fingerprinting ancient egyptian quarries: preliminary results using laser ablation...
TRANSCRIPT
Archaeometry 41. 2 (1999). 227-238. Printed in Great Britain
FINGERPRINTING ANCIENT EGYPTIAN QUARRIES: PRELIMINARY RESULTS USING LASER ABLATION
SPECTROMETRY * MICROPROBE-INDUCTIVELY COUPLED PLASMA-MASS
L. M. MALLORY-GREENOUGH,' J. D. GREENOUGH,' G. DOBOS12 and J. V. OWEN3
'Department of Earth and Environmental Sciences, Okanagan University College, 3333 College Way, Kelowna, BC, V1 V 1 V7, Canada
2Department of Earth Sciences, Memorial University of Newfoundland, St. John's, NF, AIB 3x5, Canada 3Departmenr of Geology, Saint Mary's University, Halt@, NS, B3H 3C3. Canada
Microchemical analysis of minerals present in pottery and stone artefacts may help determine their provenance. Electron microprobe major element analyses of augite suggest that minor elements (Ti02, MnO, Na20) are important in jingerprinting basalts. This points to the potential usefulness of trace elements. Augite present in six basalt samples (representing all knowdsuspected Pharaonic basalt quarries in northern and middle Egypt) and basaltic temper fragments in two New Kingdom pottery sherds was analysed for 28 trace elements (Sr, Ba, Th, U, Zr, Hf; Nb, Ta, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Lly, Ho, Er, Tm, Yb, Lu, Sc, V, Cr, Ni, Ga) by laser ablation microprobe-inductively coupled plasma-mass spectrometry (LAM-ICP-MS, laserprobe). Cluster and discriminant analysis indicate that ( I ) laserprobe trace element data are more effective at jingerprinting basalts than conventional electron- microprobe data and (2) basaltic temper in the two sherds does not match any of the quarries. Microbeam techniques providing trace element data may represent the future for mineral-based
provenance studies.
KEYWORDS: EGYPT, NEW KINGDOM, LASER ABLATION MICROPROBE-INDUCTIVELY COUPLED PLASMA-MASS SPECTROMETRY, POTERY, STONE, BASALT, PYROXENE,
TEMPER, TRACE ELEMENTS, PETROLOGY, PROVENANCE
INTRODUCTION
Petrographic analysis of temper can separate local from exotic pottery given a detailed data base of nearby lithologies (Williams 1983; Mallory-Greenough et al. 1998). Bizarre or rare rock types are easier to source than those which are more common. For example, basalts contain pyroxene (augite), plagioclase (labradorite) and Fe-Ti oxides (magnetite-ilmenite). Although low Ca-pyroxene (pigeonite or orthopyroxene) and olivine are variably present, for the most part one basalt looks very much like another. Chemical differences between basalts are useful for assessing sources but cannot be ascertained from traditional petrographic studies.
In two earlier investigations, electron microprobe analyses of augite and plagioclase from
* Received 10 December 1997. accepted 24 September 1998.
221
228 L. M. Mallory-Greenough, J. D. Greenough, G. Dobosi and J. V. Owen
Pharaonic Egyptian quarries (Mallory-Greenough et al. in press) and pottery temper fragments (Mallory-Greenough et al. 1998) were used to try and identify temper sources. Overlap between fragment and quarry mineral compositions yielded contiguous, inconclusive results. These, and earlier studies by Nisbet and Pearce (1977), showed that minor elements (c 4 wt%) in pyroxenes (e.g., augite) are more useful than major elements (>4wt%) in discriminating basalt sources. Apparently stoichiometry (the mineral formula) places constraints on major element variability. This implies that trace elements (< 0.1 wt%) should be more successful at ‘fingerprinting’ quarries. In general, trace element concentrations in minerals cannot be determined using the electron microprobe, but the laser ablation microprobe-inductively coupled plasma-mass spectrometer (LAM-ICP-MS or laserprobe) has this capability. We report on the trace element compositions of augites from samples of all known Pharaonic Egyptian basalt quarries and basaltic temper from two New Kingdom Egyptian pot sherds. Our results champion the quarry fingerprinting capabilities of the laserprobe.
