Thermal and irradiation history of lunar meteorite Dhofar 280

Korochantseva, E. V.; Buikin, A. I.; Hopp, J.; Lorenz, C. A.; Korochantsev, A. V.; Ott, U.; Trieloff, M.

doi:10.1111/maps.12732

Cited by 9 publications

(13 citation statements)

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“…Two whole rock (WR) samples (Dhofar 1436-a and Dhofar 1436-b) weighing 25.8 and 31.1 mg were used for 40 Ar- 39 Ar dating. Our previous study of the meteorite Dhofar 280 (Korochantseva et al 2016) has demonstrated that significant chronological and geochemical information could be obtained by analyzing a WR chip of the Dhofar 280 lunar impact melt breccia. The sample Dhofar 1436-b contained a higher proportion of clastic material than Dhofar 1436-a.…”

Section: Sample Descriptionmentioning

confidence: 99%

“…Ozima et al (2004) noted quantitative problems with the origin of the orphan argon according to the "antiquity" scenario. There are data (Fernandes et al 2000(Fernandes et al , 2003Cohen et al 2005b;Korochantseva et al 2016) inconsistent with the empirical antiquity model (Eugster et al 2001), raising the issue about a simple relation between age and the trapped 40 Ar/ 36 Ar ratio in lunar samples.…”

Section: Introductionmentioning

confidence: 99%

“…In lunar samples, indigenous trapped Ar components generally consist of solar wind, fractionated solar wind, planetary (P1 or Q), and orphan Ar (see below). Lunar meteorites found in terrestrial deserts are frequently contaminated by atmospheric argon, which is released during the gas extractions mostly at low and intermediate temperature steps (<1000°C; e.g., Korochantseva et al 2016). Such atmospheric Ar can be well separated from the indigenous high-temperature lunar trapped components (Fernandes et al 2000;Korochantseva et al 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Lunar meteorites found in terrestrial deserts are frequently contaminated by atmospheric argon, which is released during the gas extractions mostly at low and intermediate temperature steps (<1000°C; e.g., Korochantseva et al 2016). Such atmospheric Ar can be well separated from the indigenous high-temperature lunar trapped components (Fernandes et al 2000;Korochantseva et al 2016). In addition, the isochron analysis, used in the high-resolution 40 Ar- 39 Ar dating for deconvolution of radiogenic and trapped Ar components, is a suitable method for precise evaluation of the extraterrestrial trapped argon composition (Korochantseva et al 2007).…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the isochron analysis, used in the high-resolution 40 Ar- 39 Ar dating for deconvolution of radiogenic and trapped Ar components, is a suitable method for precise evaluation of the extraterrestrial trapped argon composition (Korochantseva et al 2007). Another advantage of this high-resolution technique is that a complicated irradiation history-lunar meteorites typically experienced irradiation in different geometries and for different durations-can be distinguished in favorable cases by using the 37 Ar- 38 Ar cos cosmic-ray exposure (CRE) age spectrum (Korochantseva et al 2016).…”

Section: Introductionmentioning

confidence: 99%

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The lunar Dhofar 1436 meteorite: ⁴⁰Ar‐³⁹Ar chronology and volatiles, revealed by stepwise combustion and crushing methods

Korochantseva

Buikin

Hopp

et al. 2021

Meteorit & Planetary Scien

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The lunar meteorite Dhofar 1436 is dominated by solar wind type noble gases. Solar argon is equilibrated with "parentless" 40 Ar commonly known as lunar orphan argon. Ar-Ar isochron analyses determined the lunar trapped 40 Ar/ 36 Ar ratio to 2.51 AE 0.04, yielding a corrected plateau age of 4.1 AE 0.1 Ga, consistent with the lunar Late Heavy Bombardment period. Lunar trapped and radiogenic argon components are all released at high temperatures (1200-1400°C). Surprisingly, solar noble gases and lunar trapped argon can largely be released by crushing. Initial crushing steps mainly release elementally fractionated solar wind gases, while in advanced crushing steps, cosmogenic components dominate. Cosmogenic noble gases indicate irradiation at the lunar surface; they are less fractionated than solar wind species. We favor a scenario in which both solar and a large fraction of cosmogenic gases were acquired before the 4.1 Ga event, which caused shock metamorphism and formation of the regolith breccia. Sintering and agglutination along grain boundaries resulted in mobilization of solar wind, reimplanted, radiogenic, and cosmogenic noble gases, and resulted in their partial homogenization, fractionation, and retrapping in voids and/or defects accessible by crushing. An alternative scenario would be complete reset of the K-Ar system 4.1 Ga ago accompanied by loss of all previously accumulated solar and cosmogenic noble gases. Later, the precursor of Dhofar 1436 became lunar regolith and accumulated solar and cosmogenic noble gases and reimplanted 40 Ar before its final formation of the polymict impact breccia. The C abundance of the stepcombusted Dhofar 1436 is 555.3 ppm, with δ 13 C of −28‰ to +11‰. Nitrogen contents released by crushing and combustion are 3.2 ppm and 20.8 ppm, respectively. The lightest nitrogen composition (δ 15 N = −79‰) is likely due to release from voids of shock metamorphic phases and is rather a result of the mobilization of nitrogen components that accumulated prior to the 4.1 Ga event.

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Section: Sample Descriptionmentioning

confidence: 99%