S Brichau

P Reyes

C Gautheron

M J Hernández

F Michaud

M Leisen

A Vacherat

M Saillard

J N Proust

P O'sullivan

First timing constraints on the Ecuadorian Coastal Cordillera exhumation: Geodynamic implications

Keywords: Ecuadorian Coastal Cordillera, Carnegie Ridge, Subduction, Forearc domain

In this study, we provide the first detrital apatite (U-Th-Sm)/He (AHe) and zircon U-Pb ages to establish a detailed short-term chronology of the burial and exhumation history, which occurred in the Coastal Cordillera along the forearc domain of Ecuador. First, our results allowed us to define a range of maximum deposition ages for the Angostura Formation from 9.6 ± 0.2 Ma to 11.5 ± 0.6 Ma, which records high enough temperatures to partially reset AHe ages. QTQt thermal inverse modeling of the AHe dataset reveals three main periods of J o u r n a l P r e -p r o o f exhumation along the Costal Cordillera at ~2 Ma, ~5-6 Ma and ~8-10 Ma, independent of the sample geographic locations. We discuss the origin of these periods of exhumation in relation to the geodynamic frame. The oldest exhumation event, at ~8-10 Ma, evidenced locally along fault systems, could be related to overriding plate kinematic changes or early arrival of Carnegie Ridge. The intermediate exhumation period, at ~5-6 Ma, could be explained by a later arrival of the Carnegie Ridge or to the subduction of an along-strike positive relief of the ridge. Later, subduction of sea-floor asperities could be responsible for heterogeneous uplift of the Coastal Cordillera during the Pleistocene (~2 Ma) that induced exhumation as supported by our models. These results are corroborated by previous studies and demonstrate that AHe data are sensitive enough to provide reliable constraints in sedimentary domains.

INTRODUCTION

Ongoing uplift and relief building on the overriding plate along active subduction margins frequently depends on the stability of certain parameters such as slab pull, mantle dynamics and absolute plate motion (Lallemand et al., 2005;[START_REF] Schellart | Evolution and diversity of subduction zones controlled by slab width[END_REF]Cerpa and Arcay, 2020), penetration and anchored of the slab into the lower mantle [START_REF] Faccenna | Initiation of the Andean orogeny by lower mantle subduction[END_REF], inherited structures of the upper plate margin (Audin et al., 2008), subduction of seafloor reliefs (Zeumann and Hampel, 2016;[START_REF] Morell | Seamount, ridge, and transform subduction in southern Central America[END_REF][START_REF] Collot | Subducted oceanic relief locks the shallow megathrust in central Ecuador[END_REF] and subduction-erosion versus subduction-accretion behaviors (Clift and Vannucchi, 2004), among others. These parameters are supposed to control the mechanical coupling between plates as well as the relief generation related to forearc deformation [START_REF] Noda | Forearc basins: Types, geometries, and relationships to subduction zone dynamics[END_REF]. Building J o u r n a l P r e -p r o o f topography and climate change, exert a feedback control on the sediment input into the subduction channel [START_REF] Horton | Sedimentary record of Andean mountain building[END_REF][START_REF] Saillard | From the seismic cycle to long-term deformation: linking seismic coupling and Quaternary coastal geomorphology along the Andean megathrust[END_REF], which is thought to have a strong impact on seismogenic zone behavior [START_REF] Collot | The South Ecuador subduction channel: Evidence for a dynamic mega-shear zone from 2D fine-scale seismic reflection imaging and implications for material transfer[END_REF][START_REF] Saffer | Hydrogeology and mechanics of subduction zone forearcs: Fluid flow and pore pressure[END_REF]Heuret et al., 2012, Behr andBecker, 2018).

Since many processes can be responsible for the evolution of the subduction systems and the stress accumulation at the plate interface, it is of prime importance to define the timing and how relief generation occurs in the forearc domain to decipher which are the processes involved in a specific area.

Along the South American Pacific margin, terrigenous sediment contribution is controlled by the erosion of the Andean orogen, which induces a significant supply of material to the forearc basin (Witt et al., 2017;Fig. 1). In the Ecuadorian forearc, the uplifting of the Coastal Cordillera, which culminates at about 800 m above the sea level (Fig. 1), has hindered the sediment pathways from the Andes, thereby enhancing sediment starvation in the trench. Andean sourced sediments are currently rerouted by the northern Esmeraldas river system [START_REF] Collot | The Esmeraldas Canyon: A Helpful Marker of the Pliocene-Pleistocene Tectonic Deformation of the North Ecuador-Southwest Colombia Convergent Margin[END_REF], and by the southern Guayas river into the Gulf of Guayaquil (Deniaud et al., 1999), crossing through the ends of the Coastal Cordillera (Fig. 1).

Consequently, at present-day, the resulting sedimentary fluxes supplied into the subduction trench correspond with the modern river patterns draining the western slope of the Coastal Cordillera. This morphotectonic effect implies a sediment starved-trench, which is expected to modify the shear stress along the plate interface and to promote strong impacts on the tectonic and seismogenic plate interface coupling (Cloos and Shreve, 1988;[START_REF] Ruff | Do trench sediments affect great earthquake occurrence in subduction zones?[END_REF][START_REF] Heuret | Relation between subduction megathrust earthquakes, trench sediment thickness and upper plate strain[END_REF][START_REF] Scholl | Great (≥ Mw8. 0) megathrust earthquakes and the subduction of excess sediment and bathymetrically smooth seafloor[END_REF].

The timing and amount of uplift throughout the Ecuadorian Coastal Cordillera, with the exception of the specific littoral [START_REF] J O U R N A L P R E -P R O O F Pedoja | Plio-Quaternary uplift of the Manta Peninsula and La Plata Island and the subduction of the Carnegie Ridge, central coast of Ecuador[END_REF] and offshore [START_REF] Michaud | Quaternary sedimentation and active faulting along the Ecuadorian shelf: preliminary results of the ATACAMES Cruise[END_REF][START_REF] Proust | Subduction of seafloor asperities revealed by a detailed stratigraphic analysis of the active margin shelf sediments of Central Ecuador[END_REF][START_REF] Collot | The Esmeraldas Canyon: A Helpful Marker of the Pliocene-Pleistocene Tectonic Deformation of the North Ecuador-Southwest Colombia Convergent Margin[END_REF]Hernández et al., 2020) areas, is poorly known (Reyes, J o u r n a l P r e -p r o o f phase of high rates of rock uplift and exhumation around ~13-15 Ma in the Eastern Cordillera of Ecuador [START_REF] Spikings | Along-strike variations in the thermal and tectonic response of the continental Ecuadorian Andes to the collision with heterogeneous oceanic crust[END_REF]Villagómez and Spikings, 2012). They attribute this vertical displacement and exhumation to the collision and subduction of the Carnegie Ridge. For the same period, Chiaradia et al. (2020) speculate that the subduction of the Carnegie Ridge could have affected magmatism geochemistry as crustal thickness increase. However, for Collot et al. (2009), morpho-tectonics evidences argue for the beginning of Carnegie Ridge subduction at ~5 Ma. The structural segmentation of the offshore forearc domain during the early Pliocene (~5.2 Ma) is tentatively associated with the arrival of the Carnegie Ridge into the subduction zone and the creation of a mosaic of middle-late Pleistocene depocenters that alternate with uplifted zones along the shelf that are proposed to record the subduction of the topographically irregular Carnegie Ridge (Hernández et al., 2020). At the same time, incision of the Esmeraldas canyon (Fig. 1) began to form in response to a boost of the forearc uplift (~5.3 Ma ago) that is temporally correlated with the Carnegie Ridge subduction following by two deep incisions providing evidences for uplift episodes in the mid-Pliocene and early Pleistocene times [START_REF] Collot | The Esmeraldas Canyon: A Helpful Marker of the Pliocene-Pleistocene Tectonic Deformation of the North Ecuador-Southwest Colombia Convergent Margin[END_REF].

Morphostructural Segmentation

The coastal forearc system of the Ecuadorian margin is organized into four morphotectonic zones including: the western border of the Andes, the adjacent onshore platform (currently the emerged ca. 170 km wide coastal region), the offshore platform (ca. 50 km wide), and the continental slope that has been partially modified by the Carnegie Ridge subduction at the trench (Collot et al., 2009;Fig. 1). The onshore forearc shows three major morphostructural domains: the piedmont basin (coastal plain) characterized by alluvial fan development, the Coastal Cordillera, in front of the Carnegie Ridge (Fig. 1) bounding the active western margin, and the Gulf of Guayaquil to the south. The northern part of the J o u r n a l P r e -p r o o f coastal plain persists until the Colombian margin. Morphometric analysis along river profiles suggest that the Coastal Cordillera is divided into five distinct structural blocks or domains [START_REF] J O U R N A L P R E -P R O O F Reyes | Relative Quantification of Costal Cordillera (Ecuador) Uplift: Preliminary Results from Quantitative Geomorphology[END_REF][START_REF] Reyes | Évolution du relief le long des marges actives: Etude de la déformation Plio-Quaternaire de la cordillère côtière d'Equateur[END_REF][START_REF] Reyes | Quantitative morphometric analysis of the Jama River profile in a tectonically active margin (Northwestern Ecuador)[END_REF].

