Characterizing the micromorphology and chemistry of
sediments associated with Chinchorro mortuary
materials using SEM, EDS, and XRD
John G. Van Hoesen and Bernardo Arriaza
Green Mountain College
Instituto de Alta Investigación
Outline
• Background
• Methods
• Results
• Discussion
• Future Work
Arriaza, 2008
1
Background
1.0
1. Quebrada Jaquay
2.
Ring Site
3.
Quebrada Tachuay
4.
Los Burros
5.
Acha and Chinchorro
6.
Camarones
7.
Punta Pichalo
8.
Tiliviche and Aragón
9.
Patillo
10. Los Conchas
N
Santoro et al. 2005
2
Background
2.0
QUESTIONS
•
Do cavity sediments & face masks have a unique geochemical
signature?
•
Where did the Chinchorro source mortuary materials?
•
How mobile were Chinchorro relative to their coastal occupation sites?
N
Methodology
• XRD, SEM, EDS
• Cavity sediment (7 samples)
• Clay face mask (5 samples)
• Field sediment (7 samples)
Arriaza, 2008
3
Vitor
Perfil Melus
Cancha de Tiro
4
Results
1.0
SEM & EDS – cavity sediments
Indicates sediment is primarily composed of quartz, halite, gypsum, clay and muscovite.
Equidimensional, well-rounded
quartz grains lacking visible cement
Results
Abraded quartz grains coated
with pedogenic argillans
2.0
SEM & EDS – cavity sediments
C
H
H
C
Subhedral halite crystal exhibiting
evidence of dissolution surrounded
by clay minerals
Anhedral, amorphous gypsum
exhibiting evidence of dissolution
5
Results
3.0
SEM & EDS – cavity sediments
H
Anhedral, amorphous gypsum with
relict cleavage
Results
EDS spectra indicating presence of
Na, Cl, and Au
4.0
SEM & EDS – cavity sediments
C
C
C
C
G
G
G
C
C
Euhedral, lenticular gypsum crystal
Euhedral, tabular gypsum crystals
surrounded by clay.
6
Results
5.0
SEM & EDS – cavity sediments
Organic fibers from reeds used in
mortuary preparation
Results
Honeycomb texture associated with
reeds
6.0
XRD – cavity sediments
Indicates sediment is primarily composed of quartz (30%), albite (26%), sanidine (15%)
muscovite (12%) and a variety of accessory minerals (17%).
Halita
Mordenita 2%
1%
Beidellita
4%
Heulandita
1%
Otros
4%
Cuarzo
30%
Moscovita
5%
Cuarzo
Albita
Sanidina
Moscovita
Moscovita
12%
Moscovita
Beidellita
Mordenita
Sanidina
15%
Halita
Albita
26%
Heulandita
Otros
Average values for minerals identified using XRD
7
M1T1C6
M1T1C7
Maderas
Enco C1
Maderas
Enco C2
Maestranza
Chinchorro
C2
Maestranza
Chinchorro
C4
PLM8
Cr01
Cuarzo (SiO2)
30,32
33,81
22,62
32,07
30,88
27,6
34,56
Albita[NaSi3AlO8]
19,02
26,04
27,42
28,97
10,88
Especies Minerales (% en peso)
27,06
29,87
20,23
Sanidina (Na0,56K3,44Al4Si12O32)
14,59
13,66
15,41
16,03
14,37
22,65
Moscovita [KAl2Si3AlO10(OH)2]
11,07
8,99
-
18,21
20,92
16,03
-
-
-
19,69
-
-
-
16,4
Beidellita (arcilla, grupo Smectita) [Na0,3Al2(Si,Al)4O10(OH)2x2H2O]
10,1
3,8
6,6
6,3
1,7
1,1
2,4
Mordenita (zeolita) [Ca 0,40Al0,98Si5,03O12(H2O)3]
5,19
-
-
3,87
-
-
-
Clorita [(Mg,Fe)6(Si,Al)4O10(OH)8]
1,54
-
-
-
-
-
-
Clorita [(Mg5Al)(Si,Al)4O10(OH)8]
-
1,39
-
-
-
-
-
0,13
-
-
-
-
-
-
Actinolita [Ca2(Mg,Fe)5Si8O22(OH)]
-
-
-
-
-
-
0,44
Vermiculita (arcilla) [Mg3Si4O10(OH)2]
-
-
-
3,6
-
-
-
Montmorillonita (arcilla, grupo Smectita) [Na0,3(Al,Mg)2Si4O10(OH)2x8H2O]
-
-
7,5
-
-
-
-
Montmorillonita (arcilla, grupo Smectita) [Na0,3(Al,Mg)2Si4O10(OH)2x6H2O]
-
-
5,3
-
-
-
-
Yeso (CaSO4x2H2O)
-
-
0,96
-
-
-
0,53
Nitratina (NaNO3)
-
1,53
0,92
-
-
1,41
-
Hematita (Fe2O3)
-
0,5
0,77
0,44
-
-
0,83
Halita (NaCl)
-
6,45
-
0,43
1,59
-
1,79
Heulandita (zeolita) [Ca(Si7Al2)O18x6H2O]
-
-
-
-
3,5
3,79
1,81
Caolinita (arcilla, grupo Caolinita) [Al2Si2O5(OH)4]
-
-
-
-
1
-
0,64
Calcita (CaCO3)
-
-
-
-
-
-
0,74
Dolomita [CaMg(CO3)2]
-
-
-
0,03
-
-
-
Moscovita [(K,Na)Al2(Si,Al)4O10(OH,F)2]
Actinolita [Na0,08Ca1,76Mn0,16Mg1,88Fe2,72Fe0,32Al0,32Si7,68O22(OH)2]
Results
7.0
SEM & EDS – clay face masks
Indicates mask is primarily composed of manganese coating a thin layer of clay.
