Caroline Sanchez

Vincent Regard
email: vincent.regard@get.omp.eu

Sebastien Carretier

Rodrigo Riquelme Salazar

Pierre-Henri Blard

Eduardo Campos

Stéphanie Brichaud

Maarten Lupker

Gerard Herail

Riquelme Salazar

Sébastien Carretier

Rodrigo Riquelme

Stéphanie Brichau

Gérard Hérail

Neogene basin infilling from cosmogenic nuclides (10Be and 21Ne) in Atacama, Chile: implications for paleoclimate and copper supergene enrichment

Keywords: supergene copper deposits, Economic Geology, cosmogenic nuclides, Atacama, denudation rates, intramountainous basin, sediment flux, burial dating supergene copper deposits, Atacama, cosmogenic nuclides, denudation rates, burial dating, intramountainous basin

scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

The Atacama Desert in northern Chile and southernmost Peru hosts the biggest concentration of world-class porphyry copper deposits on Earth [START_REF] Sillitoe | Porphyry copper systems[END_REF]. Nearly all of these deposits show features related to supergene processes that produce an increase in hypogene copper grades on top of porphyry copper systems through reduction-oxidation reactions occurring during weathering phases (e.g., [START_REF] Sillitoe | Porphyry copper systems[END_REF]. The leached copper can reprecipitate above the water table as oxidized minerals such as Chrysocolla and Atacamite or it can also be concentrated below the paleowater table as secondary sulfides (e.g. chalcocite, covelite). Fluids containing leached copper may eventually migrate laterally and transport copper up to several kilometers away from the weathered source of metal, until the copper precipitates form exotic (away from the metal source) copper deposits (e.g., [START_REF] Münchmeyer | Exotic deposits-products of lateral migration of supergene solutions from porphyry copper deposits[END_REF]. Although the precise balance between precipitation, uplift and denudation rate for the generation of these deposits has not been quantified yet, the formation of oxidized minerals supergene (i.e., mineralized close to the Earth's surface) is usually considered to have occurred during pulses of humidity in a context of an arid climate during the Neogene in the Atacama (e.g., [START_REF] Arancibia | K-Ar and 40Ar/39Ar geochronology of supergene processes in the Atacama Desert, Northern Chile: Tectonic and climatic relations[END_REF][START_REF] Reich | Supergene enrichment of copper deposits since the onset of modern hyperaridity in the Atacama Desert, Chile[END_REF]Palacios et al., 2011b;Reich and Vasconcelos, 2015b;Fernández-Mort et al., 2017b;Riquelme et al., 2018;Sanchez et al., 2018). Thus, the precipitation of oxidized minerals is not only of particular interest to trace exploitable deposits, but also to reconstruct past climates. Even though multi-approach studies tend to agree with the long-term aridity of the Atacama Desert, the timing of the hyperaridity onset is still matter of debate (see Figure 1 for a review and references). Nevertheless, the effect of rainfall is ambiguous. An increase in rainfall favors lixiviation and the lateral transport of fluids from which oxidized minerals will precipitate. Meanwhile, higher surface runoff favors erosion and thus removes the oxidized layer. Consequently, denudation of the porphyry copper system is a key process to understanding the formation of supergene copper deposits (Alpers and Brimhall 1988;[START_REF] Braxton | Ultra-Deep Oxidation and Exotic Copper Formation at the Late Pliocene Boyongan and Bayugo Porphyry Copper-Gold Deposits, Surigao, Philippines: Geology, Mineralogy, Paleoaltimetry, and their Implications for Geologic, Physiographic, and Tectonic Controls[END_REF]. In this contribution, we show how the denudation rates of the source area may impact the formation of exotic copper. In the Centinela Mining District (Antofagasta region, Chile, Figure 2), recent sedimentological and thermochronological studies have demonstrated that supergene copper mineralization related to porphyry copper systems formed during pedimentation periods in the Miocene, corresponding to the waning of the Domeyko range with mean denudation rates in the order of 100 m/Ma (Riquelme et al. 2018;Sanchez et al. 2018). In this district, [START_REF] Fernández-Mort | A genetic model based on evapoconcentration for sediment-hosted exotic-Cu mineralization in arid environments: The case of the El Tesoro Central copper deposit, Atacama Desert, Chile[END_REF] evidenced the role of results, we also discuss the age and the sedimentary response to the Late Miocene aridification of the Atacama region.

2 Geological background and sampling

Geological background

The Centinela Mining District is located at approximately 23°S, in the Precordillera physiographic unit of the Andean forearc (see location in Figure 1). It is bordered by the Central Depression to the west and by the Atacama Salar to the east. In the district, several copper mines are currently exploited: the Tesoro Central, Tesoro NE, Esperanza, Telegrafo, Mirador and Encuentro with few exploration projects still under development [START_REF] Tomlinson | Structural evolution and displacement history of the West Fault System, Precordillera, Chile: Part 2, postmineral history[END_REF][START_REF] Mpodozis | Cenozoic Tectonics and Porphyry Copper Systems of the Chilean Andes[END_REF].

In the Precordillera, the Paleozoic-Triassic basement and the sedimentary cover (Jurassic marine to Upper Cretaceous continental volcano-sedimentary rocks) host intrusives, related to the Late Cretaceous to Eocene magmatic arc (Marinovic and García 1999;[START_REF] Mpodozis | Cenozoic Tectonics and Porphyry Copper Systems of the Chilean Andes[END_REF]. These rocks have been faulted during the Eocene tectonic phase by the Domeyko Fault System [START_REF] Only Basin Research | Estudio Geológico-Estructural de la Cordillera de Domeyko entre Sierra Limón Verde y Sierra Mariposas, Región de Antofagasta[END_REF][START_REF] Amilibia | The role of inherited tectono-sedimentary architecture in the development of the central Andean mountain belt: Insights from the Cordillera de Domeyko[END_REF][START_REF] Mpodozis | Cenozoic Tectonics and Porphyry Copper Systems of the Chilean Andes[END_REF]. At the regional scale, the activity of the fault system resulted in the creation of intra-mountainous basins such as the Centinela Basin [START_REF] Mora | El Tesoro exotic copper deposit, Antofagasta region, northern Chile[END_REF]Riquelme et al. 2018). This tectonic episode was synchronous to the emplacement of the Eocene metallogenic belt. In the Centinela Basin, porphyry copper systems were emplaced synchronously to the movement of faults related to the Domeyko Fault System, such as the Tesoro Central, Tesoro NE, Llano, Centinela, and Esperanza faults (see Figure 2). Late (< 10 Ma) fault activity has resulted in the uplift of the western block where the central Tesoro mining pit is located, with respect to the eastern block where the Mirador mining pit is located [START_REF] Mpodozis | Cenozoic Tectonics and Porphyry Copper Systems of the Chilean Andes[END_REF]. Supergene copper mineralization over substratum rocks and exotic copper mineralization hosted by gravel deposits can be found in the Centinela Basin [START_REF] Fernández-Mort | A genetic model based on evapoconcentration for sediment-hosted exotic-Cu mineralization in arid environments: The case of the El Tesoro Central copper deposit, Atacama Desert, Chile[END_REF]. The age of the exotic copper mineralization is unclear due to the lack of datable material within the mineralized sequence. Detailed sedimentary studies have identified four main gravel groups [START_REF] Mora | El Tesoro exotic copper deposit, Antofagasta region, northern Chile[END_REF]Riquelme et al. 2018). The Esperanza and Atravesado gravels are younger than ~45 Ma and ~40 Ma respectively (constrained by detrital zircon ages within the sedimentary sequence, Riquelme et al. 2018). The topmost sequence consists of the Tesoro and Arrieros gravels (Figure 2), in which a 9.5 Maold ash layer is intercalated (De Silva, 1989, (Riquelme et al., 2018). In the Atacama Desert, several types of supergene minerals have been dated by 40 Ar/ 39 Ar and K/Ar and recently, for the first time, chrysocolla minerals were also dated from the Chuquicamata mine using U-Pb; all together, these minerals yield ages mostly ranging from 25 to 9 Ma as well as a few ages as young as the Pleistocene [START_REF] Arancibia | K-Ar and 40Ar/39Ar geochronology of supergene processes in the Atacama Desert, Northern Chile: Tectonic and climatic relations[END_REF]. A similar age range (25-12 Ma) has been found in the Centinela District using 40 Ar/ 39 Ar and K/Ar methods on supergene minerals [START_REF] Sillitoe | Age of Supergene oxidation and enrichment in the chilean porphyry copper province[END_REF]Perelló 2010;[START_REF] Tapia | Estratigrafía y sedimentología de la Cuenca El Tesoro, Distrito Centinela (región de Antofagasta) y su relación con la mineralización exótica de cobre. XIII Congreso Geológico Chile[END_REF]Riquelme et al. 2018). In the Tesoro NE mine (eastern pit), a single exotic supergene mineral age obtained in a copper-rich layer was estimated at ~21 Ma. It has been proposed that the layer bearing this age is a stratigraphic equivalent of the exotic copper layer observed in the Teroso Central mining pit [START_REF] Tapia | Estratigrafía y sedimentología de la Cuenca El Tesoro, Distrito Centinela (región de Antofagasta) y su relación con la mineralización exótica de cobre. XIII Congreso Geológico Chile[END_REF]; see location in Figure 2 and Figure 4). These two mining pits (Tesoro Central and Tesoro NE pits) are structurally separated by the Tesoro Fault (see Error! Reference source not found. et al., 2018).