Stratigraphy of the fore-arc basins

The Miocene sedimentary fill of the onshore coastal forearc is emplaced over preexistent sedimentary basins during the Cretaceous and the Paleogene filling cycles. The Upper Cretaceous cycle is characterized by high-lithified volcaniclastics, turbidites (Cayo Formation) and bedded chert sequences deposited over a thickened oceanic crust (basalts and gabbros of the Piñon Formation) of middle-late Cretaceous age [START_REF] Reynaud | Oceanic plateau and island arcs of Southwestern Ecuador: their place in the geodynamic evolution of northwestern South America[END_REF]Luzieux et al., 2006;[START_REF] Vallejo | Backbone of the Americas: Shallow Subduction, Plateau Uplift, and Ridge and Terrane Collision[END_REF]. The Paleogene cycle comprises a basal siliciclastic turbiditic sequence giving rise upsection to coarsening upward calcareous and pelitic siliceous series with some volcanoclasts. The Miocene sediments have been dated by biostratigraphy (Benítez, 1995;Deniaud, 2000;Ordóñez et al. 2006;Cantalamessa et al., 2007) and fill local depressions separated by basement structural highs (Fig. 3). A ca. 2500 m thick pelitic and diatomaceous stratigraphic succession is deposited in all the basins (stratigraphic level named as Dos Bocas, Viche, Villingota Formations). This is overlain by the shallow marine 100-500 m thick sandy Angostura Formation (Bristow and Hoffstetter, 1977;Benitez, 1995), including volcanoclastic coarse-grained turbidites indicative of a deeper marine environment [START_REF] Reyes | Évolution du relief le long des marges actives: Etude de la déformation Plio-Quaternaire de la cordillère côtière d'Equateur[END_REF]. The proposed age of the Angostura Formation ranges from ~9 Ma to ~15 Ma (Benítez, 1995;Deniaud, 2000;Ordóñez et al. 2006;Cantalamessa et al., 2007), but may be diachronous. The transition to the overlying late Miocene Ónzole Formation is often conformable and gradual (Deniaud, 2000), with locally, planar discontinuity (Cantalamessa et al., 2007). The Ónzole Formation comprises 300 to 700 m of thick bluish grey siltstones, of marine platform environment (Deniaud, 2000), passing upward with an unconformable and J o u r n a l P r e -p r o o f erosional contact (Di Celma et al., 2010) to 100 to 400 m of shallow water marine coarse sandstones, conglomerates and volcaniclastics of the Pliocene to Lower Pleistocene Borbón Formation [START_REF] Reyes | Évolution du relief le long des marges actives: Etude de la déformation Plio-Quaternaire de la cordillère côtière d'Equateur[END_REF]Fig. 3).

Inversion of the fore-arc basins

Regional stratigraphy provides a first constraint to estimate the amount of exhumation and growth of the Coastal Cordillera (Fig. 2). Marine sediments of Mio-Pliocene age, deposited in onshore forearc domain, dominate some of the highest areas (i.e. ~ 600 m) of the Coastal Cordillera (Benítez, 1995;Deniaud, 2000) and reveal a late Neogene uplift (Evans and Whittaker, 1982). The northern Borbón basin area (Esmeralda region) is exposed along Mache-Chindul mountain range, which is separated from the central-south Manabí basin by the EW-trending Canandé fault (Fig. 2). This southward dipping fault reveals, at first, a normal displacement during the early-middle Miocene followed by a compressional activity during the Pliocene, controlling the relative uplift of the Borbón basin (Hernández et al., 2020). The 100 to 500 m thick massive turbidites of the Angostura Formation are preserved in the two basins. The 300 to 700 m thick Ónzole and 100 to 400 m thick Borbón Formations bury the Angostura Formation in this domain [START_REF] Reyes | Évolution du relief le long des marges actives: Etude de la déformation Plio-Quaternaire de la cordillère côtière d'Equateur[END_REF]. To the South, the eastward dipping NE-SW-trending Jama fault system [START_REF] Reyes | Évolution du relief le long des marges actives: Etude de la déformation Plio-Quaternaire de la cordillère côtière d'Equateur[END_REF][START_REF] Reyes | Quantitative morphometric analysis of the Jama River profile in a tectonically active margin (Northwestern Ecuador)[END_REF] bounds the Jama massif (block) cored by oceanic plateau affinities Cretaceous rocks (pillow basalts, dolerites and gabbro) of the Piñón Formation (Bristow and Hoffstetter, 1977) and surrounded by the Angostura Formation (Fig. 2). Along this fault, a normal displacement during the early-middle Miocene is followed by compression, underlined by an anticlinal during the Pliocene (Hernández et al., 2020). In the central Manabí basin, the flat-topped Pichincha-Portoviejo 400 m-high consists of sub-horizontally uplifted strata of the Borbón Formation.

J o u r n a l P r e -p r o o f

The NNE-SSW trending sub-vertical Jipijapa fault, controls the Jipijapa massif (block, Fig. 2), which juxtaposes the Cretaceous rocks of the basement against the Miocene sediments of the Dos Bocas Formation [START_REF] Reyes | Évolution du relief le long des marges actives: Etude de la déformation Plio-Quaternaire de la cordillère côtière d'Equateur[END_REF]. In the southern Manabi basin, the WNW-ESE trending south-verging Chongón-Colonche fault raises the basement-cored Chongón-Colonche massif (block) that separates the Manabí basin from the southern Progreso basin (Fig. 2) [START_REF] Reyes | Évolution du relief le long des marges actives: Etude de la déformation Plio-Quaternaire de la cordillère côtière d'Equateur[END_REF].

Andes cooling events and sediment provenance in the fore-arc basins

Detrital sediments and volcaniclastic material deposited in the forearc basin are largely delivered from the Ecuadorian Andes (Deniaud, 2000). The collision-accretion history of the Ecuadorian Andes initiated in the Lower Cretaceous with the accretion of tectonometamorphic terranes (Litherland et al., 1994) along the Eastern Cordillera and continued in the Upper Cretaceous with the accretion of the oceanic terranes in the Western Cordillera [START_REF] Goossens | Chemical composition and age determination of tholeitic rocks in the basic Cretaceous Complex, Ecuador[END_REF][START_REF] Feininger | Cretaceous and Paleogene history of coastal Ecuador[END_REF]Lebrat et al. 1987;[START_REF] Reynaud | Oceanic plateau and island arcs of Southwestern Ecuador: their place in the geodynamic evolution of northwestern South America[END_REF]Kerr et al., 2002;Luzieux et al., 2006;[START_REF] Vallejo | Backbone of the Americas: Shallow Subduction, Plateau Uplift, and Ridge and Terrane Collision[END_REF][START_REF] Jaillard | Stratigraphy of the Late Cretaceous-Paleogene deposits of the Western Cordillera of Central Ecuador: Geodynamic implications[END_REF]2009). These accreted terranes recorded important magmatic (both granitoid and mafic) and volcanic events from Triassic to Holocene times (Cochrane et al., 2014;[START_REF] Spikings | The geological history of northwestern South America: from Pangaea to the early collision of the Caribbean Large Igneous Province (290-75 Ma)[END_REF].

The main recognized zircon U-Pb age peaks are ~234-207 Ma, ~182-141 Ma, and ~40-5 Ma in the Northern part of Ecuadorian Andes (from 1°N to 3°S). In the southern part of the Ecuadorian Andes, detrital zircon ages from the Cenozoic forearc basins in SW Ecuador suggest that the Western Cordillera was already uplifted in the Paleocene (Witt et al., 2017).

Fission tracks analysis from this basement revealed two main periods of regional scale cooling at ~13 and ~9 Ma [START_REF] Spikings | Thermochronology of allochthonous terranes in Ecuador: Unravelling the accretionary and post-accretionary history of the Northern Andes[END_REF], close to the age of the Angostura Formation sediments, followed by a rapid cooling and exhumation at ~5.5-0 Ma [START_REF] Spikings | Syn-and post-accretionary cooling history of the Ecuadorian Andes constrained by their in-situ and detrital thermochronometric record[END_REF].

METHODOLOGY AND RESULTS

J o u r n a l P r e -p r o o f

Method

To constrain the timing of the Coastal Cordillera uplift, the strategy of sampling has been defined according to geographic localizations along the coast, appropriate lithology to maximize the probability to obtain apatite crystals and stratigraphic level buried enough to record if not fully at least partially resetted apatite (U-Th-Sm)/He (AHe) thermochronometer.

Accordingly, the more adapted lithology in a sedimentary rock environment remains the sandstones. Therefore, we attempted to collect 13 samples in the Angostura Formation all along the Costal Cordillera (Fig. 2, Table 1), based on facies criteria since the sandstone Angostura Formation is framed by two formations more fine and clayey (below the pelitic Dos Bocas Formation and above the Ónzole Formation described as a siltstone). Furthermore, in order to avoid mistakes about the stratigraphic level in which samples have been collected, we performed U-Pb dating on zircon to determine the youngest detrital age.

Apatite and zircon grains were separated using standard heavy liquid and magnetic separation techniques between GeoAzur (Nice, France) and Geosciences Environnement Toulouse (GET, France).

In most samples, over 100 grains of zircon were selected for in situ U-Pb dating using LA-ICPMS at GeoSep Services (Moscow, Idaho, USA) and Geosciences Environnement Toulouse (GET, France) following the procedure detailed by [START_REF] Prudhomme | Western thrusting and uplift in northern Central Andes (western Peruvian margin)[END_REF] and [START_REF] Kahou | First U-Pb LA-ICP-MS in situ dating of supergene copper mineralization: Case study in the Chuquicamata mining district, Atacama Desert, Chile[END_REF]. Analytical procedure and data are reported in supplementary section under the Table A Apatite grains were carefully selected for AHe age dating, then each crystal was measured and loaded in platinum (Pt) capsules for He, U, Th, and Sm measurements at GEOPS laboratory (Orsay, France), following the procedure described by [START_REF] Fillon | Oligocene-Miocene burial and exhumation of the Southern Pyrenean foreland quantified by low-temperature thermochronology[END_REF].

