ORIGINAL PAPER
Baseline data for Andean paleomobility research:a radiogenic strontium isotope study of modernPeruvian agricultural soils
Kelly J. Knudson & Emily Webb & Christine White &
Fred J. Longstaffe
Received: 28 November 2012 /Accepted: 11 June 2013# Springer-Verlag Berlin Heidelberg 2013
Abstract While the use of radiogenic strontium isotope valuesto examine paleomobility is increasingly common in the Andes,and beyond, many questions about baseline variability remain.To better understand baseline radiogenic strontium isotope com-positions in the Andes, we present new 87Sr/86Sr values fromPeruvian soil samples. Modern soil samples were collected fromagricultural fields from the following areas in central and south-ern Peru: Arequipa, Atico, Camaná, Chala, Cusco, Ica, Ilo,Lima, Mejía, Moquegua, Nazca, Ocoña, Palpa, Pisco, Puno,Tacna, and Yauca. Samples were partially dissolved to betterapproximate the bioavailable strontium. Radiogenic strontiumisotope values from the partially dissolved soil samples rangefrom 87Sr/86Sr=0.70202 to 0.71894 and, for all soil samples,have a mean of 87Sr/86Sr=0.70773±0.00166 (1σ, n=114). Ingeneral, the 87Sr/86Sr values measured for soil samples collectedfrom modern agricultural fields reflect the expected 87Sr/86Srvalues based on bedrock geology. Comparing our new soil datawith published radiogenic strontium isotope data for bedrock,soil, water, and faunal samples provides constraints on the re-gions in the Andes that can, and cannot, be distinguishedthrough radiogenic strontium isotope analysis.
Keywords Andes . Migration . Residential mobility . Peru .87Sr/86Sr
Introduction
Archaeologists increasingly use isotopic methods, such asradiogenic strontium isotope analysis of archaeological skele-tal and dental elements, to examine paleomobility. However,the best ways to interpret 87Sr/86Sr values as evidence ofresidential mobility and migration are still being investigated.Determining “local” signatures for various regions throughconstruction of radiogenic strontium isotope baselines usingvarious proxies is of utmost importance in the application ofthis method. Here, we investigate variability in radiogenicstrontium isotope ratios of modern soil samples collected fromagricultural fields in southern Peru. We first provide a briefintroduction to the principles of radiogenic strontium isotopeanalysis and its uses in archaeology. We then describe the useof isotopic tracers in Andean paleomobility studies, followedby a discussion of expected 87Sr/86Sr values based on bedrockgeology in the study area. After discussing our materials andmethods, we present new radiogenic strontium isotope data formodern soil samples collected from the following areas incentral and southern Peru: Arequipa, Atico, Camaná, Chala,Cusco, Ica, Ilo, Lima, Mejía, Moquegua, Nazca, Ocoña, Palpa,Pisco, Puno, Tacna, and Yauca. In our concluding sections, weinterpret our baseline data with published data from bedrockand faunal samples to better understand bioavailable 87Sr/86Srvalues in the Andes and discuss the implications of these datafor future paleomobility studies in the Andes and beyond.
Radiogenic strontium isotope analysis in archaeology
Over the past 15 years, the use of isotopic methods toexamine paleomobility has increased dramatically. Whileother isotopic systems can be used to investigate geographicorigins (e.g., White et al. 2009;White et al. 2007), radiogenicstrontium isotope analysis continues to be widely used (seeBentley 2006). Briefly, radiogenic strontium isotope ratios
K. J. Knudson (*)Center for Bioarchaeological Research, School of HumanEvolution and Social Change, Arizona State University,PO Box 872402, Tempe, AZ 85287, USAe-mail: [email protected]
E. Webb :C. WhiteDepartment of Anthropology, The University of Western Ontario,London, ON N6A 5C2, Canada
F. J. LongstaffeDepartment of Earth Sciences, The University of Western Ontario,London, ON N6A 5C2, Canada
Archaeol Anthropol SciDOI 10.1007/s12520-013-0148-1
vary in a given geologic zone according to bedrock age andinitial composition (Faure 1986). This isotopic variability islargely reflected in the soils, plants, and animals in a givengeologic zone (see Bentley 2006). Therefore, 87Sr/86Srvalues of archaeological human remains can be used todetermine the geologic region or regions in which an indi-vidual lived during enamel and bone formation, if “local”strontium sources were consumed and imbibed (Ericson1985; Price et al. 1994a, b).
While paleomobility studies using radiogenic strontium iso-topes have generally focused on human movement, there isalso a growing body of literature on the movement of plantproducts and animals in the past. For example, scholars haveinvestigated reindeer (Rangifer sp.) migration and Neanderthalhunting strategies in Europe (Britton et al. 2009, 2011), cattle(Bos taurus) mobility and husbandry practices in the BritishNeolithic (Viner et al. 2010), Iron Age horse (Equus feruscaballus) exchange and breeding programs in the UK(Bendrey et al. 2009), mountain sheep (Ovis canadensis) hunt-ing practices in western North America (Fisher and Valentine2013), and trade and exchange of deer (Odocoileusvirginianus) and peccary (Tayassuidae sp.) in Mesoamerica(Thornton 2011). In addition to the movement of wild anddomesticated animals in the past, 87Sr/86Sr values have beenused to investigate the trade and exchange of domesticatedgrains (Hordeum vulgare) in the UK (Heier et al. 2009),sources of plant fibers used in Danish Iron Age textiles (Freiet al. 2009b), and maize (Zea mays) in the North AmericanSouthwest (Benson et al. 2003, 2009, 2010; Benson 2010).
Introduction to Andean paleomobility studies
Light stable isotopes have also been used to investigate Andeanpaleomobility, as is described elsewhere (Buzon et al. 2011; Gilet al. 2011; Knudson 2009; Knudson et al. 2012a, b, 2009;Knudson and Price 2007; Knudson and Torres-Rouff 2009;Turner and Armelagos 2012; Turner et al. 2009; Ugan et al.2012; Webb et al. 2013; White et al. 2009). Here, we focus onpublished work using radiogenic strontium isotopes. The ear-liest isotopic work on Andean paleomobility involved theMiddle Horizon (c. AD 500–1100) Tiwanaku polity, wheresubstantial geologic variability ensures that movement betweenthe Tiwanaku capital in the Lake Titicaca Basin and Tiwanaku-affiliated sites in southern Peru, Bolivia, and northern Chile canbe identified (Knudson 2007, 2008; Knudson and Price 2007;Knudson et al. 2004, 2005; Knudson and Torres-Rouff 2009;Lucas 2012; Marsteller et al. 2011; Nado et al. 2012). In theMiddle Horizon Wari polity of Peru, radiogenic strontiumisotope analysis has been used to examine both populationmovement as well as the geographic origins of individualstransformed into trophy heads (Knudson and Tung 2007,2011; Slovak et al. 2009; Tung and Knudson 2008, 2010,2011). More recently, scholars have focused on Early
Intermediate Period and Middle Horizon paleomobility in theNazca Drainage of southern Peru (Buzon et al. 2012; Conleeet al. 2009; Horn et al. 2009; Knudson et al. 2009) and in theLate Horizon Inka Empire (Andrushko et al. 2011, 2009;Turner and Armelagos 2012; Turner et al. 2009). While muchof this work has focused on archaeological human remains,isotopic research on archaeological camelid remains has alsobeen used to elucidate animal movement (Horn et al. 2009;Knudson et al. 2012a; Thornton et al. 2011).
Expected strontium isotopic signatures in the Andes
Andean bedrock geology and expected radiogenic strontiumisotope ratios
In general, the Andes Mountains are divided into theCordillera Occidental to the west and the Cordillera Orientalto the east (Figs. 1 and 2). The Cordillera Occidental is largelycomposed of late Cenozoic volcanic rocks, such as andesites(Bellido et al. 1956). Since the age of the Cenozoic volcanicrocks increases from the northern Andes to the southernAndes (see overview in Gregory-Wodzicki 2000), radiogenicstrontium isotope values are generally higher in the southernAndes (Francis et al. 1977; Harmon et al. 1984; Hawkesworthet al. 1982; Klerkx et al. 1977; McNutt et al. 1975; Rogers andHawkesworth 1989). For example, radiogenic strontium iso-tope values (87Sr/86Sr) from late Cenozoic volcanic rocks inEcuador exhibit 87Sr/86Sr=0.70431±0.00016 (1σ, n=23)(Francis et al. 1977), while exposed bedrock samples fromsimilar geologic formations in northern Chile exhibit mean87Sr/86Sr=0.70646±0.00020 (1σ, n=8) (Rogers andHawkesworth 1989). In between these extremes, lateCenozoic volcanic rocks near Arequipa in southern Peruexhibit mean 87Sr/86Sr=0.70737±0.00030 (1σ, n=16)(James 1982) and mean 87Sr/86Sr=0.70749±0.00050 (1σ,n=6) (Notsu and Lajo 1984). The Cordillera Oriental containsPaleozoic geologic formations (Bellido et al. 1956; Chepstow-Lusty et al. 2003; Gregory 1916). The Paleozoic geologicformations should be characterized by higher radiogenicstrontium isotope ratios, but their compositions have not beenmeasured in bedrock (see discussions in Andrushko et al.2011, 2009; Turner et al. 2009).
