# Dense collection areas and terrestrial alteration of meteorites in the Atacama Desert

Gabriel Pinto, Adrien Tavernier, Jérôme Gattacceca, Alexandre Corgne, Millarca Valenzuela, Béatrice Luais, Laura Flores, Felipe Olivares, Yves Marrocchi

► To cite this version:

Gabriel Pinto, Adrien Tavernier, Jérôme Gattacceca, Alexandre Corgne, Millarca Valenzuela, et al. Dense collection areas and terrestrial alteration of meteorites in the Atacama Desert. Meteoritics and Planetary Science, 2024, 59 (2), pp.351-367. 10.1111/maps.14125. hal-04372993

HAL Id: hal-04372993

https://hal.science/hal-04372993v1

Submitted on 14 Nov 2024

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
# Dense collection areas and terrestrial alteration of meteorites in the Atacama Desert

Gabriel A. PINTO<sup>1,2,3*</sup>, Adrien TAVERNIER<sup>4</sup>, Jérôme GATTACCECA<sup>5</sup>,
Alexandre CORGNE<sup>3</sup>, Millarca VALENZUELA<sup>6,7</sup>, Béatrice LUAIS<sup>1</sup>, Laura FLORES<sup>8</sup>,
Felipe OLIVARES<sup>2</sup>, and Yves MARROCCHI<sup>1</sup>

(Received 11 August 2023; revision accepted 19 December 2023)

**Abstract**—In the last 15 years, more than 2700 meteorites have been recovered and officially classified from the Atacama Desert. Although the number of meteorites collected in the Atacama has risen, the physical and climatic properties of the dense collection areas (DCAs) have not been fully characterized. In this article, we compiled the published data of all classified meteorites found in the Atacama Desert to (i) describe the distribution by meteorite groups, (ii) compare the weathering degree of chondrites among different Atacama DCAs and other hot and cold deserts, and (iii) determine the preservation conditions of chondrites in the main Atacama DCAs in relation with the local climatic conditions. The 35 DCAs so far identified in the Atacama Desert are located in three main morphotectonic units: The Coastal Range (CR), Central Depression (CD), and Pre-Andean Range/Basement. A comparison with reported weathering data from other cold and hot deserts indicates that the mean terrestrial weathering of Atacama chondrites (W1–2), displays less alteration than other hot deserts (W2–3) and resembles the weathering distribution of the Antarctic meteorites (W1–2). The highest abundance of Atacama chondrites with low weathering (≤W2) is localized in the CD (78.8%, N=1435), which is protected from the coastal fog influence and seasonal rainfalls and displays the oldest surfaces in the Atacama Desert. The morphogenetic classification based on present-day temperatures and precipitations of the main Atacama DCAs reveals similar regional/subregional climatic conditions in the most productive areas and a truly productive surface for meteorite recovery between 5% and 58% of the quadrangles formally defined for each Atacama DCA. Our morphogenetic classification lacks consideration of some meteorological parameters such as the coastal fog, so it cannot fully explain the differences in weathering patterns among CR chondrites. Future studies of chondrite preservation in the Atacama DCAs should consider other meteorological variables such as relative humidity, specific humidity, or dew point, in combination with exposure ages of meteorites and its surfaces.

<footnote n="1"><sup>1</sup>CNRS, CRPG, UMR 7358, Université de Lorraine, Vandœuvre-lès-Nancy, France</footnote>

<footnote n="2"><sup>2</sup>Instituto de Astronomía y Ciencias Planetarias, Universidad de Atacama, Copiapó, Chile</footnote>

<footnote n="3"><sup>3</sup>Instituto de Ciencias de la Tierra, Universidad Austral de Chile, Valdivia, Chile</footnote>

<footnote n="4"><sup>4</sup>IDICTEC, LICA, Universidad de Atacama, Copiapó, Chile</footnote>

<footnote n="5"><sup>5</sup>CNRS, IRD, INRAE, CEREGE, Aix Marseille Université, Aix-en-Provence, France</footnote>

<footnote n="6"><sup>6</sup>Millennium Institute of Astrophysics, Santiago, Chile</footnote>

<footnote n="7"><sup>7</sup>Departamento de Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile</footnote>

<footnote n="8"><sup>8</sup>Leibniz Centre for Agricultural Landscape Research, Müncheberg, Germany</footnote>

<footnote>*Correspondence</footnote>

<footnote>Gabriel A. Pinto, CNRS, CRPG, UMR 7358, Université de Lorraine, Vandœuvre-lès-Nancy 54501, France.</footnote>

<footnote>Email: gabriel.pinto@univ-lorrain.fr</footnote>
INTRODUCTION

Meteorites are divided into falls or finds depending on whether they were observed by humans or monitoring devices before landing or not. Meteorite finds accumulate preferentially in desertic areas, where the chemical weathering is slow enough to preserve samples over hundreds to millions of years (Bland et al., 1998, 2006; Nishiizumi et al., 1989). The areas where meteorites are preserved in large numbers are called dense collection areas (hereafter DCAs) and their size depends basically on the local and regional geography.

About 60% of all meteorite finds come from Antarctica (Meteoritical Bulletin Database, as of June 2023, https://www.lpi.usra.edu/meteor/), while 35% come from hot desert DCAs including North West Africa (NWA) meteorites. The recovery of hot desert meteorites has significant advantages compared to that of Antarctica meteorites, such as easier accessibility, which implies lower expedition costs and passive accumulation of meteorites (versus concentration processes in Antarctica). This allows the preservation of the initial fall location that can help studying strewn fields (e.g., Gnos et al., 2009; Kring et al., 2001; Pedersen et al., 1992; Zeng et al., 2018) and the meteorite flux (Bland, 2001; Drouard et al., 2019). Nevertheless, several studies have provided evidence for the significant terrestrial alteration of hot desert meteorites in comparison with Antarctic meteorites (Lee & Bland, 2004; Maeda et al., 2021; Pourkhorsandi et al., 2022). This distinction has cast doubt on the consideration that hot desert meteorites are suitable samples for investigating pre-terrestrial processes (Pourkhorsandi et al., 2017).

Numerous factors can influence the terrestrial weathering of meteorites: the time spent in the terrestrial environment (called terrestrial age); the composition of the soil of the recovery site; the long-term meteorological conditions of the area; and the chondrite group, size, shape, and porosity (e.g., Al-Kathiri et al., 2005; Ouknine et al., 2019; Pourkhorsandi et al., 2022; Stephant et al., 2018; Valenzuela, 2011). Although the weathering products of chondrites are distinct in hot and cold deserts, comparing the degree of weathering of a large set of chondrites is challenging due to different classification systems. The weathering degree classification of Antarctic chondrites and achondrites is based on a visual inspection of the specimens, for which minor, moderate, and severe rusting are referred as A, B, or C, respectively (Bland et al., 2006). However, it should be noted that visual alteration does not always align with chemical modifications (Pourkhorsandi et al., 2017). Based on polished sections of ordinary chondrites (OCs), Wlotzka (1993) introduced a weathering scale that ranges from W0 to W6. W0 represents a pristine fall chondrite. The alteration of metals starts in

W1 and that of troilites in W2. In W3, moderate stages of alteration affect both metal and troilite, while in W4, both components are almost entirely replaced by oxy-hydroxides. The alteration of ferromagnesian silicates starts in W5, and in W6, there is a substantial replacement of these silicates by clays and oxides (Bland et al., 2006; Wlotzka, 1993). Out of the approximately 34,233 OCs discovered in Antarctica (as reported in the Meteoritical Bulletin Database, as of June 2023), only ~20% have been classified using the W0-W6 scale (Wlotzka, 1993). The remaining ~80% have (i) no precise classification (e.g., W0/4), (ii) different weathering scales, or (iii) no information. By contrast, it is more common to use the W0-W6 weathering scale to classify chondrites from hot deserts. For instance, Atacama, the Sahara, and Oman deserts display 96%, 80%, and 83% of chondrites classified according to this weathering scale, respectively.

Three decades ago, hot desert meteorites derived mainly from Australia (Bevan & Binns, 1989), Northern Africa (Aboulahris et al., 2019; Bischoff & Geiger, 1995; Ouazaa et al., 2009; Schlüter et al., 2002), and the Southwestern United States (Hutson et al., 2013; Kring et al., 2001; Rubin et al., 2000; Zolensky et al., 1990). More recent expeditions in the Arabian Peninsula (Hezel et al., 2011; Hofmann et al., 2018), Northern and Western China (Fan et al., 2022), Lut Desert (Pourkhorsandi et al., 2019), and the Atacama Desert (Gattacceca et al., 2011; Hutzler et al., 2016) have allowed the characterization of an extensive set of new DCAs. These new DCA studies are useful to constrain (i) the flux of extraterrestrial material to Earth over time (Drouard et al., 2019), (ii) the statistics of number and mass of meteorites at continental scale (Acevedo et al., 2014; Ouknine et al., 2019), and (iii) the paleoclimatic conditions of the areas from which meteorites have been recovered (Bland et al., 2006).

The Atacama Desert, located between Southern Peru (15°S) and Northern Chile (30°S), is one of the driest environments in the world (precipitation <10 mm year⁻¹; Goudie et al., 2002; Houston & Hartley, 2003; Pfeiffer et al., 2021). These arid to hyperarid conditions result from the reduced precipitation and the evapotranspiration capabilities of its surfaces (Boy et al., 2022; Dunai et al., 2005; Pfeiffer et al., 2021). In the El Médano DCA, the meteorological conditions and geological stability of Atacama surfaces led to the preservation of about up to 170 meteorites with a mass >10 g km⁻² after pairing (Hutzler et al., 2016), with a mean terrestrial age of 710 ky (Drouard et al., 2019). Twenty years ago, only 64 unpaired meteorites had been reported from the Atacama Desert (Muñoz et al., 2007). Today, 2767 meteorites have been recovered from 35 DCAs (Meteoritical Bulletin Database, as of June 2023). Despite the rise in the number of collected meteorite samples, a detailed physical and
climatic characterization of the Atacama DCAs is currently lacking. To fill this gap, we compiled the published data of all meteorites found in the Atacama Desert and registered in the Meteoritical Bulletin Database to (i) quantify the relative abundance of each meteorite group and describe internal group statistics, (ii) compare the weathering degree of chondrites among different Atacama DCAs and other hot and cold deserts, and (iii) determine the local climatic conditions that influence the chondrite preservation in the main Atacama DCAs.