QUARRY AND POTTERY SAMPLES
The unaltered condition and generally subalkaline nature (based on mineralogy and mineral chemistry) of at least some New Kingdom mafic temper fragments suggest their sources were Cretaceous and Tertiary basalts common in middle and northern Egypt (Meneisy 1990; Mallory- Greenough et al. 1998). Sampling concentrated on known or suspected Pharaonic quarries described in Lucas and Harris (1962, 62), Klemm and Klemm (1993) and Harrell and Bown (1995) which fit this profile. For convenience, all bedrock samples are referred to as ‘quarries’. The seven basalt samples represent four petrologicdgeochemical and geographical regions as defined below.
The Bahariya Oasis region is represented by the El Heluf basalt (sample H4), East Cairo region by the Cairo-Suez Road sample (CSRl), West Cairo region by Abu Roash (ARFl) and El Haddadin (HAD2, K32/2) samples, and Middle Egypt region by the Zarrouk (ZA) and Minya (BN) flows (see Fig. 1 for locations). Abu Zabaal was not sampled because it was probably not an ancient quarry site (Lucas and Harris 1962,62). In any event it represents another outcrop of the Haddadin-Abu Roash flow (Harrell and Bown 1995) of which there are three samples. Abdel Aal (1998) showed that trace element analyses of widely spaced samples along the Haddadin flow are within analytical error. This suggests extreme homogeneity in the quarried portions of thin Egyptian lava flows and implies that single samples of flows provide useful fingerprinting data.
All samples contain augite, plagioclase, Fe-Ti oxides and, with the exception of ZA (Zarrouk), olivine. Pigeonite occurs in the Cairo-Suez, El Haddadin and Minya samples and was reported from El Heluf (Awadallah 1980) and Abu Roash (El-Hinnawi and Maksoud 1968). Only ZA lacks pigeonite but unpublished whole-rock trace element data strongly suggest it is also subalkaline (e.g., NbN c 1.0). Matrix grain sizes range from 0.1 mm (Cairo-Suez sample) to 0.6 mm (Abu Roash), and El Haddadin samples contain large (- 1 cm) plagioclase phenocrysts. Most samples are subophitic with olivine, plagioclase and/or augite microphenocrysts. Abu Roash contains patches of clay minerals probably representing altered intersertal glass (green) and altered olivine (brown).
An examination of nine New Kingdom pottery sherds from Karnak temple excavations (courtesy of D. B. Redford, Akhenaten Temple Project) found fine-grained (< 100 p), unweath- ered, unmetamorphosed mafic (basaltic) rock fragments in three samples (FKI50, FKAX44, and
Fingerprinting ancient Egyptian quarries 229
Figure I Map of Egypt showing basalt outcrops (solid black), areas with Triassic to Tertiary mafc rocks (flows, sills, dykes and/or plugs; unjlled outlines, e.g., Bir Safsajl. Outcrop locations after Said (1962, 82, 153, 184, 198,207, 218); SaidandMartin (1964); El-HinnawiandMaksoud(1972); Awadallah (1980); Franzet al. (1987); Hubbardet al. (1987); Meneisy (1990).
TC1001). Eighteen fragments were examined by electron microprobe and nine of these (all in either sherd FKI50 or FKAX44) contained augite grains large enough (> 10 p in diameter) for analysis with the laserprobe.
PREVIOUS WORK A N D ANALYTICAL METHODS
A previous (Mallory-Greenough et al. in press) temper provenance investigation using augite and plagioclase major element compositions found the following: (1) the sources for many basalt fragments in the three New Kingdom pottery sherds examined are not clear (e.g., augite and plagioclase indicated different sources) suggesting there is/are undiscovered quarries, and (2) the minor elements (<4 wt%) in augite are more useful than the major elements (>4wt%) at
230 L. M . Mallory-Greenough, J. D. Greenough, G. Dobosi and J . V. Owen
identifying quarries. This suggests trace elements (< 0.1 wt%) could be extremely helpful in fingerprinting.
