PECOS 2016 Geochemical Characterization of a Late PII Kiva Plaster 36 x (original) (raw)
Related papers
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.
Radiocarbon, 2012
The Pre-Pottery Neolithic B (PPNB) site of Yiftahel, Israel, contains abundant plaster floors. We surveyed the states of preservation of the plasters using an infrared spectroscopic assay that characterizes the extent of disorder of the atoms in the calcite crystal lattice. We identified the 3 best-preserved plaster samples that had disorder signatures most similar to modern plaster. We then studied the surface layers, fine-grained matrices, and large aggregates of these samples using micromorphology, Fourier transform infrared (FTIR) microscopy, stable carbon and radiocarbon concentrations. Even though some of the plaster components have a geogenic appearance in micromorphology slides and in FTIR spectra, the 14C analyses show that all components were exposed to high temperatures and as a result were equilibrated with the 14C content of the atmosphere ~10,000 yr ago. This implies that the plasters at Yiftahel were produced entirely from heat-altered calcite. We also show that these...
Plasters : Gypsum or Calcite? A Preliminary Case Study of Syrian Plasters
Une série ďéchantillons d'enduits en provenance de sites des vallées de Balikh et de Khabour ont été soumis à analyse pour étude de leur composition. Les fragments ont été prélevés sur des éléments architecturaux divers (murs, fosses, sols, etc.) représentant des périodes différentes. L'analyse par diffractométrie montre que les échantillons en provenance de contextes néolithiques se composent principalement d'enduits, tandis que les échantillons datant de périodes ultérieures contiennent de la chaux, des enduits, ou un mélange des deux. Il est suggéré que cette differentiation peut s'expliquer par la proximité relative des matières premières aussi bien que par des considérations fonctionnelles.
Radiocarbon 54 (3-4) : 887-896
The Pre-Pottery Neolithic B (PPNB) site of Yiftahel, Israel, contains abundant plaster floors. We surveyed the states of reservation of the plasters using an infrared spectroscopic assay that characterizes the extent of disorder of the atoms in the calcite crystal lattice. We identified the 3 best-preserved plaster samples that had disorder signatures most similar to modern plaster. We then studied the surface layers, fine-grained matrices, and large aggregates of these samples using micromorphology, Fourier transform infrared (FTIR) microscopy, stable carbon and radiocarbon concentrations. Even though some of the plaster components have a geogenic appearance in micromorphology slides and in FTIR spectra, the 14C analyses show that all components were exposed to high temperatures and as a result were equilibrated with the 14C content of the atmosphere ~10,000 yr ago. This implies that the plasters at Yiftahel were produced entirely from heat-altered calcite. We also show that these plasters have undergone significant diagenesis. The plaster component with the most disordered atomic signature, and hence the most similar in this respect to modern plaster, did indeed produce a 14C date close to the expected age.
2007
Most prehistoric plasters and mortars consist of very small amounts of burnt lime mixed with anthropogenic debris, soil, and sediment. To solve the problem of identification of such small amounts of lime in impure lime plasters, a series of experimental plasters were prepared and studied with petrographic methods. Samples of living floors from five prehistoric sites in Greece were also reanalyzed under the light of the experimental findings and compared with natural calcareous sediment. The most promising features for identifying lime are transitional textures of partially carbonized slaked lime that can be observed in the lime lumps and the binding matrix. They are usually in the form of ill-crystallized portlandite and calcite mixtures or cryptocrystalline calcite. Well-reacted calcitic groundmass, shrinkage fractures, and occasionally colloidal forms are also additional indications. The present experimental study shows that lime could be easily produced by heating porous, soft calcareous materials. This would probably account for the very frequent use (in small quantities) of lime in Greek prehistory. Plaster and mortars were made by mixing damp anthopogenic dirt as aggregate and fragments of quicklime, a technique known as “hot mixing.”
Compositional Characterization of Prehistoric Ceramics: A New Approach
Journal of Archaeological Science, 2002
In this paper we present a promising new geochemical provenance technique that couples chemistry-based microwave digestion of archaeological ceramics with Inductively Coupled Plasma-Mass Spectrometry (MD-ICP-MS). MD-ICP-MS data for a standard reference material (SRM-679, brick clay) compare favourably with certified values, and data for prehistoric ceramics from the Virgin Branch Anasazi region of southern Nevada reproduce groups identified in an INAA study. We argue that MD-ICP-MS provides a cost-effective and readily available approach for determining the provenance of archaeological ceramics. As the use of nuclear reactors for archaeological research purposes becomes more tenuous, MD-ICP-MS may also provide a viable alternative for bulk analysis of prehistoric ceramics in the long-term.
