Anàlisi química de sediments arqueològics de fogars de jaciments de terra del foc (Argentina)

Abstract

The main hipótesis raised in this doctoral thesis is whether the organic chemistry análisis can provide new data, expand and verify the information that we usually obtain during the excavation of an archaeological site with the application of traditional study techniques, like, the análisis of the lithic industry, archaeofauna, the paleovegetation, and the study of sediments with soil micromorphology, etc. These analices has been carried out in Tierra del Fuego sites within different research projects carried out by the University Autónoma of Barcelona and IMF-CSIC of Barcelona together with other Institutes an Research Centers. These yamana settlements are contemporary with the arrival of the first European settlers in the area and have been described by ethnographic reports by different authors. We can therefore contrast the data obtained from the excavation with the written data of the same age. Samples have been collected on three archaeological sites were huts of these hunter-gatherer society have been identified: Túnel VII, Lanashuaia and Ajej. From the Túnel VII site, a superposition of ten fireplaces have been analyzed. These have been used at different times and seasons of occupation. From Lanashuaia site three fireplaces have been analyzed: one from the main center of the hut, one at the entrance of the hut, and another one from the outside. A sample of sediment adhered at a concentration of pebbles used to heat fats has been also analyzed. In addition, a sample of non burnt sediment of the Túnel VII has been also analyzed to get the information as blank of the archaeological sediment matrix. The chemical análisis used is the one normally used by the Department of Environmental Chemistry of the CSIC of Barcelona in their analyses of paleo-sediments. The organic matter of the sediment sample is extracted by solvents (with soxhlet or by ultrasound) and then sponified to separate the neutral fractions from the acid fraction. The neutral fraction is separated again by column chormatography adsorption. According to the polarity of the solvent used three different fractions are obtained: aliphatic hidrocarbons, aromatic hidrocarbons, and alcohols and sterols. These fractions are analyzed by gas chormatography and mass spectometry and the resulting compounds are identified and quantified. The results are compared with references already analyzed or directly identified through the presence of known biomarkers (from literature) to know materials have been used during the ignition of the fireplace, the function, posible duration of the ignition and to know the taphonomic proceses that affect the chemical compounds as web as to know what has to be taken into account when trying to identify the posible origins of the chemical organic composition of sediments. We have compared the results with the data obtained with the studies of traditional archaeological materials ant this has confirmed some of the existing data and, what is more important, the presence of biomarkers such as isoprene-acids (from marine mammals) and some hydroxyacids (α-hydroxyacids derived from bivalves) which confirms these data and will help to identify the functionality of fireplaces.

Date of Award	30 Oct 2018
Original language	English
Supervisor	Jordi Estevez Escalera (Director) & Joan Grimalt Obrador (Director)