Estudios de variabilidad climática y estacionalidad mediante espectroscopía láser

Résumé

Laser induced breakdown spectroscopy (LIBS) is an analytical technique based on the formation of a plasm by the interaction between a high-energy laser pulse and the surface of the analysed material. The subsequent spectroscopic analysis of the light emitted by the plasma allows the identification of the material. LIBS has become a widely used spectroscopic technique due to its advantages, such as its simplicity, speed of analysis and high versatility in size and sample handling. Thus, it has been demonstrated its applicability to a great variety of samples and fields of study: metal alloys, forensics, food, geochemistry, zooarchaeology, medicine, among many others. The main objective of this thesis is the development of an analytical methodology based on LIBS for the study of geological, biological and zooarchaeological samples. The development of this thesis is motivated to elucidate climatic variability, closely related to seasonality and archaeological processes. For this reason, several studies based on laser induced breakdown spectroscopy have been carried out during the development of this thesis to optimize the analysis of tissue samples from zooarchaeological origin, both soft and bone tissue. In this way, this general objective contains other specific objectives, such as obtaining elemental relationships (Mg/Ca, Sr/Ca) using the LIBS technique for the search of paleoclimatic variability patterns in speleothems, according to inter-annual stratigraphy. In addition, the formation of multi-element images of megapixels by LIBS for the analysis of speleothems has been achieved. It has also been studied the dynamics of the plasma by LIBS for the optimization of measurements and greater understanding of the samples. For this reason, other analysis techniques, such as EDX-SEM, have also been used for the study of the surface morphology of the sample. In the field of archaeology, studies have been carried out on collections of present deer bones and fossils, for the study of archaeological sites, using LIBS and chemometric methods (PCA and NN)...