Journal of Archaeological Science: Reports, 2016
Infrared (IR) Spectroscopy and microspectroscopy (μ-IR) supported by Environmental Scanning Electron Microscope-Energy Dispersive X-Ray analysis (ESEM-EDX) has been utilised to investigate the technology and use of multicoloured architectural plasters and pigments by Neolithic communities at the archaeological site of Bestansur, Iraq, c. 7,600 BC. Sub-samples of architectural materials and pigments were analysed using IR spectroscopy and fragile samples and thin sections were analysed using μ-IR and ESEM-EDX to determine the mineralogical and elemental composition of individual components and layers and the history of construction and use of three large rectilinear buildings. In addition, experimental investigations were undertaken into the application of IR to study of the firing of calcium carbonate and of clays to investigate if this technique was able to detect evidence of fired-lime materials and of reddening of building materials by fire. Whilst the IR analysis alone was not able to characterise the plasters and pigments, when combined with ESEM-EDX the minerals responsible for pigmentation in the samples were clearly identified. The green clay was determined to be local celadonite-bearing marine clays. The red pigment was found to contain iron, most likely in the form of hematite. The black pigment contained manganese and iron, likely to be present as manganese dioxide and magnetite. The investigations of firing indicate that a hard white exterior may come from fired-lime while a reddish silty clay wall surface had probably not been subject to high-temperature burning. Analysis of a series of wall plasters and pigments from Building 8 (pre-7,600 BC) revealed experiment and development in technologies and materials throughout the occupation of the building, which in the final sequence resemble those from significantly later level at the site of Çatalhöyük, Turkey (c. 7,000 BC).
Dolomite in archaeological plaster: An FTIR study of the plaster floors at Neolithic Motza, Israel
Journal of Archaeological Science: Reports, 2023
Material studies of ancient plaster can provide invaluable information on pyro-technological advancements, living practices, stylistic preferences and possibly the cultural organization needed to produce the plaster. Past studies have established methods of analysis for calcite and gypsum-based plaster, but studies of dolomiterich plaster can be more complicated. In particular, the useful FTIR-based method for determining the structural organization of calcite, which differentiates pyrogenic and geological calcite, is hindered by the overlapping calcite and dolomite peaks. Therefore, a new FTIR-based calibration is presented for quantifying the dolomite percent of the carbonates. This was tested both on known mixtures and in comparison to XRD analyses of ancient plaster. Weighted mixtures of calcite and dolomite were used to demonstrate the problem that dolomite causes when using FTIR to study calcite’s structural order. Limits were established for when dolomite can be considered a small error versus when additional steps must be taken, such as a density separation step to separate disordered calcite from dolomite-rich samples. These methods were applied to a case study of red-painted plaster floors from PPNB Motza. Two types of plaster were found: the plaster preparation layers which contained large aggregates and, based on the new calibration, a high percent of dolomite and some sediment, while the finishing topcoat was almost pure calcite with finer aggregates. The same technology persisted across the examined PPNB building phases. Additional examination by light microscopy was able to clarify the outlier results and provide possible insight on the use of a sunken floor or basin. These methods can now be applied for comparison studies of plaster across sites and time periods, and could also be useful in geological studies where mixtures of calcite and dolomite are present.
PLASTER CHARACTERIZATION AT THE PPNB SITE OF YIFTAHEL (ISRAEL)
The Pre-Pottery Neolithic B (PPNB) site of Yiftahel, Israel, contains abundant plaster floors. We surveyed the states of preservation of the plasters using an infrared spectroscopic assay that characterizes the extent of disorder of the atoms in the calcite crystal lattice. We identified the 3 best-preserved plaster samples that had disorder signatures most similar to modern plaster. We then studied the surface layers, fine-grained matrices, and large aggregates of these samples using micromorphology, Fourier transform infrared (FTIR) microscopy, stable carbon and radiocarbon concentrations. Even though some of the plaster components have a geogenic appearance in micromorphology slides and in FTIR spectra, the 14 C analyses show that all components were exposed to high temperatures and as a result were equilibrated with the 14 C content of the atmosphere ~10,000 yr ago. This implies that the plasters at Yiftahel were produced entirely from heat-altered calcite. We also show that these plasters have undergone significant diagenesis. The plaster component with the most disordered atomic signature, and hence the most similar in this respect to modern plaster, did indeed produce a 14 C date close to the expected age.