The laserprobe yields mineral trace element analyses by combining the high sensitivity of the ICP-MS with the microsampling ability of a laser (e.g., Longerich et al. 1993). Typical ablation pits are 10-5Op wide by -5Op deep. Argon carries vaporized mineral to the ICP-MS for analysis. Details of the laserprobe appear in Jackson et al. (1992), Longerich et al. (1993), Fryer et al. (1995) and Taylor er al. (1997). The Nd:YAG laser wavelength was quadrupled to 266 nm to enhance beam control and focusing. Beam size varied between 10 and 40 p. The largest beam possible was always used (determined by grain width), to maximize ablation yield and, thus, sensitivity. A polarizing optical attenuation system controlled beam intensity. The beam was aimed onto the sample, a thick (0.3mm) polished thin section, through a petrographic microscope. Isotopic analysis used a Fisons Instruments VG PQII+ ‘S’ enhanced sensitivity quadrupole ICP-MS with ‘time resolved analysis’ data acquisition software in fast, peak- jumping mode (8.3s dwell time per isotope). Data acquisition took -60s per spot for background (gas blank) followed by 60s €or ablation. Calibration used the spiked silicate glass NBS 612 measured twice at both the beginning and end of each 15 analysis run. In-run analysis of BCR-2 glass checked precision (reproducibility of a determined concentration) and accuracy (how close a determination is to the actual value) which are between 4 and 10%. Calcium from previous electron microprobe analyses (Mallory-Greenough ef al. in press) allowed correction for ablation yield differences between analyses. Data reduction utilized S. Jackson’s LAMTRACE spreadsheet. The data are available from the authors.
DATA PRESENTATION
Trace elements with the greatest potential for ’fingerprinting’ quarries have large differences between localities and little variation within a flow. For example, Sr shows tremendous variation between flows (23-52ppm; Table 1). Variation in Zr, Ta, La, Ce, Nd, Sc, V, Cr, Ni and Ga between flows may also be significant. Element selection for cluster analysis also used geochemical principles (see below, ‘Discussion’). Quarry and temper fragment analyses were clustered using methods and elements given in Figure 2. Two distinct sample groups (quarries and temper fragments) are apparent, suggesting that the quarries are not the temper sources. An exception, FKAX44 fragment 1, groups with Minya as in previous microprobe results (Mallory- Greenough et al. in press). Individual temper fragments tend to cluster together, but the groups are not as clear as the quarries, and the greater distances between them indicate they are very different from the quarries and one another. Well-defined quarry data clusters suggest that discriminant analysis may completely separate them.
DISCUSSION
An objective is to evaluate the laserprobe as a quarry discriminating tool. Thus, electron microprobe major element data are not utilized in the statistical analysis discussed below. Trace elements were selected based on differences in mean concentration (Table 1) and geochemical behaviour. Those reflecting mantle (see below) as opposed to differentiation processes may be more useful because thick basalt flows can chemically differentiate (Greenough and Dostal 1992; Goff 1996). Most large ion lithophile (e.g., Sr, Ba), high field strength (e.g., Th, U, Zr, Nb)
Fingerprinting ancient Egyptian quarries 23 1
DISTANCES 3.5 0.0
Figure 2 Cluster diagram comparing augites in quarry rocksamples (AR: Abu Roash; CS: Cairo-Suez Road; HF: El Heluf; HD: El Haddadin; MN: Minya; 24: Zarrouk) with temperfragment compositions. Quarry groups appearto the immediate left ofsamplenames(E1 HelufandEl HaddadinshortenedtoHelufandHaddadin), withregwnstothefarlefr(bold). Augitesfrom sherds F k X O and FKAX44 begin with 50 and 44, respectively, with fragment numbers as FI, F2, etc. Adjacent analyses and those forming limbs of a similarity tree tend to be most similar. ‘Distances’ provide a relative measure of how different analysesare. Data processing usedJOINinSYSTATsofhvare (Wilkinson etal. 1992)andinvolvedz-scoring Sr, Zr, Nb, La, Sc, V and Ga concentrations (ppm), calculating Euclidean distances and average linkage clustering. 2-scoring placed elements on the same scale for equal contribution to calculated distances. See text for discussion.
w
w
N
Tabl
e 1
Mea
n co
mpo
sitio
ns o
f quarry
augi
te
Are
a C
airo
-Sue
z El
Haa
iiadi
n El
Haa
iiadi
n A
bu R
oash
El
Hel
uf
Zarr
ouk
Min
ya
Sam
ple
CSR
I K
32n
H
AD
2 A
RF
l H
4 z
4
BN
No.