Areas that derive strontium from both the CordilleraOccidental and the Cordillera Oriental are distinct from theandesite-dominated Cordillera Occidental. For example, inthe Lake Titicaca Basin of Peru and Bolivia, igneous rocksincluding andesites and basalts are overlain by Quaternaryfluvial and lacustrine sediments from the surrounding moun-tains (Argollo et al. 1996). Although radiogenic strontiumisotope data do not yet exist for Lake Titicaca Basin bedrocksamples, sediment cores taken from Lake Titicaca exhibitmean 87Sr/86Sr=0.70838±0.00012 (1σ, n=25) (Grove et al.2003) and Lake Titicaca surface water is characterized by
Archaeol Anthropol Sci
mean 87Sr/86Sr=0.70863±0.00034 (1σ, n=3) (Coudrainet al. 2002). Farther south, the altiplano and Bolivian low-lands are characterized by much higher radiogenic strontiumisotope ratios in archaeological and modern faunal samples,although bedrock-derived data do not yet exist; for example,archaeological faunal samples from the Tiwanaku-affiliatedsite of Piñami in Cochabamba, Bolivia exhibit mean87Sr/86Sr=0.72148±0.00162 (1σ, n=4) (Lucas 2012), andsimilarly high 87Sr/86Sr values are reported for faunal sam-ples from the southern altiplano near Potosi, Bolivia(Knudson et al. 2005).
Coastal areas of Peru and Chile are dominated byQuaternary sedimentary geologic formations (Bellido et al.1956). However, we would also expect strontium from theadjacent highland areas in the Cordillera Occidental to beincorporated into the riverine and alluvial soils found on thecoasts (Bellido et al. 1956). Coastal areas may also incorpo-rate marine-derived strontium from sea spray (e.g., Whipkeyet al. 2000); strontium from sea spray or other marine sourcesexhibits the radiogenic strontium isotope value of modernsea water, which is 87Sr/86Sr=0.7092 (Veizer 1989).
Identifying sources of bioavailable strontium and baselineradiogenic strontium isotope signatures
While it is useful to generate expected radiogenic strontiumisotope values based on bedrock geology, there are a numberof advantages and disadvantages of using 87Sr/86Sr fromexposed bedrock to generate baseline radiogenic strontiumisotope signatures. As discussed above, strontium from sea
spray may contribute marine strontium to coastal areas (e.g.,Whipkey et al. 2000). More generally, not all strontium inbedrock is incorporated into soil and water, and is thereforenot necessarily incorporated into the plants and animals,including humans, in a given ecosystem (see Bentley 2006).
In addition to examining the radiogenic strontium isotopevalues in exposed bedrock, soil, plants and animal samplescan also be used to better understand 87Sr/86Sr values inbioavailable strontium. Collecting soil samples from agricul-tural fields and/or the plants themselves can target the bio-available strontium incorporated into foodstuffs. However,there are also disadvantages to using soil samples for base-line data. For example, if the soil samples are completelydissolved, rather than partially dissolved during sample prep-aration, the 87Sr/86Sr will reflect both bioavailable strontiumand strontium bound in forms that are not readily available inthe ecosystem (see discussion of strontium in environmentalsystems in Bentley 2006). In addition, the use of soil samplesfrom contemporary agricultural fields is most effective whenagricultural fields were used or likely to have been used inthe past.
The use of fertilizers can also contribute strontium to afield system, both in the past and present. Archaeologicalfield systems may have been fertilized with manure fromlocally raised animals (e.g., Bogaard et al. 2007; Finucane2007; Meharg et al. 2006), which would not have contribut-ed “non-local” strontium to the field system. In the Andes,seabird guano was used in the past and present (Julien 1985),contributing strontium with a radiogenic strontium isotoperatio indicative of seawater, which is 87Sr/86Sr=0.7092
0 100 200 300 km
0 100 200 miN
Pacific
Ocean
Lake Titicaca
Chile
PeruBolivia
Lima
Pisco
IcaPalpa
Nazca
AticoYauca
Chala
OcoñaCamaná Arequipa
Meija
Ilo
Moquegua
Tacna
Puno
Cusco
Quaternary
Cretaceous
TertiaryMesozoic-Cenozoic intrusives
Jurassic-Cretaceous
Jurassic
Carboniferous-Permian
Precambrian-DenovianPrecambrianundifferentiated
Cretaceous-Tertiaryvolcanics
Key
Fig. 1 Geologic map of the study area with sampling locations identified (based on Bellido et al. 1956)
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Rio
Colorado
Rio
Esmereldas
Rio
Dau
le
0 100 200 300 km
0 100 200 miN
RioPutum
Lake Titicaca
Argentina
PacificOcean
Ecuador
Colombia
Brazil
Bolivia
Chile
Rio
Marañó
RioYucayal
Rio Purus
Lima
Arequipa
Puno
Cusco
Quito
La Paz
Santiago
Tiwanaku
San Pedro de Atacama
Cochabamba
Lake Poopó
Late Cenozoic Volcanic RocksMean Sr Sr=0.70431±0.00016 (1 , n=23)
Late Cenozoic Volcanic RockMean Sr Sr=0.70646±0.00020 (1 , n=16)
Late Cenozoic Volcanic RockMean Sr Sr=0.70737±0.00030 (1 , n=16)
Late Cenozoic Volcanic RockMean Sr Sr=0.70749±0.00050 (1 , n=6)
Sediment CoreMean Sr Sr=0.70838±0.00012 (1 , n=25)
Surface WaterMean Sr Sr=0.70863±0.00034 (1 , n=3)Sea Water
Sr Sr=0.7092
Primarily Cenozoic to Mesozoic sedimentary rock
Primarily Paleozoic to Precambrian sedimentary rock
Primarily Precambrian igneous and metamorphic rock
Key
Primarily Cenozoic toMesozoic igneous and metamorphic rock
Fig. 2 Geologic sketch map ofthe South Central Andes withpublished mean radiogenicstrontium isotope ratios fromexposed bedrock (Francis et al.1977; Harmon et al. 1984;Hawkesworth et al. 1982; James1982; Klerkx et al. 1977;McNutt et al. 1975; Notsu andLajo 1984; Rogers andHawkesworth 1989) and LakeTiticaca Basin sediment andsurface water (Coudrain et al.2002; Grove et al. 2003)
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(Veizer 1989). In contemporary agricultural fields, the use ofimported fertilizers could also contribute “non-local” stron-tium to soil and plant samples; in a French watershed, forexample, mass-produced fertilizers contributed strontiumwitha radiogenic strontium isotope ratio of 87Sr/86Sr=0.715(Négrel and Deschamps 1996).
The addition of “non-local” strontium from fertilizers isalso an issue when using contemporary floral and faunalsamples. In addition, plants and the animals that eat themcan incorporate strontium from windborne sources, includ-ing dust (Grousset et al. 1992; Miyamoto et al. 2010; Wuet al. 2010) and sea spray (Evans et al. 2010; Whipkey et al.2000). If these sources also contributed strontium to the dietof the individuals under study, then soil, floral and faunalsamples will give a good understanding of bioavailablestrontium; for example, partially dissolved soil samples fromcoastal agricultural fields affected by sea spray, as well asfloral and faunal samples from the same area, could give anexcellent picture of bioavailable strontium in the region,including marine-derived strontium from sea spray. In con-trast, using a contemporary field system that has been treatedwith mass-produced artificial fertilizers not available in thepast would not provide a reasonable estimate of bioavailablestrontium for a population from that area.
A number of scholars have discussed the potential of faunalremains, particularly archaeological and/or modern enamelsamples from small mammals, for establishing baseline87Sr/86Sr signatures in a given region (Bentley 2006; Evansand Tatham 2004; Price et al. 2002). Like floral samples, faunalremains provide a good estimate of the bioavailable strontiumin a given ecosystem. However, the range over which an animalincorporates strontium from food and water sources will varybased on the species (e.g., Britton et al. 2011; Frei et al. 2009a;Hedman et al. 2009; Knudson et al. 2012a; Price et al. 2008;Shaw et al. 2009; Sykes et al. 2011, 2006; Thornton 2011;Thornton et al. 2011; Viner et al. 2010). The range for smallmammals provides data on 87Sr/86Sr values from a larger areathan that of floral samples, yet is relatively small compared to alarge geologic zone. Larger animals, such as llamas (Lamaglama), may incorporate strontium from a large area, makingit harder to trace the 87Sr/86Sr values to specific geologic zones(Knudson et al. 2012a; Thornton et al. 2011). When usingarchaeological remains, tooth enamel samples are more resis-tant to diagenetic contamination and are preferred (Bentley2006; Evans and Tatham 2004; Price et al. 2002).
We note that an essential aspect of using radiogenic stron-tium isotope analysis to infer human paleomobility is deter-mining the actual strontium sources in an individual’s diet. Ifthe dietary strontium derives from sources that wereimported or traded widely, radiogenic strontium isotopeanalysis would identify trade and exchange of foodstuffsrather than human residential mobility. In the Andes, manywidely traded plant products, like maize (Z. mays), or
animals that may have traveled over a wide range of geologiczones, like llamas (L. glama), are not generally high instrontium (e.g., Knudson et al. 2009; Tung and Knudson2008). However, understanding the 87Sr/86Sr values in bio-available strontium as well as the source of dietary strontiumis an important aspect of paleomobility studies using radio-genic strontium isotopes.
Materials
Soils from agricultural fields can provide a way to under-stand the bioavailable strontium incorporated by cultivatedplant products. This is particularly important given the rela-tively high strontium concentrations in many plant products(Runia 1987), which likely provide the majority of strontiumconsumed in many populations. In contrast, soil or geologicsamples from mortuary contexts or areas (e.g., bedrock out-crops) not extensively used in the past may not have contrib-uted much or any strontium to the diet, and therefore may notprovide a reasonable estimation of the bioavailable strontiumand its radiogenic strontium isotope ratios.
