Liubomira Romanova
email: liubomiraromanova@gmail.com

Vincent Balter

Laurent Simon

Patrice Gérard

Nadejda Pokatilova

Eric Crubézy

Patrice Gerard

Eric Crubezy

Diet of autochthonous populations in Yakutia using isotopic, ethnographic, historical and archaeological data

Keywords: Carbon isotopes, nitrogen isotopes, Yakutia, Eastern Siberia, diet, 15th-19th centuries

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

Introduction

Today, archaeology uses a wide array of biological analyses to investigate the lifestyles of ancient populations. Stable isotope analyses are routinely applied for the reconstruction of past population dietary habits. Paleodietary studies using carbon and nitrogen stable isotope analyses have been conducted on populations of Siberia, in the Cis-Baikal region including the Upper Lena river [START_REF] Katzenberg | Stable isotope ecology and paleodiet in the Lake Baikal region of Siberia[END_REF][START_REF] Katzenberg | Paleodiet reconstruction of Bronze Age Siberians from the mortuary site of Khuzhir-Nuge XIV, Lake Baikal[END_REF][START_REF] Katzenberg | Prehistoric dietary adaptations among hunter-fisher-gatherers from the Little Sea of Lake Baikal, Siberia, Russian Federation[END_REF][START_REF] Weber | Hunter-gatherer foraging ranges, migrations, and travel in the middle Holocene Baikal region of Siberia: Insights from carbon and nitrogen stable isotope signatures[END_REF], Southern Siberia [START_REF] Murphy | Iron Age pastoral nomadism and agriculture in the Eastern Eurasian steppe: implications from dental palaeopathology and stable carbon and nitrogen isotopes[END_REF], Western Siberia [START_REF] Marchenko | Paleodiet, radiocarbon chronology, and the possibility of fresh-water reservoir effect for Preobrazhenka 6 burial ground, Western Siberia: preliminary results[END_REF], the Baraba forest steppe [START_REF] Privat | Economy and diet at the Late Bronze Age/Iron Age site of Chicha: artefactual, archaeozoological and biochemical analyses[END_REF][START_REF] Molodin | Fish in the burial rite of Andronovo (Fedorovka) people, based on Tartas-1 cemetery[END_REF], the Minusinsk Basin [START_REF] Svyatko | Stable isotope dietary analysis of prehistoric populations from the Minusinsk Basin, Southern Siberia, Russia: a new chronological framework for the introduction of millet to the Eastern Eurasian steppe[END_REF][START_REF] Svyatko | Dental palaeopathological analysis of the eneolithic-early iron age populations from the minusinsk basin, southern siberia: palaeodietary implications[END_REF], and the Altai Mountains (O' Connell et al., 2003). There is however a lack of studies focusing on East Siberia, where such analyses have a potentially large field of application, due to different ecological niches and a traditional way of life that has sometimes lasted until today.

Diet reconstruction with stable isotopes is implied in the sentence "We are what we eat". In other words, there is a direct relationship between the isotopic composition of the diet and consumer tissues. For carbon isotopes, a trophic level enrichment from diet to consumer is approximately 1‰, while for nitrogen isotopes it is 3 to 6‰ (De Niro and Epstein, 1981; [START_REF] Schoeninger | Nitrogen and carbon isotopic composition of bone collagen from marine and terrestrial animals[END_REF][START_REF] Bocherens | Trophic level isotopic enrichment of carbon and nitrogen in bone collagen: case studies from recent and ancient terrestrial ecosystems[END_REF][START_REF] Hedges | Nitrogen isotopes and the trophic level of humans in archaeology[END_REF] O' Connell et al., 2012). The carbon isotope value (δ13C) gives information about the distinction of diet based on C3 or C4 photosynthetic plant pathways as well as marine food resources. Freshwater sources however, have a significant variability in δ13C values [START_REF] Katzenberg | Stable isotope ecology and paleodiet in the Lake Baikal region of Siberia[END_REF]; [START_REF] Katzenberg | Prehistoric dietary adaptations among hunter-fisher-gatherers from the Little Sea of Lake Baikal, Siberia, Russian Federation[END_REF][START_REF] Katzenberg | Stable isotope analysis: a tool for studying past diet, demography and life history[END_REF]). In addition to δ13C values, nitrogen isotope values (δ15N) reveal information about the trophic position of an individual within a localised food resource. The advantage of the stable isotope method is the precise quantitative evaluation of the diet of humans and animals. It allows for the determination of the type of environment in which the subjects lived and their main food sources: plant, fish or terrestrial animal. It does not however allow us to distinguish different types of animal protein consumed by a subject, since meat and dairy products have the same isotopic value. Our research represents the first comprehensive study of the diet of the Yakut population which, to now, has been described through ethnographic studies only. The ancestors of the Yakuts (cow and horse breeders), populated the North East of Siberia, migrating from the South in the eleventh-thirteenth centuries AD [START_REF] Okladnikov | Istoriia Yakutskoi АSSR: Yakutiia do prisoedineniia k russkomu gosudarstvu. Izdatel'stvo Аkademii nauk SSSR[END_REF][START_REF] Alexeev | Drevniaia Iakutiia: zheleznyi vek i epokha Srednevekovʹia (Ancient Yakutia: The Iron Age and the Medieval Epoch)[END_REF][START_REF] Fedorova | Autosomal and uniparental portraits of the native populations of Sakha (Yakutia): implications for the peopling of Northeast Eurasia[END_REF]. People (Crubezy and Nikolaeva, 2017) and cattle [START_REF] Librado | Tracking the Origins of Yakutian Horses and the Genetic Basis for Their Fast Adaptation to Subarctic Environments[END_REF] adapted to extreme climatic conditions with winter temperatures that could reach -60°C. When Russian expansion began in Yakutia in the 1620s, Yakuts settled in the lands between the Lena, Amga and Aldan rivers (a location currently referred to as "Central Yakutia"), as well as at the mouth of Viluy river in the west, and along Yana river in the North-East [START_REF] Tokarev | Ocherk istorii yakutskogo naroda (Essay on the history of the Yakut people)[END_REF][START_REF] Okladnikov | Istoriia Yakutskoi АSSR: Yakutiia do prisoedineniia k russkomu gosudarstvu. Izdatel'stvo Аkademii nauk SSSR[END_REF][START_REF] Gogolev | Iakuty (problemy etnogeneza i formirovaniia kul'tury) (Yakuts (problems of ethnogenesis and culture formation))[END_REF]. Their lifestyle was considerably transformed by Russian colonisation.

After 1689, and the establishment of Yakut elites, inequalities increased (Crubezy and Nikolaeva, 2017). The number of bovines and horses owned by families determined their wealth. People without livestock were called "fishermen" suggesting that the poor had a diet based on fish. An important consumption of wild plants and larch bark has also been demonstrated in ethnographic studies [START_REF] Lindenau | Opisanie narodov Sibiri (pervaia polovina 18 veka) (Description of the peoples of Siberia (first half of the 18th century))[END_REF][START_REF] Middendorf | Puteshestvie na sever i vostok Sibiri: Sever i vostok Sibiri v estestvenno-istoricheskom otnoshenii. Korennye zhiteli Sibiri (Journey to the north and east of Siberia: North and east of Siberia in a natural-historical sense. Indigenous people of Siberia)[END_REF]Shiman'skii, 1885;[START_REF] Seroshevskii | Iakuty (The Yakuts). V.1. Spb[END_REF]. Agriculture, notably cereal crops, evolved from the 18th century.

Following Christianisation, which spread from the 1750s and became dominant in the majority of the population by 1855, led to the appearance of new dietary specificities. These were due to a notable increase in the prescription of religious fasts and other dietary restrictions throughout the year. Furthermore, ethnographic texts indicate that the Yakuts from Viluy had a more fish-based diet (Maak,1887;Ivanov, 2015). At the same time, burials reveal a number of animal bones and vessels with dairy products deposited as funerary meal (Crubezy and [START_REF] Crubézy | Chamane, kyys jeune fille des glaces[END_REF][START_REF] Crubézy | Mir drevnikh Iakutov: opyt mezhdisciplinarnykh issledovanii (The world of the ancient Yakuts : a transdisciplinary approach from the French/Yakut expedition)[END_REF]. Geographically, the closest isotopic studies were conducted in the Baikal region on Neolithic (5800-3000 BC) and Early Bronze (3400-1700 BC) Age [START_REF] Katzenberg | Stable isotope ecology and paleodiet in the Lake Baikal region of Siberia[END_REF][START_REF] Katzenberg | Paleodiet reconstruction of Bronze Age Siberians from the mortuary site of Khuzhir-Nuge XIV, Lake Baikal[END_REF][START_REF] Katzenberg | Prehistoric dietary adaptations among hunter-fisher-gatherers from the Little Sea of Lake Baikal, Siberia, Russian Federation[END_REF][START_REF] Weber | Hunter-gatherer foraging ranges, migrations, and travel in the middle Holocene Baikal region of Siberia: Insights from carbon and nitrogen stable isotope signatures[END_REF]. It has been noticed that humans from Upper Lena exhibited the lowest δ13C and δ15N values, indicating a diet based on local game and fish, when compared to the Baikal region and Angara valley where high values indicate mostly fish consumption [START_REF] Katzenberg | Stable isotope ecology and paleodiet in the Lake Baikal region of Siberia[END_REF][START_REF] Weber | Hunter-gatherer foraging ranges, migrations, and travel in the middle Holocene Baikal region of Siberia: Insights from carbon and nitrogen stable isotope signatures[END_REF]. In summary, these studies suggest that the diet of different archaeological cultures of Siberia was fluctuating through time and space due to their adaptation to the changing environment.

The main objective of this work is to better depict the diet of the Yakut population through by comparing an isotopic tool with ethnographic and archaeological studies. The study of ethnographic and historical texts enabled us to reveal several issues: (i) The relative importance of fish versus terrestrial resources in diet; (ii) The evolution of diet over time, especially under the Russian influence; (iii) The variation in diet depending on regions, and finally, (iv) The distinction in diet depending on economic status and sex. To test these hypotheses, we investigated the diet of ancient Yakuts using carbon (δ13C) and nitrogen (δ15N) isotope analysis in 61 subjects. In order to examine possible chronological and spatial differences, samples were selected from four regions of Yakutia dating from the 15th to the 19th century AD. Social and economic distinctions were determined by means of archaeological evidence.

Materials and methods

The French Archaeological Mission in Oriental Siberia (MAFSO) excavated more than 150 tombs dated from the 15th to the 19th century that were well preserved by permafrost. For this study, we sampled the femur from 61 individuals (37 men, 20 women and 4 children). These originated from three large regions of cattle breeders, that are otherwise ecologically and economically very different. Central Yakutia (n=36) is a large cattle breeding zone with numerous "alas" (thermokarstic lakes surrounded by pastures) (Crubezy and Alexeev, 2012). Viluy (n=10), is very humid and is known for its abundance of fish [START_REF] Maak | Viliuiskii okrug Iakutskoj volosti (Vilyuisk district of the Yakut). P.3, Tipografiia i khromolitografiia A. Transhelia[END_REF], and Verkhoyansk and Oymyakon (n=15) are regions of North Yakutia rich in wild game where hunting continues to provide a part of the diet of current populations (Figure 1).

Apart from geographic distribution and sex, we also divided the human remains into four major chronological eras (Crubezy and Alexeev 2007, 2012; Crubezy and Nikolaeva, 2017): before 1700 AD (n=12) when the Russian influence was not yet evident in the tombs; from 1700 to 1750 AD (n=35) during the Yakut Golden Age which witnessed a lineage taking power in Yakutia (Crubezy and Nikolaeva, 2017); from 1750 to 1800 AD (n=9) after the collapse of the Golden Age notably following smallpox [START_REF] Biagini | Variola Virus in a 300-Year-Old Siberian Mummy[END_REF] and tuberculosis epidemics [START_REF] Dabernat | Tuberculosis Epidemiology and Selection in an Autochthonous Siberian Population from the 16th-19th Century[END_REF]; and after 1800 AD (n=5) with a growing Russian influence on the economy and lifestyle (Burnasheva, 2015). We also identified four socio-economic groups according to the presence and type of artefacts in the graves: graves containing no artefacts (n=16), poor burials with one to five artefacts (n=14), middle class graves with six to ten artefacts (n=22), and a group of local elites with more than ten artefacts (n=9) (Table 1). We also collected animal samples from burial grounds and completed this list with modern samples (mostly fish) (Table 2).

