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Physical-archaeological modeling of iron age casemate walls for estimation of their magnetic effect (tel ‘en Gev, Israil)тезисы доклада Тезисы
- Авторы: Коснырева М.В., Itkis S., Соколова Т.Б.
- Сборник: материалы International conference “Archeometrie 2011” Liege, Belgium
- Тезисы
- Год издания: 2011
- Место издания: Universite de Liege, Belgium Liege, Belgium
- Аннотация: Tel ‘En Gev is located at the eastern shore of Lake Galilee, Israel. Many-years excavations show that the site was occupied from the tenth century BCE to the Hellenistic Period. Excavations carried out by a consortium of Japanese universities (1994-2000) revealed straight casemate walls from the Iron Age at the northeastern part of the site. After a break of five years renewed excavations were undertaken on behalf of Archaeological Expedition to Israel, Keio University, Tokyo. The entire southern part of the mound is occupied by the houses and gardens of the Kibbutz ‘En Gev, therefore the area of excavations was limited to the northern part of the mound. For tracing unearthed casemate walls geophysical methods should be applied. Performed excavations provided extensive information on geometrical parameters of casemate walls; which were built of undressed, large-medium sized, basalt boulders. Data available facilitate the development of physical-archaeological models (PAMs) and enable the use of forward modeling as a principal tool for interpretation. To evaluate the pattern of anticipated magnetic anomalies and the attenuation of their amplitudes with the increase of the source's depth, we performed 3D forward modeling of casemate walls using DIPOLI-3 software . We measured magnetic-field profiles across buried continuation of casemate wall and magnetic susceptibility (κ) of stones making up walls in the excavated parts of the site (Fig. 1). Similarly to other archaeological sites in northern Israel [3], basalt building materials in Tel 'En Gev are characterized by relatively high and heterogeneously distributed κ values of basalts: (average κ value is 1300 units SI x10-5, while maxima may reach 5000 units SI x10-5. Average κ values of blackish soils developed on basalts are 190 units SI x 10 -5 and reach 350-400 units SI x 10 -5. Thus, basalt magnetic susceptibility is considerably greater than that of soil. Therefore massive basalt walls due to strong magnetic contrast with surrounding soil will generate positive magnetic anomalies. The intensity of anomalies depends on the depth of the buried basalt remains and their size. Fig. 1. Magnetic susceptibility along casemate wall (white symbols show points of κ measurements). We calculated PAMs presented casemate walls buried on three different depths: close to the surface (0-10 cm), 50 cm and 1 m in accordance with the thickness of subsoil in Tel 'En .Gev. Walls are composed of basalt stones which have 20-25 to 40-50 cm in cross-section. Unearthed remains have the whole thick of the structure 4.5 m, which includes 1.5 m of outer wall, 1.5 m of inner casemate and 1.5 m inner wall [5]. Casemate walls were approximated by elementary cubes, each with a side of 0.3 m. The walls contain 30 elementary cubes in length, and 5 elementary cubes in width and height. Magnetic susceptibility values of elementary cubes were chosen in accordance with our κ measurement and their statistical distribution. The results of calculations show that for the casemate walls buried close to the surface, these remains can be clearly traced by double chain of positive anomalies. With the increase of the soil thickness up to 1 meter and more, the anticipated casemate wall will produce the single magnetic anomaly of smoothed configuration with amplitude of 150-200 nT which is more than enough to be indicated. Nevertheless, due to high contamination of the site with the iron trash the source of the anomaly cannot be reconstructed completely and the reliable interpretation of magnetic data will be extremely difficult.
- Добавил в систему: Соколова Татьяна Борисовна