The alpha ejection factor (F T ) and sphere equivalent radius (Rs) were calculated for each J o u r n a l P r e -p r o o f crystal using Qt_F T software [START_REF] J O U R N A L P R E -P R O O F Gautheron | A Monte Carlo approach to diffusion applied to noble gas/helium thermochronology[END_REF]Ketcham et al., 2011).

Between three to ten replicates per sample, depending of the availability of quality apatite grains (inclusions and cracks free, avoiding broken grains, width over 60 µm), have been carried out and the results are reported in Table 2.

To be able to interpret and extract the thermal history of our samples, we perform inversion modeling of the AHe data set using the software QTQt [START_REF] Gallagher | Transdimensional inverse thermal history modelling for quantitative thermochronology[END_REF]. The inverse modeling was performed using the kinetic models for helium diffusion in apatite crystals from [START_REF] Gautheron | Effect of alpha-damage annealing on apatite (U-Th)/He thermochronology[END_REF] that takes into account the He production and diffusion in damaged apatite structure. Radiation damage accumulation depends on production during U-Th and Sm decay and annealing that is a function of the crystal size chemistry and temperature. The apatite grain size (Rs), He, U, Th and Sm content for each crystal of the sample were used for the inversion (Table 2). The inversion procedure uses a Bayesian "Markov chain Monte Carlo" algorithm to determine the best time-temperature path reproducing our data through a large number (200,000) of randomly tested solutions (see [START_REF] Gallagher | Transdimensional inverse thermal history modelling for quantitative thermochronology[END_REF] for detailed modeling procedure). In order to fully exploit the thermal history information contained in partially annealed samples and therefore improve the resolution on the modeling, QTQt is able to model the pre-depositional thermal history of the apatite grains.

The models were performed for a parameter space (time t and temperature T) at 40 ± 40 Ma and 70 ± 70 °C (red box) and a constraint at surface temperature during sediment deposition time were used (15 to 5 Ma or 15 to 9 Ma, small black box). This large time box before sediment deposition time allows the model to explore pre-depositional history and was fixed to allow Cenozoic history. For one sample (13ECC04), where the modeling did not converge correctly, we added a constraint at 70 ± 10 Ma, 60 ± 60 °C (long before the deposition time and older than the oldest AHe age) to take into account all possible scenarios J o u r n a l P r e -p r o o f before deposit. Samples 13ECC12A and 12B were modeled together as they are considered to be a single sedimentary unit because of their close geographical location. The final model is represented by a set of time-temperature histories for which we included the expected model (weighted mean model, black line) and the maximum likelihood model (best data fitting model, orange line). In addition, the predicted AHe ages for the expected model and the maximum likelihood models obtained by QTQt are reported as a function of the observed (measured) AHe ages.

Results

Zircon U-Pb dating

Since the purpose of zircon U-Pb dating was to constrain maximum depositional ages, the number of analyses per sample is less critical than for a detailed provenance study.

However, we attempted to date over 100 grains to fit the recommendation of [START_REF] Vermeesch | How many grains are needed for a provenance study? Earth Planet[END_REF]. Only in samples 12ECC05 and 18BCB02, the number of analyses is below 100 (at 29 and 95, respectively), due to the small amount of zircon available.

It is usual to filter the data set to apply a 10 to 20 % discordance cutoff with the aim of avoiding data related to Pb loss processes. Yet, in the case of young ages (e.g. <100 Ma), this discordant filter is not valid due to the difficulty of determining a reliable 206 Pb/ 207 Pb or 207 Pb/ 235 Pb ratios [START_REF] Gehrels | Detrital Zircon U-Pb Geochronology: Current Methods and New Opportunities[END_REF]. In our study, we collected samples in a Miocene stratigraphic level, implying that the ages obtained are mostly young and therefore discordancy filter is not applicable since most of the ages are highly discordance for ages below 50 Ma (as shown in Table A. 1 and Fig. A.1).

In all samples, the main age populations are Cenozoic and Cretaceous with a small Precambrian contribution and sometimes, a slight additional input from Paleozoic to Triassic sources (Table A.2).

J o u r n a l P r e -p r o o f

To represent the data set for each sample and to be able to compare the youngest peak ages, we have represented the results under an age-distribution diagram that includes the error of each analysis [START_REF] Gehrels | Detrital Zircon U-Pb Geochronology: Current Methods and New Opportunities[END_REF]. We choose, for better visibility of the youngest age peaks, to show only the results for ages younger than 40 Ma. To define the youngest detrital zircon (YDZ) age, several methods have been defined over the last decade. According to Dickinson and Gehrels (2009) and [START_REF] Coutts | Assessment of widely used methods to derive depositional ages from detrital zircon populations[END_REF], the best way to determine the YDZ age is to calculate the weighted mean age of the youngest cluster of three or more grain ages overlapping in age at 2σ uncertainty. However, for [START_REF] Spencer | Strategies towards statistically robust interpretations of in situ U-Pb zircon geochronology[END_REF][START_REF] Copeland | On the use of geochronology of detrital grains in determining the time of deposition of clastic sedimentary strata[END_REF], the weighted mean can only be used if the zircons are from a single population, such as volcanic eruption or rapidly emplaced pluton. Therefore, [START_REF] Spencer | Strategies towards statistically robust interpretations of in situ U-Pb zircon geochronology[END_REF] recommend practicing multiple analyses on the youngest zircon grain to assure the validity of the analysis, to check the lack of correlation between U and Th content versus age to rule out potential Pbloss, and to add chemical or isotopic data such as Hf to ensure that the weighted mean has been defined on a single forming-zircon event. For [START_REF] Copeland | On the use of geochronology of detrital grains in determining the time of deposition of clastic sedimentary strata[END_REF], the best estimate will be to use the youngest single concordant grain and not an averaging of data. We did not perform additional analyses to ensure the single population origin of our zircons since the purpose of these analyses is only to verify if our samples have been collected in the correct formation (Angostura). However, no correlation between U or Th and ages has been observed (Table A.2) and we followed the recommendation of [START_REF] Copeland | On the use of geochronology of detrital grains in determining the time of deposition of clastic sedimentary strata[END_REF] and reported in table 3 the YDZ and the youngest concordant (discordancy below 15%) single grain (YCSG) ages. All results are similar within errors, except for sample 18BCB02 which presents low U content and almost no concordant ages (only two data are below 15% of discordancy, see Table A .2).

Since the purpose of these analyses is only to verify if our samples have been collected in the correct formation (Angostura with youngest depositional age estimated at ~9 Ma) and owing to the fact that YDZ and YCSG ages are similar within errors and the ages are young with J o u r n a l P r e -p r o o f low U content, it seems more appropriate here to use the YDZ ages which have been obtained, as the age-distribution diagrams, using the routine available from www.geo.arizona.edu/alc (Table 3 and Fig. 4).

Two samples, 12ECC05 and 12ECC07, show clearly younger peak ages than expected for Angostura Formation (YDZ ages at 7.0 ± 0.3 Ma and 7.1 ± 0.2 Ma, respectively), indicating that they belong to the Ónzole Formation, from its lowest level. The YDZ age for sample 18BCB02 seems to be slightly older than 12ECC05 and 07, at 7.7 ± 0.1 Ma, and maybe close to the limit between Angostura and Ónzole Formation. For all the other samples, the YDZ range from 9.6 ± 0.2 Ma to 11.5 ± 0.5 Ma corresponding to the range of the depositional ages of the Angostura Formation (Benítez, 1995;Deniaud, 2000;Ordóñez et al. 2006;Cantalamessa et al., 2007). The diagrams of relative age probability between actual and 40 Ma (Fig. 4) display, for most of the samples, a well defined young peak age corresponding to the YDZ ages of the Angostura (for samples 13ECC12A,12B,07,08,34,and 16MCC06) and Ónzole Formations (12ECC05, 07 and 18BCB02). For samples 13ECC04, 06, 11 and 16MCC03, we can note that the age distributions reveal a different pattern without a welldefined young peak age and even a more smoothed distribution (especially for samples 13ECC04 and 06; Fig. 4). This feature could be related to the fact that all these sandstones have been collected nearby faults (Jama, Tanigüe, Jipijapa/Cascol faults), which could locally disturb the sediment supply and distribution. Indeed, it has been demonstrated that fault activities can lead to the formation of structurally-controlled depocentres, a heterogeneous pattern of accommodation space and sediment thickness (Brandes et al., 2007;Serck and Braathen, 2018). Furthermore, synsedimentary faulting can as well disturb the sediment gravity flow dynamics implying variation of the erosion behavior on short distances (less than 500 m; [START_REF] Pochat | Impact of synsedimentary metre-scale normal fault scarps on sediment gravity flow dynamics: An example from the Grès d'Annot Formation, SE France[END_REF]. In the Coastal Cordillera of Ecuador, little is J o u r n a l P r e -p r o o f known about the fault activity and motion range. Therefore, to define the real impact of these faults on the sediment dynamics, a more detailed field study would be necessary.