10
/15
1217
&/
I I
14
n
7/6
3640
5 9/
14
P
%
Maj
or e
lem
ents
- X
Si02
50
.7
Ti0
2 1.
03
FeO
13.1
3 MU0
0.36
M
go
14.7
C
aO
17.6
1 N
azO
0.
48
Tota
l 99
.99
A203
1.97
Trac
e el
emen
ts
-
X
Sr
23.3
Ba
1.
08
Th
0.02
4 U
0.
025
zr
17.3
Hf
1 Nb
0.
11
Ta
0.04
9 Y
15.1
La
0.
96
Ce
4.1
Pf 0.
93
Nd
5.69
Sm
2.
28
Eu
0.86
Gd
3.
05
U
0.62
0.
3 1.
2 2.
87
0.13
0.
94
1 .44
0.08
I7 6.5 1.01
0.
013
0.02
3.
86
0.3
0.1
0.02
1 2.
01
0.14
0.
57
0.12
0.
72
0.28
0.
1 0.
37
Tb
0.54
0.
09
-
X
50.7
1 1.
08
2.02
1 1
.27
0.31
15
.35
18.5
5 0.
47
99.7
7
-
X
25.7
0.
22
0.01
7
U
0.74
0.
16
0.95
2.
71
0.08
1.
11
1 0.08
U 1.84
0.
17
0.00
5
x 50
.78
0.97
1.
54
12.3
7 0.
31
14.5
8 18
.41
0.47
99
.43
-
X
23.9
0.
21
0.02
2
U
0.75
0.
24
0.43
3.
61
0.11
1.
78
1.23
0.
12
U 1.98
0.
13
0.00
8 bdl
bdl
22.7
5.
08
18.3
3.
53
1.3
0.38
1.
09
0.23
0.
11
0.03
0.
07
0.02
0.
027
0.01
4 0.
015
0.00
8 19
.3
3.26
15
.4
2.66
1.
55
0.31
1.
26
0.2
6.59
1.
25
5.34
0.
95
1.34
0.
23
1.08
0.
16
8.25
1.
59
6.62
1.
21
3.24
0.
44
2.58
0.
38
0.99
0.
18
0.79
0.
12
4.02
0.
62
3.12
0.
53
0.7
0.16
0.
56
0.09
x U
49.9
9 0.
35
1.42
0.
32
2.04
0.
39
13.3
8 1.
73
0.34
0.
07
13.9
5 0.
66
17.9
5 1.
16
0.51
0.
08
99.5
6
-
X
U
23.5
4.
71
0.17
0.
18
0.03
0.
033
0.07
7 0.
11
1.96
0.
64
0.19
0.
18
0.02
8 0.
019
24.6
4.
27
2 0.
63
8.36
2.
64
1.72
0.
5 10
.4
3.09
3.
89
1.11
1.
2 0.
27
4.96
1.
24
0.87
0.
17
37.2
11
.6
x 0
51.3
6 0.
65
1.35
0.
27
1.88
0.
39
8.62
1.
21
0.19
0.
05
15.4
2 1.
1 20
.81
0.27
0.
55
0.07
10
0.17
- X
I7
51.6
3.
83
0.26
0.
21
0.04
5 0.
036
0.03
6 0.
023
1.8
0.59
0.
6 0.
62
0.06
0.
049
19.6
5.
19
3.39
1.
06
12.6
3.
53
2.39
0.
65
13.2
3.
35
5.15
1.
11
1.63
0.
32
5.54
1.
22
32
11.2
- X
U
49.3
6 1.
24
1.74
0.
66
2.61
0.
77
13.4
9 2.
13
0.33
0.
12
14.2
2 1.
21
17.3
3 1.
59
0.43
0.
07
99.5
1
z U
33.8
5.
05
3.36
2.
33
0.02
td
48.2
18
.2
2.08
0.
89
0.86
0.
03
24.5
4.
26
2.05
1.
02
7.92
2.
66
1.68
0.
57
7.38
0.