Pieces of 1-2 cm of human femur bone were cleaned and abraded to remove surface contaminants and then crushed into particles smaller than 1 mm. Collagen was extracted according to Longin's protocol [START_REF] Longin | New method of collagen extraction for radiocarbon dating[END_REF]) with modifications by Brown [START_REF] Brown | Improved collagen extraction by modified Longin method[END_REF]. About 500 mg samples were put in a solution of equal 5ml volumes of methanol and chloroform and ultrasonically cleaned for 15 min to eliminate lipids and humic contaminants.

The samples were then rinsed with distilled water and demineralised with hydrochloric acid (5 ml of 1M HCl) for one hour in a rocking tube mixer. Once cleaned (i.e. the solution was not cloudy) the samples were put in hydrochloric acid at a low concentration (10 ml of 0.01 M HCl) and solubilised in an oven at 90°C for 17 hours. The liquid was then filtered and frozen for more than 1 hour. The samples were finally freeze-dried for 48 hours. Five mg samples of the collagen extract were weighed in tin capsules which were combusted in a Flash EA 1112 (Thermo Scientific) elemental analyser coupled in continuous flow to a Isoprime 100 (Elementar) isotope ratio mass spectrometer. Carbon and nitrogen isotope measurements were calibrated using in house standards of casein and aspartic acid, calibrated against international standards from the International Atomic Energy Agency, Vienna, Austria (IAEA-CH3, IAEA-CH6, IAEA-N1, IAEA-N2). The δ13C and δ15N values were expressed relative to VPDB and AIR respectively, and are expressed in ‰ of the deviation from the international standard using: δX = (Rsample/ Rstandard -1) × 1000, where X is 13C or 15N and R is the isotope ratio of the sample or the standard (i.e. 13C/ 12C or 15N/14N). Isotope analyses of "outliers" showing extremely low δ15N values have been repeated several times. The collagen extraction was carried out at the Ecole Nationale Supérieure (ENS), Lyon, Geology Laboratory and the carbon and nitrogen measurements were carried out at the "Isotope Ecology" platform of the Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (LEHNA) Laboratory, Lyon.

Results

Faunal samples

The δ13C recorded in the collagen of domestic and wild terrestrial mammals showed that they all occupied the same ecosystem and did not consume marine plants or C4 photosynthesis terrestrial plants. The δ13C value varied from -20.3 to -22.7‰, with a mean value of -21.6 ± 0.8 (1SD, n = 12). The highest isotopic values (δ13C = -20.3‰ and δ15N = 9.5‰) were observed in the dog which is the only omnivore (Figure 2). The δ15N value of terrestrial herbivores ranged from 1.6‰ to 8.0‰ with a mean value of 4.5 ± 1.7 (1SD, n = 11). The horse δ15N values ranged from 3.5 ‰ to 8.0‰ with a mean value of 4.9 ± 1.4 (1SD, n = 9). The samples of hare and bovine were lower, 3.4‰ and 1.6‰ respectively. The data on terrestrial animals are similar to previous studies on the region (Figure 3). The modern dog has similar values to the prehistoric dog from Upper Lena (δ13C = -19.1‰; δ15N = 9.7‰) (Weber, 2002); and exactly the same as a Neolithic wolf (δ13C = -20.2‰; δ15N = 9.7‰) from the Baikal region [START_REF] Losey | Canids as persons: Early Neolithic dog and wolf burials, Cis-Baikal, Siberia[END_REF] which indicates that its diet was based on terrestrial animals. Ordinarily, the dog is considered to feed on human leftovers. In this way its stable isotopes values can be used as indicator of a human diet from the same environment.

Isotopic values for fish were very heterogeneous (Figure 2). Carbon isotopic values varied from -27.2 to -24.3‰ with a mean value of -25.9 ± 1.3 (1SD, n = 4) for river fish (dace, pike) to lake fish (carp) which ranged from -16.1 to -11.5‰ with a mean value of -14.3 ± 2.5 (1SD, n = 3) except for the carp from the Nam region (Central Yakutia) with a δ13C of -29.8‰ and δ15N of 7.5‰ close to the value of pike from the same region (δ13C = -25.6‰, δ15N = 7.9‰). The δ15N of fish is higher than that of terrestrial herbivores [START_REF] Katzenberg | Stable isotope ecology and paleodiet in the Lake Baikal region of Siberia[END_REF][START_REF] O'connell | The importance of fish in the diet of central Eurasian peoples from the Mesolithic to the Early Iron Age[END_REF][START_REF] Shishlina | Paleoecology, subsistence, and 14C. chronology of the Eurasian Caspian steppe Bronze Age[END_REF] and varies between 7.5 and 11.6‰. Carp have δ15N values between 7.5 and 11.6‰ with a mean value of 9.6 ± 1.7 (1SD, n = 4). River fish have δ15N values between 7.9 and 9.1‰ with a mean value of 8.2 ± 0.6 (1SD, n=4). The δ15N values of archaeological fish remains from Central Yakutia (site Jarama) is significantly higher (11.6‰) than modern fish samples with an average δ15N value of 8.5 ± 0.9 (1SD, n = 7).

Carbon stable isotopes values for carp are broadly in accordance with values of Baikal lake fish, and those of dace and pike match with Angara and Lena river fish values (Figure 3). In general, they show a wide range of δ13C values which is explained by the fact that pelagic (open water) and benthic (deep water) fish have lower δ13C values (about -24.6‰) than species from littoral zones (-12.9‰) (Katzenberg and Weber, 1999; [START_REF] Katzenberg | Prehistoric dietary adaptations among hunter-fisher-gatherers from the Little Sea of Lake Baikal, Siberia, Russian Federation[END_REF]. Finally, δ15N values of fish from Yakutia are lower than those presented in former studies. This can be explained by low primary productivity in Yakutia water systems [START_REF] Weber | Hunter-gatherer foraging ranges, migrations, and travel in the middle Holocene Baikal region of Siberia: Insights from carbon and nitrogen stable isotope signatures[END_REF].

Human samples

The δ13C values for all human bones ranged between -22.0 to -18.7‰ (Figure 2 (Figure 2). The δ15N value of individuals consuming mainly the meat and dairy products of terrestrial animals is estimated to be in the range of 7.5 to 9.5‰ (n = 4), while values higher than 11.2‰ can indicate a diet rich in fish (n = 23). We presume that δ15N values between 9.5 and 11.2‰ indicate a mixed diet in which fish and meat have the same importance (n = 31). Three samples noted above with significantly low δ15N values: 4.4‰, 4.9‰, and 5.3‰, two from Central Yakutia and one from Viluy, respectively (all masculine) dating from the 18th century are considered as outliers and we did not include them in comparison studies presented below.

Dietary differences between phases and regions

The variability of δ13C values is higher in Central Yakutia with a range of 2.9‰ and Viluy (where the range is 2.6‰) than in North (where the range is 1‰). This suggests that varying proportions of plant and animal food may exist in the diet typical of Central Yakutia and the Viluy river, while a more uniform diet may have been practiced in the Northern regions. The variability of δ13C values is also higher before 1700 AD (δ13C = -20.1‰ ± 0.74, 1SD, n = 12) than during 1700-1750 AD (δ13C = -20.5‰ ± 0.50, 1SD, n = 28), during 1750-1800 AD (δ13C = -20.4‰ ± 0.56, 1SD, n = 16), and after 1800 AD (δ13C = -20.6‰ ± 0.25, 1SD, n = 5). Values of δ15N are the highest in the Viluy region with a mean δ15N value of 11.7‰ ± 0.9 (1SD, n = 9). Samples from Central Yakutia show the largest range of δ15N values which vary from 9.5 to 11.9‰ (δ15N = 11.0‰ ± 0.7, 1SD, n = 34). These values indicate an important role of fish in the diet of individuals from these two regions. Lower δ15N values are found in the North (Indiguirka and Verkhoyansk) with a mean δ15N value of 10.0‰ ± 0.5 (1SD, n = 15), which indicates a diet based on meat and dairy products of terrestrial herbivores in addition to plants (Figure 2).

The comparison of the C and N stable isotope evidence for ancient Yakut with Neolithic and

Early Bronze Age humans of the Cis-Baikal area shows both regional and temporal variations in diet and subsistence (Figure 3). The Yakut horse-breeder δ13C and δ15N values (δ13C= -20.4±0.5, δ15N=10.8±0.9 (1SD, n=58) indicate a meat and fish-based diet due to the light isotopic values of fish in this geographical area. They appear lighter compared to foragers of the Baikal region. The difference is significant when it comes to the Little Sea (δ13C= -

Dietary differences between male and female and between socio-economic groups

When comparing the diet of males and females, we did not distinguish individuals by regions and periods but included all samples from 1700 to post 1800 where both women (n=21) and men (n=25) were represented. The average of both δ15N and δ13C values were found to be exactly the same for male (δ13C = -20.4‰ ± 0.4 and δ15N = 10.8‰ ± 0.8, 1SD, n = 25) and female (δ13C = -20.4‰ ± 0.3 and δ15N = 10.8‰ ± 0.8, 1SD, n = 21) samples, highlighting similar dietary habits among genders. Pairwise comparisons of socio-economic groups do not show isotopic variations depending on social status. However, the variability of both δ15N and δ13C values of local elite group's individuals is lower than for other social groups ("elites": δ13C = -20.4‰ ± 0.1 and δ15N = 11.2‰ ± 0.5, 1SD, n = 9, "middle group": δ13C = -20.5‰ ± 0.3 and δ15N = 10.5‰ ± 0.8, 1SD, n = 20; "poor": δ13C = -20.1‰ ± 0.5 and δ15N = 11.3‰ ± 1.1, 1SD, n = 13, and tombs without material: δ13C = -20.4‰ ± 0.6 and δ15N = 10.7‰ ± 0.7, 1SD, n = 16). This suggests that they had a more stable diet than other social groups.

Discussion

The differences between species of herbivore animals depend on variations in the isotopic composition of the plants consumed, digestive processes and ecological factors. Generally, the isotopic data of herbivores are higher in arid than in humid zones [START_REF] Ambrose | Effects of diet, climate and physiology on nitrogen isotope abundances in terrestrial foodwebs[END_REF][START_REF] Bocherens | Isotopes stables et reconstitution du régime alimentaire des hominidés fossiles: une revue[END_REF]. This is the case in Yakutia. The high δ15N values in horse samples are characteristic for young animals and can be explained by the fact that they are suckled until being slaughtered [START_REF] Bocherens | Isotopes stables et reconstitution du régime alimentaire des hominidés fossiles: une revue[END_REF]. Yakuts are unique horse breeders who commonly slaughter young animals at the age of eight or nine months for climatic and economic reasons, (born in March, foals grow up and gain weight until November, a month with sufficiently stable cold temperatures to keep meat outside). The difference in isotopic values between the herbivores and the dog (δ15N=5.0‰ and δ13C=1.4‰) shows an enrichment in animal protein content with one trophic level leading the dog values to be comparable to human values, suggesting a diet based mostly on terrestrial animals. Regarding aquatic resources, we propose that the important variability of δ13C and δ15N values of fish samples is due to differences in trophic sources and vegetation in lakes and rivers in Yakutia. However, the C and N isotopic signatures of fish analysed in the present study show good similarities with those of the Baikal Lake and adjacent regions (Figure 3).

The distribution of δ13C and δ15N values illustrates the variety of dietary behaviours of Yakuts.

We observed the existence of different trophic/dietary zones: that of consumers of terrestrial herbivores in the North, a group in Viluy with a diet rich in fish; and a group with a diverse diet in Central Yakutia. These results are in accordance with ethnological literature [START_REF] Maak | Viliuiskii okrug Iakutskoj volosti (Vilyuisk district of the Yakut). P.3, Tipografiia i khromolitografiia A. Transhelia[END_REF][START_REF] Hudiakov | Kratkoe opisanie Verhoianskogo okruga (Brief description of the district of Verkhoyansk)[END_REF]) that shows a more varied diet in Central Yakutia than in the two other regions.