Apatite (U-Th-Sm)/He dating

All samples display AHe ages ranging from 1.4 ± 0.1 to 53.9 ± 4.3 Ma, and most of them are younger than the YDZ defined by U-Pb dating or even younger than the youngest depositional ages defined by biostratigraphy (Table 2, 3 and Fig. 5) for the Angostura Formation at 9.1 Ma by Cantalamessa et al. (2007). Our samples have been collected all along the Coastal Cordillera, over a distance of 300 km. Each sample displays AHe ages younger than the depositional age indicate that they have been at least partially reset. This general pattern of partial reset over such a distance is reasonably explained by post-deposition burial, reaching the partial retention zone (PRZ), which range from 40 to 120°C, depending on each apatite diffusion coefficient and apatite crystal size [START_REF] Shuster | The influence of natural radiation damage on helium diffusion kinetics in apatite[END_REF][START_REF] Flowers | Apatite (U-Th)/He thermochronometry using a radiation damage accumulation and annealing model[END_REF][START_REF] Gautheron | Effect of alpha-damage annealing on apatite (U-Th)/He thermochronology[END_REF]Shuster & Farley, 2009;Brown et al., 2013;Ault et al., 2019). In addition, some apatite crystals present higher AHe ages than the depositional age for low effective Uranium content (eU = U + 0.243Th + 0.0046Sm) (Fig. 5). Those older AHe ages with low eU content reflect the impact of alpha implantation by neighboring minerals [START_REF] J O U R N A L P R E -P R O O F Spiegel | Apatite (U-Th-Sm)/He thermochronology of rapidely cooled samples: The effect of He implantation[END_REF][START_REF] Gautheron | Accounting for long alpha-particle stopping distances in (U-Th-Sm)/He geochronology: 3D modeling of diffusion, zoning, implantation, and abrasion[END_REF][START_REF] Murray | Effects of U-Th-rich grain boundary phases on apatite helium ages[END_REF], especially when eU values are below 20 ppm and ages over 10 Ma, following the exact pattern of the implantation model prediction defined by [START_REF] Murray | Effects of U-Th-rich grain boundary phases on apatite helium ages[END_REF]. In addition, the presence of defects or inclusions (fluid or solid) [START_REF] Recanati | Helium trapping in apatite damage: Insights from (U-Th-Sm)/He dating of different granitoid lithologies[END_REF]Zeitler et al., 2017;[START_REF] Mcdannell | Screening apatites for (U-Th)/He thermochronometry via continuous ramped heating: He age components and implications for age dispersion[END_REF] and the chemical composition of apatite (Gautheron et al. 2013) could impact the AHe system. The impact of radiation damage levels, approximated by the eU content of each dated grains [START_REF] Gautheron | Effect of alpha-damage annealing on apatite (U-Th)/He thermochronology[END_REF][START_REF] Flowers | Apatite (U-Th)/He thermochronometry using a radiation damage accumulation and annealing model[END_REF], and the cumulative time span of the sample at a very low temperature above the PRZ (see Ault et al., 2019 for a review) could play a J o u r n a l P r e -p r o o f significant role if the sediments are not reset at enough temperature (>80-100°C). However, most of our data show only a slight apparent AHe age vs eU (or Th/U) correlation or AHe age vs apatite size (Rs) and all the older AHe ages obtained seem to reflect alpha-implantation impact (as identified in Fig. 5, A.2 and A.3).

Modeling

Obtained thermal histories and observed versus predicted AHe ages are reported in Figure 6 and replaced along the topographic map of the Ecuadorian Coastal Cordillera.

Modeling used only AHe data that are not affected by alpha-implantation (>10-12 Ma).

Depositional constraints have been set up, taking into account our YDZ ages defined by U-Pb dating. However, since the YDZ age could be older than the known stratigraphic position [START_REF] Copeland | On the use of geochronology of detrital grains in determining the time of deposition of clastic sedimentary strata[END_REF] we decided to use the youngest deposition age defined by biostratigraphy (Benítez, 1995;Deniaud, 2000;Ordóñez et al. 2006;Cantalamessa et al., 2007).

Consequently, for samples 12ECC05, 12ECC07 and 18BCB02 the deposition period has been estimated between 5-15 Ma, since the limit between the Angostura and Ónzole formations remains unclear. For all the other samples, this constrain have been approximated at 9-15 Ma.

All the obtained thermal histories present consistent results, with predicted ages (expected or maximum likelihood) in agreement with observed ages within error bars (Fig. 6).

The thermal histories of all samples record a post-depositional heating phase, before a final cooling phase allowing the sample to crop out at the surface at the present time. Because all the samples were reset or partially reset during this burial event, the pre-depositional histories have been erased and thus the probability appears low and therefore, without real signification. No specific spatial trends related to geographic positions of the samples (N-S or E-W) is observed. The main differences between samples are the maximum heating temperature that ranges from ~50 to ~80°C and the starting time for the last cooling phase.

J o u r n a l P r e -p r o o f

Samples 12ECC05 and 12ECC07 display an exhumation path not very well constrained since their depositional ages is close to the exhumation timing. Samples 13ECC07 and 16MCC06

show similar young exhumation histories at ~2 Ma for a max burial at ~50°C quite well defined by a focused high relative probability of fit (red colored pixels in the model, Fig. 6). Samples 18BCB02, 13ECC08, 13ECC12A+B and 16MCC03 recorded similar exhumation timing around 5-6 Ma with burial reaching between ~60 and 80°C, relatively well constrained. Samples 13ECC04, 13ECC06, 13ECC11 and 13ECC34 indicate an exhumation at about 8-10 Ma with a burial around ~70-80 °C. The constraints on the model is acceptable except for 13ECC04 where the dataset is almost impossible to converge toward a model solution. The range of burial temperature obtained with the modeling is reasonable since the depth of the Angostura formation can locally reach 2000 m (Fig. 3) and maybe even deeper in the fault vicinities (Brandes et al., 2007;Serck and Braathen, 2018). Furthermore, the actual geothermal gradient in Ecuador is estimated at >35 °C/km [START_REF] Vieira | Assessment of Geothermal resources of South America -A new look[END_REF] and was probably high as well during Neogene, implying a maximum burial of 2000-2500 m according to our modeling results. The estimation of burial depths remains a rough approximation because little is known about the fault magnitude of movement and consequences on the sediment dynamics or the real geothermal gradient during Neogene.

DISCUSSION

Stratigraphic age and provenance

One of the keys of this study was to collect samples from the same stratigraphic level to be able to compare the results from a geographic perspective and exhumation pattern, in the aim to compare with the timing of the subduction of the Carnegie Ridge.

J o u r n a l P r e -p r o o f

Zircon U-Pb dating has been carried out to confirm that samples were collected from Angostura Formation. The YDZ ages show clearly that most of them are from this formation, with ages ranging from 9.6 ± 0.2 Ma to 11.5 ± 0.6 Ma (Table 3), in agreement with previously published biostratigraphic ages (Benítez, 1995;Deniaud, 2000;Ordóñez et al. 2006;Cantalamessa et al., 2007). The variation observed in the age-distribution diagram probably reflects the heterogeneities of the Angostura Formation in relation to structural discontinuities related to fault systems present in the studied area. In particular, the Jama Fault may control the spatial distribution of sediments [START_REF] Reyes | Évolution du relief le long des marges actives: Etude de la déformation Plio-Quaternaire de la cordillère côtière d'Equateur[END_REF], which could explain the different agedistribution patterns of samples 13ECC04 and 13ECC06. Similarly, for samples 13ECC07 and 16MCC03, the proximity of secondary faults (Fig. 2) could be responsible for their slightly different age-distribution profiles.

Three samples (12ECC05, 12ECC07, 18BCB02) display younger ages and could be attributed to the Ónzole Formation. However, the gradual transition between Angostura and Ónzole formations (Deniaud, 2000;[START_REF] Reyes | Évolution du relief le long des marges actives: Etude de la déformation Plio-Quaternaire de la cordillère côtière d'Equateur[END_REF] does not permit to be certain that those samples belong to one or the other formations. For this reason, the stratigraphic constraint introduced into QTQt was set up at 5-15 Ma, for the three samples mentioned above and at 9-10 Ma for all the other samples, to leave a maximum latitude to the software to reach a solution (Fig. 6). In the case of sample 18BCB12, in order to make the data set converge to find a solution, the modeling imposes a deposition age closer to ~10 Ma, whereas for 12ECC05 and 12ECC07 the deposition age would be closer to ~5-6 Ma (Fig. 6). Therefore, sample 18BCB02 is probably from the Angostura Formation, near or in the transition to the Ónzole Formation, while 12ECC05 and 12ECC07 are likely to belong to the Ónzole Formation and have not been reset.

Exhumation timing and implications

J o u r n a l P r e -p r o o f

The modeling results display three different timing of exhumation at ~2 Ma, ~5-6 Ma and ~8-10 Ma for a burial which could reach a maximum temperature of ~80°C, without a specific pattern related to the geographic position of the sample along the coast. The question is how to interpret this result in the context of the Ecuadorian Coastal Cordillera.

The first stage of exhumation is recorded at ~8-10 Ma for three samples (13ECC06; 13ECC11, 13ECC34), all located close to fault systems (Fig. 2; Jama, Tanigüe and Jipijapa/Cascol faults respectively). Most of the previous studies investigating rock exhumation have been focused along the Andes (Witt et al., 2017(Witt et al., , 2019)), where widespread cooling episodes has been reported for the last 25 Ma (Spikings and Crowhurst, 2004). One of these events have been estimated between 15 and 9 Ma, using fission track analysis [START_REF] Spikings | Along-strike variations in the thermal and tectonic response of the continental Ecuadorian Andes to the collision with heterogeneous oceanic crust[END_REF]Spikings and Crowhurst, 2004;[START_REF] Spikings | Syn-and post-accretionary cooling history of the Ecuadorian Andes constrained by their in-situ and detrital thermochronometric record[END_REF][START_REF] Spikings | Rock uplift and exhumation of continental margins by the collision, accretion, and subduction of buoyant and topographically prominent oceanic crust[END_REF] and attributed to the collision of the Carnegie Ridge against the Ecuadorian margin [START_REF] Spikings | Along-strike variations in the thermal and tectonic response of the continental Ecuadorian Andes to the collision with heterogeneous oceanic crust[END_REF]2010). This could be an explanation, although all the samples indicating an exhumation time at ~8-10 Ma are located in a fault vicinity while those recording younger events are spread out all along the Coastal Cordillera. Therefore, this ~8-10 Ma exhumation period could be the result of a tectonically controlled burial and exhumation pattern locally enhanced by faults systems.