## STATISTICS OF METEORITE FINDS FROM THE ATACAMA DESERT

Meteorites from the Atacama Desert are mostly found on deflation surfaces (Figure 1). The meteorite's initial properties, the nature of the soil, and the climatic conditions control the subsequent alteration of these meteorites. Their relative abundances by type and classes are distinct, whether they are computed by meteorite number or meteorite mass. This difference is mostly controlled by the meteoroid nature (e.g., density and initial size), fragmentation, and preservation during atmospheric entry and subsequent weathering (Bland et al., 2006). By number, chondrites make up the largest fraction (96.7 ± 0.6%, uncertainty with a 95% confidence interval) of the Atacama meteorites (N = 2767, Figure 2), slightly higher than the worldwide abundance of chondrites (90.4 ± 0.2%; Meteoritical Bulletin Database, as of June 2023). They are followed by irons (1.7 ± 0.5%, N = 50), stony achondrites (1.0 ± 0.4%, N = 29), and stony irons (0.4 ± 0.2%, N = 11). The abundance of stony achondrites is significantly below worldwide values (7.1 ± 0.2%), while irons and stony irons are similar to worldwide values (1.7 ± 0.1% and 0.7 ± 0.1%, respectively; Figure 2). In the following sections, we detailed the statistics by types of meteorites compared to the world collection.

### Differentiated Meteorites

Fifty iron meteorites have been found in the Atacama Desert. The most common belong to the IIIAB group (30 ± 12.7% of iron meteorites, Figure 2a). Among the 15 reported IIIAB irons, 11 have trace element compositions that are sufficiently different to discard pairing (Wasson & De Bon, 1998). Furthermore, similar abundances are displayed in the worldwide meteorite collection (28.2 ± 2.5%, Figure 2b). The second most abundant iron meteorites in the Atacama are the IAB irons (including ungrouped IAB) with a proportion of 18 ± 10.6%, which is significantly below the worldwide value of 29.7 ± 2.6%. IIAB and IVA represent 16 ± 10.2% and 10 ± 8.3% of the Atacama irons, respectively,

relatively close to their corresponding worldwide values of 12 ± 1.8% and 7.3 ± 1.5%. The stony-iron meteorites in the Atacama Desert are represented by nine mesosiderites and two pallasites. The two largest meteorites found in the Atacama Desert belong to this group: Imilac pallasite (920 kg; Killgore, 1997) and Vaca Muerta mesosiderite (3830 kg; Pedersen et al., 1992).

Twenty-six differentiated achondrites, two primitive achondrites, and one Martian meteorite have been found in the Atacama Desert. Howardites, eucrites, and diogenites (HEDs) are the most abundant group of differentiated achondrites (Krot et al., 2014), representing 54.4 ± 1.4% of this group in the world collection and 55.2 ± 18.1% (N = 16) in the Atacama collection (Meteoritical Bulletin Database, as of June 2023). The 16 Atacama HEDs correspond to eight eucrites, four diogenites, and four howardites (including the fresh Cariquima meteorite shown in Figure 1c), which reflect roughly the proportions obtained worldwide for this group. The only Martian meteorite found in the Atacama Desert is the Caleta el Cobre 022 nakhlite, which stands out among nakhlites for its unusually high abundance of Martian aqueous alteration products (Krämer Ruggiu et al., 2020).

There is a significant difference in the abundances of stony achondrites in the Atacama Desert and worldwide collection (1.0 ± 0.4% and 7.1 ± 0.2%, Figure 2). Commonly, surfaces in the Atacama Desert are covered by cm-to-mm rocks mainly of igneous origins: plutonic, volcanic, and pyroclastic rocks. Their typical colors are red, brown, or black, which do not contrast with potential stony achondrites and could influence the Atacama collection statistics. Also, the high percentage of stony achondrites in the worldwide collection, particularly from hot deserts, could be biased by dealers focusing on finding stony achondrites due to the high price they can reach in the market. The latest is the case of the NWA collection and could also affect the Atacama collection because 26 of the 29 Atacama stony achondrites were found by private meteorite hunters. Yet, the worldwide collection is dominated by Antarctic meteorites (~60%), mostly found by systematic searches carried out by research groups who classify all specimens.

### Chondrites

Among all the meteorites, OCs dominate the population with almost 94.7 ± 0.8% (N = 2621; Figure 2a) of the finds, well above the worldwide value of 84.8 ± 0.3%, while carbonaceous and enstatite chondrites representing only 1.7 ± 0.5% (N = 46) and 0.2 ± 0.2% (N = 6) of the finds, respectively (below worldwide values of 4.2 ± 0.1% and 0.9 ± 0.1%, respectively). Only one Rumuruti chondrite (R4-an) has been found in the
<figure><img src="image_2.png" /><figcaption>FIGURE 1. In situ pictures of Atacama meteorites and surface properties on Pampa de Mejillones (a), Paposo (b), Cariquima (c), Caleta el Cobre (d), El Médano (e), Imilac (f), Los Vientos (g), Catalina (h), Vaca Muerta (i), and Calama (j). Pictures were provided by the *Museo del Meteorito* (San Pedro de Atacama, Chile). (Color figure can be viewed at wileyonlinelibrary.com)</figcaption></figure>
Atacama, whose olivine displays a lower Fa content compared to the typical Rumuruti chondrites (Meteoritical Bulletin Database, as of June 2023).

The 2621 OCs from the Atacama Desert show a relative abundance of $55.4 \pm 1.9\%$ ($N=1453$), $39.8 \pm 1.9\%$ ($N=1043$), and $4.4 \pm 0.8\%$ ($N=116$) for H, L, and LL, respectively, with a high and low abundance of H and LL chondrites compared to the worldwide collection ($44.6 \pm 0.4\%$ and $13.3 \pm 0.3\%$, respectively). The remaining OCs ($0.3 \pm 0.2\%$, $N=9$) have been classified as mixed groups (e.g., H-L or L-LL) from their petrographic (brecciated texture) or chemical characteristics. Only L chondrites display similar abundance ($39.8 \pm 1.9\%$) compared to the worldwide collection ($42.1 \pm 0.4\%$). The most abundant petrologic types are H5 and L6 that make up $62.6 \pm 2.5\%$ and $68.4 \pm 2.8\%$, respectively, of their respective group (Figure 3b,c). These values are slightly higher than the worldwide values of $47.8 \pm 0.7\%$ and $49.3 \pm 0.7\%$ for H5 and L6, respectively. In the Atacama Desert, LL6 is the most abundant petrologic type of LL chondrites by number ($49 \pm 9.6\%$; $N=51$), but LL3-4 leads the mass distribution with an abundance up to $66 \pm 3.3\%$ ($N=16$; Figure 3a). In the worldwide collection LL5 lead by number ($47.8 \pm 1.2\%$; $N=3189$) and LL6 by mass ($38.4 \pm 0.6\%$).

As H and L chondrites are the most abundant meteorites in all collections, different studies used the H/L ratio to constrain atmospheric/weathering fragmentation and/or change in the extraterrestrial flux material to the Earth over time (Benoit & Sears, 1996; Gattacceca et al., 2011; Kouvatsis & Hofmann, 2020). The H/L ratio is $0.87 \pm 0.06$ for worldwide falls, but it is slightly higher for Antarctica and Non-Antarctica finds, $1 \pm 0.01$ and $1.1 \pm 0.02$, respectively (Table 1). In the case of Atacama Desert chondrites, the mean H/L ratio is even higher ($1.4 \pm 0.05$), but it fluctuates notably among DCAs (see Table 1). Drouard et al. (2019) suggested that H chondrites dominated the flux between 1.2 and 0.4 Ma, and due to the long-standing preservation of Atacama surfaces (Dunai et al., 2005), the H/L values in Atacama DCAs integrated past variations of extraterrestrial material flux on Earth. It should however be noted that the H/L parameter could be strongly modified by (i) the pairing process of meteorite showers and (ii) local fragmentation during weathering (Ashley & Velbel, 2000; Kouvatsis & Hofmann, 2020).

Among the 46 carbonaceous chondrites (CCs) found on the Atacama surfaces, the CO group is the most abundant ($60.9 \pm 14.1\%$; Figure 2). For comparison, the CO worldwide abundance is only $24.3 \pm 1.5\%$ (Meteoritical Bulletin Database, as of June 2023). The overabundance of CO chondrites in the Atacama Desert may be related to the lack of pairing processes of individual fragments among Atacama DCAs. For instance,

petrographic description and physical parameters (i.e., magnetic susceptibility and density) of 11 CO chondrites found at El Médano DCA indicate a likely meteorite shower. Further analyses are necessary to explore the pairing of meteorite showers in different Atacama DCAs. It must be underlined that no CM chondrites have been found in the Atacama Desert, which contrasts with the large number of specimens reported in the worldwide collection ($24.3 \pm 1.5\%$, Meteoritical Bulletin Database, as of June 2023). We hypothesize that CM chondrites could be easily altered by weathering agents in the Atacama Desert. Thermoclastic weathering and the pervasive salt infiltration from the Atacama soils could speed up the fragmentation and erosion of chondrites with a high modal abundance of fine-grained matrix, such as CM and CI chondrites.