We did not identify a clear difference between men and women, however a difference between social groups is evident with a regular consumption of meat and milk for subjects associated with rich tombs compared to those associated with modest tombs. This also confirms ethnological data [START_REF] Seroshevskii | Iakuty (The Yakuts). V.1. Spb[END_REF][START_REF] Maak | Viliuiskii okrug Iakutskoj volosti (Vilyuisk district of the Yakut). P.3, Tipografiia i khromolitografiia A. Transhelia[END_REF]. High δ15N values in the earlier phase can be due to a significant consumption of fish and herbivore protein, mainly, foal meat, before the 17th century, which slowly decreased during the 18th century.

Archaeological data attests to horse breeding and consumption, and to a lesser extent, cattle breeding and hunting, while there is occasional evidence for fishing and fish consumption.

Among 61 analysed tombs, 16 did not have any archaeological artefacts, while 45 included some indications of diet such as vessels and/or meat and dairy products (Figure 4). The tombs did not contain any fish remains, probably for the reason that fish was not considered to be honorific as being a part funeral meal. The crucian carp bones investigated for this work come from the Jarama site where a few fish bones were discovered outside of the coffins of three child tombs. Funeral meals in analysed human tombs consists mostly of meat remains (38/45), and sometimes were associated with dairy products (12 cases). Milk product is rarely deposited by itself (3/45), nevertheless numerous vessels present in almost all tombs with artefacts (43/45) could initially have contained milk. Comparing our results tomb by tomb with archaeological data, we noted certain points: the Taralay subject, prior to 1700 AD, has one the highest δ15N value (12.7‰) which indicates a fish-based diet. This was the only tomb in which we found a fishing tool among funerary artefacts (a larch pick-axe used to break the ice for fishing during winter) (Figure 5). Three subjects had an extremely low δ15N value, comparable to that of terrestrial herbivores. This defines that, at least during the last 8 years of their life (a timespan considered to affect the isotopic value), they had a dominantly vegetarian diet. In the tombs of these three subjects, however, the remains of funerary meals contained dairy and horse meat. Among these three subjects, two older men had lost almost all their teeth before death, which might indicate a soft vegetarian diet rather than a meat-based diet. Physiological effects such as starvation, and inversely overconsumption may also influence δ15N values [START_REF] Hedges | Nitrogen isotopes and the trophic level of humans in archaeology[END_REF]Balter et al., 2006). Multiple ethnographical and historical sources attest to the importance of plants and larch bark's flour in the diet of the Yakuts, in particular for poor people. There may have been a possibility of mis-identification of samples. New sampling of the specified burials will therefore have to be conducted.

Conclusions

The diet of Yakut population from 15th to 19th centuries appears relatively homogeneous according to ethnographic data. However, δ13C and δ15N values demonstrate a clear distinction between different geographical areas of Yakutia. We also documented variations in dietary habits related to social status. Men and women had the same type of diet. These results are correlated with ethnographical and historical evidences. We noticed considerable variation in δ15N values for terrestrial animals while δ13C turned out to be a less significant variable.

We found that the N isotope composition of suckling horses was notably elevated. We also confirmed the existence of wide variation in δ13C and δ15N among fish from rivers and lakes. This indicates that the high δ15N values measured in humans could be explained not solely by an intake of freshwater fish, but also by the consumption of young animals, especially foals. In this context, it would be interesting to analyse the isotopes of sulphur and strontium/calcium and barium/calcium ratios [START_REF] Balter | Were Neandertalians essentially carnivores? Sr and Ba preliminary results of the mammalian palaeobiocoenosis of Saint-Césaire[END_REF]Balter and Simon, 2006) to distinguish the consumption of freshwater fish and terrestrial animals [START_REF] Privat | The distinction between freshwater-and terrestrial-based diets: methodological concerns and archaeological applications of sulphur stable isotope analysis[END_REF]. Carbon and nitrogen isotopic results for human samples. Isotope values are expressed in per mil. The social status is determined by number of artefacts: ○ -no material • -poor (1 to 5 artefacts). •• -middle (6 to 10 artefacts). ••• -rich (more than 10 artefacts).

Captions for figures and tables

•• -rich (more than 10 artefacts).

  ). The average was -20.4‰ ± 0.6 (1SD, n = 61) and is slightly higher than values of herbivores. It is equal to a one step change in trophic level, the average δ13C value for herbivores being -21.7‰ ± 0.7 (1SD, n = 11). Occasional consumption of freshwater resources occurs. This is shown by the high δ15N values (>9.5‰) of some individuals together with their low δ13C values, indicative of consumption of freshwater fish. The lowest human δ13C values are observed in three exceptional cases with extremely low δ15N values (Ordiogone 2: δ13C = -21.1, δ15N = 5.3‰; At Daban 7: δ13C = -21.9, δ15N = 4.4‰; Sytygane Sihe2: δ13C = -22.0, δ15N = 4.9‰). Their low δ15N value is similar to those found for the herbivore specimens analysed and attests to the importance of plants in their diet to the detriment of animal proteins. Nevertheless, we do not completely exclude the possibility of wrong identification of faunal samples as human. One old man from the Viluy region (Tungus Keul 5: δ13C = -21.3‰; δ15N =11.6‰) also has one of the lowest δ13C values but, considering its high δ15N value, this suggests a mainly fishbased diet in this case. The δ15N values for all human bones ranged between 4.4‰ to 12.9‰

18.2±3. 8 ,

 8 δ15N=14.0±1.6 (1SD, n=101), South-western Baikal (δ13C= -16.3±0.7, δ15N=14.6±1.0 (1SD, n=62) or Angara valley (δ13C= -16.7±1.4, δ15N=13.2±1.4 (1SD, n=119) where fish and sometimes seal meat from the Baikal seem important in the diet of hunters-gatherers. In the meantime, these values are close to the foragers of Upper Lena (δ13C= -19.8±0.5, δ15N=11.0±1.1 (1SD, n=28) characterised by consumption of local fish and meat.

Figure 1 .

 1 Figure 1. Localisation of the studied areas

Figure 2 .

 2 Figure 2. Carbon and nitrogen isotopic results of the study. The close-up is given for humans.

Figure 3 .

 3 Figure 3. Carbon and nitrogen isotopic results of the present study in the context of available isotopic data of the Baikal Lake and adjacent areas. Data are from Katzenberg and Weber, 1999; Katzenberg et al., 2009; Katzenberg et al., 2012; Weber et al., 2011.

Figure 4 .Figure 5 .

 45 Figure 4. The ribs of the horse and the ritual cup tchoron with the dairy product in the tomb Kerdugen, 1700-1750 AD Figure 5. Fishing tool in the tomb Taralay, Central Yakutia, before 1700 Table 1. Carbon and nitrogen isotopic results for human samples. Isotope values are expressed in per mil. The social status is determined by number of artefacts: ○ -no material • -poor (1 to 5 artefacts). •• -middle (6 to 10 artefacts). ••• -rich (more than 10 artefacts).

Table 2 .

 2 Carbon and nitrogen isotopic results for animal samples. Isotope values are expressed in per mil

						Elemental	Elemental
	Species	Site	Region	δ 13 C	δ 15 N	composition	composition	C/N
						%C	%N
	Archaeological
	Horse (Equus ferus caballus)	Ordiogone 2	Viluy	-21.4	4.9	42.3	15.1	2.8
	Horse (Equus ferus caballus)	Ordiogone 1	Viluy	-22.0	3.5	40.1	15.0	2.7
	Horse (Equus ferus caballus)	Tungus keul 4	Viluy	-22.1	4.5	42.6	15.5	2.7
	Horse (Equus ferus caballus)	Oyogosse tumula	Viluy	-21.1	8.0	41.2	15.1	2.7
	Horse (Equus ferus caballus)	Ordiogone 1	Viluy	-21.7	4.2	42.6	15.7	2.7
	Horse (Equus ferus caballus)	Celyysse	Viluy	-22.4	4.0	42.5	15.5	2.7
	Horse (Equus ferus caballus)	Okhtoubout 2	Central Yakutia	-20.6	6.4	39.3	14.4	2.7
	Horse (Equus ferus caballus)	Bakhtakh 2	Verkhoyansk	-22.2	4.9	42.6	15.6	2.7
	Bovine (Bos taurus)	Isting tumula	Viluy	-20.8	1.6	42.8	15.5	2.8
	Hare (Lepus timidus)	Dakky kuola	Viluy	-22.7	3.4	39.6	14.5	2.7
	Carp (Carassius carassius)	Jarama	Central Yakutia	-16.1	11.6	39.5	15.4	2.6
	Modern
	Dog (Canis familiaris)	Ordiogone	Viluy	-20.3	9.5	38.1	14.0	2.7
	Carp (Carassius carassius)	Nam	Central Yakutia	-29.8	7.5	38.3	14.1	2.7
	Carp (Carassius carassius)	Kobiaï	Central Yakutia	-15.4	9.8	38.9	14.9	2.6
	Carp (Carassius carassius)	Amga	Central Yakutia	-11.5	9.3	42.8	14.7	2.9
	Dace (Leuciscus leuciscus)	Pokrovsk	Central Yakutia	-27.2	8.0	44.4	14.7	3.0
	Dace (Leuciscus leuciscus)	Pokrovsk	Central Yakutia	-26.6	7.9	44.4	14.8	3.0
	Dace (Leuciscus leuciscus)	Pokrovsk	Central Yakutia	-24.3	9.1	37.3	13.9	2.7
	Pike (Esox lucius)	Nam	Central Yakutia	-25.6	7.9	42.9	14.1	3.0

Acknowledgments

This research is supported by the French Archaeological Mission in Oriental Siberia (Ministry of Foreign and European Affairs, France), French Embassy in Russia, North-Eastern Federal University (Yakutsk, Sakha Republic), and the Human Adaptation program of the French Polar Institute Paul Émile Victor. We thank the anonymous reviewers for their insightful comments and suggestions. Special thanks to Dr. Richard Fosse for his careful reading of our manuscript.

Bibliography


James M D Day
email: jmdday@ucsd.edu

Paolo A Sossi

Charles K Shearer

Frederic Moynier

The Rusty Rock 1

Keywords: Copper isotopes, iron isotopes, Moon, Rusty Rock, condensates, volatile elements, evaporation

The Apollo 16 'Rusty Rock' impact melt breccia 66095 is a volatile-rich sample, with the volatiles inherited through vapor condensation from an internal lunar source formed during thermo-magmatic evolution of the Moon. We report Cu and Fe isotope data for 66095 and find that bulk-rocks, residues and acid leaches span a relatively limited range of compositions (3.0 ±1.3 wt.% FeO [range = 2.0-4.8 wt.%], 5.4 ±3.1 ppm Cu [range = 3-12 ppm], average δ 56 Fe of 0.15 ± 0.05‰ [weighted mean = 0.16‰] and δ 65 Cu of 0.72 ± 0.14‰ [weighted mean = 0.78‰]). In contrast to the extreme enrichment of light isotopes of Zn and heavy isotopes of Cl in 66095, δ 65 Cu and δ 56 Fe in the sample lie within the previously reported range for lunar mare basalts (0.92 ± 0.16‰ and 0.12 ± 0.02‰, respectively). The lack of extreme isotopic fractionation for Cu and Fe isotopes reflects compositions inherent to 66095, with condensation of a cooling gas from impactgenerated fumarolic activity at temperatures too low to lead to the condensation of Cu and Fe, but higher than required to condense Zn. Together with thermodynamic models, these constraints suggest that the gas condensed within 66095 between 700 and 900 °C (assuming a pressure of 10 -6 and an fO2 of IW-2). That the Cu and Fe isotopic compositions of sample 66095 are within the range of mare basalts removes the need for an exotic, volatile-enriched source. The enrichment in Tl, Br, Cd, Sn, Zn, Pb, Rb, Cs, Ga, B, Cl, Li relative to Bi, Se, Te, Ge, Cu, Ag, Sb, Mn, P, Cr and Fe in the 'Rusty Rock' is consistent with volcanic outgassing models and indicates that 66095 likely formed distal from the original source of the gas. The volatile-rich character of 66095 is consistent with impact-generated fumarolic activity in the region of the Cayley Plains, demonstrating that volatile-rich rocks can occur on the lunar surface from outgassing of a volatile-poor lunar interior. The 'Rusty Rock' indicates that the lunar interior is significantly depleted in volatile elements and compounds and that volatile-rich lunar surface rocks likely formed through vapor condensation. Remote sensing studies have detected volatiles on the lunar surface, attributing them dominantly to solar wind. Based on the 'Rusty Rock', some of these surface volatiles may also originate from the Moon's interior.