The second and third exhumation periods are defined at ~5-6 Ma and ~2 Ma, respectively. Spikings and Crowhurst (2004) have identified, using apatite (U-Th-Sm)/He thermal history models, similar cooling events at ~5. Ma in the Cordillera Real of Ecuador (Fig. 1). Furthermore, an unconformity has been identified at about ~5 Ma underlying the base of the Borbón Formation (Deniaud, 2000;Di Celma et al., 2010) which has been considered as the Upper Ónzole Formation into the Borbón basin by [START_REF] Reyes | Évolution du relief le long des marges actives: Etude de la déformation Plio-Quaternaire de la cordillère côtière d'Equateur[END_REF]. This represents a regional episode of hiatus or erosion in the Coastal Cordillera (Deniaud, 2000). Low angular unconformities are described by [START_REF] Reyes | Évolution du relief le long des marges actives: Etude de la déformation Plio-Quaternaire de la cordillère côtière d'Equateur[END_REF] in the Borbón J o u r n a l P r e -p r o o f Formation and are interpreted as tectonic activity related to the Coastal Cordillera uplift.

Since that time, the paleo-bathymetry of the Borbón Formation has remained between intertidal and neritic environments, revealing a shallowing of the seafloor, significant sediment failure and mass-wasting, which occurred in response to the margin tilting (Di Celma et al., 2010) and probably to the beginning of the Coastal Cordillera uplift.

The geodynamic environment of the Borbón Formation is consistent with the exhumation timing revealed by our results, considering that this regional unconformity described along the onshore forearc basins is also revealed along the offshore forearc domain [START_REF] Hernández | The Neogene forearc basins of the Ecuadorian Shelf (1°N-2°20'S): preliminary interpretation of a dense grid of MCS data[END_REF]Hernández et al., 2020). Additionally, into the Esmeraldas submarine canyon area (Fig. 1 and2), [START_REF] Collot | The Esmeraldas Canyon: A Helpful Marker of the Pliocene-Pleistocene Tectonic Deformation of the North Ecuador-Southwest Colombia Convergent Margin[END_REF] evidences the development of the canyon by several incision pulses, one of which is dated around ~5-6 Ma and correlated to an important uplifting episode of at least 1 km, along the offshore forearc domain. Another is estimated to take place during Pleistocene and is attributed to regional tectonic events.

Geodynamic control of the Coastal Cordillera exhumation

Convergence rate and obliquity of the Nazca plate motion relative to South America plate during the last 25 Ma [START_REF] Somoza | Late Cretaceous to recent plate motions in western South America revisited[END_REF] is characterized by ENE directed convergence for a rate decreasing continuously from values at ~15 cm/yr during the Cenozoic to present-day values around ~6-7 cm/yr. This sub-continuous decrease of the convergence rates is not obviously correlated to discontinuous exhumation events inferring from our data in the forearc domain. Cerpa and Arcay (2020) propose that, above a stagnating Nazca plate, the slow-down of the absolute westward motion of the South-American continent in the last 25 Ma [START_REF] Somoza | Late Cretaceous to recent plate motions in western South America revisited[END_REF] might contribute to the upward displacement of the forearc area while the arc region subsides. This corresponds to the actual morphology of the forearc and arc regions in Ecuador with the formation of the Coastal Cordillera while the arc J o u r n a l P r e -p r o o f is located in the Interandine Depression. Therefore, it is possible to consider a global kinematic cause for the forearc rise. It could be initiated ~25 Ma ago when the convergence rate starts to decrease and recorded as an exhumation period at ~8-10 Ma in the forearc region, since the time response to adjust kinematic changes of subduction could take between 10 to 35 Ma depending of the convergence rate variation (Cerpa et al., 2018). However, if a global uplift of most of the coast along the South America margin is observed, the uplift rate is enhanced where aseismic ridge is subducted [START_REF] J O U R N A L P R E -P R O O F Martinod | How do subduction processes contribute to forearc Andean uplift? Insights from numerical models[END_REF]. In Ecuador, the subduction of the Carnegie Ridge is then a possible booster for the upward displacement of the forearc domain.

Debate persists regarding the geodynamic influence of subducting aseismic ridges on the relief building along forearc domain. [START_REF] Henry | Upper Pleistocene uplifted shorelines as tracers of (local rather than global) subduction dynamics[END_REF], propose that the large-scale geodynamic setting of subduction zones is of secondary importance to the uplift of the coastal margin. Instead, the first order parameter is represented by the small-scale heterogeneities of the subducting plate, as for instance, the subduction of aseismic ridges. Clift and Ruiz (2007) suggest that temporary uplift due to arc-ridge collisions does not extend far landward from the trench. In contrast, Espurt et al. (2007;2010) and Gautheron et al. (2013b) illustrate its influence until the Amazonian foreland basin. [START_REF] Morell | Seamount, ridge, and transform subduction in southern Central America[END_REF] shows the influence of the Cocos ridge subduction (Costa Rica), from the trench inner wall to the volcanic arc.

In Ecuador, the subduction age for the Carnegie Ridge is controversial [START_REF] Michaud | Backbone of the Americas: Shallow Subduction, Plateau Uplift and Ridge and terrane Collision[END_REF] and the morphology of the ridge subducted part is unknown and could have been much different of what is currently observed. On the Nazca plate, the Carnegie Ridge exhibits in its midst a topographic low (saddle) at 2400-m depth [START_REF] Michaud | A honeycomb seafloor morphology in carbonate sediment of the Carnegie Ridge (offshore Ecuador): Formation and potential geodynamic significance[END_REF], meanwhile the segment which is close to the trench is at 700 m depth. Indeed, substantial along-strike relief differences along the volcanic aseismic ridges are currently observed and when they enter into subduction, they could produce different magnitudes of deformation in the forearc.

J o u r n a l P r e -p r o o f

Consequently, we cannot rule out a scenario of an early arrival of the Carnegie Ridge, with a smoother ancient ridge segment subducting at ~10-12 Ma, without causing dramatic deformation in the forearc region, only activating some pre-existing structures (faults), implying an exhumation at ~8-10 Ma. In this hypothesis, this segment, still buoyant enough, would have influenced the slab dip angle as inferred from the arc eastward migration and broadening at ~10-12 Ma [START_REF] Schütte | Geodynamic controls on Tertiary arc magmatism in Ecuador: Constraints from U-Pb zircon geochronology of Oligocene-Miocene intrusions and regional age distribution trends[END_REF].

On the other hand, a reappraisal of Collot et al. (2009) model's about the initiation of the Carnegie Ridge subduction using the plate convergence kinematic model of [START_REF] Nocquet | Motion of continental slivers and creeping subduction in the northern Andes[END_REF], suggests that the Carnegie Ridge entered in subduction ~5-6 Ma ago [START_REF] Collot | The Esmeraldas Canyon: A Helpful Marker of the Pliocene-Pleistocene Tectonic Deformation of the North Ecuador-Southwest Colombia Convergent Margin[END_REF]. In this model, the northern flank of the Carnegie Ridge remains oblique in relation to the trench direction. Assuming that the obliquity of the flank extends down to the slab, it would imply that since ~5-6 Ma the Carnegie Ridge flank migrated southward along the trench. The model of Collot et al. (2009) is compatible with both the location of the Carnegie Ridge under the entire present-day Coastal Cordillera, and the exhumation timing obtained in this work at ~5-6 Ma. After the initiation at ~5-6 Ma, subduction of sea-floor relief roughness or thickened oceanic crust might have been responsible for heterogeneous uplift of the Coastal Cordillera, as shown by our modeling with a Pleistocene exhumation event.

Consequently, the intermediate exhumation period, at ~5-6 Ma, could be related to the Carnegie Ridge arrival into the trench or alternatively to the subduction of an along-strike positive relief of the ridge. In the hypothesis of a ~5-6 Ma Carnegie Ridge arrival, subduction erosion could explain the significant eastward migration of the volcanic arc region as proposed by [START_REF] Schütte | Geodynamic controls on Tertiary arc magmatism in Ecuador: Constraints from U-Pb zircon geochronology of Oligocene-Miocene intrusions and regional age distribution trends[END_REF]. Furthermore, kinematic changes could also support the dynamics of the volcanics arc [START_REF] Schütte | Geodynamic controls on Tertiary arc magmatism in Ecuador: Constraints from U-Pb zircon geochronology of Oligocene-Miocene intrusions and regional age distribution trends[END_REF].

Finally, the difficulty of identifying a geographic pattern for the different periods of exhumation along the Coastal Cordillera is probably related to the fact that this area is J o u r n a l P r e -p r o o f segmented by faults systems, deformed by folds, and still unstable. As a result, little is known about the sediment thickness and its variations along the coast, or thermal status of the crust during the Neogene, limiting the interpretation of our thermochronological data set.

Moreover, the unknown geometry of the subducted part of Carnegie Ridge as the uncertainties about the age of the beginning of its subduction, are as many limitations to studies reconstructing ridge-trench interactions by considering major deformation episodes in the forearc domain.

CONCLUSIONS

New geochronology data (zircon U-Pb dating) allow us to define a range of maximum deposition ages for the Angostura Formation from 9.6 ± 0.2 Ma to 11.5 ± 0.6 Ma and to suggest that fault systems in the area may disturb the spatial distribution of sediments. The QTQt modeling of our AHe dataset display three different timings of exhumation along the Costal Cordillera, independent of the sample geographic locations.

