Dario Imbraguglio
email: d.imbraguglio@inrim.it

Petrus Paulus

Maria Steur

Fernando Sparasci

P M Steur

to 273 K between LNE-CNAM and INRIM

Keywords: Fixed points, ITS-90, CSPRT, Comparison, Cryogenics

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

Introduction

Both INRIM and LNE-CNAM were among the laboratories participating in the Key Comparison 2 [1], promulgated in the 90's by the Consultative Committee for Thermometry (CCT-K2) to address the realizations of the International Temperature Scale of 1990 (ITS-90) from 13.8033 K to 273.16 K [2]. Since then, only a limited number of Key Comparisons have been conducted among national measurement institutes (NMIs), only bilateral or trilateral ones [3][4][5][6], and a full-fledged international effort for a repeat of CCT-K2 seems highly unlikely in the near future. Some have sustained that one can recognize the not too recent (1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005) international comparison of fixed point cells performed at PTB [7] as such but, since the measurements were done exclusively at the pilot's laboratory, no information can be extracted about the capabilities of the other participating laboratories, exactly the reason why Key Comparisons are performed.

Therefore, the present bilateral comparison between LNE-CNAM and INRIM, under the vestiges of the recently created Joint Research Laboratory for Fluid Metrology "Evangelista Torricelli", is considered a most welcome addition to the still scarce verification of the ongoing maintenance of activities concerning the realization of the ITS-90 in the cryogenic range. ITS-90 is defined by standard platinum resistance thermometers (SPRTs) from 13.8033 K up to 1234.93 K.

To cover the whole cryogenic range between 13.8033 K and 273.16 K, dealt with in section 3.3.1 of reference [2], capsule-type SPRTs (CSPRTs) are usually employed. CSPRTs are calibrated at eight defining fixed points of the scale, of which six triple points (TPs) and two vapor-pressure points (VPPs). Both LNE-CNAM and INRIM are equipped with cells for the six TPs, namely those of equilibrium hydrogen (e-H2, T90 = 13.8033 K), neon (Ne, T90 = 24.5561 K), oxygen (O2, T90 = 54.3584 K), argon (Ar, T90 = 83.8058 K), mercury (Hg, T90 = 234.3156 K) and water (TPW, T90 = 276.16 K), see Table 1.

The first four TPs are realized in similar facilities, basically two twin isothermal cryostats [START_REF] Ferri | 2 nd Seminar on Low-Temperature Thermometry[END_REF][START_REF] Sparasci | An Adiabatic Calorimeter for the Realization of the ITS-90 in the Cryogenic Range at the LNE-CNAM[END_REF] provided with multiple TP cells. These systems allow measurements to be performed, in a single temperature excursion run, employing the calorimetric method, as recommended in [START_REF] Fellmuth | Guide to the Realization of the ITS-90: Cryogenic Fixed Points[END_REF] for low-temperature fixed points. The method consists in heating the sample through the phase transition under nearly isothermal conditions, by an intermittent input of heat. After each heat pulse, the cell is allowed to come to thermal equilibrium. Details are provided in section 2.1.1 (the reader is also referred to the Appendix of the present paper for details about the overall calibration procedure). The Hg TP is realized in systems which differ widely in the two laboratories. INRIM employs cells immersed in a bath supplying continuous heating [START_REF] Pearce | Guide to the Realization of the ITS-90: Metal Fixed Points for Contact Thermometry[END_REF], while LNE-CNAM uses miniature cells in an isothermal cryostat [START_REF] Sparasci | A new calorimeter for the simultaneous calibration of SPRTs and CSPRTs at the triple point of mercury[END_REF], and realizes the phase transition on the basis of the calorimetric method [START_REF] Fellmuth | Guide to the Realization of the ITS-90: Cryogenic Fixed Points[END_REF]. The TPW is realized in the same way, with quartz sealed cells inside a temperature-controlled bath [START_REF] Peruzzi | Guide to the Realization of the ITS-90: Triple Point of Water[END_REF]. Finally, in both laboratories, the two VPPs of e-H2, near 17.0 K and 20.3 K, see Table 1, are not systematically realized with open cells or a gas thermometer: they are rather transferred with rhodium-iron resistance thermometers (RIRTs) previously calibrated against an interpolating constant-volume gas thermometer (ICVGT), either by the same lab (INRIM) or by another lab -see sections 2.1.2 and 2.2.2.

The comparison described in this paper involves the realization of the ITS-90 between the TP of e-H2 and the TPW (see Table 1). It was carried out by the exchange of a CSPRT (Rosemount 162D, serial number (s/n): 5435) as a transfer standard between the two NMIs, calibrated at LNE-CNAM first, then at INRIM. The comparison not being officially registered in the CIPM 1 or EURAMET 2 databases, a specific protocol has not been defined. Therefore, to ensure measurement comparability, the two laboratories have applied the procedures registered within their respective quality management systems, regularly employed to produce calibration certificates, compliant with the Calibration and measurement capabilities (CMCs) included in the CIPM Mutual Recognition Arrangement (MRA) and available in the Key Comparison Database (KCDB) [START_REF] Kcdb | The BIPM key comparison database[END_REF].

2 Experimental Apparatus and Procedures

Calibration at INRIM

Triple point cells and direct-calibration apparatus below 84 K

The TP cells constituting the Italian National Temperature Standard below 84 K are given with the serial numbers Ec1H2 for the TP of e-H2, Ec2Ne for the TP of Ne, Ec1O2 for the TP of O2 and Ec1Ar for the TP of Ar. The designation Ec refers to element (E) of type c, as developed during the so-called MULTICELLS project [START_REF] Pavese | Temperature: Its Measurement and Control in Science and Industry[END_REF][START_REF] Pavese | Temperature: Its Measurement and Control in Science and Industry[END_REF], the four cells being able to be mounted together on a copper block, allowing a further five thermometers to be put in direct thermal contact. With respect to the e-H2 and Ne cells, information is required regarding their isotopic composition: cell Ec1H2 contains 91.6 mol D / mol H [17] while cell Ec2Ne contains 0.093 36 mol 22 Ne / mol Ne and 0.002 649 mol 21 Ne / mol Ne [START_REF] Pavese | Temperature: Its Measurement and Control in Science and Industry[END_REF]. As regards the calibration of CSPRT-5435 (Transfer standard of the present work) the isotopic corrections, inherent in the reference points, were applied as prescribed in the Technical Annex of the Mise-en-Pratique of the kelvin 1 CIPM: International Committee for Weights and Measures 2 EURAMET: European Association of National Metrology Institutes [START_REF]Technical Annex for the International Temperature Scale of 1990 (ITS-90[END_REF], now after the redefinition of the kelvin, denominated Technical Annex for the International Temperature Scale of 1990 (ITS-90) [START_REF] Steur | Temperature, its Measurement and Control in Science and Industry[END_REF]. The values of the respective corrections for the isotopic effect, in kelvin, were found to be -14 K for e-H2 and -126 K for Ne.

As outcome, the MULTICELLS project produced also an automated data-acquisition system [START_REF] Ferri | 2 nd Seminar on Low-Temperature Thermometry[END_REF] with the software requiring always a control thermometer to set the temperature of the copper block. Since its inception this is a RIRT, designated B191. The other (capsule) thermometers are usually CSPRTs. Thus, the computer-controlled system for direct calibration at the TPs consists of the copper block, housing the four cells and the capsule thermometers (SPRT / RIRT), surrounded by an adiabatic copper shield, whose temperature is further controlled by a RIRT (s/n 10729) and a heater. The role of the adiabatic copper shield is to create the closest approximation of the adiabatic state for the cell. It is enclosed, on its turn, by a shield connected to the second stage of a Gifford-McMahon cryocooler [START_REF] Ferri | 2 nd Seminar on Low-Temperature Thermometry[END_REF]. This shield is temperature-controlled only for the TPs of O2 and Ar in order to supply adequate thermal conditions for the adiabatic shield. Before realizing a TP, the system performs automated checks on thermal capacitances and on the degree of adiabaticity by means of the thermometer B191. Then, a proper plateau realization is started: a series of intermittent heat pulses is applied to the solid TP substance, realizing a series of states of increasing melted fraction (F), see in the Appendix, until the liquid state has been reached. After each heat pulse, when the cell has returned to thermal equilibrium again, the resistances for all the thermometers are measured in sequence using a DC resistance bridge (Measurements International, model 6010T). Depending on the temperature of the TP, the measurement current (1 mA, 2 mA or 5 mA) and the reference resistor (10 Ω or 1 Ω, temperature-controlled in a bath) are chosen in order to maximize the sensitivity of the CSPRT and that of the resistance bridge at the given temperature. The melted fractions F after each heat pulse are calculated taking account of the power applied via the pulse and its duration, the residual heat flux due to the non-ideal adiabaticity and the additional heat generated by the measuring current of the thermometers. In order to disseminate all out such a historical reference, RIRT 232324 is mounted on another devoted cryostat, cooled by a pulse-tube cryocooler (Cryomech, model PT410) which minimizes mechanical vibrations. Here the copper block, housing both the RIRT and the thermometers to be compared (CSPRTs or RIRTs), is enclosed by an adiabatic shield performing the temperature control directly via the 232324 readings. Measurements at the VPP temperatures are still performed via an automated software which pilots an AC resistance bridge (Automatic Systems Laboratories, model F900) connected to a temperaturecontrolled 10 Ω reference resistor. Thermometer currents are selected such that the powers generated by the mounted thermometers differ as little as possible, and thus with little perturbation of the thermal condition of the comparison block during switching.

Overall calibration procedure of the transfer standard

The transfer standard underlying the comparison, CSPRT 5435, was transferred from LNE-CNAM to INRIM without any information about previous calibrations or traceable applications, except for its resistance value at the TPW. The calibration procedure adopted at INRIM was the following: firstly the transfer standard was calibrated at the TPW and at the TP of Hg using a home-made stem-housing conduit, and provided with a copper / stainless steel jacket, to avoid liquid infiltration. In the case of the TPW, the Italian National Temperature Standard, used in this stage, was the cell Hart model 5901, s/n 1322 (Hart Scientific, part of Fluke Corp.), while for the TP of Hg, the home-made cell CRYO-07 was used. The corrections applied to the temperature values due to the depth immersion within the cells were 0.163 mK and -0.891 mK, respectively, while a further correction of 0.077 mK was added to the temperature values measured at the TPW to account for the isotopic composition, as established in [START_REF] Steur | Temperature, its Measurement and Control in Science and Industry[END_REF]; for details see, in particular Table 2, as regards uncertainties correlated with INRIM results and, in general, Section 4.

The measurement at the TPW showed a difference of only -0.057 mK with respect to the value supplied by LNE-CNAM. As the thermometer remained stable after transport, it was then mounted in the cryostat for direct calibration over the temperature range from 13.8033 K up to 83.8058 K, and the whole system was cooled to its minimum (≈ 10 K) using He as exchange gas. The gas was pumped out overnight, and a temperature of about 14 K (only about 0.2 K above the TP of e-H2) was set for the adiabatic shield in order to allow for the ortho-para conversion [START_REF] Fellmuth | Guide to the Realization of the ITS-90: Cryogenic Fixed Points[END_REF] to take place as fast as possible (see the Appendix). Then, the system was cooled down to about 0.5 K below the TP of e-H2 (13.8033 K), and the fully automatic plateau realization was started, taking about 3-4 days to complete. In this way, three plateaus were realized for the TP of e-H2 to confirm the reproducibility and, similarly, three plateaus for each of the other cryogenic TPs (Ne, O2 and Ar) at 24.5561 K, 54.3584 K and 83.8058 K. Reproducibilities, derived from these realizations, were 0.021 mK, 0.027 mK, 0.037 mK and 0.115 mK, for the TPs of e-H2, Ne, O2 and Ar, respectively.

