The meteorite flux of the past 2 m.y. recorded in the Atacama Desert

We describe the geological, geomorphological, and paleoclimatic setting of the Sahara of North Africa in particular, focused on the main meteorite dense collection areas (DCA; Morocco, Algeria, Tunisia, and Libya). We report on the outcome of several meteorite recovery field expeditions in Morocco and Tunisia since 2008, by car and by foot, that applied systematic search methods. The number of meteorites collected is 41 ordinary chondrites and one brachinite. The statistics of unpaired ordinary chondrites indicates that H chondrites are more abundant (21) than L chondrites (12), while LL chondrites are rare (2). Our meteorite density estimates for Tunisia and Morocco are in the order of magnitude of 1 met km−2. An estimate of the total maximum number of meteorites that could be recovered from the Sahara is 780,000 meteorites. We selected 23 meteorites from Aridal, Bou Kra, Bir Zar, and Tieret DCAs for 14C dating. The results show a wide range of terrestrial ages from 0.4 to more than 40 kyr with a majority of meteorites showing ages between 0.4 and 20 kyr. The weathering degree of these meteorites is ranges from minor (W1) to strong (W4). The highest weathering grades result from repeated oscillations between high and low humidity in the Sahara. However, there appears to be no correlation between weathering grade and terrestrial age of meteorites.

Section: Dca Name Countrysupporting

confidence: 85%

“…() with 100 meteorites per year per 1 million km 2 (>10 g) based on meteor detections and mathematics calculation model, as well as the flux estimated by Drouard et al. () with 222 meteorites larger than 10 g per km 2 perMyr.…”

Section: Discussionmentioning

confidence: 96%

Characteristics of the Sahara as a meteorite recovery surface

Aboulahris

Aoudjehane

Rochette

et al. 2019

“…Caleta el Cobre 022 was found casually by tourists traveling in the Atacama Desert, Chile, in November 2016, lying at the surface in the CeC dense collection area, which is part of the densest meteorite collection area in hot deserts (Hutzler et al 2016;Drouard et al 2019). It is a single stone, almost fully crusted.…”

Section: General Description and Physical Propertiesmentioning

confidence: 99%

Caleta el Cobre 022 Martian meteorite: Increasing nakhlite diversity

Ruggiu

Gattacceca

Devouard

et al. 2020

Self Cite

Caleta el Cobre (CeC) 022 is a Martian meteorite of the nakhlite group, showing an unbrecciated cumulate texture, composed mainly of clinopyroxene and olivine. Augite shows irregular core zoning, euhedral rims, and thin overgrowths enriched in Fe relative to the core. Low‐Ca pyroxene is found adjacent to olivine. Phenocrysts of Fe‐Ti oxides are titanomagnetite with exsolutions of ilmenite/ulvöspinel. Intercumulus material consists of both coarse plagioclase and fine‐grained mesostasis, comprising K‐feldspars, pyroxene, apatite, ilmenite, Fe‐Ti oxides, and silica. CeC 022 shows a high proportion of Martian aqueous alteration products (iddingsite) in olivine (45.1 vol% of olivine) and mesostasis. This meteorite is the youngest nakhlite with a distinct Sm/Nd crystallization age of 1.215 ± 0.067 Ga. Its ejection age of 11.8 ± 1.8 Ma is similar to other nakhlites. CeC 022 reveals contrasted cooling rates with similarities with faster cooled nakhlites, such as Northwest Africa (NWA) 817, NWA 5790, or Miller Range 03346 nakhlites: augite irregular cores, Fe‐rich overgrowths, fine‐grained K‐feldspars, quenched oxides, and high rare earth element content. CeC 022 also shares similarities with slower cooled nakhlites, including Nakhla and NWA 10153: pyroxene modal abundance, pyroxenes crystal size distribution, average pyroxene size, phenocryst mineral compositions, unzoned olivine, and abundant coarse plagioclase. Moreover, CeC 022 is the most magnetic nakhlite and represents an analog source lithology for the strong magnetization of the Martian crust. With its particular features, CeC 022 must originate from a previously unsampled sill or flow in the same volcanic system as the other nakhlites, increasing Martian sample diversity and our knowledge of nakhlites.

“…However, shifting the discussion to the meteorites, other interesting data can be found. In fact, Zolensky et al (2006) provided a total mass flux to Earth (in the meteorite weight range 10 g–10 6 g) of 5.38·10 4 kg yr –1 whereas Drouard et al (2019) found a flux of 222 meteorites (>10 g) per km 2 per m.y. According to these data, over an area of 59,000 km 2 , that is the area covered by Obsequens’s events (Fig.…”

Section: Discussionmentioning

confidence: 99%

Julius Obsequens’s book, Liber Prodigiorum: A Roman era record of meteorite falls, fireballs, and other celestial phenomena

Franza

Pratesi

2020

Julius Obsequens was the pseudonym of a Roman historian presumably living in the 4th century ad, whose life is shrouded in mystery. All that is known about Obsequens’s biography is that he was the author of a book entitled Liber Prodigiorum (Book of Prodigies), a collection of prodigies deduced from Livy’s Ab Urbe Condita Libri (Books from the Founding of the City). The Liber Prodigiorum covered the period from 190 to 11 bc and gathered a chronological list of portents of various kinds (e.g., births of monstrous animals or men, statues that shed blood, voices from beyond the grave, epidemics, earthquakes, unidentified flying objects). Among these extraordinary reports, chronicles of celestial phenomena were also included. The interdisciplinary approach adopted in this research has clarified the nature of the events described in the text and has enabled the identification of new Italian meteorite falls that are not included in the Meteoritical Bulletin Database.