The oldest event, at ~8-10 Ma, evidenced locally along fault systems, can be interpreted either in relation to regional overriding plate kinematic changes (slowdown of absolute motion in the last ~25 Ma) or in response to smooth segment early arrival of the Carnegie Ridge into the subduction.

An exhumation event at ~5-6 Ma has been identified and can be interpreted either as the initiation timing of the Carnegie Ridge subduction or the subduction of an along-strike positive relief of the ridge. Similarly, subduction of sea-floor relief roughness or thickened oceanic crust could be responsible for heterogeneous uplift of the Coastal Cordillera during the Pleistocene (~2 Ma) inducing exhumation as recognized in our modeling. The absence of geographic pattern of exhumation along the studied area could be explained by variation of J o u r n a l P r e -p r o o f sediment thickness and thermal status of the crust along the coast, especially since the area is highly segmented by fault systems, deformed by folds and still highly unstable. However, estimating the magnitude of the exhumation remains speculative since little is known about the fault kinematics or the geothermal gradient during the Neogene.

Finally, our interpretations are corroborated by previous published studies and demonstrate that the sensitivity of the apatite (U-Th-Sm)/He thermochronometer can provide further constraints on the exhumation pattern in sedimentary domains. In the left corner: Geodynamic framework where the Nazca plate motion related to South American continent is from [START_REF] Trenkamp | Wide plate margin deformation, southern Central America and northwestern South America, CASA GPS observations[END_REF], the dotted black lines represent North Andean Silver boundary, and the black rectangle indicates the studied area. (Benítez, 1995;Deniaud, 2000;Ordóñez et al. 2006;Cantalamessa et al., 2007). (black line) represents the mean of each thermal histories that is used to calculate the predicted age (black triangles). In addition, the colour scale presents the relative probability of each thermal history, from deep blue (low probability) to red (high probability). The maximum likelihood probability (orange line) of thermal history contains green to red colours and the maximum likelihood predicted ages are also reported in the predicted-observed inserted diagram (orange bars). For each model, the exhumation timing and the maximum burial temperature are indicated under a similar colour code for each distinct period of exhumation.

FIGURE CAPTIONS

Table 1.: Sample information Table 2.: Apatite (U-Th-Sm)/He data Table 3.: Estimations of the youngest detrital zircon ages APPENDIX J o u r n a l P r e -p r o o f estimated by biostratigraphy (Benítez, 1995;Deniaud, 2000;Ordóñez et al. 2006;Cantalamessa et al., 2007). Each samples is identified by a different colour code identical in figures 5 and A.3. (Benítez, 1995;Deniaud, 2000;Ordóñez et al. 2006;Cantalamessa et al., 2007). Each samples is identified by a different colour code identical in figures 5 and A.2. 190-191, 383-402. Collot, J.Y., Michaud, F., Alvarado, A., Marcaillou, B., Sosson, M., Ratzov, G., Migeon, S., Calahorrano, A., Pazmino, A., 2009. Visión general de la morfología submarina del margen convergente de Ecuador-Sur de Colombia : implicaciones sobre la transferencia de masa y la edad de J o u r n a l P r e -p r o o f Deniaud, Y., Baby, P., Basile, C., Ordoñez, M., Montenegro, G., Mascle, G., 1999. Opening and tectonic and sedimentary evolution of the Gulf of Guayaquil: Neogene and Quaternary fore-arc basin of the south Ecuadorian Andes. C. R. A. Sci. Series IIA Earth Planet. Sci. 328, 181-187, doi:10.1016 /s1251-8050(99)80094-9 Espurt, N., Baby, P., Brusset, S., Roddaz, M., Hermoza, W., Regard, V., Bolanos, R., 2007. How does the Nazca Ridge subduction influence the modern Amazonian foreland basin? Geology 35, 515-518.

Espurt N., Baby P., Brusset S., Roddaz M., Hermoza W., Barbarand J., 2010. The Nazca Ridge and uplift of the Fitzcarrald Arch: implications for regional geology in northern South America. In: Hoorn J o u r n a l P r e -p r o o f (2σ). eU is the effective uranium = U + 0.243Th + 0.0046Sm.

J o u r n a l P r e -p r o o f

Please fill in the table below according to following:

-list the authors in order in which they are stated in manuscript. This way each author is assigned with number for further identification.

-each author should sign this document (on designated place in the table ). By signing this form authors take full responsibility for all statements it contains.

No.

Author's full name (in capital letters) Author's signature

1.

Stephanie Brichau

2.

Pedro Reyes

3.

Cecile Gautheron

4.

Maria José Hernandez

5.

François Michaud

6.

Mathieu Leisen

7.

Arnaud Vacherat 8.

Marianne Saillard

9.

Jean-Noel Proust

  .1, and A.2 and Concordia plot diagram under the Figure A.1.

Figure 1 :

 1 Figure 1: Elevation map of the Carnegie Ridge-Ecuador margin collision area (from Michaud

Figure 2 :

 2 Figure 2: Simplified geologic map (location on Fig.1) from Reyes et Michaud (2012) of the

Figure 3 :Figure 4 :

 34 Figure 3: Simplified litho-stratigraphic log of the Ecuadorian Coastal Cordillera (from Reyes,

Figure 5 :

 5 Figure 5: A) Apatite He ages versus effective Uranium (eU) content diagram showing a

Figure 6 :

 6 Figure 6: QTQt thermal histories and observed vs predicted AHe ages, for each dated sample

Figure A. 1 :

 1 Figure A.1: U-Pb data in Wetherill Concordia diagrams with insert showing the youngest

Figure A. 2 :

 2 Figure A.2: Apatite He ages versus effective Uranium (eU) content diagrams for every

Figure A. 3 :

 3 Figure A.3: Apatite He ages versus Th/U ratio diagrams for every individual sample showing

Table A. 1 :

 1 Zircon U-Pb dating operating conditions for LA-ICP-MS analyses Table A.2: Zircon U-Pb data REFERENCES J o u r n a l P r e -p r o o f Cantalamessa, G., Di Celma, C., Ragaini, L., Valleri, G., Landini, W., 2007. Sedimentology and highresolution sequence stratigraphy of the late middle to late Miocene Angostura Formation (western Borbón Basin, northwestern Ecuador). J. Geol. Soc. 164, 653-665. Cerpa, N. G., Guillaume, B., & Martinod, J. 2018. The interplay between overriding plate kinematics, slab dip and tectonics. Geophysical Journal International, 215(3), 1789-1802. Cerpa, N. G., Arcay, D., 2020. Overriding Plate Velocity Control on Surface Topography in 2-D Models of Subduction Zones. Geochem. Geophys. Geosyst. 21, e2019GC008900. Chiaradia, M., Müntener, O., Beate, B., 2020. Effects of aseismic ridge subduction on the geochemistry of frontal arc magmas. Earth Planet Sci. Lett. 531, 115984. Clift, P.D., Ruiz, G.M., 2007. How does the Nazca Ridge subduction influence the modern Amazonian foreland basin? Comment and Reply: Comment. Geology, 35, e162-e162. Cloos, M., Shreve, R.L., 1988. Subduction-channel model of prism accretion, melange formation, sediment subduction, and subduction erosion at convergent plate margins: 2. Implications and discussion. PAGEOPH 128, 501-545. https://doi.org/10.1007/BF00874549. Cochrane, R., Spikings, R., Gerdes, A., Ulianov, A., Mora, A., Villagómez, D., Putlitz, B., Chiaradia, M., 2014. Permo-Triassic anatexis, continental rifting and the disassembly of western Pangaea. Lithos

J

  o u r n a l P r e -p r o o f J o u r n a l P r e -p r o o f J o u r n a l P r e -p r o o f r n a l P r e -p r o o f J o u r n a l P r e -p r o o f J o u r n a l P r e -p r o o f J o u r n a l P r e -p r o o f r n a l P r e -p r o o f • Three main periods of exhumation have been recognized in thre Coasteal Cordillera of Ecuador • Overriding plate kinematic changes can play a significant role in exhumation processes • The Apatite (U-Th-Sm)/He thermochronometer is sensitive enough to provide reliable constraints in sedimentary domains J o u r n a l P r e -p r o o f 1 AUTHORS STATEMENT FOR PUBLICATION Manuscript title: First timing constraints on the Ecuadorian Coastal Cordillera exhumation: geodynamic implications Corresponding author's full name: Stephanie Brichau Please note that all contributing authors are obligated to sing Authors statement for publication form otherwise the manuscript will not be published.

10.

  Paul O'Sullivan J o u r n a l P r e -p r o o f

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  Deniaud, Y., 2000. Enregistrements sédimentaire et structural de l'évolution géodynamique des Andes Equatoriennes au cours du Néogène: Etude des bassins d'avant-arc et bilans de masse. PhD thesis.

	Université	Joseph	Fourier,	Grenoble,	http://horizon.documentation.ird.fr/exl-
	doc/pleins_textes/divers14-01/010027994

Di Celma, C., Cantalamessa, G., Landini, W., Ragaini, L., 2010. Stratigraphic evolution from shoreface to shelf-indenting channel depositional systems during transgression: Insights from the lower Pliocene Súa Member of the basal Upper Onzole Formation, Borbón Basin, northwest Ecuador. Sediment. Geol., 223, 162-179. Dickinson, W. R., Gehrels, G. E., 2009. U-Pb ages of detrital zircons in Jurassic eolian and associated sandstones of the Colorado Plateau: Evidence for transcontinental dispersal and intraregional recycling of sediment. Geol. Soc. Am. Bull. 121, 408-433, doi:10.1130/b26406.1 Evans, C.D.R., Whittaker, J.E., 1982. The geology of the western part of the Borbón basin, northwest

Ecuador. In: Leggett, J.K., (Eds.), Trench-Forearc Geology. Geological Society of London Special

Publication 10,[191][192][193][194][195][196][197][198][199][200]

Table 1 .

