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Trace-element analysis of Mayan obsidian blades from Yucatan and Campeche Provinces, Mexico
ChemicalGeology, 88 (1990) 163-167 Elsevier Science Publishers B.V., Amsterdam
163
[7]
Trace-element analysis of Mayan obsidian blades from Yucatan and Campeche Provinces, Mexico Peter S. Dahl a, Barbara M. Harkness b and Garry C. Maurath a aDepartment of Geology, Kent State University, Kent, OH 44242 (U.S.A.) bDepartment of Sociology and Anthropology, Kent State University, Kent, OH 44242 (U.S.A.) (Received December 1, 1987; revised and accepted May ! 5, 1990 )
ABSTRACT Dahl, P.S., Harkness, B.M. and Maurath, G.C., 1990. Trace-element analysis of Mayan obsidian blades from Yucatan and Campeche Provinces, Mexico. Chem. Geol., 88: 163-167. Nine Mayan obsidian knife blades from two Late Classic (i.e. 700-900 A.D. ) sites in the Yucatan Peninsula, Mexico, have been analyzed by inductively coupled plasma emission spectroscopy (ICPES) for the elements Ca, Fe, K, Ba, La, Mn, Sr, Ti, Zn and Zr; Rb was analyzed by atomic absorption spectrophotometry. These data permit unique assignment of a volcanic obsidian source for each artifact. Obsidian for five of the blades originated from the Pachuca and Zinapecuaro-Ucareo localities near present-day Mexico City; obsidian for the other four was derived from E1Chayal, a locality near present-day Guatemala City, Guatemala. These results indicate that extensive trade and supply networks existed during Late Classic times. From purely an analytical standpoint, these results demonstrate that ICPES is a potentially valuable tool in geo-archaeological studies.
I. Introduction
In the last two decades, chemical compositions of obsidian artifacts have proven highly useful to geo-archaeologists seeking to reconstruct the nature of ancient Mayan supply routes and trade networks in Mesoamerica. The standard technique has been first to analyze the artifacts for selected trace metals, either by neutron activation (NAA) or X-ray fluorescence ( X R F ) analysis, and then to compare the results to well-documented tracemetal contents of known volcanic obsidian outcrops in Mesoamerica (e.g., Stross et al., 1983 ). This chemical fingerprinting approach permits assignment of the artifact to a particular source. By now, the collective artifact "sourcing" of many investigators, combined with radiocarbon dating of strata, has enabled geo-archaeologists to glimpse a much clearer 0009-2541/90/$03.50
picture of Mayan history than they could otherwise have obtained. Until now, inductively coupled plasma emission spectroscopy (ICPES) has not been employed in geo-archaeological studies. Our principal purpose in this paper, therefore, is to describe what we believe is the first such application of ICPES, and thereby demonstrate its general applicability to geo-archaeological studies. Specifically, we first present chemical analyses of nine obsidian knife blades, then show how these analyses are used to infer original source localities of the obsidian. Details of the interpretations of our results will be presented elsewhere (B.M. Harkness et al., in prep.). The nine Mayan knife blades included in this study are from two Late Classic (i.e. 700-900 A.D. ) sites in the Yucatan Peninsula, Mexico. One site, known as Hochub, is located in the
© 1990 - - Elsevier Science Publishers B.V.