Geomorphic background: denudation rates and paleoclimate

Long-term denudation rates in the Centinela District have been determined by lowtemperature thermochronology on Paleocene intrusives and Eocene porphyry copper deposits (Sanchez et al. 2018). These data suggest that most of the exhumation had occurred before 30 Ma, and that the denudation rates have dropped drastically since then [START_REF] Maksaev | Fission track thermochronology of the Domeyko Cordillera, northern Chile; implications for Andean tectonics and porphyry copper metallogenesis[END_REF]Sanchez et al. 2018). The supergene mineral ages in the area are younger than the main exhumation phase [START_REF] Arancibia | K-Ar and 40Ar/39Ar geochronology of supergene processes in the Atacama Desert, Northern Chile: Tectonic and climatic relations[END_REF]Sanchez et al., 2018) confirming that supergene copper mineralization occurs in flat landscapes characterized by low relief and low denudation rates [START_REF] Mortimer | The Cenozoic history of the southern Atacama Desert, Chile[END_REF]Alpers and Brimhall 1988;[START_REF] Clark | Geomorphologic environment and age of supergene enrichment of the Cuajone, Quellaveco, and Toquepala porphyry copper deposits, southeastern Peru[END_REF][START_REF] Mote | Chronology of Exotic Mineralization at El Salvador, Chile, by 40Ar/39Ar Dating of Copper Wad and Supergene Alunite[END_REF][START_REF] Quang | Response of Supergene Processes to Episodic Cenozoic Uplift, Pediment Erosion, and Ignimbrite Eruption in the Porphyry Copper Province of Southern Perú[END_REF]Sanchez et al. 2018).

Several studies have estimated erosion (denudation) rates at the regional scale. In the Atacama Desert in northern Chile (18-30°S), for example, the current denudation rates measured by river sediment loads range from 0.1 to 10 m/Ma with a notable exception on the Lluta River (~43 m/Ma, [START_REF] Carretier | Review of erosion dynamics along the major N-S climatic gradient in Chile and perspectives[END_REF]. At the millennium scale range, cosmogenic nuclides record catchment-scale denudation rates up to ~60 m/Ma (Kober et al. 2009;[START_REF] Cortés-Aranda | Paleoseismology of the Mejillones Fault, northern Chile: Insights from cosmogenic 10Be and optically stimulated luminescence determinations[END_REF][START_REF] Carretier | Slope and climate variability control of erosion in the Andes of central Chile[END_REF]; see Figure 3).

At a local outcrop scale, cosmogenic nuclides have recorded maximum denudation rates values in the range 0.01-50 m/Ma, with a median value lower than 1 m/Ma (Dunai, Lopez, and Juez-Larre 2005;[START_REF] Nishiizumi | Remnants of a fossil alluvial fan landscape of Miocene age in the Atacama Desert of northern Chile using cosmogenic nuclide exposure age dating[END_REF]Kober et al. 2007;[START_REF] Evenstar | Multiphase development of the Atacama Planation Surface recorded by cosmogenic 3He exposure ages: Implications for uplift and Cenozoic climate change in Western South America[END_REF][START_REF] Gattacceca | The densest meteorite collection area in hot deserts: The San Juan meteorite field (Atacama Desert, Chile)[END_REF][START_REF] Cortés-Aranda | Paleoseismology of the Mejillones Fault, northern Chile: Insights from cosmogenic 10Be and optically stimulated luminescence determinations[END_REF][START_REF] Owen | The sensitivity of hillslope bedrock erosion to precipitation[END_REF][START_REF] Placzek | Geomorphic process rates in the central Atacama Desert, Chile: Insights from cosmogenic nuclides and implications for the onset of hyperaridity[END_REF][START_REF] Martinod | Pleistocene uplift, climate and morphological segmentation of the Northern Chile coasts (24°S-32°S): Insights from cosmogenic 10Be dating of paleoshorelines[END_REF]Ritter, Stuart, et al. 2018;Amundson et al. 2012). The currently observed low denudation rates may have lasted for millions of years, without significant change in elevation [START_REF] Blard | Paired-cosmogenic nuclide paleoaltimetry[END_REF]. Gypsisoil development may provide evidence of ~10 Ma of hyper-aridity and landform stability (rainfall < 40 mm/yr, [START_REF] Rech | Neogene climate change and uplift in the Atacama Desert, Chile[END_REF]): this geomorphological stability is further confirmed by the regional observation of the Artola ignimbrite dated at ~9.52 ± 0.02 Ma covering most of the landscape surface, affected by minor reworking after deposition (Riquelme et al. 2018).

On the contrary, there are few records of the paleo-denudation rate. Based on the cosmogenic 10 Be data, from north of our studied area, [START_REF] Madella | 10Be-inferred paleo-denudation rates imply that the mid-Miocene western central Andes eroded as slowly as today[END_REF] determined paleo-denudation rates ranging from 0.5 to 15 m/Ma for the period 10.3-12.8 Ma ago. On the basis of estimations of porphyry copper weathering rates, [START_REF] Arancibia | K-Ar and 40Ar/39Ar geochronology of supergene processes in the Atacama Desert, Northern Chile: Tectonic and climatic relations[END_REF] estimated that the denudation was less than 16-35 m/Ma from the Oligocene to Late Miocene. Finally, Alpers and Brimhall (1988) determined that erosion rates on the order of 100m/Ma enabled the exhumation of the La Escondida porphyry copper sometime between 33.7 and 18 Ma. These authors postulate that erosion dramatically decreased to less than 10m/Ma after ~15 Ma due to the onset of hyperaridity.

Sampling

A total of 14 samples were collected in the Centinela District, distributed in two different mine pits (nine samples from the Tesoro Central pit and five from the Mirador pit, see the location in Figure 4).

These two mines present different types of secondary copper mineralization. In the Mirador mine, the porphyry copper and related supergene mineralization is visible at the bottom of the pit. In the case of the Tesoro Central mine, the copper mineralization is within a gravel sedimentary sequence and corresponds to an exotic type copper deposit (described in Fernandez-Mort et al., 2017) (see Figure 4 and Figure 5). In the Tesoro Central pit, samples were collected at depths between 65 and 135 meters, with a denser sampling around the copper-rich exotic layer (see details in Figure 4 and Figure 5). In the Mirador pit, sampling was performed between 10 and 65 meters deep (see Figure 4 and Figure 5), above and below the 9.5 Ma-old Artola ignimbrite. On each sampling point, nearly 500 g of fine-to-coarse sediment was collected.

Methods based on cosmogenic nuclides

Basic systematics

In-situ cosmogenic nuclides are produced within the Earth's surface material through nuclear reactions (mostly spallation but also muonic capture) caused by cosmic rays. Spallation processes occur within a couple of meters below the Earth's surface (e.g., [START_REF] Lal | Cosmic ray labeling of erosion surfaces: In-situ nuclide production rates and erosion models[END_REF][START_REF] Gosse | Terrestrial in situ cosmogenic nuclides: Theory and application[END_REF]. The concentration of in situ-produced nuclides (i.e., produced within the crystal lattice) reflects the time the mineral spent in the production zone (c.a. from the surface to a few meters below thesurface). This is controlled by the date of exposure initiation, the local denudation rate and the local production rate (e.g., [START_REF] Bierman | Estimating Rates of Denudation Using Cosmogenic Isotope Abundances in Sediment[END_REF][START_REF] Brown | Denudation rates determined from the accumulation of in situ-produced 10Be in the luquillo experimental forest, puerto rico[END_REF]. Moreover, it has been shown that due to fluvial processes, it is possible to determine that the concentrations of cosmogenic nuclides in detrital sediments have reached steady-state and can be used to determine the catchment-wide spatial average denudation rate [START_REF] Brown | Denudation rates determined from the accumulation of in situ-produced 10Be in the luquillo experimental forest, puerto rico[END_REF][START_REF] Granger | Spatially Averaged Long-Term Erosion Rates Measured from in Situ-Produced Cosmogenic Nuclides in Alluvial Sediment[END_REF]. In addition, as some of the cosmogenic nuclides are radioactive (e.g. 26 Al, 10 Be), a decay term must be considered, but it does not depend on the surface processes. Apart from the 'simple exposure' scenario resolved by a single nuclide, two cosmogenic nuclides can be analyzed together to calculate the rock burial duration after having been exposed to cosmic rays at the Earth's surface (Granger and Muzikar, 2001). This technique relies on the fact that two cosmogenic nuclides are similarly produced at the Earth's surface, when the production ratio is known. When the host minerals are buried, their concentration in the various cosmogenic nuclides decay differently, therefore the ratio between them evolves. This is most often achieved using the 26 Al/ 10 Be pair of cosmogenic nuclides (Balco and Shuster 2009). The burial time t b is given by Equation 1, where N A and N B are nuclide concentrations at time t, P A and P B are the respective production rates, λ A and λ B are the respective decay constants (value of 0 for stable nuclides) and f is the scaling factor at the exposure location [START_REF] Blard | Paired-cosmogenic nuclide paleoaltimetry[END_REF].

(equation 1)

𝑃 𝐴 𝑁 𝐴 𝑒 -𝜆 𝐴 𝑡 𝑏 - 𝑃 𝐵 𝑁 𝐵 𝑒 -𝜆 𝐵 𝑡 𝑏 = 𝜆 𝐴 -𝜆 𝐵
𝑓 For a detrital basin such as the one studied here, the single clast cosmogenic nuclide concentration reflects a two-step-history (Figure 6). First, the pre-burial (initial) ratio of the paired nuclides (R AB (0)) depends on the production rates and on the duration of the sediment residence in the source. R AB (0) is acquired either during steady-state denudation rates (ε in Figure 6) or following a more complex exposure history in the uplands with successive temporary storage along hillslopes and along the river system [START_REF] Lal | Cosmic ray labeling of erosion surfaces: In-situ nuclide production rates and erosion models[END_REF]Balco and Shuster 2009). Although transport durations of several tens of thousands years have been recently evidenced for large pebbles in a modern Atacama river (Carretier et al., 2019), the subsequent transport duration from the catchment to the sedimentary basin is generally not long enough for a significant concentration to build up. This pre-burial step, usually called "inheritance", is fundamental as it produces the cosmogenic nuclide content of newly-deposited sediments, which are used to decipher the history. In the case where some of the sediments underwent various cycles of exposure and burial, stable 21 Ne record the pre-burial history in a more dramatic manner than radioactive 10 Be. The homogeneity of the results discussed in the following makes the possibility of a complex pre-exposure improbable, except for two samples with high 21 Ne/ 10 Be ratios (e.g., samples ET-04 and MIR-11, Table 4). Finally, deposition within the sedimentary basin (at a rate Sr, Figure 6) leads to the second step of cosmogenic nuclide build-up, and this latter step is more important for low sedimentation rates. In the definition of t b , it is assumed that the amount of cosmogenic nuclides produced during this step is negligible. This assumption may be wrong during the Centinela Basin infilling: in this case, t b instead corresponds to a minimal estimation for the deposition time.

