Oxygen and strontium isotope tracing of human migration at the Bell Beaker site Le Tumulus des Sables, France
Malte Willmes, Hannah James, Ceridwen Boel, Patrice Courtaud, Antoine Chancerel, Linda McMorrow, Richard Armstrong, Les Kinsley, Maxime Aubert, Stephen Eggins, Ian Moffat, and Rainer Grün
The Australian National University, Research School of Earth Sciences, Canberra, Australia, ([email protected])
Isotope mapping
Introduction
Strontium Isotopes
Oxygen (δ18O) and strontium (87Sr/86Sr) isotope values of tooth enamel and dentine record the avaerage dietary signature
ingested by that individual during their childhood. When this data is compared to the isotope signature of the burial site it
can be used to indicate if the individual migrated into this area during their lifetime.
Aim
Investigate human migration at the early Bell Beaker site (2500-2000 BC) Le Tumulus des Sables, France,
using oxygen (δ18O) and strontium (87Sr/86Sr) isotopes of tooth enamel and dentine.
87Sr/86Sr
0.740
75th percentile
Median
25th precentile
0.736
2°0'0"E
Le Tumulus des sables
45°0'0"N
0.728
0.724
3°0'0"E
Massif Central
Sample location
Le Tumulus des sables
9th percentile
0.732
87Sr/86Sr
1°0'0"E
Bordeaux
0.720
0.716
0.712
Aquitaine Basin
(q Le T
ge
2- u
ne
3 m
,Q
(b u
Q
ua
ua -h- lus
te
te t), de
rn
rn q s
ar
ar 2- Sa
Pa
y
y 3 b
le
(
pq Q (q2 (m les
og
1 u , q -ten
(b at 2 p)
e,
-h er -3 )
N
-t) na , q
eo
, p ry 3)
ge
q1 (p
ne
q
(g
N (m- 1)
m
eo t(b N ge p))
-h eo ne
-t g
Pa ), g ene (p)
Pa leo m ( (m
le ge m )
o n -t
Cr gen e (g -p))
et e ( , g
Ro Ju aceo e, e m)
ch ras us 1, e
ec si (c 2)
ho c ( 1,
Ca
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im , j
Ca oni
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on ou er ti
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Ca fero (h1 ian s
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D nife 17, , h3
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on us ,
ia (1 19
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O
r
Ca do D (d, d , 16
e
)
Ca mbr vici von 1, d
m ian an ian 2)
br , (o (
ia Or , o 14
n, d 1 )
N N
O ov , o
eo eo
rd ic s)
ov ian
pr pr
ot ot P
er er al C icia (7)
oz oz eo am n
(
o
N ic, oic, zoic bria ko)
eo C O ( n
pr am rd gla (k
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er ria vi (f- )
oz n cia p)
oi (b n )
c, , (b
Ca b2 o)
m k, b
br k
ia )
n
(6
)
0.704
44°0'0"N
44°0'0"N
0.708
Bayonne
ar
y
Toulouse
Fig. 1: Box-and-whisker plot of the bioavailable Sr isotope composition ranges
for the geologic units of the Aquitaine Basin, Pyrenees and Massif Central
43°0'0"N
N
eo
43°0'0"N
rn
te
ua
Q
. 26 individuals (18 adult, 8 juvenile) were chosen for this study. The left upper second molar (LM2) was chosen for the
adult samples and the left deciduous upper second incisor (Ldi2) for juveniles to ensure that each tooth represents a
different individual.
. diagenetic overprint of the teeth was investigated using Uranium (U) and Thorium (Th )concentrations measured on a
Laser-ablation-ICP-MS
. δ18O isotopes were analysed in-situ by Sensitive High Resolution Ion Micro Probe (SHRIMP).
. 87Sr/86Sr isotopes analysis involved drilling a 0.2-0.5 mg sample of enamel and dentine from the tooth. The Sr was then
chemically separated and analysed by Thermal Ionization Mass Spectrometry (TIMS).
. the results from the human remains were then compared to a δ18O isoscape of Europe (waterisotopes.org) and
bioavailable 87Sr/86Sr isotope data (fauna, plants, soils) from the IRHUM database (www.irhumdatabase.com).
0
25
Human migration at Le Tumulus des Sables
Pyrenees
50 Kilometers
Enamel
0.720
3°0'0"E
Devonian
14
plutonic
o, o1, os
sedimentary,
volcanic
7
metamorphic
ko
metamorphic
{
Soil
Neogene
m
sedimentary
Paleogene,
Neogene
gm (b-h-t), gm
(m-t-p)
volcanic
Paleogene
g, gm
sedimentary
Ordovician
Cambrian,
Ordovician
Cambrian,
Ordovician
Paleogene
e, e1, e2
sedimentary
Cambrian
k
Sedimentary,
volcanic,
metamorphic
Cretaceous
c1, c2
sedimentary
Paleozoic
gla (f-p)
metamorphic
bo
metamorphic
Jurassic
j1, j2, j3
Rochechouart
impactites
Impactites de
Rochechouart
impactites
Permian
r
sedimentary
Neoproterozoic,
Ordovician
Neoproterozoic,
Cambrian
Neoproterozoic,
Cambrian
sedimentary
b, b2k, bk
6
0.710
60°0'0"N
0
110
220
0°0'0"
10°0'0"E
20°0'0"E
16
Scanning for diagenetic overprinting
14
A02 - SLMEM900
A03 - SLMEM454
Introduction
. dental material is affected by both physical and
chemical changes after burial, potentially leading to the
loss of the original O and Sr isotope composition.