P.S. DAHLET AL
164 TABLE I
2. Experimental
Analytical parameters Element
Each knife blade was first soaked in 20% HC1 for 0.5 hr to remove surface metallic contamination, then ~0.4 g was trimmed off with a trim saw and powdered to 100-170 mesh in an agate mortar. A portion of each powder (0.25 g) was then dissolved in 25 ml of 8% HC1, following standard HF-HC104 digestion, as described by Thompson and Walsh ( 1983 ). Reagent grade acids were used in each step of the procedure. Calibration of the ICP spectrometer was performed using U.S.G.S. standard granite G-2, which represented a close matrix match to the obsidian samples. The standard was digested at 80°C in HF-HC104 overnight prior to acid evaporation to maximize dissolution of any zircon contained therein. Nearly quantitative recovery of Zr ( ~ 99%) was verified by comparison of Zr emission to that of an aqueous Zr standard. Obsidian being volcanic glass, it does not contain the mineral zircon, so extra digestion of the samples was not required in order to achieve quantitative Zr recovery. Except for Rb, all elements were analyzed on
Wavelength
(nm) Sr Zr Mn Ba La Fe Zn Ti Ca K
407.77 343.82 257.61 455.50 379.48 238.20 206.20 336.12 317.93 769.90
Sample delivery Torch height Integration time Radiofrequency (RF) power Sample Ar Coolant Ar
1 ml min.14 mm 1-3 s 1,200 W 0.75 1min.131 rain.-
southernmost part of Yucatan Province; the other site, Chunhuhub, is in Campeche Province, ~ 65 km south of the present-day Gulfcoastal town of Campeche. TABLE II
Abundances of selected major and trace elements in Mayan obsidian blades from Yucatan and Campeche Provinces, Mexico Sample number *~ H-1 K20 (wt.%) Fe203,3 CaO TiO2 MnO Ba (ppm) Sr Rb Zr Zn La
3.91 0.86 0.98 0.148 0.985 940 136 142 76 22 29
H-2 4.66 1.12 0.50 0.089 0.022 163 13 143 87 16 39
H-3 4.53 0.91 1.01 0.151 0.089 970 149 142 77 19 31
C-4 5.54 2.40 0.I1 0.217 0.155 18 3.1 200 774 254 81
C-5 4.32 2.45 0.12 0.209 0.154 20 3.2 199 762 250 81
C-6 4.80 1.03 0.46 0.062 0.026 33 5.4 185 73 22 40
C-7 4.53 0.88 0.97 0.150 0.087 922 145 140 76 22 33
C-8 .2 4.07_+0.37 2.40 _+0.04 0.11 - + 0 . 0 0 0.208_+0.005 0.152_+0.004 16_+3 2.4_+0.1 191_+3 798_+ 12 249_+ 1 87_+2
C - 9 .2
4.23_+0.10 0.93 _+0.02 0.965_+0.007 0.148+0.002 0.152_+0.001 905_+ 11 142_+ 3 139_+5 74_+2 194_+4 43_+3
*~Prefixes H and C designate Hochub and Chunhuhub localities, respectively. *2precision values ( _+1a) reflect random errors in sample preparation and analytical measurement. Values are comparable for other samples. *3Total iron reported as Fe203.
TRACE-ELEMENT ANALYSIS OF OBSIDIAN FROM YUCATAN AND CAMPECHE
an Allied Analytical Systems ® Plasma 200 ICP spectrometer; instrumental operating parameters and analytical wavelengths are summarized in Table I. Rb was analyzed on a PerkinElmer ® model 4 0 3 A A A S unit. For each element, background and analyte drift corrections were performed by an H P - 2 0 0 ® microcomputer. Background drift correction involved subtraction of the adjacent blank analysis from each sample analysis. Correction of minor analyte drift was performed, for each element, by applying a standard-based regression function of percent error (blank-corrected) vs. time to the raw sample data. Two samples (C-8 and C-9) were prepared and analyzed in duplicate as a check on precision of the analytical procedures. All analytical resuits are summarized in Table II. In our laboratory, previous analytical intercorrelations among U.S.G.S. silicate rock standards and among aqueous standards have shown, for the levels of major and trace elements indicated in Table II, that accuracies within _+2% and + 5%, respectively, of accepted values (from Abbey, 1983), are routinely obtained. These figures are taken as an indication of accuracy for the data in Table II. 3. Results and discussion