83
5.28
2.
78
1.89
0.
92
4.27
0.
37
0.95
0.
21
0.88
0.
08
f U
1.41
0.
41
3 49
.55
1.04
F
3.18
1.
06
b 10
.62
1.81
5
15.2
5 0.
81
18.6
4 1.
07
3
0.49
0.
08
5
0.21
0.
09
3
99.3
4 P Q
2 3
30.3
5.
48
0
bdl
a
U
x 1.58
2.
73
0.02
8 0.
01
26.9
9.
09
b
1.58
0.
6
0.03
1
1.17
0.
3 5
5.39
1.
74
Fl 1.
13
0.34
6.
71
1.97
2.
77
0.7
1.03
0.
25
3.61
0.
9 0.
64
0.12
0.21
0.
1 2.
EY E. 9
17.8
Tabl
e 1
(con
tinue
d)
Are
a C
airo
-Sue
z El
Had
dadi
n E
l Had
dodi
n A
bu R
oash
El
Hel
uf
Zarr
ouk
Min
ya
Sam
ple
CSR
l K
32n
HA
D2
AR
Fl
H4
24
BN
N
o.
10/1
5 12
17
@I 1
I4
17
7/6
3640
5 9/
14
3 3. Dy
3.35
0.
53
4.27
0.
9 3.
34
0.58
5.
34
1.22
4.
82
1.19
4.
62
0.6
3.93
0.
88
g. Ho
0.67
0.
1 0.
87
0.15
0.
68
0.11
1.
05
0.22
0.
87
0.25
1.
01
0.08
0.
78
0.19
~
Er
1.81
0.
28
2.3
0.49
1.
79
0.38
2.
92
0.42
2.
07
0.52
2.
38
0.2
Tm
0.24
0.
03
0.31
0.
07
0.24
0.
07
0.4
0.07
0.
25
0.05
0.
43
0.16
0.
27
0.05
Y
b 1.
39
0.2
1.99
0.
47
1.47
0.
29
2.42
0.
47
1.4
0.4
1.94
0.
32
1.68
0.
38
5. Lu
0.21
0.
04
0.29
0.
06
0.23
0.
04
0.36
0.
07
0.2
0.07
0.
45
0.23
0.
24
0.07
-
sc
116
12
109
13
111
8 13
8 11
74
4
122
14
125
18
2 V
33
4 44
555
86
536
108
787
77
422
66
408
45
448
115
Ni
21
8 67
16
83
24
72
47
93
26
81
56
15
2.12
0.
5
Cr
40
40
161
88
547
386
52
56
70
42
372
236
81
g G
a 7.
68
1.67
6.
81
1.77
6.
06
1.18
9.
5 0.
9 9.
49
2.26
10
.4
1.12
11
.4
4.49
2 Q 3.
No.
: num
ber o
f ana
lyse
s (el
ectr
on m
icro
prob
efla
serp
robe
) exce
pt w
here
som
e las
erpr
obe a
nays
es w
ere
belo
w d
etec
tion limits as f
ollo
ws:
in CSRL, Ba, Th, U
and
Ta
aver
ages
refle
ct 9.
7,s
and
Maj
or el
emen
ts a
naly
sed
by e
lect
ron
mic
ropr
obe a
re re
port
ed as
oxid
es in w
t% w
ith to
tal i
ron as F
eO. T
race
ele
men
ts d
etec
ted
usin
g th
e la
serp
robe
are i
n pp
m.
bdl:
belo
w d
etec
tion
limit.
2 8analysesrespectively;HADZ,Ba,Th,Ta=3.7and7;ARFI,BqTh,UandTa=3,5,3and5;H4,TaandCr=4and2;ZA,Th,Hf,Ta,CrandNiall=l;BN,ThandTa=7and
10.
h)
w
W
234 L. M. Mallory-Greenough, J. D. Greenough, G. Dobosi and J. V. Owen
and rare earth element (REE, La to Lu; Table 1) concentrations decrease as percentages of mantle melting increase and the effects of mantle metasomatism (pre-magmatism fluid infiltration) decrease (Sun and Hanson 1975; Cullers et al. 1985). Said another way, concentra- tions of these elements are higher in alkaline magmas than in subalkaline magmas. Their concentrations in augite should reflect these variations because Henry’s Law for dilute solutions proposes that an element’s augite/magma concentration ratio (the partitioning coefficient) is very similar between different magmas (Wood and Fraser 1976, 193-202; Nielsen 1992).