After completion of the third plateau for Ar, the system was allowed to return to room temperature, and the transfer standard (CSPRT 5435) was mounted on the pulse-tube system for the comparison measurements with RIRT 232324, carrying the two VPPs of the ICVGT scale, see the Introduction. The temperatures near 17 K and 20.3 K were regulated by a temperature controller after the system was cooled down to its minimum base temperature (≈ 4 K), the overall measurement process taking about two weeks to complete.

Calibration at LNE-CNAM

Triple point cells and calibration apparatus below 84 K

The TP cells used at LNE-CNAM below 84 K are of a different design but derive, like the INRIM ones, from the same MULTICELLS project described in section 2.1.1. They are the same used in the trilateral comparison [5], identified with the following serial numbers: H202/1 for e-H2, Ne02/1 for Ne, O201/1 for O2, Ar01/1 for Ar. They are assembled to form a solid block where up to four thermometers can be installed. An additional copper block can be mounted under the cell assembly, to allow the fitting of four extra thermometers. No information on isotopic composition is available on e-H2 and Ne cells, thus an extra uncertainty on isotopic composition is included in the calibration uncertainty budget (see tables B2 and B4 in [5]).

A cryostat, based on the Gifford-McMahon cryocooler [START_REF] Sparasci | An Adiabatic Calorimeter for the Realization of the ITS-90 in the Cryogenic Range at the LNE-CNAM[END_REF], similar to that available at INRIM (section 2.1.1), is employed at LNE-CNAM. The cell assembly with the thermometers is placed inside an adiabatic copper shield, whose temperature is controlled by means of a Cernox® thermometer (Lakeshore) and an associated heater. The adiabatic shield is surrounded by a shield connected to the second stage of the cryocooler, whose temperature is controlled with another Cernox® thermometer and an associated heater.

The phase transitions are realized by means of a series of intermittent heat pulses and the thermometers under calibration are measured with an AC resistance bridge (Automatic Systems Laboratories, model F18).

As for INRIM's system, probe currents and temperature-controlled reference resistors are selected to maximize the sensitivity. Reference thermometers are installed in the same cell assembly as the thermometers under calibration and the measurements are performed with the same cryocooler and at the same temperature excursion realized for the TPs measurements. In this way, the reference thermometers are measured also at the TP temperatures, allowing an in-situ check of the stability of their calibration.

Triple point of Hg and associated apparatus

In 2013, LNE-CNAM developed a calorimeter for the simultaneous calibration of long-stem and CSPRTs at the TP of Hg [START_REF] Sparasci | A new calorimeter for the simultaneous calibration of SPRTs and CSPRTs at the triple point of mercury[END_REF]. The difference with most traditional systems [START_REF] Pearce | Guide to the Realization of the ITS-90: Metal Fixed Points for Contact Thermometry[END_REF] is the capability to perform calorimetric realizations of the phase transition, as the apparatus is essentially an isothermal cryostat. Capsule thermometers are installed in a copper block connected to the TP cell and the assembly is surrounded by a thermal shield. The latter is thermally stabilized by another mercury triple point cell mounted above the former, here named "guard cell", which plays a role in sinking the heat flow conveyed by the well of the long-stem SPRT. Heaters are installed on both the TP and the guard cells and the second is also equipped with a control thermometer. The whole system is contained in a vacuum can and immersed in a temperaturecontrolled bath. Mercury is preliminarily frozen in both cells, then the bath temperature is slightly raised above the TP temperature of Hg (typically by about 10 mK) and the TP of Hg in the guard cell is induced by applying a series of heat pulses through its heater. Heating of the guard cell is stopped when the fraction of melted Hg is around 30% of the total: at this point, the ongoing phase transition in the guard cell stabilizes the shield temperature (reducing temperature oscillations to less than 1 mK) and sinks any heat arriving from the piping and the central well housing the long-stem SPRT. Afterwards, heat pulses are applied to the main TP cell: the phase transition is realized in the same way as for cryogenic TPs; the melting plateau lasts generally 4 to 5 days. The Hg apparatus of LNE-CNAM is shown in Figure 1.

The transfer standard: calibration procedure

As mentioned in section 2.1.3, the transfer standard CSPRT 5435 was calibrated at LNE-CNAM before sending it to INRIM. All the TP cells used were part of the French National Temperature Standard batch.

First, the thermometer was calibrated at the TPW using a home-made adaptor stem, into the cell Hart model 5901, s/n 1422 (Hart Scientific). Then, the thermometer was calibrated in the TP cell of Hg, s/n 08144 (home-made, described in 2.2.3). After this step, the stability of the thermometer was checked at the TPW and no significant shift was observed with respect to previous measurements. In all these measurements, self-heating was evaluated by means of the same procedure as followed by INRIM, i.e. the thermometer resistance was extrapolated to zero current from measurements performed at 1 mA and 1•√2 mA.

Later on, CSPRT 5435 was installed in the low-temperature cryostat for fixed points, inside a cell assembly composed by the cells H202/1, Ne02/1, O201/1 and Ar01/1, referred to earlier in section 2.1.1. The cryostat was cooled down to the base temperature (below 10 K) with exchange gas, then the gas was removed, and the temperature was set to 14 K for three weeks, to allow the ortho-para conversion of H2. Then, the system was cooled down to about 0.5 K below the TP temperature of e-H2 to freeze the sample and an automatic plateau realization was initiated, taking about 4 days to complete. Self-heating was evaluated on each thermometer, from measurements performed at 5 mA and 5•√2 mA on CSPRTs, and 1 mA and 1•√2 mA on RIRTs. All the thermometers installed in the cell assembly were cyclically measured with a scanner, including the transfer standard CSPRT 5435 and the two reference thermometers RIRT 229071 and CSPRT B398. The e-H2 plateau was repeated three times. A similar measurement procedure was employed at higher temperatures, to realize the TPs of Ne, O2 and Ar. At the TPs of O2 and Ar, currents of 2 mA and 2•√2 mA were supplied on CSPRTs, and 1 mA and 1•√2 mA on RIRTs.

After the e-H2 realization, the temperature of the cell assembly was raised to 17.0332 K. RIRT 229071 was used as reference sensor, to control the temperature of the cell assembly. It was disconnected from the main resistance bridge, exclusively connected to an additional AC resistance bridge and powered with 1 mA, in order to be continuously measured and allow the control of the assembly temperature. The second reference thermometer, CSPRT B398, was kept connected to the main resistance bridge, and so it was cyclically measured with the scanner, and compared with the RIRT 229071. CSPRTs were all measured using 5 mA, but self-heating evaluations were not performed, as the additional heat produced by the thermometers when they were powered with 5•√2 mA would have significantly changed the temperature setpoint of the cell assembly. Thus, self-heating was inferred from measurements at the e-H2 and Ne TPs, with a standard uncertainty of around 0.5 mK. The comparison at 17.0332 K was repeated three times, then the cryostat temperature was raised to 20.2687 K, applying the same procedure used at 17.0332 K.

Measurements were analyzed after the realization of the experiments. The correlated uncertainty values considered, dealing with LNE-CNAM only, can be found in Table 3 of Section 4. At this stage it was noticed that the resistance of the reference thermometer RIRT 229071 had shifted by -1,73 [START_REF] Steur | Temperature: Its Measurement and Control in Science and Industry[END_REF] mΩ at the TPs of e-H2 and Ne, with respect to its previous calibration done at LNE-CNAM. Such a resistance shift corresponded to -7.36 mK at 17.0332 K and -8.58 mK at 20.2687 K. Data from the second reference thermometer B398, which didn't show any instability at the TPs of e-H2 and Ne, confirmed these shifts and the necessity to introduce corrections on the readings of RIRT 229071. Temperature corrections corresponding to the aforementioned shifts were applied to the calibration of the CSPRT 5435 at the two VPPs realized at LNE-CNAM. Standard uncertainties associated to these corrections were evaluated as 0.98 mK at 17.0332 K and 1.14 mK at 20.2687 mK.

After the realization of the fixed points below 84 K, the stability of the CSPRT 5435 was checked again at the TPW, and no significant difference was found with respect to previous measurements (less than 20 µK).

Results

All the procedures applied to carry out measurements and calculate comparison results are those regularly registered in the quality management systems of LNE-CNAM and INRIM, which ensure international traceability and compliance with the CIPM MRA, see Introduction. A consequence of this choice is that measurement uncertainties cannot be lower than those declared by each laboratory as CMCs, hereinafter referred to as uMRA (with a coverage factor k = 1, where the coverage factor refers to the confidence level, in this case, approximately 68%). However, they might be higher if the transfer standard shows instability or poor quality. To limit this risk, LNE-CNAM selected CSPRT 5435 in the batch of its most suitable CSPRTs: the choice revealed to be appropriate, as neither LNE-CNAM nor INRIM had to introduce any additional uncertainty to account for possible CSPRT quality lack. As shown in the following sections, the agreement between INRIM and LNE-CNAM is good at all fixed points between 13.8033 K and 273.16 K. In addition to the CMC uncertainties, INRIM and LNE-CNAM evaluated their "best" standard measurement uncertainties ubest (k = 1) which, at some fixed points, might be lower than the CMC ones (see Section 4 for details). These results are not associated with the CMCs and may be considered as possible improved uncertainty budgets that may replace CMCs in the future.

