Geophysical investigation of kurgans in Uzun Rama steppe, Goranboy region, Azerbaijan

Kurgans are funeral chambers, evidence of burial tradition dating back to the first thousand years BCE, of nomadic populations that covered a vast area in-between Europe and Asia. In Azerbaijan, past archaeological explorations revealed numerous large kurgans from the Early Bronze, which correspond to Kura-Arexed period (ca. 3500-3000 BCE), and relatively smaller burials of Late Bronze/Early Iron Ages. To improve the efficiency of the excavation process, geophysical methods have been widely and effectively applied for many years to provide clear and useful images of archeological targets hidden underground such as kurgans.

In this work, we introduce a multi-method archaeo-geophysical survey done in May 2022 to investigate Early Bronze Age kurgans located in Uzun Rama Steppe of Goranboy region in Azerbaijan. Applied method cover different depth of investigation and resolution to provide a wealth of information on the structure of three kurgans aligned in a North-South direction. It comprises coincidental DC-resistivity and seismic refraction tomographies of 70.5 m with a 1.5 m spacing going over all kurgans, a Ground Penetrating Radar (GPR) 40 m long profile using a 500 MHz antenna on the northern kurgans going from East to West and a magnetic map 24 x 25 m on the southern one.

The DC-resistivity profile shows two layers, a medium resistivity layer (500 to 600 W.m) from the surface to 6 m depth and a very conductive layer (> 10 W.m) under it. The first layer contains three areas of lower resistivity (~ 60 W.m) that are limited in thickness and length. As these three spots are marked by higher height on-site, we interpret them as the three kurgans. The coincidental seismic profile is a lot less detailed (due to physical properties and higher spacing between receiver) and define only three homogeneous layers, a first layer from the surface to 1 m depth with a P-wave velocity of 300 m/s, a second layer of higher velocity (1000 m/s) from 1 m depth to approximately 6 m depth and a final third layer of 2000 m/s velocity. Even though, the resolution is lower, we interpret the first layer as an attempt of the model to represent the kurgans. The GPR profile give a high attenuate image due to low resistive layer. However multiple diffractions can be seen in the first meter of the subsurface that can indicate the presence of ancient artefact related to the kurgans. Finally, the magnetic map defines the limit of the kurgan as a positive-negative anomaly probably due to the burning ritual that ended the implementation of a kurgan.

This geophysical campaign allowed us to accurately locate the kurgans as well as provide information on the environment. DC-resistivity and magnetic mapping seem to get the best results in our case. A future archaeological investigation will be put in place based on these results.