Reliable "sourcing" of obsidian artifacts by chemical fingerprinting operates on the premise that trace-element variation is relatively limited within any one volcanic obsidian source and, further, that it is much greater between sources than within sources (Zeitlin and Heimbuch, 1978, p. 120). Justification for this premise is shown in Fig. l, in which the twelve most important Mayan obsidian sources are well separated in Zr-Sr-Rb, M n - T i - F e and M n - T i - B a compositional space. However, other three-element diagrams fail to discriminate sources. The circular and elliptical fields in Fig. 1 represent the known intra-source variability (Nelson et al., 1977, 1983) as determined by NAA and X R F of multiple obsidians
16 5
from each source. Locations of the twelve sources shown in Fig. 1 and other selected sources of obsidian in Mesoamerica are given by Nelson et al. ( 1983, fig. 169, p. 204). Superimposed in Fig. I are the compositions of the nine artifacts included in this study, with the inferred source(s) for each artifact indicated adjacent to each diagram. The Pachuca locality is unique in that it is the only known source of green obsidian in Mesoamerica. Samples 4, 5 and 8 (Table II) are green in color, thus indicating Pachuca as their source. The Zr and Ba diagrams corroborate this conclusion, thereby indicating a high degree of accuracy for the Zr, Rb, Mn and Ti analyses of these samples. In the Fe diagram, however, these samples do not plot in the Pachuca field; instead, they plot very close to the Jalapa, Tajumulco and Pachuca fields. Had the measured Fe content of these control samples been slightly higher they would have plotted in the Pachuca field as expected. Perhaps such slight discrepancies between analytical methods are inevitable. Alternatively, the samples are not representative of the obsidian populations used to characterize the different sources. Given these potential difficulties, it is evident that a single diagram is insufficient to source a given artifact uniquely. Instead, the three diagrams must be considered together to infer a consensus source. This approach yields Pachuca (in Hildalgo, Mexico); E1 Chayal (in Guatemala); and Zinapecuaro-Ucareo (in Michoacan, Mexico) as the consensus obsidian sources for samples 4, 5 and 8; I, 3, 7 and 9; and 2 and 6, respectively. The Pachuca and Zinapecuaro-Ucareo obsidian sources are ~ 1000 km west of the Yucatan artifact sites, and the E1 Chayal source is ~ 650 km south of these sites. These distances probably represent minimum estimates of the extent of trade routes or supply networks between 700 and 900 A.D. The magnitude of these distances is rather remarkable in light of two facts: the ancient Mayans, for all their accomplishments, never invented the wheel for
166
P.S. DAHL ET A L
WT% T I 0 2
PPM SR /
~
SAMPLENO •
/
\
P:SSIBLE SOURCE(S)
•
SAMPLENOra 1379
POSSIBLESOURCE(S) A,D,E
"
4,5,8
F,B,C
I,3,7,9
..,o.s
F
/
x~
G
PPM ZR
G
PPM RB
WT% MNO
SAMPLE NO
POSSIBLE SOURCEISI
WT%
PPM TI02
OBSIDIAN SOURCE(COUNTRY)
\
• 1,3,7,9
A,B,C
=,.,.B
F
&s
G,H G,J,K
PPM MNO
FE205-:-IO
A B
EL CHAYAL (GUATEMALA) JALAPA (GUATEMALA)
C D E F
TAJUMULCO(GUATEMALA) SAN MARTIN JILOTEPEQUE(GUATEMALA) TAJUMULCO-SANLORENZO(GUATEMALA) PACHUCA(MEXICO)
G
ZINAPECUARO-UCAREO(MEXICO)
H
PAREDON(MEXICO)
J
ZACUALTIPAN(MEXICO)
K
CRUZ DE APAN (GUATEMALA)
L
IXTEPEQUE (GUATEMALA)
M
OTUMBA (MEXICO)
PPM BA
Fig. 1. Discriminant diagrams showing chemical variations among the twelve major geologic sources of obsidian in Mesoamerica. Superimposed on the diagrams are data points representing the nine obsidian knife blades of this study. Precise locations of these sources are given in Nelson et al. ( 1983, p. 204).