Table 1 summarizes the overall results of the calibrations performed at INRIM and LNE-CNAM on the basis of the CSPRT 5435 transfer standard. T90 values are the fixed point temperatures specified in the ITS-90 for the range 3.3.1, see Introduction, including the two VPP temperatures as defined in the scale. W ratios are obtained by INRIM (labelled "i") and LNE-CNAM (labelled "j") according to equation (7) in the ITS-90 [2], i.e. W(T90) = R(T90) / R(273.16 K), where R are resistance values corrected for all the effects mentioned in Section 2. Both uMRA and ubest standard uncertainties are reported here directly in millikelvins with a coverage factor k = 1. dT/dW are the mean sensitivity values of the thermometer calculated at each fixed point from the W values, computed with the respective conversion software according to the deviation function [START_REF] Sparasci | A new calorimeter for the simultaneous calibration of SPRTs and CSPRTs at the triple point of mercury[END_REF] in [2], while dTij are the temperature differences between the two laboratories, computed as dTij = (dT/dW)•(Wi -Wj). Lastly, the degree of equivalence, d0.95, between the two NMIs is calculated on the basis of the expression [25] Globally, ubest uncertainties are evaluated in the same way as uMRA. They might be lower than uMRA because they take into account some procedural and technological improvements related to the new calibration facilities introduced in the two laboratories, since the last key comparison or the last CMC review. Table 2 shows that INRIM is able to substantially reduce its uncertainties in the realization of the TPs of e-H2, Ne and O2, with respect to its current CMCs. The improvement is on the one hand the result of the employment of the new automated calibration facility [START_REF] Ferri | 2 nd Seminar on Low-Temperature Thermometry[END_REF], introduced at INRIM after CCT-K2 (see Introduction). Such a new calorimeter provides a well-controlled thermal environment and reduces repeatability uncertainty in measurements. On the other hand, the studies carried out on the isotopic composition effect on the TP temperatures of e-H2 [17] and Ne [START_REF] Pavese | Temperature: Its Measurement and Control in Science and Industry[END_REF] allow further uncertainty reductions on these two points. LNE-CNAM, instead, has already recently revised its CMCs after the adoption of the new cryostats described in [START_REF] Sparasci | An Adiabatic Calorimeter for the Realization of the ITS-90 in the Cryogenic Range at the LNE-CNAM[END_REF] and [START_REF] Kcdb | The BIPM key comparison database[END_REF], which explains why its ubest and uMRA values are nearly the same. The only exception is at temperatures close to 17 K and 20 K, where ubest is roughly half of uMRA. The reason is that uMRA values were determined at LNE-CNAM with a liquid-helium cooled cryostat characterized by poor adiabaticity, especially below 24 K, which introduced large thermal uniformity uncertainties. Conversely, ubest are the uncertainties obtained in the new cryostat [START_REF] Sparasci | An Adiabatic Calorimeter for the Realization of the ITS-90 in the Cryogenic Range at the LNE-CNAM[END_REF], where thermal uniformity has been substantially improved thanks to the use of a cryogen-free cryocooler.

Conclusion

A comparison has been performed at all the cryogenic fixed points of the range 3.

  Finally, the measured resistance values (reduced to zero current) of the CSPRT are plotted against the values 1/F and extrapolated to F = 1, see Figure A.4 in the Appendix. 2.1.2 Vapor-pressure points of e-H2 and comparison-calibration apparatus between 4 K and 27 K Following the prescriptions of the ITS-90, a CSPRT calibration for the range dealt with in section 3.3.1 of reference [2], the full range from 13.8033 K to 273.16 for CSPRTs at cryogenic temperatures, needs two additional calibration points compared to those required by the three intermediate sub-ranges 3.3.1.1, 3.3.1.2 and 3.3.1.3: one close to 17.0 K and another close to 20.3 K. Explicitly citing ITS-90: "These last two may be determined either: by using a gas thermometer as described in Sect. 3.2, in which case the two temperatures must lie within the ranges 16.9 K to 17.1 K and 20.2 K to 20.4 K, respectively; or by using the vapour pressure-temperature relation of equilibrium hydrogen (omitted)". In the past, IMGC (now INRIM) has realized the ICVGT (see Introduction) as prescribed by the ITS-90 [21-23]. The INRIM RIRT labelled 232324 carries this ICVGT scale and the International Comparison Euramet.T-K1 [24] corroborates the results. This scale was transferred in recent years to as many RIRTs as possible, in order to reduce the risk of losing the calibration of this single thermometer, RIRT 232324. Besides, thanks to a recent Euramet approval [14] of a CMC regarding the calibration by comparison of CSPRTs in the 4 K -27 K range, the two VPPs can now be transferred directly via the RIRT 232324, thus allowing easier comparisons between different realizations of the scale even down to 4 K.

  INRIM performed VPP measurements at T17K,INRIM = 17.035 K and T20K,INRIM = 20.27 K, while LNE-CNAM measured VPPs at T17K,LNE-CNAM = 17.0332 K and T20K,LNE-CNAM = 20.2687 K (see sections 2.2.2 and 2.2.4). All these temperature values fall inside the ranges identified in the ITS-90 [2] and enable valid realizations of the ITS-90 itself. However, to allow a direct comparison between INRIM and LNE-CNAM results, INRIM had to scale its measured values, to produce computed calibration values at T17K,LNE-CNAM and T20K,LNE-CNAM. In particular, two quantities R17K = (T17K,INRIM -T17K,LNE-CNAM)•dR/dT17K and R20K = (T20K,INRIM -T20K,LNE-CNAM)•dR/dT20K were subtracted respectively from the resistances measured by INRIM at T17K,INRIM and T20K,INRIM, with dR/dT17K and dR/dT20K being the sensitivity coefficients of the CSPRT. As for the measurements at the other fixed points, the self-heating of the CSPRT was always taken into account by measuring each time the thermometer resistance at x mA and x•√2, then, by extrapolation to zero current. Finally, after the comparison, the transfer standard was calibrated one last time at the TPW by means of the cell Hart model 5901C-Q, s/n1015 (Hart Scientific), as an internal stability check, resulting in no significant shift.

2. 2 . 2

 22 Vapor-pressure points of e-H2 LNE-CNAM usually realizes calibration of thermometers close to 17.0 K and 20.3 K by comparison with one or more reference thermometers. In this case the temperatures were 17.0332 K and 20.2687 K. The batch of reference thermometers consists of four RIRTs and three CSPRTs calibrated by other NMIs and three additional RIRTs calibrated at LNE-CNAM by comparison with the former. For this comparison, RIRT 229071 and CSPRT B398 were used as reference thermometers. The first was calibrated at LNE-CNAM by comparison with RIRTs B115 (NIST calibration) and B188 (NPL calibration), while the second was calibrated at NPL.

3 . 1

 31 of the ITS-90 (see Introduction), from 13.8033 K up to 273.16 K, between the temperature laboratories of LNE-CNAM and INRIM, using a CSPRT provided by LNE-CNAM as transfer standard. The (small) temperature differences found are fully compatible with the combined uncertainties of their respective CIPM MRA CMCs. In addition, both NMIs provided their best uncertainty values, which showed good agreement at all the fixed points and are, therefore, worth to be reported in this paper. To further assess such best measurements uncertainties, LNE-CNAM and INRIM are planning a new comparison involving an exchange of fixed point cells, thus adding solidity to the present comparison.

Figure 1 :Figure 2 Figure 3

 123 Figure 1: Layout of the apparatus for the mercury triple point developed at LNE-CNAM

  : MRA), or up with ubest values (up,best), see Table1. The results are displayed in Figure2and Figure3for up,MRA and up,best, respectively. In both cases LNE-CNAM and INRIM measurements agree within the combined standard uncertainties for each fixed point in the range. When considering MRA uncertainties, the degree of equivalence, d0.95, is comprised between 0.78 mK and 1.63 mK if direct calibrations at the TPs are performed, whereas it goes up to about 9 mK at the VPPs calibrations realized by comparison. The latter is found to decrease by about 3 mK if best uncertainties are considered instead, with the degree of equivalence at the TPs comprised between 0.39 mK and 1.53 mK. As somehow predictable, however, these results confirm qualitatively, in the end, the lower quality of calibrations achieved by comparisons with respect to the ones obtained by direct realizations of the fixed points. Comparable uncertainties can only be obtained

	.	≈	+ • 1.645 + 0.3295 •	-4.05	/	,
	where
	= 0.283 + 0.717 • 1.96 + 0.042 • 1.96 •	-0.399	/	,
	assuming infinite degrees of freedom (a numerical approximation sufficient for all practical purposes), and
	up is the combined standard uncertainty of the two laboratories, either obtained by combining up with uMRA
	values (up,using the vapour-pressure -temperature relation of hydrogen directly, requiring however a dedicated
	apparatus.
	4 Estimated Uncertainties
	Tables 2 and 3 list the uncertainty budgets of INRIM and LNE-CNAM, respectively, on the calibrations of
	CSPRTs in the range 3.3.1 of the ITS-90, see Introduction, with details given for each fixed point on the
	different uncertainty components. Only "best" uncertainty budgets ubest are reported here, as information on
	uMRA can be retrieved from the KCDB database [14]. Combined ubest standard uncertainties are reported in
	bold at the bottom of each table, next to uMRA (k = 1) values.

Table 1

 1 Calibration results obtained for the CSPRT Rosemount 162D s/n 5435 at INRIM and LNE-CNAM

	INRIM (i)	LNE-CNAM (j)

Table 2

 2 Uncertainty budget of INRIM for CSPRTs calibrations at the fixed points of the ITS-90 range 3.3.1

	Uncertainty components	Estimate	TP e-H2	VPP 17 K VPP 20.3 K	TP Ne	TP O2	TP Ar	TP Hg	TPW
	Fixed point realization (including isotopic effects)	Type B	0.06			0.03	0.05	0.05	0.06	0.02
	Resistance bridge linearity	Type B	0.01			0.001	0.003	0.003	0.01	0.01
	Agreement between reference resistors Rs	Type B	0.03			0.01
	Stability of Rs temperature	Type B	0.03			0.004	0.002	0.001	0.001	0.001
	Self-heating	Type B	0.01			0.01	0.01	0.01	0.01	0.01
	Resistance bridge reading	Type A	0.08			0.06	0.04	0.02	0.01	0.01
	SD RIRT 232324 (comparison)	Type B		0.75	0.75
	Fit, interpolation and resistance measurements (comparison)	Type A		0.20	0.20
	Combined ubest/mK (k = 1)		0.10	0.78	0.78	0.07	0.06	0.05	0.06	0.02
	uMRA/mK (k = 1)		0.18	0.8	0.8	0.15	0.13	0.07	0.06	0.05

Table 3

 3 Uncertainty budget of LNE-CNAM for CSPRTs calibrations at the fixed points of the ITS-90 range 3.3.1

	Uncertainty components	Estimate	TP e-H2	VPP 17 K VPP 20.3 K	TP Ne	TP O2	TP Ar	TP Hg	TPW
	Triple point value	Type B	0.24		0.10	0.21	0.18	0.22	0.03

Acknowledgments

This work was supported by the European Metrology Programme for Innovation and Research (EMPIR) Joint Research Project 18SIB02 Real-K "Realising the redefined kelvin" and as part of an International Technical Cooperation in the framework of the Joint Research Laboratory for Fluid Metrology Evangelista Torricelli. The authors want to thank Roberto Gavioso, Daniele Madonna Ripa and Laurent Pitre for their assistance and helpful suggestions and, in particular, Domenico Giraudi, Roberto Dematteis, Giuseppina Lopardo from INRIM and Catherine Martin from LNE-CNAM for the measurements at the triple points of water and mercury.

Appendix

As a guide for the reader's eye, the main steps involved in the direct-calibration of CSPRTs are summarized in the following figures as regards the realization of the triple point of equilibrium hydrogen, which are in this case: the ortho-para conversion (


Keywords: accumulation rates, retro-foreland, Pyrenees, Aquitaine Basin, Bay of Biscay, Cenozoic

Sediment accumulation rates in foreland basins results from a complex interplay between surface and deep processes in both the exhumed relief domain and sedimentary basins. The growth and decay of a mountain belt during orogenic and post-orogenic phases have been largely studied thanks to thermochronological and structural studies. The sedimentary response of the orogenic phases in the preserved sediments of the surrounding basins is well known in terms of sedimentary filling patterns and architecture, but much less better quantified.

Here, we performed a measurement of the siliciclastic sediment volumes of the Pyrenean retro-foreland basin -the Aquitaine Basin and the Bay of Biscay during Cenozoic times -for a better understanding of the erosion and the sediment transfer and deposition during the convergence (syn-orogenic) to post-convergence (post-orogenic) periods of the Pyrenees Mountain. The measurement of the compacted siliciclastic sediment is based on sediment thickness (isopach) maps of known lithologies, derived from the interpretation of 40 000 kms of seismic profiles.