Cross section along edge of
clay mask
8
Results
7.0
SEM & EDS – clay face masks
Indicates mask is primarily composed of manganese coating a thin layer of clay.
Element
Cross section along edge of
clay mask (internal side facing)
Results
Weight%
Atomic%
Compd%
Formula
Na K
0.61
1.45
0.83
Na2O
Al K
0.45
0.91
0.86
Al2O3
Si K
1.86
3.60
3.99
SiO2
Cl K
0.75
1.14
0.00
KK
2.92
4.05
3.52
K2O
Ca K
1.11
1.51
1.56
CaO
Mn K
30.91
30.52
39.91
MnO
Fe K
6.93
6.73
8.92
FeO
O
14.77
50.08
7.0
XRD – clay face masks
Indicates sub-equal amounts of psilomelane and pyrolusite, and possibly rhodochrosite.
Psilomelane
(Ba,H2O) 2Mn5O10
Pyrolusite
MnO2
Rhodochrosite
MnCO2
?
?
Braunite
Mn2+Mn3+6SiO12
Piedmontite
?
Ca2Al1.8Mn2+0.9Fe2+0.3(SiO4)3(OH)
9
Discussion
1.0
XRD – cavity sediments
Significance of biedelite, montmorillionite, mordenite, heulandite
• Smectites associated with local bentonites
• Expansive clays aids plasticity of clay
• Geochemical signature different from identified clay sources
• Zeolites = “La Roca Magica”
(Bascuñan et al. 2007; Utada, 2001; Mumpton, 1999; Levy et al. 1989)
• Desiccant properties (Virta, 1997; PAHO, 2004)
• Pet litter and odor control
• Embalming techniques for body fragments
Discussion
2.0
SEM & EDS – clay face masks
Significance of high Mn content
• High graded material = large source
• Significance in mortuary process?
• Geochemical signature for sourcing
• Currently indicative of greater travel distances
• ~ 40km inland travel (Núñez, 1983; Núñez and Zlatar, 1980)
• No local source for Mn
10
Discussion
3.0
XRD – clay face mask
Significance of manganese minerals
• Geochemistry of Mn minerals should help isolate source
• Soil nodules (Sanz et al. 1996)
• Marine nodules (Achurra et al. 2009; Somayajulu, 2000)
• Ore deposits
• Local Candidates?
} • Psiliomelane ~90km from Arica (
• Huaylas Formation ~80-140km east of Arica (Garcia et al. 1996; Ossa, 1970)
Hewitt and Olivares, 1962)
• Fluvial transport by Rio Lluta & Rio San José? (Zeilinger et al. 2005)
• Los Pumas Manganese Project ~ 170km from Arica?
• Oxygen isotopes (Mandernack et al. 1995)?
Potential Mn
~80-90km
40km buffer
from coastal
sites
Geologic Map of Arica (SERNGEOMIN, 2002)
11
Zeilinger et al. 2005
Future Work
• Collect and analyze clay and Mn deposits
• Least-cost-path analysis?
• Link with Arsenic?
• Oxygen isotopes (Mandernack et al. 1995)?
12
Acknowledgements
This project was supported by a Fondecyt International
Grant (7080013). XRD analyses were performed by Nelson
Guerra at the Universidad Católica del Norte and Peter
Ryan at Middlebury College.
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