transportation, nor did they have beasts of burden. However, according to Miller ( 1977 ), the Mayans were excellent sailors, so it is likely that, in addition to human porterage, the sailboat was an important means of transport for goods such as obsidian. 4. Conclusions Two main conclusions arise from this study: ( 1 ) ICPES is a viable method for rapid source determination of obsidian artifacts; and (2) the Yucatan artifacts analyzed in this study derived from volcanic obsidian outcrops near
present-day Mexico City, Mexico, and Guatemala City, Guatemala. References Abbey, S., 1983. Studies in "standard samples" of silicate rocks and minerals, 1969-1982. Geol. Sur. Can., Pap. 83-15, 114 pp. Miller, A.G., 1977. The Maya and the sea: Trade and cult at Tancah and Tulum, Quintana Roo. In: E.P. Benson (Editor), The Sea in the pre-Columbian World, Washington, D.C., pp. 97-135. Nelson, F.W., Neilson, K., Mangelson, N., Hill, M.W. and Matheny, R.T., 1977. Preliminary studies of the traceelement composition of obsidian artifacts from northern Campeche, Mexico. Am. Antiq., 42(2): 209-225.
TRACE-ELEMENTANALYSISOF OBSIDIANFROMYUCATANANDCAMPECHE Nelson, F.W., Phillips, D.A. and Rubio, A.B., 1983. Trace element analysis of obsidian artifacts from the northern Maya lowlands. Pap. New Archaeol. World Found. (Brigham Young Univ.), 56: 204-239. Stross, F., Sheets, P., Asaro, F. and Michel, H.V., 1983. Precise characterization of Guatemalan obsidian sources, and source determination of artifacts from Quirig6a. Am. Antiq., 48(2): 323-346.
167
Thompson, M. and Walsh, J., 1983. A Handbook of Inductively Coupled Plasma Spectrometry. Blackie, Glasgow, 273 pp. Zeitlin, R.N. and Heimbuch, R.C., 1978. Trace element analysis and the archaeological study of obsidian procurement in pre-Columbian Mesoamerica: Lithics and substinence. Vanderbilt Univ. Publ. Anthropol., Nashville, Tenn., 20:117-159.
163
[7]
Trace-element analysis of Mayan obsidian blades from Yucatan and Campeche Provinces, Mexico Peter S. Dahl a, Barbara M. Harkness b and Garry C. Maurath a aDepartment of Geology, Kent State University, Kent, OH 44242 (U.S.A.) bDepartment of Sociology and Anthropology, Kent State University, Kent, OH 44242 (U.S.A.) (Received December 1, 1987; revised and accepted May ! 5, 1990 )
ABSTRACT Dahl, P.S., Harkness, B.M. and Maurath, G.C., 1990. Trace-element analysis of Mayan obsidian blades from Yucatan and Campeche Provinces, Mexico. Chem. Geol., 88: 163-167. Nine Mayan obsidian knife blades from two Late Classic (i.e. 700-900 A.D. ) sites in the Yucatan Peninsula, Mexico, have been analyzed by inductively coupled plasma emission spectroscopy (ICPES) for the elements Ca, Fe, K, Ba, La, Mn, Sr, Ti, Zn and Zr; Rb was analyzed by atomic absorption spectrophotometry. These data permit unique assignment of a volcanic obsidian source for each artifact. Obsidian for five of the blades originated from the Pachuca and Zinapecuaro-Ucareo localities near present-day Mexico City; obsidian for the other four was derived from E1Chayal, a locality near present-day Guatemala City, Guatemala. These results indicate that extensive trade and supply networks existed during Late Classic times. From purely an analytical standpoint, these results demonstrate that ICPES is a potentially valuable tool in geo-archaeological studies.
