Geography of Eastern Anatolian obsidian: sources, characterization and diffusion during prehistoric times. – GeObs

The GeObs project is organized into three scientific tasks:

1. study of the availability of obsidian sources and its evolution during the Upper Pleistocene and Holocene
1.1. location and identification of obsidian outcrops
1.2. Obsidian settings
1.3. Regional morphotectonic and environmental evolution

The methods used for this first task are :
- field investigation for both morphological and geomorphological settings;
- exhaustive sampling of all the outcrops of the 13 regions with obsidian in Eastern Anatolia;
- cartography of obsidian outcrops;
- implementing the database (including description of the sections samples, photography, drawing, etc.)

2. Characterization of obsidian sources
2.1. Determining geochemical fingerprints;
2.2. Other characterisation techniques:
2.3. Statistical analyses

The methods used for this second task are :
- geochemistry : in-situ (p-XRF), and lab. analyses (LA-ICP-MS, XRF)
- magnetic properties, radio-isotopic dating, petrography and mineralogy
- multivariate analyses in order to create homogeneous groups of obsidian (=sources) at different scales.

3. Spatial diffusion of the obsidian: from geological sources to archaeological sites
3.1. Archaeological and geochemical analyses of artefacts within collections
3.2. Mapping and integrating data in the spatial database
3.3. Spatial analyses of diffusion processes

The methods used for this third task are
- lithics analyses (technological and typological);
- portable in-situ analyses of the artefacts;
- implementing the database (description of the artefacts and their archaeological setting)
- spatial analyses in order to precise diffusion processes and diffusion paths.

The main results of GéObs project deal with : 1) acquisition of new data as well as 2) methodological developments.

1. We have acquired new data in each of the scientific task of the project:
1.1. Obsidian availability (task 1): in Eastern Anatolia, obsidian outcrops in 13 regions. A third to an half of these regions have been already investigated.
1.2. Characterization of the geological sources (task 2): 492 samples have been characterized using geochemistry (both LA-ICP-MS and p-XRF) and physical properties (petrography, mineralogy, etc.). We thus have greatly improved our knowledge of the eastern Anatolian obsidian sources.
1.3. Spatial diffusion from the geological sources to the archaeological sites (task 3): in-situ analyses of the artefact collection from Arslantepe excavation and from Erzurum and Kars museum, using p-XRF.

2. Methodological developments:
2.1. GeObs database include the informations concerning: i) the geological sources; ii) the artefacts; iii) the analyses of both sources and artefacts (geochemistry, dating, etc.)
The database has been developed using MySql. It will be available for all the GeObs team at the end of 2015. It will be later available for the scientific community at the end of the GeObs project.
2.2. The in-situ study of the sources and archaeological artefact is based on the use of the p-XRF analyser. We have developed an analytical protocol in order to ensure repeatability and precision of the measurements.
2.3. Part of the GeObs team is working on a statistical approach for attributing the artefact to a geological source. It is based on multi-varied method together with probabilistic approach and expert knowledge.

During the 30 next months of GeObs project, the future prospects are:

We will continue to work in the framework of scientific tasks 1, 2 and 3, in order to get an exhaustive knowledge of the Eastern Anatolian obsidians.
All the results concerning the geological sources, the artefact and all the analyses will be implemented within the database.

Moreover, two complementary outstanding features will be developed:

1) thanks to the recruitment of a post-doc. during 2015-2016, we will be able to increase the number of archaeological collections to be studied. We will thus develop the study of the spatial diffusion of obsidian in the Near-East.

2) Among the methodological features, the 2015-2016 period will focus on the development of the statistical toll allowing an attribution of the archaeological artefact to a precise source.

Since the beginning of the project, the first results have been presented through scientific papers in (inter)national journals, and through oral communication and posters in national and international symposium.

1. Scientific journals:
1.1. in prep. : 1 (Journal of Archaeological Science)
1.2. submitted: 1 (Géomorphologie)

2. International symposiums:
2.1. oral communications: 5
2.2. posters: 3

3. National symposiums:
3.1. oral communications: 7
3.2. posters: 3

GeObs is a basic research program in Human Sciences. We propose a multi-disciplinary approach of one of the most impressive archaeological phenomenon in recent Prehistory: the exploitation of Anatolian obsidian by ancient groups to manufacture tools and prestige objects and its spatial diffusion through exchange networks among communities over the whole Near-East (including Anatolia and Caucasus). We propose to analyse the volcanic context and to characterize in detail the 13 main sources recognized in Eastern Anatolia. Indeed, they are still insufficiently known and characterized in order to allow the analysis of the diffusion from geological sources to archaeological sites.
The aim of the project is to establish a detailed database and geographical information system of the obsidian sources in eastern Anatolia. We thus propose an integrated and pluridisciplinary approach for obsidian sourcing based on:
1. Intensive field research. The aim is to study the volcanological settings of the obsidians that control their fingerprint as well as their morphological settings that constraint their accessibility through time. This study will concern primary geological sources as well as secondary reworked obsidians.
2. Multi-methods characterization of obsidian. We will analyse the geological samples as well as archaeological artefacts in order to characterize their fingerprints, using chemical (LA-ICP-MS, XRF and p-XRF) and physical properties (magnetic properties, petrography, mineralogy). The geological samples will be analysed in High-Tech laboratories, whereas artefacts will be analysed using portables in-situ method (p-XRF). We will thus pay a special attention to inter-method comparison and to the validation of p-XRF method. All the results will be analysed with the help of multivariate analysis. Finally they will be interpreted using the results of field investigation.
3. Spatial analyse and diffusion. We will compare the characterization of geological samples with the analyses of the archaeological data in order to understand the diffusion processes. Concerning the archaeological data, we will use the new p-XRF data obtained in the framework of the GeObs program concerning Anatolian excavations as well as already published data on artefacts made in the whole Near-East. Using the methods of spatial analyse we will try to understand the diffusion of the obsidian during Prehistoric times, from geological sources to archaeological sites.
All the data produced during this 4 years project will be integrated in a database and a G.I.S. They will be diffused to the scientific community through a dedicated website, after the publication of the results in international journals.
In 2012, a first version of the GeObs project has been proposed to ANR JCJC program and positively evaluated since it was included in the “complementary list”. We now propose a renewed version of the project.
Our French and Turkish team is based on already existing collaborations. It is formed to conduct an interdisciplinary research combining geomorphology, geology, archaeology and archaeosciences. Our team is composed of highly experienced scholars who have already published in international papers in the fields interested by this project (e.g.: volcanic geomorphology, obsidian sourcing, obsidian characterization, diffusion processes or Neolithic of Anatolia).