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PhD Abstract

The research undertaken in this thesis, aims to identify the formation processes of the pre-Columbian archaeological anthropogenic soils in the French Guiana territory as well as to contribute to revisiting ancient human activities. It is based on the study and analysis of the intrinsic properties of archaeological sediments, such as, on the one hand, their nature and their pedo-sedimentary composition, and on the other hand, their physicochemical properties. The availability of a corpus of open air archaeological sites in different geomorphological settings (e.g., floodplain; lateritic hill with circular ditch glossed in French montagne couronnée), and the implementation of a geoarchaeological approach combining micromorphological observations and physicochemical analyses, enabled to investigate different kinds of pre-Columbian anthropogenic soils in French Guiana, and to characterize them according to several anthropogenic markers, both direct and indirect. Geoarchaeological analysis revealed that the natural pedogenesis has been impacted by the ancient anthropization and indicates a certain resilience of soils. The soil micromorphology demonstrated anthropogenic microtraces such as charcoal (micro and macro) and fragments of pottery, common to both contexts, as well as different kinds of heated aggregates originating from the surface of the soils having been burned, only for the montagnes couronnées sites. Anthropogenic activity probably also contributed to the process of leaching of clay via the formed ashes. The pedofaune has been transformed as one may assume, in thin sections, the presence of pedofeatures related to Pontoscolex corethrurus. Additional archaeo-environmental analyses implemented in this study (anthracology, phytoliths, magnetic susceptibility) allowed completing the data acquired on the implementation of the studied anthropogenic soils. These studies, pioneering for French Guiana, though inspired by studies in the near Brazilian Amazon on terra preta/mulata or Amazonian Dark Earth, complement the repository of archaeological anthropogenic soils developed in the Amazon. Furthermore, they allowed several hypotheses about the origins of the activity markers, either direct or indirect, observed in the archaeological anthropogenic soils, and evidenced ancient human events that could have taken place on the sites studied. Fundamental activities such as house fires or the cultivation of the land appear to have taken place on the latter. Assumptions about the models of occupation of space have been proposed mainly by refuse areas behind the supposed houses and near the ditch in the case of the montagnes couronnées. This study is situated in an archaeo-environmental approach demonstrating the close relations between pre-Columbian populations with their environment.

Résumé Les recherches entreprises dans cette thèse visent à définir les processus de formation des anthroposols archéologiques précolombiens sur le territoire guyanais ainsi qu’à participer à la restitution des activités humaines passées. Elles sont fondées sur l’étude et l’analyse des propriétés intrinsèques des sédiments archéologiques, telles que, d’une part, leur nature et leur organisation pédo-sédimentaires, et d’autre part, leurs propriétés physico-chimiques. La possibilité de disposer d’un corpus de sites archéologiques de plein air dans différents contextes géomorphologiques (plaine alluviale, colline latéritique pour les montagnes couronnées), et la mise en place d’une approche géoarchéologique combinant observations micromorphologiques et analyses physico-chimiques, a permis d’investiguer différents types d’anthroposols précolombiens guyanais, et de les caractériser suivant plusieurs marqueurs anthropiques, directs et indirects. L’analyse géoarchéologique révèle que la pédogénèse naturelle a été impactée par l’anthropisation ancienne et indique une certaine résilience des sols. La micromorphologie des sols a permis de mettre en évidence des microtraces anthropiques telles que des charbons (micro et macro) et des céramiques, communs aux deux contextes, ainsi que différents types d’agrégats brûlés provenant de la surface des sols ayant subi la chauffe pour les montagnes couronnées. L’activité anthropique a aussi probablement favorisé les processus de lessivage des argiles par des apports anciens de cendres. La pédofaune a été transformée comme le laisse supposer, en lames minces, la présence de traits rapportés à Pontoscolex corethrurus. Les analyses archéo-environnementales complémentaires mises en place dans ce travail (anthracologie, phytolithes, susceptibilité magnétique) ont permis de compléter les données acquises sur la mise en place des anthroposols étudiés. Ces travaux, précurseurs pour le territoire guyanais, et en s’inspirant des études menées non loin, en Amazonie brésilienne sur les terra preta/mulata ou Amazonian Dark Earth, viennent compléter le référentiel des anthroposols archéologiques développés en Amazonie. Ils ont, en outre, permis d’émettre plusieurs hypothèses quant à l’origine des marqueurs d’activités, directs ou indirects, observés dans les anthroposols archéologiques, et de mettre ainsi en évidence les manifestations humaines anciennes qui auraient pu avoir lieu sur les sites étudiés. Des activités fondamentales telles que les foyers domestiques ou la mise en culture des sols semblent avoir pris place sur ces derniers. Des hypothèses sur les modèles d’occupation de l’espace ont été proposées en s’intéressant aux zones de rejet principalement, situées en retrait des maisons supposées et à proximité du fossé dans le cas des montagnes couronnées. Cette étude s’inscrit typiquement dans une approche archéo-environnementale qui vient préciser les liens étroits qu’entretenaient les populations précolombiennes avec leur environnement. Mots clés : Géoarchéologie amazonienne, anthroposols archéologiques, micromorphologie, géochimie, terra preta/mulata, peuplements précolombiens, Guyane française. Abstract The research undertaken in this thesis, aims to identify the formation processes of the pre-Columbian archaeological anthropogenic soils in the French Guiana territory as well as to contribute to revisiting ancient human activities. It is based on the study and analysis of the intrinsic properties of archaeological sediments, such as, on the one hand, their nature and their pedo-sedimentary composition, and on the other hand, their physicochemical properties. The availability of a corpus of open air archaeological sites in different geomorphological settings (e.g., floodplain; lateritic hill with circular ditch glossed in French montagne couronnée), and the implementation of a geoarchaeological approach combining micromorphological observations and physicochemical analyses, enabled to investigate different kinds of pre-Columbian anthropogenic soils in French Guiana, and to characterize them according to several anthropogenic markers, both direct and indirect. Geoarchaeological analysis revealed that the natural pedogenesis has been impacted by the ancient anthropization and indicates a certain resilience of soils. The soil micromorphology demonstrated anthropogenic microtraces such as charcoal (micro and macro) and fragments of pottery, common to both contexts, as well as different kinds of heated aggregates originating from the surface of the soils having been burned, only for the montagnes couronnées sites. Anthropogenic activity probably also contributed to the process of leaching of clay via the formed ashes. The pedofaune has been transformed as one may assume, in thin sections, the presence of pedofeatures related to Pontoscolex corethrurus. Additional archaeo-environmental analyses implemented in this study (anthracology, phytoliths, magnetic susceptibility) allowed completing the data acquired on the implementation of the studied anthropogenic soils. These studies, pioneering for French Guiana, though inspired by studies in the near Brazilian Amazon on terra preta/mulata or Amazonian Dark Earth, complement the repository of archaeological anthropogenic soils developed in the Amazon. Furthermore, they allowed several hypotheses about the origins of the activity markers, either direct or indirect, observed in the archaeological anthropogenic soils, and evidenced ancient human events that could have taken place on the sites studied. Fundamental activities such as house fires or the cultivation of the land appear to have taken place on the latter. Assumptions about the models of occupation of space have been proposed mainly by refuse areas behind the supposed houses and near the ditch in the case of the montagnes couronnées. This study is situated in an archaeo-environmental approach demonstrating the close relations between pre-Columbian populations with their environment. Key words: Amazonian geoarchaeology, archaeological anthrosols, micromorphology, soil geochemistry, terra preta/mulata, Pre-Columbian peoples, French Guiana. Résumé / Abstract / Resumo / Resumen