Introduction

Knowledge of the origin and distribution of volatile elements in and on the Moon is important for models of Earth-Moon system formation and planetary accretion and differentiation, as well as for understanding volcanism and surface volatile distributions (e.g., [START_REF] Taylor | Water, Water, Everywhere: But How to Find and Use It on the Moon! Annual Meeting of the Lunar Exploration Analysis Group 1685[END_REF][START_REF] Day | Evaporative fractionation of volatile stable isotopes and their bearing on the origin of the Moon[END_REF]. Initial work on Apollo samples found that the Moon is depleted with respect to the bulk silicate Earth for elements that are cosmochemically volatile or moderately volatile (e.g., [START_REF] Wolf | Moon and Earth: compositional differences inferred from siderophiles, volatiles, and alkalis in basalts[END_REF][START_REF] Jones | Geochemical constraints on the origin of the Earth and Moon[END_REF]. In this respect, volatile or moderately volatile elements can be defined by the 50% condensation temperatures at gas pressures of <10 -4 bar of 665 K and 1135 K, respectively [START_REF] Lodders | Solar system abundances and condensation temperatures of the elements[END_REF]. Early measurements of low initial Rb/Sr and high U/Pb ratios for lunar rocks implied an interior devoid of volatile and moderately volatile elements since its inception [START_REF] Papanastassiou | Rb-Sr ages of lunar rocks from the Sea of Tranquillity[END_REF][START_REF] Tatsumoto | Age of the moon: An isotopic study of uraniumthorium-lead systematics of lunar samples[END_REF].

Stable isotope signatures of Zn [START_REF] Paniello | Zinc isotopic evidence for the origin of the Moon[END_REF][START_REF] Kato | Extensive volatile loss during formation and differentiation of the Moon[END_REF], K [START_REF] Wang | Potassium isotopic evidence for a high-energy giant impact origin of the Moon[END_REF], Cl [START_REF] Sharp | The chlorine isotope composition of the Moon and implications for an anhydrous mantle[END_REF]Boyce et al. 2016), Cr [START_REF] Sossi | Volatile loss following cooling and accretion of the Moon revealed by chromium isotopes[END_REF]), Ga (Kato & Moynier, 2017) and Rb [START_REF] Pringle | Rubidium isotopic composition of the Earth, meteorites, and the Moon: Evidence for the origin of volatile loss during planetary accretion[END_REF] indicate that evaporation/condensation processes during or following lunar formation control the depletion in these elements. Regardless of when volatile depletion occurred, extreme depletions of volatile elements in lunar rocks, compared with primitive meteorites and Earth, indicate a highly energetic formation process and catastrophic outgassing of the material that formed the Moon [START_REF] Day | Evaporative fractionation of volatile stable isotopes and their bearing on the origin of the Moon[END_REF][START_REF] Albarède | An intrinsic volatility scale relevant to the Earth and Moon and the status of water in the Moon[END_REF].

In contrast to evidence for a volatile-depleted Moon, studies of some Apollo lunar crustal rocks have shown modest enrichment in moderately volatile elements (e.g., [START_REF] Krahenbuhl | Volatile elements in Apollo 16 samples: Implications for highland volcanism and accretion history of the moon[END_REF]. Lunar pyroclastic glass beads have Pb compositions revealing a source with 238 U/ 204 Pb (~25) only four times more depleted than Earth's mantle ( 238 U/ 204 Pb = ~6-8; [START_REF] Tatsumoto | Origin of lead from green glass of Apollo 15426: A search for primitive lunar lead[END_REF], while elevated abundances of OH, F, Cl and S in olivine melt inclusions from pyroclastic glass beads and mare basalts indicate that they are volatile-enriched [START_REF] Hauri | High Pre-Eruptive Water Contents Preserved in Lunar Melt Inclusions[END_REF]Chen et al., 2014). Water appears to be more depleted in the Moon than in Earth, however. For example, there is no petrographic evidence for water-rich mineral phases such as amphibole in mare basalts, which may relate to their lack of stability (e.g., [START_REF] Sisson | Experimental investigations of the role of H2O in calcalkaline differentiation and subduction zone magmatism[END_REF] due to low contents of moderately volatile Na and K in mesostasis and bulk lunar igneous rocks. Isotopically light Zn, Cu and Fe compositions also characterize the pyroclastic glasses [START_REF] Moynier | Isotopic composition of zinc, copper, and iron in lunar samples[END_REF][START_REF] Herzog | Isotopic and elemental abundances of copper and zinc in lunar samples, Zagami, Pele's hairs, and a terrestrial basalt[END_REF][START_REF] Kato | Extensive volatile loss during formation and differentiation of the Moon[END_REF], as well as light Zn in some mare basalts and crustal rocks [START_REF] Paniello | Zinc isotopic evidence for the origin of the Moon[END_REF][START_REF] Kato | Extensive volatile loss during formation and differentiation of the Moon[END_REF][START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF], indicating volatilerich vapor condensation. These signatures are inconsistent with complete evaporative loss of volatile elements from the Moon, requiring that some volatile components exist in its interior.

It is now established that volatile deposits occur on the lunar surface. Data from remote sensing missions have identified H-bearing species not only within permanentlyshadowed cold traps at polar regions, but also in non-polar regions of the Moon (e.g. [START_REF] Feldman | Fluxes of fast and epithermal neutrons from Lunar Prospector: Evidence for water ice at the lunar poles[END_REF][START_REF] Pieters | Character and spatial distribution of OH/H2O on the surface of the Moon seen by M3 on Chandrayaan-1[END_REF][START_REF] Paige | Diviner lunar radiometer observations of cold traps in the Moon's south polar region[END_REF][START_REF] Colaprete | Detection of water in the LCROSS ejecta plume[END_REF][START_REF] Li | Water on the surface of the Moon as seen by the Moon Mineralogy Mapper: Distribution, abundance, and origins[END_REF]. While much of this volatile-rich material has been attributed to solar wind implantation, some fraction of the volatile inventory may originate from lunar interior sources, even if the interior source was initially volatile-depleted [START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF].

To examine the distribution of volatile elements in and on the Moon, we present new Cu and Fe isotope data for the 'rusty rock', 66095. Sample 66095 is notable for several reasons. First, it is a type-example of a volatile-enriched lunar sample, with elevated contents of Bi, Br, Cd, Cl, Ge, I, Pb, Sb, Tl and Zn compared to other lunar samples [START_REF] Krahenbuhl | Volatile elements in Apollo 16 samples: Implications for highland volcanism and accretion history of the moon[END_REF][START_REF] Wanke | Multielement Analysis of Samples from Highland Breccia 66095: A contribution to the "Rusty Rock[END_REF][START_REF] Jovanovic | Aspects of the history of 66095 based on trace elements in clasts and whole rock[END_REF][START_REF] Ebihara | Trace elements in 59 mostly highland moon rocks[END_REF][START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF]. It is a fine to medium-grained impact melt breccia with elevated highly siderophile element abundances (0.001-0.1 × CI Chondrite; [START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF] that contains clasts of anorthosite, troctolite and basalt and an incompatibleelement rich ['KREEPy'] geochemical signature. Fragments of the impact melt breccia define an 87 Rb-87 Sr formation age of 4.06 ±0.24 Ga that is identical, within uncertainty, of the 207 Pb-206 Pb age of 4.01 ±0.06 Ga [START_REF] Nunes | Excess lead in "Rusty Rock" 66095 and implications for an early lunar differentiation[END_REF]. Initial 87 Sr/ 86 Sr for 66095 is 0.69909 ±5, consistent with a source with low long-term time-integrated Rb/Sr [START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF], while 85% of Pb in 66095 is unsupported by radioactive decay of U and Th, requiring a high 238 U/ 204 Pb (>570) source [START_REF] Nunes | Excess lead in "Rusty Rock" 66095 and implications for an early lunar differentiation[END_REF]. Second, the 'rusty' character of 66095 is due to the presence of akaganéite (FeOOH;Taylor et al., 1973) and lawrencite (FeCl2;[START_REF] Shearer | Chlorine distribution and its isotopic composition in "rusty rock" 66095. Implications for volatile element enrichments of "rusty rock" and lunar soils, origin of "rusty" alteration, and volatile element behavior on the Moon[END_REF]. The presence of these minerals has led to the hypothesis that volatile element enrichment occurred in 66095 either through alteration during transit to Earth [START_REF] Taylor | Rust" in the Apollo 16 rocks[END_REF], or through fumarolic activity on the Moon [START_REF] Krahenbuhl | Volatile elements in Apollo 16 samples: Implications for highland volcanism and accretion history of the moon[END_REF]Nunes & Matsumoto, 1973;[START_REF] Shearer | Chlorine distribution and its isotopic composition in "rusty rock" 66095. Implications for volatile element enrichments of "rusty rock" and lunar soils, origin of "rusty" alteration, and volatile element behavior on the Moon[END_REF]. During fumarolic activity, temperatures and Cl-rich gas compositions inferred for this process are potentially sufficient to mobilize the moderately volatile elements in the vapor phase.

Both Fe and Cu tend to form chloro-complexes at low temperatures (<700 °C), whereas the monatomic gas species are stable at magmatic temperatures [START_REF] Renggli | Volcanic gas composition, metal dispersion and deposition during explosive volcanic eruptions on the Moon[END_REF]. The stable isotopic fractionation between these different species and the condensed phase can therefore be used to query the nature of vapor deposition observed in 66095. In this study, we examine the isotopic and elemental fractionation of Cu and Fe with respect to other volatile and moderately volatile elements, and the implications for volatiles both in and on the Moon.

Sample, leaching/etching and digestion procedures

Three fragments of the 'Rusty Rock ', 66095, 421 (163 mg), 66095, 425 (173 mg) and 66095, 430 (201 mg) were used to measure Fe and Cu isotope compositions, with Zn isotope data presented for the samples previously by [START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF]. Samples 66095, 421 and 66095, 430 were dominantly grey crystalline material with no visible clasts, similar to fragments of poikilitic impact melt described previously [START_REF] Garrison | Genesis of highland basalt breccias: a view from 66095[END_REF][START_REF] Hunter | Rusty rock 66095: a paradigm for volatile-element mobility in highland rocks[END_REF]. Sample 66095, 425 was composed of pale-colored anorthosite-rich material, with black vitrophyric impact-melt glass. This clast is like the 'cataclastic anorthosite' clasts noted by [START_REF] Garrison | Genesis of highland basalt breccias: a view from 66095[END_REF].

A goal in studying 66095 was to assess isotopic heterogeneity within fragments of the sample, and a procedure of crushing and leaching/etching was designed and performed on samples (Table S1 of [START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF]. These protocols were developed based on previous leaching experiments and observations of volatile element heterogeneity observed in fragments of 66095 [START_REF] Jovanovic | Aspects of the history of 66095 based on trace elements in clasts and whole rock[END_REF]. In the first stage, sample 66095, 421 was powdered as a whole-rock sample, with no leaching or modification. Samples 66095, 425 and 66095, 430 were broken into two fragments. One fragment of each of these samples was powdered and digested, with no leaching or modification. These samples make up the 'bulk' measurements given in Table 1. The remaining materials, including powder from 66095, 421 and ground fragments from 66095, 425 and 66095, 430 were leached and the leachates (labelled as L) and residual fragments (labelled as R) were dried and precisely weighed to calculate concentrations.

Drying was performed between each leaching or etching step and was done in a class-10 hood at 100˚C. Weighing was done at room temperature (21.5˚C) in Teflon vessels using a Mettler Toledo XPE205 Analytical Balance with repeatability of 0.007 mg.