## DCAS IN THE ATACAMA DESERT

### Geological Context

Thirty-five DCAs have been defined by the Meteoritical Society in the Atacama Desert (Figure 4), three of them (Caleta Coloso, Palestina, and Agua Buena) having no meteorite reported yet. The Atacama DCAs are located between 21°15′ to 26°30′S latitude and 70°30′ to 67°30′W longitude (i.e., concentrated in the Antofagasta region) and in between four North–South morphotectonic units: the Coastal Range (CR), the Central Depression (CD), the Pre-Andean Range, and the Pre-Andean Basement. The CR has a width of ~50 km and a maximum altitude of 2000 m. Its meteorological conditions are defined as semiarid, because of the direct influence of a coastal fog (locally known as *camanchaca*), which, under favorable topographic conditions, penetrates up to 50–90 km inland (e.g., Goudie et al., 2002; Rech et al., 2003). The CD is a hyperarid subregion almost completely devoid of vegetations, protected from the coastal fog influence by the CR to the west and from seasonal rainfalls by the Andean Cordillera to the east. Surfaces are filled with Tertiary and Quaternary alluvial, fluvial, and evaporitic deposits mainly derived from the Pre-Andean range and Western Andean Cordillera. In order to simplify the climatic description and their link to meteorite alteration and considering the extent of the Pre-Andean Range and Pre-Andean Basement, we combine them both in a single unit referred as the Pre-Andean Range/Basement (PRB). The PRB unit comprises the Cordillera de Domeyko, a N-S mountain range 600 km long with maximum altitude of ~4000 m and intermontane basins and salt flats, a series of Cenozoic depocenters created by reverse faulting of kilometer-scale bounded by the Domeyko Cordillera and the current Western Andean Cordillera (Amilibia et al., 2008;
<figure><img src="image_3.png" /><figcaption>(b) World collection</figcaption></figure>

<figure><img src="image_4.png" /></figure>
FIGURE 2. Relative abundances by groups of meteorites found in the Atacama Desert (a) and the world collection (b). The relative abundance within carbonaceous chondrite and iron meteorite populations by number are shown on the right side of each collection. Non-magmatic irons are indicated in yellow. The main groups are ordinary chondrites, carbonaceous chondrites, enstatite chondrites, irons, achondrites (primitive and planetary achondrites), stony-irons (N = 11), and ungrouped chondrites including Rumuruti and Kakangari chondrites. (Color figure can be viewed at wileyonlinelibrary.com)

<figure><img src="image_5.png" /></figure>

FIGURE 3. Histogram of the mass distribution of 2481 OCs from the Atacama Desert by petrologic type 3–4 (a), type 5 (b), and type 6 (c). Brecciated OCs with more than one petrologic type and/or chemical classification (e.g., L/LL4) were excluded. L6, H5, and LL6 lead the mass distribution by petrologic type with 709.7, 647, and 37.6 kg, respectively. The last bin in each histogram displays all the OCs with masses larger than 2000 g. (Color figure can be viewed at wileyonlinelibrary.com)

Arriagada et al., 2006; Martínez et al., 2021 and references therein). Eleven Atacama DCAs belong to the CR unit, thirteen DCAs belong to the CD unit, and eight DCAs belong to the PRB unit (Table 2). For instance, the abundance of OCs is greater in the CD unit (54.8 ± 1.9%, N = 1435) followed by the CR (27 ± 1.7%, N = 708) and PRB units (18.2 ± 1.5%, N = 478).

The nature of the surfaces of the Atacama DCAs depends on the morphotectonic units that are present locally. It is essential to mention that only a fraction of the DCA surface is suitable for finding meteorites. Nonproductive parts include steep mountains, cliffs, and shores. The optimal surfaces are preferentially located on flat extended plains of mild slopes (<2°) developed mainly on Tertiary and Quaternary colluvium and alluvium with few (if any) exposed rock outcrops. These surfaces consist mainly of non-consolidate material, including gravels,

<table><caption>TABLE 1. The abundance of H and L chondrite statistics for the main Atacama DCAs compared to worldwide falls and finds.</caption><thead><tr><th>DCA</th><th>H</th><th>L</th><th>H/L</th><th>Error H/L<sup>a</sup></th></tr></thead><tbody><tr><td>Catalina</td><td>331</td><td>169</td><td>1.96</td><td>±0.12</td></tr><tr><td>Calama</td><td>238</td><td>156</td><td>1.53</td><td>±0.12</td></tr><tr><td>Chug Chug</td><td>87</td><td>75</td><td>1.16</td><td>±0.17</td></tr><tr><td>El Médano</td><td>290</td><td>173</td><td>1.68</td><td>±0.12</td></tr><tr><td>Los Vientos</td><td>256</td><td>193</td><td>1.33</td><td>±0.11</td></tr><tr><td>Sierra Gorda</td><td>44</td><td>87</td><td>0.51</td><td>±0.12</td></tr><tr><td>All Atacama</td><td>1453</td><td>1041</td><td>1.39</td><td>±0.05</td></tr><tr><td>Worldwide falls</td><td>394</td><td>452</td><td>0.87</td><td>±0.06</td></tr><tr><td>Antarctica finds</td><td>17,748</td><td>17,069</td><td>1.04</td><td>±0.01</td></tr><tr><td>Non-Antarctica finds</td><td>9019</td><td>8131</td><td>1.11</td><td>±0.02</td></tr></tbody></table>

and/or pebbles primarily made of igneous and sedimentary rock fragments such as andesite, dacite, ignimbrite, gabbro, granodiorite, diorite, conglomerate, and sandstone (Espinoza et al., 2011; Marinovic et al., 1995).

## Climatic Conditions

Three main factors modulate the precipitation deficit in the Atacama Desert: (i) a constant temperature inversion generated by the cold north-flowing Peruvian Current in the Pacific Ocean, (ii) the rain shadow effect produced by the proximity of the high Andes, and (iii) its location in the subtropical high-pressure belt (Clarke, 2006; Grosjean et al., 2003; Latorre et al., 2003; Marquet et al., 1998; Rundel et al., 1991). The climatic conditions in each DCA show significant variations along W-E transects perpendicular to the Andes and across the distinct morphotectonic units. These variations depend on the distance from the Pacific Ocean, which can generate dense coastal fog and topographic elevation, which controls the precipitation rate among the different morphotectonic units (Boy et al., 2022). Experimental studies show that metal corrosion in OCs is mostly controlled by thermoclastic weathering produced by temperature fluctuations during day/night and high level of humidity (Van Ginneken et al., 2022). Both are common factors in the Atacama Desert, with slightly major level of humidity in CR. Additionally, surfaces in

<footnote><sup>a</sup>Estimated uncertainty using a 95% confidence interval and assuming a Poisson distribution of the H and L chondrites.</footnote>
<figure><img src="image_6.png" /><figcaption>FIGURE 4. The 35 DCAs defined by the Meteorological Society in the Atacama Desert, with the number of collected meteorites in panel (a), and the map of the three morphotectonic units described in this article with each DCA indicated by number in panel (b). La Yesera and Pampa de Mejillones DCAs were merged to the PMY DCA (number 31). (Color figure can be viewed at wileyonlinelibrary.com)</figcaption></figure>

the CD normally display a mm-to-cm layer consisting of precipitated saline minerals such as sulfates, halides, chromates, and borates (Ericksen, 1981). The interactions with H₂O and the salty soils control the pervasive saline obliteration of Atacama chondrites via production of µm-to-mm secondary veins and/or porosity filled by nitrate or sulfate precipitates (Pinto et al., 2022; Pourkhorsandi et al., 2017; Valenzuela, 2011). The higher proportion of meteorites in the CD indicates favorable preservation conditions where a protective climate screen limits precipitation from the east and west. Many of these surfaces exhibit ventifacts and well-developed desert pavements, which result from an efficient deflation process.

## TERRESTRIAL WEATHERING AND THE INFLUENCE OF DCA LOCATION

Although numerous DCAs have been recently discovered in the Atacama Desert (e.g., Hutzler et al., 2016; Pastukhovich et al., 2018), a detailed physical and climatic characterization is yet to be made to constrain

the relationship with chondrite weathering. In this section, we discuss the terrestrial alteration of chondrites in the Atacama Desert compared to other desert collections. We subsequently discuss variations between the main Atacama DCAs.

