Construction sequence of the Koh Ker monuments in Cambodia deduced from the chemical composition and magnetic susceptibility of its laterites

Abstract

Introduction: Koh Ker, one of the provincial cities of the Khmer Empire, was located approximately 85 km northeast of the Angkor monuments. The temples in the Koh Ker monuments were mainly constructed from laterite, sandstone and brick between 921 and 944 AD. The laterites used in the Koh Ker monuments are difficult to classify based on their appearance. However, using a portable X-ray fluorescence analyzer it was possible to distinguish two distinct types of laterite based on Sr content. Results: Laterite blocks used in construction of the Koh Ker monuments either had a low Sr content of less than 300 ppm or a high Sr content of greater than 400 ppm. Significant quantities of quartz were observed in the low Sr content laterites, whereas the high Sr content laterites had relatively low quartz content. Differences in the magnetic susceptibility also were observed for these laterites. Using both Sr contents and magnetic susceptibilities of the laterite blocks, in combination with the assumption that the construction site proceeded in an outward manner, we identified five distinct laterite types associated with different stages of construction.

Precipitation of manganese oxides on the surface of construction materials in the Khmer temples, Cambodia

“…The Mn content is generally less than 0.3 % in sandstone, laterite, and bricks [1,2]. However, laterite at the Koh Ker monuments contains more Mn (0.3-2.4 %) [9]. This may be one of the reasons why precipitation of manganese oxides is remarkable on the surface of laterite at the Koh Ker monuments.…”

Construction Sequence of the Koh Ker Monuments Constrained by the Chemical Composition and Magnetic Susceptibility of Its Bricks

“…Based on the chemical composition and magnetic susceptibility of laterite, Uchida et al (2014) assigned the laterite buildings in the Koh Ker monuments to five construction stages. In particular, Uchida et al (2014) used Sr content of the laterite to divide the laterite buildings into two groups, using a value between 300 to 400 ppm.…”

“…Because little difference in the chemical composition or magnetic susceptibility of these sandstone blocks was found, sandstone could not be used to determine the construction sequence of the Koh Ker monuments (Uchida et al, 2014). In contrast, there are remarkable differences in the chemical composition and magnetic susceptibility of the laterite used in construction of many of its buildings.…”

“…To date, no study except for Uchida et al (2014) has focused on the construction sequence of the Koh Ker monuments.…”

Archaeoastronomy in the Khmer Heartland

“…The entire project exhibits a peculiar orientation at azimuth 76° (flat horizon), which is also shared by the short sides of the baray. Sometimes topographical reasons-such as the slight south-north slope of the terrain-have been advanced for this orientation [Uchida et al 2014], but it is difficult to believe that the architects of such a huge and complex project might have let this fact alone cause them to rotate the whole design by 14°.…”