Thanks to the siliciclastic sediment volumes quantification and a well-known retro-foreland basin tectono-sedimentary evolution, we bring quantitative results as:

(1) The amount of preserved sediments is of 51 500 ± 16 800 km 3 for the Cenozoic.

(2) The siliciclastic sediment rate curve during Cenozoic shows two major increase around 26.0 Ma and 2.5 Ma. The 26.0 Ma increase is clearly related to the erosion of the Pyrenees of tectonic origin. The major 2.5 Ma one would be mainly related to a climatic forcing.

(3) The mass balance between the Aquitaine Platform and the deepest domains change through time in favour of the deep domain. This might be explained by the ratio between subsidence that created accommodation space and the sediments feed by the mountain belt and stored in the Aquitaine Platform.

Introduction

The growth and decay of mountain belts reliefs result from feedbacks between convergence rates, surface processes [START_REF] Beaumont | Erosional control of active compressional orogens[END_REF][START_REF] Willett | Orogeny and orography: the effects of erosion on the structure of mountain belts[END_REF] and isostatic response [START_REF] Molnar | Some simple physical aspects of the support, structure, and evolution of mountain belts[END_REF][START_REF] Watts | Isostasy and Flexure of the Lithosphere[END_REF]. The topography of a mountain belt is first built by continental crust thickening during convergence, generating loading on the lithosphere and its downward deflection at the origin of the surrounding foreland basins and their vertical motion [START_REF] Beaumont | Foreland basins[END_REF][START_REF] Allen | Basin analysis: Principles and application to petroleum play assessment[END_REF]. Topographic evolution of the mountain belt is also influenced by climate which can modify the erosion by surface processes (e.g. Whipple, 1999). Finally, the base level variations in the foreland basins may play a dominant role, on piedmont dynamics, in preserving reliefs (base level rise with emplacement of endorheism, [START_REF] Babault | Origin of the highly elevated Pyrenean peneplain[END_REF] or enhancing its incision (base level fall by major capture for instance, see [START_REF] Burbank | Tectonic geomorphology[END_REF] The estimation of denudation, i.e. the amount of eroded rocks, through time and its controls by lithospheric deformation and/or climate (precipitation) are of primary importance for understanding (1) the topographic growth and decay of mountain belts, but also (2) the volumes and lithologies of the sediments produced and transferred to the surrounding basins.

The quantification of the denudation of a mountain belt is mainly based on low temperature chronology (e.g. fission track and (U-Th)/He on apatite and zircons -ZFT, AFT, ZHe, AHe) that provides a cooling history classically converted into exhumation with using thermal numerical models [START_REF] Braun | Pecube: A new finite-element code to solve the 3D heat transport equation including the effects of a time-varying, finite amplitude surface topography[END_REF] for instance, [START_REF] Ketcham | Forward and inverse modeling of low-temperature thermochronometry data[END_REF][START_REF] Gallagher | Markov chain Monte Carlo (MCMC) sampling methods to determine optimal models, model resolution and model choice for Earth Science problems[END_REF]. The sediment production (volumes, petrography and grain-size) was performed on several foreland basins [START_REF] Molnar | Late Cenozoic uplift of mountain ranges and global climate change: chicken or egg?[END_REF][START_REF] Einsele | Sedimentary basins: evolution, facies, and sediment budget[END_REF][START_REF] Najman | Reconstructing early Himalayan tectonic evolution and paleogeography from Tertiary foreland basin sedimentary rocks, northern India[END_REF]Goodbred and Kuelh, 2000;[START_REF] Schlunegger | Climate, exposed source-rock lithologies, crustal uplift and surface erosion: a theoretical analysis calibrated with data from the Alps/North Alpine Foreland Basin system[END_REF][START_REF] Garzanti | The Himalayan Foreland Basin from collision onset to the present: A sedimentary-petrology perspective[END_REF]. In the Pyrenean domain, the P. Allens's group has carried out numerous studies on these thematic, focus on the southern side (e.g. [START_REF] Michael | The functioning of sediment routing systems using a mass balance approach: Example from the Eocene of the southern Pyrenees[END_REF]Michael et al., , 2014 a,b; a,b;[START_REF] Armitage | Sediment transport model for the Eocene Escanilla sedimentrouting system: Implications for the uniqueness of sequence stratigraphic architectures[END_REF].

The quantification of the siliciclastic sediment volume (sink) in foreland basins was first performed at mountain-scale in the Alps [START_REF] England | Metamorphic pressure estimates and sediment volumes for the Alpine orogeny: an independent control on geobarometers? Earth Planet[END_REF][START_REF] Kuhlemann | Post-collisional sediment budget of circum-Alpine basins (Central Europe)[END_REF][START_REF] Kuhlemann | Post-collisional sediment budget history of the Alps: tectonic versus climatic control[END_REF], but most of them concerns the latest deposition stages found in the ultimate sink: the passive margin laterally connected to the foreland basins. This is the case for Asian mountains [START_REF] Métivier | Mass accumulation rates in Asia during the Cenozoic[END_REF][START_REF] Clift | Controls on the erosion of Cenozoic Asia and the flux of clastic sediment to the ocean[END_REF] or Rocky Mountains and the margins of the Gulf of Mexico [START_REF] Galloway | Sediment accumulation rates in time and space: Paleogene genetic stratigraphic sequences of the northwestern Gulf of Mexico basin[END_REF][START_REF] Galloway | History of Cenozoic North American drainage basin evolution, sediment yield, and accumulation in the Gulf of Mexico basin[END_REF]. They all show an increase of the sedimentation rates up to today, a critical point discussed by P. Molnar [START_REF] Molnar | Late Cenozoic uplift of mountain ranges and global climate change: chicken or egg?[END_REF][START_REF] Molnar | Late Cenozoic increase in accumulation rates of terrestrial sediment: How might climate change have affected erosion rates?[END_REF] that might be related to global climate cooling (e.g. [START_REF] Herman | Plio-Pleistocene increase of erosion rates in mountain belts in response to climate change[END_REF] and/or large erosion/recycling of the foreland deposits (Schlunnegger and Mosar, 2011;[START_REF] Leroux | High-resolution evolution of terrigenous sediment yields in the Provence Basin during the last 6 Ma: relation with climate and tectonics[END_REF], linked frontal accretion, climate variations and drainage network reorganization. Thus, the volumes distribution (storage, transfer, recycling) between the foreland and the final sink at different stages of mountain belt evolution have not been fully explored since the synthesis of [START_REF] Hinderer | From gullies to mountain belts: a review of sediment budgets at various scales[END_REF] We propose in this study to measure the siliciclastic sediment volumes in a retroforeland basin where limited frontal accretion allows a more complete preservation of syntectonic deposits -the Aquitaine Basin and the Bay of Biscay during Cenozoic times for a better understanding of the erosion, the sediment transfer and deposition during the convergence to post-convergence periods of the Pyrenees Mountains and discuss at the first order the tectonic and climatic control factors. The measurement of the compacted siliciclastic sediment volumes (for a solid rocks equivalence) are based on sediment thickness (isopach) maps of known lithologies, built from an extensive dataset of seismic lines interpreted using the principles of seismic stratigraphy and dated on wells [START_REF] Ortiz | Sediment routing system and sink preservation during the post-orogenic evolution of a retro-foreland basin: The case example of the North Pyrenean (Aquitaine, Bay of Biscay) Basins[END_REF].

Geological setting

The North Pyrenean retro-foreland and its lateral deep area of ultimate sediment deposition -the deep Bay of Biscay Basin -is segmented into three geographical-geological units (Fig. 1): (1) upstream, bounded westward by the Pamplona transfer zone, the Aquitaine Platform (i.e. the modern onshore Aquitaine Basin and its shelf), (2) the Landes Plateau, bounded westward by the Santander "soft" transfer zone, is a step (1000-1800 m deep) bounded by slopes and canyons (Capbreton, Cap-Ferret) and (3) the deep Bay of Biscay (4000-4500 m deep).

Tectonic, relief and exhumation evolution of the Pyrenees

The Pyrenees Mountains are a collisional belt bringing Eurasian lithosphere over the Iberian lithosphere (e.g. [START_REF] Roure | ECORS deep seismic data and balanced cross sections: Geometric constraints on the evolution of the Pyrenees[END_REF][START_REF] Muñoz | Evolution of a continental collision belt: ECORS-Pyrenees crustal balanced cross-section[END_REF]. Both Pyrenees and Basque-Cantabrian Mountains result from the inversion and compression of the Albian hyperextended Eurasian lithosphere (e.g. [START_REF] Fabriès | Evolution of the upper mantle beneath the Pyrenees: evidence from orogenic spinel lherzolite massifs[END_REF][START_REF] Fabriès | Petrogenetic evolution of orogenic lherzolite massifs in the central and western Pyrenees[END_REF][START_REF] Lagabrielle | Submarine reworking of exhumed subcontinental mantle rocks: field evidence from the Lherz peridotites, French Pyrenees[END_REF][START_REF] Jammes | Tectonosedimentary evolution related to extreme crustal thinning ahead of a propagating ocean: Example of the western Pyrenees[END_REF][START_REF] Lagabrielle | Mantle exhumation, crustal denudation, and gravity tectonics during Cretaceous rifting in the Pyrenean realm (SW Europe): Insights from the geological setting of the lherzolite bodies[END_REF][START_REF] Masini | The tectonosedimentary evolution of a hyper-extended rift basin: the example of the Arzacq--Mauléon rift system (Western Pyrenees, SW France)[END_REF][START_REF] Clerc | Exhumation of subcontinental mantle rocks: evidence from ultramafic-bearing clastic deposits nearby the Lherz peridotite body, French Pyrenees[END_REF][START_REF] Clerc | Basement--Cover decoupling and progressive exhumation of metamorphic sediments at hot rifted margin. Insights from the Northeastern Pyrenean analog[END_REF][START_REF] Ducoux | The Nappe des Marbres unit of the Basque-Cantabrian Basin: the tectono-thermal evolution of a fossil hyperextended rift basin[END_REF][START_REF] Saspiturry | Symmetry vs. asymmetry of a hyper-thinned rift: example of the Mauléon Basin (Western Pyrenees, France)[END_REF][START_REF] Ducoux | Basement-cover decoupling during the inversion of a hyperextended basin: Insights from the Eastern Pyrenees[END_REF], Tugend et al., 2014). The relative motion of Eurasia and Africa plates controlled the orogeny: the compression started at the time of convergence of the two plates, i.e. at the end of the Santonian (83.6 Ma, Schettino and Turco, 2011) and ended around the Oligocene-Miocene boundary (chron 6c, [START_REF] Roest | Kinematics of the plate boundaries between Eurasia, Iberia, and Africa in the North Atlantic from the Late Cretaceous to the present[END_REF]Srivastava, 1991, Macchiavelli et al., 2017).