 1 Witt, C., Bourgois, J., 2010. Forearc basin formation in the tectonic wake of a collision-driven, coastwise migrating crustal block: The example of the North Andean block and the extensional Gulf of Guayaquil-Tumbes Basin (Ecuador-Peru border area). Geol. Soc. Am. Bulletin 122, 89-108.Tracking ancient magmatism and Cenozoic topographic growth within the Northern Andes forearc:Constraints from detrital U-Pb zircon ages. Geol. Soc. Am. Bulletin 129, 415-428. Sample information

				Ratios				Ages
	Analysis Number	[U]	[Th]	Th/U 207Pb/	(±2s) 206Pb/	(±2s) 207Pb/	(±2s) 207Pb/	(+2s) (-2s) 206Pb/	(+2s)	(-2s) 207Pb/2	(+2s)	(-2s)	%	Best	(±2σ)
		ppm	ppm	235U	238U	206Pb		235U			238U			06Pb		discor.	Ages
																(Ma)
	12ECC05 (n=29)
	2121AZ1_1	106	44	0.4 0.0146 0.0256 0.0008 0.0003 0.1368 0.2457	14.0 24.7 24.4	5.0	1.8	1.8 2187.2 4374.4 2114.7	5.2	2.3
	2121AZ1_2	58	23	0.4 0.0152 0.0280 0.0008 0.0004 0.1376 0.2603	14.1 26.0 25.7	5.2	2.3	2.3 2197.7 4395.5 2190.7	5.5	2.2
	2121AZ1_5	65	23	0.4 0.0282 0.0437 0.0009 0.0003 0.2374 0.3803	28.6 44.3 43.3	5.5	2.2	2.2 3102.6 6080.1 1812.5	6.2	1.9
	2121AZ1_9	83	35	0.4 0.0165 0.0265 0.0010 0.0003 0.1240 0.2029	16.7 26.9 26.5	6.2	1.9	1.9 2013.9 4027.8 2011.6	6.2	0.8
	2121AZ1_13	302	202	0.7 0.0092 0.0080 0.0010 0.0001 0.0687 0.0607	9.1	7.9	7.9	6.2	0.8	0.8	889.8 1779.6 1433.6	6.7	1.5
	2121AZ1_32	132	38	0.3 0.0124 0.0189 0.0010 0.0002 0.0868 0.1340	12.2 18.7 18.5	6.7	1.5	1.5 1356.9 2713.8 2064.7	6.7	1.5
	2121AZ1_3	130	43	0.3 0.0143 0.0171 0.0010 0.0002 0.1003 0.1217	13.9 16.6 16.5	6.7	1.5	1.5 1629.1 3258.2 1676.2	6.7	0.9
	2121AZ1_26	264	104	0.4 0.0094 0.0081 0.0010 0.0001 0.0659 0.0573	9.5	8.2	8.2	6.7	0.9	0.9	802.2 1604.5 1433.5	6.8	1.9
	2121AZ1_23	91	36	0.4 0.0185 0.0277 0.0011 0.0003 0.1274 0.1937	17.8 26.5 26.2	6.8	1.9	1.9 2062.0 4123.9 1898.6	7.0	2.6
	2121AZ1_27	104	40	0.4 0.0148 0.0239 0.0011 0.0004 0.0988 0.1640	14.8 24.0 23.7	7.0	2.6	2.6 1601.4 3202.7 2117.4	7.1	1.4
	2121AZ1_10	138	71	0.5 0.0163 0.0202 0.0011 0.0002 0.1069 0.1338	16.6 20.5 20.3	7.1	1.4	1.4 1747.8 3495.6 1694.0	7.2	1.9
	2121AZ1_16	113	60	0.5 0.0179 0.0199 0.0011 0.0003 0.1157 0.1327	17.9 19.9 19.8	7.2	1.9	1.9 1891.1 3450.9 1561.3	7.5	0.6
	2121AZ1_21	503	306	0.6 0.0083 0.0060 0.0012 0.0001 0.0513 0.0375	8.2	5.9	5.9	7.5	0.6	0.6	256.5 513.0 1350.8	7.6	1.1
	2121AZ1_11	253	218	0.9 0.0126 0.0131 0.0012 0.0002 0.0774 0.0811	11.8 12.2 12.1	7.6	1.1	1.1 1130.9 2261.9 1587.9	7.7	2.9
	2121AZ1_4	45	19	0.4 0.0298 0.0444 0.0012 0.0004 0.1815 0.2787	27.5 40.9 40.1	7.7	2.9	2.9 2666.2 5332.3 1815.1	7.8	2.2
	2121AZ1_30	69	37	0.5 0.0265 0.0412 0.0012 0.0003 0.1591 0.2517	24.3 37.8 37.1	7.8	2.2	2.2 2446.4 4892.7 1887.9	8.1	2.4
	2121AZ1_14	87	33	0.4 0.0195 0.0294 0.0013 0.0004 0.1126 0.1730	19.3 29.1 28.7	8.1	2.4	2.4 1841.5 3683.1 1954.4	8.3	1.5
	2121AZ1_18	207	118	0.6 0.0110 0.0130 0.0013 0.0002 0.0617 0.0736	10.6 12.6 12.5	8.3	1.5	1.5	662.4 1324.7 1865.3	8.4	1.2
	2121AZ1_17	215	165	0.8 0.0137 0.0125 0.0013 0.0002 0.0759 0.0703	14.1 12.9 12.8	8.4	1.2	1.2 1093.3 2186.6 1448.1	8.6	1.2
	2121AZ1_15	178	54	0.3 0.0147 0.0125 0.0013 0.0002 0.0795 0.0685	14.8 12.5 12.4	8.6	1.2	1.2 1185.7 2371.4 1349.6	9.0	2.2
	2121AZ1_24	85	34	0.4 0.0230 0.0342 0.0014 0.0003 0.1191 0.1788	22.0 32.6 32.1	9.0	2.2	2.2 1943.1 3886.3 1902.3	9.4	1.8
	2121AZ1_12	136	76	0.6 0.0156 0.0208 0.0015 0.0003 0.0782 0.1052	15.1 20.1 19.9	9.4	1.8	1.8 1151.0 2301.9 1913.9	9.5	1.1
	2121AZ1_25	241	76	0.3 0.0135 0.0107 0.0015 0.0002 0.0661 0.0528	13.2 10.4 10.4	9.5	1.1	1.1	810.8 1621.5 1335.0	10.5	1.9
	2121AZ1_31	105	55	0.5 0.0199 0.0237 0.0016 0.0003 0.0887 0.1070	19.4 23.1 22.9	10.5	1.9	1.9 1396.7 2793.5 1713.8	10.7	1.7
	2121AZ1_6	98	71	0.7 0.0283 0.0306 0.0017 0.0003 0.1238 0.1356	28.1 30.4 29.9	10.7	1.7	1.7 2012.3 3116.0 1487.9	10.7	2.2
	2121AZ1_22	78	31	0.4 0.0243 0.0294 0.0017 0.0003 0.1060 0.1303	23.1 27.9 27.5	10.7	2.2	2.2 1732.5 3465.0 1673.8	12.0	1.8
	2121AZ1_29	106	58	0.5 0.0292 0.0227 0.0028 0.0004 0.0758 0.0597	26.8 20.7 20.5	18.0	2.3	2.3 1090.0 2180.1 1271.5	18.0	2.3
	2121AZ1_8	89	25	0.3 0.0342 0.0282 0.0039 0.0005 0.0637 0.0532	36.2 29.7 29.3	25.0	3.5	3.5	732.7 1465.5 1399.7	25.0	3.5
	2121AZ1_19	298	214	0.7 0.8725 0.0384 0.1038 0.0029 0.0610 0.0027 634.1 26.9 26.5 636.6	17.2	17.2	638.0	95.9	93.1	636.6	17.2
	12ECC07 (n=122)
	7ECC12_27	86	47	0.6 0.0129 0.0071 0.0009 0.0002 0.0100 0.0730	13.1	7.3	7.3	5.5	1.3	1.3 -4900.0 2300.0 2300.0	5.5	1.3
	7ECC12_9	129	31	0.2 0.0101 0.0037 0.0010 0.0001 0.0890 0.0520	10.1	3.7	3.7	6.2	0.7	0.7 -350.0 830.0 830.0	6.2	0.7
	7ECC12_14	340	421	1.2 0.0075 0.0050 0.0010 0.0001 0.0460 0.0520	7.4	5.0	5.0	6.3	0.8	0.8 -2500.0 1600.0 1600.0	6.3	0.8
	7ECC12_12	2665 2492	0.9 0.0068 0.0007 0.0010 0.0000 0.0470 0.0045	6.9	0.7	0.7	6.7	0.3	0.3	40.0 170.0 170.0	6.7	0.3
	7ECC12_29	185	177	1.0 0.0128 0.0049 0.0011 0.0002 0.0930 0.0500	12.6	4.9	4.9	6.8	1.0	1.0 -1300.0 1300.0 1300.0	6.8	1.0

doi:10.1130/b26386.1

Witt, C., Rivadeneira, M., Poujol, M., Barba, D., Beida, D., Beseme, G., Montenegro, G., 2017. Witt, C., Reynaud, J.Y., Barba D., Poujol M., Aizprua C., Rivadeneira M., Amberg C.,

2019. From accretion to forearc basin initiation: The case of SW Ecuador, Northern Andes. Sedim. Geol. https://doi.org/10.1016/j.sedgeo.2018.11.009 Zeitler, P., Brown, R., Hackspacher, P., 2017. Better tools for tracing the thermal history of rocks. Eos, 98, https://doi.org/10.1029/2017EO073479 Zeumann, S., Hampel, A., 2016. Three-dimensional finite-element models on the deformation of forearcs caused by aseismic ridge subduction: The role of ridge shape, friction coefficient of the plate interface and mechanical properties of the forearc. Tectonophysics 684, 76-91. J o u r n a l P r e -p r o o f APPENDIX Table A.2. Zircon U-Pb data J o u r n a l P r e -p r o o f

Table 2 .

