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

Caroline Sanchez, Vincent Regard, Sebastien Carretier, Rodrigo Riquelme

Salazar, P. Blard, Eduardo Campos, Stéphanie Brichaud, Maarten Lupker, Gerard Herail

► To cite this version:

Caroline Sanchez, Vincent Regard, Sebastien Carretier, Rodrigo Riquelme Salazar, P. Blard, et al. Neogene basin infilling from cosmogenic nuclides (10Be and 21Ne) in Atacama, Chile: implications for paleoclimate and copper supergene enrichment. Basin Research, 2021, 33 (5), pp.2549-2571. 10.1111/bre.12568. hal-03438822

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

<table><tr><td>Journal:</td><td>Basin Research</td></tr><tr><td>Manuscript ID</td><td>Draft</td></tr><tr><td>Manuscript Type:</td><td>Original Article</td></tr><tr><td>Date Submitted by the Author:</td><td>n/a</td></tr><tr><td>Complete List of Authors:</td><td>Sanchez, Caroline; GET, Université de Toulouse, CNRS, IRD, UPS Regard, Vincent; GET, Université de Toulouse, CNRS, IRD, UPS Carretier, Sébastien; GET, Université de Toulouse, CNRS, IRD, UPS Riquelme Salazar, Rodrigo; Universidad Catolica del Norte, Departamento de Ciencias Geológicas Blard, Pierre-Henri; Centre de Recherches Pétrographiques et Géochimiques Campos, Eduardo; Universidad Catolica del Norte, Departamento de Ciencias Geológicas Brichau, Stéphanie; GET, Université de Toulouse, CNRS, IRD, UPS Lupker, Maarten; ETH Zürich, Geological Institute Hérail, Gérard; GET, Université de Toulouse, CNRS, IRD, UPS</td></tr><tr><td>Keywords:</td><td>supergene copper deposits, Economic Geology, cosmogenic nuclides, Atacama, denudation rates, intramountainous basin, sediment flux, burial dating</td></tr></table>

SCHOLARONE™
Manuscripts
* the ¹⁰Be/²¹Ne pair of comogenic nuclides is useful to date Miocene sediments and exotic supergene enrichment

* Erosion rates higher to 250 m/Myr have been recorded during Middle Miocene in Atacama

* Progressive decrease of erosion rates at around 10 Myr ago in Atacama

* We date an exotic copper deposit at 10-14 Myrs. Another one is younger but older than 9.5 Myr.
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10 ¹GET, Université de Toulouse, CNRS, IRD, UPS, (Toulouse), France. 14 avenue Edouard Belin, 31400

11 Toulouse, France

12 ²Depto. Ciencias Geológicas, Universidad Católica del Norte, Avenida Angamos 0610, 8 Antofagasta,

13 Chile.

14 ³Centre de Recherches Pétrographiques et Géochimiques, CRPG, UMR 7358, CNRS, Université de

15 Lorraine, Vandoeuvre-lès-Nancy, France

16 ⁴ETH, Geological Institute, Sonneggstrasse 5, 8092 Zurich, Switzerland

17 ² These authors contributed equally.

18 * corresponding author: [vincent.regard@get.omp.eu](mailto:vincent.regard@get.omp.eu) tel: +33 5 61 33 26 45

19

## Acknowledgements

20 This work **received** support (both field and laboratory expenses) from **the IRD**. The **PhD of CS** was

21 funded by UCN (Antofagasta) and CONICYT. **We would like to acknowledge Fondecyt project no.**

22 **1121049**. Other significant support was provided by COPEDIM and University Paul Sabatier. We

23 acknowledge AMSA for pit access and sampling facilities. We are grateful to Régis Braucher and Laetitia

24 Leanni for constructive discussions.

25

## Abstract

26 Increasing evidence suggests that supergene exotic copper deposits were emplaced during periods of

27 geomorphic quiescence and pulses of humidity in arid environments. We tested this idea in the

28 Centinela Mining District in the Atacama Desert (northern Chile). We collected 14 sand samples at
depth (up to 110 m) in two open-pit mines (Central Tesoro and Mirador) exposing Miocene sediment, and located in the El Tesoro Basin, which hosts two exotic copper-rich layers. We inverted the ¹⁰Be and ²¹Ne concentrations by using a two-box model (IMIS, Inversion of Multi Isotopes in a Sedimentary basin) composed of an eroding source of sediment and a depositional sedimentary basin, and by selecting denudation and sedimentation rate histories that can explain our data. The ages found demonstrate that the two exotic layers were deposited during a narrow period between <14 Ma (10 Ma younger than previously thought) and 9.5 Ma, when an ignimbrite covered the sedimentary sequence. The dated lower exotic copper layer was deposited during or just before a sharp decrease in the sedimentation rates (from >100 to 0.5-5 m/Ma), which is consistent with published sedimentological and carbonate isotopic data in this district. This confirms the idea that exotic deposits form during a quiescence of the geomorphic activity. Nevertheless, our model suggests that the background denudation rate providing sediment to these basins between ~14 Ma and ~9.5 Ma was surprisingly high (>250 m/Ma) for such an arid environment. These denudation rates can be explained by a relatively rapid back-scarp retreat providing most of the sediment to these basins and possibly a wetter climate compared to the present. Then, during the period 10-7 Ma, the denudation rates decreased to >50 m/Ma. This decrease may correspond to a progressive slope decrease of the hills around, or to a progressive aridification, or a combination of both phenomena.

**Keywords:** supergene copper deposits; Atacama; cosmogenic nuclides; denudation rates; burial dating; intramountainous basin

48

# 1 Introduction

The Atacama Desert in northern Chile and southernmost Peru hosts the biggest concentration of world-class porphyry copper deposits on Earth (Sillitoe, 2010). 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., Sillitoe 2010). 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, covellite). 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., Münchmeyer 1996). 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., Arancibia, et al., 2006; Reich et al., 2009; 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; Braxton et al. 2009). 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, Fernández-Mort et al. (2017) evidenced the role of
sedimentary environments in controlling exotic copper mineralization: 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. Fernández-Mort et al. (2017) showed that some exotic copper deposits form in ephemeral distal lakes mainly by evaporation, while exotic copper deposited later mainly corresponds to the erosion of pieces of previously formed exotic copper deposits and their downstream deposition in sedimentary traps. Previous studies have suggested that low denudation and sedimentation rates are needed for the deposition of exotic copper deposits. On the contrary, there has been no quantitative estimate of the porphyry copper denudation rate and sedimentation rate in sedimentary traps during the formation of exotic copper deposits.

Recent developments in cosmogenic nuclide analytical techniques for sediment have provided new methods for estimating their paleo-denudation rates or burial ages (e.g., Balco and Shuster 2009; Charreau et al. 2011; Sartégou et al. 2018), with applications to the Atacama Desert (Davis et al. 2014; Madella et al. 2018). Here, we develop an approach based on two cosmogenic isotopes, ¹⁰Be (radioactive, half-life 1.39 Ma) and ²¹Ne (stable). We collected 14 sand samples in a Neogene sedimentary sequence exposed in two mine pits found in the Centinela Mining District (Figure 2): the Tesoro Central pit, hosting two exotic copper deposits, and the Mirador pit, where supergene mineralization and the related porphyry copper system outcrop. We developed a new two-box model (called IMIS, Inversion of Multi Isotopes in a Sedimentary basin), with one box for the eroding source of sediment and the other for the basin where they deposit. For various denudation and sedimentation rates (either fixed or random) in these two boxes, the model predicts the ¹⁰Be and ²¹Ne concentrations through time in the sedimentary sequence. Using a Monte Carlo approach, we minimize the difference between predicted and measured concentrations to infer the best-fit scenario of denudation and sedimentation and to establish a modeled age for the sediment sequence. This approach reveals subtle variations through time and constrains the age of the studied exotic copper deposit. From these
104 results, we also discuss the age and the sedimentary response to the Late Miocene aridification of the
105 Atacama region.

106 **2 Geological background and sampling**

107 **2.1 Geological background**

108 The Centinela Mining District is located at approximately 23°S, in the Precordillera
109 physiographic unit of the Andean forearc (see location in Figure 1). It is bordered by the Central
110 Depression to the west and by the Atacama Salar to the east. In the district, several copper mines are
111 currently exploited: the Tesoro Central, Tesoro NE, Esperanza, Telegrafo, Mirador and Encuentro with
112 few exploration projects still under development (Tomlinson and Blanco 1997; Mpodozis and Cornejo
113 2012).

114 In the Precordillera, the Paleozoic-Triassic basement and the sedimentary cover (Jurassic
115 marine to Upper Cretaceous continental volcano-sedimentary rocks) host intrusives, related to the
116 Late Cretaceous to Eocene magmatic arc (Marinovic and García 1999; Mpodozis and Cornejo 2012).
117 These rocks have been faulted during the Eocene tectonic phase by the Domeyko Fault System
118 (Mpodozis et al. 1993; Amilibia et al. 2008; Mpodozis and Cornejo 2012). At the regional scale, the
119 activity of the fault system resulted in the creation of intra-mountainous basins such as the Centinela
120 Basin (Mora et al. 2004; Riquelme et al. 2018). This tectonic episode was synchronous to the
121 emplacement of the Eocene metallogenic belt. In the Centinela Basin, porphyry copper systems were
122 emplaced synchronously to the movement of faults related to the Domeyko Fault System, such as the
123 Tesoro Central, Tesoro NE, Llano, Centinela, and Esperanza faults (see Figure 2). Late (< 10 Ma) fault
124 activity has resulted in the uplift of the western block where the central Tesoro mining pit is located,
125 with respect to the eastern block where the Mirador mining pit is located (Mpodozis and Cornejo
126 2012).
Supergene copper mineralization over substratum rocks and exotic copper mineralization hosted by gravel deposits can be found in the Centinela Basin (Fernández-Mort et al. 2017). 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 (Mora et al. 2004; 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 Ma-old 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 (Arancibia et al., 2006). 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 (Sillitoe and McKee 1996; Perelló 2010; Tapia et al. 2012; 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 (Tapia et al. 2012; 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).

## 2.2 Geomorphic background: denudation rates and paleoclimate

Long-term denudation rates in the Centinela District have been determined by low-temperature 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 (Maksaev and Zentilli 1999; Sanchez et al. 2018). The supergene mineral ages in the area are younger than the main exhumation phase
152 (Arancibia et al., 2006; Sanchez et al., 2018) confirming that supergene copper mineralization occurs
153 in flat landscapes characterized by low relief and low denudation rates (Mortimer 1973; Alpers and
154 Brimhall 1988; Clark et al. 1990; Mote et al. 2001; Quang et al. 2005; Sanchez et al. 2018).

155 Several studies have estimated erosion (denudation) rates at the regional scale. In the Atacama
156 Desert in northern Chile (18-30°S), for example, the current denudation rates measured by river
157 sediment loads range from 0.1 to 10 m/Ma with a notable exception on the Lluta River (~43 m/Ma,
158 Carretier et al. 2018). At the millennium scale range, cosmogenic nuclides record catchment-scale
159 denudation rates up to ~60 m/Ma (Kober et al. 2009; Cortés-Aranda J. et al. 2012; Carretier et al. 2013;
160 see Figure 3).

161 At a local outcrop scale, cosmogenic nuclides have recorded *maximum* denudation rates values
162 in the range 0.01-50 m/Ma, *with a median value lower than 1 m/Ma* (Dunai, Lopez, and Juez-Larre
163 2005; Nishiizumi et al. 2005; Kober et al. 2007; Evenstar et al. 2009; Gattacceca et al. 2011; Cortés-
164 Aranda J. et al. 2012; Owen et al. 2011; Placzek et al. 2014; Martinod et al. 2016; Ritter, Stuart, et al.
165 2018; Amundson et al. 2012). The *currently observed low denudation rates* may have lasted for
166 millions of years, without significant change in elevation (Blard et al., 2019). Gypsisoil development
167 may *provide evidence of* ~10 Ma of hyper-aridity and landform stability (rainfall < 40 mm/yr, Rech et
168 al. 2006): this *geomorphological stability* is further confirmed by the regional observation of the *Artola
169 ignimbrite dated at ~9.52 ± 0.02 Ma* covering most of the landscape surface, *affected by minor
170 reworking after deposition* (Riquelme et al. 2018).

171 On the contrary, *there are few records of the paleo-denudation rate*. Based on the cosmogenic
172 ¹⁰Be data, from north of our studied area, Madella et al. (2018) determined paleo-denudation rates
173 ranging from 0.5 to 15 m/Ma for the period 10.3-12.8 Ma ago. On the basis of estimations of porphyry
174 copper weathering rates, Arancibia et al. (2006) estimated that the denudation was less than 16-35
175 m/Ma from the Oligocene to Late Miocene. Finally, Alpers and Brimhall (1988) determined that erosion
176 rates on the order of 100m/Ma enabled the exhumation of the La Escondida porphyry copper
177 sometime between 33.7 and 18 Ma. These authors postulate that erosion dramatically decreased to
178 less than 10m/Ma after ~15 Ma due to the onset of hyperaridity.