Scandium, V and Ga show only modest variation between alkaline and subalkaline magmas (Pearce 1996). Siderophile element (e.g., Ni, Cr) concentrations are somewhat invariable between undifferentiated mafic magmas due to control by mantle olivine and pyroxene (Basaltic Volcanism Study Project 1981, 424). Thus variations in Ni reflect magma differentiation not mantle processes. Finally, Ti, Nb and Ta are lowered and Ba raised (relative to the REE) in a magma whose mantle source was affected by subduction (Fitton et al. 1991; Pearce 1996). After assessing the above, Sr, Zr, Nb, La, Sc, V and Ga were chosen for the cluster analysis (Fig. 2) though other combinations yielded analogous results.
Univariant F-tests (SYSTAT: Wilkinson et al. 1992) indicate that augite trace elements and major element oxides that strongly correlate ( p c 0.05) with regiodflow include (highest to lowest correlation) Sr, La, Ce, Ni, Pr, V, Nd, Sc, Sm, Eu, Gd, Tb, CaO, MnO, Ga, SO2, A1203, Nb, Cr, Zr, Ba, FeO, Yb, Hf, Dy, Lu, Y and Ho. From this group Sr, Zr, Nb, La, Sc, V and Ga were selected for discriminant analysis because they represent different geochemical groups. SYSTAT derived discriminant function equations which successfully classify 90% of augite analyses. The multivariate test statistics (Wilk’s Lambda, Pillai Trace, Hotelling-Lawley Trace, and Theta) are highly significant (pcO.OOOl), demonstrating the effectiveness of the selected elements for flow identification. Other element combinations work as well but adding elements to the seven selected results in a negligible increase in successful classification (-1% improvementlelement). Discriminant analysis by site yields similar results. However, samples of the same flow from different sites are so similar, and sample chemical variability at one site large enough that attempts to discriminate beyond region (i.e., to discriminate sites from one flow) are unwarranted.
Factor equations from the discriminant analysis (Table 2) yield the three sets of factors scores most useful for classifying the analyses (Fig. 3 (a) and (b)). These equations were also used for Figure 3 (c) and (d). Fields outlined in the quarry discrimination diagrams (Fig. 3 (a) and (b)) do not appear in the temper fragment plots (Fig. 3 (c) and (d)) due to scale changes. The scale difference confirms the cluster analysis conclusion that the quarries did not yield the temper fragments. An exception may be FKAX44 fragment 1 which falls in the Middle Egypt fields (Fig. 3 (a) and (b)).
Given that the augites in FKI5O temper fragments do not match the quarries they could have a local, unmapped Luxor source(s). Cluster analysis indicated that fragment augites are very different from one another. The discriminant analysis factor scores are also different from one another and the quarries (compare Fig. 3 (a)-(d)), suggesting that chemical variation reflects multiple sources rather than quarry heterogeneity.
Quarried stone was moved great distances in ancient Egypt (e.g., Chephren ‘diorite’; Franz et al. 1987). The FKAX44 analysis grouping with the middle Egyptian quarries (Fig. 2) may reflect the upstream movement of blocks from the closest, known, basalt quarry sites. Considering the common use of basalt in construction, statuary and sarcophagi, it would not
Fingetprinting ancienr Egyptian quarries 235
Table 2 Equaiions for calculaiing factor scores
Sr Zr Nb La sc V Ga Consiani
Augiie Factor 1 -0.091 0.007 1.191 -1.803 0.068 -0.009 0.297 -0.988 Factor 2 0.066 -0.047 -0.199 1.282 0.016 -0.014 0.469 -1.552 Factor 3 -0.116 -0.153 -0.485 2.719 0.032 -0.006 0.026 2.047
Factor scores for new augite analyses are calculated by multiplying the concentration of each element (ppm) by its coefficient, summing the products, and adding the constant (e.g., CSRl augite analysis, Table 1. Factor I = -0.091*23.34+0.007*17.28 + 1.191*0.11 - 1.803*0.96+0.068*116.14 -0.009*334.46+0.297*7.68 -0,988).
be surprising if waste material became pottery temper. Alternatively, -44 may have been manufactured in the Minya area before being transported to Luxor.
