Characterisation of charred organic matter in micromorphological thin sections by means of Raman spectroscopy

Glenn Lambrecht, Caterina Rodríguez de Vera, Margarita Jambrina-Enríquez, Isabelle Crevecoeur, Jesus Gonzalez-Urquijo, Talía Lazuen, Gilliane Monnier, Goran Pajović, Gilbert Tostevin, Carolina Mallol

Research output: Contribution to journalArticlepeer-review

Abstract

Burned or charred organic matter in anthropogenic combustion features may provide important clues about past human activities related to fire. To interpret archaeological hearths, a correct identification of the organic source material is key. In the present work, Raman spectroscopy is applied to characterise the structural properties of char produced in laboratory heating- and open-fire experiments. This reference data set is compared to analyses of three different archaeological sites with Middle Palaeolithic combustion contexts. The results show that it is possible to determine whether a charred fragment is the product of burning animal-derived matter (e.g. meat) or plant-derived matter (e.g. wood) by plotting a few Raman spectral parameters (i.e. position of G and D bands, and intensity ratios HD/HG and HV/HG) against one another. The most effective parameters for discriminating animal- from plant-derived matter are the position of the G band and the HV/HG intensity ratio. This method can be applied on raw sample material and on uncovered micromorphological thin sections. The latter greatly compliments micromorphology by providing information about char fragments without any clear morphological characteristics. This study is the first of its kind and may provide archaeologists with a robust new method to distinguish animal- from plant-derived char in thin sections.

Original languageEnglish (US)
Article number13
JournalArchaeological and Anthropological Sciences
Volume13
Issue number1
DOIs
StatePublished - Jan 2021

Bibliographical note

Funding Information:
The authors thank Inocencio Rafael Mart?n Benenzuela for providing access to the Raman instrument at the department of physics and IMN of the University of La Laguna (ULL) in Tenerife, Spain. Tammy Buonasera is thanked for providing a reference sample and proofreading the manuscript. Pedro Garc?a Villa is acknowledged for performing an initial microscopic screening of different types of char particles. Comments by two anonymous reviewers improved this manuscript and are greatly appreciated.

Funding Information:
This research was supported by the ERC Consolidator Grant project PALEOCHAR—648871. Research at the Axlor site is funded by the Spanish Ministry of Science and Innovation (Project PID2019-107260GB-I00). Research at Crvena Stijena is funded by the Montenegrin Ministry of Culture, the United States National Science Foundation (NSF-BCS 1758285) and the University of Minnesota Grant-in-Aid of Research. The Collaborative Research Project ‘PCR La Roche-à-Pierrot’ is funded by the Regional Service of Archaeology from Nouvelle-Aquitaine region and the Charente-Maritime Department, France.

Publisher Copyright:
© 2021, The Author(s).

Keywords

  • (micro-)Raman spectroscopy
  • Archaeology
  • Char
  • Charcoal
  • Fire
  • Micromorphology
  • Pyrotechnology
  • Tar

PubMed: MeSH publication types

  • Journal Article

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