179 **2.3 Sampling**

180 A total of 14 samples were collected in the Centinela District, distributed in two different mine
181 pits (nine samples from the Tesoro Central pit and five from the Mirador pit, see the location in Figure
182 4).

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

192

193 **3 Methods based on cosmogenic nuclides**

194 **3.1 Basic systematics**

195 In-situ cosmogenic nuclides are produced within the Earth's surface material through nuclear reactions
196 (mostly spallation but also muonic capture) **caused** by cosmic rays. Spallation processes occur within a
197 couple of meters below the Earth's surface (e.g., Lal 1991; Gosse and Phillips 2001). The concentration
198 of *in situ*-produced nuclides (i.e., produced within the crystal lattice) reflects the time the mineral spent
199 in the production zone (**c.a. from the surface to a few meters below the surface**). This is controlled by
the date of exposure initiation, the local denudation rate and the local production rate (e.g., Bierman and Steig 1996; Brown et al. 1995). 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 (Brown et al., 1995; Granger, Kirchner, and Finkel 1996). In addition, as some of the cosmogenic nuclides are radioactive (e.g. ²⁶Al, ¹⁰Be), 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 ²⁶Al/¹⁰Be pair of cosmogenic nuclides (Balco and Shuster 2009). The burial time t<sub>b</sub> is given by Equation 1, where N<sub>A</sub> and N<sub>B</sub> are nuclide concentrations at time t, P<sub>A</sub> and P<sub>B</sub> are the respective production rates, λ<sub>A</sub> and λ<sub>B</sub> are the respective decay constants (value of 0 for stable nuclides) and f is the scaling factor at the exposure location (Blard et al., 2019).

$$ \frac{P_A}{N_A}e^{-\lambda_A t_b} - \frac{P_B}{N_B}e^{-\lambda_B t_b} = \frac{\lambda_A - \lambda_B}{f} \quad (\text{equation 1}) $$

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<sub>AB</sub>(0)) depends on the production rates and on the duration of the sediment residence in the source. R<sub>AB</sub>(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 (Lal 1991; 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 ²¹Ne record the pre-burial history in a more dramatic manner than radioactive ¹⁰Be. The
homogeneity of the results discussed in the following makes the possibility of a complex pre-exposure
improbable, except for two samples with high ²¹Ne/¹⁰Be 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.

**3.2 In situ cosmogenic ¹⁰Be and ²¹Ne 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 ¹⁰Be
analysis, at GET and ASTER (except MIR-10, see **Error! Reference source not found.**).

The second quartz aliquot was used to measure the cosmogenic ²¹Ne 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.
## 3.3 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<sub>AB</sub>(0) (Blard et al., 2019). 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<sub>b</sub>) 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<sub>b</sub>).

## 3.4 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 Brown et al. 1995; Granger, Kirchner, and Finkel 1996; Heisinger et al. 2002a; Heisinger et al. 2002b; Dunai 2010; Braucher et al. 2011). P depends on the elevation of the source rock; the sensitivity tests showed that,
274 in this context, potential changes in elevation did not significantly impact the results presented
275 hereafter.

$$276 \quad C = \sum_i \frac{P_i}{\lambda + \frac{\rho e}{\Lambda_i}} \quad (\text{Equation 2})$$

277 The second step corresponds to the sedimentation in the basin (box 2, Figure 6).

278 In our model, the basin infill is divided into periods, each being bounded by well-defined events such
279 as the current surface, or in our case, the emplacement of the Artola ~9.5 Ma-old ignimbrite layer. A
280 period is divided into various sub-periods with a random duration and a random sedimentation rate;
281 the duration and thicknesses follow uniform laws whereas the sedimentation rate corresponds to the
282 ratio between thickness and duration. The number of sub-periods is fixed to seven, typically. The total
283 sedimentation during a period is adjusted (by a multiplication ratio) to satisfy its stratigraphic
284 thickness. The basement rock and sediment densities are set to 2700 kg/m³ and 2300 kg/m³,
285 respectively. Once a scenario has been drawn with its succession of sub-periods with specified
286 sedimentation rates and durations, the model time is subsampled into time steps of 5 ka to compute
287 the ¹⁰Be and ²¹Ne concentrations, as described in the following.

288 During each time step, we compute the concentrations of ¹⁰Be and ²¹Ne in two steps, first in box 1 and
289 then in box 2. In box 1, the ¹⁰Be and ²¹Ne concentrations are calculated depending on their respective
290 production rates at the elevation of the catchment, and the average catchment denudation (Equation
291 2). These concentrations are attributed to the newly deposited surface layer in the basin in box 2. At
292 each time step, the ¹⁰Be and ²¹Ne concentrations in all of the deeper layers in the basin are updated
293 taking both the decay of ¹⁰Be and the undersurface production of ¹⁰Be and ²¹Ne over the last 5 ka
294 (duration of one-time step) into account. This production strongly depends on the production scheme.
295 The production at depth is often modelled with an exponential attenuation (although not for model
296 HS, see below):

$$297 \quad P_i(z) = P_i(z=0) \cdot e^{-\rho z / \Lambda_i} \quad (\text{Equation 3})$$
Since there are different models describing the attenuation of ¹⁰Be and ²¹Ne 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 ¹⁰Be production scheme: G for Granger and Muzikar (2001), B for Braucher et al. (2011), H for Heisinger et al. (2002). The second letter is indicative of the ²¹Ne production scheme: H and S for Heisinger et al. (2002) and R for Braucher et al. (2011); ¹⁰Be production SLHL is set to 4.15 at/g/a (Martin et al., 2017), and the ²¹Ne/¹⁰Be ratio is 4.12 (Balco and Shuster 2009a; Kober et al., 2011). 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 ¹⁰Be and ²¹Ne concentrations have been updated, new ¹⁰Be and ²¹Ne 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 χ² misfit metric between the predicted and measured ¹⁰Be and ²¹Ne concentrations, defined by Equation 2.

$$ \chi^2 = \sum_i \left( \frac{C_{obs,i} - C_{mod,i}}{Err_i} \right)^2 \quad (\text{Equation 4}) $$

where Cobs,i, Cmod,i and Erri 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 χ² values, one for each single nuclide (the concentrations in Equation 2 are only ¹⁰Be or ²¹Ne ones) and one considering together the misfit for the two nuclides (χ² calculated on the entire set of ¹⁰Be and ²¹Ne data).
322

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.

323

324

325

# 4 Results

326

## 4.1 Concentrations

327

Concentrations (Tables 2 and 3) are comprised between (6 ± 4) x 10⁶ and (1.38 ± 0.09) x 10⁸ at/g for ²¹Ne (plus three samples that are below the detection limit) and are measurable for ¹⁰Be (from (1.8 ± 0.3) x 10³ at/g to (9.70 ± 0.32) x 10⁵ 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 ¹⁰Be concentration (Table 2 and Table 3).

328

329

330

331

332

## 4.2 Burial ages

333

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.

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337

338

339

340

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 χ² by one order of magnitude. Our reference inversion (production parameter BR, denudation rate = 5.10⁻⁴ m/a,

341

342

343
344 discussed below) gives two important clues. First, the deposition of the copper-rich layer is likely 10-
345 14 Ma old (Figure 9), and is followed by a stage of rapid sedimentation (~10⁻⁴ m/a, cf. appendix). In
346 fact, our misfit metric χ² is not very sensitive to input parameters, because the uncertainties are high
347 compared to the measured concentrations (10-30% for ¹⁰Be, Error! Reference source not found., 6-
348 70% for ²¹Ne, Table 3). Our interpretations are thus robust and have limited dependency on the
349 production scheme used (see appendix).

350

351

352 In the Mirador mining pit, the burial times reflect the stratigraphic order, from ~7 Ma for the top
353 samples to ~14 Ma at a depth of 45 m below the surface. The upper ~7 Ma samples stand just above
354 the 9.5 Ma-old Ar/Ar dated Artola ignimbrite, while the ~14 Ma deep samples are located dozens of
355 meters below this (Figure 5). This observation indicates that the ²¹Ne/¹⁰Be burial durations (despite
356 being minimal, not taking the production during deposition into account) are in agreement with the
357 stratigraphic order (Error! Reference source not found.). Data from the Mirador pit better constrain
358 sedimentation rate than the burial times, because the sedimentation rate is more efficient at varying
359 the concentrations than radioactive decay.

360

## 4.3 Paleo-denudation and sedimentation rates, determined by forward modelling

361

362 The initial ²¹Ne concentration in the sediments is the sum of ²¹Ne acquired before the deposition,
363 mostly during the material exhumation by denudation on hillslopes and ²¹Ne produced during
364 sedimentation. In the particular case of similar sedimentation and denudation rates, occurring at a
365 similar elevation, half of the ²¹Ne concentration comes from exposure on eroding hillslopes and half
366 from sedimentation. In this case, Equation 2 can be inverted to obtain an integrated sedimentation
367 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. Martinod et al. 2016;
Carretier et al. 2018). 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 χ²) yield relatively high denudation rates,
higher than 50 m/Ma for the period 7-9.5 Ma (Figure 12. Figure 12).

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

Our ¹⁰Be/²¹Ne data constrain the deposition age of the copper-rich layer in the Tesoro Central mining
pit between 14 and 10 Ma. Moreover, the ¹⁰Be concentration clearly increases towards the surface
(Figure 10.A) as does ²¹Ne (due to larger analytical uncertainties, this tendency is however questionable
for ²¹Ne, 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 ¹⁰Be best fits usually imply a sedimentation rate of the order of 0.5-5 m/Ma. This observation is confirmed by inversions for ¹⁰Be, 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 ¹⁰Be best inversion models (i.e. with varying sedimentation rates and production schemes); these conclusions are not sensitive to the muonic production scheme.

## 5 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., Riquelme et al. 2003; Jordan et al. 2014). In that case, all of
417 our samples may have been eroded and deposited at lower elevation, with a smaller production rate.
418 Again, this difference is included in the range of denudation rates tested. We also tested the effect of
419 the density used for the sedimentary column: varying it between 1800 and 2500 kg/m³ only changes
420 our conclusions with regards to younger sedimentation ages for denser sediment infilling. It does not
421 significantly affect our deductions and only shifts our conclusions towards slightly younger
422 sedimentation ages if the material density is considered (cf. Supporting Information). The fit is slightly
423 better for higher densities because a higher density limits the cosmogenic nuclide production in
424 samples at great depth. For these samples, the predicted cosmogenic nuclide concentrations are too
425 high, particularly with low source denudation rates.

426 The two pits investigated are complementary and provide information about the history of the
427 denudation/sedimentation rates (Table 5). Data from the Tesoro Central pit show that, before 9.5 Ma
428 ago, there was a period of rapid sedimentation (more than 50 m/Ma) of a material produced in a
429 source area subject to high denudation (more than 250 m/Ma). This period was probably short,
430 spanning about 1 Ma, the exact timing of which remains unclear: sometime between 14 and 10 Ma
431 ago. The short duration of this episode of rapid sedimentation makes it compatible with the long-term
432 averaged low denudation rates recorded in the area (16-35 m/Myr from the Oligocene to late Miocene;
433 Arancibia, Matthews, and De Arce 2006). After 9.5 Ma (and before ~7 Ma ago), the source denudation
434 rate and basin sedimentation dropped but remained significant, probably higher than 50 m/Ma. This
435 is higher than what was observed by Davis et al. (2014) for the same period further south (1-10 m/Ma).
436 In the two pits, the sedimentation rate post 9.5 Ma is lower than 2 m/Ma, which is similar to what
437 Davis et al. (2014) observed (Table 5).

438 Currently, the Centinela Basin is fed by a 2041 km²-wide catchment. The sedimentary basin itself has
439 a surface area of 204 km², or one tenth of the catchment area. If all of the sediment was retained by
440 the basin, its long-term sedimentation rate would be ten times the denudation rate. If a sediment by-
441 pass 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., Sillitoe and McKee 1996; Dunai, Lopez, and Juez-Larre 2005; Rech et al. 2006; Rech et al. 2010; Evenstar et al. 2009; Jordan et al. 2014; Oerter et al. 2016). 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 (Carretier et al. 2018), 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 ¹⁰Be 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 (Madella et al. 2018). 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., Arancibia et al., 2006; 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.
466

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.

467

468

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.

469

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471

472

473

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 (Paskoff 1977; 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 (Strudley and Murray 2007), 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 (Carretier et al., 2013) and elsewhere (e.g. Binnie et al., 2007).

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477

478

479

480

481

482

483

484

485

486

Hyperaridity onset timing

487

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., Reich et al., 2009). The proposed timing for hyperaridification includes Oligocene to Pleistocene ages, and progressive-to-abrupt changes. Ritter et al.