A05 - SLMEM308
12
0.709
0.708
10
0.707
metamorphic,
sedimentary
plutonic,
metamorphic
0.706
Oxygen isotopes
The δ18O isotopic composition of meteoric water changes depending on climate, temperature and quantity of
precipitation. δ18O isotope ratios in skeletal and dental remains are related to body water, which in turn is
influenced by diet, physiology and climate.
10°0'0"W
0.712
0.711
0.705
Fig. 2: Overview of geologic units surrounding Le Tumulus des Sables
from the 1:1M geologic map of France (Chantraine et al., 2005)
Fig. 3: Strontium isotope cycle
0.713
18
87
86
Fig. 6: Sr/ Sr isotope ratios of the human teeth from Le Tumulus des Sables
30°0'0"E
440 Kilometers
8
A1
A2
A3
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15
A16
A17
A18
J1
J2
J3
J6
J7
J8
U1
U2
U3
sedimentary
18
p
δ O (‰)
Neogene
0.714
J08 - SLMEM276
d, d1, d2
J07 - SLMEM86
Devonian
0.715
J06 - SLMEM1192
volcanic
sedimentary,
volcanic,
metamorphic
J05 - SLMEM102
pq1 (b-h-t), pq1
(m-t-p)
Fig. 8: Top: Distribution of Bell Beaker people in Europe (Vander Linden, 2006)
and typical artefacts. Bottom: Excavation at Le Tumulus des Sables
20
J04 - SLMEM119
Neogene,
Quaternary
0.716
J03 - SLMEM1251
plutonic
J02 - SLMEM66
15, 16
J01 - SLMEM291
Carboniferous
A18 - SLMEM5
sedimentary
A17 - SLMEM509
pq1
A16 - SLMEM298
Quaternary
A15 - SLMEM491
plutonic
A14 - SLMEM1289
17, 18, 19
A13 - SLMEM1094
Carboniferous
A12 - SLMEM1007
sedimentary
A11- SLMEM861
q2, q2-3, q3
A10 - SLMEM813
Quaternary
22
0.717
A09 - SLMEM112
sedimentary
A08 - SLMEM432
h1, h2, h3
A07 - SLMEM1157
Carboniferous
A06 - SLMEM282
volcanic
0.718
A05 - SLMEM308
Quaternary
q2-3 (b-h-t), q23 (m-t-p)
A04- SLMEM466
Lithologies
A03 - SLMEM454
ID
A02 - SLMEM900
Geologic unit
24
0.719
A01 - SLMEM263
Lithologies
uptake of labile strontium
Bedrock
2°0'0"E
ID
strontium enters the food chain
87Sr/86Sr depends on age and composition
1°0'0"E
Geologic unit
strontium subsitutes for calcium in teeth and bones
weathering
0°0'0"
60°0'0"N
Plants
1°0'0"W
87Sr/86Sr
2°0'0"W
Le Tumulus des Sables
. located in the town of Saint-Laurent-Médoc, in the Gironde
department, France
. it is a collective burial contained to a roughly circular raised
mound 7x8 m and the human remains are highly
disarticulated and fragmented
. identified as a Bell Beaker site based on characteristic
artefacts and dating of a bone fragment (2490- 2290 cal. BC.)
The site fills an important geographic gap for investigating the
proposed migration of the Bell Beaker from the Iberian
Peninsula
Quaternary and Neogene sediments
Le Tumulus des Sables
Dentine
Le Tumulus des Sables
precipitation
18
Fig. 7: δ O values for the human teeth from Le Tumulus des Sables
. 17 individuals show 87Sr/86Sr isotope ratios within the bioavailable 87Sr/86Sr isotope range of the site and the remaining 9
within the range of the surrounding Quaternary and Neogene sediment units of the Aquitaine Basin indicating only
limited mobility.
1000
Sr
Th
U
1000
Sr
Th
U
1000
100
100
100
10
10
10
1
1
Sr
Th
U
1
0.1
0.1
0.1
0.01
0.01
0.01
A06 - SLMEM282
A12 - SLMEM1007
A15 - SLMEM491
1000
1000
1000
Le Tumulus des Sables
-10
-11
-12
-13
50°0'0"N
50°0'0"N
-14.63
Fig. 4: Oxygen isotopes in the hydrological cycle (Versteegh, Emma, 2012)
40°0'0"N
40°0'0"N
The incorporation of oxygen isotopes into skeletal
tissues involves physiological mass fractionation. To
compare δ18O values in teeth with those in the
environment, the data measured on the enamel need
conversion into water.
