Technology and decay of magnesian lime plasters: the sculptures of the funerary crypt of Palenque, Mexico (original) (raw)
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Characterization and Provenance of Lime Plasters From the Templo Mayor of Tenochtitlan (Mexico City)
Archaeometry, 2011
In this work, we present the results of the analyses of 20 lime plaster samples taken from the Templo Mayor (Great Temple), the main pyramid of Tenochtitlan (Mexico), the ancient capital of the Mexicas. The samples were analysed to recover information on the mixtures used in the fabrication of the plasters and for the provenance of the raw materials (in particular, limestone) used to make the plasters. The characterization of the samples was done by OM, SEM/EDS, XRF and LA-ICP-MS analyses, while the identification of the provenance of raw materials was done by studying the lumps present in the samples with LA-ICP-MS. The objective of the study was to establish if there was a relationship between changes in the construction techniques employed in the pyramid over time and if there were changes in the provenance of the raw materials. Six different construction phases of this pyramid are analysed, showing the similarities and differences among them, mainly based on differences in the sieving of the aggregates and in the raw materials employed. The provenance studies of the limestone used to make the plasters demonstrated that all the limestone comes from the Tula region.
Archaeometry, 2013
In this work, we present the results of the characterization of 20 lime plaster samples taken from the Sacred Precinct of Tenochtitlan (Mexico City), the ancient capital of the Aztec empire. The samples come from different buildings of this precinct (A, B and D) and from the west façade of phase VI of the Templo Mayor pyramid. The objective of the work is to characterize the plaster samples, to understand the raw materials used, and to evaluate the presence of similarities and differences among the samples in the building techniques and raw materials employed. All the samples were studied with OM, SEM-EDS and LA-ICP-MS. The study provided evidence of the plastering and replastering practice in the same constructive phases. The results of the analyses showed the existence of important similarities and differences among buildings and constructive phases in the Sacred Precinct. In order to understand the provenance of the limestone used in the plasters, the lumps and the binder of the samples were analysed. The results were compared with those of the limestone outcrops located in central Mexico. The provenance study showed that all the limestone used in the construction of the analysed buildings of Tenochtitlan's Sacred Precinct comes from the Tula region.
Archaeomagnetic investigation of oriented pre-Columbian lime-plasters from Teotihuacan, Mesoamerica
Earth, Planets and Space, 2006
Results of an archaeomagnetic study of two excavation field seasons at the Xalla and Teopancazco residential areas of the ancient Prehispanic city of Teotihuacan, Central Mexico are reported. One-hundred and fifty three oriented samples of lime-plasters from the two archaeological sites were collected for the study. NRM directions are reasonably well grouped. Alternating field demagnetization shows single or two-component magnetizations. Rock magnetic measurements point to fine-grained titanomagnetites with pseudo-single domain behaviour. Characteristic site mean directions from both sites are correlated to the available palaeosecular variation curve for Mesoamerica. The mean directions obtained from Xalla site point to average dates of 550 AD±25 years that matches with the documented ‘Big Fire’ of Teotihuacan (AD 575). Two consecutive construction levels at Teopancazco were estimated as AD 250–350 and AD 350–425 respectively.
Characterization of lime plaster of a Portuguese medieval monument in the Indian Ocean coast
The present study aimed to unravel important features regarding the ancient lime plaster of a Portu-guese monument in the Indian Ocean coast for the formulation of compatible repairing materials and to determine its condition to plan conservation works. The study illustrates the hydraulic properties of lime used for the construction, the extent of salt intrusion into the plasters, area of intrusion and its source. Wet chemistry results reveal that the dampness and capillary actions led to salt diffusion into the walls and its percolation to different heights of the monument. Due to the intrusion of water into the matrix of the plaster, its inner core becomes less cohesive, resulting in brit-tleness of lime combination and peeling-off of the upper fabric. Thermal techniques, X-ray diffraction and X-ray fluorescence results identified the mineralogical composition of the construction materials, viz. lime plaster and mortar. Further, they confirmed the uniqueness of lime combination used to build the monument with lime-silica ratio in the range 1 : 1 to 4 : 1 and its transformations over a period of time in saline atmosphere. This study provides an overview regarding the ancient lime plaster used in the monument and may help to devise new compatible materials for subsequent conservation works.
Archaeomagnetic studies in central Mexico—dating of Mesoamerican lime-plasters
Physics of the Earth and Planetary Interiors, 2004
For the first time results of an archaeomagnetic study of unburned lime-plasters from Teotihuacan and Tenochtitlan in central Mesoamerica are presented. Plasters made of lime, lithic clasts and water, appear during the Formative Period and were used for a variety of purposes in ...