488

489

490
491 (2018) proposed that this debate can be reconciled by taking local climates in Atacama into account.
492 According to these authors, the driest places can have undergone hyper-arid conditions since late
493 Miocene or even Oligocene, whereas other locations have been subjected to varying conditions with
494 **alternating arid periods and** wetter local conditions. **Our data strongly suggest that, during the**
495 **Neogene, there was a decrease in the denudation rates of the hills in this Atacama region that have**
496 **provided sediments to our studied basin. The average denudation rate decreased from > 250 m/Ma**
497 **between 14-10 Ma (Tesoro Central data) to > 50 m/Ma between 9.5-7 Ma (Mirador data). Nowadays,**
498 **these rates are much lower at < 10 m/Ma (e.g., Placzek et al., 2010; Ritter et al., 2018). This decrease**
499 **can be explained **solely by the hills surrounding the Centinela basins having a smaller** slope (Figure 13).
500 The pedimentation and progressively increasing distance between the source and the basin evidenced
501 by Riquelme et al. (2018) during the Miocene must have been associated with a scarp retreat and relief
502 decrease, as well as decreasing denudation rates. The slope is indeed a decisive control on denudation
503 in Chile (Carretier et al., 2018). This does not discard the possibility that progressive hyper-aridification
504 during the Neogene also contributed to the documented denudation decrease. Furthermore, in the
505 basin at the Tesoro Central pit, the sedimentation rate dropped sharply after ~10 Ma. **As discussed**
506 **above, local tectonic conditions controlling the accommodation space as well as the upstream**
507 **variations in the source area may explain this decrease. Recent research on the eastern border of the**
508 **Precordillera suggests that local exhumation occurred during the Mid-Miocene from which we can**
509 **assume a reactivation of the drainage and a higher denudation rate (Sanchez et al., in prep). This does**
510 not discard **the hypothesis** that hyperaridification played a role. In conclusion, both geomorphological
511 and climatic variations can explain our data.

512 **Supergene copper layer dating**

513 In this framework, the Tesoro Central copper-bearing layer is likely to be 10-14 Ma-old (Figure 9). It is
514 important to note that this age cannot be much older, simply because there would be no detectable
515 ¹⁰Be left in the deepest samples. This age is much younger than the age of ~21 Ma attributed to this
layer by lateral correlation (Oerter et al., 2016) 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 (Pizarro et al., 2018). 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 (Fernández-Mort et al.,
2017).

532

533

# 6 Conclusions

In this study we have combined data from two cosmogenic nuclides (¹⁰Be and ²¹Ne) 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 ¹⁰Be/²¹Ne 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 high-evaporation setting (Pizarro et al., 2018; Fernández-Mort et al., 2017).

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., Charreau et al. 2011; Davis et al. 2014; Val and Hoke 2016; Madella et al. 2018).
564 References

565 Alpers, C. N., & Brimhall, G. H. (01). Middle Miocene climatic change in the Atacama Desert, northern Chile: Evidence from supergene mineralization at La Escondida. *GSA Bulletin*, 100(10), 1640-1656. https://doi.org/10.1130/0016-7606(1988)100<1640:MMCCIT>2.3.CO;2

569 Amilibia, A., Sàbat, F., McClay, K., Muñoz, J., Roca, E., & 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(12), 1520-1539.

573 Amundson, R., Dietrich, W., Bellugi, D., Ewing, S., Nishiizumi, K., Chong, G., Owen, J., Finkel, R., Heimsath, A., Stewart, B., & Caffee, M. (2008). Geomorphologic evidence for the late Pliocene onset of hyperaridity in the Atacama Desert. *GSA Bulletin*, 124(7-8), 1048-1070. https://doi.org/10.1130/B30445.1

577 Arancibia, G., Matthews, S. J., & Pérez de Arce, C. (2006). K-Ar and 40Ar/39Ar geochronology of supergene processes in the Atacama Desert, Northern Chile: Tectonic and climatic relations. *Journal of the Geological Society*, 163(1), 107-118.

580 Arnold, M., Merchel, S., Bourlès, D. L., Braucher, R., Benedetti, L., Finkel, R. C., Aumaître, G., Gottdang, A., & Klein, M. (2010). The French accelerator mass spectrometry facility ASTER: Improved performance and developments. *Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms*, 268(11), 1954-1959. https://doi.org/10.1016/j.nimb.2010.02.107

585 Balco, G. (2017). Production rate calculations for cosmic-ray-muon-produced 10Be and 26Al benchmarked against geological calibration data. *Quaternary Geochronology*, 39, 150-173.

588 Balco, G., & Shuster, D. L. (2009a). 26Al-10Be-21Ne burial dating. *Earth and Planetary Science Letters*, 286(3), 570-575. https://doi.org/10.1016/j.epsl.2009.07.025

590 Balco, G., & Shuster, D. L. (2009b). Production rate of cosmogenic 21Ne in quartz estimated from 10Be, 26Al, and 21Ne concentrations in slowly eroding Antarctic bedrock surfaces. *Earth and Planetary Science Letters*, 281(1), 48-58. https://doi.org/10.1016/j.epsl.2009.02.006

594 Bierman, P., & Steig, E. J. (1996). Estimating Rates of Denudation Using Cosmogenic Isotope Abundances in Sediment. *Earth Surface Processes and Landforms*, 21, 125-139. https://doi.org/10.1002/(SICI)1096-9837(199602)21:2<125::AID-ESP511>3.0.CO;2-8

597 Binnie, S. A., Phillips, W. M., Summerfield, M. A., & Fifield, L. K. (2007). Tectonic uplift, threshold hillslopes, and denudation rates in a developing mountain range. *Geology*, 35(8), 743-746.

600 Blard, P.-H., Lupker, M., & Rousseau, M. (2019). Paired-cosmogenic nuclide paleoaltimetry. *Earth and Planetary Science Letters*, 515, 271-282. https://doi.org/10.1016/j.epsl.2019.03.005
603 Braucher, R., Guillou, V., Bourlès, D. L., Arnold, M., Aumaître, G., Keddadouche, K., & Nottoli, E. (2015). Preparation of ASTER in-house 10Be/9Be standard solutions. *Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms*, 361, 335-340. https://doi.org/10.1016/j.nimb.2015.06.012

607 Braucher, R., Merchel, S., Borgomano, J., & Bourlãs, D. L. (2011). Production of cosmogenic radionuclides at great depth: A multi element approach. *Earth and Planetary Science Letters*, 309(1-2), 1-9. https://doi.org/10.1016/j.epsl.2011.06.036

610 Braxton, D. P., Cooke, D. R., Ignacio, A. M., Rye, R. O., & Waters, P. J. (2009). 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. *Economic Geology*, 104(3), 333-349. https://doi.org/10.2113/gsecongeo.104.3.333

616 Brown, E. T., Edmond, J. M., Raisbeck, G. M., Yiou, F., Kurz, M. D., & Brook, E. J. (1991). Examination of surface exposure ages of Antarctic moraines using in situ produced 10Be and 26Al. *Geochimica et Cosmochimica Acta*, 55(8), 2269.

619 Brown, E. T., Stallard, R. F., Larsen, M. C., Raisbeck, G. M., & Yiou, F. (1995). Denudation rates determined from the accumulation of in situ-produced 10Be in the luquillo experimental forest, puerto rico. *Earth and Planetary Science Letters*, 129(1-4), 193.

622 Carretier, S., Tolorza, V., Regard, V., Aguilar, G., Bermúdez, M. A., Martinod, J., Guyot, J.-L., Hérail, G., & Riquelme, R. (2018). Review of erosion dynamics along the major N-S climatic gradient in Chile and perspectives. *Geomorphology*, 300, 45-68. https://doi.org/10.1016/j geomorph.2017.10.016

626 Carretier, Sébastien, Regard, V., Vassallo, R., Aguilar, G., Martinod, J., Riquelme, R., Pepin, E., Charrier, R., Hérail, G., Farias, M., Guyot, J.-L., Vargas, G., & Lagane, C. (2013). Slope and climate variability control of erosion in the Andes of central Chile. *Geology*, 41(2), 195-198. https://doi.org/10.1130/g33735.1

630 Charreau, J., Blard, P.-H., Puchol, N., Avouac, J.-P., Lallier-Vergès, E., Bourlès, D., Braucher, R., Gallaud, A., Finkel, R., Jolivet, M., Chen, Y., & Roy, P. (2011). Paleo-erosion rates in Central Asia since 9Ma: A transient increase at the onset of Quaternary glaciations? *Earth and Planetary Science Letters*, 304(1), 85-92. https://doi.org/10.1016/j.epsl.2011.01.018

635 Chmeleff, J., von Blanckenburg, F., Kossert, K., & Jakob, D. (2010). Determination of the Be-10 half-life by multicollector ICP-MS and liquid scintillation counting. *Nuclear Instruments & Methods In Physics Research Section B-Beam Interactions With Materials And Atoms*, 268(2), 192-199.

639 Clark, A. H., Tosdal, R. M., Farrar, E., & V, A. P. (1990). Geomorphologic environment and age of supergene enrichment of the Cuajone, Quellaveco, and Toquepala porphyry copper deposits, southeastern Peru. *Economic Geology*, 85(7), 1604-1628. https://doi.org/10.2113/gsecongeo.85.7.1604
643

Cortés-Aranda J., González L. Gabriel, Binnie S. A., Robinson R., Freeman S. P. H. T., & Vargas E. G. (2012). Paleoseismology of the Mejillones Fault, northern Chile: Insights from cosmogenic 10Be and optically stimulated luminescence determinations. *Tectonics*, 31(2). https://doi.org/10.1029/2011TC002877

644

645

646

647

Davis, M., Matmon, A., Placzek, C. J., McIntosh, W., Rood, D. H., & Quade, J. (2014). Cosmogenic nuclides in buried sediments from the hyperarid Atacama Desert, Chile. *Quaternary Geochronology*, 19, 117–126. https://doi.org/10.1016/j.quageo.2013.06.006

648

649

650

651

De Silva, S. L. (1989). Altiplano-Puna volcanic complex of the central Andes. *Geology*, 17(12), 1102–1106.

652

653

Dunai, T. J., Lopez, G. A. G., & Juez-Larre, J. (2005). Oligocene-Miocene age of aridity in the Atacama Desert revealed by exposure dating of erosion-sensitive landforms. *Geology*, 33(4), 321–324.

654

655

656

Dunai, Tibor J. (2010). *Cosmogenic Nuclides: Principles, concepts and applications in the Earth surface sciences*. Cambridge University Press.

657

658

Evenstar, L. A., Mather, A. E., Hartley, A. J., Stuart, F. M., Sparks, R. S. J., & 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. https://doi.org/10.1016/j.earscirev.2017.04.004

659

660

661

662

Evenstar, Laura A., Hartley, A. J., Stuart, F. M., Mather, A. E., Rice, C. M., & Chong, G. (2009). Multiphase development of the Atacama Planation Surface recorded by cosmogenic 3He exposure ages: Implications for uplift and Cenozoic climate change in Western South America. *Geology*, 37(1), 27–30. https://doi.org/10.1130/G25437A.1

663

664

665

666

Fernández-Mort, A., Riquelme, R., Alonso-Zarza, A. M., Campos, E., Bissig, T., Mpodozis, C., Carretier, S., Herrera, C., Tapia, M., Pizarro, H., & Muñoz, S. (2017). 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. *Mineralium Deposita*, 1–21. https://doi.org/10.1007/s00126-017-0780-2

667

668

669

670

671

Gattacceca, J., Valenzuela, M., Uehara, M., Jull, A. J. T., Giscard, M., Rochette, P., Braucher, R., Suavet, C., Gounelle, M., Morata, D., Munayco, P., Bourot-Denise, M., Bourles, D., & Demory, F. (2011). The densest meteorite collection area in hot deserts: The San Juan meteorite field (Atacama Desert, Chile). *Meteoritics & Planetary Science*, 46(9), 1276–1287. https://doi.org/10.1111/j.1945-5100.2011.01229.x

672

673

674

675

676

Gosse, J. C., & Phillips, F. M. (2001). Terrestrial in situ cosmogenic nuclides: Theory and application. *Quaternary Science Reviews*, 20(14), 1475–1560. https://doi.org/10.1016/S0277-3791(00)00171-2

677

678

679

Granger, D. E., Kirchner, J. W., & Finkel, R. (1996). Spatially Averaged Long-Term Erosion Rates Measured from in Situ-Produced Cosmogenic Nuclides in Alluvial Sediment. *The Journal of Geology*, 104(3), 249–257. https://doi.org/10.1086/629823

680

681

682

Granger, D. E., & Muzikar, P. F. (2001). Dating sediment burial with in situ-produced
683

684

cosmogenic nuclides: Theory, techniques, and limitations. *Earth and Planetary Science Letters*, 188(1–2), 269–281. https://doi.org/16/S0012-821X(01)00309-0

685

686

687

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.

688

689

690

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

691

692

693

694

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

695

696

697

698

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

699

700

701

702

703

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

704

705

706

707

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.

708

709

710

711

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

712

713

714

715

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.

716

717

718

719

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

720

721

722

Kober, F., Ivy-Ochs, S., Schlünegger, 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–
723 120.

724 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.

728 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*, 268(2), 187-191.
https://doi.org/10.1016/j.nimb.2009.09.020

734 Lal, D. (1991). Cosmic ray labeling of erosion surfaces: In-situ nuclide production rates and erosion models. *Earth Planet. Sci. Lett.*, 104, 424-439.