Soil samples were collected from modern agricultural fieldsin southern Peru between 2007 and 2009 (Table 1, Fig. 1).Given the lack of productive agricultural land in many parts ofthe Andes, it is possible that prehistoric populations used theselocations as well; indeed, many parts of the Andes have a longhistory of agricultural land use in the same field systems (seediscussions in Bandy 2005; Craig et al. 2011; Erickson 1988;Graffam 1992; Janusek and Kolata 2004; Wernke 2007, 2010).When possible, soil samples were collected from field systemsthat were being traditionally farmed with little or no importedfertilizers and were being used for crops grown in the Andeanpast, such as maize (Z. mays), yuca (Manihot esculenta), pota-toes (Solanum tuberosum), and oca (Oxalis tuberosa) (Table 1).However, particularly on the coast of Peru, many currentagricultural products were introduced after the arrival of theSpanish in AD 1532. We also included soil samples fromagricultural fields that were fallow at the time of sampling. Ineach study area, approximately 25–30 g of surface soil wascollected from the top 10 cm of soil since this interval generallycontains the highest concentrations of exchangeable cations(Blum et al. 2000; Johnson et al. 1991). Sampling locales werechosen to investigate both inter- and intra-regional variability inradiogenic strontium isotope ratios.
Methods
All soil samples were prepared under the direction ofKnudson at Arizona State University in the ArchaeologicalChemistry Laboratory using published methods (Blum et al.2000). A representative soil sample was weighed and dried
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Table 1 87Sr/86Sr values for soil samples from modern agricultural fields in Peru
Site Laboratory number Specimen number Agricultural crop cultivated 87Sr/86Sr
Arequipa ACL-2193 AQP-AIS916 Solanum tuberosum 0.70768
Arequipa ACL-2194 AQP-AIS917 Zea mays 0.70789
Arequipa ACL-2195 AQP-AIS918 Allium cepa 0.70563
Arequipa ACL-2196 AQP-AIS921 Apium gravolens dulce 0.70849
Arequipa ACL-2197 AQP-AIS925 Medicago sativa 0.70801
Arequipa ACL-2198 AQP-AIS926 Zea mays 0.70798
Arequipa ACL-2199 AQP-AIS931 Zea mays 0.70934
Arequipa ACL-2200 AQP-AIS933 Medicago sativa 0.70846
Atico ACL-2256 ATICO-AIS844 Zea mays 0.70637
Atico ACL-2257 ATICO-AIS846 Olea europaea 0.70689
Atico ACL-2259 ATICO-AIS860 Olea europaea 0.70746
Atico ACL-2260 ATICO-AIS862 Olea europaea 0.70849
Camaná ACL-2236 CAMA-AIS876 Oryza sp. 0.70842
Camaná ACL-2237 CAMA-AIS878 Oryza sp. 0.70841
Camaná ACL-2238 CAMA-AIS880 Oryza sp. 0.70836
Camaná ACL-2239 CAMA-AIS882 Oryza sp. 0.70968
Chala ACL-2251 CHALA-AIS852 Ficus carica 0.70759
Chala ACL-2252 CHALA-AIS853 Malus domestica 0.70796
Chala ACL-2253 CHALA-AIS855 Citrullus lanatus 0.70724
Cusco ACL-2221 CUSCO-AIS879 Solanum tuberosum 0.70889
Cusco ACL-2222 CUSCO-AIS970 Fallow (native grasses) 0.70771
Cusco ACL-2223 CUSCO-AIS971 Fallow (native grasses) 0.70775
Cusco ACL-2224 CUSCO-AIS973 Fallow (native grasses) 0.70849
Cusco ACL-2225 CUSCO-AIS976 Fallow (native grasses) 0.70799
Cusco ACL-2226 CUSCO-AIS977 Fallow (native grasses) 0.70786
Cusco ACL-2227 CUSCO-AIS980 Fallow (native grasses) 0.70939
Cusco ACL-2228 CUSCO-AIS982 Solanum tuberosum 0.70850
Cusco ACL-2229 CUSCO-AIS984 Fallow (native grasses) 0.71335
Cusco ACL-2230 CUSCO-AIS988 Zea mays 0.71894
Cusco ACL-2231 CUSCO-AIS994 Phaseolus vulgaris 0.70853
Cusco ACL-2232 CUSCO-AIS998 Fallow (native grasses) 0.70932
Cusco ACL-2233 CUSCO-AIS999 Fallow (native grasses) 0.70912
Cusco ACL-2234 CUSCO-AIS1004 Zea mays 0.70988
Cusco ACL-2235 CUSCO-AIS1006 Fallow (native grasses) 0.71036
Ica ACL-2268 ICA-AIS780 Vitis sp. 0.70695
Ica ACL-2269 ICA-AIS782 Vitis sp. 0.70711
Ica ACL-2270 ICA-AIS784 Vitis sp. 0.70761
Ica ACL-2271 ICA-AIS786 Mangifera indica 0.70715
Ilo ACL-2192 ILO-AIS898 Passiflora edulis 0.70679
Ilo ACL-2245 ILO-AIS884 Oryza sp. 0.70870
Lima ACL-2178 LIMA-AIS724 Zea mays 0.70738
Lima ACL-2179 LIMA-AIS726 Zea mays 0.70736
Lima ACL-2180 LIMA-AIS728 Zea mays 0.70654
Lima ACL-2181 LIMA-AIS730 Phaseolus vulgaris 0.70746
Lima ACL-2182 LIMA-AIS733 Zea mays 0.70772
Lima ACL-2183 LIMA-AIS735 Zea mays 0.70758
Lima ACL-2184 LIMA-AIS737 Manihot esculenta 0.70745
Lima ACL-2185 LIMA-AIS739 Fallow (native grasses) 0.70691
Lima ACL-2186 LIMA-AIS743 Gossypium barbadense 0.70733
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Table 1 (continued)
Site Laboratory number Specimen number Agricultural crop cultivated 87Sr/86Sr
Lima ACL-2187 LIMA-AIS745 Asparagus officinalis 0.70678
Lima ACL-2188 LIMA-AIS746 Gossypium barbadense 0.70729
Lima ACL-2189 LIMA-AIS748 Gossypium barbadense 0.70704
Mejía ACL-2246 MEJIA-AIS886 Zea mays 0.70808
Mejía ACL-2247 MEJIA-AIS889 Oryza sp. 0.70804
Mejía ACL-2248 MEJIA-AIS891 Oryza sp. 0.70798
Mejía ACL-2249 MEJIA-AIS893 Saccharum sp. 0.70801
Mejía ACL-2250 MEJIA-AIS895 Oryza sp. 0.70799
Moquegua ACL-2190 MOQ-AIS899 Vitis sp. 0.70202
Moquegua ACL-2191 MOQ-AIS901 Persea americana 0.70513
Nazca ACL-2262 NAZCA-AIS825 Vitis sp. 0.70611
Nazca ACL-2263 NAZCA-AIS828 Gossypium barbadense 0.70565
Nazca ACL-2264 NAZCA-AIS832 Gossypium barbadense 0.70673
Nazca ACL-2267 NAZCA-AIS837 Zea mays 0.70659
Nazca ACL-2261 NAZCA-AIS818 Gossypium barbadense 0.70598
Ocoña ACL-2240 OCONA-AIS864 Oryza sp. 0.70760
Ocoña ACL-2241 OCONA-AIS866 Oryza sp. 0.70739
Ocoña ACL-2242 OCONA-AIS869 Oryza sp. 0.70765
Ocoña ACL-2243 OCONA-AIS871 Oryza sp. 0.70653
Ocoña ACL-2244 OCONA-AIS874 Oryza sp. 0.70857
Palpa ACL-2272 PALPA-AIS789 Zea mays 0.70668
Palpa ACL-2273 PALPA-AIS790 Gossypium barbadense 0.70760
Palpa ACL-2274 PALPA-AIS792 Vitis sp. 0.70805
Palpa ACL-2275 PALPA-AIS794 Gossypium barbadense 0.70680
Palpa ACL-2276 PALPA-AIS797 Gossypium barbadense 0.70656
Palpa ACL-2277 PALPA-AIS799 Gossypium barbadense 0.70723
Palpa ACL-2278 PALPA-AIS802 Gossypium barbadense 0.70659
Palpa ACL-2279 PALPA-AIS804 Gossypium barbadense 0.70670
Palpa ACL-2280 PALPA-AIS805 Gossypium barbadense 0.70649
Palpa ACL-2281 PALPA-AIS807 Zea mays 0.70671
Palpa ACL-2282 PALPA-AIS809 Zea mays 0.70728
Palpa ACL-2283 PALPA-AIS812 Unknown (likely Zea mays) 0.70646
Palpa ACL-2284 PALPA-AIS814 Medicago sativa 0.70680
Palpa ACL-2285 PALPA-AIS816 Mangifera indica 0.70700
Pisco ACL-2286 PISCO-AIS750 Gossypium barbadense 0.70867
Pisco ACL-2287 PISCO-AIS752 Gossypium barbadense 0.70757
Pisco ACL-2288 PISCO-AIS754 Zea mays 0.70764
Pisco ACL-2289 PISCO-AIS756 Gossypium barbadense 0.70790
Pisco ACL-2290 PISCO-AIS758 Gossypium barbadense 0.70768
Pisco ACL-2291 PISCO-AIS760 Mangifera indica 0.70752
Pisco ACL-2292 PISCO-AIS762 Gossypium barbadense 0.70743
Pisco ACL-2293 PISCO-AIS764 Gossypium barbadense 0.70765
Pisco ACL-2294 PISCO-AIS766 Manihot esculenta 0.70801
Pisco ACL-2295 PISCO-AIS768 Zea mays 0.70748
Pisco ACL-2296 PISCO-AIS770 Zea mays 0.70729
Pisco ACL-2297 PISCO-AIS772 Gossypium barbadense 0.70742
Pisco ACL-2298 PISCO-AIS774 Zea mays 0.70706
Pisco ACL-2300 PISCO-AIS778 Medicago sativa 0.70704
Puno ACL-2201 PUNO-AIS937 Solanum tuberosum, Oxalis tuberosa 0.70921
Archaeol Anthropol Sci
for 48 h at 120 °C before preparation. The dried soil samplewas then crushed with a Coors porcelain mortar and pestleand then ashed for approximately 10 h at 800 °C. The soilsample was then partially dissolved in 10 mL of 1 M ammo-nium acetate (CH3COONH4, or NH4OAc) at room temper-ature for 24 h and then decanted. A partial dissolution meth-od was used to approximate the bioavailable strontium in thesoil samples. The partial dissolution method is designed tomaximize release of bioavailable strontium and minimizerelease of strontium that is generally not bioavailable and isinstead tightly bound in the mineral crystal lattices in the soil(Blum et al. 2000).