In situ cosmogenic 10 Be and 21 Ne sample processing and measurements

Samples were prepared using the standard procedures (see supplementary information). Once pure quartz was obtained, the samples were split in two aliquots. The first one was used for 10 Be analysis, at GET and ASTER (except MIR-10, see Error! Reference source not found.).

The second quartz aliquot was used to measure the cosmogenic 21 Ne concentration at the CRPG Nancy noble gas lab (Table 3). During sample preparation, the grain morphology was checked. Some particular grain shapes were observed. For instance, quartz minerals present bipyramidal shapes (Figure 7) in sample MIR13-01, just above the 9.5 Ma-old ignimbrite (De Silva 1989;Riquelme et al. 2018). This crystal automorph shape suggests that it has a volcanic origin and was not transported over a long distance. MIR13-01 quartz minerals are likely to come from upstream erosion of the 9.5 Ma-old ignimbrite.

Simple burial

Following the systematics of cosmogenic nuclides, it is possible to derive a simple burial duration knowing the present-day concentrations of two nuclides with different radioactive half-lives as well as the scaling factor f (Equation 1). In practice, both the pre-burial exposure duration (or denudation rate) and the local production rate determines the pre-burial nuclides ratio, R AB (0) [START_REF] Blard | Paired-cosmogenic nuclide paleoaltimetry[END_REF]. However, when it is buried at low depth (< 10 m) or shielded by a slow sedimentation rate (< 10 m/Ma), the material is still exposed to cosmic rays. Hence, this results in an apparent burial duration (t b ) shorter than its real value. Burial durations computed with Equation 1 without any post deposition correction thus yield an end-member that is a minimum deposition time (t b ).

Inversion

We developed an R (R Core Team 2014) inversion program, called IMIS (available at https://github.com/regard-vincent/IMIS). It is based on a Monte Carlo approach, taking into account the evolution of the cosmogenic nuclide concentrations in a two-step clast history (Figure 6). The first step corresponds to the catchment denudation (box 1, Figure 6), neglecting the duration of the fluvial sediment transport to the basins. The catchment elevation is set to the current elevation of the basin. This choice is motivated by the following reasons: (1) there is evidence that the ancient total catchment relief was low (no more than several hundreds of meters; (2) the elevation of the basin may have changed, which means that our results are still valid, as mentioned in the discussion; and (3) further sensitivity tests indicate this is not critical for our analysis. The catchment denudation rate is allowed to vary in the code but is fixed in the inversions as presented in the following. This step allows to estimate the nuclide concentration from Equation 2 where P is the surface production, λ is the decay constant, ε is the denudation rate, ρ is the density and Λ is the attenuation coefficient; i denotes the various production pathways, usually spallation, and fast and stopped (negative) muons (see [START_REF] Brown | Denudation rates determined from the accumulation of in situ-produced 10Be in the luquillo experimental forest, puerto rico[END_REF][START_REF] Granger | Spatially Averaged Long-Term Erosion Rates Measured from in Situ-Produced Cosmogenic Nuclides in Alluvial Sediment[END_REF]Heisinger et al. 2002a;Heisinger et al. 2002b;[START_REF] Dunai | Cosmogenic Nuclides: Principles, concepts and applications in the Earth surface sciences[END_REF]Braucher et al. 2011). P depends on the elevation of the source rock; the sensitivity tests showed that, in this context, potential changes in elevation did not significantly impact the results presented hereafter.

(Equation 2)

𝐶 = ∑ 𝑖 𝑃 𝑖 𝜆 + 𝜌𝜀 Λ 𝑖
The second step corresponds to the sedimentation in the basin (box 2, Figure 6). In our model, the basin infill is divided into periods, each being bounded by well-defined events such as the current surface, or in our case, the emplacement of the Artola ~9.5 Ma-old ignimbrite layer. A period is divided into various sub-periods with a random duration and a random sedimentation rate; the duration and thicknesses follow uniform laws whereas the sedimentation rate corresponds to the ratio between thickness and duration. The number of sub-periods is fixed to seven, typically. The total sedimentation during a period is adjusted (by a multiplication ratio) to satisfy its stratigraphic thickness. The basement rock and sediment densities are set to 2700 kg/m 3 and 2300 kg/m 3 , respectively. Once a scenario has been drawn with its succession of sub-periods with specified sedimentation rates and durations, the model time is subsampled into time steps of 5 ka to compute the 10 Be and 21 Ne concentrations, as described in the following. During each time step, we compute the concentrations of 10 Be and 21 Ne in two steps, first in box 1 and then in box 2. In box 1, the 10 Be and 21 Ne concentrations are calculated depending on their respective production rates at the elevation of the catchment, and the average catchment denudation (Equation 2). These concentrations are attributed to the newly deposited surface layer in the basin in box 2. At each time step, the 10 Be and 21 Ne concentrations in all of the deeper layers in the basin are updated taking both the decay of 10 Be and the undersurface production of 10 Be and 21 Ne over the last 5 ka (duration of one-time step) into account. This production strongly depends on the production scheme. The production at depth is often modelled with an exponential attenuation (although not for model HS, see below):

. (Equation 3) 𝑃 𝑖 (𝑧) = 𝑃 𝑖 (𝑧 = 0).𝑒 Since there are different models describing the attenuation of 10 Be and 21 Ne production at depth that we explore in this study; we detail these models below. In the eroding areas (box 1), we only use one exponential attenuation scheme, while we use several schemes in the sedimentation area, called GH, BH, HS, BR (See Error! Reference source not found. and Figure 8 for more details). The first letter stands for the 10 Be production scheme: G for Granger and Muzikar (2001), B for Braucher et al. (2011), H for [START_REF] Heisinger | Production of selected cosmogenic radionuclides by muons: 2. Capture of negative muons[END_REF]. The second letter is indicative of the 21 Ne production scheme: H and S for [START_REF] Heisinger | Production of selected cosmogenic radionuclides by muons: 2. Capture of negative muons[END_REF] and R for Braucher et al. (2011); 10 Be production SLHL is set to 4.15 at/g/a (Martin et al., 2017), and the 21 Ne/ 10 Be ratio is 4.12 (Balco and Shuster 2009a;[START_REF] Kober | The cosmogenic 21Ne production rate in quartz evaluated on a large set of existing 21Ne-10Be data[END_REF]. As we will see, the production parameter choice has a strong influence on the modeled concentration and subsequently on the misfit between the measured concentrations and their modeled values.

Once the 10 Be and 21 Ne concentrations have been updated, new 10 Be and 21 Ne concentrations are computed for box 1, which themselves are assigned to a new surface layer of box 2 and so on for the different time steps until the total duration of the modeled period is reached. This endpoint is reached when the basin is filled. The procedure described above constitutes a forward model that is run 5,000 times for different denudation and sedimentation scenarios in a Monte Carlo simulation. The best model parameters are then selected by minimizing the χ 2 misfit metric between the predicted and measured 10 Be and 21 Ne concentrations, defined by Equation 2. (Equation 4)

𝜒 2 = ∑ 𝑖 ( 𝐶 𝑜𝑏𝑠,𝑖 -𝐶 𝑚𝑜𝑑,𝑖 𝐸𝑟𝑟 𝑖 ) 2
where C obs,i , C mod,i and E rri are, respectively the observed concentration, the modelled concentration and associated analytical uncertainty for the sample n# i. For each Monte Carlo set of inversions, we calculated three minimum χ 2 values, one for each single nuclide (the concentrations in Equation 2 are only 10 Be or 21 Ne ones) and one considering together the misfit for the two nuclides (χ 2 calculated on the entire set of 10 Be and 21 Ne data). In order to validate our inversion model, IMIS, we tested it on Davis et al.'s dataset (2014) from the Atacama Desert gravels near our study zone. It provides similar results to the inversions processed by Davis et al. (2014); see supplementary material.

Results

Concentrations

Concentrations (Tables 2 and3) are comprised between (6  4 ) x 10 6 and (1.38  0.09) x 10 8 at/g for 21 Ne (plus three samples that are below the detection limit) and are measurable for 10 Be ( from (1.8  0.3) x 10 3 at/g to (9.70  0.32) x 10 5 at/g), indicating that the minimum burial duration must be less than ~18 Ma (in the case where the initial concentration is high, as in the present case), the time corresponding to the minimum detectable 10 Be concentration (Table 2 andTable 3).