736 Madella, A., Delunel, R., Akçar, N., Schlunegger, F., & Christl, M. (2018). 10Be-inferred paleo-denudation rates imply that the mid-Miocene western central Andes eroded as slowly as today. *Scientific Reports*, 8(1). https://doi.org/10.1038/s41598-018-20681-x

739 Maksaev, V., & Zentilli, M. (1999). Fission track thermochronology of the Domeyko Cordillera, northern Chile; implications for Andean tectonics and porphyry copper metallogenesis.

742 Marinovic, N., & Garcia, M. (n.d.). *Hoja Pampa Unión: Region de Antofagasta escala 1:100.000*.

744 Martin, L. C. P., Blard, P.-H., Balco, G., Lavé, J., Delunel, R., Lifton, N., & Laurent, V. (2017). The CREp program and the ICE-D production rate calibration database: A fully parameterizable and updated online tool to compute cosmic-ray exposure ages. *Quaternary Geochronology*, 38, 25-49. https://doi.org/10.1016/j.quageo.2016.11.006

748 Martinod, J., Regard, V., Riquelme, R., Aguilar, G., Guillaume, B., Carretier, S., Cortés-Aranda, J., Leanni, L., & Hérail, G. (2016). Pleistocene uplift, climate and morphological segmentation of the Northern Chile coasts (24°S-32°S): Insights from cosmogenic 10Be dating of paleoshorelines. *Geomorphology*, 274, 78-91.
https://doi.org/10.1016/j geomorph.2016.09.010

753 Mora, R., Artal, J., Brockway, H., Martinez, E., & Muhr, R. (2004). El Tesoro exotic copper deposit, Antofagasta region, northern Chile. *Society of Economic Geologists, Special Publication*, 11, 187-197.

756 Mortimer, C. (1973). The Cenozoic history of the southern Atacama Desert, Chile. *Journal of the Geological Society, 129*(5), 505-526. https://doi.org/10.1144/gsjgs.129.5.0505

758 Mote, T. I., Becker, T. A., Renne, P., & Brimhall, G. H. (2001). Chronology of Exotic Mineralization at El Salvador, Chile, by 40Ar/39Ar Dating of Copper Wad and Supergene Alunite. *Economic Geology*, 96(2), 351-366.
https://doi.org/10.2113/gsecongeo.96.2.351
762 Mpodozis, C., Marinovic, N., Smoje, I., & Cuitiño, L. (1993). Estudio Geológico-Estructural de la Cordillera de Domeyko entre Sierra Limón Verde y Sierra Mariposas, Región de Antofagasta. *Servicio Nacional de Geología y Minería, Informe Registrado, 4*.

765 Mpodozis, Constantino, & Cornejo, P. (2012). Cenozoic Tectonics and Porphyry Copper Systems of the Chilean Andes. In J. W. Hedenquist, M. Harris, & F. Camus (Eds.), *Geology and Genesis of Major Copper Deposits and Districts of the World: A Tribute to Richard H. Sillitoe* (Vol. 1-Book, Section). Society of Economic Geologists. https://doi.org/10.5382/SP.16.14

770 Münchmeyer, C. (1996). Exotic deposits-products of lateral migration of supergene solutions from porphyry copper deposits. *Soc. Econ. Geol. Spec. Publ.*, 5, 43-58.

772 Niedermann, S. (2002). Cosmic-Ray-Produced Noble Gases in Terrestrial Rocks: Dating Tools for Surface Processes. *Reviews in Mineralogy and Geochemistry*, 47(1), 731-784.
https://doi.org/10.2138/rmg.2002.47.16

775 Nishiizumi, K., Caffee, M. W., Finkel, R. C., Brimhall, G., & Mote, T. (2005). Remnants of a fossil alluvial fan landscape of Miocene age in the Atacama Desert of northern Chile using cosmogenic nuclide exposure age dating. *Earth And Planetary Science Letters*, 237(3-4), 499-507.

779 Nishiizumi, K., Imamura, M., Caffee, M. W., Southon, J. R., Finkel, R. C., & McAninch, J. (2007). Absolute calibration of Be-10 AMS standards. *Nuclear Instruments & Methods In Physics Research Section B-Beam Interactions With Materials And Atoms*, 258(2), 403-413.

783 Oerter, E., Amundson, R., Heimsath, A., Jungers, M., Chong, G., & Renne, P. (2016). Early to Middle Miocene climate in the Atacama Desert of Northern Chile. *Palaeogeography, Palaeoclimatology, Palaeoecology*, 441, 890-900.
https://doi.org/10.1016/j.palaeo.2015.10.038

787 Owen, J. J., Amundson, R., Dietrich, W. E., Nishiizumi, K., Sutter, B., & Chong, G. (2011). The sensitivity of hillslope bedrock erosion to precipitation. *Earth Surface Processes and Landforms*, 36(1), 117-135. https://doi.org/10.1002/esp.2083

790 Palacios, C., Rouxel, O., Reich, M., Cameron, E. M., & Leybourne, M. I. (2011). Pleistocene recycling of copper at a porphyry system, Atacama Desert, Chile: Cu isotope evidence. *Mineralium Deposita*, 46(1), 1-7. https://doi.org/10.1007/s00126-010-0315-6

793 Paskoff, R. (1977). The Quaternary of Chile: The state of research. *Quaternary Research*, 8, 2-31.

795 Perello, J., Muhr, R., Mora, R., Martinez, E., Brockway, H., Swaneck, T., Artal, J., Mpodozis, C., Munchmeyer, C., & Clifford, J. (2010). Wealth creation through exploration in a mature terrain: The case history of the Centinela district, northern Chile porphyry copper belt. *The Challenge of Finding New Mineral Resources: Global Metallogeny, Innovative Exploration, and New Discoveries*, 229-252.

800 Pizarro, H., Rousse, S., Riquelme, R., Veloso, E., Campos, E., González, R., Bissig, T., Carretier, S., Fernández-Mort, A., & Muñoz, S. (2018). The origin of the magnetic
802

803

804

record in Eocene-Miocene coarse-grained sediments deposited in hyper-arid/arid conditions: Examples from the Atacama Desert. *Palaeogeography, Palaeoclimatology, Palaeoecology*. https://doi.org/10.1016/j.palaeo.2018.12.009

805

806

807

808

Placzek, C., Granger, D. E., Matmon, A., Quade, J., & Ryb, U. (2014). Geomorphic process rates in the central Atacama Desert, Chile: Insights from cosmogenic nuclides and implications for the onset of hyperaridity. *American Journal of Science, 314*, 1462–1512. http://dx.doi.org/10.2475/10.2014.03

809

810

811

812

Quang, C. X., Clark, A. H., Lee, J. K. W., & Hawkes, N. (2005). Response of Supergene Processes to Episodic Cenozoic Uplift, Pediment Erosion, and Ignimbrite Eruption in the Porphyry Copper Province of Southern Perú. *Economic Geology*, 100(1), 87–114. https://doi.org/10.2113/100.1.0087

813

814

815

Rech, J. A., Currie, B. S., Michalski, G., & Cowan, A. M. (2006). Neogene climate change and uplift in the Atacama Desert, Chile. *Geology*, 34(9), 761–764. https://doi.org/10.1130/G22444.1

816

817

818

819

820

Rech, J. A., Currie, B. S., Shullenberger, E. D., Dunagan, S. P., Jordan, T. E., Blanco, N., Tomlinson, A. J., Rowe, H. D., & Houston, J. (2010). Evidence for the development of the Andean rain shadow from a Neogene isotopic record in the Atacama Desert, Chile. *Earth and Planetary Science Letters*, 292(3), 371–382. https://doi.org/10.1016/j.epsl.2010.02.004

821

822

823

824

Reich, M., Palacios, C., Vargas, G., Luo, S., Cameron, E. M., Leybourne, M. I., Parada, M. A., Zúñiga, A., & You, C.-F. (2009). Supergene enrichment of copper deposits since the onset of modern hyperaridity in the Atacama Desert, Chile. *Mineralium Deposita*, 44(5), 497. https://doi.org/10.1007/s00126-009-0229-3

825

826

Reich, M., & Vasconcelos, P. M. (2015). Geological and Economic Significance of Supergene Metal Deposits. *Elements*, 11(5), 305–310. https://doi.org/10.2113/gselements.11.5.305

827

828

829

Riquelme, R., Martinod, J., Herail, G., Darrozes, J., & Charrier, R. (2003). A geomorphological approach to determining the Neogene to Recent tectonic deformation in the Coastal Cordillera of northern Chile (Atacama). *Tectonophysics*, 361(3–4), 255.

830

831

832

833

834

Riquelme, Rodrigo, Tapia, M., Campos, E., Mpodozis, C., Carretier, S., González, R., Muñoz, S., Fernández-Mort, A., Sanchez, C., & Marquardt, C. (2018). Supergene and exotic Cu mineralization occur during periods of landscape stability in the Centinela Mining District, Atacama Desert. *Basin Research*, 30(3), 395–425. https://doi.org/10.1111/bre.12258

835

836

837

Ritter, B., Binnie, S. A., Stuart, F. M., Wennrich, V., & Dunai, T. J. (2018). Evidence for multiple Plio-Pleistocene lake episodes in the hyperarid Atacama Desert. *Quaternary Geochronology*, 44, 1–12. https://doi.org/10.1016/j.quageo.2017.11.002

838

839

840

Ritter, B., Stuart, F. M., Binnie, S. A., Gerdes, A., Wennrich, V., & Dunai, T. J. (2018). Neogene fluvial landscape evolution in the hyperarid core of the Atacama Desert. *Scientific Reports*, 8(1), 13952. https://doi.org/10.1038/s41598-018-32339-9

841

Sanchez, C., Brichau, S., Riquelme, R., Carretier, S., Bissig, T., Lopez, C., Mpodozis, C.,
842

843

844

845

Campos, E., Regard, V., Hérail, G., & Marquardt, C. (2018). Exhumation history and timing of supergene copper mineralisation in an arid climate: New thermochronological data from the Centinela District, Atacama, Chile. *Terra Nova, 30*(1), 78–85. https://doi.org/10.1111/ter.12311

846

847

848

849

Sartégou, A., Bourlès, D. L., Blard, P.-H., Braucher, R., Tibari, B., Zimmermann, L., Leanni, L., Aumaître, G., & Keddadouche, K. (2018). Deciphering landscape evolution with karstic networks: A Pyrenean case study. *Quaternary Geochronology, 43*, 12–29. https://doi.org/10.1016/j.quageo.2017.09.005

850

851

Sillitoe, R.H., & McKee, E. H. (1996). Age of Supergene oxidation and enrichment in the chilean porphyry copper province. *Economic Geology, 91*(1), 16.

852

Sillitoe, Richard H. (2010). Porphyry copper systems. *Economic Geology, 105*(1), 3–41.

853

854

Silva, S. L. de. (1989). Altiplano-Puna volcanic complex of the central Andes. *Geology, 17*(12), 1102–1106. https://doi.org/10.1130/0091-7613(1989)017<1102:APVCOT>2.3.CO;2

855

856

857

Strudley, M. W., & Murray, A. B. (2007). Sensitivity analysis of pediment development through numerical simulation and selected geospatial query. *Geomorphology, 88*(3), 329–351. https://doi.org/10.1016/j geomorph.2006.12.008

858

859

860

Suarez, M., & Bell, C. M. (1987). Upper Triassic to Lower Cretaceous continental and coastal saline lake evaporites in the Atacama region of northern Chile. *Geological Magazine, 124*(5), 467–475.

861

862

863

864

Tapia, M., Riquelme, R., Marquardt, C., Mpodozis, C., & Mora, R. (2012). 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, Antofagasta*.

865

866

Team, R. C. (2015). R Foundation for Statistical Computing; Vienna, Austria: 2014. *R: A Language and Environment for Statistical Computing*, 2013.

867

868

869

Tomlinson, A. J., & Blanco, N. (1997). Structural evolution and displacement history of the West Fault System, Precordillera, Chile: Part 2, postmineral history. *Congreso Geológico Chileno, 8*, 1878–1882.

870

871

872

Val, P., & Hoke, G. D. (2016). A practical tool for examining paleoerosion rates from sedimentary deposits using cosmogenic radionuclides: Examples from hypothetical scenarios and data. *Geochemistry, Geophysics, Geosystems, 17*(12), 5078–5088.

873

874

875

Vermeesch, P., Balco, G., Blard, P.-H., Dunai, T. J., Kober, F., Niedermann, S., Shuster, D. L., Strasky, S., Stuart, F. M., & Wieler, R. (2015). Interlaboratory comparison of cosmogenic 21Ne in quartz. *Quaternary Geochronology, 26*, 20–28.