All samples were analyzed at the W.M. Keck FoundationLaboratory for Environmental Biogeochemistry at Arizona StateUniversity. First, strontium was separated from the sample ma-trix using EiChrom SrSpec resin (50–100 μm in diameter) andultrapure 5 M nitric acid (HNO3) following established pro-cedures (e.g., Knudson and Price 2007). Radiogenic and stablestrontium isotopes were measured on a Neptune multi-collectorinductively coupled plasmamass spectrometer, where SRM-987exhibited 87Sr/86Sr=0.710265±0.000010 (2σ, n=25), followingpublished values of 87Sr/86Sr=0.710263±0.000016 (2σ) inanalyses of international standard SRM-987 (Stein et al. 1997).
Results
The results for the modern soil samples show a wide range inradiogenic strontium isotope ratios, from 87Sr/86Sr=0.70202to 87Sr/86Sr=0.71894 (Table 1, Fig. 3). The mean for all soilsamples is 87Sr/86Sr=0.70773±0.00166 (1σ, n=114). Mean
87Sr/86Sr values for each region included in the study arelisted in Table 2.
Discussion
Comparison of radiogenic strontium isotope ratios in soiland bedrock samples
We first compare the measured 87Sr/86Sr values of soil sam-ples collected from modern agricultural fields with the ob-served 87Sr/86Sr values from bedrock samples (Tables 2 and3). The majority of radiogenic strontium isotope analyses onAndean bedrock samples are from late Cenozoic volcanicrocks. In this study, one sampling location was dominatedby late Cenozoic volcanic rocks; in Arequipa, Peru mean87Sr/86Sr=0.70797±0.00115 (1σ, n=8) (Tables 2 and 3).Andesite samples collected near Arequipa, Peru exhibit mean87Sr/86Sr=0.70737±0.00030 (1σ, n=16) (James 1982) andmean 87Sr/86Sr=0.70749±0.00050 (1σ, n=6) (Notsu andLajo 1984).
While no results from bedrock samples currently exist forthe Lake Titicaca Basin, sediment cores taken from LakeTiticaca exhibit mean 87Sr/86Sr=0.70838±0.00012 (1σ,n=25) (Grove et al. 2003). In addition, Lake Titicaca surfacewater exhibits mean 87Sr/86Sr=0.70863±0.00034 (1σ, n=3)(Coudrain et al. 2002). Our soil data from Puno, Peru in theLake Titicaca Basin exhibit mean 87Sr/86Sr=0.70835±0.00135(1σ, n=11) (Table 2).
The only other sampling location with published geologicdata is Cusco, Peru, where one andesite sample exhibits
Table 1 (continued)
Site Laboratory number Specimen number Agricultural crop cultivated 87Sr/86Sr
Puno ACL-2202 PUNO-AIS940 Triticum sp. 0.70812
Puno ACL-2203 PUNO-AIS942 Solanum tuberosum 0.70867
Puno ACL-2204 PUNO-AIS946 Solanum tuberosum, Chenopodium quinoa 0.70696
Puno ACL-2205 PUNO-AIS957 Solanum tuberosum, Chenopodium quinoa 0.70783
Puno ACL-2206 PUNO-AIS952 Solanum tuberosum 0.70743
Puno ACL-2207 PUNO-AIS954 Solanum tuberosum, 0.71191
Puno ACL-2208 PUNO-AIS957 Solanum tuberosum, Chenopodium quinoa 0.70842
Puno ACL-2209 PUNO-AIS960 Solanum tuberosum, Oxalis tuberosa 0.70787
Puno ACL-2210 PUNO-AIS965 Fallow (native grasses) 0.70790
Puno ACL-2211 PUNO-AIS966 Fallow (native grasses) 0.70837
Tacna ACL-2212 TACNA-AIS904 Fallow (native grasses) 0.70884
Tacna ACL-2213 TACNA-AIS909 Zea mays 0.70746
Tacna ACL-2214 TACNA-AIS911 Vitis sp. 0.70761
Tacna ACL-2215 TACNA-AIS913 Zea mays 0.70663
Yauca ACL-2254 YAUCA-AIS848 Olea europaea 0.70482
Yauca ACL-2255 YAUCA-AIS850 Olea europaea 0.70613
Archaeol Anthropol Sci
87Sr/86Sr=0.70670 (Notsu and Lajo 1984). Soil samplescollected from modern agricultural fields near Cusco, Peruexhibit mean 87Sr/86Sr=0.70980±0.00301 (1σ, n=15)(Tables 2 and 3). The difference in radiogenic strontium
isotope values from different sources in the Cusco regionwill be further explored below using faunal data.
Therefore, in Arequipa, Peru, and Puno, Peru, the mea-sured 87Sr/86Sr values of soil samples collected from modernagricultural fields reflect the expected 87Sr/86Sr values basedon bedrock geology. In these cases, both the published87Sr/86Sr values from exposed bedrock, lake cores andground water and 87Sr/86Sr values from soil samples providean accurate measure of baseline radiogenic strontium isotopesignatures in these regions.
However, there are many parts of the Andes, particularlyon the coast, where published bedrock 87Sr/86Sr values are notavailable. In addition, while the coastal Andean valleys aredominated by Quaternary sedimentary geologic formations(Bellido et al. 1956), riverine and alluvial soils and water inthese regions would incorporate both strontium from theadjacent highlights, composed largely of late Cenozoic volca-nic rock (Bellido et al. 1956), and likely from the PacificOcean (e.g., Whipkey et al. 2000). Soil samples from agricul-tural fields within the same drainage system on the coast arevery similar, as expected. For example, Nazca, Peru andPalpa, Peru are both located within the Nazca Drainage. InNazca, Peru, mean 87Sr/86Sr=0.70624±0.00051 (1σ, n=5),while in Palpa, Peru, mean 87Sr/86Sr=0.70694±0.00048 (1σ,n=14; Table 2). Similarly, soil samples from other sites on thesouthern Peruvian coast, including Atico, Chala, Ica, Ocoña,Pisco, and Tacna, all exhibit similar mean 87Sr/86Sr values.Hence, broad population movements or migration among
0 100 200 300 km
0 100 200 miN
Peru
Pacific
Ocean
Bolivia
Chile
Lake Titicaca
LimaMean Sr/ Sr=0.70722±0.00036 (1 , n=12)Minimum Sr/ Sr= 0.70654Maximum Sr/ Sr= 0.70772
PiscoMean Sr/ Sr: 0.70751±0.00028(1 , n=14)Minimum Sr/ Sr= 0.70704Maximum Sr/ Sr= 0.70801
PalpaMean Sr/ Sr: 0.70694±0.00048 (1 , n=14)Minimum Sr/ Sr= 0.70646Maximum Sr/ Sr= 0.70805
AticoMean Sr/ Sr: 0.70761±0.00081 (1 , n=4)Minimum Sr/ Sr= 0.70689Maximum Sr/ Sr= 0.70849
Yaucan=2Minimum Sr/ Sr= 0.70482Maximum Sr/ Sr=0.70613
CamanáMean Sr/ Sr: 0.70882±0.00075 (1 , n=4)Minimum Sr/ Sr= 0.70836Maximum Sr/ Sr= 0.70968
MeijaMean Sr/ Sr: 0.70801±0.00003 (1 , n=5)Minimum Sr/ Sr= 0.70798Maximum Sr/ Sr= 0.70804 Ilo
n=2Minimum Sr/ Sr= 0.70679Maximum Sr/ Sr= 0.70870
TacnaMean Sr/ Sr: 0.70723±0.00053 (1 , n=4)Minimum Sr/ Sr= 0.70663Maximum Sr/ Sr= 0.70761
Moqueguan=2Minimum Sr/ Sr= 0.70202Maximum Sr/ Sr= 0.70513
PunoMean Sr/ Sr: 0.70835±0.00135 (1 , n=11)Minimum Sr/ Sr= 0.70696Maximum Sr/ Sr= 0.71191
ArequipaMean Sr/ Sr: 0.70797±0.00115 (1 , n=8)Minimum Sr/ Sr= 0.70563Maximum Sr/ Sr= 0.70934
OcoñaMean Sr/ Sr: 0.70754±0.00084 (1 , n=5)Minimum Sr/ Sr= 0.70653Maximum Sr/ Sr= 0.70857
ChalaMean Sr/ Sr: 0.70760±0.00051 (1 , n=3)Minimum Sr/ Sr= 0.70724Maximum Sr/ Sr= 0.70796
NazcaMean Sr/ Sr: 0.70624±0.00051 (1 , n=5)Minimum Sr/ Sr= 0.70565Maximum Sr/ Sr= 0.70673
IcaMean Sr/ Sr: 0.70729±0.00028 (1 , n=4)Minimum Sr/ Sr= 0.70711Maximum Sr/ Sr= 0.70761 Cusco
Mean Sr/ Sr: 0.709080±0.00301 (1 , n=15)Minimum Sr/ Sr= 0.70771Maximum Sr/ Sr= 0.71894
Fig. 3 Map of the study area with sampling locations and mean radiogenic strontium isotope ratios for modern soil samples collected from eachlocation
Table 2 Descriptive statistics for the 87Sr/86Sr values of soil samplesfrom Peru
Site Mean87Sr/86Sr
Standarddeviation
Number Minimum87Sr/86Sr
Maximum87Sr/86Sr
Arequipa 0.70797 0.00115 8 0.70563 0.70934
Atico 0.70761 0.00081 4 0.70689 0.70849
Camaná 0.70882 0.00075 4 0.70836 0.70968
Chala 0.70760 0.00051 3 0.70724 0.70796
Cusco 0.70980 0.00301 15 0.70771 0.71894
Ica 0.70729 0.00028 4 0.70711 0.70761
Ilo NA NA 2 0.70679 0.70870
Lima 0.70722 0.00036 12 0.70654 0.70772
Mejía 0.70801 0.00003 5 0.70798 0.70804
Moquegua NA NA 2 0.70202 0.70513
Nazca 0.70624 0.00051 5 0.70565 0.70673
Ocoña 0.70754 0.00084 5 0.70653 0.70857
Palpa 0.70694 0.00048 14 0.70646 0.70805
Pisco 0.70751 0.00028 14 0.70704 0.70801
Puno 0.70835 0.00135 11 0.70696 0.71191
Tacna 0.70723 0.00053 4 0.70663 0.70761
Yauca NA NA 2 0.70482 0.70613
Archaeol Anthropol Sci
different drainages on the southern Peruvian coast would bedifficult to identify using radiogenic strontium isotope analy-sis alone.