Thermochronological data also document the early mountain building with a cooling phase at around 70 Ma [START_REF] Whitchurch | Sediment routing system evolution within a diachronously uplifting orogen: Insights from detrital zircon thermochronological analyses from the South-Central Pyrenees[END_REF][START_REF] Beamud | Magnetostratigraphy and detrital apatite fission track thermochronology in syntectonic conglomerates: constraints on the exhumation of the South-Central Pyrenees[END_REF][START_REF] Mouthereau | Placing limits to shortening evolution in the Pyrenees: Role of margin architecture and implications for the Iberia/Europe convergence[END_REF][START_REF] Ternois | Thermochronological evidence of early orogenesis, eastern Pyrenees, France[END_REF][START_REF] Waldner | Central Pyrenees mountain building: constraints from new LT thermochronological data from the Axial Zone[END_REF]. During Cenozoic, several studies resolve the increase of exhumation during late Eocene-Oligocene times [START_REF] Fitzgerald | Asymmetric exhumation across the Pyrenean orogen: implications for the tectonic evolution of a collisional orogen[END_REF][START_REF] Sinclair | Asymmetric growth of the Pyrenees revealed through measurement and modeling of orogenic fluxes[END_REF][START_REF] Gibson | Late-to post-orogenic exhumation of the Central Pyrenees revealed through combined thermochronological data and modelling[END_REF][START_REF] Jolivet | Thermochronology constraints for the propagation sequence of the south Pyrenean basement thrust system (France-Spain)[END_REF]Gunnel et al., 2009;[START_REF] Metcalf | Thermochronology of a convergent orogen: Constraints on the timing of thrust faulting and subsequent exhumation of the Maladeta Pluton in the Central Pyrenean Axial Zone[END_REF][START_REF] Whitchurch | Sediment routing system evolution within a diachronously uplifting orogen: Insights from detrital zircon thermochronological analyses from the South-Central Pyrenees[END_REF][START_REF] Fillon | Post-orogenic evolution of the southern Pyrenees: Constraints from inverse thermo-kinematic modelling of low-temperature thermochronology data[END_REF]Bosch et al., 2016) following an earlier uplift of the eastern range during Middle Eocene times [START_REF] Maurel | The Meso-Cenozoic thermo-tectonic evolution of the Eastern Pyrenees: an 40 Ar/39 Ar fission track and (U-Th)/He thermochronological study of the Canigou and Mont-Louis massifs[END_REF][START_REF] Beamud | Magnetostratigraphy and detrital apatite fission track thermochronology in syntectonic conglomerates: constraints on the exhumation of the South-Central Pyrenees[END_REF][START_REF] Mouthereau | Placing limits to shortening evolution in the Pyrenees: Role of margin architecture and implications for the Iberia/Europe convergence[END_REF][START_REF] Vacherat | Thermal imprint of rift-related processes in orogens as recorded in the Pyrenees[END_REF]2016;[START_REF] Ternois | Thermochronological evidence of early orogenesis, eastern Pyrenees, France[END_REF][START_REF] Whitchurch | Sediment routing system evolution within a diachronously uplifting orogen: Insights from detrital zircon thermochronological analyses from the South-Central Pyrenees[END_REF][START_REF] Waldner | Central Pyrenees mountain building: constraints from new LT thermochronological data from the Axial Zone[END_REF]. Finally, a late Miocene exhumation phase is recorded in the Western Pyrenean Range by several authors [START_REF] Jolivet | Thermochronology constraints for the propagation sequence of the south Pyrenean basement thrust system (France-Spain)[END_REF]Bosch et al., 2016;[START_REF] Fillon | Post-orogenic exhumation in the western Pyrenees: evidence for extension driven by pre-orogenic inheritance[END_REF]

Stratigraphic and tectonic evolution of the Aquitaine Basin and Bay of Biscay deep Basin

Several studies have been carried out on the tectono-stratigraphic evolution of the Aquitaine Basin since the late Cretaceous [START_REF] Brunet | Subsidence history of the Aquitaine basin determined from subsidence curves[END_REF][START_REF] Desegaulx | Tectonic subsidence of the Aquitaine basin since Cretaceous times[END_REF][START_REF] Brunet | Subsidence in the Parentis Basin (Aquitaine, France): Implications of the thermal evolution[END_REF][START_REF] Sztrákos | L'Eocène du Bassin sud-aquitain: lithostratigraphie, biostratigraphie et analyse séquentielle[END_REF][START_REF] Serrano | Évolution du bassin compressif Nord-Pyrénéen au Paléogène (bassin de l'Adour): contraintes stratigraphiques[END_REF][START_REF] Ford | Retro-wedge foreland basin evolution along the ECORS line, eastern Pyrenees, France[END_REF][START_REF] Sztrákos | Révision lithostratigraphique et biostratigraphique de l'Oligocène d'Aquitaine occidentale (France)[END_REF][START_REF] Angrand | Lateral variations in foreland flexure of a rifted continental margin: The Aquitaine Basin (SW France)[END_REF]. They identified two subsiding phases (Latest Santonian -Danian and Thanetian -Oligocene) separated by the so called "Palaeocene quiet period" characterized by a low to near zero subsidence phase [START_REF] Ford | Retro-wedge foreland basin evolution along the ECORS line, eastern Pyrenees, France[END_REF]. The first subsidence phase has been largely influenced by the post rift thermal subsidence because of the short time between the end of the rifting and the beginning of the convergence (around 10 Ma, [START_REF] Angrand | Lateral variations in foreland flexure of a rifted continental margin: The Aquitaine Basin (SW France)[END_REF]. [START_REF] Serrano | Évolution du bassin compressif Nord-Pyrénéen au Paléogène (bassin de l'Adour): contraintes stratigraphiques[END_REF] differentiate two distinct phases in the Western Aquitaine Basin (1) from Palaeocene to Middle Eocene -compressional basin due to lithospheric buckling (mixed system -East-West oriented turbidites and carbonates platform) and (2) from Middle Eocene to Oligocene -foreland stage (progressive continentalization on the eastern part and deltaic progradation toward the West).

Recently, through an extensive bio-and seismic stratigraphy study of both basins, Ortiz et al. ( 2020) identified a set of several discontinuities of tectonic origins (fig. 2). The orogenic period is subdivided into two steps (fig. 2): (1) the dominant lithosphere flexure with the formation of foredeeps up to the uppermost Lutetian and (2) the propagation of the deformation from the orogenic wedge through the basin mainly along salt-controlled thrusts and anticlines locating subbasins. From the basin record point of view, the transition between orogenic and post-orogenic periods is Chattian in age, from 27.1 to 25.2 Ma. This time interval corresponds to the end of thrusting/inversions and a modification of the sediment preservation pattern. The post-orogenic period is also subdivided into two intervals (fig. 2): (1) a sharp decrease of the subsidence rates over the Aquitaine Platform, mainly filled by continental sediments during early Miocene times (25.2-16.4 Ma) and (2) an uplift of the Aquitaine Platform from 16.4 Ma to today characterized by a low-preservation domain up to 10.6 Ma. The main uplift phase occurred at 10.6 Ma and caused a generalized by-pass on the Aquitaine Platform [START_REF] Ortiz | Sediment routing system and sink preservation during the post-orogenic evolution of a retro-foreland basin: The case example of the North Pyrenean (Aquitaine, Bay of Biscay) Basins[END_REF].

Measurement of siliciclastic sediment volumes and rates

The measurement of siliciclastic sediment (sink) volumes is based on four sediment thickness (isopach of preserved sediments) maps: Palaeocene-Eocene (66-33.9 Ma -fig. 3), ) and Pliocene-Pleistocene (5.3-0 Ma -fig. 6). These isopach maps are the products of a seismic stratigraphic analysis of an extensive seismic line dataset (TotalEnergies, BRGM, BSS, fig. 1). This quite low timeresolution is due to the absence of wells in the deep Bay of Biscay and the difficulty to extend timelines from the Aquitaine Platform where several dated wells are available (see [START_REF] Ortiz | Sediment routing system and sink preservation during the post-orogenic evolution of a retro-foreland basin: The case example of the North Pyrenean (Aquitaine, Bay of Biscay) Basins[END_REF]. For each interval the main lithologies proportion is known in the Aquitaine platform and in the Landes Plateau (see [START_REF] Ortiz | Sediment routing system and sink preservation during the post-orogenic evolution of a retro-foreland basin: The case example of the North Pyrenean (Aquitaine, Bay of Biscay) Basins[END_REF] and for the distal part of the Bay of Biscay, we used the studies available in this domain about the Cenozoic sedimentary record [START_REF] Cremer | Approches sédimentologique et géophysique des accumulations turbiditiques: l'éventail profond du Cap-Ferret (Golfe de Gascogne), la série des grès d'Annot (Alpes-de-Haute-Provence) 1 Thèse[END_REF]Iglesias, 2009;[START_REF] Brocheray | 2000 years of frequent turbidite activity in the Capbreton Canyon (Bay of Biscay)[END_REF].

The sediment volumes measured from the isopach maps were later decompacted and the amount of sediments produced in the basin (here mainly carbonates) was removed to get solid rock volumes. We used the protocol and code published by [START_REF] Guillocheau | Quantification and causes of the terrigeneous sediment budget at the scale of a continental margin: A new method applied to the Namibia-South Africa margin[END_REF] that consider uncertainties or ranges for (1) time-depth conversion parameters, (2) absolute ages of the different horizons, (3) carbonate content and (4) surface porosity and e-folding depth for porosity decrease. During Cenozoic times the deep-sea Bay of Biscay fan fed through the Capbreton and Cap-Ferret Canyon by the sediments coming from the Aquitaine Basin has progressively migrated westward [START_REF] Cremer | Approches sédimentologique et géophysique des accumulations turbiditiques: l'éventail profond du Cap-Ferret (Golfe de Gascogne), la série des grès d'Annot (Alpes-de-Haute-Provence) 1 Thèse[END_REF]Iglesias, 2009;[START_REF] Brocheray | 2000 years of frequent turbidite activity in the Capbreton Canyon (Bay of Biscay)[END_REF], our calculation area is evolving accordingly (dashed line on figs, 3,4,5,6). In order to compare the volumes, they will be presented through the evolution of the ratio between Aquitaine Basin volume (VOn) and Bay of Biscay volume (VOff) as follow: ROnOff = VOn/VOff.

Isopach maps: results and interpretation

Paleocene-Eocene (66-33.9 Ma)

The Paleocene-Eocene (66-33.9 Ma -Fig. 3) time interval is characterized by sediment preservation along the North Pyrenean Thrust on the Aquitaine Platform, with three subsiding domains -10-50 km large -filled by 3500 m of sediments accumulated in 32 Ma. Two less subsiding domains were located north of the previous ones and bounded by two ridges with very low accumulation. Few sediments were preserved along the Landes Plateau. In the deep Bay of Biscay, two depocenters occurred south of the South Armorican Margin and north of the Biscay Wedge Front.