### Chondrites in the Atacama Desert and Other Collections

Since OCs represent ~95% of meteorites in the Atacama Desert (Figure 3), the following discussion will focus on this type of meteorites using the weathering scale ranging from W0 to W6 (Wlotzka, 1993). Chondrite finds have different weathering trends depending on the location where they were recovered in the world. The distribution of weathering grades for the Atacama Desert, other hot deserts, and Antarctic OCs is shown in Figure 5. Compared to the Atacama Desert, OCs from the Sahara Desert (i.e., NWA, Algeria, Libya, Tunisia, Morocco, and Egypt; Figure 5) show similar values for W2 (36.6%), but a lower portion of W1 (28%). Among other hot deserts, OCs from China show a similar weathering distribution to that of Saharan chondrites, while Oman and Iran OCs are more
<table><caption>TABLE 2. Weathering of ordinary chondrites in all DCAs from the Atacama Desert.</caption><thead><tr><th>Geomorphologic unit</th><th>DCA</th><th>N chondrites</th><th>W0</th><th>W1</th><th>W2</th><th>W3</th><th>W4</th><th>W5</th><th>Others</th></tr></thead><tbody><tr><td rowspan="10">Coastal range</td><td>Pampa de Mejillones</td><td>25</td><td></td><td>1</td><td>5</td><td>4</td><td>6</td><td>3</td><td>6</td></tr><tr><td>La Yesera</td><td>4</td><td></td><td></td><td>1</td><td>2</td><td>1</td><td></td><td></td></tr><tr><td>Caleta el Cobre</td><td>63</td><td>2</td><td>23</td><td>12</td><td>17</td><td>6</td><td></td><td>3</td></tr><tr><td>El Médano</td><td>493</td><td>4</td><td>117</td><td>175</td><td>156</td><td>32</td><td></td><td>9</td></tr><tr><td>Paposo</td><td>78</td><td>1</td><td>33</td><td>27</td><td>14</td><td></td><td>1</td><td>2</td></tr><tr><td>Mantos Blancos</td><td>1</td><td></td><td></td><td></td><td>1</td><td></td><td></td><td></td></tr><tr><td>Las Bombas</td><td>2</td><td></td><td></td><td>2</td><td></td><td></td><td></td><td></td></tr><tr><td>Diego de Almagro</td><td>2</td><td></td><td></td><td>2</td><td></td><td></td><td></td><td></td></tr><tr><td>Calate</td><td>31</td><td></td><td></td><td>7</td><td>9</td><td>12</td><td>1</td><td>2</td></tr><tr><td>Coya Sur</td><td>8</td><td></td><td>2</td><td></td><td>2</td><td>3</td><td></td><td>1</td></tr><tr><td>Taltal</td><td>1</td><td></td><td>1</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Total</td><td></td><td>708</td><td>7</td><td>177</td><td>231</td><td>205</td><td>60</td><td>5</td><td>23</td></tr><tr><td rowspan="15">Central depression</td><td>Altamira</td><td>2</td><td></td><td></td><td>1</td><td>1</td><td></td><td></td><td></td></tr><tr><td>San Juan</td><td>109</td><td></td><td></td><td>37</td><td>38</td><td>28</td><td>3</td><td>3</td></tr><tr><td>Catalina</td><td>540</td><td>2</td><td>226</td><td>196</td><td>82</td><td>18</td><td></td><td>16</td></tr><tr><td>Los Vientos</td><td>463</td><td>3</td><td>181</td><td>166</td><td>81</td><td>20</td><td>2</td><td>10</td></tr><tr><td>Baquedano</td><td>1</td><td></td><td></td><td></td><td>1</td><td></td><td></td><td></td></tr><tr><td>Rencoret</td><td>1</td><td></td><td></td><td></td><td>1</td><td></td><td></td><td></td></tr><tr><td>Chug Chug</td><td>170</td><td>1</td><td>94</td><td>45</td><td>25</td><td>3</td><td></td><td>2</td></tr><tr><td>Sierra Gorda</td><td>137</td><td></td><td>49</td><td>55</td><td>23</td><td>4</td><td></td><td>6</td></tr><tr><td>Vaquillas</td><td>6</td><td></td><td>2</td><td>1</td><td>2</td><td></td><td></td><td>1</td></tr><tr><td>Carrizo</td><td>1</td><td></td><td></td><td></td><td>1</td><td></td><td></td><td></td></tr><tr><td>Agua de Varas</td><td>1</td><td></td><td></td><td></td><td>1</td><td></td><td></td><td></td></tr><tr><td>Quebrada Chimborazo</td><td>1</td><td></td><td></td><td></td><td></td><td></td><td></td><td>1</td></tr><tr><td>Coipuno</td><td>3</td><td></td><td>3</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Total</td><td></td><td>1435</td><td>6</td><td>592</td><td>502</td><td>246</td><td>48</td><td>2</td><td>39</td></tr><tr><td rowspan="10">Pre-Andean Range/Basin</td><td>Imilac</td><td>3</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Cerro Quimal</td><td>1</td><td></td><td>1</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Limon Verde</td><td>31</td><td>1</td><td>14</td><td>10</td><td>4</td><td>2</td><td></td><td></td></tr><tr><td>Calama</td><td>405</td><td></td><td>115</td><td>174</td><td>95</td><td>15</td><td></td><td>6</td></tr><tr><td>Machuca</td><td>29</td><td></td><td>21</td><td>8</td><td></td><td></td><td></td><td></td></tr><tr><td>Toconao</td><td>7</td><td></td><td>1</td><td>4</td><td>2</td><td></td><td></td><td></td></tr><tr><td>Colachi</td><td>1</td><td></td><td></td><td></td><td>1</td><td></td><td></td><td></td></tr><tr><td>Tilomonte</td><td>1</td><td></td><td></td><td></td><td>1</td><td></td><td></td><td></td></tr><tr><td>Total</td><td></td><td>478</td><td>1</td><td>152</td><td>198</td><td>104</td><td>17</td><td>0</td><td>6</td></tr></tbody></table>

altered with common W3-4 grades that largely affect their petrographic and chemical characteristics (Pourkhorsandi et al., 2019; Zurfluh et al., 2016). It is important to emphasize that metal alteration to limonite is faster in kamacite than in taenite for OCs, and as H chondrites display a high taenite/kamacite ratio, it should be altered more easily than L or LL chondrites (Ikeda & Kojima, 1991). In this sense, the distribution of the weathering index shown in Figure 5 could be potentially biased because regions have different H/L ratios. However, this effect is discarded given that there is no correlation between the H/L ratio and the weathering index mode of chondrites among the main Atacama DCAs (Tables 1 and 2). In the case of Antarctic OCs, the most common weathering grade is W1 (55%), followed by W2 (37.6%). Although no hot desert presents an abundance of W1 as large as Antarctic chondrites, the Atacama collection

shows the closest distribution with 36.1% and 36.5% of chondrites graded as W1 and W2, respectively (Figure 5). Nevertheless, the low weathering grade of OCs from the Atacama could be influenced by dealers and curators who mostly focus on and classify the least weathered meteorite specimens. This is also true for NWA, but possibly not for the meteorite collections of Oman and the Sahara, whose meteorites were mostly carried out by research groups who classified all specimens to determine accurate statistical information. The greater preservation of Antarctic chondrites comes from their protection against alteration agents when they are buried in the ice (Whillans & Cassidy, 1983). For instance, the precipitation of evaporite minerals such as calcium sulfate [CaSO₄·2H₂O] is triggered by humidity in a saline environment and/or fluid circulation coming from the soil. In the case of Antarctic chondrites, only ~5% show evidence of evaporite mineral
<figure><img src="image_7.png" /><figcaption>FIGURE 5. Distribution of the weathering grade, according to Wlotzka (1993) classification, for OCs from the Atacama Desert, other hot deserts, and the Antarctic collection (Meteoritical Bulletin Database, as of June 2023). (Color figure can be viewed at wileyonlinelibrary.com)</figcaption></figure>

precipitation (Losiak & Velbel, 2011), whereas it is common in Atacama meteorites (Pinto et al., 2022; Valenzuela, 2011).

Due to important terrestrial weathering, it has been reported that samples from hot deserts should be used with caution for some chemical and isotopic analyses. However, the samples from the Atacama Desert are characterized by better conservation states compared to those from other geographic locations (Figure 5). Pourkhorsandi et al. (2022) interpreted that the Sm-Nd isotopic deviation and rare earth element (REE) abundances’ modification of hot desert chondrites result from terrestrial alteration induced by the contamination by terrestrial fluids with soil interaction and the leaching of chondritic components such as Ca-phosphates. However, both alteration processes should have only slightly affected the bulk oxygen isotopic composition of Atacama chondrites (based on the few reported O-isotopic data in the Meteoritical Bulleting database, 2023), when we compare to the O-isotopic shift reported in other areas worldwide (Bischoff et al., 2022; Greenwood et al., 2012). Within the Atacama chondrites, metal and sulfide grains are the main phases that show significant signs of alteration by terrestrial fluid percolation, suggesting that silicates and calcium-aluminum-rich inclusions (CAIs) likely preserve their original O isotopic compositions acquired upon condensation/crystallization. The limited extent of the alteration of silicates and CAIs is also supported by recent weathering experimental results in chondrites (Van Ginneken et al., 2022). Applying a range of temperatures and humidity levels on polished sections of the H5 chondrite Asuka-10177, the experiments revealed extensive weathering of the Fe-Ni metal grains, but only a minor

alteration of troilite and no evidence of mafic silicate alteration. The overall good preservation of Atacama chondrites is further attested by (i) the similar ¹⁶O-rich isotopic composition of Los Vientos 051 among the newly defined CL group (Metzler et al., 2021) and (ii) similar O-isotopic compositions of olivine and pyroxene crystals in Sierra Gorda 009 and Grosvenor Mountains (GRO) 95551, coming from Atacama and Antarctica, respectively (Ivanova et al., 2020). However, in terms of isotopic compositions, highly weathered Antarctic meteorites still exhibit less variability compared to meteorites from hot deserts (Maeda et al., 2021; Pourkhorsandi et al., 2022).

Although the preservation of Atacama chondrites is remarkable compared to other hot deserts, the processes responsible for weathering fragmentation seem to be similar (Al-Kathiri et al., 2005; Figure 6). It starts when the meteorite fell with a fresh fusion crust (total or partial) on the Atacama surfaces. Depending on the surface properties and the speed of the meteoroid, extraterrestrial fragments can either become buried underground or remain on the superficial layer. In both cases, the meteorite initiates reactions with H₂O in a vapor form and with salts from the soil, such as sulfates or nitrates (Figure 6a). Subsequently, the thermoclastic weathering, wind abrasion, metal oxidation, and salt precipitations generate internal pressure, ultimately causing the formation of secondary fractures and fragmentation along shock veins, preexisting fractures or other zones of weakness (Figure 6b). Prolonged exposure to these weathering agents leads to the complete breakdown of the meteorite into smaller pieces, which may further disintegrate over time (Figure 6c). For instance, the efficient mechanism of meteorite disintegration in the Atacama Desert is evidenced by the common in situ local fragmentation of chondrites in Calama, Catalina, and Los Vientos DCAs (Figure 2j). Microbiological factors have also been demonstrated to be an important promoter of chondrite alteration and fragmentation (Bland et al., 2006; Lee et al., 2017; Tait et al., 2017). However, microbiological colonization of Atacama meteorites is still poorly understood.