Results of an archaeomagnetic study of two excavation field seasons at the Xalla and Teopancazco residential areas of the ancient Prehispanic city of Teotihuacan, Central Mexico are reported. One-hundred and fifty three oriented samples of lime-plasters from the two archaeological sites were collected for the study. NRM directions are reasonably well grouped. Alternating field demagnetization shows single or two-component magnetizations. Rock magnetic measurements point to fine-grained titanomagnetites with pseudo-single domain behaviour. Characteristic site mean directions from both sites are correlated to the available palaeosecular variation curve for Mesoamerica. The mean directions obtained from Xalla site point to average dates of 550 AD±25 years that matches with the documented 'Big Fire' of Teotihuacan (AD 575). Two consecutive construction levels at Teopancazco were estimated as AD 250-350 and AD 350-425 respectively.
Journal of Archaeological Science, 2012
This paper introduces for the first time the study and description of fossil remains preserved in lime plaster from a Maya site, the Temple of the Inscriptions in Palenque, one of the most outstanding Classic Period cities of the Maya culture in Mesoamerica. Plaster was removed with EDTA carbonate-digestive technique and results based on ultrastructural microanalysis reveals marine fossil remains of shells and calcareous debris correlated with organisms of several taxa including Foraminifera, Gastropod, Bivalvia, and Cnidarian. This fossil material is associated with several Tertiary fossil-bearing strata in the surroundings of Palenque. Additionally, results of WDX testing on white lumps of plaster show a characteristic MgO/CaO ratio consistent with a dolomitic limestone source linked to the Tenejapa geological unit (Paleocene). Plaster of The Temple of the Inscriptions is best described as a dolomitic lime plaster. Calcareous fossil material in plaster mixtures is present mainly as micro-aggregates and lime dust, such material may come from a fossil-bearing rock intentionally selected that was burned and crushed. This also suggests that low-temperatures can cause burns to incomplete calcination of rocks and, consequently, that fossils can preserve their recognizable, morphological features.
Identifying a technological style in the making of lime plasters at Teopancazco (Teotihuacan, México
The aim of this article is to focus on the technology of archeological plasters at Teotihuacan (Central Mexico), from the Classic Period (200–650 A.D.), focusing in the study of Teopancazco, a neighborhood center in the city. Petrographic and chemical analyses by OM, SEM-EDS, and LA-ICP-MS were conducted to characterize samples from different constructive phases and sectors of the neighborhood center, to determine the provenance of the raw materials employed in the manufacturing (e.g., volcanic glass shards) and to assess whether a shift occurred in the manufacturing of plasters and in the procurement strategies of raw materials during the different phases. The results of the analyses show that almost no changes occurred in the making of the plaster during more than four centuries and allow us to consider the presence of a technological style in their manufacture, which is characterized by the making of plaster by mixing lime with volcanic glass shards, which in the case of Teopancazco were derived from the Altotonga (Veracruz) magmatic system. The data at our disposal suggest that this style was developed in Teopancazco and later introduced throughout the city of Teotihuacan in the Early Xolalpan phase (A.D. 350), although we still do not know whether the provenance of the raw materials is the same. The wide distribution of this technological tradition could be due to the technological properties of the materials and/or the influence of the intermediate elite who ruled over Teopancazco. The paper confirms that the study of material culture and technology sheds light on broader cultural aspects of ancient societies.
Characterization and Comparative Analysis of Ancient Earthen Plasters from the American Southwest
MRS Advances, 2017
We have studied earthen plasters and wall materials from three ancestral Native American sites in the American Southwest that include a twelfth-century, subterranean kiva used for textile production in Natural Bridges National Monument (Utah), a thirteenth-century, defensive, cliff dwelling at Montezuma Castle (Arizona), and a mid-fourteenth-century, puddled earth Great House at Casa Grande National Monument (Arizona). In each case, the data collected has been used to develop long-term preservation strategies and monitoring plans for each site. To understand the conservation issues, earthen materials were analyzed. Characterization included examination of BSE-SEM micrographs of polished thin sections prepared from a total of 36 samples from the three sites, and XRD of twelve samples. Research goals included: 1) determining the microstructure, micro-composition, porosity, mineralogy of aggregates and phases in the binding matrix for each sample; 2) reconstructing plaster technologies and their variation within and between sites, including material selection, preparation and application sequences, and; 3) identifying principal deterioration conditions and processes. Our findings support the idea that plaster materials were collected locally and manipulated to optimize their performance to suit the unique site conditions and needs of the ancient people using the structures.