Burial ages

Assuming that these samples underwent a single and instantaneous burial episode, these data indicate a burial duration (i.e. minimum deposition time) ranging from 6 to 18 Ma (Error! Reference source not found.). In the Tesoro Central pit, the obtained burial ages are relatively homogeneous along the stratigraphic column, around 11 Ma. These burial ages slightly increase from ~11 (~59 m-deep) to ~13 Ma 111 m below the surface (cf. Error! Reference source not found.). The samples located near the enriched copper layer display ages between 11 and 13 Ma. In the Mirador pit, the burial times reflect the stratigraphic order from ~7 Ma for the top samples, to ~14 Ma at a depth of 45 m below the surface. We decided to discard ET-04, because it is hard to reconcile it with the other data, as the burial duration of this sample is at odds with the stratigraphic order. This material probably underwent several exposure-burial cycles. Moreover, taking ET-04 into account increases the minimum χ 2 by one order of magnitude. Our reference inversion (production parameter BR, denudation rate = 5.10 -4 m/a, Page 15 of FOR REVIEW PURPOSES ONLY Basin Research discussed below) gives two important clues. First, the deposition of the copper-rich layer is likely 10-14 Ma old (Figure 9), and is followed by a stage of rapid sedimentation (~10 -4 m/a, cf. appendix). In fact, our misfit metric χ 2 is not very sensitive to input parameters, because the uncertainties are high compared to the measured concentrations (10-30% for 10 Be, Error! Reference source not found., 6-70% for 21 Ne, Table 3). Our interpretations are thus robust and have limited dependency on the production scheme used (see appendix). In the Mirador mining pit, the burial times reflect the stratigraphic order, from ~7 Ma for the top samples to ~14 Ma at a depth of 45 m below the surface. The upper ~7 Ma samples stand just above the 9.5 Ma-old Ar/Ar dated Artola ignimbrite, while the ~14 Ma deep samples are located dozens of meters below this (Figure 5). This observation indicates that the 21 Ne/ 10 Be burial durations (despite being minimal, not taking the production during deposition into account) are in agreement with the stratigraphic order (Error! Reference source not found.). Data from the Mirador pit better constrain sedimentation rate than the burial times, because the sedimentation rate is more efficient at varying the concentrations than radioactive decay.

Paleo-denudation and sedimentation rates, determined by forward modelling

The initial 21 Ne concentration in the sediments is the sum of 21 Ne acquired before the deposition, mostly during the material exhumation by denudation on hillslopes and 21 Ne produced during sedimentation. In the particular case of similar sedimentation and denudation rates, occurring at a similar elevation, half of the 21 Ne concentration comes from exposure on eroding hillslopes and half from sedimentation. In this case, Equation 2 can be inverted to obtain an integrated sedimentation and denudation rate. This sedimentation/denudation rate should therefore be interpreted as a minimum estimate for both denudation and sedimentation. For Mirador, this minimum is in the range 0.9-12 m/Ma, a value that can be regarded as similar to modern values (cf. [START_REF] Martinod | Pleistocene uplift, climate and morphological segmentation of the Northern Chile coasts (24°S-32°S): Insights from cosmogenic 10Be dating of paleoshorelines[END_REF][START_REF] Carretier | Review of erosion dynamics along the major N-S climatic gradient in Chile and perspectives[END_REF]. For Tesoro Central, this minimum is higher, except for ET-04 and lies around 20 m/Ma. The apparent disagreement likely comes from the fact that the samples are from different stratigraphic layers with different ages and therefore corresponding to different periods in the basin infilling history. Various forward calculations were performed, with different source area denudation rates. First, for The Tesoro Central pit, the denudation rate is set to a low value for the last 10 Ma (its value has little implication for the inversion), and to a higher value for the older stages. A denudation rate of 500 m/Ma is used for reference; as seen in the following, a high denudation rate is needed to explain the low cosmogenic nuclide concentrations observed in the sedimentary column. Inversions can hardly produce low cosmogenic nuclide concentrations, irrespective of the muonic production scheme. The surface position did not vary much for the last 10 Ma, leaving time for significant production at depth. Hence, low concentrations cannot be easily modeled (modeled concentrations are most often too high compared to the observed data, Figure 10). Furthermore, we found that the inversions for the Tesoro Central pit cannot reach satisfactory values for source denudation rates lower than 250 m/Ma for the pre-9.5 Ma period (see Figure 11 and Table 5). For the post-10 Ma period, we performed a forward model on the Mirador dataset, with different post-10 Ma denudation rates. For these latest stages, the results are affected by a lower uncertainty since the sampling of the Mirador site is denser. Best fits (low χ 2 ) yield relatively high denudation rates, higher than 50 m/Ma for the period 7-9.5 Ma (Figure 12. Figure 12).

Additional constraints on the copper-rich layer (Tesoro Central)

Our 10 Be/ 21 Ne data constrain the deposition age of the copper-rich layer in the Tesoro Central mining pit between 14 and 10 Ma. Moreover, the 10 Be concentration clearly increases towards the surface (Figure 10.A) as does 21 Ne (due to larger analytical uncertainties, this tendency is however questionable for 21 Ne, Figure 10.B). This suggests either a slow sedimentation rate during the deposition of the copper-bearing layer or a hiatus just after its deposition: the 10 Be best fits usually imply a sedimentation rate of the order of 0.5-5 m/Ma. This observation is confirmed by inversions for 10 Be, where the modelled concentrations exhibit a peak of concentration near the top of the copper-bearing layer (Figure 10), with minimum sedimentation rates of 0.5-5 m/Ma for best fit scenarios. These features are observed for 90-100% of the 10 Be best inversion models (i.e. with varying sedimentation rates and production schemes); these conclusions are not sensitive to the muonic production scheme.

Discussion

Cosmogenic nuclide data show that the deposition of the copper-rich layer occurred during or just before a period of low sedimentation rates sometime between 10 and 14 Ma ago.

Robustness of the analysis

The analysis was performed for a source elevation of 2200 m, similar to the current mining pit elevation. It is possible that the source elevation was different at the time of deposition. The effect of this would be a higher initial content in cosmogenic nuclides (the production at 3000 m above sea level is 50% more than at 2200 m). Assuming an elevation that, 15 Ma ago, was 1000 m higher than today and considering that an important episode of Andean uplift has been documented as having occurred in the Miocene (probably a maximum given that the apatite fission tracks and U-Th/He ages are older than 30 Myr in this area; Sanchez et al. 2018) the difference in the cosmogenic nuclide concentration due to a production rate variation would be lower than those due to the variations in the denudation rates that we explored (1-1000 m/Ma). As a result, we consider our findings to be robust regardless of the initial elevation: the denudation rate thresholds discussed in the next paragraph are slightly offset towards higher denudation rates for higher source areas. It is also possible that the Chilean forearc was uplifted ~1 km in late Miocene (e.g., [START_REF] Riquelme | A geomorphological approach to determining the Neogene to Recent tectonic deformation in the Coastal Cordillera of northern Chile (Atacama)[END_REF]Jordan et al. 2014). In that case, all of Page 18 of 79 FOR REVIEW PURPOSES ONLY Basin Research our samples may have been eroded and deposited at lower elevation, with a smaller production rate. Again, this difference is included in the range of denudation rates tested. We also tested the effect of the density used for the sedimentary column: varying it between 1800 and 2500 kg/m 3 only changes our conclusions with regards to younger sedimentation ages for denser sediment infilling. It does not significantly affect our deductions and only shifts our conclusions towards slightly younger sedimentation ages if the material density is considered (cf. Supporting Information). The fit is slightly better for higher densities because a higher density limits the cosmogenic nuclide production in samples at great depth. For these samples, the predicted cosmogenic nuclide concentrations are too high, particularly with low source denudation rates. The two pits investigated are complementary and provide information about the history of the denudation/sedimentation rates (Table 5). Data from the Tesoro Central pit show that, before 9.5 Ma ago, there was a period of rapid sedimentation (more than 50 m/Ma) of a material produced in a source area subject to high denudation (more than 250 m/Ma). This period was probably short, spanning about 1 Ma, the exact timing of which remains unclear: sometime between 14 and 10 Ma ago. The short duration of this episode of rapid sedimentation makes it compatible with the long-term averaged low denudation rates recorded in the area (16-35 m/Myr from the Oligocene to late Miocene; Arancibia, Matthews, and De Arce 2006). After 9.5 Ma (and before ~7 Ma ago), the source denudation rate and basin sedimentation dropped but remained significant, probably higher than 50 m/Ma. This is higher than what was observed by Davis et al. (2014) for the same period further south (1-10 m/Ma). In the two pits, the sedimentation rate post 9.5 Ma is lower than 2 m/Ma, which is similar to what Davis et al. ( 2014) observed (Table 5). Currently, the Centinela Basin is fed by a 2041 km 2 -wide catchment. The sedimentary basin itself has a surface area of 204 km2, or one tenth of the catchment area. If all of the sediment was retained by the basin, its long-term sedimentation rate would be ten times the denudation rate. If a sediment bypass occurred, this rate should be less. Assuming that the feeder catchment has not changed much over the last 15 Ma, which seems reasonable for the Atacama, a catchment denudation rate as high as 250 m/Ma would have filled the Centinela Basin in a very short amount of time (50 ka). This duration may be correct, corresponding to a very transitory stage; our data cannot rule it out. This duration could also be overestimated due to a smaller contributing area, as proposed below.