I. Introduction
In the last two decades, chemical compositions of obsidian artifacts have proven highly useful to geo-archaeologists seeking to reconstruct the nature of ancient Mayan supply routes and trade networks in Mesoamerica. The standard technique has been first to analyze the artifacts for selected trace metals, either by neutron activation (NAA) or X-ray fluorescence ( X R F ) analysis, and then to compare the results to well-documented tracemetal contents of known volcanic obsidian outcrops in Mesoamerica (e.g., Stross et al., 1983 ). This chemical fingerprinting approach permits assignment of the artifact to a particular source. By now, the collective artifact "sourcing" of many investigators, combined with radiocarbon dating of strata, has enabled geo-archaeologists to glimpse a much clearer 0009-2541/90/$03.50
picture of Mayan history than they could otherwise have obtained. Until now, inductively coupled plasma emission spectroscopy (ICPES) has not been employed in geo-archaeological studies. Our principal purpose in this paper, therefore, is to describe what we believe is the first such application of ICPES, and thereby demonstrate its general applicability to geo-archaeological studies. Specifically, we first present chemical analyses of nine obsidian knife blades, then show how these analyses are used to infer original source localities of the obsidian. Details of the interpretations of our results will be presented elsewhere (B.M. Harkness et al., in prep.). The nine Mayan knife blades included in this study are from two Late Classic (i.e. 700-900 A.D. ) sites in the Yucatan Peninsula, Mexico. One site, known as Hochub, is located in the
© 1990 - - Elsevier Science Publishers B.V.
P.S. DAHLET AL
164 TABLE I
2. Experimental
Analytical parameters Element
Each knife blade was first soaked in 20% HC1 for 0.5 hr to remove surface metallic contamination, then ~0.4 g was trimmed off with a trim saw and powdered to 100-170 mesh in an agate mortar. A portion of each powder (0.25 g) was then dissolved in 25 ml of 8% HC1, following standard HF-HC104 digestion, as described by Thompson and Walsh ( 1983 ). Reagent grade acids were used in each step of the procedure. Calibration of the ICP spectrometer was performed using U.S.G.S. standard granite G-2, which represented a close matrix match to the obsidian samples. The standard was digested at 80°C in HF-HC104 overnight prior to acid evaporation to maximize dissolution of any zircon contained therein. Nearly quantitative recovery of Zr ( ~ 99%) was verified by comparison of Zr emission to that of an aqueous Zr standard. Obsidian being volcanic glass, it does not contain the mineral zircon, so extra digestion of the samples was not required in order to achieve quantitative Zr recovery. Except for Rb, all elements were analyzed on
Wavelength
(nm) Sr Zr Mn Ba La Fe Zn Ti Ca K
407.77 343.82 257.61 455.50 379.48 238.20 206.20 336.12 317.93 769.90
Sample delivery Torch height Integration time Radiofrequency (RF) power Sample Ar Coolant Ar
1 ml min.14 mm 1-3 s 1,200 W 0.75 1min.131 rain.-
southernmost part of Yucatan Province; the other site, Chunhuhub, is in Campeche Province, ~ 65 km south of the present-day Gulfcoastal town of Campeche. TABLE II
Abundances of selected major and trace elements in Mayan obsidian blades from Yucatan and Campeche Provinces, Mexico Sample number *~ H-1 K20 (wt.%) Fe203,3 CaO TiO2 MnO Ba (ppm) Sr Rb Zr Zn La
3.91 0.86 0.98 0.148 0.985 940 136 142 76 22 29
H-2 4.66 1.12 0.50 0.089 0.022 163 13 143 87 16 39
H-3 4.53 0.91 1.01 0.151 0.089 970 149 142 77 19 31
C-4 5.54 2.40 0.I1 0.217 0.155 18 3.1 200 774 254 81
C-5 4.32 2.45 0.12 0.209 0.154 20 3.2 199 762 250 81
C-6 4.80 1.03 0.46 0.062 0.026 33 5.4 185 73 22 40
C-7 4.53 0.88 0.97 0.150 0.087 922 145 140 76 22 33
C-8 .2 4.07_+0.37 2.40 _+0.04 0.11 - + 0 . 0 0 0.208_+0.005 0.152_+0.004 16_+3 2.4_+0.1 191_+3 798_+ 12 249_+ 1 87_+2
C - 9 .2
4.23_+0.10 0.93 _+0.02 0.965_+0.007 0.148+0.002 0.152_+0.001 905_+ 11 142_+ 3 139_+5 74_+2 194_+4 43_+3
*~Prefixes H and C designate Hochub and Chunhuhub localities, respectively. *2precision values ( _+1a) reflect random errors in sample preparation and analytical measurement. Values are comparable for other samples. *3Total iron reported as Fe203.