δ18Owater = 1.54(±0.09) δ18Ophosphate - 33.72(±1.51)
Daux et al. (2008)
Le Tumulus des Sables
10°0'0"W
0°0'0"
10°0'0"E
18
20°0'0"E
Fig. 5: Oxygen isotope (δ O) in precipitation for Europe (waterisotopes.org)
. based on the combination of δ18O and 87Sr/86Sr isotope tracing we interpret 24 of the individuals at Le Tumulus des
Sables to represent a local population with limited mobility and 2 possible migrants from the southern Iberian Peninsula,
or northern Africa. This represents a low degree of mobility for the Bell Beaker at Le Tumulus des Sables, which is in
contrast to findings at other Bell Beaker sites in Europe and shows that there is variation in the degree of mobility within
the Bell Beaker Phenomenon.
Future directions
87Sr/86Sr
Detailed mapping of bioavailable
isotope ratios in Spain, Portugal and northern Africa, as well as the use of
additional isotope tracers, such as Pb isotopes, can be used to better constrain provenance and enhance our understanding
of Bell Beaker mobility.
Sr
Th
U
100
10
1
Sr
Th
U
100
100
10
10
ppm
-9
1
0.1
0.1
0.01
0.01
0.01
J05 - SLMEM102
J06 - SLMEM1192
1000
1000
Sr
Th
U
Sr
Th
Sr
Th
U
1
0.1
J08 - SLMEM276
U
1000
100
100
100
10
10
10
ppm
-8
ppm
-7
ppm
-6
ppm
18
δ O [‰]
-4.48
-5
ppm
. the δ18O isotope values add support to this hypothesis but also identifies two possible migrants from the southern
Iberian Peninsula or northern Africa. The two possible migrants did not show 87Sr/86Sr isotope ratios outside of the
bioavailable 87Sr/86Sr isotope range of the burial and surrounding geologic units. This indicates that they could have
come from an area with a similar 87Sr/86Sr isotope range as the Aquitaine Basin.
Mean Annual Precipitation
Le Tumulus des
Sables
The large geographic distribution of the Bell Beaker has led to
different interpretations including the migration of a unique
population into Europe, long distance exchange of prestige
goods, and diffusion of cultural components without
movement of people.
ppm
Outlier
91th percentile
0°0'0"
45°0'0"N
0.744
1°0'0"W
Bell Beaker
. characterised by a distinctive artefact assemblage
. widespread across Europe with a southwest-northeast trend
in appearance and a possible origin on the Iberian Peninsula
. occurring around the transition from the Neolithic to the
Bronze Age around 3000 BC - 1,800 BC.
ppm
2°0'0"W
Analytical methods
46°0'0"N
isotope ratios vary between different geologic regions, depending on their age and composition. Sr is
released through weathering and transported into the soil, ground and surface water, where it becomes available
for uptake by plants, enters the food cycle and eventually ends up in skeletal and dental tissue where it substitutes
for calcium. Soil and plant samples from the IRHUM (Isotopic Reconstruction of Human Migration) database were
used to infer the bioavailable 87Sr/86Sr isotope range for southern France. In total 400 soil and plant samples from
235 sample locations in southern France covering the Aquitaine Basin, the Pyrenees, and Massif Central were
chosen from the database, leaving out sample sites likely contaminated by recent anthropogenic influences. Soil
and plant samples were chosen because they provide a good estimate of the variation of the bioavailable 87Sr/86Sr
isotope ratio at a single location.
Archaeological background
ppm
IRHUM
1
1
1
0.1
0.1
0.1
0.01
0.01
0.01
Sr
Th
U
. modern teeth contain only trace amounts of uranium
and thorium and thus their presence in archaeological
remains can be used to identify zones of diagenetic
overprinting. Uranium is water soluble and highly
mobile and indicates chemical overprinting, whereas
thorium is water insoluble and represents mechanical
overprinting of the sample.
Results
. the majority of samples show an increase in U and Sr
concentrations from the enamel into the dentine, with
lowest U concentrations occurring close to the surface
of the enamel.
. these low U zones are interpreted to have most-likely
preserved the original Sr isotope ratio
. higher U concentrations, mainly found in the dentine,
are interpreted as a sign of diagenetic overprinting
. Th concentrations in all samples are below the
detection limit indicating that there is no significant
contribution of sediment grains.
Fig. 9: Selected results for U (green), Th (red) and Sr (blue) concentration profiles for the teeth
from Le Tumulus des Sables. They are measured as tracks starting in the enamel going into the
dentine.