The mystery of how Mars meteorites reach Earth may finally be solved

[Admin]

The mystery of how meteorites from Mars can reach Earth may have been solved, as scientists discover rocks can be hhttps://www.space.com/mars-meteorites-on-earth-mysteryed far from the Martian surface by giant impacts.

The mystery of how Mars meteorites reach Earth may finally be solved : Read more

 

[rod]

My observations. Mars escape velocity is a bit more than 5 km/s so blasting off pieces into space is plausible from large impacts. Dating the time and place of these large impacts looks difficult. Consider the Martian meteorite, NorthWest Africa 7533.

Ref - Regolith breccia Northwest Africa 7533: Mineralogy and petrology with implications for early Mars, https://ui.adsabs.harvard.edu/abs/2017M&PS...52...89H/abstract, January 2017. The abstract shows several different radiometric ages that must be reconciled, 4.43 Gyr to 1.35-1.4 Gyr for some ages. The cosmic ray exposure age is about 5 Myr. “The Martian origin of the pyrite is demonstrated by its fracturing caused by shock (Lorand et al. 2015), possibly during the launch event. Wittmann et al. (2015) using Fe and Th abundances, and the ~5 Ma exposure age of Cartwright et al. (2014), suggest one possible launch site for the breccias, the young rayed crater Gratteri. This crater has also been suggested as the source of ALH 84001 (Tornabene et al. 2006).”, ref - Regolith breccia Northwest Africa 7533: Mineralogy and petrology with implications for early Mars, https://onlinelibrary.wiley.com/doi/10.1111/maps.12740, 25-October-2016. “Abstract Northwest Africa 7533, a polymict Martian breccia, consists of fine-grained clast-laden melt particles and microcrystalline matrix. While both melt and matrix contain medium-grained noritic-monzonitic material and crystal clasts, the matrix also contains lithic clasts with zoned pigeonite and augite plus two feldspars, microbasaltic clasts, vitrophyric and microcrystalline spherules, and shards…”

The cosmic ray exposure ages for the Martian meteorites should be shown along with various radiometric ages obtained. Likely will show large impacts ejecting pieces of Mars in the recent past, so catastrophism on Mars still operating perhaps.

 

[billslugg]

From the abstract:
50Mya - the meteoroid ejected into space from Mars
1.4Gya - it was a rock on Mars, pertially melted
4.6 Gya - completely melted

 

[rod]

From the abstract:
50Mya - the meteoroid ejected into space from Mars
1.4Gya - it was a rock on Mars, pertially melted
4.6 Gya - completely melted

The space.com article cites a more recent report, https://www.science.org/doi/10.1126/sciadv.adf2906, 'Shock-recovered maskelynite indicates low-pressure ejection of shergottites from Mars', 03-May-2023. I did not find specific radiometric ages or exposure ages provided or any specific ejection times from Mars. The paper does briefly mention this, "In turn, a decrease in the estimate of shock pressure in the shergottites increases the rarity of ejection of unmelted rocks and increases the probability that the known shergottites were ejected by fewer impact events, given their narrow range of cosmic ray exposure ages (51)." The ref - 51R. [Wieler, L. Huber, H. Busemann, S. Seiler, I. Leya, C. Maden, J. Masarik, M. M. M. Meier, K. Nagao, R. Trappitsch, A. J. Irving, Noble gases in 18 martian meteorites and angrite Northwest Africa 7812—Exposure ages, trapped gases, and a re-evaluation of the evidence for solar cosmic ray-produced neon in shergottites and other achondrites. Meteorit. Planet. Sci. 51, 407–428 (2016).]

The NorthWest Africa 7533 shows an exposure age of 5 Myr, not a 50 Myr ejected into space from Mars, ref - https://onlinelibrary.wiley.com/doi/10.1111/maps.12740

It seems very difficult to sort all of the different radiometric ages found (reported values) and the exposure ages (reported) for all the Martian meteorites. I note this from the paper about NorthWest Africa 7533. "(2) The lithification age is ~1.4 Ga. Yin et al. (2014) argued that some of the zircon analyses at the lower intercept were actually concordant grains that crystallized from melts at ~1.4 Ga. This led them to interpret the lithification age of the breccia as ~1.4 Ga. This model of the assembly time cannot explain the absence of zircons between 4.35–1.4 Ga, but is more permissive to sampling a very wide range of Martian history (~3 Ga), even if not recorded by zircon-forming events. Resolving these two models is essential to fully reading the record of ancient Mars from this breccia."

I find the various dating methods and reconciliation explanations - intriguing.

 

[rod]

FYI, the space.com article using ref 51 I found at the NASA ADS Abstract site.

Noble gases in 18 Martian meteorites and angrite Northwest Africa 7812—Exposure ages, trapped gases, and a re-evaluation of the evidence for solar cosmic ray-produced neon in shergottites and other achondrites, https://ui.adsabs.harvard.edu/abs/2016M&PS...51..407W/abstract, Feb-2016.

"We present noble gas data for 16 shergottites, 2 nakhlites (NWA 5790, NWA 10153), and 1 angrite (NWA 7812). Noble gas exposure ages of the shergottites fall in the 1-6 Ma range found in previous studies. Three depleted olivine-phyric shergottites (Tissint, NWA 6162, NWA 7635) have exposure ages of ~1 Ma, in agreement with published data for similar specimens. The exposure age of NWA 10153 (~12.2 Ma) falls in the range of 9-13 Ma reported for other nakhlites. Our preferred age of ~7.3 Ma for NWA 5790 is lower than this range, and it is possible that NWA 5790 represents a distinct ejection event."

Exposure ages shown are very young.

 

[Atilla De Bum]

That large canyon on Mars appears to be gouged out from a glancing blow from a large asteroid. An impact of that size could have easily stripped the atmosphere from the planet and thrown untold tons of surface material into space.