 2 Apatite (U-Th-Sm)/He data

	Sample	Aliquot Rs weight F T	4He	U	Th	Sm	eU Th/U Age Age c ± σ
			(µm)	(µg)		(ncc/g) (ppm) (ppm) (ppm) (ppm)		(Ma) (Ma) (Ma)
	12ECC05	G	56	3.7	0.78 5170	6.0	22.3	13.5	11.5 3.7	3.8	4.8	0.4
		H	94	20.7	0.88 9740	10.3 27.1	18.6	16.9 2.6	4.8	5.5	0.4
		I	61	5.9	0.81 12309 18.0 39.9	23.3	27.8 2.2	3.7	4.6	0.4
		J	45	2.0	0.69 6152	5.7	24.0	16.1	11.6 4.2	4.4	6.4	0.5
		L	76	8.8	0.84 16049	6.5	20.2	21.3	11.5 3.1 11.6 13.9	1.1
		M	80	12.5	0.84 7973	9.4	29.2	21.8	16.6 3.1	4.0	4.8	0.4
		N	58	4.2	0.79 6850	5.2	12.0	9.1	8.1	2.3	7.0	8.9	0.7
		O	68	7.2	0.81 14788 11.3 35.3	18.2	20.0 3.1	6.2	7.6	0.6
		P	92	19.0	0.88 3010	4.3	11.9	15.1	7.3	2.7	3.4	3.9	0.3
	12ECC07	A	65	7.1	0.82 8209	8.8	31.0	70.4	16.7 3.5	4.2	5.1	0.4
	13ECC04 13ECC06 13ECC07	B C D C D E F G H I J A B C E H I J A B	88 77 41 48 46 48 54 46 51 42 36 61 59 68 64 45 45 43 51 40 J o u r n a l P r e -p r o o f 16.1 0.87 1692 2.9 10.5 26.2 5.5 3.7 11.0 0.85 5139 5.5 18.6 41.2 10.2 3.4 1.8 0.66 14477 6.9 20.8 0.0 12.0 3.0 10.1 15.3 2.6 3.0 4.3 5.0 2.8 0.77 1864 1.7 9.5 86.5 4.4 5.6 3.8 5.0 2.1 0.69 3177 2.8 18.8 126.5 7.9 6.8 3.6 5.2 3.2 0.75 2362 4.1 12.9 79.9 7.6 3.2 2.7 3.6 3.8 0.79 2304 2.4 10.1 89.2 5.2 4.3 3.9 5.0 1.9 0.74 9615 12.0 27.1 142.4 19.2 2.3 4.3 5.8 2.8 0.75 13675 3.3 12.0 160.9 7.0 3.6 17.8 23.7 2.1 0.72 37021 11.9 191.8 204.1 59.5 16.1 5.3 7.4 1.0 0.61 784 1.1 28.4 0.0 8.0 25.1 0.8 1.4 4.6 0.80 4089 2.3 11.3 63.9 5.3 5.0 6.7 8.5 3.5 0.76 4192 2.8 15.2 76.4 6.9 5.3 5.3 7.0 8.4 0.83 2346 1.9 8.4 30.9 4.1 4.4 4.9 5.9 6.4 0.80 4049 2.0 7.4 133.3 4.4 3.7 8.6 10.8 1.5 0.69 8794 5.1 21.5 258.4 11.6 4.2 6.9 10.1 2.5 0.74 5927 5.1 20.2 160.2 10.7 4.0 4.9 6.6 1.8 0.76 2868 1.1 10.3 0.0 3.6 9.4 6.6 8.7 3.6 0.77 5737 4.0 18.5 83.4 8.9 4.6 5.6 7.3 1.9 0.67 11407 9.5 23.9 89.4 15.7 2.5 6.2 9.2	0.2 0.4 1.2 0.4 0.4 0.3 0.4 0.5 1.9 0.6 0.1 0.7 0.6 0.5 0.9 0.8 0.5 0.7 0.6 0.7
		C	44	1.8	0.72 2305	2.0	14.9	79.9	6.0	7.6	3.4	4.8	0.4
		D	46	2.4	0.72 56381 17.2 53.4 124.5 30.8 3.1 15.6 21.6	1.7
		E	46	2.6	0.75 18241 14.3 38.1	59.1	23.9 2.7	6.4	8.6	0.7
		F	41	1.4	0.71 17303 10.5 34.8 233.2 20.0 3.3	7.5	10.6	0.8
		G	34	1.0	0.68 15537 12.3 34.4 207.8 21.7 2.8	6.2	9.2	0.7
		H	38	1.4	0.71 15709 15.7 48.1 185.4 28.2 3.1	4.8	6.7	0.5
		I	33	0.9	0.66 85865 11.0 51.0 163.7 24.2 4.6 30.5 46.1	3.7
		J	48	2.3	0.75 15196	9.3	30.1 165.2 17.4 3.2	7.6	10.1	0.8
	13ECC08	A	40	1.4	0.64 48265 53.5 71.8 175.5 71.8 1.3	5.6	8.8	0.7
		C	46	2.6	0.75 12732 12.4 83.7 125.9 33.3 6.7	3.3	4.4	0.3
		D	39	1.2	0.64 5170	6.9	22.2 205.0 13.3 3.2	3.4	5.4	0.4
	13ECC11	A	71	8.7	0.82 2672	2.3	6.5	46.1	4.1	2.8	5.6	6.9	0.6
		C	68	11.1	0.81 1349	1.1	2.3	48.7	1.8	2.1	6.7	8.3	0.7
		D	50	2.8	0.75 13539	1.9	11.5	51.2	4.9	6.0 23.9 31.9	2.5
		E	57	4.5	0.77 3104	3.0	11.5 196.5	6.7	3.8	4.3	5.6	0.4
		F	60	5.2	0.81 4567	3.1	9.0	71.1	5.6	2.9	7.1	8.8	0.7
		G	58	4.7	0.78 15249	6.0	14.7	89.8	10.0 2.4 13.1 16.9	1.4
		J	76	10.8	0.81 2483	2.1	3.5	9.7	3.0	1.6	6.9	8.5	0.7

(U-Th)/He ages were performed by laser heating for He extraction and ICP-MS for U-Th determinations at GEOPS Université Paris Sud, France. The estimated analytical uncertainty for He ages is about 8%

Table 3 .

 3 Estimations of the youngest detrital zircon ages.

	Sample Name Number of grain Age ± 2σ MSWD Youngest concordant
		in cluster	(Ma) (Ma)		single age*
	12ECC05	17	7.0	0.3	1.2	7.6 ± 1.1 Ma
	12ECC07	20	7.1	0.2	1.9	6.7 ± 0.3 Ma
	13ECC04	2	10.3	0.4	0.0	10.1 ± 0.5 Ma
	13ECC06	13	11.5	0.6	1.4	10.8 ± 0.8 Ma
	13ECC07	22	10.7	0.2	1.1	10.3 ± 0.6 Ma
	13ECC08	48	9.8	0.3	2.0	9.5 ± 1.1 Ma
	13ECC11	22	9.9	0.4	1.3	9.4 ± 0.9 Ma
	13ECC12A	23	9.6	0.3	1.4	8.6 ± 0.8 Ma
	13ECC12B	38	9.6	0.2	1.2	9.5 ± 1.0 Ma
	13ECC34	23	9.6	0.3	1.5	8.6 ± 0.7 Ma
	16MCC03	22	10.0	0.4	1.8	9.4 ± 0.8 Ma
	16MCC06	35	10.7	0.2	1.0	10.3 ± 0.6 Ma
	18BCB02	11	7.7	0.3	4.5	21.0 ± 0.8 Ma
	Systematic error estimated at 2.5%
	*at <15% maximum of discordancy

ACKNOWLEDGMENTS

This work was funded by the Institut de Recherche pour le Développement (IRD) and the Institut National des Sciences de l'Univers (INSU; CNRS-INSU-SYSTER-2016). It was carried out in the frame of the Proyecto Interno PII-DG-001-2015 (VIPSEPN) and Joint French-Ecuador Laboratory "Earthquakes and Volcanoes in the Northern Andes". We acknowledge support from IRD/ANR MARACAS program (ANR-18-CE31-0022). We also acknowledge support from IRD/ANR REMAKE program (ANR-15-CE04-0004) and UCA/JEDI project (ANR-15-IDEX-01). M-J Hernández acknowledges support provided by the Secretaría de Educación Superior, Ciencia, Tecnología e Innovacion (SENESCYT), and the Escuela Politécnica Nacional de Quito (EPN) through a PhD grant. We would like to thank, for their technical support during sample preparations, Magali Bonnefoy and Mathieu at Géosciences Azur and Sandrine Choy at Géosciences Environnement Toulouse, and during the (U-Th-Sm)/He analysis, Rosella Pinna-Jamme at Geosciences Paris Saclay University. Kerry Gallagher is thanked for the advices during QTQt modeling step. The editor Federico Davila and the two reviewers Guido M. Gianni and Nick Perez are warmly thanked for their constructive reviews. J o u r n a l P r e -p r o o f

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