TRACE-ELEMENT ANALYSIS OF OBSIDIAN FROM YUCATAN AND CAMPECHE
an Allied Analytical Systems ® Plasma 200 ICP spectrometer; instrumental operating parameters and analytical wavelengths are summarized in Table I. Rb was analyzed on a PerkinElmer ® model 4 0 3 A A A S unit. For each element, background and analyte drift corrections were performed by an H P - 2 0 0 ® microcomputer. Background drift correction involved subtraction of the adjacent blank analysis from each sample analysis. Correction of minor analyte drift was performed, for each element, by applying a standard-based regression function of percent error (blank-corrected) vs. time to the raw sample data. Two samples (C-8 and C-9) were prepared and analyzed in duplicate as a check on precision of the analytical procedures. All analytical resuits are summarized in Table II. In our laboratory, previous analytical intercorrelations among U.S.G.S. silicate rock standards and among aqueous standards have shown, for the levels of major and trace elements indicated in Table II, that accuracies within _+2% and + 5%, respectively, of accepted values (from Abbey, 1983), are routinely obtained. These figures are taken as an indication of accuracy for the data in Table II. 3. Results and discussion
Reliable "sourcing" of obsidian artifacts by chemical fingerprinting operates on the premise that trace-element variation is relatively limited within any one volcanic obsidian source and, further, that it is much greater between sources than within sources (Zeitlin and Heimbuch, 1978, p. 120). Justification for this premise is shown in Fig. l, in which the twelve most important Mayan obsidian sources are well separated in Zr-Sr-Rb, M n - T i - F e and M n - T i - B a compositional space. However, other three-element diagrams fail to discriminate sources. The circular and elliptical fields in Fig. 1 represent the known intra-source variability (Nelson et al., 1977, 1983) as determined by NAA and X R F of multiple obsidians
16 5
from each source. Locations of the twelve sources shown in Fig. 1 and other selected sources of obsidian in Mesoamerica are given by Nelson et al. ( 1983, fig. 169, p. 204). Superimposed in Fig. I are the compositions of the nine artifacts included in this study, with the inferred source(s) for each artifact indicated adjacent to each diagram. The Pachuca locality is unique in that it is the only known source of green obsidian in Mesoamerica. Samples 4, 5 and 8 (Table II) are green in color, thus indicating Pachuca as their source. The Zr and Ba diagrams corroborate this conclusion, thereby indicating a high degree of accuracy for the Zr, Rb, Mn and Ti analyses of these samples. In the Fe diagram, however, these samples do not plot in the Pachuca field; instead, they plot very close to the Jalapa, Tajumulco and Pachuca fields. Had the measured Fe content of these control samples been slightly higher they would have plotted in the Pachuca field as expected. Perhaps such slight discrepancies between analytical methods are inevitable. Alternatively, the samples are not representative of the obsidian populations used to characterize the different sources. Given these potential difficulties, it is evident that a single diagram is insufficient to source a given artifact uniquely. Instead, the three diagrams must be considered together to infer a consensus source. This approach yields Pachuca (in Hildalgo, Mexico); E1 