Comparison of baseline radiogenic strontium isotope ratiosfrom bedrock, soil, faunal, and floral samples
Given the various advantages and disadvantages of using dif-ferent sample types to generate baseline radiogenic strontiumisotope ratios (see Table 1 in Evans and Tatham 2004), it isbeneficial to utilize multiple lines of evidence. Combining datafrom soil, water, fauna, and flora gives a reasonable sense of thespatial variation in 87Sr/86Sr values within and between specificgeologic zones (Blum et al. 2000; Evans and Tatham 2004;Hodell et al. 2004). For example, in Mesoamerica and CentralAmerica, there was general agreement among 87Sr/86Srvalues for soil, water, and floral samples within specificgeologic zones, although variability based on strontiumsources in each sample type and the relative strontiumcontributions of each source is also present (Hodell et al.2004). Similarly, in the UK, there is general agreement be-tween bedrock geology and samples from water and plants,though the authors note that marine-derived strontium fromsea spray and rainwater also contribute to bioavailable stron-tium, particularly in western regions (Evans et al. 2010).
With the advantages and disadvantages of different base-line sample types in mind, we turn to a comparison of asubset of 87Sr/86Sr values from contemporary soil sampleswith published 87Sr/86Sr values for both bedrock and faunalsamples from the same Andean regions. As with the previ-ously discussed bedrock data, faunal data do not yet exist forall of the regions included in our soil analyses. However,where both soil and faunal data exist, the two sample typesgenerally have similar 87Sr/86Sr values (Table 3). For exam-ple, as previously discussed, radiogenic strontium isotopedata from agricultural soils and andesite samples fromArequipa, Peru are in very close agreement. In the LakeTiticaca Basin of Peru and Bolivia, faunal bone samplesexhibit mean 87Sr/86Sr=0.70963±0.00028 (1σ, n=8) in theTiwanaku Valley and mean 87Sr/86Sr=0.70888±0.000719(1σ, n=5) in the Desaguadero Valley (Knudson andPrice 2007; Knudson and Torres-Rouff 2009). In com-parison, sediment cores taken from Lake Titicaca exhibitmean 87Sr/86Sr=0.70838±0.00012 (1σ, n=25) (Groveet al. 2003) and soil data from Puno, Peru exhibit mean87Sr/86Sr=0.70835±0.00135 (1σ, n=11).
In the Majes Valley of southern Peru, soil from agriculturalfields near the coastal town of Camaná, Peru exhibit mean87Sr/86Sr=0.70882±0.00075 (1σ, n=4). These data are verysimilar to modern and archaeological faunal data from Beringaand Aplao, located approximately 60 km inland from Camaná,Peru. At the archaeological site of Beringa, faunal bone sam-ples exhibited mean 87Sr/86Sr=0.70836±0.00027 (1σ, n=6),
while modern faunal bone samples from the nearby town ofAplao, Peru exhibited mean 87Sr/86Sr=0.70860±0.00001 (1σ,n=5; Knudson and Tung 2011).
Like the Majes Valley, the Nazca Drainage does not havepublished radiogenic strontium isotope data for bedrock.However, soil and faunal samples from various sites in theNazca Drainage are in close agreement. Soil from modernagricultural fields near the town of Nazca, Peru exhibit mean87Sr/86Sr=0.70624±0.00051 (1σ, n=5), and samples col-lected near the town of Palpa, Peru exhibit mean87Sr/86Sr=0.70694±0.00048 (1σ, n=14). Similarly, modernrodent bone samples from the Middle Nazca Valley exhibitmean 87Sr/86Sr=0.70642±0.00053 (1σ, n=3) and archaeo-logical faunal bone samples from the site of La Tiza exhibitmean 87Sr/86Sr=0.70646±0.00041 (1σ, n=3; Conlee et al.2009), while faunal enamel samples from the Ica, Palpa, andNazca Valleys in the Nazca Drainage exhibit mean87Sr/86Sr=0.70669±0.00026 (1σ, n=14; Horn et al. 2009).Samples from a higher-altitude sampling location in theNazca Drainage had slightly lower radiogenic strontiumisotope values than the samples collected from lower alti-tudes; in the Upper Tierras Blancas Valley, modern faunalbone samples exhibit mean 87Sr/86Sr=0.70587±0.00008(1σ, n=7).
However, some regions exhibited strontium isotopic vari-ability in bedrock, soil, and faunal samples. The largest rangeoccurs in the Cusco region, where one andesite sample ex-hibits 87Sr/86Sr=0.70670 (Notsu and Lajo 1984) and archae-ological enamel samples from Machu Picchu, Peru exhibitmean 87Sr/86Sr=0.71407±0.00014 (1σ, n=3; Turner et al.2009). Between these two extremes, soil from modern agri-cultural fields exhibits mean 87Sr/86Sr=0.70980±0.00301(1σ, n=15). In addition, modern faunal enamel samples fromtwo archaeological sites in the Cusco Valley exhibit mean87Sr/86Sr = 0.70826 ± 0.00027 (1σ , n= 4) and mean87Sr/86Sr=0.70795±0.00013 (1σ, n=4; Andrushko et al.2009). Although faunal samples from Machu Picchu are dis-tinct from other soil and faunal data from the Cusco area(Table 3), Turner et al. (2009) rightfully note that the faunaldata fromMachu Picchu reflect the differences in the bedrockgeology within the region. Similarly, while the andesite pro-vides an accurate reflection of the radiogenic strontium iso-tope values found in late Cenozoic volcanic rocks in theregion, relying solely on 87Sr/86Sr values found in one typeof bedrock in the region would not accurately reflect the inputsfrom different geologic formations found in the Cusco Valley.Therefore, the variability in baseline 87Sr/86Sr values fromCusco, Peru reflects variability in bedrock geology. In thiscase, as in other geologically complex areas, it would be idealto generate baseline data from soil and faunal samples, ratherthan relying on isolated bedrock samples.