876

877

878

879

880

Wang, F., Michalski, G., Seo, J.-H., Granger, D. E., Lifton, N., & Caffee, M. (2015). Beryllium-10 concentrations in the hyper-arid soils in the Atacama Desert, Chile: Implications for arid soil formation rates and El Niño driven changes in Pliocene precipitation. *Geochimica et Cosmochimica Acta, 160*, 227–242. https://doi.org/10.1016/j.gca.2015.03.008
881 Zimmermann, L., Blard, P. H., Burnard, P., Medynski, S., Pik, R., & Puchol, N. (2012). A new
882 single vacuum furnace design for cosmogenic 3He dating. *Geostandards and*
883 *Geoanalytical Research, 36*(2), 121–129.

884 **7 Tables**

885 **Table 1.** Cosmogenic production schemes, derived from Granger and Muzikar (2001, GR), Braucher et
886 al. (2011, BH and BR), Heisinger et al. (2002; 2002, labelled H and for Neon production in GR, BR, HS).
887 $^{10}$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
888 and Shuster 2009a; Kober et al. 2011).

<table><thead><tr><th></th><th></th><th>GH</th><th>BH</th><th>HS</th><th>BR</th></tr></thead><tbody><tr><td>Spallation</td><td>Λ, Attenuation<br>coefficient (kg/m²)</td><td></td><td>1600</td><td></td><td></td></tr><tr><td rowspan="2">Beryllium-10</td><td>Λ, Attenuation<br>coefficients (kg/m²)</td><td>7380 / 26880 / 43600</td><td>15000 / 43200</td><td>H</td><td>15000 / 43200</td></tr><tr><td>Surface production<br>ratio (%)</td><td>1.8 / 0.4 / 0.4</td><td>0.15 / 0.51</td><td>0.28 / 0.92</td><td>0.15 / 0.51</td></tr><tr><td rowspan="2">Neon-21</td><td><sup>21</sup>Ne to <sup>10</sup>Be spallation<br>production ratio</td><td></td><td>4.12</td><td></td><td></td></tr><tr><td>Λ, Attenuation<br>coefficients (kg/m²)</td><td></td><td>H</td><td></td><td>Idem <sup>10</sup>Be</td></tr><tr><td></td><td>Surface production<br>ratio (%)</td><td></td><td>0 / 3.6</td><td></td><td></td></tr></tbody></table>

889
890
891
892
Table 2. $^{10}$Be concentrations. † denote a sample entirely processed at CEREGE. Final uncertainty is corrected for process blank, AMS standard and AMS systematic error.

<table><thead><tr><th>Sample</th><th>Mass<br>Quartz<br>g</th><th>Carrier<br><sup>9</sup>Be<br>at</th><th>N <sup>10</sup>Be</th><th>Measured<br><sup>10</sup>Be/<sup>9</sup>Be</th><th>uncertainty<br>measure+blank<br>%</th><th>[<sup>10</sup>Be]<br>at/g</th><th>+/-</th></tr></thead><tbody><tr><td colspan="8"><strong>Process<br>blank</strong></td></tr><tr><td>All samples except MIR-10</td><td></td><td>2.39E+19</td><td>38</td><td>4.73E-15</td><td>16.29%</td><td></td><td></td></tr><tr><td>MIR-10 only</td><td></td><td>2.04E+19</td><td>41</td><td>5.41E-15</td><td>15.66%</td><td></td><td></td></tr><tr><td colspan="8"><strong>El Tesoro</strong></td></tr><tr><td>ET-01</td><td>67.35</td><td>2.39E+19</td><td>15</td><td>2.67E-14</td><td>25.86%</td><td>7817</td><td>2021</td></tr><tr><td>ET-02</td><td>62.13</td><td>2.41E+19</td><td>14</td><td>2.44E-14</td><td>31.75%</td><td>7630</td><td>2423</td></tr><tr><td>ET-03</td><td>66.51</td><td>2.39E+19</td><td>18</td><td>1.87E-14</td><td>29.98%</td><td>5030</td><td>1508</td></tr><tr><td>ET-04</td><td>68.28</td><td>2.40E+19</td><td>15</td><td>1.44E-14</td><td>26.70%</td><td>3378</td><td>902</td></tr><tr><td>ET-05</td><td>59.82</td><td>2.41E+19</td><td>54</td><td>2.28E-14</td><td>14.45%</td><td>7288</td><td>1053</td></tr><tr><td>ET-06</td><td>6.19</td><td>2.37E+19</td><td>46</td><td>5.87E-15</td><td>26.77%</td><td>4337</td><td>1161</td></tr><tr><td>ET-07</td><td>13.31</td><td>2.38E+19</td><td>67</td><td>6.45E-15</td><td>12.30%</td><td>3059</td><td>376</td></tr><tr><td>ET-08</td><td>57.76</td><td>2.41E+19</td><td>28</td><td>8.98E-15</td><td>18.95%</td><td>1774</td><td>336</td></tr><tr><td>ET-09</td><td>19.66</td><td>2.38E+19</td><td>44</td><td>7.46E-15</td><td>15.50%</td><td>3298</td><td>511</td></tr><tr><td>AMS blank ET</td><td></td><td></td><td>4</td><td>4.75E-16</td><td></td><td></td><td></td></tr><tr><td colspan="8"><strong>El Mirador</strong></td></tr><tr><td>MIR-01</td><td>12.35</td><td>2.38E+19</td><td>327</td><td>4.00E-14</td><td>5.71%</td><td>68021</td><td>3887</td></tr><tr><td>MIR-04</td><td>2.79</td><td>2.38E+19</td><td>1202</td><td>8.17E-14</td><td>3.26%</td><td>657012</td><td>21426</td></tr><tr><td>MIR-05</td><td>3.70</td><td>2.38E+19</td><td>1176</td><td>1.56E-13</td><td>3.32%</td><td>969755</td><td>32215</td></tr><tr><td>MIR-11</td><td>3.60</td><td>2.39E+19</td><td>30</td><td>5.50E-15</td><td>18.31%</td><td>5133</td><td>940</td></tr><tr><td>AMS blank MIR, except MIR-10</td><td></td><td></td><td>3</td><td>4.23E-16</td><td></td><td></td><td></td></tr><tr><td>MIR-10†</td><td>15.40</td><td>2.04E+19</td><td>71</td><td>8.67E-15</td><td>15.03%</td><td>4320</td><td>2151</td></tr><tr><td>AMS blank MIR-10</td><td></td><td></td><td>5</td><td>5.52E-16</td><td></td><td></td><td></td></tr></tbody></table>

† sample prepared and measured at CEREGE

Final uncertainty is corrected for process blank.

895

896

897

898
<table><caption>899 Table 3. $^{21}$Ne concentrations (cf. Supporting Information)</caption><thead><tr><th>Sample</th><th>Mass<br>Quartz<br>mg</th><th>Extraction<br>temperature<br>(°C)</th><th>[<sup>20</sup>Ne]<br>10<sup>3</sup> at/g</th><th>+/- (1σ)</th><th><sup>21</sup>Ne/<sup>20</sup>Ne</th><th>+/- (1σ)</th><th><sup>22</sup>Ne/<sup>26</sup>Ne</th><th>+/- (1σ)</th><th>Computed<br>cosmogenic<br>[<sup>21</sup>Ne]<br>10<sup>6</sup> at/g</th><th>+/- (1σ)</th><th>Computed<br>cosmogenic<br>[<sup>21</sup>Ne]<br>10<sup>6</sup> at/g</th><th>+/- (1σ)</th></tr></thead><tbody><tr><td colspan="14"><strong>El Tesoro</strong></td></tr><tr><td>ET-01</td><td>173.6</td><td>600</td><td>3.3</td><td>0.1</td><td>0.00274</td><td>0.00010</td><td>0.10095</td><td>0.00289</td><td>&lt; DL</td><td></td><td>&lt; DL</td><td></td></tr><tr><td>ET-02</td><td>173.6</td><td>1400</td><td>51.7</td><td>0.6</td><td>0.00288</td><td>0.00008</td><td>0.10130</td><td>0.00248</td><td>&lt; DL</td><td></td><td></td><td></td></tr><tr><td>ET-03</td><td>149.8</td><td>600</td><td>7.6</td><td>0.2</td><td>0.00314</td><td>0.00008</td><td>0.10201</td><td>0.00224</td><td>1.8</td><td>0.8</td><td>8.8</td><td>5.8</td></tr><tr><td>ET-04</td><td>149.8</td><td>1400</td><td>61</td><td>0.6</td><td>0.00302</td><td>0.00008</td><td>0.10055</td><td>0.00245</td><td>7</td><td>5</td><td>8</td><td>4</td></tr><tr><td>ET-05</td><td>147.7</td><td>1400</td><td>41</td><td>0.5</td><td>0.00309</td><td>0.00010</td><td>0.10191</td><td>0.00305</td><td></td><td></td><td>123</td><td>7</td></tr><tr><td>ET-06</td><td>185.5</td><td>1400</td><td>36.1</td><td>0.5</td><td>0.00629</td><td>0.00017</td><td>0.10181</td><td>0.00287</td><td></td><td></td><td>8</td><td>4</td></tr><tr><td>ET-07</td><td>156.5</td><td>1400</td><td>32</td><td>0.5</td><td>0.00316</td><td>0.00012</td><td>0.10158</td><td>0.00343</td><td></td><td></td><td>7</td><td>5</td></tr><tr><td>ET-08</td><td>105.6</td><td>1400</td><td>7.1</td><td>0.4</td><td>0.00386</td><td>0.00071</td><td>0.10560</td><td>0.01955</td><td></td><td></td><td>8</td><td>4</td></tr><tr><td>ET-09</td><td>185.6</td><td>1400</td><td>31</td><td>0.5</td><td>0.00317</td><td>0.00011</td><td>0.10155</td><td>0.00313</td><td></td><td></td><td>6</td><td>4</td></tr><tr><td>ET-09</td><td>195.4</td><td>1400</td><td>37</td><td>0.5</td><td>0.00307</td><td>0.00009</td><td>0.10070</td><td>0.00273</td><td></td><td></td><td>8</td><td>4</td></tr><tr><td>ET-09</td><td>211.8</td><td>1400</td><td>44.5</td><td>0.6</td><td>0.00296</td><td>0.00008</td><td>0.10115</td><td>0.00243</td><td></td><td></td><td>&lt; DL</td><td></td></tr><tr><td colspan="14"><strong>El Mirador</strong></td></tr><tr><td>MIR-01</td><td>215.1</td><td>1400</td><td>2.8</td><td>0.4</td><td>0.00638</td><td>0.00122</td><td>0.10303</td><td>0.02390</td><td></td><td></td><td>10</td><td>4</td></tr><tr><td>MIR-04</td><td>155.1</td><td>1400</td><td>5.1</td><td>0.4</td><td>0.02602</td><td>0.00335</td><td>0.12506</td><td>0.02047</td><td></td><td></td><td>118</td><td>20</td></tr><tr><td>MIR-05</td><td>145.9</td><td>600</td><td>0.1</td><td>0.1</td><td>0.00845</td><td>0.00298</td><td>0.08614</td><td>0.06122</td><td>0.7</td><td>0.6</td><td>137.7</td><td>8.6</td></tr><tr><td>MIR-05</td><td>145.9</td><td>1400</td><td>38.4</td><td>0.5</td><td>0.00645</td><td>0.00019</td><td>0.10512</td><td>0.00327</td><td>137</td><td>8</td><td></td><td></td></tr><tr><td>MIR-10</td><td>162.3</td><td>600</td><td>3</td><td>0.1</td><td>0.00297</td><td>0.00010</td><td>0.09969</td><td>0.00314</td><td>&lt; DL</td><td></td><td>21.4</td><td>5.5</td></tr><tr><td>MIR-11</td><td>162.3</td><td>1400</td><td>59.3</td><td>0.7</td><td>0.00326</td><td>0.00008</td><td>0.10177</td><td>0.00247</td><td>21.4</td><td>5.5</td><td></td><td></td></tr><tr><td>MIR-11</td><td>79.8</td><td>1400</td><td>4.3</td><td>0.1</td><td>0.00274</td><td>0.00013</td><td>0.09973</td><td>0.00402</td><td></td><td></td><td>&lt; DL</td><td></td></tr></tbody></table>