The greater alteration shown by some Atacama meteorites is likely related to their older terrestrial ages. Indeed, terrestrial ages of Atacama meteorites can reach up to ~2 Ma (Drouard et al., 2019), with a similar distribution than Antarctic chondrites (2000 years to 1 Ma; Nishiizumi et al., 1989) but much older than other hot deserts that have an average of ~12 ka (Drouard et al., 2019; Jull et al., 2013). Old terrestrial ages induce soil contamination of chondrites, which increases the concentration of Sr, Ba, and light REEs (e.g., Sm, Nd, Ce, and La) up to eight times compared to the baseline composition of fall meteorites (Pourkhorsandi et al., 2017). However, terrestrial ages and the stated alteration
<figure><img src="image_8.png" /></figure>

FIGURE 6. Schematic representation of the meteorite residence in the Atacama Desert. (a) Meteorite fell and initiates the reactions with H₂O and salts, such as sulfates or nitrates. (b) Different weathering agents modify the meteorite characteristics. (c) Prolonged exposure of the meteorite in the Atacama Desert, which produce local fragmentation and rusty aspect over time. (Color figure can be viewed at wileyonlinelibrary.com)

products of chondrites have been characterized in only a handful of Atacama surfaces (El Médano, Caleta el Cobre, Los Vientos, San Juan, Catalina and Pampa de Mejillones; Drouard et al., 2019; Gattacceca et al., 2011; Hutzler et al., 2016; Pourkhorsandi et al., 2017). In the next section, we will examine the weathering patterns in chondrites from Atacama DCAs, considering their morphotectonic context and the current climatic conditions of the surfaces.

## Suitable Areas for Meteorite Preservation in the Atacama Desert

The highest abundance of weathered OCs is found in the CR surfaces (29.9% with W3; Table 2). In comparison, the CD holds the more significant abundance of slightly

altered OCs (42.4% with W1), and the PRB is characterized by a high abundance of W2 (42%). As the oldest surfaces are distributed from W to E in the Atacama Desert, the weathering degree distribution of chondrites seems not to be correlated with the surface age but rather with the regional/subregional climatic condition (e.g., Munayco et al., 2013).

We selected 13 DCAs with more than 20 meteorites for a detailed description and subsequent morphogenetic characterization. Among these areas, five belong to the CR, five to the CD, and three to the PRB (Table 2). The areas with the larger abundance of meteorites in the CR, CD, and PRB are El Médano (N = 493), Catalina (N = 540), and Calama (N = 405), respectively. The OCs found in Machuca, Chug Chug, and Limon Verde have the larger fraction of W1 (72.4%, 56% and 45.2%, respectively), whereas severely weathered chondrites (W5) are only found on the CR surfaces of Pampa de Mejillones (15.8%), Calate (3.5%), and Paposo (1.3%). The most altered meteorites are found in the productive surface of Pampa de Mejillones, which is located at low altitudes (ranging from 50 to 80 m above sea level) along the Pacific Ocean and is affected on a daily basis by a dense ocean fog. The latest has also been attested by their highly fractionated REEs (Pourkhorsandi et al., 2017). On the other hand, 21 out of 29 chondrites in the Machuca DCA (~3100 m above sea level) have been classified as W1 and the remaining as W2 (Table 2). This result is probably biased by a large L5 strewn field with many W1 stones (Meteoritical Bulletin Database, as of June 2023), which is supported by the small H/L ratio (~0.2) in the Machuca DCA.

In order to construct a morphogenetic classification (Peltier, 1950) of the Atacama DCAs, we extracted climatic information from TerraClimate (Abatzoglou et al., 2018) using the Google Earth Engine platform (Gorelick et al., 2017). A posteriori verification of TerraClimate data was performed using meteorological stations of the Dirección General de Aguas (https://www.cr2.cl/) in Northern Chile at a climatic scale (comparison on annual data). The verification of various climate models has enabled to estimate uncertainty in temperature and precipitations derived from TerraClimate, which were incorporated into a Monte Carlo process that generates morphogenetic classification points through 50,000 iterations of convergence. The morphogenetic classification of the CR, CD, and PRB units as well as the main DCAs are shown in Figure 7. The annual temperature and precipitations for the 13 selected DCAs are estimated as the mean of the pixels located in the productive areas (i.e., areas where meteorites were found; Table S1). The morphogenetic hyperarid zone is defined by a ratio of annual precipitations to potential annual evaporation of <0.05 (https://wedocs.unep.org/20.500.11822/30300). Using
the Köppen climatic classification (Köppen, 1884), we distinguish two hyperarid regimes in the Atacama Desert:

i. a winter regime where the precipitation regime *P* has a linear relationship with temperature *T*:

$$T [^{\circ}\text{C}] = P [\text{mm}] \qquad (1)$$

ii. a summer regime where the precipitation regime *P* shows an affine relationship with temperature *T*:

$$T [^{\circ}\text{C}] = P [\text{mm}] - 14 \qquad (2)$$

The main precipitation regime in the geographical area under consideration is a winter regime, although there is the possibility of a non-systematic summer regime (Bolivian winter or Altiplanic winter), which affects principally the PRB morphotectonic zones. In the morphogenetic classification diagram, the hyperaridity limit is slightly shifted to the right during the summer regime due to the increased summer evapotranspiration.

Our analysis shows that in both regimes, (i) the CR unit is mainly hyperarid, (ii) the CD unit is mainly hyperarid with few surfaces in the arid domain and a change of this arid domain into a summer hyperarid regime, and (iii) the PRB unit corresponds to arid and periglacial conditions with some summer hyperarid surfaces (Figure 7). Our analyses show that in the winter regime, 61.5% of DCAs are in the hyperarid zone, while 38.5% are characterized by an arid regime. These numbers change to 76.9% and 23.1% if the summer hyperarid regime is considered. This result agrees with the climatic characterization of the first DCAs in the Atacama Desert, Pampa de Mejillones, San Juan, and El Médano (Gattacceca et al., 2011; Hutzler et al., 2016; Valenzuela, 2011). Overall, all DCAs have an annual mean air temperature ranging from 11 to 19°C and annual cumulative precipitation between 10 and 40 mm (orange dashed square in Figure 7). All the areas in the PRB (Limon Verde, Machuca and Calama) display the highest annual precipitations and the lowest temperatures (i.e., up to 40 mm and no more than 14°C). On the other hand, high median weathering (W4) is displayed by Pampa de Mejillones and Calate DCAs, which are characterized by elevated temperatures (>18°C) and low annual precipitations (<~10 mm). Although coastal fog plays a relevant role in altering chondrites on CR surfaces, it is not associated with the precipitation variable. Therefore, the morphogenetic classification cannot explain the differences in alteration grades of OCs in CR areas based only on local temperature and precipitations. The use of other atmospheric variables such as relative humidity, specific humidity, or dew point should be taken into account in

order to characterize the specific role of the coastal fog in the alteration of meteorites.

Our analysis reveals that DCAs with a large abundance of meteorites tend to show similar climatic conditions even if they belong to a different morphotectonic units. For instance, Los Vientos, Catalina, El Médano, Paposo, and Caleta el Cobre share the same climatic context and are the most productive surfaces in the Atacama Desert (see Figure 7). Chug Chug and Sierra Gorda DCAs also display a similar climatic context with slightly higher values of annual precipitations. The latter two areas accumulate all the meteorites (except Sierra Gorda 001) in the same “hanging” surface located between two deep canyons, and the division between these two DCAs has been set arbitrarily at latitude 22°30'S. We estimated the abundance of meteorites in the “hanging” surface area and calculated a density of 1 meteorite km⁻², encompassing both the Chug Chug and Sierra Gorda DCAs. As the size of each DCA should depend on the geographic conditions of the region, we defined new polygons for the 13 DCAs enclosing only the productive surfaces (areas with find meteorites). Our analysis reveals that, on average, only 31.3% of the quadrants defined for each Atacama DCA are truly advantageous surfaces for searching meteorites (Table S1). Although tiny DCAs have been defined worldwide (e.g., dry lakes in the USA), most of them and the more productive ones are the larger areas (e.g., Chile, Oman, and China). Finding a local name (e.g., mountains, train stations, and lakes) could represent a challenge to define an adequate label for a new confined DCA. In this sense, we recommend considering a precise definition of the surfaces of interest and not necessarily the official DCA limits. The former is particularly essential for (i) the estimation of meteorite abundances, (ii) the pairing of large strewn fields, and (iii) understanding the local climatic conditions that affect the preservation of meteorites.

The Atacama chondrites make up the oldest collection of non-fossil meteorites with a mean terrestrial age of 710 ka (Drouard et al., 2019). Although our morphogenetic classification of Atacama DCAs is based on present-day climatic conditions, the Atacama surfaces are characterized by a long-standing hyperaridity, possibly during the last 10 Ma (Clarke, 2006; Dunai et al., 2005; Rech et al., 2006). In this sense, the weathering degree of Atacama meteorites could (i) integrate the past climatic conditions in the Atacama Desert, which, while still arid, could have episodically been more humid than today or (ii) mainly represents the initial climatic conditions at the time of the meteorite landing and then be only affected by local factors such as sporadic rainfall events or daily coastal fog influences. Placzek et al. (2010) sampled cosmogenic nuclides (²⁶Al and ¹⁰Be) from granitic and andesitic rocks in bedrock, boulders, and sediments (in alluvial and active surfaces) along a transect
<figure><img src="image_9.png" /><figcaption>FIGURE 7. (a) Morphogenetic classification of Atacama DCAs (number refers in Figure 5b) using the average reconstructed annual temperature and precipitation. Boundaries of arid, semiarid, and periglacial zones are from Peltier (1973). The hyperarid zone corresponds to the boundaries defined by the United Nations Environment Programme (https://wedocs.unep.org/20.500.11822/30300). The dashed line shows the summer precipitation regime calculated from Equation (2). The average annual temperature and precipitation in the 13 DCAs were estimated as the mean of the pixels located only in the productive zones and are zoomed in (b). We plot only DCAs with more than 20 meteorites. The solid color lines represent kernel density estimates (KDEs) at 50% for the climatic data in each morphogenetic unit of the Atacama Desert. For each DCA, we represent the density (abundance) of meteorites with different circle sizes and colors referring to the median alteration grade: blue = W1, green = W2, and orange = W4. The color of each DCA number represents the morphogenetic unit of location. The orange dashed lines display where all the Atacama DCAs are located. CD, central depression; CR, coastal range; and PRB, Pre-Andean range/Basement. (Color figure can be viewed at wileyonlinelibrary.com)</figcaption></figure>