Similarly, in the Osmore Drainage of southern Peru, therelatively large range in 87Sr/86Sr values from modern soil
Archaeol Anthropol Sci
Table 3 Descriptive statistics for 87Sr/86Sr values from Peruvian bedrock, soil, and faunal samples
Site, country Sample type Mean 87Sr/86Sra Standard deviation(1σ)
Number Source
Arequipa, Peru
Arequipa, Peru Andesite 0.70737 0.00030 16 James 1982
Arequipa, Peru Andesite 0.70749 0.00050 6 Notsu and Lajo 1984
Arequipa, Peru Soil (modern) 0.70797 0.00115 8 This manuscript
Central Coast, Peru
Lima, Peru Soil (modern) 0.70722 0.00036 12 This manuscript
Ancón, Peru Soil (modern)b 0.70786 b,0.70761 b
NA 2 Slovak et al. 2009
Ancón, Peru Rodent bone (modern andarchaeological)
0.70654 0.00012 5 Slovak et al. 2009
Pachacamac, Peru Rodent bone (modern) 0.70684 0.00016 9 This manuscript
Cusco, Peru
Cusco, Peru Andesite 0.70670 NA 1 Notsu and Lajo 1984
Cusco, Peru Soil (modern) 0.70980 0.00301 15 This manuscript
Tipón, Peru Rodent enamel (modern) 0.70826 0.00027 4 Andrushko et al. 2009
Choquepukio, Peru Rodent enamel (modern) 0.70795 0.00013 4 Andrushko et al. 2009
Machu Picchu, Peru Rodent enamel (archaeological) 0.71407 0.0014 3 Turner et al. 2009
Lake Titicaca Basin, Peru and Bolivia
Lake Titicaca, Bolivia andPeru
Sediment cores (modern) 0.70838 0.00012 25 Grove et al. 2003
Puno, Peru Soil (modern) 0.70835 0.00135 11 This manuscript
Tiwanaku Valley, Bolivia Rodent bone (modern) 0.70963 0.00028 8 Knudson and Price 2007
Desaguadero Valley, Bolivia Rodent bone (archaeological) 0.70888 0.00019 5 Knudson and Torres-Rouff2009
Majes Valley, Peru
Camaná, Peru Soil (modern) 0.70882 0.00075 4 This manuscript
Beringa, Peru Rodent, dog bone (archaeological) 0.70836 0.00027 6 Knudson and Tung 2011
Aplao, Peru Rodent bone (modern) 0.70860 0.00001 5 Knudson and Tung 2011
Nazca Drainage, Peru
Nazca, Peru Soil (modern) 0.70624 0.00051 5 This manuscript
Palpa, Peru Soil (modern) 0.70694 0.00048 14 This manuscript
La Tiza, Peru Rodent bone (archaeological) 0.70646 0.00041 7 Conlee et al. 2009
Middle Nazca Valley, Peru Rodent bone (modern) 0.70642 0.00053 3 Conlee et al. 2009
Upper Tierras BlancasValley, Peru
Rodent bone (modern) 0.70587 0.00008 7 Conlee et al. 2009
Ica, Palpa, and NazcaValleys, Peru
Faunal enamel (archaeological) 0.70669 0.00026 14 Horn et al. 2009
Osmore Drainage, Peru
Ilo, Peru Soil (modern) 0.70679,0.70870
NA 2 This manuscript
Moquegua, Peru Soil (modern) 0.70202,0.70513
NA 2 This manuscript
Ilo, Peru Rodent bone (modern) 0.70671,0.70668
NA 2 Knudson and Price 2007
Chiribaya Baja, Peru Rodent bone (archaeological) 0.70789,0.70672
NA 2 Knudson and Price 2007
Moquegua, Peru Rodent bone (modern) 0.70625 0.00018 3 Knudson et al. 2004
aWhen less than three data points were available, the actual 87 Sr/86 Sr values are listed rather than mean 87 Sr/86 Sr valuesbModern soils from mortuary contexts at the archaeological site of Ancón, Peru were prepared using similar methods as the soil samples in this study(Slovak et al. 2009). Data reported are for the ammonium acetate extractable fraction of soil (Slovak et al. 2009)
Archaeol Anthropol Sci
samples from Ilo and Moquegua, Peru is reflected in therange of 87Sr/86Sr values of archaeological and modern fau-nal samples, particularly from Ilo (Table 3; Knudson andBuikstra 2007; Knudson and Price 2007). This likely reflectsmixing of strontium from different sources in this geologi-cally heterogeneous area (Knudson and Buikstra 2007).
Finally, on the central coast of Peru, there is a smalldifference between radiogenic strontium isotope valuesin soil and fauna samples (Table 3). Soil samples frommodern agricultural fields near Lima, Peru exhibit mean87Sr/86Sr=0.70722±0.00036 (1σ, n=12). Similarly, soilsfrom the archaeological site of Ancón, Peru exhibit87Sr/86Sr=0.70786 and 87Sr/86Sr=0.70761 (Slovak et al.2009). However, archaeological and modern faunal samplesfrom Ancón, Peru exhibit mean 87Sr/86Sr=0.70654±0.00012(1σ, n=5; Slovak et al. 2009), while modern faunal samplesfrom Pachacamac, Peru exhibit mean 87Sr/86Sr =0.70684±0.00016 (1σ, n=9; Table 3). This offset and,more particularly, bioavailable strontium isotope values onthe Central Coast of Peru are currently being investigated.
Conclusion
We measured radiogenic strontium isotope ratios for soil sam-ples frommodern agricultural fields from the following areas incentral and southern Peru: Arequipa, Atico, Camaná, Chala,Cusco, Ica, Ilo, Lima, Mejía, Moquegua, Nazca, Ocoña, Palpa,Pisco, Puno, Tacna, and Yauca. In general, radiogenic stron-tium isotope ratios from soil samples reflect the observed87Sr/86Sr values in bedrock sources, and are in agreement withthe isotopic composition of bioavailable strontium determinedusing faunal samples. The large dataset of 87Sr/86Sr values forsoil samples also helps to point out the regions that can, andcannot, be distinguished in the Andes using this method. Forexample, soil samples from sites on the southern Peruviancoast, including Atico, Chala, Ica, Nazca, Ocoña, Palpa,Pisco, and Tacna, exhibit similar mean 87Sr/86Sr values.Therefore, radiogenic strontium isotope analysis alone wouldnot easily distinguish population movement between differentdrainages on the southern Peruvian coast, although movementsbetween the coast and highlands could be more easily identi-fied. For study sites on, for example, the southern coast of Peru,multiple lines of evidence would be necessary to “geo-locate”an individual to a specific valley. Rather than “geo-locating”individuals who lived in the past, we look forward to futurestudies that instead “geo-restrict” individuals, incorporatingsophisticated understandings of the variability of bioavailablestrontium in the study area, diet, and larger region.
Acknowledgments This project would not have been possible with-out generous funding to White, Knudson, and Longstaffe from theSocial Science and Humanities Research Council of Canada and with
grants to Knudson from the Institute for Social Science Research atArizona State University and the School of Human Evolution andSocial Change at Arizona State University. We are grateful to Dr.Jean-Francois Millaire of The University of Western Ontario and Lic.Estaurdo La Torre for sample collection in the field. In the Archaeolog-ical Chemistry Laboratory at Arizona State University, we are gratefulfor the laboratory assistance of Allisen Dahlstedt and AlejandraGonzalez and the mapmaking expertise of Elise Alonzi. We also thankDrs. Ariel Anbar and Gwyneth Gordon of the W.M. Keck Foundationfor Environmental Biogeochemistry for laboratory access and expertise.Finally, the first author would like to thank a number of scholars forfruitful discussions about isotopic research in the Andes, particularlyDrs. Corina Kellner and Bethany Turner.
References
Andrushko VA, Buzon MR, Simonetti A, Creaser RA (2009) Strontiumisotope evidence for prehistoric migration at Chokepukio, Valleyof Cuzco, Peru. Lat Amer Antiq 20(1):57–75
Andrushko VA, Buzon MR, Gibaja AM, McEwan GF, Simonetti A,Creaser RA (2011) Investigating a child sacrifice event from theInca heartland. J Archaeolo Sci 38(2):323–333. doi:10.1016/j.jas.2010.09.009
Argollo J, Ticcla L, Kolata AL, Rivera O (1996) Geology, geomorphol-ogy, and soils of the Tiwanaku and Catari River Basins. In: KolataAL (ed) Tiwanaku and its hinterland: archaeology and paleoecol-ogy of an Andean civilization, 1st edn. Smithsonian InstitutionPress, Washington, D.C, pp 57–88
Bandy MS (2005) Energetic efficiency and political expediency inTiticaca Basin raised field agriculture. J Anthropol Archaeol24(3):271–296
Bellido E, Navarez S, Simons FS (1956) Mapa geológico del Perú. LaSociedad Geológica del Perú, Lima
Bendrey R, Hayes TE, Palmer MR (2009) Patterns of Iron Age horsesupply: an analysis of strontium isotope ratios in teeth. Archaeometry51(1):140–150
Benson LV (2010)Who provided maize to Chaco Canyon after the mid-12th-century drought? J Archaeol Sci 37(3):621–629
Benson L, Cordell L, Vincent K, Taylor H, Stein J, Farmer GL, Futa K(2003) Ancient maize from Chacoan great houses: where was itgrown? Proc Natl Acad Sci 100:13111–13115
Benson LV, Stein JR, Taylor HE (2009) Possible sources of archaeo-logical maize found in Chaco Canyon and Aztec Ruin, NewMexico. J Archaeol Sci 36(2):387–407
Benson LV, Taylor HE, Plowman TI, Roth DA, Antweiler RC (2010)The cleaning of burned and contaminated archaeological maizeprior to 87Sr/86Sr analysis. J Archaeol Sci 37(1):84–91
