The laterites of the Angkor monuments, Cambodia
—— The grouping of the monuments on the basis of the laterites ——

Abstract

The magnetic susceptibility, pore size, orientation of the bedding plane and chemical compositions of the laterites used in the Angkor momunents, Cambodia, were measured.
     The laterites used as building blocks of the 25 main monuments can be classified into porous laterites and pisolitic laterites based on the texture. Main constituent minerals of the both type laterites are the same, that is, goethite, hematite, kaolinite and quartz. These laterites are supposed to be formed by weathering of sandstone and conglomerate.
     Based on the average pore size and magnetic susceptibility of these laterites, the investigated monuments can be classified into 5 groups (Groups A to E) except for two monuments of Phnom Krom and Banteay Srei. This grouping is also supported by As, Sb, Sr and V contents of laterites. The laterites of the Groups A, C and E are rich in As, Sb and Sr, but poor in V compared with those of the Groups B and D. These facts suggest that the quarries from which the laterites were mined changed with the time.
     The investigation of the bedding plane of the laterite blocks revealed that the percentage of the laterite blocks with the vertical bedding plane is high (about 30 to 75%) in the monuments constructed prior to Angkor Wat, but low (less than 14%) in Angkor Wat and subsequently constructed monuments.
     Judging from the petrographic similarities of the laterites used for the embankments of the two ponds ajacent to Prasat Suor Prat and Khleangs, it is concluded that the ponds were constructed in the same age as Khleangs.