Interpretation:

The three subsiding domains correspond to a segmented foredeep [START_REF] Ortiz | Sediment routing system and sink preservation during the post-orogenic evolution of a retro-foreland basin: The case example of the North Pyrenean (Aquitaine, Bay of Biscay) Basins[END_REF] controlled by the inherited structures from the Early Cretaceous rifts history [START_REF] Angrand | Lateral variations in foreland flexure of a rifted continental margin: The Aquitaine Basin (SW France)[END_REF]. These domains are mainly filled during the first orogenic phase (up to uppermost Lutetian) and the small depocenter in the northern part of the ridges correspond mainly to the second orogenic phase, when the deformation is propagated basinward. The two deep depocenters of the Bay of Biscay are disconnected from the Aquitaine Platform and bounded by the inverted extensional structures of the Gascogne Dome Bulge [START_REF] Thinon | Structure profonde de la marge nord-Gascogne et du bassin armoricain[END_REF][START_REF] Thinon | Structure profonde de la marge nord-Gascogne et du bassin armoricain[END_REF]. The first depocenter located in the Armorican subbasin, was fed by sediments coming from the Loire River (fig. 1) or from the Armorican Massif [START_REF] Guillocheau | Histoire géologique du Massif armoricain depuis 140 Ma (Crétacé-Actuel)[END_REF].

Oligocene (33.9-23.03 Ma)

The Oligocene (33.9-23.03 Ma -fig. 4) was a period of more widely distributed sediments accumulation along the three domains. In the Aquitaine Platform depocenters are located (i) on both sides of salt-related controlled thrusts forming anticlines or ridges (Maubourguet-Antin, Audignon) or (ii) along N140° faults (e.g. Téthieu Fault, location on figures 1 and 4). In the south Landes Plateau, north of the Basque-Cantabrian Mountains, a 60 km-large depocenters occurred. In the deep Bay of Biscay, a NW-SE trending depocenter is located south-west of the inverted structures of the Gascogne Dome Bulge and north of the Biscay Wedge Front.

Interpretation: Oligocene is a period during which (1) segmented foredeep was no longer subsident and (2) compressive deformation propagated from the orogenic wedge to the retro-foreland basin along salt decollement levels localizing little subbasins [START_REF] Serrano | Le Crétacé Supérieur-Paléogène du Bassin Compressif Nord-Pyrénéen (Bassin de l'Adour). Sédimentologie, Stratigraphie[END_REF][START_REF] Ortiz | Sediment routing system and sink preservation during the post-orogenic evolution of a retro-foreland basin: The case example of the North Pyrenean (Aquitaine, Bay of Biscay) Basins[END_REF]. The depocenters of the south Landes Plateau may be due to the loading effect of the inverted and thrusted Basque Cantabrian Margin starting at 37 Ma and ending at 28.5 Ma (Gomez et al., 2002). The depocenter of the deep Bay of Biscay is disconnected from the Aquitaine Platform and moderately fed by the erosional product coming from the inversion and deformation of the Cantabrian Margin and the uplift of the Cantabrian Mountains from Late Eocene to Oligocene times [START_REF] Gallastegui | Initiation of an active margin at the North Iberian continent-ocean transition[END_REF][START_REF] Pedreira | Geophysicalpetrological modeling of the lithosphere beneath the Cantabrian Mountains and the North-Iberian margin: Geodynamic implications[END_REF][START_REF] Fillon | Alpine exhumation of the central Cantabrian mountains, northwest Spain[END_REF].

Miocene (23.03-5.3 Ma)

The Miocene (23.03 to 5.3 Ma -fig. 5) recorded a major change in the sediment distribution. The Aquitaine platform was henceforth a place of low sediment preservation (less than 200 m for 17.5 Ma). Most of the sediments were transferred and stored along the Landes Plateau and the deep Bay of Biscay. Two major sediment accumulations were active in the Landes Plateau, (1) to the north, a progradational wedge [START_REF] Ortiz | Sediment routing system and sink preservation during the post-orogenic evolution of a retro-foreland basin: The case example of the North Pyrenean (Aquitaine, Bay of Biscay) Basins[END_REF] Interpretation: The Aquitaine Platform was no longer a significant subsiding domain.

Most of the sediments bypassed to deepest areas: (1) through deltaic progradational wedges on the Landes Plateau, (2) through canyons and at the end of the system (3) as deep-sea fans.

The depocenters located north to the Capbreton canyon correspond to the northern levee of the canyon already active at this period [START_REF] Cremer | Approches sédimentologique et géophysique des accumulations turbiditiques: l'éventail profond du Cap-Ferret (Golfe de Gascogne), la série des grès d'Annot (Alpes-de-Haute-Provence) 1 Thèse[END_REF]Iglesias, 2009[START_REF] Ortiz | Sediment routing system and sink preservation during the post-orogenic evolution of a retro-foreland basin: The case example of the North Pyrenean (Aquitaine, Bay of Biscay) Basins[END_REF].

Progradationnal deltaic wedge accumulate at the head of the Cap-Ferret canyon (western extension of the north Landes Plateau depocenter - [START_REF] Cremer | Approches sédimentologique et géophysique des accumulations turbiditiques: l'éventail profond du Cap-Ferret (Golfe de Gascogne), la série des grès d'Annot (Alpes-de-Haute-Provence) 1 Thèse[END_REF]) and downstream (East of the deep Bay of Biscay depocenter), an erosion domain where the canyon is active. These two canyons domains fed downward, the Cap-Ferret deep-sea fan [START_REF] Cremer | Approches sédimentologique et géophysique des accumulations turbiditiques: l'éventail profond du Cap-Ferret (Golfe de Gascogne), la série des grès d'Annot (Alpes-de-Haute-Provence) 1 Thèse[END_REF]Iglesias, 2009) in the deep Bay of Biscay.

Plio-Pleistocene (5.3-0 Ma)

The Pliocene-Pleistocene (5.3-0 Ma -fig. 6 Interpretation: The Aquitaine Plateau was upstream uplifted and incised by rivers [START_REF] Mouchené | Controls on Quaternary incision of the Northern Pyrenean foreland: Chronological and geomorphological constraints from the Lannemezan megafan, SW France[END_REF][START_REF] Ortiz | Sediment routing system and sink preservation during the post-orogenic evolution of a retro-foreland basin: The case example of the North Pyrenean (Aquitaine, Bay of Biscay) Basins[END_REF]. All the products of erosion are transferred to the deepest domains with by-pass to very low sedimentation along the modern Landes Forest [START_REF] Dubreuilh | Dynamique d'un comblement continental néogène et quaternaire: l'exemple du bassin d'Aquitaine[END_REF]. The prograding sedimentary wedge is now located at the border of the Aquitaine shelf and the two canyons (Capbreton and Cap-Ferret) alternated periods of erosion and deposition [START_REF] Cremer | Approches sédimentologique et géophysique des accumulations turbiditiques: l'éventail profond du Cap-Ferret (Golfe de Gascogne), la série des grès d'Annot (Alpes-de-Haute-Provence) 1 Thèse[END_REF]Iglesias, 2009).

Measurement of the siliciclastic sediment budget: results (fig. 7)

In the deep-sea plain, siliciclastic volume measurements were only performed in the south deep Bay of Biscay Basin, south of the Gascogne Dome Bulge, the sediment located northward (Armorican Subbasin) being fed from the Loire River (fig. 1) and the Armorican Massif (see 4.1). In addition, during Cenozoic times the deep-sea Bay of Biscay fan fed through the Capbreton and Cap-Ferret Canyon by the sediments coming from the Aquitaine Basin is progressively migrating westward [START_REF] Cremer | Approches sédimentologique et géophysique des accumulations turbiditiques: l'éventail profond du Cap-Ferret (Golfe de Gascogne), la série des grès d'Annot (Alpes-de-Haute-Provence) 1 Thèse[END_REF]Iglesias, 2009;[START_REF] Brocheray | 2000 years of frequent turbidite activity in the Capbreton Canyon (Bay of Biscay)[END_REF]. This is the reason why, our calculation area is evolving according to the deep-sea fan location (Figs,3,4,5,6).

The total amount of siliciclastic sediments (Tab. 1, Fig. 7) deposited from the Aquitaine Platform to the south deep Bay of Biscay during Cenozoic times is 51 500 km 3 with an uncertainty of 16 800 km 3 , i.e. 33%.

The four-time intervals here defined, have not the same duration and therefore siliciclastic sedimentation rates had to be used for a comparison between time intervals instead of volumes (Tab. 1, fig. 7). At first order the sedimentation rates are increasing from 535 km 3 /Myr (between 66 and 33.9 Ma) to 3150 km 3 /Myr (from 5.3 to 0 Ma). Oligocene and Pliocene-Pleistocene seems to be significant instants of siliciclastic sediment rates increase.

The siliciclastic sediment budget comparison (Tab. 1, fig. 7) between the onshore (Aquitaine Basin) and offshore (Aquitaine shelf, Landes Plateau, south Bay of Biscay) shows a shift, trough Cenozoic times, from onshore to offshore preferential accumulation since Oligocene-Miocene boundary. The sediment ratio between onshore and offshore (ROnOff) is (i) 25.3 from 66 to 33.9 Ma, (ii) 7.5 from 33.9 to 23.03 Ma, (iii) 0.18 from 23.03 to 5.3 Ma and (iv) 0.01 from 5.3 to 0 Ma.

Discussion on the siliciclastic sediment budget

Volume comparison with South Pyrenean Foreland and others orogenic adjacent basins -The amount of siliciclastic sediments preserved in northern foreland is 51 500 ± 16 800 km 3 for Cenozoic times. A comparison with the sediment volumes of other orogenic systems supposes to get a sediment budget for both sides of the Pyrenees, i.e. including the South Pyrenean Foreland basin. Several studies have been conducted for quantifying the preserved sediment volumes in the South Pyrenean sink (i.e. Ebro and Valencia Basins) [START_REF] Nelson | Estimated post-Messinian sediment supply and sedimentation rates on the Ebro continental margin, Spain[END_REF][START_REF] Garcia-Castellanos | Interplay between tectonics, climate, and fluvial transport during the Cenozoic evolution of the Ebro Basin (NE Iberia)[END_REF][START_REF] Babault | Did the Ebro basin connect to the Mediterranean before the Messinian salinity crisis?[END_REF]Filleaudeau, 2011;Arche et al., 2010;[START_REF] Watts | Crustal structure and the mechanical properties of extended continental lithosphere in the Valencia trough (western Mediterranean)[END_REF]. The Ebro Basin has been under endoreic conditions since 36.2 Ma [START_REF] Costa | Closing and continentalization of the South Pyrenean foreland basin (NE Spain): magnetochronological constraints[END_REF] and then opened towards the Mediterranean Sea between 12 Ma and 7.5 Ma [START_REF] Garcia-Castellanos | Interplay between tectonics, climate, and fluvial transport during the Cenozoic evolution of the Ebro Basin (NE Iberia)[END_REF][START_REF] Fillon | Post-orogenic evolution of the southern Pyrenees: Constraints from inverse thermo-kinematic modelling of low-temperature thermochronology data[END_REF]Garcia-Castellanos and Larrasoana, 2015). The total amount of preserved sediments in the Ebro and Valencia Basin is 260 300 km 3 since 66 Myr. For a better sediment budget on both sides of the Pyrenees, only the sediments coming from the mountain belt should be considered, i.e. the total Cenozoic preserved sediments volumes in the Ebro basin and the Neogene for the Valencia Basin. This corresponds to a range between 78 000 km 3 (Filleaudeau, 2011) and 110 000 km 3 ± 5000 km 3 [START_REF] Garcia-Castellanos | Interplay between tectonics, climate, and fluvial transport during the Cenozoic evolution of the Ebro Basin (NE Iberia)[END_REF] in the Ebro Basin and 92 000 km 3 in the Valencia Basin [START_REF] Garcia-Castellanos | Interplay between tectonics, climate, and fluvial transport during the Cenozoic evolution of the Ebro Basin (NE Iberia)[END_REF]. This gives a total of preserved sediments between 170 000 km 3 and 202 000 km 3 . At the first order, this result shows a factor of four between the northern retroforeland (our study) and the South Pyrenean proforeland.