Three different leaching/etching experimental processes were used. For aliquots of 66095, 425(B) and 66095, 430 the sample powder was leached for 30 minutes in 18.2 MΩ H2O and the leachate was then separated from the residue (Exp. 1). For aliquots of 66095, 421 and 66095, 430, the sample powder was leached for 30 minutes in 1M HCl and the leachate separated from the residue (Exp. 2). Finally, a three-step leaching process was employed on 66095, 421 (Exp. 3). The first step was a 20-minute leach in 18.2 MΩ H2O, with ultra-sonification at 30°C. The H2O leachate was extracted, and 3M HCl was then added to the residue after dry-down and weighing. This second step was also for 20 minutes, with ultra-sonification at 30°C. When the 3M HCl was extracted from the residue, a strong odor of H2S was noticeable from all samples. The final etching stage involved addition of 1M HF-HNO3 after drying of the residue and weighing.

Reaction for this final stage took place for 2 hours on a hotplate at 60°C. After extraction of this final leaching stage, samples were dried down, and weighed prior to treatment in an identical fashion for dissolution, as described below. A total of 15 leachates/etchates, residues and whole-rock powders were measured for Fe isotope compositions and abundances, and 10 were analyzed for Cu isotope compositions due to limited available Cu in some of the water leachates.

After leaching/etching, all samples were dissolved in a 4:1 mixture of ultra-pure HF/HNO3 in Teflon beakers for 96 hours, dried down and then dissolved and further dried-down in 6M HCl twice to remove fluorides. Remaining solutions, after Zn column chemistry, were used to obtain Cu and Fe isotopic compositions.

Analytical protocols for Cu and Fe isotope analysis

All samples and external standards were purified for Cu isotope analysis using a single column ion chromatographic technique (modified after [START_REF] Maréchal | Precise analysis of copper and zinc isotopic compositions by plasma-source mass spectrometry[END_REF]used in Sossi et al., 2015). The procedure utilizes Bio-Rad AG1-X8 anion exchange resin, which, at low pH in chloride form, has a high partition coefficient for Cu. Sample aliquots were loaded onto 1 mL of the AG1-X8 (200-400 mesh) resin on 0.4 × 7 cm Teflon columns and matrix elements were eluted in 5 mL of 6 M HCl. The Cu was then eluted in a further 10 ml of 6 M HCl. Iron was then eluted taken in 4 mL of 0.5 M HCl.

Samples were evaporated to dryness and the whole procedure was repeated to further purify Cu and Fe. The final purified Cu and Fe fractions were taken up in 0.32 M HNO3 and made up to 300 ppb and 2 ppm, respectively, and doped with 300 ppb and 5 ppm of Ni, respectively, for analysis.

Copper isotope analysis was performed on a ThermoScientific Neptune Plus Multi-Collector Inductively-Coupled-Plasma Mass-Spectrometer (MC-ICP-MS) at the Institut de Physique du Globe, Paris. Samples were introduced into the instrument using an ESI PFA microflow nebuliser (100 μl min -1 flow rate) running into a quartz spray chamber following the procedure of [START_REF] Sossi | Combined separation of Cu, Fe and Zn from rock matrices and improved analytical protocols for stable isotope determination[END_REF]. The instrument was operated at low resolution (m/Δm ~ 450, where Δm is defined at 5 % and 95 % of peak height), with the 65 Cu and 63 Cu beams collected in the C (central) and L2 Faraday cups respectively.

The Ni masses ( 60 Ni, 61 Ni, 62 Ni) were collected in cups L3, L2 and L1, respectively.

Under typical running conditions, a 300 ppb Cu solution generated a 0.06-0.08 nA ion beam (6-8 V total signal using 10 11 Ω resistors). To ensure sufficient counting statistics on the 62 Ni/ 60 Ni ratio, the 62 Ni signal was kept above 0.5 V. Instrument background signal (typically <10 mV 63 Cu) was measured at the beginning of each analytical session.

The total procedural blank contained ~1 ng Cu, which equates to <1 % of the Cu sample analyte. Isotope ratios were measured in static mode, with each measurement consisting of 30 cycles of 4.194 second integrations, with a 1 second idle time. Ratios were calculated in the Thermo Neptune Data Evaluation software, which discarded any outliers at the 2-sigma confidence level. To correct for instrumental mass bias, isotope measurements were calculated using the standard sample bracketing protocol relative to the NIST SRM976 standard and corrected for by using the 62 Ni/ 60 Ni ratio using the exponential law. Variations in Cu ratios are defined using the delta notation δ 65 Cu as follows: δ 65 Cu = [( 65 Cu/ 63 Cusample/ 65 Cu/ 63 CuSRM976) -1] × 1000. Analysis of two separate digestions of USGS standard reference material BHVO-2 gave δ 65 Cu of 0.07 ± 0.06‰ (2SE), in good agreement with literature data (Savage et al., 2015;[START_REF] Moynier | The isotope geochemistry of zinc and copper[END_REF].

Iron isotope measurements follow the protocol of [START_REF] Sossi | Combined separation of Cu, Fe and Zn from rock matrices and improved analytical protocols for stable isotope determination[END_REF]. Solutions were diluted to 2 ppm, doped with 5 ppm of Ni, and aspirated through a 100μL/min glass nebulizer into a Scott Double Pass-Cyclonic spray chamber coupled to the ThermoScientific Neptune Plus MC-ICP-MS. Forty integrations of 4.194 s were performed on the iron shoulder of the peak with medium resolution slits, affording a resolving power, m/∆m, of 8000; a necessity given the polyatomic ArN, ArO and ArOH interferences that otherwise over-lap with 54 Fe, 56 Fe and 57 Fe respectively. This set-up gave signal intensities of 0.8V for 57 Fe and 1V for 61 Ni, where Ni corrects for mass bias using the exponential law. The procedural blank for Fe was ≈10 ng and resulted in negligible blanks for most of the samples analyzed. Samples were bracketed against the IRMM-014 standard, yielding the delta value: δ x Fe (‰) = ([ x Fe/ 54 Fe]sample/[ x Fe/ 54 Fe]IRMM-014 -1) × 1000, where x is equal to 56 Fe or 57 Fe. All uncertainties reported on the isotope analyses are the standard deviation of replicates. The total procedural external uncertainty is ±0.02 (SE) δ 56 Fe based on processing and analysis of standard rock powders. Data for standard ETH Hematite, δ 56 Fe = +0.51 ± 0.02‰, δ 57 Fe = +0.75 ±0.02‰, agrees with compiled values [START_REF] Poitrasson | On the iron isotope heterogeneity of lithospheric mantle xenoliths: implications for mantle metasomatism, the origin of basalts and the iron isotope composition of the Earth[END_REF].

Results

Copper and Fe isotope and abundance results are presented in Tables 1 and2 and Cu data is shown in Figure 1. Bulk samples of 66095 have concentrations of Cu of 4.7 and 6.3 µg g -1 , in good agreement with ICP-MS data (3.6-5.4 µg g -1 ), with δ 65 Cu of 0.70 and 0.79‰. Residue samples generally have a lower range of Cu abundances (2-4.3 µg g - 1 ; except residue J14 at 18.5 µg g -1 ) and δ 65 Cu of between 0.59 and 0.77‰. Leaches and etches of HCl and HF-HNO3 have a range in Cu abundances (2.5-11.6 µg g -1 ) and a wide range in δ 65 Cu of between 0.63 and 1.38‰. None of the water leaches analyzed for Fe and Zn were analyzed for Cu isotopes due to low total Cu contents.

Iron isotope and abundance results are presented in Figures 2 and3. All data are mass-dependent in δ 56 Fe-δ 57 Fe space conforming to δ 57 Fe (and its uncertainty) ≈1.5 × δ 56 Fe. Iron abundance results obtained on purified Fe fractions for MC-ICP-MS agree well with ICP-MS solution data (Table 1), except for a single 1M HCl leach for 66095, 430. Bulk samples of 66095 have between 2.2 and 4.8 wt.% FeO and a range of δ 56 Fe between 0.14 to 0.26‰. Residue samples have lower FeO contents (1.6-2.6 wt.%) and a more restricted range of δ 56 Fe (0.10 to 0.15‰). Leaches and etches of HCl and HF/HNO3

give the widest range of FeO contents (2.3-24.6 wt.%) and heavier δ 56 Fe (0.15 to 0.19‰) than associated residues. Water leaches have a range in FeO contents (4.0-8.6 wt.%) and the lightest δ 56 Fe for the dataset (-0.05 to 0.04‰).

Copper and iron isotopes in 66095 show a much larger relative range in isotopic compositions than for Zn in the same samples. Zinc abundances vary dramatically in whole-rocks, leaches/etches and residues (14.8 to >10,000 µg g -1 ), but Zn isotopic compositions are generally consistent (-13.5 ±0.3‰, 1SD, n = 12), except for in the water leaches (-13.3 to -8.1‰). None of the measured isotope systems (Fe, Cu, Zn) are correlated with each other for the data set as a whole, or for the bulk, residue or leachate fractionations. Mass balance reconstruction of leachate/etchate and residue experiments versus bulk rock samples of 66095 generally agree well (Table 2), with any disagreement likely relating from modal effects between samples, where sample sizes were nonrepresentative of the bulk composition of 66095.

Discussion

Copper and iron isotope composition of 66095 and the Moon

Prior to discussing the distribution of moderately volatile elements in the Rusty Rock, 66095, it is useful to place the Cu and Fe isotope compositions in context with 10 lunar compositions. In the first instance, while there is a meteoritic component in the Rusty Rock, the amount of impact contamination is not enough to explain either the Cu or Fe contents of 66095 [START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF]. Instead, the Moon provides a key comparison with the composition of the Earth, with prior work indicating strong geochemical similarities between the two bodies [START_REF] Ringwood | Basaltic magmatism and the bulk composition of the Moon[END_REF][START_REF] O'neill | The origin of the Moon and the early history of the Earth-A chemical model. Part 1: The Moon[END_REF] values of +0.03 ±0.03‰ [START_REF] Craddock | Abyssal peridotites reveal the nearchondritic Fe isotopic composition of the Earth[END_REF] and +0.05 ± 0.01‰ [START_REF] Sossi | Iron isotope systematics in planetary reservoirs[END_REF].

The estimated BSM δ 56 Fe value from the Mg-suite samples is ~0.07‰ lighter than the low-Ti mare basalt average of +0.12 ± 0.02‰ [START_REF] Liu | Oxygen and iron isotope constraints on near-surface fractionation effects and the composition of lunar mare basalt source regions[END_REF]; Figure 3), reflecting iron isotopic fractionation of melts from the lunar interior during magmatic differentiation processes (see discussion in [START_REF] Sossi | Chemical and isotopic kinship of iron in the Earth and Moon deduced from the lunar Mg-suite[END_REF].

As a comparison for the Cu isotopic composition, we compiled data from the literature for a range of lunar rock types, including regolith or soil samples, mare basalts and pyroclastic glass beads that collectively span a wide-range of δ 65 Cu values (-1 to +4.5‰) and Cu concentrations (2.7 to 84 µg g -1 ; Figure 1). Lunar soil samples are consistently isotopically heavy for both δ 65 Cu (+0.3 to +4.5‰) and δ 66 Zn (+2.2 to +6.4‰), with generally low Cu abundances (3 to 84 µg g -1 ); these characteristics of lunar soils have previously been attributed to impact gardening and sputtering effects [START_REF] Herzog | Isotopic and elemental abundances of copper and zinc in lunar samples, Zagami, Pele's hairs, and a terrestrial basalt[END_REF]. The pyroclastic glass beads (74001, 74220) have typically higher Cu abundances (average = ~20 µg g -1 ) and isotopically lighter δ 65 Cu (0.15 to -1‰) and δ 66 Zn compositions than most basalts, which reflect addition of isotopically light Cu-and Zn-rich condensate material to these deposits [START_REF] Moynier | Isotopic composition of zinc, copper, and iron in lunar samples[END_REF][START_REF] Herzog | Isotopic and elemental abundances of copper and zinc in lunar samples, Zagami, Pele's hairs, and a terrestrial basalt[END_REF][START_REF] Kato | Extensive volatile loss during formation and differentiation of the Moon[END_REF][START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF]. Mare basalts span a range of Cu abundances (~2.7 to 26 µg g -1 ) exceeding abundances for the most primitive mare basalts [START_REF] Day | Geochemical constraints on residual metal and sulfide in the sources of lunar mare basalts[END_REF] [START_REF] Wang | An iron isotope perspective on the origin of the nanophase metallic iron in lunar regolith[END_REF]. These results indicate that impact vaporization processes can lead to enrichment of heavy Fe isotopes in the residues and light Fe isotopes in the vapor, consistent with the Fe isotopic variations in components of 66095 and its origin as an impact melt breccia.

