Non-destructive investigation of sandstone blocks used in the Wat Phu temple in Laos and the Banteay Chhmar temple in Cambodia.

Sandstone blocks quarried from the late Jurassic to the early Cretaceous Red Terrane Formation were used to construct the Wat Phu temple in Laos and the Banteay Chhmar temple in Cambodia. The sandstone blocks of the Banteay Chhmar temple are gray to yellowish brown in color and their magnetic susceptibilities and Sr contents are relatively high, similar to the sandstone blocks used in the Angkor monument. In contrast, the Wat Phu temple consists of reddish sandstone blocks with significantly lower magnetic susceptibilities and Sr contents than those used in the Banteay Chhmar temple and Angkor monument. The sandstone blocks of the Banteay Chhmar temple were likely supplied from quarries in Ta Phraya, Thailand, and those of the Wat Phu temple are likely to have been supplied from the area near these temples. The Red Terrane Formation is widely distributed throughout Mainland Indochina, and most of these sandstones show low magnetic susceptibilities and low Sr contents, similar to those of the Wat Phu temple. Sandstone with high magnetic susceptibilities and high Sr contents is found in the sandstone quarries in Ta Phraya and the southeastern foothill of Mt. Kulen, which is the supply source of the sandstone blocks used in the Angkor monument, early buildings of the Bakan monument, and Banteay Chhmar temple. The sandstone with high magnetic susceptibility and high Sr content is distributed in limited areas and implies a weak degree of weathering during the sandstone formation process or a difference in the source rocks.