The first-order estimation of total volume preserved in the Pyrenean adjacent basins (i.e. Aquitaine Basin, Bay of Biscay, Ebro Basin, Valencia Basin) is between 220 000 km 3 and 250 000 km 3 . The total volume of siliciclastic sediments produced by the Alps since Oligocene times is of 890 000 km 3 (220 000 km 3 from the Eastern Alps and 670 000 km 3 from the western ones- [START_REF] Kuhlemann | Post-collisional sediment budget history of the Alps: tectonic versus climatic control[END_REF] i.e. four times more than the Pyrenees. However, for larger orogens the order of magnitude changes with 3.35 10 6 km 3 of sediment produced by the Rocky Mountains on its continental part and stored in the Gulf of Mexico [START_REF] Galloway | History of Cenozoic North American drainage basin evolution, sediment yield, and accumulation in the Gulf of Mexico basin[END_REF] and the 4.95 10 6 km 3 by the western side of the Himalaya and accumulated along of the Indus Delta [START_REF] Clift | Controls on the erosion of Cenozoic Asia and the flux of clastic sediment to the ocean[END_REF].

Volume comparison with Pyrenean thermochronological data -We present here some volumes estimation for the Cenozoic period based on published themrochronology data in the Pyrenees.

-Too few data (AFT and AHe) provide Palaeocene to early Eocene ages to obtain a consistent exhumation trend across the entire Pyrenean range.

-During the late Eocene/lower Oligocene (from 37 to 30 Ma), orogenic exhumation (> 0.5 km/Myr) is recorded in Central and Eastern Pyrenean Massif (Maladetta, Nogueres, Canigou) according to studies from [START_REF] Fitzgerald | Asymmetric exhumation across the Pyrenean orogen: implications for the tectonic evolution of a collisional orogen[END_REF], [START_REF] Gibson | Late-to post-orogenic exhumation of the Central Pyrenees revealed through combined thermochronological data and modelling[END_REF], [START_REF] Fillon | Post-orogenic evolution of the southern Pyrenees: Constraints from inverse thermo-kinematic modelling of low-temperature thermochronology data[END_REF] and Gunnel et al., (2009). These authors modeled an exhumation rate of 1.5 to 4 km/Myr. Considering an average of 2 km/Myr integrated over the whole area (inducing a strong assumption of a continuous constant exhumation) during the period of 35-30 Ma, the eroded volume should be of 50 000 km 3 . This value is very high compared to what has been measured in the Aquitaine Basin during the same period (16 500 km 3 from base Cenozoic to base Oligocene). This volume seems therefore to supply mainly the Ebro basin with a significant increase observed at the base of Oligocene (i.e. 33.9 Ma) (Filleaudeau, 2011).

-Since middle Oligocene times, a moderate exhumation (between 0.1 and 0.5 km/Myr) is proposed by several authors in Western, Central and Eastern massifs of the Pyrenean range (DeFelipe et al., 2019;Bosch et al., 2016;[START_REF] Fillon | Post-orogenic exhumation in the western Pyrenees: evidence for extension driven by pre-orogenic inheritance[END_REF][START_REF] Fitzgerald | Asymmetric exhumation across the Pyrenean orogen: implications for the tectonic evolution of a collisional orogen[END_REF][START_REF] Gibson | Late-to post-orogenic exhumation of the Central Pyrenees revealed through combined thermochronological data and modelling[END_REF]. An average exhumation rate of 0.25 km/Myr across the entire range provides an estimation of 17 500 km 3 for the Middle to Late Oligocene period. This volume is, like during Late Eocene/Lower Oligocene, one order of magnitude higher than what we measure in the Aquitaine Basin. This volume supply mainly the Ebro basin where the Oligocene volumes are very large (around 45 000 km 3 in Filleaudeau, 2011).

-Finally, the important increase of exhumation rate recorded in the Western Pyrenees (see [START_REF] Fillon | Post-orogenic exhumation in the western Pyrenees: evidence for extension driven by pre-orogenic inheritance[END_REF] for the data synthesis and modelling) infers a volume estimation of 2 000 km 3 for the late Miocene period. This quantification is low compared to the volumes of preserved sediments.

We draw attention to the fact that these estimation are produces from an average of the results of modelling data done in 1D and extrapolated on a surface. These volumes based on thermochronological data are probably overestimated.

Age estimation of siliciclastic sediment flux increase from interpreted seismic data

As we mentioned earlier, the low stratigraphic resolution (Palaeocene-Eocene, Oligocene, Miocene and Pliocene-Pleistocene) is due to difficulties to propagate the high resolution age model (established in shallow marine setting in the Aquitaine Platform and Landes Plateau - [START_REF] Ortiz | Sediment routing system and sink preservation during the post-orogenic evolution of a retro-foreland basin: The case example of the North Pyrenean (Aquitaine, Bay of Biscay) Basins[END_REF] across the whole seismic survey in the deep Bay of Biscay Basin and continental Aquitaine series. In order to be more precise about the age of the siliciclastic rate increase during the two key periods (Oligocene and Plio-Pleistocene) and their possible links to climatic or geodynamic event, we performed a 2D quantification on the cross section published in [START_REF] Ortiz | Sediment routing system and sink preservation during the post-orogenic evolution of a retro-foreland basin: The case example of the North Pyrenean (Aquitaine, Bay of Biscay) Basins[END_REF]. This quantification aims at comparing on three different locations (proximal Aquitaine platform -deep Bay of Biscay Basin -progradational wedges in between) the percentage of 2D surface (comprising sediment) normalized on their duration between each high-resolution timeline.

The figure 8 present the results and shows a refined estimate of increase at 26.0 ± 2.0 Ma for Oligocene period and 2.5 ± 0.5 Ma for Pliocene-Pleistocene period.

The 26.0 ± 2.0 Ma increase

The measured Late Oligocene (26.0 ± 2.0 Ma) siliciclastic rate increase could be explained by both a tectonic factor -the accretion of Pyrenees basal units -and a climatic factor -the icehouse-greenhouse transition and the late Oligocene warming [START_REF] Zachos | Trends, rhythms, and aberrations in global climate 65 Ma to present[END_REF].

Tectonic -A Late Eocene to Oligocene/Miocene paroxysm of denudation (37-29 Ma central Pyrenees and 37-20 Ma western Axial Zone) is measured by the numerous thermochronological studies (see references in section 2.1) and by the dated active tectonics mainly in the Southern Pyrenees (Montsec and Sierras exteriores thrust systems associated to Orri and Rialp thrust sheets, see Munoz, 1992[START_REF] Teixell | Crustal structure and orogenic material budget in the west central Pyrenees[END_REF], Vergés et al., 2002and Mouthereau et al., 2014), or in the Jaca Basin cover thrust and associated Gavarnie and more frontal thrusts [START_REF] Labaume | Exhumation sequence of the basement thrust units in the west-central Pyrenees. Constraints from apatite fission track analysis[END_REF]. During late Oligocene time, the retro-foreland is affected by several truncation/erosional surfaces from 27.1 to 25.2 Ma [START_REF] Ortiz | Sediment routing system and sink preservation during the post-orogenic evolution of a retro-foreland basin: The case example of the North Pyrenean (Aquitaine, Bay of Biscay) Basins[END_REF].

During this event, some syn-orogenic deposits are recycled and can be transferred to more distal sink. The observed increasing volumes and increasing export of sediment to the Bay of Biscay is thus contemporaneous with a (long) denudation paroxysm, but also with a more temporally resolved drop of preservation in the foreland which becomes less subsident and might be locally eroded and recycled. The observed modification of source to sink pattern might record combination of two processes, denudation increasing phase and cessation of subsidence in the foreland could explain the increase export toward the final sink and sedimentation rate increase observed in the western Aquitaine Platform part (fig. 4).

Climate -Few palaeoclimatological data dealing with the palaeoprecipitation record are available in the Aquitaine Basin. A palaeobotanical synthesis [START_REF] Dupéron-Laudoueneix | Nouvelle étude de Mesembrioxylon libanoticum Edwards (Conifère du Mésozoïque supérieur) ; intérêts paléogéographique, biostratigraphique et paléoclimatique[END_REF] indicate a cooling expressed by a decrease of the tropical taxon from the Eocene to the Oligocene that corresponds to the Eocene-Oligocene global cooling event (Zachos et al., 2011). This event takes place at 33.9 Ma, thus well before the observed 26 Ma event.

The 26.0 ± 2.0 Ma increase event is contemporary with the Late Oligocene Warming, that correspond to a sustained ca. 6°C global warming [START_REF] Zachos | Trends, rhythms, and aberrations in global climate 65 Ma to present[END_REF]. Warming events (such as PETM) can cause sediment pulses [START_REF] Foreman | Fluvial response to abrupt global warming at the Palaeocene/Eocene boundary[END_REF]. [START_REF] Schlunegger | Climate vs. tectonics: the competing roles of Late Oligocene warming and Alpine orogenesis in constructing alluvial megafan sequences in the North Alpine foreland basin[END_REF] have tested this increase hypothesis in the Alpine Foreland Basin. They focus on the Napf megafan sedimentary evolution in the Alpine foothills during this period of sudden warming. As in our study the period is also a time of increasing exhumation phase in the Alpine mountain [START_REF] Schmid | Geophysical-geological transect and tectonic evolution of the Swiss-Italian Alps[END_REF]. They didn't observe remarkable shift in the water discharge, and they ruled out the hypothesis of sediment rate increase due to the Late Oligocene warming but linked it to tectonic process.

In our case, the Late Oligocene (26.0 ± 2.0 Ma) siliciclastic rate increase is linked to the high erosion rates and lower preservation in the Aquitaine Platform controlled by the orogenic tectonic processes. This increase is also registered in the Ebro basin (Filleaudeau, 2011).

The 2.5 ± 0.5 Ma increase and the long-term volume increase

The change in the rate of siliciclastic sediment supply during Plio-Pleistocene (at 2.5 ± 0.5 Ma) is significant (fig. 8) and sharply accentuates the overall increasing rate trend through Cenozoic times. This confirms for this area, the Hay's curve [START_REF] Hay | Mass-balanced paleogeographic reconstructions[END_REF][START_REF] Hay | Relation of selected mineral deposits to the mass/age distribution of Phanerozoic sediments[END_REF]Wold et Hay, 1990) showing a world-scale increase of the siliciclastic fluxes up to today, interpreted by Molnar [START_REF] Molnar | Late Cenozoic uplift of mountain ranges and global climate change: chicken or egg?[END_REF][START_REF] Molnar | Late Cenozoic increase in accumulation rates of terrestrial sediment: How might climate change have affected erosion rates?[END_REF] as the consequence of the global Earth cooling during Plio-Pleistocene times. [START_REF] Herman | Worldwide acceleration of mountain erosion under a cooling climate[END_REF] further suggest a Plio-Pleistocene (at around 6 Ma) increase in erosion rates and with an acceleration at around 2 Ma that they attribute to the global cooling Pliocene and Pleistocene episodes that enhanced erosion in mountainous glaciated area.

