Full-scale modelling of GPR sounding of Kolyma River bottom in searching for bone remains of mammoth fauna animals

The fossil mammoth tusk is a unique biogenic material, which is widely used for the production of souvenirs and luxury goods. The burial of mammoth fauna animal’s remains in permafrost ensured high preservation. Due to the complete ban on hunting African and Asian elephants introduced in 1990 by UNESCO, the demand for fossil ivory has increased. Today, up to 80 % of mammoth bone deposits is harvested in the Republic of Sakha (Yakutia), Russia. The paper describes some traditional techniques of mammoth tusk mining and proves the efficiency of the GPR (ground penetrating radar) for prospecting underwater accumulations of fossil mammoth bone. The aim of the survey was increasing the efficiency of the GPR sounding technique for the detection of mammoth bone under water. The comprehensive GPR area survey was used to identify areas promising to contain underwater accumulations of fossil mammoth bone. Because the release of bone material from productive layers is caused by river erosion and thermal erosion processes a meandering section of the Kolyma River was selected for the research. Thermal erosion plays a more prominent role in the release of bone material in the headwaters of small watercourses, in deltas, and in the bottoms of incipient gullies. Fossil mammoth bones are usually found on riverbanks (low floodplain, channel spits) — in areas where the river erodes the slopes of remnants composed of edomorphic complex formations or in close proximity to them. The GPR application makes it possible to study the bottom relief in detail and thus can identify areas promising in terms of the formation of secondary accumulations of mammoth bones. The key features of bone remain accumulations have been identified: natural depressions or obstacles that mammoth bone can get caught on when sinking to the bottom of the water body; accumulation of the heaviest fragments in the deepest depressions at the bottom of the water body; accumulation of smaller fragments on sedimentary shoals. An algorithm for the GPR surveying of water bodies promising in terms of mammoth bone detection has been developed.