extending from the Pacific coast to the Andean foothills in the Atacama Desert. Their results reveal a minimum exposure age between 0.39 and 1.57 Ma for the bedrock

and fluvial sediments in the CD, and between 0.01 and 0.53 Ma for the CR and PRB surfaces. Interestingly, the highest abundance of low-weathering Atacama
chondrites (≤W2) is localized in the CD (78.8%, N=1435), which is also the area with the oldest surfaces in the Atacama Desert. This agrees with an extensive compilation of cosmogenic nuclides analysis of various paleosurfaces in the northern CD (between 18°S and 22°S), which reveals that sediment deposition ceased in different surfaces at approximately 23, 19, 11, 7, and 3 Ma (Evenstar et al., 2017 and references therein). These authors state that the timing of the formation of the individual paleosurfaces in Atacama is influenced by regional climate, while both regional and tectonic activity governs their location. Thus, Atacama DCAs have been controlled by semi-stable climate conditions for hundreds of thousands to millions of years and were impacted primarily during the quaternary by sporadic yet intense rainfall events capable of effectively transporting large boulders (Pfeiffer et al., 2021; Placzek et al., 2010). According to this, weathering patterns in Atacama meteorites represent chiefly the initial climatic conditions of the surface where they fell, and to a lesser degree the effects of local atmospheric factors such as sporadic rainfall events or daily coastal fog influences.

## CONCLUDING REMARKS

The DCAs for meteorite recovery in the Atacama Desert were characterized by their climatic and geological context considering three main morphotectonic units: the CR, CD, and PRB. A comparison with reported weathering data from other cold and hot deserts indicates that the mean terrestrial weathering of Atacama chondrites (W1–2) is lower than that of other hot deserts (W2–3) and resembles that of the Antarctic meteorites (W1–2). However, the mean weathering degree of Atacama chondrites changes according to the regional/subregional climatic conditions of the DCAs. The highest abundance of low-weathering Atacama chondrites (≤W2) is localized in the CD (78.8%, N=1435), followed by the PRB units (74.4%, N=478). The CR, which suffers high average of annual temperatures and the influence of coastal fog, has the most significant abundance of high-weathered chondrites (W4–5; 9.5%, N=708). Our morphogenetic classification of the main Atacama DCAs reveals the following:

1. A similar hyperarid to arid conditions in the most productive surfaces for meteorite recovery, which are associated into four groups: (i) Los Vientos, Catalina, El Médano, Paposo, and Caleta el Cobre; (ii) Pampa de Mejillones and Calate; (iii) Chug Chug and Sierra Gorda; and (iv) Calama and Limón Verde.

2. On average, about 31.3% of the quadrangles defined for each Atacama DCA are suitable surfaces for searching meteorites.

3. Only the temperature and precipitations cannot explain the differences in weathering patterns observed in meteorites.

Potential studies of chondrite preservation in the Atacama DCAs should consider other meteorological variables such as relative humidity, specific humidity, or dew point and keep a continued implementation of the data set on surface exposure ages of DCA surfaces and meteorite terrestrial ages.

*Acknowledgments*—We are grateful to Rodrigo Martínez for all the discussion and the pictures of Atacama meteorites in situ. We are thankful for the comments of the reviewers (L. Folco and R. Maeda) that helped improve this manuscript. G.A.P. and F.O.E. acknowledge support from FONDECYT project 1201223. G.A.P. was supported by the Eiffel excellence scholarship (grant 968045D).

*Conflict of Interest Statement*—We have no conflicts of interest to disclose. All authors declare that they have no conflicts of interest.

*Data Availability Statement*—The data that support the findings of this study are available from the corresponding author upon reasonable request.

*Editorial Handling*—Dr. A. J. Timothy Jull

## REFERENCES

Abatzoglou, J. T., Dobrowski, S. Z., Parks, S. A., and Hegewisch, K. C. 2018. TerraClimate, a Highresolution Global Dataset of Monthly Climate and Climatic Water Balance from 1958–2015. *Scientific Data* 5: 1–12.

Aboulahris, M., Chennaoui Aoudjehane, H., Rochette, P., Gattacceca, J., Jull, A. J. T., Laridhi Ouazaa, N., Folco, L., and Buhl, S. 2019. Characteristics of the Sahara as a Meteorite Recovery Surface. *Meteoritics & Planetary Science* 54: 2908–28. https://doi.org/10.1111/maps.13398.

Acevedo, R. D., Rocca, M., and García, V. M. 2014. *Catalogue of Meteorites from South America*. Heidelberg: Springer. 147.

Al-Kathiri, A., Hofmann, B. A., Jull, A. J. T., and Gnos, E. 2005. Weathering of Meteorites from Oman: Correlation of Chemical and Mineralogical Weathering Proxies ¹⁴C Terrestrial Ages and the Influence of Soil Chemistry. *Meteoritics & Planetary Science* 40: 1215–39. https://doi.org/10.1111/j.1945-5100.2005.tb00185.x.

Amilibia, A., Sàbat, F., McClay, K. R., Muñoz, J. A., Roca, E., and Chong, G. 2008. The Role of Inherited Tectono-Sedimentary Architecture in the Development of the Central Andean Mountain Belt: Insights from the Cordillera de Domeyko. *Journal of Structural Geology* 30: 1520–39. https://doi.org/10.1016/j.jsg.2008.08.005.

Arriagada, C., Cobbold, P. R., and Roperch, P. 2006. Salar de Atacama Basin: A Record of Compressional Tectonics in the Central Andes since the Mid-Cretaceous. *Tectonics* 25: 1–19. https://doi.org/10.1029/2004TC001770.
Ashley, J. W., and Velbel, M. A. 2000. Weathering-Induced Differences in Fragmentation Rates between H and L Ordinary Chondrites as an Explanation for Observed Differences in Antarctic/Non-Antarctic H/L Ratios. *Meteoritics & Planetary Science Supplement* 35: A22.

Benoit, P. H., and Sears, D. W. G. 1996. Rapid Changes in the Nature of the H Chondrites Falling to Earth. *Meteoritics & Planetary Science* 31: 81-86.

Bevan, A. W. R., and Binns, R. A. 1989. Meteorites from the Nullarbor Region, Western Australia: I. A Review of Past Recoveries and a Procedure for Naming New Finds. *Meteoritics* 24: 127-133. https://doi.org/10.1111/j.1945-5100.1989.tb00954.x.

Bischoff, A., and Geiger, T. 1995. Meteorites from the Sahara: Find Locations, Shock Classification, Degree of Weathering and Pairing. *Meteoritics* 30: 113-122. https://doi.org/10.1111/j.1945-5100.1995.tb01219.x.

Bischoff, A., Storz, J., Barrat, J. A., Heinlein, D., Jull, A. J. T., Merchel, S., Pack, A., and Rugel, G. 2022. Blaubeuren, Cloppenburg, and Machtenstein—Three Recently Recognized H-Group Chondrite Finds in Germany with Distinct Terrestrial Ages and Weathering Effects. *Meteoritics & Planetary Science* 57: 136-153. https://doi.org/10.1111/maps.13779.

Bland, P. A. 2001. Quantification of Meteorite Infall Rates from Accumulations in Deserts, and Meteorite Accumulations on Mars. In *Accretion of Extraterrestrial Matter throughout Earth's History*, edited by B. Peucker-Ehrenbrink, and B. Schmitz, 267-303. Boston, MA: Springer. https://doi.org/10.1007/978-1-4419-8694-8_15.

Bland, P. A., Sexton, A. S., Jull, A. J. T., Bevan, A. W. R., Berry, F. J., Thornley, D. M., Astin, T. R., Britt, D. T., and Pillinger, C. T. 1998. Climate and Rock Weathering: A Study of Terrestrial Age Dated Ordinary Chondritic Meteorites from Hot Desert Regions. *Geochimica et Cosmochimica Acta* 62: 3169-84. https://doi.org/10.1016/S0016-7037(98)00199-9.

Bland, P. A., Zolensky, M. E., Benedix, G. K., and Sephton, M. A. 2006. Weathering of Chondritic Meteorites. In *Meteorites and the Early Solar System II*, edited by D. S. Lauretta, and H. Y. McSween, 853-867. Tucson, AZ: University of Arizona Press. https://doi.org/10.2307/j.ctv1v7zdmm.45.

Boy, D., Moeller, R., Sauheitl, L., Schaarschmidt, F., Rapp, S., Brink, L., Gschwendtner, S., et al. 2022. Gradient Studies Reveal the True Drivers of Extreme Life in the Atacama Desert. *Journal of Geophysical Research: Biogeosciences* 127: 1-18. https://doi.org/10.1029/2021jg006714.

Clarke, J. D. A. 2006. Antiquity of Aridity in the Chilean Atacama Desert. *Geomorphology* 73: 101-114. https://doi.org/10.1016/j geomorph.2005.06.008.

Drouard, A., Gattacceca, J., Hutzler, A., Rochette, P., Braucher, R., Bourlès, D., Gounelle, M., et al. 2019. The Meteorite Flux of the Past 2 m.y. Recorded in the Atacama Desert. *Geology* 47: 673-76. https://doi.org/10.1130/G45831.1.

Dunai, T. J., González López, G. A., and Juez-Larré, J. 2005. Oligocene-Miocene Age of Aridity in the Atacama Desert Revealed by Exposure Dating of Erosion-Sensitive Landforms. *Geology* 33: 321-24. https://doi.org/10.1130/G21184.1.

Ericksen, G. E. 1981. Geology and Origin of the Chilean Nitrate Deposits. *US Geological Survey, Professional Paper* 1188: 37.