Chayal (in Guatemala); and Zinapecuaro-Ucareo (in Michoacan, Mexico) as the consensus obsidian sources for samples 4, 5 and 8; I, 3, 7 and 9; and 2 and 6, respectively. The Pachuca and Zinapecuaro-Ucareo obsidian sources are ~ 1000 km west of the Yucatan artifact sites, and the E1 Chayal source is ~ 650 km south of these sites. These distances probably represent minimum estimates of the extent of trade routes or supply networks between 700 and 900 A.D. The magnitude of these distances is rather remarkable in light of two facts: the ancient Mayans, for all their accomplishments, never invented the wheel for
166
P.S. DAHL ET A L
WT% T I 0 2
PPM SR /
~
SAMPLENO •
/
\
P:SSIBLE SOURCE(S)
•
SAMPLENOra 1379
POSSIBLESOURCE(S) A,D,E
"
4,5,8
F,B,C
I,3,7,9
..,o.s
F
/
x~
G
PPM ZR
G
PPM RB
WT% MNO
SAMPLE NO
POSSIBLE SOURCEISI
WT%
PPM TI02
OBSIDIAN SOURCE(COUNTRY)
\
• 1,3,7,9
A,B,C
=,.,.B
F
&s
G,H G,J,K
PPM MNO
FE205-:-IO
A B
EL CHAYAL (GUATEMALA) JALAPA (GUATEMALA)
C D E F
TAJUMULCO(GUATEMALA) SAN MARTIN JILOTEPEQUE(GUATEMALA) TAJUMULCO-SANLORENZO(GUATEMALA) PACHUCA(MEXICO)
G
ZINAPECUARO-UCAREO(MEXICO)
H
PAREDON(MEXICO)
J
ZACUALTIPAN(MEXICO)
K
CRUZ DE APAN (GUATEMALA)
L
IXTEPEQUE (GUATEMALA)
M
OTUMBA (MEXICO)
PPM BA
Fig. 1. Discriminant diagrams showing chemical variations among the twelve major geologic sources of obsidian in Mesoamerica. Superimposed on the diagrams are data points representing the nine obsidian knife blades of this study. Precise locations of these sources are given in Nelson et al. ( 1983, p. 204).
transportation, nor did they have beasts of burden. However, according to Miller ( 1977 ), the Mayans were excellent sailors, so it is likely that, in addition to human porterage, the sailboat was an important means of transport for goods such as obsidian. 4. Conclusions Two main conclusions arise from this study: ( 1 ) ICPES is a viable method for rapid source determination of obsidian artifacts; and (2) the Yucatan artifacts analyzed in this study derived from volcanic obsidian outcrops near
present-day Mexico City, Mexico, and Guatemala City, Guatemala. References Abbey, S., 1983. Studies in "standard samples" of silicate rocks and minerals, 1969-1982. Geol. Sur. Can., Pap. 83-15, 114 pp. Miller, A.G., 1977. The Maya and the sea: Trade and cult at Tancah and Tulum, Quintana Roo. In: E.P. Benson (Editor), The Sea in the pre-Columbian World, Washington, D.C., pp. 97-135. Nelson, F.W., Neilson, K., Mangelson, N., Hill, M.W. and Matheny, R.T., 1977. Preliminary studies of the traceelement composition of obsidian artifacts from northern Campeche, Mexico. Am. Antiq., 42(2): 209-225.
TRACE-ELEMENTANALYSISOF OBSIDIANFROMYUCATANANDCAMPECHE Nelson, F.W., Phillips, D.A. and Rubio, A.B., 1983. Trace element analysis of obsidian artifacts from the northern Maya lowlands. Pap. New Archaeol. World Found. (Brigham Young Univ.), 56: 204-239. Stross, F., Sheets, P., Asaro, F. and Michel, H.V., 1983. Precise characterization of Guatemalan obsidian sources, and source determination of artifacts from Quirig6a. Am. Antiq., 48(2): 323-346.
167
Thompson, M. and Walsh, J., 1983. A Handbook of Inductively Coupled Plasma Spectrometry. Blackie, Glasgow, 273 pp. Zeitlin, R.N. and Heimbuch, R.C., 1978. Trace element analysis and the archaeological study of obsidian procurement in pre-Columbian Mesoamerica: Lithics and substinence. Vanderbilt Univ. Publ. Anthropol., Nashville, Tenn., 20:117-159.