Onshore, the most sensible low-temperature thermochronological data, ((U-TH)/He and Fission tracks on apatites) do not show any Pliocene increase of denudation either in the Pyrenees Mountains (e.g. Bosch et al., 2016) or in the French Massif central (T. François, personal communications). The youngest cooling episode is recorded at around 10 Ma (Late Miocene) in the western axial zone and no basin erosion > 1.5 km could be retrieved in the Aquitaine Basin for the last 20 Myrs [START_REF] Fillon | Post-orogenic exhumation in the western Pyrenees: evidence for extension driven by pre-orogenic inheritance[END_REF], except in easternmost Aquitaine Basin (Corbières area) Al [START_REF] Reda | Thermal record of the building of an orogen in the retro-foreland basin: Insight from basement and detrital thermochronology in the eastern Pyrenees and the north Pyrenean basin (France)[END_REF] althought this denudation event is temporally poorly resolved between 20 and 5 Ma, this event is attributed by the authors to early Miocene and opening of the Gulf o Lion.

With these observations, several hypothesis have yet to be tested: (1) a climate effect on the intensity and pattern of erosion, with the effect of glaciations and change of the pattern of erosion, from widely distributed before 5.3 Ma to localized in valleys after with a greater climate effect from 2 Ma, which could be associated to (2) an "underestimated" significant reerosion of previously deposited sediments in the Aquitaine Basin ("cannibalization") and (3) lateral supply of sediments from other sources in the deep-sea domain under the action of deep-sea currents (Le Danois Contourite Depositional System due to Mediterranean Outflow Water, [START_REF] Van Rooij | The Le Danois Contourite Depositional System: interactions between the Mediterranean outflow water and the upper Cantabrian slope (North Iberian margin)[END_REF]. Moreover, Pliocene-Pleistocene evolution of the Aquitaine Platform records a two steps evolution, the emplacement of megafans with the most striking one i.e. Lannemezan megafan starting during Messinian up to Uppermost Pliocene [START_REF] Ortiz | Sediment routing system and sink preservation during the post-orogenic evolution of a retro-foreland basin: The case example of the North Pyrenean (Aquitaine, Bay of Biscay) Basins[END_REF]. This megafan mainly source by the Neste River is dissected during Late Quaternary (at or before 300 ka, [START_REF] Mouchené | Controls on Quaternary incision of the Northern Pyrenean foreland: Chronological and geomorphological constraints from the Lannemezan megafan, SW France[END_REF]. This indicates a shift from a sedimentation phase to an incision phase, that takes place between 2.6 Ma and 300 ka. This supports the hypothesis of recycling by erosion of previous deposits sediments in the Aquitaine Platform.

Although glaciations is well documented during Late Quaternary in the Pyrenees [START_REF] Calvet | Recent advances in research on Quaternary glaciations in the Pyrenees[END_REF][START_REF] Delmas | Exposure age chronology of the last glaciation in the eastern Pyrenees[END_REF], their importance in terms of sedimentary budget is still not quantified. Identified glacial remnants are restricted to the upper part of the valleys and mostly confined in the mountains belts [START_REF] Delmas | Palaeogeography and 10Be exposure-age chronology of Middle and Late Pleistocene glacier systems in the northern Pyrenees: implications for reconstructing regional palaeoclimates[END_REF]. The preservation over large areas of preglacial flat surfaces in the high chain (Bosch et al., 2016) claim for erosion localized mainly in glacial valleys. This supports the hypothesis of a more localized erosion in the mountain valleys.

Sediment budget evolution between onshore and offshore

The change of the sediment ratio between onshore and offshore (ROnOff) from 25.3 (66 to 33.9 Ma) to 0.01 (5.3 to 0 Ma) has to be related to the general evolution of the two basins as summarized in item 2.2. This drastic change of ratio in favour of the "ultimate sink" is in line with the synthesis of Hinderer, 2012.

 The first interval (66.0-33.9 Ma) spans a long period of time and several steps of the orogeny. A first phase (66-56 Ma) of relatively quiescent with very low relief in the mountain belt and siliciclastic input, a second phase (56-33.9 Ma) that correspond to progressive mountain building with increasing relief and erosion. At around 40 Ma, deformation propagate in the foredeep and segmented the foredeep. During this entire period, accommodation space created by the flexure was large enough to trap siliciclastic sediments coming from the incipient mountain belt. This may explain the general trend between 66 and 33.9 Ma.  The second period (33.9-23.03 Ma) also spans different periods, paroxysm of denudation in the Mountain belt, while in the Aquitaine Platform, two periods are deciphered, a first period of accumulation and deformation (up to 25.2 Ma) and a second with a decrease of subsidence and increase of export to the distal sink (since 25.2 Ma). As a consequence, since 25.2 Ma, siliciclastic supply is too important compare to the accommodation space creation and the sediments are transferred to the progradational wedges in the Aquitaine platform. This explains the trend during Oligocene and particularly since 25.2.

 During the post-orogenic period, first the Aquitaine platform subsidence drastically decreased (25.2-10.6 Ma) and second this domain was partly uplifted (10.6-0 Ma). This favored the sediment export to the deep-sea domain, first poorly balanced (ROnOff at 0.18 -map 23.03-5.3 Ma) and then unbalanced (ROnOff at 0.01 -map 5.3-0 Ma).

Conclusion

Our objective was to measure the siliciclastic sediment volumes and rates of a retroforeland basin and its lateral deep equivalent, during the end tectonic and topographic evolution of the Pyrenees mountain belt.

(1) The amount of sediments is of 51 500 ± 16 800 km 3 for the Cenozoic.

(2) The siliciclastic sediment rate curve during Cenozoic shows two major increase around 26.0 and 2.5 Ma. This last one is a major increase. This is in agreement with the worldscale trend of [START_REF] Hay | Mass-balanced paleogeographic reconstructions[END_REF], expected of climatic origin by [START_REF] Molnar | Late Cenozoic uplift of mountain ranges and global climate change: chicken or egg?[END_REF].

The 26.0 Ma increase is clearly related to the exhumation of the Pyrenees of tectonic origin. The discussion on the major 2.5 Ma episode is still open.

(3) The mass balance between the Aquitaine Platform and the deepest domains (Landes Plateau, Bay of Biscay) change through time in favour to the deep domain. This might be explained by the ratio between subsidence created accommodation space and the produced siliciclastic sediments by the mountain belt on the platform. This confirms and quantifies the stratigraphic model of sink preservation proposed by [START_REF] Ortiz | Sediment routing system and sink preservation during the post-orogenic evolution of a retro-foreland basin: The case example of the North Pyrenean (Aquitaine, Bay of Biscay) Basins[END_REF]. This also suggests the sediment accumulation in the deep part of the margin is only controlled by the accommodation/sedimentation balance on the platform. [START_REF] Cremer | Approches sédimentologique et géophysique des accumulations turbiditiques: l'éventail profond du Cap-Ferret (Golfe de Gascogne), la série des grès d'Annot (Alpes-de-Haute-Provence) 1 Thèse[END_REF]Iglesias, 2009). B: interpreted cross-section from the proximal Aquitaine Basin part to the deep Bay of Biscay Basin, the considered period (isopach map) is highlighted by colour in the crosssection.

Figure 4: A: Oligocene preserved sediment thickness (isopach, meters) map. The volume quantification western limit is according to the deep sea fan location [START_REF] Cremer | Approches sédimentologique et géophysique des accumulations turbiditiques: l'éventail profond du Cap-Ferret (Golfe de Gascogne), la série des grès d'Annot (Alpes-de-Haute-Provence) 1 Thèse[END_REF]Iglesias, 2009). B: interpreted cross-section from the proximal Aquitaine Basin part to the deep Bay of Biscay Basin, the considered period (isopach map) is highlighted by colour in the cross-section.

Figure 6: A: Pliocene-Pleistocene preserved sediment thickness (isopach, meters) map. The volume quantification western limit is according to the deep sea fan location [START_REF] Cremer | Approches sédimentologique et géophysique des accumulations turbiditiques: l'éventail profond du Cap-Ferret (Golfe de Gascogne), la série des grès d'Annot (Alpes-de-Haute-Provence) 1 Thèse[END_REF]Iglesias, 2009[START_REF] Brocheray | 2000 years of frequent turbidite activity in the Capbreton Canyon (Bay of Biscay)[END_REF]. B: interpreted cross-section from the proximal Aquitaine Basin part to the deep Bay of Biscay Basin, the considered period (isopach map) is highlighted by colour in the cross-section. [START_REF] Ortiz | Sediment routing system and sink preservation during the post-orogenic evolution of a retro-foreland basin: The case example of the North Pyrenean (Aquitaine, Bay of Biscay) Basins[END_REF], some parts of the interpretation are of higher resolution than the resolution of the calculations in this paper (i.e. Palaeocene-Eocene, Oligocene, Miocene, Pliocene-Pleistocene). For example, the figure 5 in [START_REF] Ortiz | Sediment routing system and sink preservation during the post-orogenic evolution of a retro-foreland basin: The case example of the North Pyrenean (Aquitaine, Bay of Biscay) Basins[END_REF] shows several high resolutions surfaces (thanks to orbitostratigraphy) at 32.2, 32.0, 31.3, 29.4, 27.1, 26.4, 25.2, 24.5, 24.4 Ma for the Oligocene period. This resolution on different parts of the cross section allows us to make a precise quantification shown in the figure. This figure is a compilation of the percentage of 2D area normalized to their duration thanks to high resolution timeline on different cross section published in [START_REF] Ortiz | Sediment routing system and sink preservation during the post-orogenic evolution of a retro-foreland basin: The case example of the North Pyrenean (Aquitaine, Bay of Biscay) Basins[END_REF]

  located at the transition between the southeastern part of the South Armorican shelf and the Landes High and (2) to the south, an E-W trending depocenter located north of the Capbreton canyon. The preserved sediments along the deep Bay of Biscay are organized as an E-W trending body more than 100 km-large located on the Biscay Wedge Front. It is upstream in connection with the two depocenters of the Landes Plateau.

  ) time-interval shows an accentuation of the sediment distribution pattern established during Miocene. (1) No to very few sediments were preserved on the Aquitaine Platform. (2) Two depocenters occurred on the Landes Plateau: (i) a N-S trending one north to the Landes High (progradationnal wedges -Ortiz et al., 2020) and (ii) a N-S trending one south of the Landes High. (3) The depocenters of the deep Bay of Biscay are located (i) at the base of slope of the South Armorican shelf and (ii) along the Biscay Wedge Front in connection with the northern depocenter of the Landes Plateau.

Figure 1 :

 1 Figure 1: A: Main physiographic and structural features and available dataset of seismic

Figure 2 :

 2 Figure 2: Synthetic chart of the main events (deformation, topography, sediment routing) of

Figure 7 :

 7 Figure 7: Siliciclastic sedimentation volumes and rates of the Aquitaine Basin and Bay of

Figure 8 :

 8 Figure 8: In the cross sections published in Ortiz et al., (2020), some parts of the interpretation

Acknowledgments

This work is part (and supported by) the 'Source-to-Sink compression' project that is jointly

Data Availability Statement

Research data are not shared