Bentley RA (2006) Strontium isotopes from the Earth to the archaeo-logical skeleton: a review. J Archaeol Method Theory 13(3):135–187
Blum JD, Taliaferro EH, Weisse MT, Holmes RT (2000) Changes in Sr/Ca, Ba/Ca, and 87Sr/86Sr ratios between trophic levels in twoforest ecosystems in the northeastern USA. Biogeochem 49:87–101
Bogaard A, Heaton THE, Poulton P, Merbach I (2007) The impact ofmanuring on nitrogen isotope ratios in cereals: archaeologicalimplications for reconstruction of diet and crop management prac-tices. J Archaeol Sci 34(3):335–343
Britton K, Grimes V, Dau J, Richards MP (2009) Reconstructing faunalmigrations using intra-tooth sampling and strontium and oxygenisotope analyses: a case study of modern caribou (Rangifertarandus granti). J Archaeol Sci 36(5):1163–1172
Archaeol Anthropol Sci
Britton K, Grimes V, Niven L, Steele TE, McPherron S, Soressi M, KellyTE, Jaubert J, Hublin J-J, Richards MP (2011) Strontium isotopeevidence for migration in late Pleistocene Rangifer: implications forneanderthal hunting strategies at the Middle Palaeolithic site of Jonzac,France. J Hum Evol 61(2):176–185. doi:10.1016/j.jhevol.2011.03.004
Buzon MR, Conlee CA, Bowen GJ (2011) Refining oxygen isotopeanalysis in the Nasca region of Peru: an investigation of water sourcesand archaeological samples. Int J Osteoarchaeol 21(4):446–455.doi:10.1002/oa.1151
Buzon MR, Conlee CA, Simonetti A, Bowen GJ (2012) The conse-quences of Wari contact in the Nasca region during the MiddleHorizon: archaeological, skeletal, and isotopic evidence. JArchaeol Sci 39(8):2627–2636. doi:10.1016/j.jas.2012.04.003
Chepstow-Lusty A, Frogley MR, Bauer BS, Bush MB, Herrera AT(2003) A late Holocene record of arid events from the Cuzcoregion, Peru. J Quatern Sci 18(6):491–502
Conlee CA, BuzonMR, Gutierrez AN, Simonetti A, Creaser RA (2009)Identifying foreigners versus locals in a burial population fromNasca, Peru: an investigation using strontium isotope analysis. JArchaeol Sci 36(12):2755–2764
Coudrain A, Loubet M, Condom T, Talbi A, Ribstein P, Pouyaud B,Quintanilla J, Dieulin C, Dupre B (2002) Données isotopiques(87Sr/86Sr) et changements hydrologiques depuis 15 000 ans surl'Altiplano andin (Isotopic Data (87Sr/86Sr) and hydrologicalchanges during the last 15,000 years on the Andean altiplano).Hydrol Sci J 47(2):293–306
Craig N, Aldenderfer MS, Rigsby CA, Baker PA, Blanco LF (2011)Geologic constraints on rain-fed qocha reservoir agricultural in-frastructure, northern lake Titicaca Basin, Peru. J Archaeol Sci38(11):2897–2907. doi:10.1016/j.jas.2011.05.005
Erickson CL (1988) Raised field agriculture in the Lake Titicaca Basin:putting ancient agriculture back to work. Expedition 30(3):8–16
Ericson JE (1985) Strontium isotope characterization in the study ofprehistoric human ecology. J Hum Evol 14:503–514
Evans JA, Tatham S (2004) Defining 'local signature' in terms of Srisotope composition using a tenth-to twelfth-century Anglo-Saxonpopulation living on a Jurassic clay-carbonate terrain, Rutland. UKForensic Geosci 232:237–248
Evans JA, Montgomery J, Wildman G, Boulton N (2010) Spatialvariations in biosphere 87Sr/86Sr in Britain. J Geo Soc 167:1–4
Faure G (1986) Principles of isotope geology. Wiley, New YorkFinucane B (2007) Mummies, maize, and manure: multi-tissue stable
isotope analysis of late prehistoric human remains from theAyacucho Valley, Peru. J Archaeol Sci 34(12):2115–2124
Fisher JL, Valentine B (2013) Resource depression, climate change, andmountain sheep in the eastern Great Basin of Western NorthAmerica. Archaeol Anthropol Sci 5(2):145–157. doi:10.1007/s12520-013-0124-9
Francis PW, Moorbath S, Thorpe RS (1977) Strontium isotope data forrecent andesites in Ecuador and North Chile. Earth Planet Sci Lett37(2):197–202
Frei KM, Frei R, Mannering U, Gleba M, Nosch ML, Lyngstrom H(2009a) Provenance of ancient textiles: a pilot study evaluating thestrontium isotope system in wool. Archaeometry 51(2):252–276
Frei KM, Skals I, Gleba M, Lyngstrøm H (2009b) The Huldremose IronAge textiles, Denmark: an attempt to define their provenance apply-ing the strontium isotope system. j archaeol sci 36(9):1965–1971
Gil AF, Neme GA, Ugan A, Tykot RH (2011) Oxygen isotopes andhuman residential mobility in Central Western Argentina. Inter JOsteoarchaeol.n/a-n/a. doi:10.1002/oa.1304
Graffam G (1992) Beyond state collapse: rural history, raised fields, andpastoralism in the south Andes. American Anthropol 94(4):882–904
Gregory HE (1916) Geologic reconnaissance of the Cuzco Valley.Amer J Sci 41:1–100
Gregory-Wodzicki K (2000) Uplift history of the central and northernAndes: a review. Geo Soc Amer Bull 112:1092–1105
Grousset FE, Rognon P, Coudé-Gaussen G, Pédemay P (1992) Originsof peri-Saharan dust deposits traced by their Nd and Sr isotopiccomposition. Palaeogeograph Palaeoclimatol Palaeoecol 93:203–212
Grove MJ, Baker PA, Cross SL, Rigsby CA, Seltzer GO (2003)Application of strontium isotopes to understanding the hydrologyand paleohydrology of the altiplano, Bolivia-Peru. PaleogeographPaleoclim Paleoecol 194:281–297
Harmon RS, Barreiro BA, Moorbath S, Hoefs J, Francis PW, ThorpeRS, Déruelle B, McHugh J, Viglino JA (1984) Regional O-, Sr-,and Pb-isotope relationships in late Cenozoic calc-alkaline lavas ofthe Andean Cordillera. J Geol Soc London 141:803–822
Hawkesworth CJ, Hammill M, Gledhill AR, van Calsteren P, Rogers G(1982) Isotope and trace element evidence for late-stage intra-crustalmelting in the high Andes. Earth Planet Sci Lett 58:240–254
Hedman KM, Curry BB, Johnson TM, Fullagar PD, Emerson TE(2009) Variation in strontium isotope ratios of archaeologicalfauna in the Midwestern United States: a preliminary study. JArchaeol Sci 36(1):64–73
Heier A, Evans JA, Montgomery J (2009) The potential of carbonizedgrain to preserve biogenic 87Sr/86Sr signatures within the burialenvironment. Archaeometr 51(2):277–291
Hodell DA, Quinn RL, Brenner M, Kamenov G (2004) Spatial variationof strontium isotopes (87Sr/86Sr) in the Maya region: a tool fortracking ancient human migration. J Archaeol Sci 31:585–601
Horn P, Holzl S, Rummel S, Aberg G, Schiegel S, Biermann D, StruckU, Rossman A (2009) Humans and camelids in river oases of theIca-Palpa-Nazca region in pre-Hispanic times—insights from H-C-N-O-S-Sr isotope signatures. In: Reindel M, Wagner GA (eds)New technologies for archaeology. Springer, Berlin, pp 173–192
James DE (1982) A combined O, Sr, Nd, and Pb isotopic and traceelement study of crustal contamination in central Andean lavas. I.Local geochemical variations. Earth Planet Sci Lett 57:47–62
Janusek JW, Kolata A (2004) Top-down or bottom-up: rural settlementand raised field agriculture in the Lake Titicaca Basin, Bolivia. JAnthropol Archaeol 123(4):404–430
Johnson CE, Johnson AH, Siccama TG (1991) Whole-tree clear-cuttingeffects on exchangeable cations and soil acidity. Soil Sci Soc Am J55(2):502–508. doi:10.2136/sssaj1991.03615995005500020035x
Julien C (1985) Guano and resource control in sixteenth-centuryArequipa. In: Masuda S, Shimada I, Morris C (eds) Andean ecologyand civilization. University of Tokyo Press, Tokyo, pp 185–231
Klerkx J, Deutsch S, Pichler H, Zeil W (1977) Strontium isotopiccomposition and trace element data bearing on the origin ofCenozoic volcanic rocks of the central and southern Andes. JVolcanol Geotherm Res 2:49–71
Knudson KJ (2007) La influencia de Tiwanaku en San Pedro deAtacama: una investigación utilizando el análisis de isótopes delestroncio. Estud Atacameños 33:7–24
Knudson KJ (2008) Tiwanaku influence in the South Central Andes:strontium isotope analysis and Middle Horizon migration. LatAmer Antiq 19(1):3–23
Knudson KJ (2009) Oxygen isotope analysis in a land of environmentalextremes: the complexities of isotopic work in the Andes. Int JOsteoarchaeol 19(2):171–191
Knudson KJ, Buikstra JE (2007) Residential mobility and resource usein the Chiribaya polity of southern Peru: strontium isotope analysisof archaeological tooth enamel and bone. Int J Osteoarchaeol17(6):563–580
Knudson KJ, Price TD (2007) Utility of multiple chemical techniques inarchaeological residential mobility studies: case studies fromTiwanaku- and Chiribaya-affiliated sites in the Andes. Am JPhys Anthropol 132(1):25–39
Knudson KJ, Torres-Rouff C (2009) Investigating cultural heterogene-ity in San Pedro de Atacama, northern Chile through biogeochem-istry and bioarchaeology. Am J Phys Anthropol 138(4):473–485
Archaeol Anthropol Sci
