayco, C. Agee, Y. Quesnel, C. Cournède and J. Geissman

Geophysical Research Letters, DOI: 10.1002/2014GL060464
Accepted manuscript online: 14 JUL 2014 07:55PM EST

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We present the magnetic properties of the Noachian Martian breccia NWA 7034. Among the 25 unpaired Martian meteorites studied to date, NWA 7034 has a unique magnetic mineralogy. It contains about 15 wt. % of iron oxides as magnetite that has experienced cation substitution and partial alteration to maghemite, with about a quarter of the oxides being pure maghemite. It also contains oxyhydroxides in the form of superparamagnetic goethite. The presence of maghemite and goethite makes NWA 7034 the most oxidized Martian meteorite. The overall magnetic assemblage is partly linked to near-surface hydrothermal alteration. The high concentration of magnetic phases with high laboratory unblocking temperatures makes NWA 7034 a plausible analogue source lithology for the strong magnetization of the Martian Noachian crust. Near surface hydrothermal alteration can enhance the remanence of Martian rocks and account for local, high magnetic anomalies of shallow source.

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40Ar/39Ar Ages of Martian Meteorite NWA 7533

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New Data for NWA 7906, 7907 and 8171, Pairings of Mars Breccia NWA 7034

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What Mars is Made of: Reconciling Orbital Datasets with Clues from the
Spectrum of Northwest Africa 7034

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A complex thermal history of the Southern Highlands
preserved in Martian meteorite NWA7533 and its pairs.

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Ein längerer Artikel, in dem das dopplete M Word leider wieder sehr in den Vordergrund gerückt wurde.

Feature: A castaway from ancient Mars by Eric Hand
Science, 25 November 2014

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The Black Beauty meteorite

Science Podcast: 28 November 2014

Eric Hand discusses the winding history of the Black Beauty meteorite--a 4.4 billion-year-old piece of Mars.

AUDIO-LINK

(ab 9:20 Min. Laufzeit)

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Neues zu NWA 7533

Pb-isotopic evidence for an early, enriched crust on Mars      open access

J.J. Bellucci, A.A. Nemchin, M.J. Whitehouse, M. Humayun, R. Hewins, B. Zanda

Earth and Planetary Science Letters
Volume 410, 15 January 2015, Pages 34–41
available online 2 December 2014

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NWA 7034 im CT Scan

VIDEO-LINK

This video was made from CT scans of a slice (45 mm x 55 mm x 4 mm) of the NWA 7034 (AKA “Black Beauty”) Martian meteorite from the ASU Center for Meteorite Studies collection. This meteorite is a polymict breccia containing a diverse assemblage of igneous and “sedimentary” materials. It was most likely produced by impact, but also involved volcanic and low-temperature alteration processes. The bulk chemical composition of this meteorite closely matches that of the Martian crust as measured by NASA’s Mars Exploration Rovers and Mars Odyssey Orbiter. It also contains the most amount of water (approximately ~0.6 wt%) of any of the known Martian meteorites. The CT imaging of this meteorite slice was performed at the American Museum of Natural History, New York.

Quelle: ASU Center for Meteorite Studies

[aknoefel]

Ein kleiner Artikel zum NWA 7034 in den Yahoo!-Nachrichten

Schwarz statt rot: So sieht der Mars aus
Einzigartiger Meteorit gibt Aufschluss über Planetenoberfläche