901

902

903

904

<table><caption>905 Table 4. $^{21}$Ne/$^{10}$Be burial duration (i.e., minimum deposition time, cf. text).</caption><thead><tr><th>Sample</th><th>Depth<br>(m)</th><th><sup>10</sup>Be concentration<br>at/g</th><th><sup>21</sup>Ne conc. x10<sup>6</sup><br>at/g</th><th><sup>21</sup>Ne/<sup>10</sup>Be<br>at/g</th><th>Burial time (source elev<br>=2500m)<br>Ma</th><th>Burial time (source elev<br>=4000m)<br>Ma</th><th>Minimum erosion and<br>sedimentation rate<br>m/myr</th></tr></thead><tbody><tr><td>ET-01</td><td>57</td><td>7985</td><td>3273</td><td>&lt;DL</td><td></td><td></td><td></td></tr><tr><td>ET-02</td><td>59</td><td>7815</td><td>3968</td><td>8.80</td><td>5.80</td><td>1126</td><td>11.2 1.5</td><td>11.2 1.5</td><td>21.7</td></tr><tr><td>ET-03</td><td>63</td><td>5201</td><td>2619</td><td>8</td><td>4</td><td>1538</td><td>11.8 1.4</td><td>11.8 1.5</td><td>19.0</td></tr><tr><td>ET-04</td><td>84</td><td>3545</td><td>1713</td><td>123</td><td>7</td><td>34699</td><td>16.9 1</td><td>17.5 1</td><td>1.0</td></tr><tr><td>ET-05</td><td>105</td><td>7479</td><td>1786</td><td>8</td><td>4</td><td>1070</td><td>11.0 1.1</td><td>11.1 1.1</td><td>15.3</td></tr><tr><td>ET-06</td><td>106</td><td>6156</td><td>7116</td><td>7</td><td>5</td><td>1137</td><td>11.2 2</td><td>11.2 2.1</td><td>17.1</td></tr><tr><td>ET-07</td><td>108</td><td>3907</td><td>1899</td><td>8</td><td>4</td><td>2048</td><td>12.3 1.4</td><td>12.4 1.5</td><td>16.7</td></tr><tr><td>ET-08</td><td>111</td><td>1973</td><td>892</td><td>6</td><td>4</td><td>3042</td><td>13.2 1.6</td><td>13.2 1.6</td><td>22.3</td></tr><tr><td>ET-09</td><td>115</td><td>3873</td><td>1790</td><td>&lt;DL</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>MIR-01</td><td>18</td><td>68021</td><td>6209</td><td>10</td><td>4</td><td>147</td><td>7.0 0.8</td><td>7.1 0.8</td><td>11.9</td></tr><tr><td>MIR-04</td><td>13</td><td>657012</td><td>32335</td><td>118</td><td>20</td><td>180</td><td>6.4 0.2</td><td>7.0 0.3</td><td>1.0</td></tr><tr><td>MIR-05</td><td>12</td><td>969755</td><td>46786</td><td>137.70</td><td>8.60</td><td>142</td><td>5.8 0.1</td><td>6.4 0.1</td><td>0.9</td></tr><tr><td>MIR-11</td><td>45</td><td>4320</td><td>2057</td><td>21.40</td><td>5.50</td><td>4954</td><td>13.9 1.1</td><td>14.1 1.1</td><td>7.1</td></tr><tr><td>MIR-10</td><td>63</td><td>5133</td><td>8383</td><td>&lt;DL</td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

907

908

909
<table><caption>**Table 5.** Summary of information on sedimentation and denudation rates inferred from the analysis presented in this work.</caption><thead><tr><th>Time period</th><th>Sedimentation rate (m/My)</th><th>Source denudation rate (m/My)</th></tr></thead><tbody><tr><td>Present</td><td>&lt;2</td><td>&lt;1</td></tr><tr><td>7 Ma - present</td><td>&lt;2</td><td>&lt;10</td></tr><tr><td>9.5 - 7 Ma</td><td>&lt;2</td><td>&gt;50</td></tr><tr><td>x - 9.5Ma</td><td>&gt;100</td><td>&gt;250</td></tr><tr><td>Deposition of the copper rich layer. Ends sometime between 10 and 14 Ma (= x)</td><td>0.5-5</td><td>&gt;250</td></tr></tbody></table>

## 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.

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 3: Quantification of the erosion (denudation) rates in the northern Chilean Atacama Desert (18-30°S) over decades shown in red (suspended sediment gauging), over millennia shown in blue or green (cosmogenic isotopes to measure either local or catchment-averaged denudation rates) or over million years shown in purple (incision of geological surfaces) (extracted from the database of Carretier et al., 2018). The box width reflects the number of data (indicated inside or under the box).

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.
941 Figure 5: Sedimentary columns of the Tesoro Central and Mirador open-pit mines (adapted from Fernández-Mort et al., 2017) with the sampling depths, gravel formation names and sedimentary details. The 9.52 ± 0.02 Ma age for the Artola ignimbrite has been measured by Riquelme et al. (2018).

944
945 Figure 6: 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).

949
950 Figure 7: Bipyramid automorph quartz found in MIR13-01 reworked from 9.5 Ma-old ignimbrite (Riquelme et al. 2018)

952
953 Figure 8. Production vs. depth (log scale) for the different schemes (left: ¹⁰Be; right: ²¹Ne). The different colored lines represent the different production rate schemes tested: GH, BH, HS and BR (see Table 1 for further details).

956
957 Figure 9: Reference inversion for the El Tesoro mining pit (BR). (A) The color corresponds to the χ² value: light yellow to brown, where a darker color is a better fit; the grey areas correspond to the tested scenario leading to improbable χ² 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.

963
964 Figure 10. Cosmogenic isotope concentration (reference inversion) according to depth (Tesoro Central), A. for ¹⁰Be and B. for ²¹Ne. For both figures, the light colors correspond to every Monte Carlo scenario tested; the bold lines represent the best χ² scenario for ¹⁰Be only, ²¹Ne 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.

969
970 Figure 11. Best χ² 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 (¹⁰Be and ²¹Ne, logarithmic χ²-scale). The points indicate the best χ² from the inversions, the trend is drawn as lines.

973
974 Figure 12. χ² 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 ¹⁰Be (top, linear χ²-scale) or ²¹Ne and ¹⁰Be data (bottom, logarithmic χ²-scale). The latter shows that low values are reached for denudation rates higher than ~40 m/Ma.

978
979 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.
981 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).

984

985

# 9 Data Sharing and Data Accessibility

986 The data that support the findings of this study are found in the core of the paper, except the code
987 IMIS, openly available in GitHub at https://github.com/regard-vincent/IMIS.
<table><thead><tr><th></th><th></th><th>GH</th><th>BH</th><th>HS</th><th>BR</th></tr></thead><tbody><tr><td></td><td>Spallation<br>Λ, Attenuation<br>coefficient (kg/m²)</td><td></td><td>1600</td><td></td><td></td></tr><tr><td rowspan="2">Beryllium-10</td><td>Λ, Attenuation<br>coefficients (kg/m²)</td><td>7380 / 26880 / 43600</td><td>15000 / 43200</td><td>H</td><td>15000 / 43200</td></tr><tr><td>Surface production<br>ratio (%)</td><td>1.8 / 0.4 / 0.4</td><td>0.15 / 0.51</td><td>0.28 / 0.92</td><td>0.15 / 0.51</td></tr><tr><td></td><td><sup>21</sup>Ne to <sup>10</sup>Be spallation<br>production ratio</td><td></td><td>4.12</td><td></td><td></td></tr><tr><td rowspan="2">Neon-21</td><td>Λ, Attenuation<br>coefficients (kg/m²)</td><td></td><td>H</td><td></td><td>Idem <sup>10</sup>Be</td></tr><tr><td>Surface production<br>ratio (%)</td><td></td><td>0 / 3.6</td><td></td><td></td></tr></tbody></table>
<table><thead><tr><th>Sample</th><th>Mass<br>Quartz<br>g</th><th>Carrier<br><sup>9</sup>Be<br>at</th><th>N<br><sup>10</sup>Be</th><th>Measured<br><sup>10</sup>Be/<sup>9</sup>Be</th><th>uncertainty<br>measure+blank<br>%</th><th>[<sup>10</sup>Be]<br>at/g</th><th>+/-</th></tr></thead><tbody><tr><td colspan="8"><strong>Process<br>blank</strong></td></tr><tr><td>All samples except MIR-10</td><td></td><td>2.39E+19</td><td>38</td><td>4.73E-15</td><td>16.29%</td><td></td><td></td></tr><tr><td>MIR-10 only</td><td></td><td>2.04E+19</td><td>41</td><td>5.41E-15</td><td>15.66%</td><td></td><td></td></tr><tr><td colspan="8"><strong>El Tesoro</strong></td></tr><tr><td>ET-01</td><td>67.35</td><td>2.39E+19</td><td>15</td><td>2.67E-14</td><td>25.86%</td><td>7817</td><td>2021</td></tr><tr><td>ET-02</td><td>62.13</td><td>2.41E+19</td><td>14</td><td>2.44E-14</td><td>31.75%</td><td>7630</td><td>2423</td></tr><tr><td>ET-03</td><td>66.51</td><td>2.39E+19</td><td>18</td><td>1.87E-14</td><td>29.98%</td><td>5030</td><td>1508</td></tr><tr><td>ET-04</td><td>68.28</td><td>2.40E+19</td><td>15</td><td>1.44E-14</td><td>26.70%</td><td>3378</td><td>902</td></tr><tr><td>ET-05</td><td>59.82</td><td>2.41E+19</td><td>54</td><td>2.28E-14</td><td>14.45%</td><td>7288</td><td>1053</td></tr><tr><td>ET-06</td><td>6.19</td><td>2.37E+19</td><td>46</td><td>5.87E-15</td><td>26.77%</td><td>4337</td><td>1161</td></tr><tr><td>ET-07</td><td>13.31</td><td>2.38E+19</td><td>67</td><td>6.45E-15</td><td>12.30%</td><td>3059</td><td>376</td></tr><tr><td>ET-08</td><td>57.76</td><td>2.41E+19</td><td>28</td><td>8.98E-15</td><td>18.95%</td><td>1774</td><td>336</td></tr><tr><td>ET-09</td><td>19.66</td><td>2.38E+19</td><td>44</td><td>7.46E-15</td><td>15.50%</td><td>3298</td><td>511</td></tr><tr><td>AMS blank ET</td><td></td><td></td><td>4</td><td>4.75E-16</td><td></td><td></td><td></td></tr><tr><td colspan="8"><strong>El Mirador</strong></td></tr><tr><td>MIR-01</td><td>12.35</td><td>2.38E+19</td><td>327</td><td>4.00E-14</td><td>5.71%</td><td>68021</td><td>3887</td></tr><tr><td>MIR-04</td><td>2.79</td><td>2.38E+19</td><td>1202</td><td>8.17E-14</td><td>3.26%</td><td>657012</td><td>21426</td></tr><tr><td>MIR-05</td><td>3.70</td><td>2.38E+19</td><td>1176</td><td>1.56E-13</td><td>3.32%</td><td>969755</td><td>32215</td></tr><tr><td>MIR-11</td><td>3.60</td><td>2.39E+19</td><td>30</td><td>5.50E-15</td><td>18.31%</td><td>5133</td><td>940</td></tr><tr><td>AMS blank MIR, except MIR-10</td><td></td><td></td><td>3</td><td>4.23E-16</td><td></td><td></td><td></td></tr><tr><td>MIR-10†</td><td>15.40</td><td>2.04E+19</td><td>71</td><td>8.67E-15</td><td>15.03%</td><td>4320</td><td>2151</td></tr><tr><td>AMS blank MIR-10</td><td></td><td></td><td>5</td><td>5.52E-16</td><td></td><td></td><td></td></tr></tbody></table>