Knudson KJ, Tung TA (2007) Using archaeological chemistry to in-vestigate the geographic origins of trophy heads in the centralAndes: strontium isotope analysis at the Wari site of Conchopata.In: Glascock MD, Speakman RJ, Popelka-Filcoff RS (eds)Archaeological chemistry: analytical techniques and archaeologi-cal interpretation, vol 968. ACS Symposium Series. AmericanChemical Society, Washington D.C., pp 99–113
Knudson KJ, Tung TA (2011) Investigating regional mobility in thesouthern hinterland of the Wari Empire: biogeochemistry at thesite of Beringa, Peru. Amer J Phys Anthropol 145(2):299–310
Knudson KJ, Price TD, Buikstra JE, Blom DE (2004) The use ofstrontium isotope analysis to investigate Tiwanaku migration andmortuary ritual in Bolivia and Peru. Archaeomet 46(1):5–18
Knudson KJ, Tung T, Nystrom KC, Price TD, Fullagar PD (2005) Theorigin of the Juch'uypampa cave mummies: strontium isotopeanalysis of archaeological human remains from Bolivia. JArchaeol Sci 32:903–913
Knudson KJ, Williams SR, Osborne R, Forgey K, Williams PR (2009)The geographic origins of Nasca trophy heads in the Kroebercollection using strontium, oxygen, and carbon isotope data. JAnthropol Archaeol 28(2):244–257
Knudson KJ, Gardella KR, Yaeger J (2012a) Provisioning Inka feasts atTiwanaku, Bolivia: the geographic origins of camelids in thePumapunku complex. J Archaeol Sci 39(2):479–491. doi:10.1016/j.jas.2011.10.003
Knudson KJ, Pestle WJ, Torres-Rouff C, Pimentel G (2012b) Assessingthe life history of an Andean traveler through biogeochemistry:stable and radiogenic isotope analyses of archaeological humanremains from northern Chile. Inter J Osteoarchaeol 22(4):435–451
Lucas CA (2012) People on the move: examining Tiwanaku stateexpansion in the Cochabamba Valley through strontium isotopeanalysis. Northern Arizona University, Flagstaff
Marsteller SJ, Torres-Rouff C, Knudson KJ (2011) Pre-Columbian sick-ness ideology and the social experience of leishmaniasis: a contex-tualized analysis of bioarchaeological and paleopathological datafrom San Pedro de Atacama. Chile Inter J Paleopathol 1:24–34
McNutt RH, Crockett JH, Clark AH, Caelles JC, Farrar E, Haynes SJ,Zentilli M (1975) Initial 87Sr/86Sr ratios of plutonic and volcanicrocks of the central Andes between latitudes 26 and 29 degreessouth. Earth Planet Sci Lett 27:305–313
Meharg AA, Deacon C, Edwards KJ, Donaldson M, Davidson DA,Spring C, Scrimgeour CM, Feldmann J, Rabb A (2006) Ancientmanuring practices pollute arable soils at the St Kilda WorldHeritage Site, Scottish North Atlantic. Chemosphere 64(11):1818–1828. doi:10.1016/j.chemosphere.2006.01.076
Miyamoto T, Hamamoto R, Yanagi T (2010) Sr and Nd isotope com-positions of atmospheric mineral dust at the summit of Mt. Sefuri,North Kyushu, southwest Japan: a marker of the dust provenanceand seasonal variability. Geochim Cosmochim Acta 74(5):1471–1484
Nado KL, Marsteller SJ, King LM, Daverman BM, Torres-Rouff C,Knudson KJ (2012) Examining local social identities throughpatterns of biological and cultural variation in the Solcor ayllu,San Pedro de Atacama. Chungará 44(2):341–357
Négrel P, Deschamps P (1996) Natural and anthropogenic budgets of asmall watershed in the Massif Central (France): chemical andstrontium isotopic characterization of water and sediments.Aquat Geochem 2(1):1–27
Notsu K, Lajo JA (1984) Regional variation of 87Sr/86Sr ratio in LateCenozoic volcanic rocks from southern Peru. Geochemic J18(5):241–250
Price TD, Grupe G, Schroter P (1994a) Reconstruction of migrationpatterns in the Bell Beaker Period by stable strontium isotopeanalysis. Appl Geochem 9:413–417
Price TD, Johnson CM, Ezzo JA, Ericson J, Burton JH (1994b)Residential mobility in the prehistoric southwest United States: a
preliminary study using strontium isotope analysis. J Archaeol Sci21:315–330
Price TD, Burton JH, Bentley RA (2002) The characterization ofbiologically available strontium isotope ratios for the study ofprehistoric migration. Archaeomet 44(1):117–136
Price TD, Bokelmann K, Pike-Tay A (2008) Late Paleolithic reindeeron the North European Plain. In: Sulgostowska Z, TomarazewskiAJ (eds) Man, millenia, environment: studies in honor of RomualdSchild. Polish Academy of Sciences, Warsaw, pp 123–131
Rogers G, Hawkesworth CJ (1989) A geochemical traverse across theNorth Chilean Andes: evidence for crust generation from themantle wedge. Earth Planet Sci Lett 91:271–285
Runia LT (1987) Strontium and calcium distribution in plants: effect onpalaeodietary studies. J Archaeol Sci 14(6):599–608
Shaw BJ, Summerhayes GR, Buckley HR, Baker JA (2009) The use ofstrontium isotopes as an indicator of migration in human and pigLapita populations in the Bismarck Archipelago, Papua NewGuinea. J Archaeol Sci 36(4):1079–1091
Slovak NM, Paytan A, Wiegand BA (2009) Reconstructing MiddleHorizon mobility patterns on the coast of Peru through strontiumisotope analysis. J Archaeol Sci 36(1):157–165
Stein M, Starinsky A, Goldstein SL, Katz A, Machlus M, Schramm A(1997) Strontium isotopic, chemical, and sedimentological evi-dence for the evolution of Lake Lisan and the Dead Sea.Geochim Cosmochim Acta 61(18):3975–3992
Sykes NJ, White J, Hayes TE, Palmer MR (2006) Tracking animalsusing strontium isotopes in teeth: the role of fallow deer (Damadama) in Roman Britain. Antiq 80:948–959
Sykes NJ, Baker KH, Carden RF, Higham TFG, Hoelzel AR, StevensRE (2011) New evidence for the establishment and management ofthe European fallow deer (Dama dama dama) in Roman Britain. JArchaeol Sci 38(1):156–165
Thornton EK (2011) Reconstructing ancient Maya animal trade throughstrontium isotope (87Sr/86Sr) analysis. J Archaeol Sci38(12):3254–3263. doi:10.1016/j.jas.2011.06.035
Thornton EK, DeFrance SD, Krigbaum JS, Williams PR (2011)Isotopic evidence for Middle Horizon to 16th century camelidherding in the Osmore Valley, Peru. Int J Osteoarchaeol21(5):544–567
Tung TA, Knudson KJ (2008) Social identities and geographical originsof Wari trophy heads from Conchopata, Peru. Curr Anthropol49(5):915–925
Tung TA, Knudson KJ (2010) Childhood lost: abductions, sacrifice, andtrophy heads of children in the Wari Empire. Lat Amer Antiq21(1):44–66
Tung TA, Knudson KJ (2011) Identifying locals, migrants, and captivesin the Wari heartland: a bioarchaeological and biogeochemicalstudy of human remains from Conchopata, Peru. J AnthropolArchaeol 30(3):247–261. doi:10.1016/j.jaa.2011.06.005
Turner BL, Armelagos GJ (2012) Diet, residential origin, and pathologyat Machu Picchu, Peru. Am J Phys Anthropol 149(1):71–83
Turner BL, Kamenov GD, Kingston JD, Armelagos GJ (2009) Insightsinto immigration and social class at Machu Picchu, Peru based onoxygen, strontium, and lead isotopic analysis. J Archaeol Sci36(2):317–332
Ugan A, Neme G, Gil A, Coltrain J, Tykot R, Novellino P (2012)Geographic variation in bone carbonate and water delta18O valuesin Mendoza, Argentina and their relationship to prehistoric econ-omy and settlement. J Archaeol Sci 39(8):2752–2763.doi:10.1016/j.jas.2012.04.013
Veizer J (1989) Strontium isotopes in seawater through time. Annu RevEarth Planet Sci 1:141–167
Viner S, Evans J, Albarella U, Parker Pearson M (2010) Cattle mobilityin prehistoric Britain: strontium isotope analysis of cattle teethfrom Durrington Walls (Wiltshire, Britain). J Archaeol Sci37(11):2812–2820
Archaeol Anthropol Sci
Webb EC,White CD, Longstaffe FJ (2013) Exploring geographic originsat Cahuachi using stable isotopic analysis of archaeological humantissues and modern environmental waters. Inter J Osteoarch. (inpress)
Wernke S (2007) Negotiating community and landscape in the PeruvianAndes: a transconquest view. Amer Anthropol 109(1):130–152
Wernke S (2010) A reduced landscape: toward a multi-causal under-standing of historic period agricultural deintensification in high-land Peru. J Lat Amer Geog 9(3):51–83
Whipkey CE, Capo RC, Chadwick OA, Stewart BW (2000) The im-portance of sea spray to the cation budget of a coastal Hawaiiansoil: a strontium isotope approach. Chem Geol 168(1–2):37–48
White CD, Price TD, Longstaffe FJ (2007) Residential histories of thehuman sacrifices at the Moon Pyramid. Teotihuacan 18(1):159–172
White CD, Nelson AJ, Longstaffe FJ, Grupe G, Jung A (2009)Landscape bioarchaeology at Pacatnamu, Peru: inferring mobilityfrom [delta]13C and [delta]15N values of hair. J Archaeol Sci36(7):1527–1537
Wu G, Zhang C, Zhang X, Tian L, Yao T (2010) Sr and Ndisotopic composition of dust in Dunde ice core, NorthernChina: implications for source tracing and use as an analogueof long-range transported Asian dust. Earth Planet Sci Lett299(3–4):409–416
Archaeol Anthropol Sci
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