High denudation rates for the Atacama

It is surprising that large denudation/sedimentation rates occurred after the exotic copper deposition (sometime between 10 and 14 Ma BP) and before the 9.5 Ma-old ignimbrite, while hyper-aridity was established (e.g., [START_REF] Sillitoe | Age of Supergene oxidation and enrichment in the chilean porphyry copper province[END_REF]Dunai, Lopez, and Juez-Larre 2005;[START_REF] Rech | Neogene climate change and uplift in the Atacama Desert, Chile[END_REF][START_REF] Rech | Evidence for the development of the Andean rain shadow from a Neogene isotopic record in the Atacama Desert, Chile[END_REF][START_REF] Evenstar | Multiphase development of the Atacama Planation Surface recorded by cosmogenic 3He exposure ages: Implications for uplift and Cenozoic climate change in Western South America[END_REF]Jordan et al. 2014;[START_REF] Oerter | Early to Middle Miocene climate in the Atacama Desert of Northern Chile[END_REF]. Sedimentation rates up to 100 m/Ma and denudation rates of more than 250 m/Ma are unexpected and have never been mentioned in the literature [START_REF] Carretier | Review of erosion dynamics along the major N-S climatic gradient in Chile and perspectives[END_REF], with the exception of the very rapid incision rate of the Loa River in the Pleistocene (~1800 m/Ma; Ritter et al., 2018). For example, paleo-denudation rates deduced from 10 Be concentrations in sediment from the El Diablo formation, 400 km north of our study area, have remained on the order of 1-15 m/Ma between 12.8 and 10.3 Ma ago [START_REF] Madella | 10Be-inferred paleo-denudation rates imply that the mid-Miocene western central Andes eroded as slowly as today[END_REF]). Yet, our findings appear robust with respect to different cosmogenic scaling schemes. Compared to long-term denudation rates, these values > 250 m/Ma are still high. The thermochronological data provided by Sanchez et al. (2018) obtained in this area imply 2.5 to 3 km of denudation during the last 30-50 Ma (average denudation rates of 50-100 m/Ma). Considering that the denudation occurred mainly before 10 Ma ago (e.g., [START_REF] Arancibia | K-Ar and 40Ar/39Ar geochronology of supergene processes in the Atacama Desert, Northern Chile: Tectonic and climatic relations[END_REF]Riquelme et al., 2018), the average denudation rates deducted from the data of Sanchez et al. (2018) increase up to 150 m/Ma (denudation of 3 km during the period 30-10 Ma ago). One probable scenario is the occurrence of a wetter period before 10 Ma ago. In fact, Ritter et al. (2018) showed that river incision is strongly limited by the available water in Atacama. By dating a Pleistocene lake to the north of the Centinela District, they found that the ~500 m incision of the Loa River occurred very rapidly in the last ~270 ka, during a wetter period.

If the climate alone is responsible for these large paleo-denudation rates, then hyper-aridity must have taken place in this particular area at about 10 Ma ago. A second possibility is that the sedimentation was constrained by fault activity. For example, Sanchez (2017) produced thermochronological data suggesting activity of a nearby major fault in late Miocene between the Precordillera and the Atacama Salar (see location in Figure 2.A). In this case of active tectonics, the expected denudation/sedimentation signal must have been transient, with fast denudation/sedimentation. To explain these high denudation rates, another hypothesis could be that the basin records a regressive erosion wave during pediment emplacement (Figure 13). Based on sedimentological facies and detrital zircons, Riquelme et al. (2018) proposed a pedimentation phase during late Miocene in the same area based on sedimentological and provenance evidence. The existence of persistent steep and elongated reliefs in the region, interpreted as back-scarp relief [START_REF] Paskoff | The Quaternary of Chile: The state of research[END_REF]Riquelme et al., 2018) suggests that the pedimentation process could have been proceeded by back-scarp retreat (Figure 13). Locally at the position of the back-scarp, where the topography is steeper, the denudation rates may be much higher than the average regional value [START_REF] Strudley | Sensitivity analysis of pediment development through numerical simulation and selected geospatial query[END_REF], providing most of the sediment delivered to our study basins. This average regional denudation rate could therefore have been higher 10 Ma ago (see next paragraph). A higher transient and localized denudation rate would be consistent with the strong slope control of the watershed denudation rate documented in Chile [START_REF] Carretier | Slope and climate variability control of erosion in the Andes of central Chile[END_REF] and elsewhere (e.g. [START_REF] Binnie | Tectonic uplift, threshold hillslopes, and denudation rates in a developing mountain range[END_REF].

Hyperaridity onset timing

The date for the onset of hyperaridity in Atacama has been extensively discussed based on sedimentological arguments (e.g., Hartley and Chong 2002), surface exposure ages (e.g., Dunai et al., 2005) and supergene mineralization ages (e.g., [START_REF] Reich | Supergene enrichment of copper deposits since the onset of modern hyperaridity in the Atacama Desert, Chile[END_REF]. The proposed timing for hyperaridification includes Oligocene to Pleistocene ages, and progressive-to-abrupt changes. Ritter et al. According to these authors, the driest places can have undergone hyper-arid conditions since late Miocene or even Oligocene, whereas other locations have been subjected to varying conditions with alternating arid periods and wetter local conditions. Our data strongly suggest that, during the Neogene, there was a decrease in the denudation rates of the hills in this Atacama region that have provided sediments to our studied basin. The average denudation rate decreased from > 250 m/Ma between 14-10 Ma (Tesoro Central data) to > 50 m/Ma between 9.5-7 Ma (Mirador data). Nowadays, these rates are much lower at < 10 m/Ma (e.g., Placzek et al., 2010;Ritter et al., 2018). This decrease can be explained solely by the hills surrounding the Centinela basins having a smaller slope (Figure 13). The pedimentation and progressively increasing distance between the source and the basin evidenced by Riquelme et al. (2018) during the Miocene must have been associated with a scarp retreat and relief decrease, as well as decreasing denudation rates. The slope is indeed a decisive control on denudation in Chile [START_REF] Carretier | Review of erosion dynamics along the major N-S climatic gradient in Chile and perspectives[END_REF]. This does not discard the possibility that progressive hyper-aridification during the Neogene also contributed to the documented denudation decrease. Furthermore, in the basin at the Tesoro Central pit, the sedimentation rate dropped sharply after ~10 Ma. As discussed above, local tectonic conditions controlling the accommodation space as well as the upstream variations in the source area may explain this decrease. Recent research on the eastern border of the Precordillera suggests that local exhumation occurred during the Mid-Miocene from which we can assume a reactivation of the drainage and a higher denudation rate (Sanchez et al., in prep). This does not discard the hypothesis that hyperaridification played a role. In conclusion, both geomorphological and climatic variations can explain our data.

Supergene copper layer dating

In this framework, the Tesoro Central copper-bearing layer is likely to be 10-14 Ma-old (Figure 9). It is important to note that this age cannot be much older, simply because there would be no detectable 10 Be left in the deepest samples. This age is much younger than the age of ~21 Ma attributed to this layer by lateral correlation [START_REF] Oerter | Early to Middle Miocene climate in the Atacama Desert of Northern Chile[END_REF] with another exotic layer in the Tesoro NE pit found at a distance of 3 km (Figure 2), where supergene minerals were dated by Riquelme et al. (2018). On the contrary, our ages correspond well to the age range of other supergene mineralizations dated at 15-12 Ma in the same district (Figure 2) (Riquelme et al., 2018). This implies that the other exotic deposit in Tesoro Central, above the one we dated, is younger than 10-14 Ma and older than the 9.5 Ma ignimbrite. We therefore provide the first evidence of two exotic deposits in this district in a restricted period between 14 and 9.5 Ma. The exotic layer we have dated corresponds to a particular stage in the geomorphological evolution of this region. It terminates with a stage of low sedimentation (preceding the episode of high sedimentation), for which the best inversions of the 10Be data give median values around 0.5-5 m/Ma. This low sedimentation rate, contemporaneous with the supergene mineralization, is consistent with other studies on the same copper-bearing layer. The low field magnetic susceptibility (AMS) has shown that exotic copper deposits correspond to lower sedimentation rates [START_REF] Pizarro | The origin of the magnetic Page 30 of 79 FOR REVIEW PURPOSES ONLY Basin Research record in Eocene-Miocene coarse-grained sediments deposited in hyper-arid/arid conditions: Examples from the Atacama Desert[END_REF]. Copper minerals infilling the sediment porosity in beds truncated by erosion indicate that exotic mineralization is syngenetic to sedimentation and occurs near the surface under high evaporation rates, as expressed by C and O isotopy [START_REF] Fernández-Mort | A genetic model based on evapoconcentration for sediment-hosted exotic-Cu mineralization in arid environments: The case of the El Tesoro Central copper deposit, Atacama Desert, Chile[END_REF].