Espinoza, F., Matthews, S., Cornejo, P., and Venegas, C. 2011. Carta Catalina, Región de Antofagasta. Servicio Nacional de Geología y Minería, Carta Geológica de Chile. *Serie Geología Básica* 129: 63, 1 mapa escala 1:100.000. Santiago.

Evenstar, L. A., Mather, A. E., Hartley, A. J., Stuart, F. M., Sparks, R. S. J., and Cooper, F. J. 2017. Geomorphology on Geologic Timescales: Evolution of the Late Cenozoic Pacific Paleosurface in Northern Chile and Southern Peru. *Earth-Science Reviews* 171: 1-27.

Fan, Y., Li, S., Liu, S., Peng, H., Song, G., and Smith, T. 2022. The Distribution of the Desert Meteorites in China and their Classification. *Meteoritics & Planetary Science* 19: 1-19. https://doi.org/10.1111/maps.13789.

Gattacceca, J., Valenzuela, M., Uehara, M., Jull, A. J. T., Giscard, M., Rochette, P., Braucher, R., et al. 2011. The Densest Meteorite Collection Area in Hot Deserts: The San Juan Meteorite Field (Atacama Desert, Chile). *Meteoritics & Planetary Science* 46: 1276-87. https://doi.org/10.1111/j.1945-5100.2011.01229.x.

Gnos, E., Silvio, L., Otto, E., Timothy Jull, A. J., Hofmann, B. A., Al-Kathiri, A., and Eggimann, M. 2009. The Jiddat al Harasis 073 Strewn Field, Sultanate of Oman. *Meteoritics & Planetary Science* 44: 375-387. https://doi.org/10.1111/j.1945-5100.2009.tb00739.x.

Gorelick, N., Hancher, M., Dixon, M., Ilyushchenko, S., Thau, D., and Moore, R. 2017. Google Earth Engine: Planetary-Scale Geospatial Analysis for Everyone. *Remote Sensing of Environment* 202: 18-27.

Goudie, A. S., Wright, E., and Viles, H. A. 2002. The Roles of Salt (Sodium Nitrate) and Fog in Weathering: A Laboratory Simulation of Conditions in the Northern Atacama Desert, Chile. *Catena* 48: 255-266.

Greenwood, R. C., Franchi, I. A., Gibson, J. M., and Benedix, G. K. 2012. Oxygen Isotope Variation in Primitive Achondrites: The Influence of Primordial, Asteroidal and Terrestrial Processes. *Geochimica et Cosmochimica Acta* 94: 146-163. https://doi.org/10.1016/j.gca.2012.06.025.

Grosjean, M., Cartajena, I., Geyh, M. A., and Nuñez, L. 2003. From Proxy Data to Paleoclimate Interpretation: The Mid-Holocene Paradox of the Atacama Desert, Northern Chile. *Palaeogeography, Palaeoclimatology, Palaeoecology* 194: 247-258. https://doi.org/10.1016/S0031-0182(03)00280-3.

Hezel, D. C., Schlüter, J., Kallweit, H., Jull, A. J. T., al Fakeer, O. Y., al Shamsi, M., and Strekopytov, S. 2011. Meteorites from the United Arab Emirates: Description, Weathering, and Terrestrial Ages. *Meteoritics & Planetary Science* 46: 327-336. https://doi.org/10.1111/j.1945-5100.2010.01165.x.

Hofmann, B. A., Gnos, E., Jull, A. J. T., Szidat, S., Majoub, A., al Wagdani, K., Habibullah, S. N., et al. 2018. Meteorite Reconnaissance in Saudi Arabia. *Meteoritics & Planetary Science* 53: 2372-94. https://doi.org/10.1111/maps.13132.

Houston, J., and Hartley, A. J. 2003. The Central Andean West-Slope Rainshadow and its Potential Contribution to the Origin of Hyper-Aridity in the Atacama Desert. *International Journal of Climatology* 23: 1453-64. https://doi.org/10.1002/joc.938.

Hutson, M., Ruzicka, A., Timothy Jull, A. J., Smaller, J. E., and Brown, R. 2013. Stones from Mohave County, Arizona: Multiple Falls in the “Franconia Strewn Field”.
*Meteoritics & Planetary Science* 48: 365–389. https://doi.org/10.1111/maps.12062.

Hutzler, A., Gattacceca, J., Rochette, P., Braucher, R., Carro, B., Christensen, E. J., Cournede, C., et al. 2016. Description of a Very Dense Meteorite Collection Area in Western Atacama: Insight into the Long-Term Composition of the Meteorite Flux to Earth. *Meteoritics & Planetary Science* 51: 468–482. https://doi.org/10.1111/maps.12607.

Ikeda, Y., and Kojima, H. 1991. Terrestrial Alteration of Fe-Ni Metals in Antarctic Ordinary Chondrites and the Relationship to their Terrestrial Ages. *Antarctic Meteorite Research* 4: 307.

Ivanova, M. A., Lorenz, C. A., Humayun, M., Corrigan, C. M., Ludwig, T., Trieloff, M., Righter, K., et al. 2020. Sierra Gorda 009: A New Member of the Metal-Rich G Chondrites Grouplet. *Meteoritics & Planetary Science* 55: 13546. https://doi.org/10.1111/maps.13546.

Jull, A. J. T., Giscard, M. D., Hutzler, A., Schnitzer, C. J., Zahn, D., Burr, G. S., McHargue, L. R., and Hill, D. 2013. Radionuclide Studies of Stony Meteorites from Hot Deserts. *Radiocarbon* 55: 1779–89. https://doi.org/10.1017/s0033822200048682.

Killgore, B. M. 1997. Imilac Strewnfield, Chile, Revisited, 28th *Lunar and Planetary Science Conference*, 725.

Köppen, W. 1884. Die Wärmezonen der Erde, nach der Dauer der heissen, gemässigten und kalten Zeit und nach der Wirkung der Wärme auf die organische Welt betrachtet. *Meteorologische Zeitschrift* 1: 215–226.

Kouvatsis, I., and Hofmann, B. A. 2020. A Statistical Analysis of the H/L Ratio of Ordinary Chondrite Finds and Falls: A Comparison of Oman Finds with Other Populations. *Meteoritics & Planetary Science* 55: 67–76. https://doi.org/10.1111/maps.13410.

Krämer Ruggiu, L., Gattacceca, J., Devouard, B., Udry, A., Debaille, V., Rochette, P., Lorand, J. P., et al. 2020. Caleta el Cobre 022 Martian Meteorite: Increasing Nakhlite Diversity. *Meteoritics & Planetary Science* 55: 1539–63. https://doi.org/10.1111/maps.13534.

Kring, D. A., Jull, A. J. T., McHargue, L. R., Bland, P. A., Hill, D. H., and Berry, F. J. 2001. Gold Basin Meteorite Strewn Field, Mojave Desert, Northwestern Arizona: Relic of a Small Late Pleistocene Impact Event. *Meteoritics & Planetary Science* 36: 1057–66. https://doi.org/10.1111/j.1945-5100.2001.tb01944.x.

Krot A. N., Keil K., Goodrich C., Weisberg M. K., and Scott E. R. D. 2014. Classification of Meteorites. In *Meteorites, Comets and Planets*, edited by A. M Davis, Treatise on Geochemistry, vol. 1 (edited by H. D. Holland and K. K. Turekian), 1–63. Oxford: Elsevier.

Latorre, C., Betancourt, J. L., Rylander, K. A., Quade, J., and Matthei, O. 2003. A Vegetation History from the Arid Prepuna of Northern Chile (22–23°S) Over the Last 13 500 Years. *Palaeogeography, Palaeoclimatology, Palaeoecology* 194: 223–246. https://doi.org/10.1016/S0031-0182(03)00279-7.

Lee, M. R., and Bland, P. A. 2004. Mechanisms of Weathering of Meteorites Recovered from Hot and Cold Deserts and the Formation of Phyllosilicates. *Geochimica et Cosmochimica Acta* 68: 893–916. https://doi.org/10.1016/S0016-7037(03)00486-1.

Lee, N. N., Fritz, J., Fries, M. D., Gil, J. F., Beck, A., Pellinen-Wannberg, A., Schmitz, B., Steele, A., and Hofmann, B. A. 2017. The Extreme Biology of Meteorites: Their Role in Understanding the Origin and Distribution

of Life on Earth and in the Universe. In *Adaption of Microbial Life to Environmental Extremes*, edited by H. Stan-Lotter, and S. Fendrihan, 2nd ed., 283–325. Cham, Switzerland: Springer.

Losiak, A., and Velbel, M. A. 2011. Evaporite Formation during Weathering of Antarctic Meteorites—A Weathering Census Analysis Based on the ANSMET Database. *Meteoritics & Planetary Science* 46: 443–458. https://doi.org/10.1111/j.1945-5100.2010.01166.x.

Maeda, R., Goderis, S., Debaille, V., Pourkhorsandi, H., Hublet, G., and Claeys, P. 2021. The Effects of Antarctic Alteration and Sample Heterogeneity on Sm-Nd and Lu-Hf Systematics in H Chondrites. *Geochimica et Cosmochimica Acta* 305: 106–129.

Marinovic, N., Smoje, I., Maksaev, V., Herv, M., and Mpodozis, C. 1995. Hoja Aguas Blancas. Servicio Nacional de Geología y Minería, Carta Geológica de Chile No. 70, Región de Antofagasta, 150. Santiago.

Marquet, P., Bozinovic, F., Bradshaw, G. A., Cornelius, C., Gonzalez, H., Gutierrez, J. R., Hajek, E. R., et al. 1998. Los ecosistemas del Desierto de Atacama y área Andina adjacente. *Revista Chilena de Historia Natural* 71: 593–617.

Martínez, F., Muñoz, B., López, C., González, R., Parra, M., and Riquelme, R. 2021. Complex Basement-Involved Conformational Structures in the Pre-Andean Basins of Northern Chile: A Review from Seismic Data. *Tectonics* 40: 1–23. https://doi.org/10.1029/2020TC006433.