† sample prepared and measured at CEREGE

Final uncertainty is corrected for process blank.
<table><thead><tr><th>Sample</th><th>Mass<br>Quartz<br>mg</th><th>Extraction<br>temperature<br>(°C)</th><th>[<sup>20</sup>Ne]<br>10<sup>9</sup> at/g</th><th>+/- (1σ)</th><th><sup>21</sup>Ne/<sup>20</sup>Ne</th><th>+/- (1σ)</th><th><sup>22</sup>Ne/<sup>20</sup>Ne</th><th>+/- (1σ)</th><th>Computed<br>cosmogenic<br>[<sup>21</sup>Ne]<br>10<sup>6</sup> at/g</th><th>+/- (1σ)</th><th>Computed<br>cosmogenic<br>[<sup>21</sup>Ne]<br>10<sup>6</sup> at/g</th><th>+/- (1σ)</th></tr></thead><tbody><tr><td colspan="14"><strong>El Tesoro</strong></td></tr><tr><td>ET-01</td><td>173.6</td><td>600</td><td>3.3</td><td>0.1</td><td>0.00274</td><td>0.00010</td><td>0.10095</td><td>0.00289</td><td>&lt; DL</td><td></td><td>&lt; DL</td><td></td></tr><tr><td></td><td>173.6</td><td>1400</td><td>51.7</td><td>0.6</td><td>0.00288</td><td>0.00008</td><td>0.10130</td><td>0.00248</td><td>&lt; DL</td><td></td><td></td><td></td></tr><tr><td></td><td>149.8</td><td>600</td><td>7.6</td><td>0.2</td><td>0.00314</td><td>0.00008</td><td>0.10201</td><td>0.00224</td><td>1.8</td><td>0.8</td><td>8.8</td><td>5.8</td></tr><tr><td>ET-02</td><td>149.8</td><td>1400</td><td>61</td><td>0.6</td><td>0.00302</td><td>0.00008</td><td>0.10055</td><td>0.00245</td><td>7</td><td>5</td><td>8</td><td>4</td></tr><tr><td>ET-03</td><td>147.7</td><td>1400</td><td>41</td><td>0.5</td><td>0.00309</td><td>0.00010</td><td>0.10191</td><td>0.00305</td><td></td><td></td><td>123</td><td>7</td></tr><tr><td>ET-04</td><td>185.5</td><td>1400</td><td>36.1</td><td>0.5</td><td>0.00629</td><td>0.00017</td><td>0.10181</td><td>0.00287</td><td></td><td></td><td>8</td><td>4</td></tr><tr><td>ET-05</td><td>156.5</td><td>1400</td><td>32</td><td>0.5</td><td>0.00316</td><td>0.00012</td><td>0.10158</td><td>0.00343</td><td></td><td></td><td>7</td><td>5</td></tr><tr><td>ET-06</td><td>105.6</td><td>1400</td><td>7.1</td><td>0.4</td><td>0.00386</td><td>0.00071</td><td>0.10560</td><td>0.01955</td><td></td><td></td><td>8</td><td>4</td></tr><tr><td>ET-07</td><td>185.6</td><td>1400</td><td>31</td><td>0.5</td><td>0.00317</td><td>0.00011</td><td>0.10155</td><td>0.00313</td><td></td><td></td><td>8</td><td>4</td></tr><tr><td>ET-08</td><td>195.4</td><td>1400</td><td>37</td><td>0.5</td><td>0.00307</td><td>0.00009</td><td>0.10070</td><td>0.00273</td><td></td><td></td><td>6</td><td>4</td></tr><tr><td>ET-09</td><td>211.8</td><td>1400</td><td>44.5</td><td>0.6</td><td>0.00296</td><td>0.00008</td><td>0.10115</td><td>0.00243</td><td></td><td></td><td>&lt; DL</td><td></td></tr><tr><td colspan="14"><strong>El Mirador</strong></td></tr><tr><td>MIR-01</td><td>215.1</td><td>1400</td><td>2.8</td><td>0.4</td><td>0.00638</td><td>0.00122</td><td>0.10303</td><td>0.02390</td><td></td><td></td><td>10</td><td>4</td></tr><tr><td>MIR-04</td><td>155.1</td><td>1400</td><td>5.1</td><td>0.4</td><td>0.02602</td><td>0.00335</td><td>0.12506</td><td>0.02047</td><td></td><td></td><td>118</td><td>20</td></tr><tr><td>MIR-05</td><td>145.9</td><td>600</td><td>0.1</td><td>0.1</td><td>0.00845</td><td>0.00298</td><td>0.08614</td><td>0.06122</td><td>0.7</td><td>0.6</td><td>137.7</td><td>8.6</td></tr><tr><td></td><td>145.9</td><td>1400</td><td>38.4</td><td>0.5</td><td>0.00645</td><td>0.00019</td><td>0.10512</td><td>0.00327</td><td>137</td><td>8</td><td></td><td></td></tr><tr><td>MIR-10</td><td>162.3</td><td>600</td><td>3</td><td>0.1</td><td>0.00297</td><td>0.00010</td><td>0.09969</td><td>0.00314</td><td>&lt; DL</td><td></td><td>21.4</td><td>5.5</td></tr><tr><td>MIR-11</td><td>162.3</td><td>1400</td><td>59.3</td><td>0.7</td><td>0.00326</td><td>0.00008</td><td>0.10177</td><td>0.00247</td><td>21.4</td><td>5.5</td><td></td><td></td></tr><tr><td></td><td>79.8</td><td>1400</td><td>4.3</td><td>0.1</td><td>0.00274</td><td>0.00013</td><td>0.09973</td><td>0.00402</td><td></td><td></td><td>&lt; DL</td><td></td></tr></tbody></table>
<table><thead><tr><th rowspan="2">Sample</th><th rowspan="2">Depth (m)</th><th colspan="2"><sup>10</sup>Be concentration</th><th colspan="2"><sup>21</sup>Ne conc. x10<sup>6</sup></th><th rowspan="2"><sup>21</sup>Ne/<sup>10</sup>Be</th><th colspan="2">Burial time (source elev =2500m)</th><th colspan="2">Burial time (source elev =4000m)</th><th rowspan="2">Minimum erosion and sedimentation rate m/myr</th></tr><tr><th>at/g</th><th>+/-</th><th>at/g</th><th>+/-</th><th>Ma</th><th>+/-</th><th>Ma</th><th>+/-</th></tr></thead><tbody><tr><td>ET-01</td><td>57</td><td>7985</td><td>3273</td><td>&lt;DL</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>ET-02</td><td>59</td><td>7815</td><td>3968</td><td>8.80</td><td>5.80</td><td>1126</td><td>11.2</td><td>1.5</td><td>11.2</td><td>1.5</td><td>21.7</td></tr><tr><td>ET-03</td><td>63</td><td>5201</td><td>2619</td><td>8</td><td>4</td><td>1538</td><td>11.8</td><td>1.4</td><td>11.8</td><td>1.5</td><td>19.0</td></tr><tr><td>ET-04</td><td>84</td><td>3545</td><td>1713</td><td>123</td><td>7</td><td>34699</td><td>16.9</td><td>1</td><td>17.5</td><td>1</td><td>1.0</td></tr><tr><td>ET-05</td><td>105</td><td>7479</td><td>1786</td><td>8</td><td>4</td><td>1070</td><td>11.0</td><td>1.1</td><td>11.1</td><td>1.1</td><td>15.3</td></tr><tr><td>ET-06</td><td>106</td><td>6156</td><td>7116</td><td>7</td><td>5</td><td>1137</td><td>11.2</td><td>2</td><td>11.2</td><td>2.1</td><td>17.1</td></tr><tr><td>ET-07</td><td>108</td><td>3907</td><td>1899</td><td>8</td><td>4</td><td>2048</td><td>12.3</td><td>1.4</td><td>12.4</td><td>1.5</td><td>16.7</td></tr><tr><td>ET-08</td><td>111</td><td>1973</td><td>892</td><td>6</td><td>4</td><td>3042</td><td>13.2</td><td>1.6</td><td>13.2</td><td>1.6</td><td>22.3</td></tr><tr><td>ET-09</td><td>115</td><td>3873</td><td>1790</td><td>&lt;DL</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>MIR-01</td><td>18</td><td>68021</td><td>6209</td><td>10</td><td>4</td><td>147</td><td>7.0</td><td>0.8</td><td>7.1</td><td>0.8</td><td>11.9</td></tr><tr><td>MIR-04</td><td>13</td><td>657012</td><td>32335</td><td>118</td><td>20</td><td>180</td><td>6.4</td><td>0.2</td><td>7.0</td><td>0.3</td><td>1.0</td></tr><tr><td>MIR-05</td><td>12</td><td>969755</td><td>46786</td><td>137.70</td><td>8.60</td><td>142</td><td>5.8</td><td>0.1</td><td>6.4</td><td>0.1</td><td>0.9</td></tr><tr><td>MIR-11</td><td>45</td><td>4320</td><td>2057</td><td>21.40</td><td>5.50</td><td>4954</td><td>13.9</td><td>1.1</td><td>14.1</td><td>1.1</td><td>7.1</td></tr><tr><td>MIR-10</td><td>63</td><td>5133</td><td>8383</td><td>&lt;DL</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>
<table><thead><tr><th>Time period</th><th>Sedimentation rate (m/My)</th><th>Source denudation rate (m/My)</th></tr></thead><tbody><tr><td>Present</td><td>&lt;2</td><td>&lt;1</td></tr><tr><td>7 Ma - present</td><td>&lt;2</td><td>&lt;10</td></tr><tr><td>9.5 - 7 Ma</td><td>&lt;2</td><td>&gt;50</td></tr><tr><td>x - 9.5Ma</td><td>&gt;100</td><td>&gt;250</td></tr><tr><td>Deposition of the copper rich layer.</td><td></td><td></td></tr><tr><td>Ends sometime between 10 and 14 Ma</td><td></td><td></td></tr><tr><td>(= x)</td><td>0.5-5</td><td>&gt;250</td></tr></tbody></table>
<figure><img src="image_3.png" /><figcaption>Sanchez et al. Fig 1</figcaption></figure>
<figure><img src="image_4.png" /></figure>

Sanchez et al. Figure 2
<figure><img src="image_5.png" /><figcaption>Sanchez et al. Figure 3</figcaption></figure>
<figure><img src="image_6.png" /><figcaption>Tesoro Central</figcaption></figure>

<figure><img src="image_7.png" /><figcaption>Mirador</figcaption></figure>

<figure><img src="image_8.png" /></figure>

1

E

<figure><img src="image_9.png" /></figure>

2

<figure><img src="image_10.png" /></figure>

Sampling path

<figure><img src="image_11.png" /></figure>

Exotic-Cu ore deposit enriched layer

<figure><img src="image_12.png" /></figure>

Picture views

<figure><img src="image_13.png" /></figure>

Exotic-Cu ore deposit

<figure><img src="image_14.png" /></figure>

Contact between gravels and Cu supergene deposit

<figure><img src="image_15.png" /></figure>

Samples

ET13-05 Sample names

FOR REVIEW PURPOSES ONLY
**Tesoro Central**
160 m

Tesoro gravels

<figure><img src="image_16.png" /></figure>

ET13-02
ET13-01
ET13-03

ET13-04

ET13-05
ET13-06
ET13-07
ET13-08
ET13-09

Tesoro Central and Mirador open-pit sequence

<figure><img src="image_17.png" /></figure>

Ungraded breccias

<figure><img src="image_18.png" /></figure>

Cobble- to pebble-size well-
stratified conglomerates

<figure><img src="image_19.png" /></figure>

Siltstones

<figure><img src="image_20.png" /></figure>

Sandstones

<figure><img src="image_21.png" /></figure>

Ignimbrite

<figure><img src="image_22.png" /></figure>

Sandy limestones

<figure><img src="image_23.png" /></figure>

Exotic-Cu orebodies

<figure><img src="image_24.png" /></figure>

Porphyry copper

<figure><img src="image_25.png" /></figure>

Low-angle trough-cross bedding

<figure><img src="image_26.png" /></figure>

Sample location

<figure><img src="image_27.png" /></figure>

Sand sample collected
in exotic-Cu layer

**Mirador**
70 m

70 m

Arrieros gravels

MIR13-05
MIR13-04
MIR13-01
9.52 ± 0.02 Ma

?

MIR13-11

MIR13-10

<figure><img src="image_28.png" /></figure>
<figure><img src="image_29.png" /><figcaption>Sanchez et al. Figure 6</figcaption></figure>
<figure><img src="image_30.png" /></figure>

Bipyramid automorph quartz found in MIR13-01 reworked from 9.5 Ma-old ignimbrite (Riquelme et al., 2018)

111x80mm (72 x 72 DPI)
<figure><img src="image_31.png" /><figcaption>Sanchez et al. Figure 8</figcaption></figure>
<figure><img src="image_32.png" /></figure>

<figure><img src="image_33.png" /></figure>
<figure><img src="image_34.png" /></figure>

<figure><img src="image_35.png" /><figcaption>Sanchez et al. Figure 10</figcaption></figure>
<figure><img src="image_36.png" /><figcaption>Sanchez et al. Figure 11</figcaption></figure>
<figure><img src="image_37.png" /></figure>

Sanchez et al. Figure 12
<figure><img src="image_38.png" /><figcaption>Sanchez et al. Figure 13</figcaption></figure>

FOR REVIEW PURPOSES ONLY
# Supporting information

## Contents

<table><tr><td>1</td><td>Sample preparation</td><td>1</td></tr><tr><td>2</td><td>Reference inversion</td><td>3</td></tr><tr><td>2.1</td><td>Reference inversion, production scheme BH</td><td>4</td></tr><tr><td>2.2</td><td>Reference inversion, production scheme BR</td><td>7</td></tr><tr><td>2.3</td><td>Reference inversion, production scheme HS</td><td>9</td></tr><tr><td>3</td><td>Density in reference experiment</td><td>11</td></tr><tr><td>4</td><td>Reference inversion for el Mirador pit</td><td>13</td></tr><tr><td>5</td><td>Test inversion for Davis et al. 2014 data</td><td>15</td></tr></table>

## 1 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 non-magnetic 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 (Arnold et al., 2010). 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% (Arnold et al., 2010), and a chemical blank measurement. In all computations, a ¹⁰Be half-life of (1.387 ± 0.01) x 10⁶ years was used (Chmeleff et al., 2010; Korschinek et al., 2010).

The second quartz aliquots were used for measuring the cosmogenic ²¹Ne 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 (Zimmermann et al., 2012) 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 ²¹Ne concentration (²¹Ne_cos) was performed following:

$$^{21}\text{Ne}_{\text{cos}} = R_c \times ^{20}\text{Ne}_{\text{atm}} \times (R_m - R_a)/(R_c - R_a), \text{ (equation 2)}$$

where ²⁰Ne_m (at.g⁻¹) is the measured ²⁰Ne concentration in quartz, R_c = 0.8 the cosmogenic ²¹Ne/²⁰Ne production ratio (Niedermann, 2002); R_m is the measured ²¹Ne/²⁰Ne ratio and Ra = 0.002905 is the atmospheric ²¹Ne/²⁰Ne ratio (Honda et al., 2015) (Figure A1).