Conclusions

In this study we have combined data from two cosmogenic nuclides ( 10 Be and 21 Ne) in order to date and rate mid-Miocene denudation and clastic deposition rates with the aim to better understand the evolution of the late Miocene landscape and the conditions in which exotic copper deposits form in the Atacama Desert. For the first time, we have proven that in-situ produced cosmogenic nuclides (here the 10 Be/ 21 Ne pair) are useful to provide constraints on the dynamics, age, and conditions of an ore deposit formation: the studied exotic layer deposited between 10 and 14 Ma ago, which is almost 10 Ma younger than previously reported by lateral correlation. Moreover, the vertical profile within this layer suggests that it emplaced during a low-deposition rate (quiescent) episode (sedimentation rate of the order of few m/Ma). Exotic copper mineralization is probably promoted by a near-surface position under a highevaporation setting [START_REF] Pizarro | The origin of the magnetic Page 30 of 79 FOR REVIEW PURPOSES ONLY Basin Research record in Eocene-Miocene coarse-grained sediments deposited in hyper-arid/arid conditions: Examples from the Atacama Desert[END_REF][START_REF] Fernández-Mort | A genetic model based on evapoconcentration for sediment-hosted exotic-Cu mineralization in arid environments: The case of the El Tesoro Central copper deposit, Atacama Desert, Chile[END_REF]. Our 10 Ne/ 21 Ne data also established the temporal evolution of the denudation rates in the area which drop around 10 Ma, confirming in the Atacama Desert the onset of hyperaridity in late Miocene proposed by other authors. The current extremely low denudation rate (of the order of 1 m/Ma) has not been continuous for the last 10 Ma. Our data records a > 50 m/Ma denudation rate for the period ~7-10 Ma ago. The preceding period (roughly 10-14 Ma ago) recorded even higher denudation rates, of more than 250 m/Ma, contemporaneous to sedimentation rates over 50 m/Ma. The decrease in the post-14-10 Ma denudation rates records either a progressive aridification of the climate or a slope decrease associated with active tectonics or pediment development, or possibly both phenomena acting at the same time. Consequently, we do not recommend using our results to argue for a progressive (using the paleo-denudation record), or drastic (using the paleo-sedimentation record) establishment of hyperaridity. Our data further support the hypothesis that 14-10 Ma was a crucial time for the landscape evolution in the western Central Andes and that this change (whatever it is, tectonic and/or climatic) was concomitant with the occurrence of copper mineralizations. The success of our analysis was probably favored by the local large thickness of the sedimentary deposits, allowing for more-detailed records than elsewhere within the regional framework. Although sediments this old (> 10 Ma) have only rarely been used for cosmogenic nuclide analyses, our work provides evidence for the potential of cosmogenic nuclide geochemistry and helps push the limits of this technique following recent advances (e.g., [START_REF] Charreau | Paleo-erosion rates in Central Asia since 9Ma: A transient increase at the onset of Quaternary glaciations?[END_REF]Davis et al. 2014;[START_REF] Val | A practical tool for examining paleoerosion rates from sedimentary deposits using cosmogenic radionuclides: Examples from hypothetical scenarios and data[END_REF][START_REF] Madella | 10Be-inferred paleo-denudation rates imply that the mid-Miocene western central Andes eroded as slowly as today[END_REF]. 7 Tables Table 1. Cosmogenic production schemes, derived from Granger and Muzikar (2001, GR), Braucher et al. (2011, BH and BR), [START_REF] Heisinger | Production of selected cosmogenic radionuclides by muons: 2. Capture of negative muons[END_REF]2002, labelled H and for Neon production in GR, BR, HS). 10 Be production SLHL is set to 4.15 at/g/a (Martin et al., 2017), and the 21 Ne/ 10 Be ratio is 4.12 (Balco and Shuster 2009a;[START_REF] Kober | The cosmogenic 21Ne production rate in quartz evaluated on a large set of existing 21Ne-10Be data[END_REF]. 1 for further details). Figure 9: Reference inversion for the El Tesoro mining pit (BR). (A) The color corresponds to the χ 2 value: light yellow to brown, where a darker color is a better fit; the grey areas correspond to the tested scenario leading to improbable χ 2 values. The sample positions correspond to the ticks on the left; the copper layer is highlighted in turquoise. The inversion is constrained at three positions: arbitrary initial (t = 20 Ma, z=-160 m), ignimbrite layer (t = 9.5 ± 0.3 Ma, z = -10 m) and surface (t = 0, z = 0). (B) Explanations of how to read this graph. Figure 10. Cosmogenic isotope concentration (reference inversion) according to depth (Tesoro Central), A. for 10 Be and B. for 21 Ne. For both figures, the light colors correspond to every Monte Carlo scenario tested; the bold lines represent the best χ² scenario for 10 Be only, 21 Ne only and for both nuclides in blue, red and black, respectively. The circles and associated horizontal lines indicate the measured concentrations and their related uncertainties. Figure 11. Best χ 2 for El Tesoro in function of the source area denudation rate for the period older than 9.5 Ma, for various production schemes for both nuclides ( 10 Be and 21 Ne, logarithmic χ 2 -scale). The points indicate the best χ 2 from the inversions, the trend is drawn as lines. Figure 12. χ 2 for the El Mirador pit (without MIR-01, which derives from an ignimbrite) in function of the source area denudation rate for the period younger than 9.5 Ma, for various production schemes for either 10 Be (top, linear χ 2 -scale) or 21 Ne and 10 Be data (bottom, logarithmic χ 2 -scale). The latter shows that low values are reached for denudation rates higher than ~40 m/Ma. Figure 13. Back-scarp retreat model. It is possible that the basins were roughly located at the location of a scarp ~12 Ma ago, with the rapidly eroding scarp (ε > 250 m/Ma) as the main source of sediment. Subsequently, the back-scarp gradually retreated to the present, with an intermediate period marked by intermediate denudation rates and the Artola ignimbrite deposition at 9.5 Ma BP. The current state is characterized by low denudation rates (< 10 m/Ma).

Data Sharing and Data Accessibility

The data that support the findings of this study are found in the core of the paper, except the code IMIS, openly available in GitHub at https://github.com/regard-vincent/IMIS.

Sample preparation

Samples were first crushed and sieved to select the granulometric fraction between 0.5 and 1 mm. Magnetic minerals were separated from the bulk by a magnetic separator (Frantz L-1). Then, the nonmagnetic fractions underwent a series of leaching steps with a mixture of concentrated hydrochloric and hexafluorosilisic acids to remove all minerals but quartz. Meteoric 10 Be was removed from quartz by three partial dissolutions with concentrated hydrofluoric acid (Brown et al., 1991). Decontaminated quartz was then divided into two aliquots.

The first aliquots were used for 10 Be analysis at GET (except MIR-10, see Error! Reference source not found.). Decontaminated quartz was totally dissolved with concentrated hydrofluoric acid after adding ~310 μg of 9 Be carrier (~2.4 x 10 19 atoms of 9 Be, Table 2). The resulting solutions were evaporated until dryness and samples were re-dissolved with hydrochloric acid.

Meanwhile the sample preparation the grain morphology was observed and specific grain shapes were observed. In sample MIR13-01, , which is stratigraphically just above the 9.5 Ma-old ignimbrite (De Silva, 1989;Riquelme et al., 2018), the quartz minerals present bipyramidal shapes (see Error! Reference source not found.7). This crystal automorph shape suggests that it has a volcanic origin and was not transported over a long distance. MIR13-01 quartz minerals are thus likely to come from upstream erosion of the 9.5 Ma-old ignimbrite.

Afterwards, samples passed through an anion exchange column to remove iron and a cation exchange column to discard boron and recover Be. Finally, the eluted Be was precipitated to Be(OH) 2 with concentrated ammonia and oxidized to BeO. After target preparation at CEREGE by mixing Niobium powder with the BeO, the 10 Be/ 9 Be ratios were measured by Accelerator Mass Spectrometry (AMS) at the French National AMS Facility ASTER of CEREGE in Aix-en-Provence [START_REF] Arnold | The French accelerator mass spectrometry facility ASTER: Improved performance and developments[END_REF]. The measured 10 Be/ 9 Be ratios were calibrated against a house standard STD-11 with an assigned value of (1.191 ± 0.013) x 10 -11 (Braucher et al., 2015). This calibration procedure is similar to the KNSTD07 standardization (Nishiizumi et al., 2007;Braucher et al., 2015). Analytical 1σ uncertainties include uncertainties in AMS counting statistics, uncertainty in the 10 Be/ 9 Be standard, an external AMS error of 0.5% [START_REF] Arnold | The French accelerator mass spectrometry facility ASTER: Improved performance and developments[END_REF], and a chemical blank measurement. In all computations, a 10 Be half-life of (1.387 ± 0.01) x 10 6 years was used (Chmeleff et al., 2010;[START_REF] Korschinek | A new value for the half-life of 10Be by Heavy-Ion Elastic Recoil Detection and liquid scintillation counting[END_REF].

The second quartz aliquots were used for measuring the cosmogenic 21 Ne concentration at the CRPG Nancy noble gas lab. The purity of the quartz samples was checked under a binocular microscope and completed by DRX analysis. Quartz samples were packed in tin foil and loaded in a custom designed carrousel resistance furnace [START_REF] Zimmermann | A New Single Vacuum Furnace Design for Cosmogenic 3He Dating[END_REF] connected to a purification line with a cryogenic trap. Neon isotope abundances were measured with the Split Flight Tube mass spectrometer dedicated to the cosmogenic noble gas analysis (Vermeesch et al., 2015). The extraction of neon by quartz step-heating, gas purification and analytical procedures was similar to the procedures described in Sartégou et al. (2018). Computation of the atmosphere-corrected cosmogenic 21 Ne concentration ( 21 Ne cos ) was performed following:

21 Ne cos = R c  20 Ne atm  (R m -R a )/(R c -R a ), (equation 2)
where 20 Ne m (at.g -1 ) is the measured 20 Ne concentration in quartz, R c = 0.8 the cosmogenic 21 Ne/ 20 Ne production ratio (Niedermann, 2002); R m is the measured 21 Ne/ 20 Ne ratio and Ra = 0.002905 is the atmospheric 21 Ne/ 20 Ne ratio [START_REF] Honda | Redetermination of the 21Ne relative abundance of the atmosphere, using a high resolution, multi-collector noble gas mass spectrometer (HELIX-MC Plus)[END_REF] (Figure A1). The spallation line is computed assuming a pure mixing between the atmospheric end members (blue square, the neon isotopic ratios for air are from [START_REF] Honda | Redetermination of the 21Ne relative abundance of the atmosphere, using a high resolution, multi-collector noble gas mass spectrometer (HELIX-MC Plus)[END_REF] and assuming a 22 Ne/ 21 Ne production ratio of 1.1 (Niedermann, 2002). kg/m3 χ 2 10-20 Not significantly different for higher densities. Increases for lower densities up to ~60 (worse fit), except for the GR production scheme Figure A12 Table 1

. Main parameters tested for a sensitivity analysis

The effect of the main parameters tested is found in Table A1.