Metzler, K., Hezel, D. C., Barosch, J., Wölfer, E., Schneider, J. M., Hellmann, J. L., Berndt, J., et al. 2021. The Loongana (CL) Group of Carbonaceous Chondrites. *Geochimica et Cosmochimica Acta* 304: 1–31. https://doi.org/10.1016/j.gca.2021.04.007.

Munayco, P., Munayco, J., de Avillez, R. R., Valenzuela, M., Rochette, P., Gattacceca, J., and Scorzelli, R. B. 2013. Weathering of Ordinary Chondrites from the Atacama Desert, Chile, by Mössbauer Spectroscopy and Synchrotron Radiation X-Ray Diffraction. *Meteoritics & Planetary Science* 48: 457–473. https://doi.org/10.1111/maps.12067.

Muñoz, C., Guerra, N., Martínez-Frías, J., Lunar, R., and Cerda, J. 2007. The Atacama Desert: A Preferential Arid Region for the Recovery of Meteorites-Find Location Features and Strewnfield Distribution Patterns. *Journal of Arid Environments* 71: 188–200. https://doi.org/10.1016/j.jaridenv.2007.03.007.

Nishiizumi, K., Elmore, D., and Kubik, P. W. 1989. Update on Terrestrial Ages of Antarctic Meteorites. *Earth and Planetary Science Letters* 93: 299–313.

Ouazaa, N. L., Perchiazzi, N., Kassaa, S., Zeoli, A., Ghanmi, M., and Folco, L. 2009. Meteorite Finds from Southern Tunisia. *Meteoritics & Planetary Science* 44: 955–960. https://doi.org/10.1111/j.1945-5100.2009.tb00780.x.

Ouknine, L., Khiri, F., Ibhi, A., Heikal, M. T. S., Saint-Gerant, T., and Medjkane, M. 2019. Insight into African Meteorite Finds: Typology, Mass Distribution and Weathering Process. *Journal of African Earth Sciences* 158: 103551. https://doi.org/10.1016/j.jafrearsci.2019.103551.

Pastukhovich, A. Y., Larionov, M. Y., Kruglikov, N. A., Kolunin, R. N., Sharygin, V. V., and Grokhovsky, V. I. 2018. UrFU Meteorite Expedition to the Atacama Desert (Chile) 81st Annual Meeting of the Meteoritical Society, Moscow, Russia, abstract #2067.

Pedersen, H., Bon, C. C., and Lindgren, H. 1992. Vaca Muerta Mesosiderite Strewnfield. *Meteoritics* 27: 126–135. https://doi.org/10.1111/j.1945-5100.1992.tb00739.x.
Peltier, L. C. 1950. The Geographic Cycle in Periglacial Regions as it is Related to Climatic Geomorphology. *Annals of the Association of American Geographers* 40(3): 214-236. https://doi.org/10.1080/00045605009352070.

Peltier, L. C. 1973. The Geographic Cycle in Periglacial Regions as it is Related to Climatic Geomorphology. *Climatic Geomorphology*: 131-152. https://doi.org/10.1007/978-1-349-15508-8_9.

Pfeiffer, M., Morgan, A., Heimsath, A., Jordan, T., Howard, A., and Amundson, R. 2021. Century Scale Rainfall in the Absolute Atacama Desert: Landscape Response and Implications for Past and Future Rainfall. *Quaternary Science Reviews* 254: 106797. https://doi.org/10.1016/j.quascirev.2021.106797.

Pinto, G. A., Marrocchi, Y., Jacquet, E., and Olivares, F. 2022. Formation of Chondrule Fine-Grained Rims from Local Nebular Reservoirs. *Meteoritics & Planetary Science* 14: 1-14. https://doi.org/10.1111/maps.13812.

Placzek, C. J., Matmon, A., Granger, D. E., Quade, J., and Niedermann, S. 2010. Evidence for Active Landscape Evolution in the Hyperarid Atacama from Multiple Terrestrial Cosmogenic Nuclides. *Earth and Planetary Science Letters* 295: 12-20.

Pourkhorsandi, H., Gattacceca, J., Devouard, B., D'Orazio, M., Rochette, P., Beck, P., Sonzogni, C., and Valenzuela, M. 2017. The Ungrouped Chondrite El Médano 301 and its Comparison with Other Reduced Ordinary Chondrites. *Geochimica et Cosmochimica Acta* 218: 98-113. https://doi.org/10.1016/j.gca.2017.09.013.

Pourkhorsandi, H., Gattacceca, J., Rochette, P., D'Orazio, M., Kamali, H., de Avillez, R., Letichevsky, S., et al. 2019. Meteorites from the Lut Desert (Iran). *Meteoritics & Planetary Science* 54: 1737-63. https://doi.org/10.1111/maps.13311.

Pourkhorsandi, H., Gattacceca, J., Rochette, P., Smith, T., Bonal, L., D'Orazio, M., Devouard, B., Sonzogni, C., and Debaille, V. 2022. The Famenin Fall and Other Ordinary Chondrites Intermediate between H and L Groups. *Meteoritics & Planetary Science* 22: 1038-59. https://doi.org/10.1111/maps.13801.

Rech, J. A., Currie, B. S., Michalski, G., and Cowan, A. M. 2006. Neogene Climate Change and Uplift in the Atacama Desert, Chile. *Geology* 34: 761-64.

Rech, J. A., Quade, J., and Hart, W. S. 2003. Isotopic Evidence for the Source of Ca and S in Soil Gypsum, Anhydrite and Calcite in the Atacama Desert, Chile. *Geochimica et Cosmochimica Acta* 67: 575-586. https://doi.org/10.1016/S0016-7037(02)01175-4.

Rubin, A. E., Verish, R. S., Moore, C. B., and Oriti, R. A. 2000. Numerous Unpaired Meteorites Exposed on a Deflating Playa Lake at Lucerne Valley, California. *Meteoritics & Planetary Science* 35(S5): A181-A183. https://doi.org/10.1111/j.1945-5100.2000.tb01793.x.

Rundel, P. W., Dillon, M. O., Palma, B., Mooney, H. A., Gulmon, S. L., and Ehleringer, J. R. 1991. The

Phytogeography and Ecology of the Coastal Atacama and Peruvian Deserts. *Aliso* 13: 1-49. https://doi.org/10.5642/aliso.19911301.02.

Schlüter, J., Schultz, L., Thiedig, F., Al-Mahdi, B. O., and Aghreb, A. E. A. 2002. The Dar al Gani Meteorite Field (Libyan Sahara): Geological Setting, Pairing of Meteorites, and Recovery Density. *Meteoritics & Planetary Science* 37: 1079-93. https://doi.org/10.1111/j.1945-5100.2002.tb00879.x.

Stephant, A., Garvie, L. A. J., Mane, P., Hervig, R., and Wadhwa, M. 2018. Terrestrial Exposure of a Fresh Martian Meteorite Causes Rapid Changes in Hydrogen Isotopes and Water Concentrations. *Scientific Reports* 8: 6-12. https://doi.org/10.1038/s41598-018-30807-w.

Tait, A. W., Wilson, S. A., Tomkins, A. G., Gagen, E. J., Fallon, S. J., and Southam, G. 2017. Evaluation of Meteorites as Habitats for Terrestrial Microorganisms: Results from the Nullarbor Plain, Australia, a Mars Analogue Site. *Geochimica et Cosmochimica Acta* 215: 1-16. https://doi.org/10.1016/j.gca.2017.07.025.

Valenzuela, E. M. 2011. *Procesos de Meteorización en Condritos Ordinarios del Desierto de Atacama, Norte de Chile: Nuevos Antecedentes sobre Meteorización de Material Extraterrestre en Ambientes Deserticos*. PhD thesis. Santiago, Chile: Universidad de Chile.

Van Ginneken, M., Debaille, V., Decrée, S., Goderis, S., Woodland, A. B., Wozniakiewicz, P., De Ceukelaire, M., Leduc, T., and Claeys, P. 2022. Artificial Weathering of an Ordinary Chondrite: Recommendations for the Curation of Antarctic Meteorites. *Meteoritics & Planetary Science* 57: 1247-66. https://doi.org/10.1111/maps.13818.

Wasson, J. T., and De Bon, C. C. 1998. New Chilean Iron Meteorites: Medium Octahedrites from Northern Chile are Unique. *Meteoritics & Planetary Science* 33: 175-79.

Whillans, I. M., and Cassidy, W. A. 1983. Catch a Falling Star: Meteorites and Old Ice. *Science* 222(4619): 55-57. https://doi.org/10.1126/science.222.4619.55.

Wlotzka, F. 1993. A Weathering Scale for the Ordinary Chondrites. *Meteoritics* 28: 460.

Zeng, X., Li, S., Leya, I., Wang, S., Smith, T., Li, Y., and Wang, P. 2018. The Kumtag 016 L5 Strewn Field, Xinjiang Province, China. *Meteoritics & Planetary Science* 53: 1113-30. https://doi.org/10.1111/maps.13073.

Zolensky, M. E., Wells, G. L., and Rendell, H. M. 1990. The Accumulation Rate of Meteorite Falls at the Earth's Surface: The View from Roosevelt County, New Mexico. *Meteoritics* 25: 11-17. https://doi.org/10.1111/j.1945-5100.1990.tb00965.x.

Zurfluh, F. J., Hofmann, B. A., Gnos, E., Eggenberger, U., and Jull, A. J. T. 2016. Weathering of Ordinary Chondrites from Oman: Correlation of Weathering Parameters with 14C Terrestrial Ages and a Refined Weathering Scale. *Meteoritics & Planetary Science* 51(9): 1685-1700. https://doi.org/10.1111/maps.12690.

## SUPPORTING INFORMATION

Additional supporting information may be found in the online version of this article.

**TABLE S1.** The area of 13 selected Atacama DCAs defined in MetBull and estimated according to only the pixels (4.6 km²) located in the surfaces where meteorites were found (called productive areas).