Further experiments would be valuable to elucidate this effect.

Mass-balance calculations for leaching and residue experiments yield similar values to bulk samples of 66095 (Table 2), with 3.0 ±1.3 wt.% FeO (range = 2.0-4.8 wt.%), 5.4 ±3.1 ppm Cu (range = 3-12 ppm), with average δ 56 Fe of 0.15 ± 0.05‰

(weighted mean = 0.16‰) and δ 65 Cu of 0.72 ±0.14‰ (weighted mean = 0.78‰). The new results for Cu and Fe isotope compositions of 66095 show that they are not particularly anomalous relative to baseline lunar compositions defined by mare basalts (δ 65 Cu = +0.92 ± 0.16‰; δ 56 Fe = +0.12 ± 0.02‰). In the following sections, we outline the importance of these observations for volatile element behavior in and on the Moon.

Origin of volatile element enrichments in the Rusty Rock, 66095

The fine-grained subophitic to ophitic polymict breccia 66095, is the archetypal lunar 'Rusty Rock', recognized as an important sample during initial characterization with the discovery of rust coloured stains on its surface and interior [START_REF] Bass | Description of 66095[END_REF][START_REF] Taylor | Rust" in the Apollo 16 rocks[END_REF]El Goresy et al., 1973). The 'rusty' character of 66095 is due to the presence of akaganéite (FeOOH; [START_REF] Taylor | Rust" in the Apollo 16 rocks[END_REF] and lawrencite (FeCl2; [START_REF] Shearer | Chlorine distribution and its isotopic composition in "rusty rock" 66095. Implications for volatile element enrichments of "rusty rock" and lunar soils, origin of "rusty" alteration, and volatile element behavior on the Moon[END_REF].

Subsequently, greater than twenty-five Apollo 16 samples have been identified as having rusty rims of iron hydroxide phases around FeNi metal, as FeO(OH) polymorphs (akaganéite, βFeO[OH,Cl]) [START_REF] Colson | Mineralization on the moon? Theoretical considerations of Apollo 16 'rusty rocks', sulfide replacement in 67016, and surface-correlated volatiles on lunar volcanic glass[END_REF][START_REF] Jean | Rusty Rocks' from the Moon: Volatile-Element Contributions from Meteorites[END_REF]. These samples come from nearly all sampled stations of the Apollo 16 mission to the Cayley Plains and include rake samples in soils (68501, 68441), regolith breccias (60016,61135,65095,66035,66036), polymict or dark matrix breccias (60255, 66055, 69935), impact melt rocks and breccias (60625,63585,64455,64567,66095), and anorthosite and anorthositic breccias (65326,67016,67455). The presence of rusty alteration both within different rock types from the Apollo 16 site, and from different locations across the site suggests a common process responsible for the alteration.

In addition to the pervasive low temperature, volatile-rich oxyhydrated mineral assemblages, 66095 is also enriched in a volatile component, including elevated abundances of Bi, Br, Cd, Cl, Ge, I, 204 Pb, Sb, Tl and Zn compared with other lunar samples [START_REF] Krahenbuhl | Volatile elements in Apollo 16 samples: Implications for highland volcanism and accretion history of the moon[END_REF][START_REF] Wanke | Multielement Analysis of Samples from Highland Breccia 66095: A contribution to the "Rusty Rock[END_REF][START_REF] Jovanovic | Aspects of the history of 66095 based on trace elements in clasts and whole rock[END_REF][START_REF] Ebihara | Trace elements in 59 mostly highland moon rocks[END_REF][START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF]. Amongst these elements, the chlorine composition of 66095 is isotopically heavier (δ 37 Cl = +14.0 to +15.6‰) than any known terrestrial rock samples (typically -3 to +3‰), and consistent with δ 37 Cl values (+5.6 to +15.7‰) for lunar rocks and soils around the Apollo 16 site [START_REF] Shearer | Chlorine distribution and its isotopic composition in "rusty rock" 66095. Implications for volatile element enrichments of "rusty rock" and lunar soils, origin of "rusty" alteration, and volatile element behavior on the Moon[END_REF]. The Rusty Rock also has one of the most extreme, isotopically light Zn compositions measured for any Solar System material (δ 66 Zn = -13.5‰; [START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF], again inconsistent with a terrestrial origin, where δ 66 Zn is typically between 0.1 and 0.4‰ in terrestrial rocks [START_REF] Paniello | Zinc isotopic evidence for the origin of the Moon[END_REF][START_REF] Moynier | The isotope geochemistry of zinc and copper[END_REF].

Amongst the volatile elements, the U-Pb and Rb-Sr isotope systems are tracers par excellence of volatile enrichment and depletion since they can both potentially provide chronological information, and, in the case of the U-Pb isotope system, the parent (U) is refractory, and the daughter (Pb) is volatile, whereas the opposite is true for the Rb-Sr isotope system. The lead isotopic composition of 66095 shows that greater than 85% of Pb is unsupported in the rock, identifying a source with high-μ ( 238 U/ 204 Pb ≥ 570;

Nunes [START_REF] Nunes | Excess lead in "Rusty Rock" 66095 and implications for an early lunar differentiation[END_REF]. The age defined from 207 Pb-206 Pb chronology (4.01 ±0.06

Ga) is identical within uncertainty of the 87 Rb-87 Sr age (4.06 ±0.24 Ga), with the defined 87 Sr/ 86 Sr initial of 0.69909 ±5, consistent with lunar origins for both isotope systems [START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF].

Strontium and Pb isotope compositions suggest a long-term volatile-depleted source for 66095, in apparent contradiction to the enrichment in volatile components in the sample (e.g., Bi, Br, Cd, Cl, Ge, I, 204 Pb, Sb, Tl, Zn). These geochemical characteristics can be reconciled by outgassing of an already volatile-depleted source within the Moon to generate the volatile enriched character of 66095 [START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF].

Such a model is consistent with fumarolic activity (e.g., [START_REF] Krahenbuhl | Volatile elements in Apollo 16 samples: Implications for highland volcanism and accretion history of the moon[END_REF][START_REF] Nunes | Excess lead in "Rusty Rock" 66095 and implications for an early lunar differentiation[END_REF], where lawrencite was deposited at between 650˚C to 570˚C [START_REF] Shearer | Chlorine distribution and its isotopic composition in "rusty rock" 66095. Implications for volatile element enrichments of "rusty rock" and lunar soils, origin of "rusty" alteration, and volatile element behavior on the Moon[END_REF] and sphalerite was deposited at between 200˚C and 600˚C [START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF] from an H-poor gas phase. [START_REF] Shearer | Chlorine distribution and its isotopic composition in "rusty rock" 66095. Implications for volatile element enrichments of "rusty rock" and lunar soils, origin of "rusty" alteration, and volatile element behavior on the Moon[END_REF] further proposed that the low H gas phase was metal chloride bearing, depositing Zn, Cu, Pb and Fe. In detail, however, the cause of Zn and Pb volatile enrichment must be distinct from Cu and Fe in 66095, based on stable isotope composition. The 'rusty' character and volatile element enrichment of 66095 is therefore consistent with volatile enrichment through fumarolic activity -likely during impact processes -from a volatile-poor source in the Moon, as opposed to partly to fully representing terrestrial alteration products, as had been suggested previously [START_REF] Epstein | D/H and O-18/O-16 ratios of H 2 O in the 'rusty' breccia 66095 and the origin of 'lunar water[END_REF][START_REF] Taylor | Beta-FeOOH, akaganeite, in lunar rocks[END_REF].

Causes of Fe, Cu, Pb and Zn isotopic and abundance variability in 66095

A notable feature of the new Cu and Fe isotope data for 66095 is that the values for bulk samples, residues after leaching and HF/HNO3 treatment samples generally all lie within or close to the range of mare basalts (Figures 1 and3).

To compare the relative enrichments of elements in 66095, data for Cl from [START_REF] Shearer | Chlorine distribution and its isotopic composition in "rusty rock" 66095. Implications for volatile element enrichments of "rusty rock" and lunar soils, origin of "rusty" alteration, and volatile element behavior on the Moon[END_REF], Sb, Se, Te, Ag, Br, Bi, Cd and Tl from [START_REF] Krahenbuhl | Volatile elements in Apollo 16 samples: Implications for highland volcanism and accretion history of the moon[END_REF] and data for all other elements from [START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF], are compared with the average lunar volatile depletion trend (Figure 4). A notable aspect of this plot is that two distinct groups of moderately volatile elements (here defined as elements with Tc50% < Fe) can be distinguished; those that are equally or more depleted than the average lunar volatile depletion trend (Bi, Se, Te, Ge, Cu, Ag, Sb, Mn, P, Cr) and those that are significantly more enriched compared to this trend (Tl, Br, Cd, Sn, Zn, Pb, Rb, Cs, Ga, B, Cl, Li).

Concentrations of moderately volatile elements (e.g., Cr, Mn, Cu, Rb, Cs, Zn) measured on different aliquots of 66095 can vary significantly (e.g., [START_REF] Krahenbuhl | Volatile elements in Apollo 16 samples: Implications for highland volcanism and accretion history of the moon[END_REF][START_REF] Wanke | Multielement Analysis of Samples from Highland Breccia 66095: A contribution to the "Rusty Rock[END_REF][START_REF] Ebihara | Trace elements in 59 mostly highland moon rocks[END_REF] [START_REF] Wanke | Multielement Analysis of Samples from Highland Breccia 66095: A contribution to the "Rusty Rock[END_REF]this study) and the mass balance for Fe can therefore be fully accounted for by these phases. Metal phases are the dominant source of Cu, where Cu solubility in sphalerite is low [START_REF] Scott | Chemical behaviour of sphalerite and arsenopyrite in hydrothermal and metamorphic environments[END_REF], and FeNi metal in some Apollo 16 impact melt rocks have up to 0.5 wt.% Cu [START_REF] Mcintosh | Insights into Impactor Populations Striking the Moon from Melt Coat and Regolith Meteorite Compositions[END_REF]. Even assuming the average Cu content of FeNi metal grains in impact melt rocks of ~0.1 wt.% Cu, 1.2 modal% FeNi metal in 66095 would give ~12 ppm Cu in bulk samples of 66095, which is well within the range of Cu contents measured for the 'Rusty Rock' (Table 1).

The second reason for different distributions of moderately volatile elements in 66095 is due to the role of condensate and vapor deposition, where the enriched MVE group are presumed to have been primarily enriched by such a process. As noted previously, sphalerite and lawrencite were deposited between 200 and 650°C, which would be consistent, for example, with deposition of discrete grains of (Zn,Fe)S or PbS (?) and (Fe,Ni)Cl2. While some elements appear to be dominantly controlled by primary phases, leaching and etching experiments have the potential to reveal possible condensate or vapour additions, one example being the water leaches measured for Fe isotope compositions (Table 1). These water leaches are all isotopically light with respect to Fe (δ 56 Fe = 0.04 to -0.05‰) and have low total abundances of Fe (0.7 to 20 µg g -1 ). The low δ 56 Fe do not reflect analytical blanks, which represent less than 1.4% of the total measured Fe in the samples. The water leach iron isotope compositions are also massdependent. Although an extremely minor component of 66095, there appears to be isotopically light Fe within or on 66095, and this may originate from FeCl salts, either directly, or from the breakdown of lawrencite in H2O, where water leaches have high concentrations of both Fe and Ni (c.f., Table S2 of [START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF]. Examples of location of elements within 66095 and how they were inherited in the sample are given in Figure 5, where primary grains of FeNi metal -hosts to both Fe and Cu -are distinct from the secondary sphalerite and veins and infilled fractures of Cl-rich materials.