Reference inversion

The following Figure A2 shows the inverted sedimentation rate as a function of depth. This figure highlights the different sediment phases (Figure A2). Before basin infilling (we note that this phase is poorly constrained by our sampling strategy), the sedimentation rate was in the range 10 -7 -10 -5 m/a (0.1-10 m/Ma). During basin infilling (depth between ~105 and ~10 m), the sedimentation rate increased to 10 -5 -5 10 -4 m/a (10-500 m/Ma). It has then dropped to less than 10 -6 m/a (< 1 m/Ma) for the last 10 Ma. In the following, we present the results from the reference inversion with the other production schemes used. As a reminder, the different schemes used are called GH, BH, HS and BR (see Error! Reference source not found. and Error! Reference source not found. for more details). The first letter stands for the 10 Be production scheme: G stands for Granger and Muzikar (2001), B for Braucher et al. (2011), H for Heisinger et al. (2002) formulation with the updated muon interaction parameters given by Balco (2017). The second letter is indicative of the 21 Ne production scheme: H and S stands for [START_REF] Heisinger | Production of selected cosmogenic radionuclides by muons: 2. Capture of negative muons[END_REF]R for Braucher et al. (2011); 10 Be production SLHL is set to 4.15 at/g/a (Martin et al., 2017), and the 21 Ne/ 10 Be ratio is 4.12 (Balco & Shuster, 2009;[START_REF] Kober | The cosmogenic 21Ne production rate in quartz evaluated on a large set of existing 21Ne-10Be data[END_REF]. The reference is model BR.

Reference inversion, BH production scheme

The constant denudation rate is 500 m/Ma. The next figures correspond to inversion with BH production systematics; B indicates the spallation and the muon attenuation and productions are those from Braucher et al. (2011) for 10 Be. For 21 Ne, the attenuation scheme follows the definition by [START_REF] Heisinger | Production of selected cosmogenic radionuclides by muons: 2. Capture of negative muons[END_REF]. The comparison between Figure A3 and Figure 9 indicates that this inversion produces similar results, but that they are shuffled by a couple of very different likely scenarios (i.e., those on the right, at around 18-20 Ma). Disregarding these rare scenarios leads to the conclusion that the probable age of the copper layer is around 10-16 Ma).

Figure A4 shows that the data are satisfactorily adjusted by the best-fit models. Both 10 Be only and 10 Be/ 21 Ne best fit models show a hump, produced by low sedimentation rates during and after deposition of the copper-rich layer. The associated sedimentation rates are shown in Figure A5. Figure A5. Sedimentation rate vs. depth in the reference inversion with the BH production scheme. The black, blue and red lines correspond to the best fit scenario for both 10 Be and 21 Ne, 10 Be and 21 Ne only, respectively. This complex graph basically indicates that the copper layer deposition is characterized by relatively low sedimentation rates and is followed by even lower sedimentation rates (depth ~100 m). A large increase in sedimentation rates is observed from a depth of 95-100 m to a depth of 10 m (Artola ignimbrite). The last 10 Ma, corresponding to the last 10 m is characterized by very low sedimentation rates (~10 -6 m/a).

Reference inversion, GR production scheme

The denudation rate is still at 500 m/Ma. The next figures correspond to inversion with GR production systematics; G indicates the spallation and muon attenuation and productions are those from Granger and Muzikar (2001) for 10 Be. For 21 Ne, the attenuation scheme follows the definition by [START_REF] Heisinger | Production of selected cosmogenic radionuclides by muons: 2. Capture of negative muons[END_REF].

The comparison between Figure A6 and Figure 9 indicates that, similarly to what observed with production BH (Figure A3), this inversion produces similar results, leading to the conclusion that the probable age of the copper layer is around 10-14 Ma.

As expected, Figure A7-B is similar to Figure A4-B. On the contrary, the comparison of Figure A7-A with Figure A4-A and Figure 10 indicates that the GR production scheme can produce lower 10 Be concentrations, and is the most suitable in this case.

The sedimentation rates (Figure A8) and infilling scenarios (Figure A6) indicate, as shown in the other production schemes, that the copper-rich layer was deposited during a period of low sedimentation rates.

Reference inversion, HS production scheme

The denudation rate is still at 500 m/Ma. The next figures correspond to inversion with HS production systematics; the attenuation schemes for both nuclides are taken from the formulation given by [START_REF] Heisinger | Production of selected cosmogenic radionuclides by muons: 2. Capture of negative muons[END_REF] with the updated muon interaction parameters described by Balco (2017). It should be noted that this scheme does not use exponential approximations for the muon production at depth but instead propagates the muon fluxes through the Earth's surface, quantifying nuclide production as a function of their spallation reaction cross-section and capture probability.

Figure A9 highlights a limited number of very fit scenarios which result in an age of ~13 Ma for the copper layer. But this apparent precision hides a greater variability than that seen with other production schemes (see Figure A9). This may be due to the fact that this production scheme hardly produces 10 Be concentrations as low as those observed in our analyses concentrations (Figure A10).

The dispersion of the scenarios can also be seen in the sedimentation rates: the different stages of evolution can be seen on the graph (Figure A11), but they are much less marked than for the other production schemes.

Density in the reference experiment

This section shows experiments based on the El Tesoro reference inversion (density of 2500 kg/m 3 ) but with variable sedimentary layer densities of 1900, 2100, and 2500 kg/m 3 . If the sediment filling the basin were denser, Χ 2 would be lower (from ~60 for 1900 kg/m3 to 20 for 2200-2500 kg/m 3 , Figure A12) and the sedimentation ages would shift slightly to younger ages (comparison between Figure A13, Figure A14, Figure A15 and Figure 9). The Granger (GR) model stands out for its ability to fit even at all densities.

Reference inversion for the El Mirador pit

The El Mirador pit inversion was treated as the reference inversion for El Tesoro (BR production scheme), but with a source erosion rate = 300 m/Ma. We recall that the concentration of 21 Ne in the deepest part of the pit could not be measured. The data do not allow the inversions to define a precise history for the period before 10 Ma ago. They favor a relatively continuous sedimentation between 20 and 30 Ma for the bottom (top of the ore body, 70 m below the surface) and 10-20 Ma just below the Artola ignimbrite (Figure A16. Age of the sediments (Ma) in function of the depth (m) in the Mirador Mine, using the BR production parameters. The black, blue and red lines correspond to the best fit scenario for both 10 Be and 21 Ne, 10 Be and 21 Ne only, respectively.Figure A16).

The agreement with the data is not satisfactory (Figure A17). The 10 Be concentration of MIR-11 (45 m deep) cannot be modeled (it is much too low). The concentration data from MIR-01 (18 m depth) are low but this can be explained by a zero concentration acquired during the exhumation as it comes from the Artola ignimbrite (cf. bipyramidal quartz, Figure 7).

As discussed in the paper, Mirador provides more solid information regarding the period after 10 Ma. In order to better explore this period, we have inverted the three corresponding data only (in descending order MIR-05, MIR-04 and MIR-01, Figure A18). It shows that sedimentation was fastest between 10 and 8 Ma (up to samples MIR-04 and MIR-05, at a depth of 12-13 m) and was then relatively continuous. No significant change in χ 2 is observed for inversions with various initial source erosion rates. For reference, we fixed the source erosion rate at 3 m/Ma. The inversion is based on 10 Be and 26 Al here. The various inversions processed with varying source erosion rates show that sedimentation at the bottom of the sequence began at ~8 Ma ago (Figure A19). The sediments appear to have been quicker around 8 Ma BP compared with the next period up to current times (Figure A20). These conclusions are similar for various source erosion rates and for various production schemes.

  proposed that this debate can be reconciled by taking local climates in Atacama into account.

Figure 2 A

 2 Figure 2 A. Location of the Centinela District via an oblique view of northern Chile in Google Earth. B. Geological map modified after Riquelme et al. (2018) 1. Post-mid-Miocene poorly consolidated gravel deposits constituting the alluvial fans observed on the landscape surface; 2. Eocene mineralized porphyry intrusions (45-39 Ma) 3. Upper Cretaceous sedimentary and volcanic rocks. 4. Cretaceous and Paleocene intrusions. 5. Jurassic calcareous rocks. 6. Upper Paleozoic and Triassic basement. E. Esperanza gravels. I, TII and TII. Tesoro I, II and TIII gravels, respectively. At. Atravesado gravels. Ar. Arrieros gravels. A-A' shows the location of the structural profile C.

Figure 4 :

 4 Figure 4: Aerial views of the Tesoro Central and Mirador open-pit mines (A. and B., respectively) with sampling paths. 1. View of part of the Tesoro Central sampling path focused on the exotic-Cu ore deposit layer (highlighted in turquoise) with sample locations (for the entire column sampling refer to Figure 5). 2. View of the Mirador open-pit mine sampling path with the contact between the gravels and Cu-Supergene deposit and sample locations.

1 1 2

 11 Sample preparation .........................................................................................................................Reference inversion....................................................................................................................

Figure A1 :

 A1 FigureA1: Neon isotopic ratios measured in all heating steps of the samples and the CRONUS-A standard presented in this study. The ellipses represent the 68% confidence region. The plot accounts for the covariance between errors. The colors represent the neon extraction temperature: blue, < 800°C, red, > 1200°C. The spallation line is computed assuming a pure mixing between the atmospheric end members (blue square, the neon isotopic ratios for air are from[START_REF] Honda | Redetermination of the 21Ne relative abundance of the atmosphere, using a high resolution, multi-collector noble gas mass spectrometer (HELIX-MC Plus)[END_REF] and assuming a 22 Ne/ 21 Ne production ratio of 1.1(Niedermann, 2002).

  Figure A2. Graph representing the sedimentation rate (m/a) vs. depth (m) (reference inversion, BR). The black, blue and red lines correspond to the best fit scenarios for both 10 Be and 21 Ne, 10 Be only and 21 Ne only, respectively.

Figure A3 .

 A3 Figure A3. Age of the sediments (Ma) in function of the depth (m) in the Tesoro Mine, using the BH production parameters. The black, blue and red lines correspond to the best fit scenario for both 10 Be and 21 Ne, 10 Be and 21 Ne only, respectively.

