Consideration on the construction process and the sandstone quarries during the Angkor period based on the magnetic susceptibility

Detailed magnetic susceptibility measurement was conducted on the sandstones used for the Angkor monuments constructed in the period spanning the Preah Ko and Angkor Wat styles, and the construction process of the buildings and quarries of the sandstones was considered. Combined with the previous study on the sandstones of the Bayon style [Uchida, E., Cunin, O., Shimoda, I., Suda, C., Nakagawa, T., 2003. The construction process of the Angkor monuments elucidated by the magnetic susceptibility of sandstone, Archaeometry 45, 221–232], the magnetic susceptibility measurement revealed that there were 7 sandstone quarries corresponding to Stages I, II, III, IVa, V, VII and VIIIb during the Angkor period. The sandstones used for the monuments belonging to Stage I show average magnetic susceptibility values ranging from 1.1 to 2.3 × 10⁻³ SI units. In the Bakheng style period (Stage II), the average magnetic susceptibility of the supplied sandstones decreased gradually from around 10 to 1 × 10⁻³ SI units over time. The magnetic susceptibility range of the sandstones used for the monuments of Stage III was from 2.3 to 3.0 × 10⁻³ SI units. In the early Angkor Wat style period (IVb), the average magnetic susceptibility of the supplied sandstones increased over time, reflecting the supply of the sandstones from two different quarries, that is, the quarry corresponding to the Khleang and Baphuon style monuments (Stage IVa), with low average magnetic susceptibilities of 1.1 to 2.4 × 10⁻³ SI units, and the quarry corresponding to the main Angkor Wat style monuments (Stage V), with high average magnetic susceptibilities ranging from 2.8 to more than 4.3 × 10⁻³ SI units. The sandstones of Stage VII show low average magnetic susceptibility around 1 × 10⁻³ SI unit. The sandstones of Stage VId is a mixture of sandstones of Stages V and those of Stage VII. The sandstones with high magnetic susceptibilities are found in the monuments belonging to Stage VIIIb, reflecting the supply from the new sandstone quarry.