The composition of moderately volatile elements in the 'Rusty Rock' would imply that it formed at lower temperatures away from a fumarolic vent, consistent with lawrencite and sphalerite thermometry [START_REF] Shearer | Chlorine distribution and its isotopic composition in "rusty rock" 66095. Implications for volatile element enrichments of "rusty rock" and lunar soils, origin of "rusty" alteration, and volatile element behavior on the Moon[END_REF][START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF]. The distribution of moderately volatile trace elements in the 'Rusty Rock', 66095, appear to follow the expected trend of element deposition from a lunar volcanic gas. Renggli et al.

(2017) calculated the speciation of Ni, Fe, Cu, Ga, Zn and Pb for a lunar volcanic gas composition at 2 log units below the Iron-Wüstite buffer over a range of temperatures (500 to 1500°C and pressures (10 -6 to 1 bar). For a lunar composition gas, the major volatiles were likely to be CO, H2, H2S, COS and S2. These authors concluded that deposition with decreasing temperature and increasing pressure occurs in the order: Ni ≈ Fe > Cu > Ga > Zn > Pb. In general, at 10 -6 bar, these metals exist as monatomic gases at higher temperatures, whereas the gaseous chloride species of Cu and Fe become predominant below 800 °C. As such, native metals tend to precipitate close to the volcanic or fumarolic vent at higher temperatures, with sulfide or chloride species distributed further away. The composition of moderately volatile elements in the 'Rusty Rock' would imply that it formed at lower temperatures away from a fumarolic vent, consistent with the lawrencite and sphalerite thermometry (Figure 4). Iron is present as chlorides and oxy-hydroxides that are only stable at low temperatures (<700 °C), implying the persistence of iron in the vapour below 1200-1300 °C as modelled by [START_REF] Renggli | Volcanic gas composition, metal dispersion and deposition during explosive volcanic eruptions on the Moon[END_REF]. The fact that the Cu and Fe isotope composition of the Rusty Rock is within the range of mare basalts leaves two options. First, that Cu and Fe were not transported in the gas and are instead dominated by inherent mineralogical components, and second that the Cu and Fe budget of the rock condensed entirely and was thus associated with negligible isotope fractionation with respect to its source.

The first option is consistent with the observation that Cu and Fe are not enriched with respect to mare basalts (Figure 4). However, that Fe-rich and isotopically light deposits occur on the surface from water leaches attests to some transport of Fe (and the more volatile Cu) in the vapor phase. As discussed above, the quantity that these surface deposits comprise of the total Cu and Fe budget of the rock is minor, and the leachates are not significantly fractionated relative to the bulk rock dissolution. This implies that, although Cu and Fe were transported in the vapor, they were not sufficiently enriched to modify the composition of the bulk rock. Moreover, that the leachates have compositions overlapping with mare basalts argues that the budget of Cu and Fe in the vapor suggests that they condensed fully from the vapor phase such that their isotopic composition should reflect that of their sources (option 2). Therefore, the lunar source from which the vapour was derived was similar in nature to that of mare basalts. Therefore, a distinct, isotopically-fractionated, volatile-enriched reservoir in the lunar mantle in unlikely.

The isotopically 'normal' nature of Cu and Fe in sample 66095 is seemingly atodds with the strongly fractionated Zn isotope composition (-13.6±0.3 ‰) in the same sample. A possible explanation for the distinct behavior of Zn relates to its volatility; Zn (and Pb) is calculated to precipitate from a gas of lunar composition at lower temperatures than are Cu and Fe [START_REF] Renggli | Volcanic gas composition, metal dispersion and deposition during explosive volcanic eruptions on the Moon[END_REF]. Therefore, the strongly negative δ 66 Zn implies condensation of the gas at temperatures at which Zn is only partially condensed, resulting in isotopically light condensates. This temperature must have been sufficiently low to have permitted complete condensation of Cu and Fe and to have stabilized Fe-chlorides. Together, these constraints imply precipitation of the gas phase below 900 °C but above 700 °C (at total pressures of 10 -6 bar and IW-2). That Cu and Fe elements are not enriched in the sample supports lower abundance in the gas phase relative to the source rock. By contrast, that Zn (and Pb) are enriched points to their higher relative abundance in the gas phase compared to the sample, even if Zn has only undergone partial condensation. This scenario would predict strong mass-dependent isotopic fractionation in elements more volatile than Zn, such as Pb, and others that are enriched in sample 66095 (Tl, Cd; Figure 4). Gallium isotopes may be particularly exacting because Ga is predicted to condense at temperatures between those of Cu and Zn.

Implications for volatile reservoirs at the surface and in the lunar interior

The Rusty Rock, 66095, is one of the most volatile-rich rocks recovered from the Moon, having experienced modification by fumarolic activity resulting in the enrichment in some volatile and moderately volatile elements [START_REF] Krahenbuhl | Volatile elements in Apollo 16 samples: Implications for highland volcanism and accretion history of the moon[END_REF][START_REF] Nunes | Excess lead in "Rusty Rock" 66095 and implications for an early lunar differentiation[END_REF]. The source of these volatiles, however, is quite volatile-poor, being particularly evident from combined Zn, Cl, Pb and 87 Sr/ 86 Sr isotope data indicating addition of condensate material with isotopically heavy Cl, isotopically light Zn, low long-term Rb/Sr and unsupported Pb [START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF]. The high Zn content and extremely isotopically light δ 66 Zn are particularly notable features of 66095, making the sample distinct from all other lunar rocks. Here we have shown that for Fe and Cu isotopes, 66095 is not particularly anomalous compared with mare basalts, with these isotope systems being controlled by Fe and Cu within FeNi metal and/or silicate phases within the sample, rather than from phases introduced by fumarolic activity (e.g., sphalerite, Cl in veins). These observations have two important implications, the first relating to volatile-rich pyroclastic glass beads, and the second to the distribution of volatile elements on the lunar surface.

The pyroclastic glass beads (15426, 74220) are volatile-rich samples from the Moon that were formed by fire fountaining and have high Cu (7 to 32 ppm) and Zn (50 to 230 ppm) concentrations and isotopically light Cu (δ 65 Cu = +0.1 to -1‰) and Zn (δ 66 Zn = -1‰ to -4‰) that correlate with bead size [START_REF] Herzog | Isotopic and elemental abundances of copper and zinc in lunar samples, Zagami, Pele's hairs, and a terrestrial basalt[END_REF][START_REF] Kato | Extensive volatile loss during formation and differentiation of the Moon[END_REF]. The Zn and Cu isotope compositions in these samples reflect condensates on the surfaces of the beads, as there are no phases dominantly controlling Cu or Zn in the samples, and with direct observation of Zn-bearing minerals on the outsides of the beads [START_REF] Ma | Discovery of zinc-rich mineral on the surface of lunar orange pyroclastic beads[END_REF]. The volcanic glasses have been shown to have significant enrichments in volatile elements that are surface correlated (Krahenbuhl, 1980), with lower estimated μ ( 238 U/ 204 Pb = 19 to 55) than mare basalts (300 to 600; [START_REF] Tatsumoto | Origin of lead from green glass of Apollo 15426: A search for primitive lunar lead[END_REF], and high δ 37 Cl in leachates from 74220 (+8.6 to +9.6‰; [START_REF] Sharp | The chlorine isotope composition of the Moon and implications for an anhydrous mantle[END_REF]. The volcanic glasses also have chondritic relative abundances of the HSE on their outer edges [START_REF] Walker | Low abundances of highly siderophile elements in the lunar mantle: evidence for prolonged late accretion[END_REF], with absolute abundances of these elements that are greater than in mare basalts [START_REF] Day | Highly siderophile element constraints on accretion and differentiation of the Earth-Moon system[END_REF][START_REF] Day | Highly siderophile element depletion in the Moon[END_REF]. Collectively, these lines of evidence suggest that the volcanic glass beads have lunar condensate, as well as impactor materials, on their surfaces, both for Zn, as well as for Cu. The information on volatile contents in the Rusty Rock 66095 indicates that such material was likely added during fire fountaining, or after the formation of the glass bead deposits. The new results for Cu in 66095 would therefore suggest that the lunar pyroclastic glass beads are anomalously enriched in a condensate volatile component from a dominantly 'dry' lunar interior.

A volatile-rich lunar surface has been inferred from remote sensing mission data, including Clementine, Lunar Prospector, Lunar Reconnaissance Orbiter (LRO), the Moon Mineralogy Mapper (M 3 ) on Chandrayaan-1, and the Lunar Crater Observation and Sensing Satellite (LCROSS). Data from these missions have been used to identify Hbearing species not only within permanently-shadowed cold traps at polar regions, but also in non-polar regions of the Moon (e.g. [START_REF] Feldman | Fluxes of fast and epithermal neutrons from Lunar Prospector: Evidence for water ice at the lunar poles[END_REF][START_REF] Pieters | Character and spatial distribution of OH/H2O on the surface of the Moon seen by M3 on Chandrayaan-1[END_REF][START_REF] Paige | Diviner lunar radiometer observations of cold traps in the Moon's south polar region[END_REF][START_REF] Colaprete | Detection of water in the LCROSS ejecta plume[END_REF][START_REF] Li | Water on the surface of the Moon as seen by the Moon Mineralogy Mapper: Distribution, abundance, and origins[END_REF]. Most of this volatile

GCA SI LAT

The Rusty Rock 20 component has been attributed to solar wind implantation during agglutinate formation [START_REF] Li | Water on the surface of the Moon as seen by the Moon Mineralogy Mapper: Distribution, abundance, and origins[END_REF]. The 'Rusty Rock' 66095 offers the possibility that a significant fraction of volatiles trapped within some lunar regolith may originate from interior sources and is isotopically strongly fractionated due to the volatile depleted nature of the lunar interior. The fumarolic activity required to form the volatile enriched 'Rusty Rocks' at the Cayley Plains may not be a localized feature, or a temporally limited event, with recent disturbance structures attributed to outgassing occurring at Ina Crater (e.g. [START_REF] Schultz | Lunar activity from recent gas release[END_REF]. Testing what fraction of lunar volatile deposits originate from the interior of the Moon should be possible using isotopic fingerprinting of solar wind implantation versus kinetic isotopic fractionation during vapour-phase and condensate reactions.

Conclusions

Copper and iron isotope and abundance compositions measured in bulk-rocks, and Zn isotopes demonstrate that the phases hosting these elements can play an important role in dictating isotopic composition, leading to apparently 'mixed messages' regarding the source of volatiles in lunar samples. (1991), and red dashed line is the predicted deposition of metals within a lunar fumarolic/volcanic gas distal from the source from [START_REF] Renggli | Volcanic gas composition, metal dispersion and deposition during explosive volcanic eruptions on the Moon[END_REF]. Condensation temperature values are from [START_REF] Lodders | Solar system abundances and condensation temperatures of the elements[END_REF] and CI chondrite normalization is from [START_REF] Mcdonough | The composition of the Earth[END_REF]. FeO, Cu and all Zn abundances and isotopic data were previously reported in [START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF]. US = ultra-sonification

Figures and Figure Captions

  residues and acid leaches span a relatively limited range of compositions (3.0 ±1.3 wt.% FeO [range = 2.0-4.8 wt.%], 5.4 ±3.1 ppm Cu [range = 3-12 ppm], average δ 56 Fe of 0.15 ± 0.05‰ (weighted mean = 0.156‰) and δ 65 Cu of 0.72 ±0.14‰ (weighted mean = 0.78‰). The stable isotope compositions of Cu and Fe are similar to averages of mare basalts (δ 65 Cu = +0.92 ±0.16‰; δ 56 Fe = +0.12 ± 0.02‰) and are therefore less extreme compositional variations than previously measured for δ 66 Zn (-13.5 ±0.3‰), δ 37 Cl (+14 to +15.6‰). Combined with the high 206 Pb/ 204 Pb and low 87 Sr/ 86 Sr measured in 66095, these results are consistent with the enrichment in volatile elements in the 'Rusty Rock' by fumarolic activity and preferential enrichment of volatiles elements from a cooling gas originating from a volatile-poor lunar interior. We find that the enrichment in Tl, Br, Cd, Sn, Zn, Pb, Rb, Cs, Ga, B, Cl, Li relative to Bi, Se, Te, Ge, Cu, Ag, Sb, Mn, P, Cr and Fe is consistent with volcanic outgassing models, and indicates that 66095 may have formed distal from the original source of the gas. The evidence for impact brecciation and the moderately elevated HSE contents of 66095 are consistent with fumarolic activity in the vicinity of the Apollo 16 site at the Cayley Plains, induced by impact heating. The elucidation of the volatile-rich character of 66095 explains the 'rusting' and alteration on the sample, through fumarolic activity, alteration and deposition of volatile and moderately volatile elements, as well as demonstrating that volatile-rich rocks can occur on the lunar surface from outgassing of the volatile-poor lunar interior. Our results for Cu

Figure 1 :Figure 3 :Figure 4 :

 134 Figure1: Copper content versus Cu isotopic composition for compositions measured in 66095. Shown is the lunar mare basalt average estimate filtering samples with less than 10 µg g -1 Cu, from a compilation of published (pub) data from[START_REF] Moynier | Isotopic composition of zinc, copper, and iron in lunar samples[END_REF],[START_REF] Herzog | Isotopic and elemental abundances of copper and zinc in lunar samples, Zagami, Pele's hairs, and a terrestrial basalt[END_REF][START_REF] Lindsay | Elemental and Isotopic Abundances of Fe, Cu and Zn in Low-Ti Basalts[END_REF]. PGB are lunar pyroclastic glass beads.