FOR

  Figure A4. Cosmogenic isotope concentration (reference inversion) in the Tesoro Central open pit using the BH parameters, according to depth; the top figure shows 10 Be and the bottom shows 21 Ne. For both figures, the light colors correspond to every Monte Carlo scenario tested; the bold lines represent the best χ² scenario for 10 Be only, 21 Ne only and for both nuclides in blue, red and black, respectively. The circles and associated horizontal lines indicate the measured concentrations and their related

  Figure A6. Age of the sediments (Ma) in function of the depth (m) in the Tesoro Mine, using the BR production parameters. The black, blue and red lines correspond to the best fit scenario for both 10 Be and 21 Ne, 10 Be and 21 Ne only, respectively.

  Figure A9. Age of the sediments (Ma) in function of the depth (m) in the Tesoro Mine, using the HS production parameters. The black, blue and red lines correspond to the best fit scenario for both 10 Be and 21 Ne, 10 Be and 21 Ne only, respectively.

Figure A12 .

 A12 Figure A12. Value of χ² in function of sedimentary basin infill density for the various schemes (reference inversion). Except for GR, the best χ² values correspond to densities between 2200 and 2500 kg/m 3 .

Figure A14 .

 A14 Figure A14. Age of the sediments (Ma) in function of the depth (m) in the Tesoro Mine (reference model for the BR production scheme), with a sediment density of 2100 kg/m 3 . The black, blue and red lines correspond to the best fit scenario for both 10 Be and 21 Ne, 10 Be and 21 Ne only, respectively.

Figure A16 .

 A16 Figure A16. Age of the sediments (Ma) in function of the depth (m) in the Mirador Mine, using the BR production parameters. The black, blue and red lines correspond to the best fit scenario for both 10 Be and 21 Ne, 10 Be and 21 Ne only, respectively.

  Figure A19. Age of the sediments (Ma) in function of the depth (m) in the dataset provided by Davis et al. (2014) from the Atacama Desert, using the GH production parameters. The black and green lines correspond to the best fit scenario for both 10 Be -26 Al and 10 Be only, respectively.

  Zimmermann, L.,Blard, P. H., Burnard, P., Medynski, S., Pik, R., & Puchol, N. (2012). A new single vacuum furnace design for cosmogenic 3He dating. Geostandards and

	Basin Research Basin Research	Page 24 of 79
	Geoanalytical Research, 36(2), 121-129.
	FOR REVIEW PURPOSES ONLY FOR REVIEW PURPOSES ONLY

Table 2 .

 2 10 Be concentrations. † denote a sample entirely processed at CEREGE. Final uncertainty is corrected for process blank, AMS standard and AMS systematic error.

	Page 33 of

Table 3 .

 3 21 Ne concentrations (cf. Supporting Information)

Table 4 .

 4 21 Ne/ 10 Be burial duration (i.e., minimum deposition time, cf. text).

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Table 5 .

 5 Summary of information on sedimentation and denudation rates inferred from the analysis presented in this work.

		Sedimentation	Source denudation
	Time period	rate (m/My)	rate (m/My)
	Present	<2	<1
	7 Ma -present	<2	<10
	9.5 -7 Ma	<2	>50
	x -9.5Ma	>100	>250
	Deposition of the copper rich layer.
	Ends sometime between 10 and 14
	Ma (= x)	0.5-5	>250
	8 Figures

Figure 1: Onset of (hyper)aridity in the Atacama Desert. A. Map of the Atacama Desert in northern Chile with study site locations and data type; the colors refer to the main morphostructural domain (CC : Coastal Cordillera, CD : Central Depression, PC : Precordillera, AS : Atacama Salar, WC : Western Cordillera). The red rectangle represents the Centinela District position. B. Review of the aridity and hyperaridity onset timing inferred from various methods (method indicated in square in B.); light grey for aridity and dark grey for hyperaridity.

  Sedimentary columns of the Tesoro Central and Mirador open-pit mines (adapted from[START_REF] Fernández-Mort | A genetic model based on evapoconcentration for sediment-hosted exotic-Cu mineralization in arid environments: The case of the El Tesoro Central copper deposit, Atacama Desert, Chile[END_REF] with the sampling depths, gravel formation names and sedimentary details. The 9.52 ± 0.02 Ma age for the Artola ignimbrite has been measured byRiquelme et al. (2018). Figure6: The conceptual model upon which the inversion is designed. There are two independent steps in the clast history. First, they erode upstream and are transported toward the sedimentary basin (box 1 of the inversion program) and, second, they are covered by sediments during the basin infilling (box 2 of the inversion program). Figure7: Bipyramid automorph quartz found in MIR13-01 reworked from 9.5 Ma-old ignimbrite(Riquelme et al. 2018) Figure8. Production vs. depth (log scale) for the different schemes (left: 10 Be; right: 21 Ne). The different colored lines represent the different production rate schemes tested: GH, BH, HS and BR (see Table

	Basin Research	Page 36 of 79
	Figure 5:
	FOR REVIEW PURPOSES ONLY

  Reference inversion, production scheme BH ..........................................................................4 2.2 Reference inversion, production scheme BR...........................................................................7 2.3 Reference inversion, production scheme HS...........................................................................9 3 Density in reference experiment...................................................................................................11 4 Reference inversion for el Mirador pit ..........................................................................................13 5 Test inversion for Davis et al. 2014 data .......................................................................................15

	.....3
	2.1

This work received support (both field and laboratory expenses) from the IRD. The PhD of CS was funded by UCN (Antofagasta) and CONICYT. We would like to acknowledge Fondecyt project no. 1121049. Other significant support was provided by COPEDIM and University Paul Sabatier. We acknowledge AMSA for pit access and sampling facilities.

FOR REVIEW PURPOSES ONLY Basin Research cosmogenic nuclides: Theory, techniques, and limitations. Earth and Planetary Science Letters,, 269-281. https://doi.org/16/S0012-821X(01)00309-0 Hartley, Adrian J., Chong, G., Houston, J., & Mather, A. E. (2005). 150 million years of climatic stability: Evidence from the Atacama Desert, northern Chile. Journal of the Geological Society, 162(3), 421-424. Hartley, Adrian John, & Chong, G. (2002). A late Pliocene age for the Atacama Desert:

Implications for the desertification of Western South America. Geology, 30 (1), 43-46. https://doi.org/10.1130/0091-7613(2002)030<0043:LPAFTA>2.0.CO;2 Heisinger, B., Lal, D., Jull, A. J. T., Kubik, P., Ivy-Ochs, S., Knie, K., & Nolte, E. (2002). Production of selected cosmogenic radionuclides by muons: 2. Capture of negative muons. Earth and Planetary Science Letters, 200(3), 357-369. https://doi.org/10.1016/S0012-821X(02)00641-6 Heisinger, B., Lal, D., Jull, A. J. T., Kubik, P., Ivy-Ochs, S., Neumaier, S., Knie, K., Lazarev, V., & Nolte, E. (2002). Production of selected cosmogenic radionuclides by muons 1. Fast muons. Earth and Planetary Science Letters, 200(3-4), 345-355. https://doi.org/10.1016/S0012-821X(02)00640-4 Honda, M., Zhang, X., Phillips, D., Hamilton, D., Deerberg, M., & Schwieters, J. B. (2015). Redetermination of the 21Ne relative abundance of the atmosphere, using a high resolution, multi-collector noble gas mass spectrometer (HELIX-MC Plus). International Journal of Mass Spectrometry, 387, 1-7. https://doi.org/10.1016/j.ijms.2015.05.012 Houston, J., & 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: A Journal of the Royal Meteorological Society, 23(12), 1453-1464. Jordan, T. E., Kirk-Lawlor, N. E., Blanco, N. P., Rech, J. A., & Cosentino, N. J. (2014). Landscape modification in response to repeated onset of hyperarid paleoclimate states since 14 Ma, Atacama Desert, Chile. Geological Society of America Bulletin, 126(7-8), 1016-1046. https://doi.org/10.1130/B30978.1 Kahou, Z. S., Brichau, S., Poujol, M., Duchêne, S., Campos, E., Leisen, M., d'Abzac, F.-X., Riquelme, R., & Carretier, S. (2020). First U-Pb LA-ICP-MS in situ dating of supergene copper mineralization: Case study in the Chuquicamata mining district, Atacama Desert, Chile. Mineralium Deposita, 1-14. Kober, F., Alfimov, V., Ivy-Ochs, S., Kubik, P. W., & Wieler, R. (2011). The cosmogenic 21Ne production rate in quartz evaluated on a large set of existing 21Ne-10Be data. Earth and Planetary Science Letters, 302(1-2), 163-171. https://doi.org/10.1016/j.epsl.2010.12.008 Kober, F., Ivy-Ochs, S., Schlunegger, F., Baur, H., Kubik, P. W., & Wieler, R. (2007). Denudation rates and a topography-driven rainfall threshold in northern Chile: Multiple cosmogenic nuclide data and sediment yield budgets. Geomorphology, 83(1-2), 97-Page 28 of 79 FOR REVIEW PURPOSES ONLY Basin Research 120. Kober, F., Ivy-Ochs, S., Zeilinger, G., Schlunegger, F., Kubik, P. W., Baur, H., & Wieler, R. (2009). Complex multiple cosmogenic nuclide concentration and histories in the arid Rio Lluta catchment, northern Chile. Earth Surface Processes And Landforms, 34(3), 398-412. Korschinek, G., Bergmaier, A., Faestermann, T., Gerstmann, U. C., Knie, K., Rugel, G., Wallner, A., Dillmann, I., Dollinger, G., & von Gostomski, Ch. L. (2010). A new value for the half-life of 10Be by Heavy-Ion Elastic Recoil Detection and liquid scintillation counting. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms,

Arica

The calibration was checked by analyzing CRONUS-A quartz standards on the same analytical system (Dunai et al., 2005;Vermeesch et al., 2015). All of the measured CRONUS-A standards yielded 21 Ne cos concentrations that are consistent with the range of values reported by several international laboratories (Vermeesch et al., 2015).

Sensitivity analysis