<figure><img src="image_39.png" /><figcaption>Figure A1: 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 Honda et al., 2015) and assuming a ²²Ne/²¹Ne production ratio of 1.1 (Niedermann, 2002).</figcaption></figure>
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).

## 2 Sensitivity analysis

<table><caption>Table 1. Main parameters tested for a sensitivity analysis</caption><thead><tr><th>Parameter tested</th><th>Reference</th><th>Result tested</th><th>Reference value</th><th>Value when varying the tested parameter</th><th>Reference</th></tr></thead><tbody><tr><td rowspan="2">Production scheme</td><td rowspan="2">BR</td><td>Copper rich layer age</td><td>10-14 Ma</td><td>Not significantly different</td><td>Appendix</td></tr><tr><td>Denudation rate before 9.5 Ma</td><td>> 250</td><td>Not significantly different</td><td>Figure 11</td></tr><tr><td rowspan="2">Density of the sediments</td><td rowspan="2">2300 kg/m3</td><td>Copper rich layer age</td><td>10-14 Ma</td><td>Not significantly different, larger range for lower densities (10-15Ma for 2100 kg/m3, 10-16 Ma for 1900 kg/m3)</td><td>Appendix</td></tr><tr><td>χ<sup>2</sup></td><td>10-20</td><td>Not significantly different for higher densities. Increases for lower densities up to ~60 (worse fit), except for the GR production scheme</td><td>Figure A12</td></tr></tbody></table>

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

## 3 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 $10^{-5}-5 \times 10^{-4}$ 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.
<figure><img src="image_40.png" /></figure>

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 ¹⁰Be and ²¹Ne, ¹⁰Be only and ²¹Ne only, respectively.

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 ¹⁰Be 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 ²¹Ne production scheme: H and S stands for Heisinger et al. (2002) and R for Braucher et al. (2011); ¹⁰Be production SLHL is set to 4.15 at/g/a (Martin et al., 2017), and the ²¹Ne/¹⁰Be ratio is 4.12 (Balco & Shuster, 2009; Kober et al., 2011). The reference is model BR.

## 3.1 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 ¹⁰Be. For ²¹Ne, the attenuation scheme follows the definition by Heisinger et al. (2002).
<figure><img src="image_41.png" /></figure>

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 ¹⁰Be and ²¹Ne, ¹⁰Be and ²¹Ne only, respectively.

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 ¹⁰Be only and ¹⁰Be/²¹Ne 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><img src="image_42.png" /></figure>

Figure A4. Cosmogenic isotope concentration (reference inversion) in the Tesoro Central open pit using the BH parameters, according to depth; the top figure shows ¹⁰Be and the bottom shows ²¹Ne. For both figures, the light colors correspond to every Monte Carlo scenario tested; the bold lines represent the best χ² scenario for ¹⁰Be only, ²¹Ne 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><img src="image_43.png" /></figure>

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 ¹⁰Be and ²¹Ne, ¹⁰Be and ²¹Ne 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).

## 3.2 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 ¹⁰Be. For ²¹Ne, the attenuation scheme follows the definition by Heisinger et al. (2002).

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 ¹⁰Be 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.
<figure><img src="image_44.png" /></figure>

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 ¹⁰Be and ²¹Ne, ¹⁰Be and ²¹Ne only, respectively.
<figure><img src="image_45.png" /></figure>

Figure A7. Cosmogenic isotope concentration (reference inversion, GR production scheme) in the Tesoro Central open pit using the GR 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 $\chi^2$ 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><img src="image_46.png" /></figure>

Figure A8. Graph representing the sedimentation rate (m/a) vs. time in Ma (reference inversion) with GR production parameters. The black, blue and red lines correspond to the best fit scenario for both ¹⁰Be and ²¹Ne, ¹⁰Be and ²¹Ne only, respectively.

## 3.3 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 Heisinger et al. (2002) 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 ¹⁰Be 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.
<figure><img src="image_47.png" /></figure>

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 ¹⁰Be and ²¹Ne, ¹⁰Be and ²¹Ne only, respectively.
<figure><img src="image_48.png" /></figure>

Figure A10. Cosmogenic isotope concentration (reference inversion) in the Tesoro Central open pit using the HS parameters, according to depth; the top figure shows ¹⁰Be and the bottom shows ²¹Ne. For both figures, the light colors correspond to every Monte Carlo scenario tested; the bold lines represent the best χ² scenario for ¹⁰Be only, ²¹Ne 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><img src="image_49.png" /></figure>

Figure A11. Graph representing the sedimentation rate (m/a) vs. time in Ma (reference inversion) with HS production parameters. The black, blue and red lines correspond to the best fit scenario for both ¹⁰Be and ²¹Ne, ¹⁰Be and ²¹Ne only, respectively.

# 4 Density in the reference experiment

This section shows experiments based on the El Tesoro reference inversion (density of 2500 kg/m³) but with variable sedimentary layer densities of 1900, 2100, and 2500 kg/m³. If the sediment filling the basin were denser, X² would be lower (from ~60 for 1900 kg/m³ to 20 for 2200-2500 kg/m³, 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.
<figure><img src="image_50.png" /></figure>

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/m³.

<figure><img src="image_51.png" /></figure>

Figure A13. 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 1900 kg/m³. The black, blue and red lines correspond to the best fit scenario for both ¹⁰Be and ²¹Ne, ¹⁰Be and ²¹Ne only, respectively.
<figure><img src="image_52.png" /></figure>

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/m³. The black, blue and red lines correspond to the best fit scenario for both ¹⁰Be and ²¹Ne, ¹⁰Be and ²¹Ne only, respectively.
<figure><img src="image_53.png" /></figure>

Figure A15. Age of the sediments (Ma) in function of the depth (m) in the Tesoro Mine (reference model for the BR production scheme), with sediment density of 2500 kg/m³. The black, blue and red lines correspond to the best fit scenario for both ¹⁰Be and ²¹Ne, ¹⁰Be and ²¹Ne only, respectively.

# 5 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 ²¹Ne 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 ¹⁰Be and ²¹Ne, ¹⁰Be and ²¹Ne only, respectively. Figure A16).

The agreement with the data is not satisfactory (Figure A17). The ¹⁰Be 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.

<figure><img src="image_54.png" /></figure>

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 ¹⁰Be and ²¹Ne, ¹⁰Be and ²¹Ne only, respectively.
<figure><img src="image_55.png" /></figure>

Figure A17. Cosmogenic isotope concentration (reference inversion) in the Mirador open pit using BR according to depth; the top figure shows ¹⁰Be and the bottom shows ²¹Ne. For both figures, the light colors correspond to every Monte Carlo scenario tested; the bold lines represent the best χ² scenario for ¹⁰Be only, ²¹Ne 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><img src="image_56.png" /></figure>

Figure A18. Model on the sediment age (Ma) in function of the depth (m) in the Mirador Mine, using the BR production parameters, and focused on the post-10 Ma period. The black, blue and red lines correspond to the best fit scenario for both ¹⁰Be and ²¹Ne, ¹⁰Be and ²¹Ne only, respectively.

# 6 Test inversion for Davis et al.'s data (2014)

No significant change in $\chi^2$ 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 ¹⁰Be and ²⁶Al 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.
<figure><img src="image_57.png" /></figure>

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.
<figure><img src="image_58.png" /></figure>

Figure A20. Cosmogenic isotope concentration (reference inversion) for the dataset provided by Davis et al. (2014) using GH parameters, according to depth; the top figure shows $^{10}$Be and the bottom shows $^{26}$Al. For both figures, the light colors correspond to every Monte Carlo scenario tested; the bold lines represent the best $\chi^2$ scenario for $^{10}$Be only, $^{26}$Al only and for both nuclides in blue, green and black, respectively. The circles and associated horizontal lines indicate the measured concentrations and their related uncertainties.

# 7 References

ARNOLD, M., MERCHEL, S., BOURLÈS, D.L., BRAUCHER, R., BENEDETTI, L., FINKEL, R.C., AUMAÎTRE, G., GOTTDANG, A. & KLEIN, M. 2010. The French accelerator mass spectrometry facility ASTER: Improved performance and developments. *Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms* **268**(11), 1954–1959.
BALCO, G. 2017. Production rate calculations for cosmic-ray-muon-produced 10 Be and 26 Al benchmarked against geological calibration data. *Quaternary Geochronology* **39**, 150–173.

BALCO, G. & SHUSTER, D.L. 2009. Production rate of cosmogenic 21Ne in quartz estimated from 10Be, 26Al, and 21Ne concentrations in slowly eroding Antarctic bedrock surfaces. *Earth and Planetary Science Letters* **281**(1–2), 48–58.

BRAUCHER, R., MERCHEL, S., BORGOMANO, J. & BOURLÄ¨S, D.L. 2011. Production of cosmogenic radionuclides at great depth: A multi element approach. *Earth and Planetary Science Letters* **309**(1–2), 1–9.

BRAUCHER, R., GUILLOU, V., BOURLÈS, D.L., ARNOLD, M., AUMAÎTRE, G., KEDDADOUCHE, K. & NOTTOLI, E. 2015. Preparation of ASTER in-house 10Be/9Be standard solutions. *Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms* **361**, 335–340.

BROWN, E.T., EDMOND, J.M., RAISBECK, G.M., YIOU, F., KURZ, M.D. & BROOK, E.J. 1991. Examination of surface exposure ages of Antarctic moraines using in situ produced 10Be and 26Al. *Geochimica et Cosmochimica Acta* **55**(8), 2269.

CHMELEFF, J., VON BLANCKENBURG, F., KOSSERT, K. & JAKOB, D. 2010. Determination of the Be-10 half-life by multicollector ICP-MS and liquid scintillation counting. *Nuclear Instruments & Methods In Physics Research Section B-Beam Interactions With Materials And Atoms* **268**(2), 192–199.

DAVIS, M., MATMON, A., PLACZEK, C.J., MCINTOSH, W., ROOD, D.H. & QUADE, J. 2014. Cosmogenic nuclides in buried sediments from the hyperarid Atacama Desert, Chile. *Quaternary Geochronology* **19**, 117–126.

DE SILVA, S. 1989. Altiplano-Puna volcanic complex of the central Andes. *Geology* **17**(12), 1102–1106.

DUNAI, T.J., LOPEZ, G.A.G. & JUEZ-LARRE, J. 2005. Oligocene-Miocene age of aridity in the Atacama Desert revealed by exposure dating of erosion-sensitive landforms. *Geology* **33**(4), 321–324.

GRANGER, D.E. & MUZIKAR, P.F. 2001. Dating sediment burial with in situ-produced cosmogenic nuclides: theory, techniques, and limitations. *Earth and Planetary Science Letters* **188**(1–2), 269–281.

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**(3–4), 357–369.

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.

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.

KORSCHINEK, G., BERGMAIER, A., FAESTERMANN, T., GERSTMANN, U.C., KNIE, K., RUGEL, G., WALLNER, A., DILLMANN, I., DOLLINGER, G. & VON GOSTOMSKI, C.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* **268**(2), 187–191.

MARTIN, L.C.P., BLARD, P.-H., BALCO, G., LAVÉ, J., DELUNEL, R., LIFTON, N. & LAURENT, V. 2017. The CREp program and the ICE-D production rate calibration database: A fully parameterizable and updated online tool to compute cosmic-ray exposure ages. *Quaternary Geochronology* **38**, 25–49.

NIEDERMANN, S. 2002. Cosmic-Ray-Produced Noble Gases in Terrestrial Rocks: Dating Tools for Surface Processes. *Reviews in Mineralogy and Geochemistry* **47**(1), 731–784.

NISHIIZUMI, K., IMAMURA, M., CAFFEE, M.W., SOUTHON, J.R., FINKEL, R.C. & MCANINCH, J. 2007. Absolute calibration of Be-10 AMS standards. *Nuclear Instruments & Methods In Physics Research Section B-Beam Interactions With Materials And Atoms* **258**(2), 403–413.

RIQUELME, R., TAPIA, M., CAMPOS, E., MODOZIS, C., CARRETIER, S., GONZÁLEZ, R., MUÑOZ, S., FERNÁNDEZ-MORT, A., SANCHEZ, C. & MARQUARDT, C. 2018. Supergene and exotic Cu mineralization occur during periods of landscape stability in the Centinela Mining District, Atacama Desert. *Basin Research* **30**(3), 395–425.

SARTÉGOU, A., BOURLÈS, D.L., BLARD, P.-H., BRAUCHER, R., TIBARI, B., ZIMMERMANN, L., LEANNI, L., AUMAÎTRE, G. & KEDDADOUCHE, K. 2018. Deciphering landscape evolution with karstic networks: A Pyrenean case study. *Quaternary Geochronology* **43**, 12–29.

VERMEESCH, P., BALCO, G., BLARD, P.-H., DUNAI, T.J., KOBER, F., NIEDERMANN, S., SHUSTER, D.L., STRASKY, S., STUART, F.M., WIELER, R. & ZIMMERMANN, L. 2015. Interlaboratory comparison of cosmogenic 21 Ne in quartz. *Quaternary Geochronology* **26**, 20–28.

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 Geoanalytical Research* **36**(2), 121–129.