  . For example, Li, O, Si, Mg, Ca, Ti, Fe, and Sr stable isotopic compositions for the Earth and Moon are all identical within analytical uncertainties (e.g.,[START_REF] Spicuzza | Oxygen isotope constraints on the origin and differentiation of the Moon[END_REF][START_REF] Liu | Oxygen and iron isotope constraints on near-surface fractionation effects and the composition of lunar mare basalt source regions[END_REF][START_REF] Moynier | Sr stable isotope composition of Earth, the Moon, Mars, Vesta and meteorites[END_REF][START_REF] Sedaghatpour | Magnesium isotopic composition of the Moon[END_REF][START_REF] Valdes | The nature of Earth's building blocks as revealed by calcium isotopes[END_REF][START_REF] Day | Evidence for high-temperature fractionation of lithium isotopes during differentiation of the Moon[END_REF][START_REF] Millet | Titanium stable isotope investigation of magmatic processes on the Earth and Moon[END_REF][START_REF] Young | Oxygen isotopic evidence for vigorous mixing during the Moon-forming giant impact[END_REF][START_REF] Sossi | Chemical and isotopic kinship of iron in the Earth and Moon deduced from the lunar Mg-suite[END_REF]. For moderately

volatile elements such as S, Cl, K and Zn, however, the Moon is highly distinctive compared with Earth (e.g.,

[START_REF] Day | Geochemical constraints on residual metal and sulfide in the sources of lunar mare basalts[END_REF] Moynier, 2014, Wang and[START_REF] Wang | Potassium isotopic evidence for a high-energy giant impact origin of the Moon[END_REF]

. To date, there are limited Cu isotopic data available for lunar rocks and therefore the composition of the bulk silicate Moon (BSM) is not well-constrained, while the BSM δ 56 Fe composition has been estimated from lunar Mg-suite rocks at +0.05 ± 0.02‰

[START_REF] Sossi | Chemical and isotopic kinship of iron in the Earth and Moon deduced from the lunar Mg-suite[END_REF]

; indistinguishable to slightly heavier than bulk silicate Earth (BSE)

  , and have δ 65 Cu values between -0.1 and 2.0‰.It has previously been assumed that mare basalts are proxies for lunar mantle Zn isotope compositions (e.g.,[START_REF] Paniello | Zinc isotopic evidence for the origin of the Moon[END_REF]. Making a similar assumption for Cu, pristine mare basalts should have low Cu. This is because Cu content is predicted to be low in the lunar mantle, and hosted within sulfide phases[START_REF] O'neill | The origin of the Moon and the early history of the Earth-A chemical model. Part 1: The Moon[END_REF]. Sulfide exhaustion in the lunar mantle occurs after around 8% partial melting due to low S within the range of lunar mare basalt values for δ 65 Cu and δ 56 Fe (or δ 57 Fe) and Cu concentrations. The only materials from 66095 that show values significantly outside of these ranges are the isotopically heavy bulk breccia sample (66095, 430), and the isotopically light water leach treatments for iron isotopes. For the water leaches, it is likely that they accessed soluble and isotopically light FeCl salts, or akaganéite.The heavy Fe isotopic value in 66095, 430 relates to the highest Fe content of the dataset and is consistent with sampling of impact-generated Fe-metal grains formed by partial impact-vaporization and preferential loss of light Fe isotopes, as proposed previously by[START_REF] Wang | An iron isotope perspective on the origin of the nanophase metallic iron in lunar regolith[END_REF]. Prior work on terrestrial analog systems have demonstrated that large (2-3‰) Fe isotope fractionations occur due to redox reactions between ferrous and ferric species (e.g.,[START_REF] Hill | Modeling the effects of bond environment on equilibrium iron isotope fractionation in ferric aquo-chloro complexes[END_REF][START_REF] Polyakov | New data on equilibrium iron isotope fractionation among sulfides: Constraints on mechanisms of sulfide formation in hydrothermal and igneous systems[END_REF][START_REF] Syverson | Fe isotope fractionation between chalcopyrite and dissolved Fe during hydrothermal recrystallization: An experimental study at 350° C and 500 bars[END_REF]. However, in the case of the Moon, where the majority of Fe speciation is considered to be ferrous (Fe 2+ ) or native (Fe 0 ), such fractionations are likely to be of lower relevance. Theoretical studies indicate that changes in bond partners (i.e., different ligands or coordination numbers) should result in significant isotopic fractionation, but conditions similar to those attained on airless bodies have not been well-constrained. Empirical stidy of nanophase iron (npFe 0 ) show large enrichments in the heaviest Fe isotopes (δ 56 Fe up to 0.71%) compared with lunar mare basalts

contents, leading to the prediction that low Cu contents occur in primary lunar mantle melts (<10 µg g -1 ;

[START_REF] Day | Geochemical constraints on residual metal and sulfide in the sources of lunar mare basalts[END_REF]

. Mare basalts with low Cu contents have δ 65 Cu = +0.92 ±0.16‰. This composition is significantly isotopically heavier than typical terrestrial igneous rock compositions (-0.07 to +0.16‰), or the BSE estimate (+0.07 ±0.10‰; 2 S.D.;

Savage et al., 2015)

. The heavier estimated δ 65 Cu of lunar mare basalt sources relative to the BSE is similar to the differences observed for Rb, Cl, K, Zn and S isotopes in the Moon, and consistent with high-temperature processing implied by the depletion in moderately volatile elements in the lunar interior compared with the terrestrial mantle

[START_REF] Day | Evaporative fractionation of volatile stable isotopes and their bearing on the origin of the Moon[END_REF][START_REF] Wang | Potassium isotopic evidence for a high-energy giant impact origin of the Moon[END_REF][START_REF] Pringle | Rubidium isotopic composition of the Earth, meteorites, and the Moon: Evidence for the origin of volatile loss during planetary accretion[END_REF]

.

It has previously been shown that 66095 is depleted in the heavier isotopes of Zn, distinguishing it from mare basalt compositions

[START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF]

. It is therefore remarkable that bulk sample, residue and acid reagent treatments (HCl, HF-HNO3) of 66095 are broadly

  see TableS2of[START_REF] Day | Late-stage magmatic outgassing from a volatile-depleted Moon[END_REF], but the same general trends are observed no matter which data are used, suggesting that the observation of two groups of depleted and enriched moderately volatile elements (MVE)

	is robust.
	Rusty Rock are olivine (~10 modal %; Fo77), pyroxene (~30 modal %; Wo7En72Fs20 to
	Wo17En65Fs18), and FeNi metal (~1.2 modal %; Lunar Compendium). Components that
	make up 66095 are generally low in FeO (1.4-9.6 wt.%;

Instead of the original description of 66095 being enriched in Bi, Br, Cd, Cl, Ge, I, 204 Pb, Sb, Tl, Zn, we redefine the moderately volatile enrichment as occurring for Tl, Br, Cd, Sn, Zn, Pb, Rb, Cs, Ga, B, Cl, Li (enriched MVE) and that Bi, Se, Te, Ge, Cu, Ag, Sb, Mn, P and Cr are all relatively depleted (depleted MVE), compared with the average lunar depletion trend. There are two likely reasons for the differences in the relative enrichment of depletion of these MVE with 66095. First, some of the depleted MVE group are inherent to the sample, being dominantly located within minerals and phases associated with the breccia and clasts making up 66095, rather than as condensates. This can be demonstrated for Fe, where the dominant Fe-rich phase in the

Table 1 : Iron, copper and zinc isotope data for the 'Rusty Rock' 66095 Sample Lithology Type Experiment Lab ID Mass (g) FeO (wt.%) a FeO (wt.%) δ 56 Fe ±2SE δ 57 Fe ±2SE n Cu µg g -1 a Cu µg g -1 δ 65 Cu ±2SE n Zn µg g -

 1

	1	δ 66 Zn	±2σ	δ 67 Zn	±2σ	δ 68 Zn	±2σ

Table 2 : Mass balance calculations for Fe, Cu and Zn systematics in 66095

 2

	Sample	Experiment	Detail	Lab ID Mass (g) Fraction ∑FeO (wt.%)	∑δ 56 Fe	∑Cu (mg g -1 )	∑δ 65 Cu	∑Zn (mg g -1 )	∑δ 66 Zn
	66095,	Bulk		J1	0.01570 100%	4.82	0.15	4.71	0.70	102.1	-13.5
		Exp. 2	Residue (J14)	J12	0.01340 59.8%	2.01	0.13	12.05	0.98	81.1	-13.5
		Exp. 2	1M HCl Leach	J14	0.00900 40.2%
		Exp. 3	Residue (RR)	RR1	0.02741 70.3%	4.87	0.13	4.11	0.63	70.1	-13.5
		Exp. 3	20min H 2 O US	RR2	0.00064	1.6%
		Exp. 3	20min 3N HCl US RR3	0.00610 15.7%
		Exp. 3	2hr 1N HF-HNO 3 RR4	0.00482 12.4%
	66095, (A) Bulk		J2	0.00670 100%	2.15	0.14			397.4	-13.5
	66095, (B) Exp. 1	Residue (LP1)	J3	0.00620 99.6%	2.04	0.15	3.23	0.59	366.5	-13.5
		Exp. 1	30min H 2 O	LP1	0.00002	0.4%
	66095,	Bulk		J4	0.00640 100%	3.94	0.26	6.25	0.79	396.7	-14.0
		Exp. 1	Residue (LP2)	J5	0.00980 99.7%	2.10	0.12	3.06	0.77	267.7	-13.0
		Exp. 1	30min H 2 O	LP2	0.00003	0.3%
		Exp. 2	Residue (J15)	J13	0.00770 98.3%	2.21	0.12	4.21	0.59	384.6	-13.8
		Exp. 2	1M HCl Leach	J15	0.00013	1.7%
	US = ultra-sonification

Acknowledgements

We dedicate this manuscript to the memory of Lawrence A. Taylor who held a fascination with the Rusty Rock, 66095, throughout his career studying the Moon. We thank the NASA curation staff and CAPTEM for samples. Comments by C. Renglli, A. Ruzicka and two anonymous reviewers are gratefully acknowledged. This work was supported by the NASA Emerging Worlds program (NNX15AL74G) and an IPGP Visiting Professor position to JD. FM acknowledges funding from the European Research Council under the H2020 framework program/ERC grant agreement #637503 (Pristine), as well as financial support of the UnivEarthS Labex program at Sorbonne Paris Cité (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02), and the ANR through a chaire d'excellence Sorbonne Paris Cité.