CONCLUSIONS
Based on microprobe data, most temper fragment mineral compositions overlap known Pharaonic quarries (Mallory-Greenough er al. in press). However, laserprobe trace element data indicate that temper fragment mineral compositions do not match known quarries. Apparently laserprobe trace element data are more useful for fingerprinting quarries than the major elements obtainable from the electron microprobe. The lack of compositional correspondence between most temper fragments and known quarries points to an unknown/ unrecognized quarry source(s). More detailed geological mapping may be required to identify such sources.
Given the undesirable effects of destructive analysis on valuable artefacts, the laserprobe’s small material requirements (thin sections or grain-mounts) and ability to determine simul- taneously numerous elements is important! However, grains < 20 p wide pose problems because sensitivity is proportional to the amount of mineral material vaporized. Limiting the number of elements detected increases the time available for counting each isotope but it also requires prior knowledge of those most useful for source identification. Useful elements may be identified by analysing quarry samples for a diverse group of elements using a wide laser beam. Then only elements useful for discrimination need be determined in the artefact. Alternatively, our results indicate that Sr, Zr, Nb, La, Sc, V and Ga are useful. Speculation on the fingerprinting ability of these elements in augites from non-Egyptian basalts should note that the majorhinor elements most useful for discriminating quarry sources (Ti02, MnO, Na20; Mallory-Greenough er al. in press) were also identified by Nisbet and Pearce (1977) as most suitable for basalt tectonic discrimination. Considering the geochemical and statistical basis on which the trace elements (Sr, Zr, Nb, etc.) were selected and their utility in whole-rock tectonic discrimination (Pearce 1996), it seems likely that they will prove useful in new situations. Nevertheless, there are monthly improvements in ICP-MS sensitivity. Thus, small beam sizes and comprehensive element lists are becoming less of a problem. The laserprobe should have a bright future in the determination of artefact provenance.
236 L. M. Mallory-Greenough, J. D. Greenough, G. Dobosi and J. V. Owen
c? 8 50 B
LL
0 -
-50
(Y
b B Y
-10 -5 0 5 Factor 1
-
-
d 200
100 (Y
b 2 Y
0
-100,
1 SHERDS FKl50 & FKAX44
0 X
A% FKl50 fragment 2 6 F W 4 4 3 V fragment 4 0 1 x 5 0 3 A Area of a]
%, 8 0 119 9 *
1 -150 -100 -50 0 I I I
Factor 1
2
1 0
Y d o - 1
-2
-3
-4 -10 -5 0 5
Factor 1
150
1 W t O
x A * Area of b) I
A
0 A o * * *
-100' I 1 8 I -200 -150 -100 -50 0 50
Factor 1 Figure 3 Discriminant analysis of quarry augites based on region (a) and (b) and application to the majc temper fragments (c) and (d). Symbols for (b) appear in (a) and those for (d) in (c). Fields in (a) and (b) were added by hand with labels rejecting the dominant (> 80% of ahta) region. FKISO and F M 4 4 temper fragments were plotted (c), (d) using scores from Table 1 factor equations. Region labels could not be added due to scale differences, bur areas encompassed by (a) and (b) appear as bold squares (c) and (d). Elements used in the discriminant functions are given in the text.
ACKNOWLEDGEMENTS
Dr D. B. Redford (Akhenaten Temple Project) supplied pottery and advice. R. Hummel and G. Mumford aided in pottery selection. Preparation at University of Windsor was courtesy of B. J. Fryer. A. Madani supplied rocks. R. MacKay helped with the microprobe at Dalhousie University. LAM-ICP-MS analyses were performed at Memorial University of Newfoundland with advice from S. Jackson and H. Longerich. H. Muggeridge helped with diagrams. K. Tymchuk worked on tables. D. Hattie provided references. J. D. G. and J. V. 0. acknowledge NSERC grants.
Fingerprinting ancient Egyptian quarries 237
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